QF-60-56 Rev.02 Annual-Mechanical-Finishing Line预防性维护表-年度-机械-精整线

合集下载

变频器主电路接线端子及连接方式

THR控制回路以便进行热过载保护。出厂时已将 THR-CM短接。
• 中、大功率情况(>10KW)：
功率较大时，尤其是负载转动惯量较大，频繁制动时，内设动力制动开关管容量难以满足要求，制动单元和制动电阻均需外接。电机的发电反馈会使Ud升高，当制动单元检测到Ud高于某定额时，制动单元光耦及制动管导通，经RB泄放能量。当RB等过热或电机过载时热脱扣使常闭点分断，经THR
• KM——交流接触器，逆变器故障保护时，KM分断，但由于 R0、T0的接入电使控制电路不会断电，故障显示报警信息得以保持。
2. 输出端子的连接
U、V、W端子可直接接电机,多电机并用时最好逐个接入热过载继电器(KH)，常闭触点接于变频器的控制端子，单台电机时无需 KH，逆变器本身具有完善的过载保护功能（OL），但多台并联运行时一台过载，变频器未必过载。过载保护的目的是保护电机。
对应于另一条机械特性。f x fN 为额定频率、额定负载
f N
T TN
时对应的转差频率。当输出
转矩T=0时不补偿，随负载
f
加重，补偿量增加。 • G9S的F28设定转差补偿
f N
功能，设定范围为
T
fN 9.9 ~ 5.0
设定为0时不补偿。
0
TN
• 无需转速闭环可稳速，
受负载变化影响很小。
2. 矢量控制的设定
§6.7 转差补偿、矢量控制和自动
电压调整等功能的设定
1. 转差频率补偿
通常异步机T∝n， n0 n
转差频率f=pn/60 n0
转差频率即转子频率f2。
• 若负载加重，则 n
负载变导致转速改变。
•转差补偿：给定频率未

INTERNATIONAL BANKING AND FINANCIAL MARKET DEVELOPMENTS

BIS QUARTERLY REVIEWNovember 2000INTERNATIONAL BANKING AND FINANCIAL MARKET DEVELOPMENTSBANK FOR INTERNATIONAL SETTLEMENTSMonetary and Economic DepartmentBasel, SwitzerlandCopies of publications are available from:Bank for International SettlementsInformation, Press & Library ServicesCH-4002 Basel, SwitzerlandFax: +41 61 / 280 91 00 and +41 61 / 280 81 00This publication is available on the BIS website ().©Bank for International Settlements 2000. All rights reserved. Brief excerpts may be reproduced or translated provided the source is stated.ISSN 1012-9979Also published in French, German and Italian.Contents*I.Overview of global financial developments:Markets confront shifting expectations (1)Equity markets harbour renewed doubts about earnings (3)Apprehension spills over into corporate bonds and emerging market debt (4)Liquidity in fixed income markets stabilises (5)The depreciating euro poses a quandary for markets and policymakers (5)Rising oil prices add to nervousness (7)Borrowers turn to convertible bonds, floating rate notesand syndicated loans (8)Box: Credit spreads and equity market volatility (10)II.Highlights of international financing1. The international banking market (14)Interbank lending slows but purchases of bank securitiesremain near record levels (15)Flows to US non-banks surpass those to euro area borrowers (15)Japanese banks return to the international banking market (16)Box: Syndicated credits in the third quarter of 2000 (17)Claims on developing countries continue to contract (18)Deposits by developing countries soar (20)Box: International bank and securities financing in Africa (22)2.The international debt securities market (24)Agencies issue heavily while other borrowers pull back (25)The strong US dollar attracts increased issuance (27)Floating rate issuance continues to grow (28)Developing countries concentrate on debt exchanges (29)Box: Bond issues by European telecommunications companies (30)3. Derivatives markets (32)Exchange-traded instruments: slowdown highlightsgrowing divergence with OTC market (32)Over-the-counter instruments: continued market expansion (34)Box: Recent developments in the credit derivatives market (37)III.Special feature: Market liquidity and stress:selected issues and policy implications (38)What is market liquidity? (38)Why do we care (increasingly) about market liquidity? (39)What determines market liquidity under stress? (42)*Queries concerning the contents of this commentary in general should be addressed to Eli Remolona (Tel. +41 61 280 8414, e-mail: eli.remolona@). Queries about specific parts should be addressed to the authors, whose names appear at the head of each part. Queries concerning the statistics should be addressed to Rainer Widera (Tel. +41 61 280 8425, e-mail: rainer.widera@).iWhat can be done to promote robust market liquidity? (45)Box: Forex trading volumes, volatility and spreadsin emerging market countries (49)IV.Special feature: Size and liquidity of government bond markets (52)The search for liquidity (53)Does size matter for liquidity? (53)Creating size through lumping (55)The trade-off between size and crowding-out (56)Liquidity during the transition in shrinking and growing markets (58)Box: Composition of US dollar foreign exchange reserves by instrument (59)V.Special feature: Hedge funds (61)Structure, characteristics and attractiveness of hedge funds (61)Hedge funds and episodes of financial market turmoil (64)The 1992 ERM crisis (65)The Asian currency crises of 1997, and beyond (65)The near-collapse of LTCM (67)The policy response (68)Hedge funds post-1998: dinosaurs or Darwinian survivors? (69)V.Structural and regulatory developments (72)Initiatives and reports concerning financial institutions (72)Initiatives and reports concerning financial markets (73)Initiatives and reports concerning market infrastructure (74)Statistical annexList of recent BIS publicationsiiBIS Quarterly Review , November 20001Benjamin H Cohen(+41 61) 280 8921benjamin.cohen@ Eli M Remolona (+41 61) 280 8414eli.remolona@I. Overview of global financial developments:Markets confront shifting expectationsFrom the summer to early autumn of 2000, financial markets moved from a climate of cautious optimism to one of growing apprehension. In July and August, macroeconomic data releases and policy measures signalled a more or less benign financial environment. In September, however, as macroeconomic and corporate earnings forecasts were revised downwards and oil prices rose, market participants suddenly began to show signs of nervousness. In the equity market, a brief rally in August was decisively reversed in September and October. Apprehension spread to corporate bonds, which experienced wider credit spreads and increased scrutiny of highly leveraged issuers, including telecommunications firms. These events were accompanied by a resumption of the euro’s weakening trend, which continued until the end of October. Among other things, this trend appeared to reflect renewed market concerns about growth prospects in the euro area.To some degree, financial market jitters have reflected continued attempts to find equilibrium in a situation of rapid technological change and uncertainty about the persistence of recent high rates of productivity growth in the United States. Equity valuations have tended to rely on optimistic expectations about prospects for continued profit growth, which for a time were reinforced by earnings reports. Once earnings began showing signs of slowing and prominent credit downgrades began to be made, however, equity and debt valuations became vulnerable to sharp revisions of expectations. The strength of the dollar against the euro and other currencies has resulted at least in part fromGraph I.1Activity in cross-border bank loans and securities marketsIn billions of US dollars-30003006009697989900Announcements-3003006009697989900Effective financing: total ¹ Includes both money market instruments and long-term bonds and notes. ² Exchange rate adjusted changes in cross-border bank loans.Data for bank loans are available only up to 2000 Q2. 3 Gross issues minus repayments.Sources: Bank of England; Capital DATA; Euroclear; International Securities Market Association (ISMA); Thomson Financial Securities Data; national data; BIS.BIS Quarterly Review , November 20002Graph I.2Global fixed income and equity marketsWeekly averages2468199819992000Ten-year yields (swap rates in %)0100200300400199819992000Equity indices (end-December 025507510019992000S&P 500 earnings surprises (%)¹ Prior to 1999, Deutsche mark. 2 Dow Jones index of European stocksSources: Bloomberg; Datastream; national data.long-term capital flows from overseas investors into the United States driven by strong confidence in future returns. These flows may also have reflected a complementary scepticism about the ability of Europe and other regions to achieve similar levels of productivity growth through structural reforms.The adverse conditions in financial markets led some firms to defer their borrowing plans. Financial institutions, the largest group of borrowers, reduced their net issuance of international debt securities in the third quarter by 27% relative to the previous quarter. Other borrowers shifted from issuing long-term fixed rate bonds to floating rate or convertible instruments, or went to the syndicated loan market. Nonetheless, the aggregate level of fund raising was maintained, in part because a third group of issuers were relatively less sensitive to concerns about credit risks. In particular, highly rated state agencies and government-sponsored enterprises stepped up their issuance to make up for the absence of other borrowers in the market for long-term fixed rate securities.Despite investors’ increased sensitivity to credit risk, developing country borrowers were able to maintain the recent moderate pace of debt issuance during the third quarter. Latin American and Caribbean countries issued $6.9 billion of international debt securities net of repayments and continued to refinance their Brady debt with cheaper issues at longer maturities. However, spreads on emerging market bond issues widened sharply in October, after more than a year during which they had narrowed appreciably. Equity markets and exchange rates in some countries, particularly in East Asia, were adversely affected by worries about rising oil prices, political instability and the uncertain progress of reform measures.BIS data for the second quarter show that the role of the international banking market continued to accommodate the shift of borrowers to the securities market (Graph I.1), both through banks’ own large-scale purchases and through the provision of bridge loans to borrowers who would subsequently refinance these loans by issuing long-term securities. Evidence from the syndicated loan market shows that telecommunications firms were among the principal users of bridging finance in the first quarter.These firms stepped up their issuance of securities in the second quarter, before the rise in credit spreads in the third sent them back to the syndicated loan market.BIS Quarterly Review , November 20003Equity markets harbour renewed doubts about earningsThe sell-off in global equity markets, which began in late March but showed signs of a reversal over the summer, regained momentum in September and October (Graph I.2, middle panel). The sell-off was concentrated in high-technology stocks. Over the five and a half months from mid-March to end-August, the broad-based S&P 500 index and the Europe-based Dow Jones STOXX index both experienced significant swings but ended up virtually unchanged in local currency terms, while the Nasdaq and Tokyo (TOPIX) indices fell by roughly 15%. A brief rally in August was decisively reversed in early September when analysts revised downwards their earnings projections for semiconductor manufacturers and wireless equipment makers.In October, Nasdaq prices fell by a further 8% as disappointing earnings announcements accumulated,mostly from technology firms. Despite the March-April correction, market valuations had in many cases continued to reflect extremely optimistic forecasts of future earnings growth. Thus, it was frequently the case that a company would report healthy current earnings growth but encounter a negative market response because it did not offer a sufficiently optimistic outlook for the future. The third quarter was also the second in a row to record a decline in the number of companies reporting earnings that exceeded forecasts (Graph I.2, right-hand panel). Because of the interconnected nature of the supply chain and the difficulties of forecasting future growth patterns in high-tech industries,reports of slower sales or investment growth in one sector often had a sharply negative impact on earnings forecasts for other sectors. Investors were also worried about the impact on corporate earnings of a potential growth slowdown in Europe, as well as about the effect of the weak euro on the income of those firms that had not adequately hedged their exposures to foreign exchange risk.The downward revisions in revenue forecasts for high-tech companies and the accompanying decline in their stock prices led investors in East Asia to reduce their expectations about the prospects for the electronics industries based in that region. These expectations added to the woes of those Asian countries that depend heavily on electronics exports, some of which also happened to have stock markets already weakened by other factors. The Seoul market, for example, had suffered from a perception that efforts at financial and corporate reform were faltering, and the Taipei market from political problems. The Seoul market fell 25% in the third quarter and the Taipei market 23%. As the Nasdaq index continued to decline in October, the Seoul market fell a further 16% and the Taipei market a further 13%, that is, by even more than the Nasdaq index.Graph I.3Credit spreads over 10-year swap ratesWeekly averages, in basis points-50050100150199920006001,2001,800199819992000¹ Merrill Lynch US High Yield Master II. ² JP Morgan's Emerging Market Bond Index (EMBI+) spread over 10-year US swap rate.³ Euro/ECU denominated Merrill Lynch high-yield bond index.Sources: Bloomberg; Datastream, Moody's; national data.BIS Quarterly Review , November 20004Graph I.4Liquidity in government bond marketsIn basis points-40-20020199819992000On-the-run liquidity premia¹4812199819992000Yield curve arbitrage indicator²¹ Static spread of the 10-year on-the-run government bond over a zero coupon yield curve. ² Standard deviation of static spreads of all bonds over a zero coupon yield curve (excluding callable bonds).Sources: Datastream; BIS calculations.Apprehension spills over into corporate bonds and emerging market debtConcerns about the health of the corporate sector also resulted in wider corporate credit spreads (Graph I.3). The spread of the Merrill Lynch index of triple-A bond yields over 10-year US dollar swaps rose from virtually zero in early August to nearly 20 basis points in early October, while comparable triple-B spreads rose from 100 basis points to 140. The BBB spread had also widened in February and March, at a time when the market’s attention was focused on the debt buyback strategies of the US Treasury and on the status of US agency paper, but this spread had then stabilised throughout the spring and early summer. Spreads on AAA issues had been more or less constant since autumn 1999. The renewed widening of spreads in the third quarter of 2000 may have reflected concerns about increased leverage, particularly in investment-intensive sectors such as telecommunications.1 The higher spreads in the corporate bond market mirrored the tighter credit standards that, according to a survey by the Federal Reserve, have recently been imposed by bank lending officers in the United States. More generally, both volatile equity markets and higher credit spreads reflected increasing uncertainty over asset values.2 Declines in the overall level of yields for government bonds in the United States and Europe reinforce the picture of a flight to safety among investors.Sensitivity to credit risk also extended to emerging market debt. After narrowing steadily in the previous 12 months, spreads widened sharply in October. A tiering of risk in this market was evident in the fact that the most pronounced widening of spreads was experienced by such countries as Argentina, Brazil, the Philippines and Turkey, countries which had already been facing the widest spreads among the major borrowing countries in their respective regions. Emerging economies that are oil importers were also considered to be more vulnerable than the developed economies to higher oil prices. The problems experienced by the Argentine economy, which led to the announcement of a support package by the International Monetary Fund in November, may have contributed to a further 1See the box “Bond issues by European telecommunications companies” on pages 30-31.2 See the box “Credit spreads and equity market volatility” on pages 10-13.BIS Quarterly Review , November 20005worsening of sentiment towards emerging market debt in the fourth quarter. Nevertheless, as discussed below, capital markets continued to be fairly receptive to debt issues from the developing world for most of the third quarter.Liquidity in fixed income markets stabilisesIn contrast to earlier episodes of widening credit spreads, recent credit concerns about non-financial companies have not been associated with a decline in market liquidity or with worries about the health of the financial sector. The spreads of interest rate swap yields over those on government issues such as US Treasuries and German bunds were more or less unchanged over the period.3 Other closely watched indicators of illiquidity, such as the spreads between on-the-run and off-the-run issues, have been stable or declining (Graph I.4). Stable swap and liquidity spreads are also a sign that, for the moment at least, fixed income markets have adapted to the declining supply of new government issues, after being preoccupied with this question for much of the first half of the year.4 Another sign of the market’s ability to adapt to the new supply conditions has been the fact that yields on 30-year bonds now once again exceed 10-year yields in the United States, after being below them for much of the year. The 30-year yield had been particularly affected by shifting market expectations regarding the path of future supply. At the same time, yields in the two- to 10-year section of the yield curve have fallen significantly below those at the very short end, reflecting downward revisions to the expected course of policy rates and producing an unusual U-shaped term structure.The depreciating euro poses a quandary for markets and policymakersDuring the period under review, the steady weakening of the euro against the US dollar and other currencies raised questions about prospects for price stability in the euro zone and about the market’sGraph I.5Growth forecasts and economic surprises-3-2-10119992000Growth differentials (EMU-US)¹-3-1.501.5319992000Announcement surprises²¹ Difference between EMU area and US GDP forecasts. ² Actual less expected normalised by the standard deviation.Sources: Bloomberg; Consensus Economics; national data.3See the special feature “Market liquidity and stress: selected issues and policy implications” on pages 38-48 for a furtherdiscussion of the relationship between liquidity and credit risk.4See the special feature “Size and liquidity of government bond markets” on pages 52-58 for a discussion of recent trends in government bond supply and their implications.BIS Quarterly Review , November 20006Graph I.6Exchange rates and commodity prices708090100110120130199819992000Exchange rates (1998 = 100)050100150200250199819992000Commodity prices (1998 = 100)Commodity Index.Sources: Datastream; Reuters; BIS calculations.confidence in the European economy. Discussion of causes of the euro’s weakness has focused on the relative growth outlook across the developed economies and on the flow of capital into the United States. The recent bout of weakness was precipitated by the release in August of the closely watched Ifo survey of German business sentiment (Graph I.5). Similar surveys from other euro area countries and the September release of the Ifo survey continued to indicate sluggish economic prospects, while higher inflation figures raised the possibility of further tightening moves by the European Central Bank. More recent releases, such as industrial production data for various countries and the producers’confidence index from the European Commission, suggested a more mixed picture for Europe. Data for the US economy, such as preliminary figures suggesting annualised growth of 2.7% in the third quarter, also indicated a mild slowdown, but these were at first treated positively by financial markets since they supported the optimistic scenario of a “soft landing”.During 1999, some market observers cited the relatively high level of euro-denominated debt issuance as a factor contributing to the euro’s weakness that year. Data for the third quarter of 2000 indicate that issuers have recently begun to revert to their earlier pattern of issuing in the stronger currency. In particular, as has tended to be the case in past periods of dollar strength, the share of dollar-denominated securities in international issuance was relatively high. This shift may in turn remove one of the factors that has been contributing to the euro’s weakening trend.While the euro’s gradual depreciation during 1999 and the early part of 2000 had been seen by market participants as having helped to promote a needed recovery in European output, its more recent weakness against the other major currencies raised fears of rising euro zone inflation, a continued tightening of monetary policy by the ECB and an associated decline of confidence, with negative consequences for growth. After trading in a narrow range of 0.94-0.95 to the US dollar and 100-102 to the Japanese yen throughout June and July, the euro resumed its fall in late July (Graph I.6). By mid-September it had reached $0.85 and ¥90. Concerted intervention by the ECB, the Federal Reserve, the Bank of Japan, the Bank of Canada and the Bank of England on 22 September temporarily supported the euro at $0.87 and ¥95 up to early October. The probability distributions implied by risk reversal prices indicate that, after the intervention, short-run market expectations about the dollar/euro rate returned more or less to where they had stood at the end of August (Graph I.6).The euro continued to weaken during most of October, even against economically linked currenciessuch as the Swiss franc and pound sterling, before recovering somewhat towards the end of the month accompanied by a new round of ECB intervention.Ordinarily, rising interest rates in Europe might have been expected to support the euro, particularly when US rates have been flat or declining. While the ECB’s summer tightening moves had already been priced into forward interest rates and thus did not lead to a revision of market expectations, the weakening US growth outlook led to a downward shift in the near-term path of forward US dollar rates. As of end-October, a neutral or slightly looser monetary policy stance by the Fed had been priced into the yield curve up to two years (Graph I.7). Nevertheless, and despite the decline in US equity prices since March, the promise of high returns in US equity markets appears to have continued to support the dollar.5 The strong dollar has in turn been perceived as a positive factor for the US economy, in that it has helped to dampen inflationary pressures in conditions of strong domestic demand. Conversely, the weak euro has been seen to have exacerbated inflationary pressures and to have signalled waning market confidence regarding growth prospects in the euro area.The Japanese yen has also strengthened against the euro, trading in a range of ¥105-110 to the dollar,with the help of data indicating 1.0% GDP growth in the second quarter and a rise in the Tankan business sentiment index in September. However, confidence in a strong Japanese recovery was restrained by the persistent weakness of the financial sector, which was further shaken by the failure of a large retailer in July and two insurance companies in October.Rising oil prices add to nervousnessAnother factor clouding the outlook for policymakers and market participants has been the 18-month long increase in crude oil prices (Graph I.6, right panel). In US dollar terms, most of the increase in oilGraph I.7Three month implied forward rates66.577.509.0003.0109.0103.0209.02Eurodollar4.555.5609.0003.0109.0103.0209.02Euro libor00.511.509.0003.0109.0103.0209.02EuroyenEach curve shows the three-month implied forward rates for futures contracts commencing on the dates shown on the horizontal axis, as observed on the date listed in the legend. The forward rates are derived from interest rate deposit contracts of different maturities.Source: Bloomberg.5For a discussion of the interactions between stock market returns, equity flows and exchange rates, see Henri J Bernard and Gabriele E B Galati, “Special feature: The co-movement of US stock markets and the dollar” in the August 2000issue of the BIS Quarterly Review.prices had already occurred in 1999, with prices rising about two and a half times from January 1999 to March 2000, in line with stronger growth in the developed economies and the revival of demand from the emerging economies. While dollar prices fluctuated widely in the spring and summer of 2000, they returned to their March levels in August before rising again in the autumn as the situation in the Middle East worsened. For European countries, the weak euro has exacerbated the effect of the oil price increases. In euro terms, oil prices more than tripled from January 1999 to March 2000, and rose by an additional 25% between March and early October 2000. High ad valorem taxes on petrol in European countries have magnified the ultimate price impact for consumers. These factors may have accounted both for the wave of petrol-related strikes and protests in several European countries in September, and for the perception that the ECB may respond more aggressively to energy price inflation than the Fed. However, it is also widely recognised that oil represents a smaller fraction of consumption throughout the developed world today than it did at the time of the 1970s price shocks, so that the overall inflationary and growth impact is likely to be less pronounced.Borrowers turn to convertible bonds, floating rate notes and syndicated loansApprehension in financial markets had an immediate impact on borrowers in the international securities market. Some firms postponed their borrowing plans, while others turned to ways of raising funds that were relatively less sensitive to rising credit spreads. Financial institutions, the largest group of borrowers, reduced their presence in the primary market, raising a net $115 billion in the third quarter of 2000, a 27% decline from the previous quarter. Net issuance by German financial institutions, in particular, declined significantly, because of the less favourable market conditions for euro-denominated paper. Among non-financial corporations, those lacking triple-A credit ratings found it increasingly difficult to raise funds from the securities market. Issuance by telecommunications firms, in particular, slowed down sharply in the third quarter, some of them turning instead to the syndicated loan market. To raise funds without paying the full credit spread on fixed rate securities, most of those telecom firms that did tap securities markets for large amounts issued bonds that would be exchangeable for equity. Other corporate issuers turned to floating rate structures.The rise in credit spreads, however, did not lead to an aggregate decline in net issuance of international debt securities. Issuers raised a net $259 billion in the third quarter, almost as much as they had raised in the second. State agencies and government-sponsored enterprises largely made up for the reduced activity of other borrowers in the primary market. With the advantage of triple-A credit ratings, these agencies more than doubled their net debt issuance in the third quarter. In the United States, the Federal National Mortgage Association (“Fannie Mae”) and the Federal Home Loan Mortgage Corporation (“Freddie Mac”) launched over $50 billion of new international issues combined, accounting for the bulk of gross issuance by the agency sector during the quarter. With a view to offering alternative benchmarks to government securities, these agencies concentrated their issuance in large long-term, fixed rate issues.Developing countries for their part brought a moderate amount of new debt issues to market and engaged in debt exchanges, with the benefit of generally narrower sovereign spreads during the summer. These countries raised a net $8 billion from the securities market in the third quarter. Latin American issuers were especially active, while Asian and central and eastern European issuers stayed away from the primary market (Graph I.8). Some Latin American issuers floated eurobonds in order to buy back relatively more costly Brady bonds. In August, Brazil successfully issued some $5 billion of 40-year debt in exchange for an equivalent amount of Brady bonds. Other countries were said to be exploring similar exchange offers.In contrast to the trend in securities issuance, bank lending to developing economies remained limited in the second quarter of 2000 (the most recent one for which comprehensive data are available), with claims on developing countries contracting by a relatively small amount. A small increase in claims on Latin American countries was not enough to offset continued repayments by Asian borrowers. However, the 1998-99 cycle of net repayments by developing countries appears to have ended, and。

舍维尼玛科宝

Revised 07/2023 Issue 1HIGH SOLIDS, SURFACE-TOLERANT EPOXY PRIMER A 2-pack epoxy primer coat for steel and galvanized surfaces.Economically and high-performance corrosion protection also for manually prepared surfaces and surfaces prepared by high-pressure water jetting. Low solvent content according to Protective Coatings Directive of German Paint Industry Association (VdL-RL 04).▪ Surface tolerant▪ H igh film thickness and diffusion resistance combined with very good surface wetting properties and adhesion result in a very high safety margin for good corrosion protection▪ Fast initial drying and full curing▪ High build application▪ Very economical due to high volume solidsCan be used as a robust versatile overcoatable primer for corrosion protection on steel exposed to atmosphere. Especially suitable for use onsurfaces where only manual preparation (wire brushing or power tool cleaning) or high-pressure water jetting is feasible or economic.Volume Solids:Aluminium shade: 67 ± 2%Red-brown/sand-yellow: 80 ± 2% (ISO 3233-3) Weight Solids:Aluminium shade: 71 ± 2%Red-brown/sand-yellow: 83 ± 2%VOC:255 g/l determined practically in accordance withProtective Coatings Directive of German PaintIndustry Association (VdL-RL 04).307 g/l calculated from formulation to satisfyEC Solvent Emissions Directive.205 g/kg calculated from formulation to satisfyEC Solvent Emissions Directive (UK).Colours:Aluminium, material no. 694.01Red-brown, material no. 694.06Sand-yellow, material no. 694.02 and 650.02Flash Point:Base: 30°C, Hardener: 27°CCleaner/Thinner:Cleaner 26 (for cleaning).Thinner EG for thinning with max. 5% to adapt theviscosity.Thinning will affect VOC compliance, sag toleranceand dry film thicknesses.Pack Size: A two component material supplied in separatecontainers to be mixed prior to use:Aluminium shade: 28 kg (21.5 litre), 14 kg (10.7 litre)and 4 kg (3.0 litre) units when mixed.Red-brown/sand-yellow: 28 kg (18.6 litre), 14 kg(9.3 litre) and 4 kg (2.6 litre) units when mixed.Volume will vary with colours and density.Mixing Ratio:82 parts base to 12 parts hardener by weight.4.3 parts base to 1 part hardener by volume. Density:Aluminium shade: 1.3 kg/lRed-brown/sand-yellow: 1.5 kg/l(may vary with colours)Shelf Life: 2 years from date of manufacture, stored in originallysealed containers in a cool and dry environment.Recommended Application Methods:Airless Spray, Conventional Spray, BrushTypical Thickness:Recommended Spreading Rate Per CoatAluminium shade Typical Maximum SagDry100 µm240 µmWet149 µm358 µm TheoreticalConsumption*0.194 kg/m²0.149 l/m²TheoreticalCoverage*5.15 m²/kg6.70 m²/lRed-brown/sand-yellow Typical Maximum SagDry100 µm240 µmWet141 µm338 µm TheoreticalConsumption*0.211 kg/m²0.141 l/m²TheoreticalCoverage*4.73 m²/kg7.10 m²/l* T his figure makes no allowance for surface profile, uneven application, overspray or losses in containers and equipment.Film thickness will vary depending on actual use and specification.Pot Life:+ 5°C+ 20°C6 hours 4 hoursPot life is dependent on temperature and volume.Revised 07/2023 Issue 1HIGH SOLIDS, SURFACE-TOLERANT EPOXY PRIMERFor 100 μm Dry Film Thickness:+ 5°C+ 20°C + 30°C Dry to handle (Drying Stage 6*)12 hours 6 hours 3 hours To Recoat12 hours6 hours3 hours*ISO 9117Maximum recoat time is 1 year. Prior to further applications allcontamination must be removed. In the case of extended recoating times consult Sherwin Williams customer service.Final cure: 1-2 weeks, depending on film thickness and temperature.These figures are given as a guide only. Factors such as airmovement, film thickness and humidity must also be considered.• A pproved according to German standard ‘TL KOR-Stahlbauten, Blatt 94’.• A pproved according to German standard ‘TL KOR-Stahlbauten,Blatt 50’.Ensure surfaces to be coated are clean, dry and free from all surface contamination such as oil, grease, dirt and corrosion products to achieve satisfactory adhesion.For contaminated and weathered surfaces e.g. primed areas we recommend to clean with Cleaner Wash.Steel surfaces shall be blast-cleaned to Sa 2½ according to ISO 8501-1 (ISO 12944-4) in case of permanent condensation.Hot-dip galvanized surfaces shall be prepared by degreasing or, in case of permanent condensation, sweep blasting according to ISO 12944-4 with a non-ferrous blasting abrasive.Manually prepared surfaces shall be prepared by wire brush or power tool to surface preparation grade St 2 according to ISO 8501-1 (ISO 12944-4), in case of atmospheric exposure. Even ultra-highpressure water jetting according to ISO 8501-4 Wa 2 with a maximum flash rust grade M is also acceptable.Old coatings: In case of well adhering coating systems, careful cleaning (e.g. by water jetting) is sufficient. Loose particles must be removed, damaged areas should be minimum prepared in accordance with PSa 2, PMa or PSt 2 and primed with Macropoxy ® Primer HE N.The required surface preparation/cleaning and compatibility of thesystem should be determined with trial areas.Stir component A very thoroughly using a mechanical paint mixer (start slowly, then increase up to approx. 300 rpm). Add component B carefully and mix both components very thoroughly (including sides and bottom of the container). Mix for at least 3 minutes until a homogeneous mixture is achieved. We recommend to fill the mixed material into a clean container and mix again shortly as described above to avoid incorrect mixing. 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Any reduction must be compliant with existing VOC regulations and compatible with the existing environmental and application conditions.Airless SprayUnit: Efficient airless equipmentTip Size: 0.38 – 0.53 mm (0.015 – 0.021 inch)Fan Angle: 40° - 80°Operating Pressure: min. 180 bar (2600 psi)Spray hoses: Ø ⅜ inch (10 mm), max. 20 m+ 2 m with reduced Ø of ¼ inch (6 mm)The airless spray details given above are intended as a guide only.Details such as fluid hose length and diameter, paint temperature and job shape and size all have an effect on the spray tip and operating pressure chosen. However, the operating pressure should be the lowest possible consistent satisfactory atomisation.As conditions will vary from job to job, it is the applicators responsibility to ensure that the equipment in use has been set up to give the best results.If in doubt consult Sherwin-Williams customer service.Conventional SprayAtomising Pressure: 3 - 5 bar (43 - 73 psi)Tip Size: 1.5 – 2.5 mm (0.06 – 0.10 inch)Brush and Roller• Surface preparation St 2 or St 3• With brush application best penetration and surface wetting is achievedRevised 07/2023 Issue 1HIGH SOLIDS, SURFACE-TOLERANT EPOXY PRIMERSteel resp. patch up of spots on hot-dip galvanized surfaces 2 x Macropoxy ® Primer HE NOvercoatable with 1- and 2-pack coatings e.g Macropoxy ®, Acrolon ® and Kem Kromik ®, provided the surface to be coated is clean, dry and free from contamination.Example Blatt 941 x Macropoxy ® Primer HE N 1 x Macropoxy ® EG-1 VHS1 x Acrolon ® EG-4 or Acrolon ® EG-5Old coatingsMacropoxy ® Primer HE N can be used on a variety of sound 1-pack and 2-pack coats for refurbishment.Note: Macropoxy ® Primer HE N is not recommended for permanentimmersion.Drying times, curing times and pot life should be considered as a guide only.Epoxy Coatings - Tropical UseEpoxy coatings at the time of mixing should not exceed a temperature of 35ºC. 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If the air and substrate temperatures exceed 40ºC and epoxy coatings are applied under these conditions, paint film defects such as dry spray, bubbling and pinholing etc. can occur within the coating.Chemical resistance:Resistant to weathering, de-icing salts, oils and grease and short term exposure to fuels and solvents.Temperature resistance:Dry heat up to + 150°C, short term up to + 200°C.Increased humid ambient temperature up to + 40°C.Numerical values quoted for physical data may vary slightly from batchto batch.Consult Product Health and Safety Data Sheet for information on safestorage, handling and application of this product.Whilst all statements made about our products (whether in this data sheet or otherwise) are correct and accurate to the best of our knowledge, we have no control over the quality or the condition of the substrate, the application conditions or the many other factors affecting your use and application of our product.The appropriateness of the product under the actual conditions ofapplication or intended use must be determined exclusively by you. 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It is the users responsibility to ensure they are using the most up to date version – this can be found at: /protectiveEMEA .If this datasheet has been translated, then it has been done using the English version as the source. In case of any queries, please refer to the master English version which can be found at: /protectiveEMEA .。

信息检索练习题(1)

1.小王在某个数据库中检索到了50篇文献，查准率和查全率分别为40％、80％，则全部相关文档有25篇。

2.INTERNET是基于TCP/IP 协议的。

3.文件ABC.001.TXT的后缀名是TXT 。

文件类型是文本文件。

4.多数网页采用HTML编写，这里的HTML指的是：超文本标识语言。

5.目录型搜索引擎主要提供族性检索模式，索引型搜索引擎主要提供特性检索模式。

6.在使用搜索引擎检索时，URL:ustc可以查到网址中带有ustc的网页。

7.根据索引编制方式的不同，可以将搜索引擎分为索引型搜索引擎和网络目录型搜索引擎。

8.按文献的相对利用率来划分，可以把文献分为核心文献、相关文献、边缘文献。

9.定期（多于一天）或不定期出版的有固定名称的连续出版物是期刊。

10.检索工具具有两个方面的职能：存储职能、检索职能。

11.以单位出版物为著录对象的检索工具为：目录。

12.将文献作者的姓名按字顺排列编制而成的索引称为：作者索引。

13.利用原始文献所附的参考文献，追踪查找参考文献的原文的检索方法称为追溯法，又称为引文法。

14.已知一篇参考文献的著录为：”Levitan, K. B. Information resource management. New Brunswick: RutgersUP,1986”，该作者的姓是：Levitan 。

15.检索语言可分为两大类：分类语言、主题词语言。

16.LCC指的是美国国会图书馆分类法。

17.当检索关键词具有多个同义词和近义词时，容易造成漏检，使得查全率较低。

18.主题词的规范化指的是词和概念一一对应，一个词表达一个概念。

19.国际上通常根据内容将数据库划分为：参考数据库、源数据库、混合数据库。

20.查询关键词为短语"DA TA OUTPUT"，可以用位置算符(W)改写为：DA TA(W) OUTPUT 。

21.著录参考文献时，对于三个以上的著者，可以在第一著者后面加上et al. ，代表"等人"的意思。

脱硫胺液除油新技术的工业侧线试验

脱硫胺液除油新技术的工业侧线试验张百庆，吴红梅（陕西延长石油（集团）有限责任公司永坪炼油厂，陕西延川，717208）摘要：为解决炼油厂脱硫胺液带油、影响净化干气产品质量及下游硫磺回收装置运行等问题，某炼油厂采用AMFD自适应高效除油技术+MPE颗粒除油脱固技术+CFC组合纤维深度破乳3级分离除油技术，进行了15d工业侧线试验。

试验结果表明：通过该技术设备净化，胺液中油含量由3.5%降至1%，除油效果显著，提高了循环胺液的品质，保障了干气脱硫及硫磺回收装置的稳定运行，具有较高的工业化价值。

关键词：胺液；油水分离；侧线试验中图分类号：TE624.5文献标识码：A文章编号：1671-4962（2024）01-0026-04 Industrial side-line experiment of a new technology for oil removal fromdesulphurized amine solutionZhang Baiqing，Wu Hongmei（Yongping Refinery，Shaanxi Yanchang Petroleum（Group）Co.，Ltd.，Yanchuan717208，China）Abstract:In order to solve the problems of oil carrying in desulphurized amine liquid in refinery,affecting the quality of purified dry gas products and the operation of downstream sulfur recovery unit,a refinery adopted AMFD adaptive efficient oil removal technology+MPE particle oil removal technology+CFC composite fiber deep demulsification3-stage separation and oil removal technology to carry out a15-day industrial side-line experiment.The experiment results showed that the oil content in the amine solution was reduced from3.5%to1%by the purification technology to get the remarkable oil removal effect.It improved the quality of the circulating amine solution,guaranteed the stable operation of the dry gas desulfurization and sulfur recovery equipment with high industrial value.Keywords：amine solution；separation of oil and water；side-line experiment炼油行业处理油品精制过程中产生的含硫化物的酸性气体一般采用胺法脱硫技术，包括吸收、解吸、再生和硫回收等4个步骤。

Effects of heat treatments on the microstructure and mechanical properties of a 6061 aluminium alloy

Materials Science and Engineering A 528 (2011) 2718–2724Contents lists available at ScienceDirectMaterials Science and EngineeringAj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /m s eaEffects of heat treatments on the microstructure and mechanical properties of a 6061aluminium alloyD.Maisonnette a ,M.Suery b ,D.Nelias a ,∗,P.Chaudet a ,T.Epicier caUniversitéde Lyon,CNRS,INSA-Lyon,LaMCoS UMR5259,F-69621,FrancebUniversitéde Grenoble,SIMaP,UMR CNRS 5266,BP46,Domaine Universitaire,38402Saint Martin d’Hères Cedex,France cUniversitéde Lyon,CNRS,INSA-Lyon,Mateis UMR5510,F-69621,Francea r t i c l e i n f o Article history:Received 23August 2010Received in revised form 3December 2010Accepted 3December 2010Available online 9 December 2010Keywords:6061Aluminium alloyThermomechanical propertiesElectron beam welding stress–strain curves Yield stressHardening precipitatesa b s t r a c tThis paper describes the mechanical behavior of the 6061-T6aluminium alloy at room temperature for various previous thermal histories representative of an electron beam welding.A fast-heating device has been designed to control and apply thermal loadings on tensile specimens.Tensile tests show that the yield stress at ambient temperature decreases if the maximum temperature reached increases or if the heating rate decreases.This variation of the mechanical properties is the result of microstructural changes which have been observed by Transmission Electron Microscopy (TEM).© 2010 Elsevier B.V. All rights reserved.1.IntroductionThe study presented in this paper is concerned with the widely used 6061-T6aluminium alloy.It is an age hardenable alloy,the mechanical properties of which being mainly controlled by the hardening precipitates contained in the material.When the material is subjected to a solution heat treatment followed by a quenching and a tempering treatment,its mechanical properties reach their highest level and become very good compared to other aluminium alloys.The as-obtained microstructure of the material is called T6temper (tempering around 175◦C).Another interest-ing characteristic of the AA6061is its good weldability.Because of these favorable properties,the AA6061alloy is used in the trans-port and the public works domains (framework,pylon,handling equipment ...)and also for complex structures assembled by weld-ing [1–3].The present work is part of the early qualifying study of a pres-sure vessel to be used in an experimental nuclear reactor.The approximate size of the vessel is ﬁve meters height with a diameter of about one meter.Several ferrules in AA6061-T6should be assem-bled together by electron beam (EB)welding.The aim of the work presented in this paper is to evaluate the inﬂuence of the weld-ing process on the mechanical properties of the material at room∗Corresponding author.E-mail address:daniel.nelias@insa-lyon.fr (D.Nelias).temperature.The change of mechanical properties is due to met-allurgical phenomena such as dissolution,growth or coarsening of precipitates,which have been also observed.It is commonly assumed that the generic precipitation sequence in Al–Mg–Si alloys is [4,5]:SSSS →GP →␤→␤→␤-Mg 2Si(1)Here SSSS represents the super-saturated solid solution and GP stands for Guinier–Preston zones.The sequence (1)will be consid-ered in this work.However,some authors give more details about this sequence [5–12]particularly Ravi and Wolverton [5]who gave a detailed inventory of the compositions of the phases contained in an Al–Mg–Si alloy.The compositions generally accepted for the most common precipitates are listed in Table 1.According to the literature [6–9,13,14],the T6temper of the 6XXX alloys involves very thin precipitates.They are ␤ needle-shaped precipitates oriented along the three 100 directions of the matrix.Their size is nanometric and they are partially coherent.The study presented in this paper includes High Resolution Transmission Electron Microscopy (HRTEM)observations of the investigated 6061-T6alloy in order to characterize the precipita-tion state of the T6temper.These observations will allow deﬁning a precipitate distribution of reference for the initial alloy.From this initial state,thermal loadings are applied on specimens which are thereafter observed by TEM.The investigated thermal loadings will also be applied on tensile specimens in order to evaluate the variation of the resulting mechanical properties.0921-5093/$–see front matter © 2010 Elsevier B.V. All rights reserved.doi:10.1016/j.msea.2010.12.011D.Maisonnette et al./Materials Science and Engineering A528 (2011) 2718–27242719Table1Compositions of the precipitates contained in Al–Mg–Si alloys.Phase CompositionGP zone Mg1Si1␤ Mg5Si6␤ Mg9Si5␤Mg2SiFor experimental convenience,the study will be limited to the solid state of the alloy.This means that the maximum temperature to be used is below582◦C(solidus temperature for the AA6061)and the phenomena occurring in the melting pool of the weld will not be taken into account here.Furthermore,the mechanical characteriza-tions and microstructural observations will be carried out at room temperature after the thermal loading.This will allow the char-acterization of the material at various points of the Heat Affected Zone(HAZ)after welding(and not during the welding process). For that purpose,the required thermal loadings should reproduce the temperature evolution in the HAZ with high heating rates up to200K/s.An experimental device has been speciﬁcally developed to meet these requirements.Atﬁrst,the design of the device will be brieﬂy presented.Then,the results of the mechanical charac-terizations and microstructural observations will be presented and discussed.2.Experimental procedure2.1.Experimental heating deviceThe main purpose of the experimental heating device is to repro-duce on a tensile specimen the thermal history encountered by each point of the heat affected zone during welding of the vessel.The highest temperature to be studied is thus T=560◦C,very close to the solidus temperature of582◦C which should not be reached.To do so,an accurate control of the temperature has been set up.Fur-thermore,the device should be able to reproduce the heating rate observed in the HAZ of an electron beam welding(up to200K/s). This heating rate has been evaluated by measuring it during an instrumented welding experiment.The second aim of the device is to apply a mechanical loading on a specimen in order to mea-sure the mechanical properties of the material.The mechanical and thermal loadings have to be used simultaneously in order to perform tensile tests at high temperature for further study or to compensate for thermal expansion of the specimen during heating. Therefore,the experimental equipment includes a heating device and a mechanical testing machine.2.1.1.Design of the deviceA convenient method to heat aluminium alloys at very high rate is by Joule effect.Another way would be by induction heating but it is not efﬁcient enough to obtain the required heating rate on alu-minium alloys.For this reason,a resistive heating device has been designed and constructed.In order to measure the temperature of the specimen during heating,a thermocouple has been spot welded on the specimen surface.The strains are measured by means of an extensometer with ceramic tips.The Joule heating device is a power supply,made of an electrical transformer and a thyristor bridge,providing a continuous current whose intensity is controlled by a thermal controller.Water cooled cables and clamping systems are used to connect the specimen to the heating device.A graphite resistor is added in series in order to increase the potential difference across the generator allowing a good temperaturecontrol.Fig.1.Temperature distribution measured by thermocouples along the tensile specimen.2.1.2.Specimen designA specimen heated by using Joule effect reacts as an electrical resistor.Its electrical resistance depends on the material electri-cal resistivity and the specimen shape which has to be optimized in order to reach the desired heating rate(up to500K/s).More-over,the temperature must be uniform over the measurement area (between the extensometer tips)and the specimen volume should be large enough for the microstructure to be representative of the alloy in real structures.A FEM simulation was performed to optimize the size and shape of the specimen.The used software,called Sysweld®was devel-oped by ESI Group.The simulation is carried out by using an electro kinetic model[15].The density d and the thermal conductivity K of the alloy were considered to vary with temperature.A paramet-ric study shows that a diameter of6mm is required to obtain a heating rate up to500K/s.A specimen length of100mm is also required to have a low thermal gradient.Fig.1shows the tempera-ture distribution in the specimen.The gradient has been measured with10thermocouples placed all over the length of a specimen peak-heated to350◦C at a heating rate of15K/s.2.1.3.Regulation set-upThe experimental device has been designed to reach high heat-ing rates.An accurate control of the temperature is required in order to avoid overshoots.To do so,a PID controller has been used [16–19].The resulting thermal loading is slightly delayed but the heating rate is equal to the desired one.The cooling rate is maxi-mum at the highest temperature(of the order of23K/s at500◦C) and decreases during cooling;it drops to about6K/s when temper-ature becomes lower than150◦C.2.2.Transmission Electron MicroscopyThe experimental device presented previously has been used to heat specimens for both mechanical measurements and TEM observations.Two types of microstructural observations have been carried out during this work.Theﬁrst one is a detailed observation of the microstructure of the material in the T6temper by means of HRTEM(High Resolution Transmission Electron Microscopy) and the second one by means of classical TEM to compare the microstructure of the alloy for three different states of precipita-tion.They were conducted on a JEOL2010F microscope operating at200kV,which belongs to the Centre Lyonnais de Microscopie (CLYM)located at INSA Lyon(France).TEM allows only very local observations so it was not intended to measure accurately the volume fraction of the precipitates;also not enough precipitates were analyzed to obtain an accurate mean radius.2720 D.Maisonnette et al./Materials Science and Engineering A528 (2011) 2718–2724The samples used in TEM are thin lamellas.A disk with a thick-ness of about200␮m is extracted from the heated specimen by means of a diamond wire saw.Its diameter is then reduced by punching.The disk is thinned to electron transparency(thickness to about200nm or less)by electropolishing using an electrolytic bath composed of20%of HNO3in methanol.The bath is cooled at−30◦C with liquid nitrogen[20].A Precision Ion Polishing System(PIPS) is used in order to accomplishﬁnal thinning and cleaning by ion milling.Some EDX(Energy-dispersive X-ray spectroscopy)analy-sis were performed with an Oxford Instruments analyzer,using a nanoprobe(about3nm in diameter)in the TEM to estimate the composition of the precipitates in the T6state.2.3.Mechanical characterizationTensile tests have been carried out at room temperature on spec-imens previously heated to peak temperatures of200,300,400,500 and560◦C with various heating rates(0.5,5,15,50,200K/s)in order to measure their mechanical properties.The thermal loadings are representative of the thermal histories encountered in EB welding.Three parameters have been investigated.Theﬁrst one is the maximum temperature reached during heating at a given heating rate(r=15K/s).The second one is the heating rate for a given max-imum temperature(T=400◦C).The third one is the dwell time at T=560◦C.This last study is not representative of a welding opera-tion but will allow understanding the variation of the mechanical characteristics during holding at a given temperature which cor-responds to the solution treatment of the alloy.For each test,the specimen is heated to the required temperature while compensat-ing for thermal expansion,then it is cooled to room temperature andﬁnally deformed until fracture at a strain rate of10−2s−1.Dur-ing the test,for a strain close to1.5%,an unloading is performed to measure the elastic modulus.3.Results3.1.HRTEM observations of the material in the T6temperThe aim of the HRTEM investigation on the AA6061-T6is to mea-sure the size of some hardening precipitates and to evaluate their composition in order to characterize the microstructure of the ref-erence T6state.The precipitates present in this state are hard to see owing to their very small size and because they are partly coherent with the aluminium matrix.HRTEM is thus mandatory to image the precipitates.Fig.2(a)shows a TEM picture at high magniﬁcation.Two needle-shaped precipitates can be seen:•Theﬁrst one is oriented along the[001]direction.Its cross sec-tion is observed making its diameter measurable accurately.The measure gives a diameter of about4nm.•The second one is oriented along the[100]direction.It is observed lying in the thin foil.The diffractogram,obtained by using Fourier transform,asso-ciated to theﬁrst precipitate is shown in Fig.2(b).In addition to the{200}diffraction spots associated with the aluminium matrix, weak aligned spots prove that the atomic state is partially disor-dered as for pre-␤ phases.At last,an EDX analysis carried out on the needle-shaped precip-itates by means of a3nm probe gives an atomic ratio X Mg/X Si=1.29 (with a standard deviation of0.3).This value is the average result of measurements onﬁve precipitates.3.2.Classical TEM observations of the microstructural changesFollowing the detailed study of the T6temper,the precipitates for various states were observed by means of classical TEM.The aim is to evaluate the evolution of the microstructure(size and vol-ume fraction of precipitates)as a function of the thermal loading previously submitted to the pared to HRTEM,classi-cal TEM is a better way to evaluate the volume fraction because it allows a larger area to be observed at lower magniﬁcation.How-ever classical TEM is worse than HRTEM to measure accurately the diameter of the precipitates because the images at high magniﬁca-tion are often fuzzy(a difﬁculty inherent to the diffraction contrast in conventional TEM).parison of three precipitation statesThe reference microstructure of the T6temper is here compared to states observed after a heating up to300◦C and400◦C at a heat-ing rate of15K/s and no dwell time at the maximum temperature.Fig.3shows three micrographs obtained from representative sample areas for the three investigated states.In the case of the specimen heated to400◦C,some precipitates with a needle shape are present in the picture.These precipitates are very large,with length between65and170nm and a mean value of112nm,and their diameter ranges between5and11nm with a mean value of 7.35nm.The mean values are calculated by taking into account ten precipitates observed on different pictures.However it should be mentioned that the precipitates could be cut by the sample prepa-ration,consequently the length given above should be considered as indicative only.They will be used to compare the precipitation state.In the two other cases,the precipitates are smaller.Their length is between20and40nm with a mean value of29nm for the T6 temper and between15and40nm with a mean value of25nm for the specimen heated to300◦C.Their diameter ranges between 3.75and4.6nm with a mean value of4.45nm for the T6temper and between2and4nm with a mean value of2.6nm for the specimen heated to300◦C.3.2.2.Precipitate volume fraction evaluationThe precipitate size can be measured by means of TEM pictures. However,it is much more difﬁcult to determine the precipitate volume fraction.Indeed,projections obtained by TEM correspond to volumetric observations but the thickness of the sample is not known accurately.In order to get a rough estimate of the precipi-tate volume fraction,TEM micrographs were compared to pictures obtained by modeling.A computer software has thus been devel-oped in Matlab to simulate these images.Based on three simple parameters describing the precipitation state,the program can reproduce a needle-shaped precipitate distribution in a sample with a uniform thickness.The three parameters are the volume fraction(f v),the mean radius of the needle precipitates(r avg)and their mean length(L avg).A Gaussian size distribution is arbitrarily assumed for the radius and the length with a variance of1and36,respectively.The size distributions are discretized in one hundred classes of size.Once the thickness isﬁxed(illustrations will be given here for a100nm thick material),the total volume is calculated and an iterative algo-rithm increases step by step the number of precipitates in each class to obtain the volume corresponding to the desired f v.The pre-cipitates are then shown graphically on a2D view by distributing them uniformly along the three 001 directions of the Al-matrix, which corresponds to the viewing directions of the TEM micro-graphs shown in Figs.2and3.Fig.4compares the precipitation state observed in the specimen heated to300◦C to two modeled states,theﬁrst one with a volume fraction of3%(Fig.4(a))and the second one with a volume fraction of1.6%(Fig.4(c)).It clearlyD.Maisonnette et al./Materials Science and Engineering A528 (2011) 2718–27242721Fig.2.HRTEM observations of needle precipitates in AA6061-T6.(a)Lattice image at high magniﬁcation;(b)diffractogram(numerical Fourier transform)of the micrograph showing diffraction spots(arrows)arising from the precipitate in addition to the square lattice of the aluminium fcc phase along[001].appears that f v=3%is not representative of the real precipitation state because it is too dense.The volume fraction of1.6%is obvi-ously closer to the volume fraction observed by TEM.The same type of study carried out for the two other investigated states givesa similar volume fraction.3.3.Mechanical characterizationAs indicated previously,three parameters have been investi-gated.Theﬁrst one is the maximum temperature reached at a given heating rate(r=15K/s).The second one is the heating rate for a given maximum temperature(T=400◦C).The third one is the dwell time at T=560◦C.3.3.1.Inﬂuence of the maximum temperature reached at constant heating rateTheﬁrst mechanical study carried out at room temperature deals with the inﬂuence of the maximum temperature reached at a given heating rate on the mechanical properties of the AA6061-T6.The maximum temperatures are T=200,300,400,450,500and 560◦C at a heating rate of r=15K/s.The variations of temperature with time for these various thermal loadings are shown in Fig.5. The tensile tests are then conducted at room temperature and the corresponding true stress—logarithmic strain curves are shown in Fig.6.The curves obtained for the heated specimens are compared with the curve obtained for the T6temper without thermal loading (black continuous line).It is found that the thermal loading con-siderably inﬂuences the mechanical properties of the specimens except for a maximum temperature of200◦C for which the curve (not shown in Fig.6)is exactly the same as that of the T6sample. Indeed,the yield stress Rp0.2decreases from278MPa at T=300◦C to 70MPa at T=500◦C.Increasing the temperature further to560◦C, however,does not change the yield stress.Fig.7illustrates this 75%decrease of the yield stress when the maximum temperature is increased from300to500◦C.The measured values are compared to values from the literature[21]for which the maximumtemper-parison of three precipitation states.(a)T6temper;(b)after heating up to300◦C at15K s−1;(c)after heating up to400◦C at15K s−1.All micrographs were taken along a 100 zone-axis of the aluminium matrix.2722 D.Maisonnette et al./Materials Science and Engineering A528 (2011) 2718–2724Fig.4.Modeling of the precipitate distribution for a reached temperature T =300◦C with r avg =2.6nm and L avg =25nm assuming volume fractions of (a)3%and (c)1.6%and comparison with the real precipitate distribution microstructure observed by TEM (b)displayed at the same scale.The volume fraction of 1.6%is obviously closer toreality.Fig.5.Thermal loadings used for the study of the inﬂuence of the reached temper-ature.Fig.6.True stress—logarithmic strain curves for temperatures up to 560◦C.ature has been held during 30min.It shows that the yield stress at ambient temperature is strongly dependent on the peak tempera-ture reached during the thermal loading,without a dwell time at the highest temperature,for peak temperature higher than 200◦C.No data without dwell time at the maximum temperature have been found in the literature.The Young modulus has been also measured for each specimen.It has been measured ﬁrstly at the origin of the stress–strain curve and then during the elastic unloading.A mean value is then calcu-lated.It decreases from 68.7GPa for the T6temper to 65.0GPa for the specimen heated to 560◦C which represents a 5.4%decrease.3.3.2.Inﬂuence of the heating rateThe second mechanical study investigates the inﬂuence of the heating rate on the mechanical properties of the AA6061-T6.The maximum temperature applied here is T =400◦C and the studied heating rates are:r =0.5,5,15,50,and 200K/s.The tempera-ture variation obtained for r =50K/s shows an overshoot of 8◦C which results in a slight decrease of the measured stress.Simi-larly,the temperature of the specimen heated with a heating rate of r =200K/s did not reach T =400◦C but T =362◦C.Consequently,the measured stress for this specimen would be higher than expected.The tensile tests give the true stress—logarithmic strain curves shown in Fig.8.They show that the yield stress Rp 0.2decreasesFig.7.Yield stress variation versus reached temperature from measurements (with-out temperature holding)and from the literature (with a 30min dwell time).D.Maisonnette et al./Materials Science and Engineering A528 (2011) 2718–27242723Fig.8.True stress—logarithmic strain curves for various heating rates up to200K/s. for every heated specimens compared to the T6temper and the lower the heating rate is,the lower the yield stress of the material is.More precisely Rp0.2decreases from170MPa for a heating rate of r=200K/s to96MPa for a heating rate of r=0.5K/s.These values have not been compared with literature since no data dealing with the inﬂuence of the heating rate has been found.3.3.3.Inﬂuence of holding time at560◦CThe last mechanical study accomplished on the material is con-cerned with the inﬂuence of a holding time at high temperature before doing the tensile test at room temperature.This last study compares the mechanical properties of the AA6061-T6after a heat-ing at T=560◦C with and without a dwell time at this temperature. The temperature T=560◦C has been chosen because it is close to the solvus temperature of the␤phase in the␣phase.The chosen dwell time is t=30min and the heating rate is r=15K/s.The mechanical properties obtained for both cases are strictly identical.This result indicates that the dwell time at T=560◦C does not inﬂuence the mechanical properties measured on the tested specimens.4.Discussion4.1.PrecipitationAccording to literature[5–9,13,14],the precipitates which are normally present in the T6temper of the AA6061alloy are very thin and their density is quite high.They are small needles of␤ (or pre-␤ )type.They are oriented following the three 100 matrix directions.Some authors[6,10,22]have carried out a detailed study of the␤ phase.It appears that the X Mg/X Si atomic ratio is very often close to1as reported in Table1.However,other authors[23]man-aged to measure a X Mg/X Si ratio higher than1for GP zones and co-clusters contained in an aged6061.In addition,the observed precipitates are only partially coherent as for the pre-␤ phase. Based on these results,it can be assumed that the precipitates con-tained in the studied reference material are pre-␤ or␤ phases (although the X Mg/X Si atomic ratio measured here to1.29is slightly higher than1).Otherwise,Andersen et al.[6]measured needle pre-cipitates with a size of about4nm×4nm×50nm for the␤ phase and20nm×20nm×500nm for the␤ phase.Furthermore,Don-nadieu et al.[8]measured the size of the precipitates contained in a 6065-T6alloy.They obtained a mean diameter of2.86nm.By com-paring these values to those presented in Sections3.1and3.2it can be assumed that the precipitates contained in the studied AA6061 after heating at400◦C are composed of the␤ phase.On the con-trary,the precipitates contained in the6061-T6and in the6061 after a heating at300◦C are smaller.Therefore,the precipitates are probably remaining␤ precipitates for the6061alloy after heating at300◦C.In addition to that,large intermetallics are visible in the micro-graphs at low magniﬁcation,as shown in Fig.9.The size of the intermetallics ranges from50to300nm.These intermetallics formed during the elaboration of the material do not contribute to the hardening of the alloy.An energy dispersive X-ray spectrometry analysis(EDX)proved that their composition type is(Fe–Cr–Mn–Si) and not(Al–Mg–Si)as for hardening precipitates.The structure of these intermetallics was not investigated further.However,it is important to note that the intermetallics do contain silicon,so that the corresponding quantity will not be available for hardening precipitation.4.2.Mechanical propertiesFig.6showed that the behavior of the material after heating at500◦C is strictly identical to the behavior of the material after heating at560◦C.Thus,it can be assumed that the microstructure is the same in both cases.Furthermore,a tensile test carried out on a specimen heated to560◦C during30min gives exactly the same behavior.This behavior corresponds to the O temper.It is commonly accepted that a long holding time at T=560◦C(solvus temperature of the␤phase in the␣phase)is required to dis-solve the parison of the true stress—logarithmic strain curves obtained with and without dwell time shows that the mechanical properties are identical.This means that the dwell time at T=560◦C does not change the mechanical properties.The microstructure is therefore identical corresponding to the annealed state(or O temper)for which no precipitate is present in the mate-rial.This last result shows that for the heating rate and for the specimens used in this study,it is not necessary to apply a dwell time to reach the O temper.This conclusion is probably not valid in the case of a large structure since the peak temperature at each point within the material would depend on its distance from the closest surface.Another result of this investigation is that the heat-ing rate has an inﬂuence on the mechanical properties.By using a higher heating rate,the O temper could not be obtained without a dwell time.The hardening is due to the precipitates contained within the material.They hinder dislocation glide.For a given volume fraction, hardening is most effective if the precipitates are small(and there-fore more numerous).These small precipitates have been observed by TEM for the T6temper.This microstructure leads to more favor-able mechanical properties than the other investigated states.The behavior observed here is quite close to the one observed by Zain-ul-Abdein et al.[24]on a6056-T4.Then,the microstructure of the specimen heated to300◦C seems to be close to the one observed for the T6temper,which explains the small difference of mechanical properties.If the maximum temperature is further increased,the yield stress Rp0.2decreases signiﬁcantly as shown in Fig.7.The TEM observations show that this decrease is due to a strongly enhanced growth of the precipitates.The volume fraction of the precipitates remains identical so that the precipitate number is decreased.This results in a sharp decrease of the mechanical properties,as high-lighted by the tensile tests.Concerning the study of the inﬂuence of the heating rate,no microstructural observations have been carried out.However,Fig.8 shows a decrease of the mechanical properties for every thermal loading up to400◦C compared to the mechanical properties of the T6temper.This means that the material has encountered a microstructural change for every investigated heating rate.If the heating rate is very low,the microstructural changes as dissolution and growth of precipitates,have more time to occur.Consequently, less precipitates are present(for a constant volume fraction)and the mechanical properties are lower.The Young modulus has been measured and it has been shown that it decreases slightly compared to the T6state when。

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中国电缆工程有限公司(刚果（布）利韦索水电站配套输变电项目)20KV开关柜需要翻译的资料Dossiers à traduire pour la cellule 20KV (projet de transmission et de transformation électrique associé à la centrale hydroélectrique Liouesso de la République du Congo) de China National Cable EngineeringCorporation1.保护跳闸Déclenchement de protection2.减载跳闸Déclenchement de réduction3.保护合闸Enclenchement de protection4.合闸/跳闸转换开关Commutateur pour Enclenchement / Déclenchement5.并列解列转换开关Commutateur pour Intégration / Désintégration6.复归按钮Bouton de reset7.投装置检修Mise en service de l’entretien de dispositif8.闭锁重合闸Réenclenchement de verrouillage9.跳1QF备用Déclenchement de secours 1QF10.跳2QF备用Déclenchement de secours 2QF11.跳3QF备用Déclenchement de secours 3QF12.合3QF备用Enclenchement de secours 3QF13.遥控跳闸Déclenchement de télécommande14.遥控1 Télécommande 115.遥控2 Télécommande 216.遥控3 Télécommande 317.二次接地母排Jeu de barre de mise à terre secondaire18.装置电源空气开关Interrupteur à air de source d’alimentation du dispositif19.控制回路空气开关Interrupteur à air de circuit de contrôle20.照明回路空气开关Interrupteur à air de circuit d’éclairage21.加热回路空气开关Interrupteur à air de circuit de chauffage22.储能回路空气开关Interrupteur à air de circuit de stockage énergique23.电压回路空气开关Interrupteur à air de circuit de tension24.测量电压回路空气开关Interrupteur à air de circuit de tension de mesure25.计量电压回路空气开关Interrupteur à air de circuit de tension de comptage26.直流小母线空气开关Interrupteur à air de petite barre CC27.交流小母线空气开关Interrupteur à air de petite barre CA28.继电器屏板Tableau de relais29.小母线排列图Plan d’arrangement des petites barres30.注:(1)带“*”线采用双芯屏蔽线。

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Agency Problems, Auditing, and the Theory of the Firm：: Some Evidence
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B质量分数对620_℃时效中FB2钢组织和力学性能的影响

第 54 卷第 7 期2023 年 7 月中南大学学报(自然科学版)Journal of Central South University (Science and Technology)V ol.54 No.7Jul. 2023B 质量分数对620 ℃时效中FB2钢组织和力学性能的影响陶学儒1，耿鑫1，姜周华1，李扬1，彭雷朕2(1. 东北大学冶金学院，辽宁沈阳，110819；2. 中国第二重型机械集团有限公司，四川德阳，618000)摘要：通过扫描电镜、拉伸性能测试和硬度测试等对620 ℃长期时效中不同B 质量分数的FB2钢进行组织观察和力学性能分析。

研究结果表明：在FB2钢620 ℃长期时效中，M 23C 6相的平均尺寸随时效时间的延长逐渐增大，其平均尺寸随B 质量分数的增加而逐渐减小；Laves 相在时效1 000 h 后析出，并且随着时效时间的延长不断长大粗化，其平均尺寸随B 质量分数的增加而逐渐减小；BN 夹杂物的析出量随B 质量分数的增加而逐渐增大。

FB2钢的拉伸性能随着时效时间的延长而逐渐减弱，随B 质量分数的增加先增强后减弱，并且在B 质量分数为0.010%时拉伸性能达到最强。

FB2钢的硬度随着时效时间的延长而逐渐减小，随B 质量分数的增加先增大后减小，并且在B 质量分数为0.010%时硬度达到最大。

当B 质量分数由0增加到0.010%时，拉伸性能和硬度的增大是M 23C 6相和Laves 相的平均尺寸的减小所引起的；当B 质量分数由0.010%增加到0.030%时，拉伸性能和硬度的减小是BN 夹杂物析出量的增加所导致的。

为充分发挥钢中B 、N 的强化作用，同时提高FB2钢的高温性能及稳定性，钢中较优的B 质量分数控制在0.010%左右。

关键词：FB2钢；M 23C 6相；Laves 相；BN 夹杂物；拉伸性能；硬度中图分类号：TF7 文献标志码：A 文章编号：1672-7207（2023）07-2642-09Effect of B mass fraction on microstructure and mechanicalproperties of FB2 steel aged at 620 ℃TAO Xueru 1, GENG Xin 1, JIANG Zhouhua 1, LI Yang 1, PENG Leizhen 2(1. School of Metallurgy, Northeastern University, Shenyang 110819, China;2. China Second Heavy Machinery Group Co. Ltd., Deyang 618000, China)Abstract: The organization observation and mechanical property analysis of FB2 steel with different B mass fractions in long-term aging at 620 ℃ were performed by scanning electron microscopy , tensile property test and hardness test. The results show that the average size of M 23C 6 phase gradually increases with the increase of aging time, and its average size gradually decreases with the increase of B mass fraction; the Laves phase precipitates收稿日期： 2022 −09 −13；修回日期： 2022 −11 −02基金项目(Foundation item)：国家自然科学基金资助项目(51974076)；国家重点研发计划项目(2016YFB0300203) (Project(51974076) supported by the National Natural Science Foundation of China; Project(2016YFB0300203) supported by the National Key Research and Development Program of China)通信作者：耿鑫，博士，副教授，从事特殊钢冶金研究；E-mail ：*************DOI: 10.11817/j.issn.1672-7207.2023.07.011引用格式：陶学儒, 耿鑫, 姜周华, 等. B 质量分数对620 ℃时效中FB2钢组织和力学性能的影响[J]. 中南大学学报(自然科学版), 2023, 54(7): 2642−2650.Citation: TAO Xueru, GENG Xin, JIANG Zhouhua, et al. Effect of B mass fraction on microstructure and mechanical properties of FB2 steel aged at 620 ℃[J]. Journal of Central South University(Science and Technology), 2023, 54(7): 2642−2650.第 7 期陶学儒，等：B质量分数对620 ℃时效中FB2钢组织和力学性能的影响after aging for 1 000 h, and grows and coarsens with the increase of aging time, and its average size gradually decreases with the increase of B mass fraction; the precipitation of BN inclusions gradually increases with the increase of B mass fraction. The tensile properties of FB2 steel gradually decrease with the increase of aging time, increasing first and then decreasing with the increase of B mass fraction, and the tensile properties reach the maximum at 0.010% of B mass fraction. The hardness of FB2 steel gradually decreases with the increase of aging time, increasing first and then decreasing with the increase of B mass fraction, and reaches the maximum at0.010% of B mass fraction. When the B mass fraction increases from 0 to 0.010%, the increase of tensileproperties and hardness is caused by the decrease of the average size of M23C6and Laves phases; when the B massfraction increases from 0.010% to 0.030%, the decrease of tensile properties and hardness is caused by the increase of BN inclusions precipitation. In order to give full play to the strengthening effect of B and N in steel, and at the same time improve the high temperature performance and stability of FB2 steel, the better control of B mass fraction in steel is around 0.010%.Key words: FB2 steel; M23C6phase; Laves phase; BN inclusions; tensile properties; hardness当前，大力发展超超临界火电机组是进行煤电机组结构优化的主要方向[1−3]。

A dynamic model of the rolling process. Part I homogeneous model

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P.-H. Hu, K.F. Ehmann / International Journal of Machine Tools & Manufacture 40 (2000) 1–19
3
the model. Freshwater [10] simpliﬁed the equations for roll force, roll torque and roll pressure, without sacriﬁcing accuracy, from the works by Alexander [11] and Venter and Abd-Rabbo [9]. By eliminating the derivative of the yield stress curve, it was shown that both the homogeneous or inhomogeneous solutions of the roll force, etc. can be calculated with equal ease even when the material is rapidly strain hardening, as occurs in the cold rolling processes. Tlusty et al. [12] advanced the model of rolling process dynamics by taking into account the rate of change of the exit strip thickness, which was assumed to be the same as the rate of change of roll gap spacing along the centerline of rolls. Yun [13] and Yun et al. [14–16] further relaxed the assumption that the exit plane coincides with the centerline of rolls, which suggested a new conservation law of mass and an equation for determining the neutral point within the arc of contact. Hu [17] discarded the assumption of constant strip exit velocity and the use of forward and backward slips in velocity calculations, and therefore allowed the model to be more suitable for chatter studies. He also took into account the roll horizontal movement allowing the effects of complicated roll vibrations to be considered. Most of the aforementioned studies fall into the category of static rolling analysis and are not suitable for chatter analysis. The purpose of this paper is to address this problem by introducing an enhanced dynamic process model based on the work of Hu [17], and therefore enable a better study of rolling chatter. Speciﬁcally, the objective is to derive the rolling process model in the form of a transfer function matrix that can be easily combined with a suitable structural transfer function model of the mill to analyze the stability of the process by conventional linear system analysis methods.

国内外石油化工行业“行业标准”对照表----中英文对照!

1)Please find attached the list of international codes and standards to be applied for the design and manufacturing of the whole supply (doc n。

0002-00-00-000-B—G-1-43-002)随函附上全部供应材料设计和制造中应用的国际规范和标准一览表（文件号0002-00—00-000-B-G-1—43—002）.Please kindly confirm compliance；moreover，please confirm that it is already included in your quotation or update accordingly。

请确认符合情况，此外,请确认其已相应包含在贵方报价或更新文件中.2)ASTM / ASME standard Materials with proper certifications (refer to attached material certificate EN 102043.1 samples) shall be provided for the whole supply materials；equivalent Chinese standard material are not accepted by our Client (except the ones listed in the attached doc n. 0002-00-00-000—B—G-1—43-002 section 3）.应为全部材料提供ASTM/ ASME标准材料和适当的认证（参考随附的材料证书EN 10204 3。

1），我们的客户不接受同等的中国标准材料（随附文件号0002-00-00-000-B-G-1—43—002第3节列出的材料除外）。

Fatigue crack growth behaviour and life prediction for 2324-T39 and 7050-T7451 aluminium alloys

Fatigue crack growth behaviour and life prediction for 2324-T39and 7050-T7451aluminium alloys under truncated load spectraRui Bao a,*,Xiang Zhang ba Institute of Solid Mechanics,School of Aeronautic Science and Engineering,Beihang University (BUAA),Beijing 100191,China bDepartment of Aerospace Engineering,School of Engineering,Cranﬁeld University,Bedford MK430AL,UKa r t i c l e i n f o Article history:Received 17September 2009Received in revised form 14December 2009Accepted 21December 2009Available online 29December 2009Keywords:Fatigue crack growth Fatigue load spectra Crack branching Retardation Life predictiona b s t r a c tThis paper presents a study of crack growth behaviour in aluminium alloys 2324-T39and 7050-T7451subjected to ﬂight-by-ﬂight load spectra at different low-stress truncation levels.Crack branching was observed in the higher truncation levels for the 2324and in all truncation levels for the 7050.Mode I crack growth life can be predicted for the 2324alloy by the NASGRO equation and the Generalised Wil-lenborg retardation model.However,quantitative prediction of the fatigue life of a signiﬁcantly branched crack is still a problem.Material properties,test sample’s orientation and applied stress intensity factor range all play dominant roles in the fracture process.Ó2009Elsevier Ltd.All rights reserved.1.IntroductionFor the damage tolerance design of aircraft structures,fatigue tests are required at all structural levels according to the airworthi-ness regulations [1]to support and validate the crack growth life predictions.There are several aspects in both the practical fatigue testing and the development of predictive models.Since a representative service loading spectrum can contain a large number of low-amplitude load cycles that do not cause fati-gue damage but consume unacceptable testing time and cost in the full scale fatigue tests (FSFT),an economic and common practice is to eliminate these low amplitude stress cycles in the test spectrum.Tests and analysis on laboratory specimens are necessary to deter-mine an acceptable load truncation level for the FSFT of a structural component.These laboratory sample tests are used to demonstrate that the elimination of certain low-range loads will not change the characteristic of the crack growth and have little inﬂuence on crack growth life while considering the scale of time saving.The second aspect is the requirement of life prediction tools.Fa-tigue crack growth (FCG)behaviour and life prediction methods under the constant amplitude loads (CAL)have been well estab-lished for commonly used aluminium alloys.The problem of pre-dicting FCG life under the variable amplitude loads (VAL)is still challenging due to the load sequence and load interaction effects [2,3].For simple VAL sequences,rge numbers of CAL cyclesplus occasional tensile overload cycles,or an overload followed by an underload,current prediction methods include the Wheeler [4],the Generalised Willenborg [5,6],and the crack closure models [7,8].These models and a few others have now been implemented in computer packages,such as the AFGROW crack growth analysis code [8].However,the problem of life prediction gets more com-plex when randomly ordered ﬂight-by-ﬂight loading spectrum is used.In most of the cases,the low-amplitude load cycles that tend to be eliminated contribute little to the fatigue crack growth.How-ever,for some circumstances,the elimination of small load cycles might shift the balance between the crack initiation and crack growth phases [9].Moreover,the overload retardation effect is found to be very sensitive to subsequent underload cycles [2,10,11]as well as to the cycle numbers of subsequent lower amplitude stresses [10].Thirdly,the inﬂuence of the low-amplitude load cycles on crack growth rates also depends on the material properties and test sam-ple’s material orientation.In the last four decades,most research efforts in the aircraft applications have been focused on the 2024and 7075aluminium alloys (AA).Consequently,adequate crack growth prediction models are now available [12].In recent years,trend in the aircraft industry is to gradually introduce new versions of the 2000and the 7000series alloys due to their superior mechanical properties.Their performance in terms of FCG life in ﬂight-by-ﬂight loads needs to be investigated.The materials investigated in this study are the AA 2324-T39and AA 7050-T7451,which are widely employed in the current generation of aircraft components.The former is a higher strength0142-1123/$-see front matter Ó2009Elsevier Ltd.All rights reserved.doi:10.1016/j.ijfatigue.2009.12.010*Corresponding author.Tel.:+861082338663.E-mail address:rbao@ (R.Bao).International Journal of Fatigue 32(2010)1180–1189Contents lists available at ScienceDirectInternational Journal of Fatiguejournal homepage:w w w.e l s e v i e r.c o m/l o c a t e /i j f a t i g ueversion of AA 2024-T351and is a high-purity controlled composi-tion variant of 2024,and is mainly applied on the lower wing skin and center wing box components of new commercial transport air-craft.The fracture behaviour and crack growth behaviour of 2324have been widely investigated in recent years for better under-standing and further application of this material [13].Alloy 7050is the premier choice for aerospace applications requiring the best possible combination of strength,stress corrosion cracking (SCC)resistance and toughness.However,it is one of these highly aniso-tropic alloys;consequently,crack growth behaviour along the short transverse direction (L-S)is found to be quite different from that along the long transverse direction (L-T).Nevertheless,the L-S orientated plates have found some applications in the spar caps and stringer webs of machined integral skin–stringer panels.Pro-gress has been made in understanding the crack growth behaviour in L-S orientated AA 7050-T7451plates under CAL at different stress ratios [14,15],in which comparisons of the failure modes be-tween the L-S and T-L plates under truncated loading spectra are also presented.Small crack growth rates in AA 7050-T7451sub-jected to simple load sequences containing underloads are re-ported in [16]to generate constant amplitude crack growth data for use in life predictions.The experimental tests conducted in this study were designed to achieve two objectives:(1)to select a suitable low-load trunca-tion level for the FSFT;(2)to investigate the characteristics of crack growth behaviour under different load spectra with various trun-cation levels.The ﬁrst objective was achieved and reported in [17].The purpose of this paper is to present the investigation ﬁnd-ings towards the second objective,which covers the studies of crack growth behaviour under a ﬂight-by-ﬂight loading spectrum of a civil transport aircraft wing at different small-stress rangetruncation levels and the performance of current predictive models in spectrum loads.2.Experimental procedures 2.1.MaterialsCrack propagation tests were conducted using the middle-crack tension,M(T),specimens made of AA 2324-T39and AA 7050-T7451.The conﬁguration and orientation of the specimens are shown in Fig.1and Table 1.The material data is found in reference [18,19].For alloy 2324,(wt.%),Si 0.1,Fe 0.12,Cu 3.8–4.4,Mn 0.3–0.9,Mg 1.2–1.8,Cr 0.10,Zn 0.25,Ti 0.15,others each 0.05,others total 0.15,aluminium remainder.For alloy 7050,(wt.%),Si 0.12,Fe 0.15,Cu 2.0–2.6,Mn 0.10,Mg 1.9–2.6,Cr 0.04,Zn 5.7–6.7,Zr 0.08–0.115,Ti 0.06,others each 0.05,others total 0.15,balance alu-minium.The mechanical properties are fully deﬁned in [18,19]and presented in Table 2.Crack growth rate and fatigue properties are available for the L-T orientation (refer to Fig.1)for both alloys [20].A total of 66specimens were tested;for each load truncation le-vel six specimens were tested for AA 2324-T39and ﬁve specimens for AA 7050-T7451.2.2.Load spectraThe baseline load spectrum is a ﬂight-by-ﬂight spectrum with each load block simulating 4200ﬂights.The gust and manoeuvres loads are represented by ten load levels ﬂatulating around the mean load corresponding to the 1g ﬂight condition.The ﬂights in each load block are classiﬁed into ﬁve types,stated as A,B,C,D and E,respectively,according to the stress levels.Flight type A is the most severe loading condition occurring only once in each block,whereas ﬂight type E is the least severe occurring 2958times in each block.The ﬁve ﬂight types were arranged randomly within one block except that ﬂight type A was arranged to occur near the middle and in the second half of a block.The taking-off and landing taxiing loads were taken into account by eight equiv-alent loading cycles in each ﬂight.Fig.2a illustrates a loading seg-ment of the baseline spectrum containing the ﬂight types A,B and E.It can be seen that the spectrum is dominated by tension loads.The baseline spectrum (S0)was ﬁltered by removing small-stress range cycles to obtain different truncated spectra,while the taxiing loads during each ﬂight were retained.A 9.82%trunca-Fig.1.Conﬁguration of M(T)specimen and deﬁnition of material orientation.Nomenclature a ,a 0half crack length,half of initial crack length in middle-crack tension,M(T),specimenC ,n ,p ,q material constants in the NASGRO fatigue crack growthrate lawC f 0parameter in AFGROW crack closure model d a /d N crack growth rate E Young’s modulus f parameter in NASGRO equation taking account of thecrack closure effectK ,K max stress intensity factor (SIF),maximum SIF D K ,D K th SIF range,SIF thresholdK crit apparent fracture toughnessN number of cycles in crack growth laws and NASGRO equationN f fatigue crack growth life in terms of ﬂightsR nominal stress intensity factor ratio (R =K min /K max =r -min /r max )SORshut-off Ratio in Willenborg retardation modelTable 1Specimen dimensions (mm)and orientation.Length (L )Width (W )Thickness (t )Half length of the saw-cut (a n )Orientation 2324-T3935098.5 4.54L-T 7050-T745135098.564L-SR.Bao,X.Zhang /International Journal of Fatigue 32(2010)1180–11891181tion level indicates that those load cycles with stress range less than9.82%of the maximum stress range in the S0were removed, while the other parts of the spectrum were kept unchanged.So no matter what the load truncation level is,the mean stress level re-mains to correspond to the1g acceleration.There areﬁve trunca-tion levels resulting inﬁve different truncated load spectra,named as S1,S2,S3,S4and S5,shown in Table3.Fig.2b shows the load sequences ofﬂight type A in S0and S5.2.3.Fatigue testingPre-cracking was accomplished under constant amplitude load of r max=90MPa,R=0.06which resulted in an initial crack length a0of about5.5mm.The FCG tests were subsequently carried out under the aforementioned six load spectra until the half crack length a was greater than24mm.All the tests were conducted using the MTS880fatigue test sys-tem.Specimens were held in a pair of100mm wide hydraulic wedge grips.An observation system consisting of a digital microscope,servo motor and raster ruler was used to record the crack tip position. Incremental crack length measurements were made on both the right and left sides of the front surface of the specimens.The fol-lowing rules were adopted when recording the crack length:(1) if it is an ideal mode I crack,which is perpendicular to the applied loads and propagating along the x-axis,the crack length is the true distance from the symmetric axis of the specimen to the crack tip, Fig.3a;(2)if the crack has deviated from the horizontal x-axis, then the crack length refers to the projected length of the crack on the x-axis,Fig.3b;(3)if the crack has branched,the recorded crack length is the projected length of the longest branch,Fig.3c.3.Prediction method3.1.Review of available crack growth prediction modelsBased on the principle of the linear elastic fracture mechanics (LEFM),FCG rates can be correlated with the stress intensity factor range D K.There are many empirical FCG laws to describe this rela-tionship.Paris law[21]is theﬁrst and most popular,which corre-lates crack growth rate d a/d N with only the D K.During the following decades,modiﬁcations to the Paris law have been devel-oped by taking into account of different factors.For example,the Forman[22]and Walker equations[23]were proposed to encom-pass the mean stress effect.Both the Paris and Walker equations work well for the stable crack growth stage showing good linearity in double logarithm coordinate of d a/d N vs.D K.The Forman equa-tion[22]introduces the parameter of critical stress intensity factor K c therefore can be applied in the prediction of theﬁnal fracture re-gime.Hartman and Schijve[24]suggested a modiﬁed form of Paris law by adding a parameter of stress intensity factor threshold which depended strongly on the alloy and the environment.The NASGRO equation[8]takes account of the inﬂuences of the mean stress,the critical and threshold SIF,and plasticity-induced crack closure by introducing several empirical constants.Most of the empirical constants in the above mentioned crack growth laws are obtained byﬁtting measured crack growth test data under con-stant amplitude stresses.Table2Material mechanical properties.Tensile strength(MPa)Yield strength(MPa)Elongation(%)KI C (plane strain)(MPaﬃﬃﬃﬃﬃmp)2324-T39475370838.5–44(t=19.05–33.02mm) 7050-T7451510441931.9(L-T),27.5(T-L)(t=25.42–50.80mm)Table3Details of the truncated loading spectra.Name of spectrum S0S1S2S3S4S5Truncation level(%)09.8211.7213.9817.1121.36Cycles eliminated in each block(%)026.5646.8762.9573.3578.581182R.Bao,X.Zhang/International Journal of Fatigue32(2010)1180–1189When variable amplitude loading is applied,crack growth behaviour shows more complicated characters.One of the most important factors that should be taken into account is the profound overload retardation effect[2,12].However,this effect is much re-duced when the tension overload is immediately followed by com-pressive underload[2,12].Furthermore,if a load history has peak loads with a long recurrence period,i.e.peak overload cycle is fol-lowed by large numbers of baseline stress cycles,it will result in large retardation in the crack growth curve,while an almost regu-lar crack growth curve may be resulted by a load history which has peak loads with a short recurrence period[10].These two factors were paid more attention in this study,since the loading spectra in this study all contain a tensile overload in theﬂight type A which is followed by a negative underload,and with the increase of load truncation levels,the recurrence periods between the two overload peaks become shorter and shorter.A number of crack growth models have been developed to ac-count for the load interaction effects and thereby enable predic-tions of crack growth lives.Most of the retardation models are based on either the crack tip plastic zone concept or the crack clo-sure argument.Five retardation models are available in the crack growth prediction software AFGROW;they are the Closure model [7,8],the FASTRAN model[25],the Hsu[26],the Wheeler[4]and the Willenborg models[5,6].Each retardation model has one or more user adjustable parameter(s),which are used to tune the model toﬁt the actual test data.Ideally,any parameter in crack retardation models should be a material constant,which is inde-pendent of other variables such as the spectrum sequence and load level.The Generalised Willenborg model is a modiﬁed version of the original Willenborg model.Physical arguments were used to account for the reduction of the overload retardation due to subse-quent underloads.The AFGROW code has adapted the treatment of the underload acceleration effect by using the Chang’s model[8,27] to adjust the overload induced yield zone size.Therefore the effect of compressive stresses after a tension overload is considered.This model is suitable to the overload/underload pattern found in the load spectra used in this study as shown in Fig.2b.The AFGROW Closure model is based on the original Elber’s crack closure concept [7]and developed by Harter et al.[8].This type of crack closure models has been very popular in both the constant and variable amplitude loads because they correlate crack growth rates with the effective stress intensity factor range,which is affected by the applied loads and crack opening displacements;both can be re-lated to the cyclic plasticity effect.The AFGROW Closure model uses a single adjustable parameter(C f0)that is determined at stress ratio R=0in order to‘‘tune”the closure model for a given material. The suggested C f0value by AFGROW for aluminium alloys is0.3[8].3.2.Crack growth and retardation laws used in this studyIn this study,FCG life predictions were accomplished by using the AFGROW computer package[20]and employing the NASGRO equation[8],Eq.(1).Since this equation takes account of the inﬂu-ences of the mean stress,the critical and threshold SIF,and plastic-ity-induced crack closure,it usually gives more accurate predictions provided that the required material constants are available.The material constants used in the NASGRO equation for commonly used aluminium alloys,including2324-T39studied here,are provided in the database of the AFGROW package.d ad N¼C1Àf1ÀRD Kn1ÀD K thp1ÀK maxK critqð1ÞIn order toﬁnd a suitable crack retardation model for further analyses of the truncated load spectra,attempts have been made to predict FCG life from a=5.5mm to22mm under the S0spec-trum using the Generalised Willenborg model and Closure model. The prediction results are shown in Table4.It indicates that both the No-retardation model and the Generalised Willenborg model have achieved good agreement with the test result,whereas the Closure model underestimated the life by13%using the recom-mended C f0=0.3.Prediction is found to be sensitive to the value of parameter C f0.The following crack life predictions are performed by the NASGRO equation(no retardation)and NASGRO equation plus the Generalised Willenborg model.4.Results and discussion4.1.Crack growth morphology4.1.1.AA2324-T39L-T oriented specimenIt has been observed during the experiments that cracks sub-jected to load spectra S0,S1,S2and S3are perfect mode I cracks which areﬂat and straight and perpendicular to the applied loads direction.However,signiﬁcant crack meandering and/or branching are observed when the low-load range truncation is increased to a certain level,i.e.S4and S5,shown in Fig.4.A typical branched crack occurred under spectrum S4is illustrated in Fig.5.It is amaz-ing that the crack always tended to grow away from the centerline of the specimen rather than taking a zigzag route.The crack growth rate dropped signiﬁcantly after the crack had branched.Some evidence has been found for therelationship Fig.3.Recorded crack lengths with respect to different crack morphologies.Table4Predicted FCG life using two different retardation models(spectrum S0,AA2324-T39).Model and parameter NoretardationClosure model WillenborgmodelTestresultC f0=0.3C f0=0.5SOR=3.0aFCGL(ﬂights)12,73911,755551713,72913,495Error(%)–5.6–12.9–59.1 1.7–a SOR=3.0is recommended by AFGROW technical manual[8]for aluminiumalloys.R.Bao,X.Zhang/International Journal of Fatigue32(2010)1180–11891183between the crack growth path change and the peak stress in the ﬂight type A.This will be discussed in Section 4.4.However,branching was not observed immediately after the maximum over-load.It can be deduced that the tension overload had introduced a few secondary cracks in the subsurface of the specimen,which were later observed at the surface of the specimen.The lead crack and the secondary cracks kept growing for a period of loading cy-cles until they were linked up,which has resulted in the observed branched crack.The appearance of the secondary cracks and the linking up process are shown in Fig.6.The ﬁnal failure mode of the branched crack under tension load is almost the same as the perfect mode I crack,showing the typical characteristic of mode I crack in ductile materials,see insert of Fig.5. 4.1.2.AA 7050-T7451L-S oriented specimenCrack turning,meandering,branching and splitting (90°turn)were observed on some specimens whatever the load truncation level was applied as shown in Fig.7a.However,not all the speci-mens showed signiﬁcant crack turning or branching.It is quite dif-ferent from the 2324-T39L-T specimens,in which crack branching occurred only under the spectrum S4and S5.Schubbe also ob-served crack branching and splitting in 7050-T7451L-S oriented specimens [14,15].He has pointed out that signiﬁcant forward growth retardation or splitting is evident at a threshold D K valuein the range of 10–15MPa ﬃﬃﬃﬃﬃm p and a distinct crack arrest point where vertical growth is dominating is found when D K is between18and 20MPa ﬃﬃﬃﬃﬃm p [14].In this study,the D K value corresponding to the peak stress range in ﬂight type A at initial cracklengthFig.4.Crack morphologies under different loading spectra;(a)–(f)are for the S0,S1,S2,S3,S4and S5spectrumrespectively.Fig.5.Crack turning,meandering and branching for 2324-T39(L-T)(the example shown here is under the spectrum S4of low-load range truncation level of17.11%).Fig.6.Appearance of secondary surface cracks and cracks linking up (the example shown here is under the spectrum S5of truncation level about 21.36%):(a)lead crack r ,secondary crack s (b)another secondary crack t ;(c)link-up of the two secondary cracks with the lead crack.1184R.Bao,X.Zhang /International Journal of Fatigue 32(2010)1180–1189a 0=5.5mm is already above 22MPa ﬃﬃﬃﬃﬃm p ,therefore the reason for observed crack branching and splitting is understood,whether or not the load spectrum was truncated.However,it should be men-tioned here that slight crack branching was also observed occa-sionally during the pre-cracking stage with fatigue crack length no more than 0.5mm from the edge of the saw-cut andD K <10MPa ﬃﬃﬃﬃﬃm p ,see Fig.7b.It was hard to get the normal mode I failure strength when per-forming the residual strength testing after the half crack length a had reached 24mm.Longitudinal splitting occurred parallel to the load direction,as shown in Fig.8.4.2.Crack growth livesSince the loading cycle numbers are different in different load spectra corresponding to different truncation levels,FCG life is de-ﬁned as the number of ﬂights,N f ,rather than the number of load cycles N .Initial crack length a 0was 5.5mm for all the specimens.Measured a vs.N f data corresponding to the S0,S2and S4load spectra are shown in Fig.9a and b for the two aluminium alloys,which indicate good linearity in the log-linear coordinate.For the clarity of illustration,measured data for spectra S1,S3and S5are omitted in these ﬁgures.They do follow the same trend and similar scatter range.Fig.9c and d present the best ﬁtted curves of the test data with respect to all the loading spectra using exponential linear least square method,a ¼Ae BN fð2Þwhere,A and B are ﬁtting parameters.Since a 0=5.5mm,ﬁnd A =5.5.Crack growth retardation due to overload effect are not obvious in this ﬁgure for spectra S0,S1,S2,and S3.The signiﬁcant retardation found in the S4and S5spectra tests was partially caused by the crack branching described in Section 4.1and partially by the removal of large numbers of load cycles at these two higher trunca-tion levels.4.3.Prediction of crack growth livesCrack growth life predictions were performed using the AF-GROW code.Predicted a –N f curves for AA 2324-T39are shown in Fig.10.The loading spectra and specimen conﬁguration used in the prediction are the same as those used in the experimental tests.In the ﬁgures,‘‘No Retardation”means no load sequence effect was considered;‘‘Willenborg”demotes the Generalised Willenborg model.Following observations can be made:(1)For S0,S1,S2and S3,i.e.load range truncation level of 0%,9.82%,11.72%and 13.98%of the maximum load range,the predicted lives agree well with the test results.(2)Under the spectra S4and S5,17.11%and 21.36%truncation levels,measured crack growth lives are much longer than the predicted by Willenborg model.Such differences in the model and measurement cannot be related to the overload retarda-tion effect alone.The main reason is the occurrence of signiﬁcant crack meandering and branching under these two loading spectra,as mentioned in Section 4.1,which slow down the lead crack growth rate signiﬁcantly.This kind of crack growth retardation mechanism is very different from that due to the overload induced plastic zone effect.Crack path deviation was not observed in the tests subjected to load spectra S0,S1,S2and S3.Hence,the FCGlifeFig.7.Crack morphology of the L-S oriented 7050-T7451specimens:(a)crack branching and splitting during propagation under spectrum S0,(b)crack branching during pre-cracking under constant amplitudeloads.Fig.8.Final splitting failure of a L-S oriented 7050-T7451specimen under static residual strength test.R.Bao,X.Zhang /International Journal of Fatigue 32(2010)1180–11891185predictions are fairly accurate,even though the same tensile over-loads exist in these spectra as in the S4and S5.(3)Predicted lives obtained by the ‘‘No Retardation”model and ‘‘Willenborg”model do not differ from each other too much;both are located within the scatter band of the test data.This is mainly due to the overload pattern:an underload is immediately following the overload,see Fig.2b,reducing the retardation effect.Considering the preferred conservativeness in practical applications,NASGRO equation with-out overload retardation is applicable for such kind of load spec-trum investigated in this study with low-stress range truncation levels no higher than 14%of the maximum stress range.Since the crack growth rate data in terms of d a =d N –D K is not available for the 7050-T7451L-S orientation in the AFGROW package,FCG life prediction for this material under spectrum loads was not con-ducted.Schubbe published some d a =d N –D K crack growth data for AA 7050-T7451L-S orientation under constant amplitude loads at different stress ratios in [14].Attempts have been made to use these data and the Harter T-method to predict crack growth lives for 7050-T7451under spectrum loads.However,the d a =d N –D K curves in [14]have a characteristic divergent sinusoidal trend ofgrowth when D K >10MPa ﬃﬃﬃﬃﬃm p ,where the growth mode alter-nates between arrested forward growth and splitting,or arrested vertical growth and continuing forward progression.This crack growth data cannot be used in the crack growth life prediction with the AFGROW,because there is no crack growth model that can take account of such sinusoidal trend of crack growth.4.4.Crack growth rateIt has been mentioned in Section 4.3that the ‘‘No Retardation”option in AFGROW gives good FCG life predictions under the load spectra S0,S1,S2and S3.However,when the crack branching or splitting occurred under S4and S5,the observed signiﬁcant crack growth retardation is not caused by the overload induced yield zone effect;hence it cannot be predicted by these retardation mod-els in AFGROW.Another point is that the crack branching was not observed immediately after the maximum stress in the block.Since it is difﬁcult to observe the overload effect from these a –N f curves,the crack growth rate data may shed light on the effect immedi-ately after each overload.Attempts have been made to ﬁnd expla-nations for the relationship between crack growth retardation and tensile overloads.Fig.11shows the measured d a /N f –N f curves for the 2324-T39L-T and 7050-T7451L-S specimens under different load truncation levels.Locations of the peak loads in the ﬂight A are marked by the vertical lines.The effect of these peak loads on crack growth rate can be observed.These crack growth rate vs.ﬂights curves show periodic changes in both aluminium alloys.Following obser-vations can be made:(1)The occurrences of crack retardation fol-low the maximum tension overload regularly in each load block.(2)Retardation is more signiﬁcant at higher truncation levels,S4and S5,than that at lower truncation levels,S0,S1,S2and S3.(3)Crack growth retardation in 2324-T39L-T specimens is more1186R.Bao,X.Zhang /International Journal of Fatigue 32(2010)1180–1189。

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重油粘度的新关联参数

New Correlating Parameter for the Viscosity of Heavy Crude Oils Rashid S.Al-Maamari,†Omar Houache,†and Sabah A.Abdul-Wahab*,‡Departments of Petroleum&Chemical Engineering and Mechanical&Industrial Engineering, College of Engineering,Sultan Qaboos Uni V ersity,P.O.Box33,Al-Khod123,OmanRecei V ed June29,2006.Re V ised Manuscript Recei V ed August4,2006A new correlating parameter(CAPI)for heavy crude oils was developed.In this parameter,the API(American Petroleum Institute)oil gravity was corrected using a factor comprising compositional fractions(saturates, aromatics,resins,and asphltenes contents of the heavy crude oil).It was found that relating viscosity to CAPI was more representative than relating the viscosity to the API measurement ing this new correlating parameter for the heavy crude oils considered in this study,two very different tendencies,defining a limiting value of15,were observed.The viscosities of oils found under the limiting value of15were very sensitive to small changes in CAPI.An Omani heavy crude oil that showed higher viscosities compared to other crudes of similar API was found to be normal in terms of viscosity behavior when CAPI was used.In addition,crude oil viscosity could be predicted with more accuracy using this correlating parameter at different temperatures.IntroductionMeasurement/estimation of heavy oil viscosity is required in predicting the easiness of fluid flow,selecting a production approach,and predicting oil recovery.Numerous correlations have been proposed in the literature for the estimation of fluid viscosity(e.g.,dead-oil viscosity(µod),gas-saturated oil viscosity (µob),and undersaturated oil viscosity(µo))based on measured fluid properties.1-36In the majority of cases,these correlations indicated a good prediction of crude oil viscosity for the oils from which they were derived.However,when used with other crude oils from other regions,these correlations are,in most cases,not accurate and certain modifications are needed to obtain acceptable viscosity predictions.36-38*Corresponding author.E-mail:sabah1@.om.†Department of Petroleum&Chemical Engineering.‡Department of Mechanical&Industrial Engineering.(1)Braden,W.B.A viscosity-temperature correlation at atmospheric pressure for gas-free oils.J.Pet.Technol.1966,1487-1490.(2)Beggs,H.D.;Robinson,J.R.Estimating the viscosity of crude oil systems.J.Pet.Technol.1975,27(Sept),1140-1141.(3)Viscosity in technical data book-petroleum refining.Data Book; American Petroleum Institute:Washington,D.C.,1978;Chapter11.(4)Amin,M.B.;Maddox,R.N.Estimating viscosity vs temperature. Hydrocarbon Process.1980,59,31-38.(5)Baltatu,M.E.Prediction of the liquid viscosity of petroleum fractions. Ind.Eng.Chem.Process De V.1982,21,192-195.(6)Ikram,H.Characterization of Saudi Arabian crude oil fractions with emphasis on viscosity behaviour.MS Thesis,KFUPM University,KSA, 1982.(7)Mehrotra,A.K.;Svrcek,W.Y.Correlations for properties of bitumen saturated with CO2,CH4and N2,and experiments with combustion gas mixtures.J.Can.Pet.Technol.1982,21,95-104.(8)Khan,M.A.B.;Mehrotra,A.K.;Svrcek,W.Y.Viscosity models of gas-free athabasca bitumen.J.Can.Pet.Technol.1984,23,47-53.(9)Annual Book of ASTM Standards;ASTM(American Society for Testing and Materials):Philadelphia,PA,1987;Designation D-341,pp 149-153.(10)Johnson,S.E.;Svrcek,W.Y.;Mehrotra,A.K.Viscosity prediction of athabasca bitumen using the extended principle of corresponding states. Ind.Eng.Chem.Res.1987,26,2290-2298.(11)Khan,S.A.;Al-Marhoun,M.A.;Duffuaa,S.O.;Abu-Khamsin, S.A.Viscosity correlations for Saudi Arabian crude oils.Prepared for presentation at the Fifth SPE Middle east Oil show,Manama,Bahrain,Mar 7-10,1987;SPE15720.(12)Beg,S. A.;Amin,M. B.;Hussain,I.Generalized kinematic viscosity-temperature correlation for undefined petroleum fractions.Chem. Eng.J.1988,38,123-136.(13)Mehrotra,A.K.;Svrcek,W.Y.Properties of cold lake bitumen saturated with pure gases and gas mixtures.Can.J.Chem.Eng.1988,66, 656-665.(14)Al-Blehed,M.;Sayyouh,M.H.;Desouky,S.M.Correlation estimates Saudi crude oil viscosity.Oil Gas J.1990,88(10),61-62.(15)Mehrotra,A.K.Modeling the effects of temperature,pressure,and composition on the viscosity of crude oil mixtures.Ind.Eng.Chem.Res. 1990,29,1574.(16)Mehrotra,A.K.A generalized viscosity equation for pure heavy hydrocarbons.Ind.Eng.Chem.Res.1991,30,420-427.(17)Mehrotra,A.K.Modeling temperature and composition dependence for the viscosity of diluted bitumens.J.Pet.Sci.Eng.1991,5,261-272.(18)Miadonye,A.;Singh,B.;Puttagunta,R.V.One-parameter correla-tion in the estimation of crude oil viscosity.Pap.SPE1992,26206.(19)Puttagunta,V.R.;Miadonye,A.;Singh,B.Viscosity temperature correlation for prediction of kinematic viscosity of conventional crude. Trans.Inst.Chem.Eng.1992,70,627-631.(20)Miadonye,A.;Puttagunta,V.R.Prediction of the viscosity of crude oil fractions from a single mun.1993,122, 195-199.(21)Puttagunta,V.R.;Miadonyea,A.;Singh,B.Simple concept predicts viscosity of heavy oil and bitumen.Oil Gas J.1993,Mar1,71-73.(22)Puttagunta,V.R.;Singh,B.;Miadonye,A.Correlation of bitumen viscosity with temperature and pressure.Can.J.Chem.Eng.1993,71,447-450.(23)Singh,B.;Miadonye,A.;Puttagunta,V.R.Modeling the viscosity of Middle-East crude oil mixtures.Ind.Eng.Chem.Res.1993,32,2183-2186.(24)Singh,B.;Miadonye,A.;Puttangunta,V.R.Heavy oil viscosity range from one test.Hydrocarbon Process.1993,12(5),157-162.(25)Singh,B.;Miadonye,A.;Huang,S.S.;Srivastava,R.;Puttangunta, V.R.Estimating temperature effects on viscosity of Saskatchewan heavy oils.Fuel Sci.Technol.Int.1994,12(5),693-704.(26)De Ghetto,G.;Paone,F.;Villa,M.Pressure-volume-temperature correlations for heavy and extra heavy oils.Prepared for presentation at the1995SPE International Heavy Oil Symposium,Calgary,Alberta, Canada,June19-21,1995;SPE30316.(27)Giambattista,De G.;Villa,M.Pressure-volume-temperature correlations for heavy and extra heavy oils.Prepared for presentation at the International Heavy Oil Symposium,Calgary,Alberta,Canada,June 19-21,1995;SPE30316.(28)Petrosky,G.E.;Farshad,F.F.Viscosity correlations for Gulf of Mexico crude oils.Prepared for presentation at the Production Operations Symposium,Oklahoma City,OK,Apr2-4,1995;SPE29468.(29)Wakabayashi,T.Viscosity correlation with specific gravity and molecular weight of crude oil fractions.Fuel1997,76(11),1049-1056.(30)Bennsison,T.Prediction of heavy oil viscosity.Presented at the IBC Heavy Oil Field Development Conference,London,Dec2-4,1998.2586Energy&Fuels2006,20,2586-259210.1021/ef0603030CCC:$33.50©2006American Chemical SocietyPublished on Web09/08/2006A general correlation is nearly always found between oil viscosity and gravity.Therefore,oils are usually characterized by their API (American Petroleum Institute)oil gravity.How-ever,viscosity -gravity correlations often fail to yield heavy oil viscosity data with sufficient accuracy for engineering appli-cations.They also cannot be used on small samples.39(31)Carlson,R.M.K.;Pena M.M.;Boduszynski,M.M.;Rechsteiner,C.E.;Shafizadeh,A.S.G.;Henshaw,P.C.Geochemical -Viscosity correlations among heavy crude oils of the San Joaquin Valley,California.In 7th UNITAR hea V y crude and tar sands international conference proceedings [CD-ROM];Information Center for Heavy Hydrocarbons,United Nations Institute for Training and Research:New York,1998;Paper 1998.203,p 24.(32)Miadonye,A.;Puttagunta,V.R.Modeling the viscosity-temperature relationship of Nigerian Niger-Delta crude petroleum.Pet.Sci.Technol.1998,16(5&6),627-638.(33)Dindoruk, B.;Christman,P.G.PVT properties and viscosity correlations for Gulf of Mexico oils.Prepared for presentation at the 2001SPE Annual Technical Conference and Exhibition,New Orleans,LA,30Sept -3Oct 2001;SPE71633.Figure 1.Plot of kinematic viscosity versus API at 25°C.Figure 2.Plot of kinematic viscosity versus API at 50°C.New Parameter for Hea V y Crude Oils Energy &Fuels,Vol.20,No.6,20062587Available data for an Omani heavy crude oil (OHCO)of 16°API and 1700cP in situ viscosity showed that the fluid viscosity follows the expected trends with both temperature and pressure.However,based on data available in the open literature,it appears that the OHCO fluid has a higher viscosity compared to other oils of similar or slightly lower APIs and oils with similar or higher asphaltene contents.Although oil viscosity is not always in a direct relationship with gravity,the comparisons are somewhat troubling and it is still not clear why the OHCO viscosity is relatively higher.Therefore,the viscosity -API correlation is the focus of this paper.A new correlating parameter (CAPI)or corrected API that can be used for heavy oil characterization is presented.The reported results are the product of analysis of many heavy oils data collected from the open literature for various heavy oil fields around theworld.Figure 3.Oil API gravity vs viscosity under reservoir conditions.Each point represents an oilfield.At any single API gravity value,there maybe variation of 2orders of magnitude in viscosity.40Figure 4.Plot of viscosity versus temperature at the same API of 16(data taken from the USA heavy oil database 41).Figure 5.Plot of log -log kinematic viscosity versus log of the absolute temperature at different API values (data taken from Henshaw et al .42).2588Energy &Fuels,Vol.20,No.6,2006Al-Maamari et al.MethodologyTo understand clearly the relationship between the API and viscosity,an extensive literature search on heavy oil viscosity from other regions in the world was carried out.Hence,the results reported in this work are the product of the analysis of many heavy oils data collected for various heavy oil fields from the open literature.29,39-47The oils used in the present analysis cover an API range of 8.7-25.83.Distinctive parameters that have been considered are crude oil gravity (API)and compound class distributions (i.e.,saturated hydrocarbons (Sa),aromatic hydrocarbons (Ar),resins (Re),and asphaltenes (As)).Experimental data for an Omani heavy crude oil have been used to validate the findings of this work.Results and DiscussionFigures 1and 2show the kinematic viscosity versus API gravity for different crude oils at 25and 50°C,respectively.It can be seen that the viscosity remains fairly low across the 25-20°API gravity range but increases below 18°API.It has been noticed that some heavy oils show anomalous behavior with regard to their API.A wide range of viscosity values for the same API were observed.40,41At any single API gravity value,there may be variation of 2orders of magnitude in viscosity (Figure 3).This behavior can be clearly seen in Table 1and Figure 4.For the considered 17crude oils with the same API of 16,a wide range of viscosities can be encountered at the same temperature.The relative variation in viscosity values could be as high as 775%.Figures 5and 6show that viscosity versus temperature has different slopes which means that there could be cases where two different oils (say,oil 1and oil 2)with API 1less than API 2will have µ1greater than µ2at one temperature,µ1equal to µ2at another temperature,and even µ1less than µ2at othertem-Figure 6.Kinematic viscosity vs temperature for a group of oils.Their API gravity appears in parentheses.39Figure 7.Mass fraction of Sa,Ar,Re,and As versus API (data taken from the Enviromental Technology Centre database 43).Table 1.Different Viscosities at the Same API of 16(Data from theUSA Heavy Oil Database 41)API T (°C)viscosity (cp)%relative change1632.0620130011035.53393400.338.014029611146022943.014542019049.0888********.5470475160.01289642105775New Parameter for Hea V y Crude Oils Energy &Fuels,Vol.20,No.6,20062589peratures.This indicates that serious errors are introduced by the assumption that the viscosity of a heavy oil is only a function of API.Due to their complexity,the composition of crudes is not expressed in terms of pure components.Instead,their composi-tion is commonly described as percentages of saturated hydro-(34)Shanshool,J.;Hashim,E.T.Kinematic Viscosity -temperature correlation for undefined petroleum fraction of a wide boiling range.J.Pet.Technol.2001,19(13&14),257-268.(35)Elsharkawy,A.M.;Hassan,S.A.;Hashim,Y.S.Kh.;Fahim,M.A.New compositional models for calculating the viscosity of crude oils.Ind.Eng.Chem.Res.2003,42,4132-4142.(36)Al-Marhoun,M.A.Evaluation of empirically derived pvt properties for Middle East crude oils.J.Pet.Sci.Eng .2004,42,209-221.(37)Barrufet,M.A.;Dexheimer,e of an automatic data quality control algorithm for crude oil viscosity.Fluid Phase Equilib .2004,219,113-121.(38)Naseri,A.;Nikazar,M.;Dehghani,S.A.M.A correlation approach for prediction of crude oil viscosities.J.Pet.Sci.Eng .2005,47,163-174.(39)Hernandez,M.E.;Vives,M.T.;Pasquali,J.Relationships among viscosity,composition,and temperature for two groups of heavy crudes from Eastern Venezuelan .Geochem.1983,4(3/4),173-178.Figure 8.Plot of viscosity versusCAPI.Figure 9.Plot of log(log(viscosity))versus API.2590Energy &Fuels,Vol.20,No.6,2006Al-Maamari et al.carbons,aromatic hydrocarbons,resins,and asphaltenes.Since these groups of compounds change in composition from one crude to another,they are usually not used to predict the vis-cosity of crudes.Figure 7relates the API values of the studiedoils to their Sa,Ar,Re,and As content.In general,these plots indicate a decrease in API with an increase in Sa and decreases in Ar,Re,and As.It is interesting to note the relationship between viscosity and the (Sa/(Ar +Re +As))ratio multiplied by the API,the new correlating parameter (CAPI)(Figure 8).(40)Smalley, C.Heavy oil and viscous oil.In Modern Petroleum Technology:Volume 1:Upstream ;Dawe,R.Ed.;John Wiley &Sons Ltd.:New York,2000;Chapter 11.(41)USA Heavy Oil Database,International Centre for Heavy Hydro-carbons /default.htm.(42)Henshaw,P.C.;Carlson,R.M.K.;Pena,M.M.Evaluation of geochemical approaches to heavy oil viscosity mapping in San Joaquin Valley,California.Prepared for presentation at the 1998SPE Western Regional Meeting,Bakersfield,CA,May 10-13,1998;SPE 46205.(43)Environmental Technology Centre (ETC).Oil properties database.http://www.etc.ec.gc.ca or /databases/spills_e.html.(44)Wu,W.;Chen,J.Characteristics of Chinese Heavy Crudes.J .Pet.Sci.Eng .1999,22,25-30.(45)Pirela,L.Influence of Time in the Viscosity Determination of Heavy Crudes and Their Mixtures.Presented at the Third International Conference on Heavy Crudes and Tar sands,UNITAR/UNDP Information Centre for Heavy Crude &Tar Sands,New York,USA,1985;HCTS/CF.3/8.7,559A-559T.(46)Srinivasan,M.;Watkinson, A.P.Fouling of Some Canadian Crude Oils.Presented at the ECI Conference on Heat Exchanger Fouling and Cleaning:Fundamentals and Applications,Watkinson,P.,Mu ¨ller-Steinhagen,H.,Malayeri,M.R.,Eds.;Santa Fe,NM,USA,2003;Paper 26.(47)Pereira,P.How to Extend Existing Heavy Oil Resources through Aquaconversion Technology.Presented at the World Energy Council,2004.Figure 10.Plot of log(log(viscosity))versus CAPI.Table 2.Ranking of Heavy Oils Taken from Henshaw et al .42by the New Correlating Parameter (CAPI)kinematic viscosity,mm 2/sfield API CAPI 40°C 50°C 60°C 70°C 100°C 135°C 177°C Cymric 8.7 1.6923280642022601000145.532.610.37Cymric9.4 1.952238059902050890126.931.210.18Midway Sunset 10.4 2.011219036701380610103.926.39.43Midway Sunset 10.5 2.0395303200122054091.524.28.72Cymric 9.2 2.2091702950117054097.724.48.71Cymric 10 2.22130203720135058094.223.38.01Cymric 9.7 2.3193403100115051084.821.17.59Cymric 10.2 2.449420292011205108623.48.62Cymric 10.9 2.454400152064031061.617.4 6.62Coalinga 10.3 2.7992702830108048079.722.27.99Coalinga 9.7 2.8098902950110049078.3227.83Cymric 11.7 2.8020708003701904213.6 5.48Kern River 11.9 3.41336012505502805817.1 6.86Kern River 13.1 3.58184074034018041.713.7 5.52Kern River 12.5 3.603050114051026054.316.3 6.87Kern River 12.3 3.75217089042022052.115.8 6.49Kern River 14.5 4.0371033017010026.610 4.4Kern River 14.1 4.176002801509024.97.4 4.15Kern River 13.4 4.84115049024013033.612.9 4.92Coalinga14.45.343801901006019.17.33.4New Parameter for Hea V y Crude Oils Energy &Fuels,Vol.20,No.6,20062591It can be seen that the viscosities of oils under the limiting value of ∼15are very sensitive to small changes in CAPI.Further-more,it is also interesting to note that the Omani heavy crude oil viscosity can be predicted from this graph at any temperature.Unfortunately,no complete consistent data is available to explain the existence of this limiting value.Figure 9shows a plot of viscosity versus API.Looking at this figure,it can be seen that Omani heavy crude oil viscosity does not follow the general trend of other crude oils.However,when the viscosity is plotted versus CAPI,(Sa/(Ar +Re +As))×API,the Omani heavy crude oil seems to behave like other heavy oils (Figure 10).This new method of ranking heavy oils was applied to data taken from Henshaw et al .,42and the results are shown in Table 2and Figure 11.It seems that heavy oils are better characterized by this correlating parameter than by the API gravity alone,as is usually done.ConclusionConsiderable errors may be introduced when the viscosity of heavy oils is estimated from general viscosity trends and the API gravity.The method of ranking heavy oil using API gravity was not always positional terms such as the percent saturates,aromatics,resins,and asphaltenes can reasonably correct these apparently anomalous behaviors.In a plot of viscosity versus the new correlating parameter (CAPI),two very different tendencies,defining a limiting value of 15,were observed.The viscosities of oils found under the “limiting value”of 15were very sensitive to small changes in CAPI.On the basis of the above points,heavy oil that showed higher viscosity compared to oils of similar API was found to be normal when CAPI was used.EF0603030Figure 11.Plot of log(log(viscosity))versus log(temperature)for data taken from Henshaw et al .422592Energy &Fuels,Vol.20,No.6,2006Al-Maamari et al.。