长期时效对一种新型镍基合金的组织及持久性能的影响

第27卷　第5期
2006年　10月
材　料　热　处　理　学　报
TRANS ACTIONS OF M ATERIA LS AND HE AT TRE AT ME NT
V ol .27　N o .5October
2006
长期时效对一种新型镍基合金的组织及持久性能的影响
崔　彤1
,　王继杰2
,　王　磊1
,　杨洪才1
,　赵光普
3
(1.东北大学材料与冶金学院,辽宁沈阳　110006;　2.沈阳航空工业学院材料工程系,辽宁沈阳　110034;3.北京钢铁研究总院,北京　100081)
摘　要:研究一种新型镍基合金在750、800、850℃长期时效(500-2000h )过程中的组织变化及其对750℃Π510MPa 持久性能的影响。

用扫描电子显微镜对合金显微组织及持久断口进行观察。

结果表明:
在750-800℃时效该合金有针状T CP 相(拓扑密排相)析出,随其析出量的增加,合金基体的强度降低,合金持久断裂趋于从沿晶断裂转为穿晶断裂;800℃、850℃经不同时间时效处理,1000h 处持久强度最低,这与γ′相尺寸变化有关;随时效温度的升高,试验合金750℃Π510MPa 的持久激活能降低,持久强度下降。

关键词:镍基合金;　长期时效;　T CP 相(拓扑密排相);　持久性能;　持久激活能
中图分类号:TG 13213;　TG 14211 文献标识码:A 文章编号:100926264(2006)0520056204
收稿日期:　2005211214;　修订日期:　2006203230
基金项目:　国家“十五”科技攻关项目(冶N o 10050390B );辽宁省博士启动基金项目(20051010);辽宁省航空专项基金项目(2005400607)
作者简介:　崔　彤(1968—
),男,讲师,博士,主要从事高温合金等高性能材料领域的研究工作,发表论文20余篇,E 2mail :ct114928@
1631com 。

目前航空燃气涡轮发动机较多使用含铁的镍2铁
基合金或不含铁的镍基合金,这种材料需要承受高温下氧化、气体腐蚀及复杂应力等的综合作用,对材料的强度及稳定性有较高要求。

镍2铁基G H4169(Inconel718)合金是当前普遍使用的盘材合金,其使用温度不超过650℃。

随着航空事业的发展,对发动机设计的技术指标也随之提高,新合金需要在700℃以上安全使用,由于铁基合金已不能满足这一要求,镍基合金成为研究的重点。

由该合金的成分(表1)可见该合金是以γ′相为主要强化相兼有碳化物强化和基体的固溶强化,并且兼有较多的钨、钼等难溶金属元素。

随着合金元素的复杂,合金的长期时效处理
将对其内部的相、组织及高温性能产生影响[124]。

合金的高温持久性能是评价该合金高温下长期使用的一项重要指标,是合金能否在高温下长期使用的关键[5,6]。

为此,本文开展了这方面的研究工作,为复杂镍基合金在高温下的使用提供依据。

1　试验材料和方法
试验合金试样取自双真空熔炼,经1200℃均匀
化处理后,锻造开坯轧成直径21mm 棒材。

合金的化学成分如表1。

表1　试验合金的化学成分(w t %)
T able 1　Chemical composition of the tested alloy(w t %)
C Cr C o M o W Al T i B M g Ni 0.06
19.0
11.0
8.00
3.00
1.60
3.35
0.05
0.01
bal
试验合金经标准热处理后,再进行长期时效处
理。

标准热处理制度为1080℃×4hAC (空冷)+760℃×16hAC (空冷)。

长期时效热处理制度见表2(试验合金长期时效处理后采用空冷)。

表2　长期时效热处理工艺
T able 2　Long 2term aging heat treatment conditions
N o.Process 1750℃×500h 2750℃×1000h 3
750℃×1500h 4750℃×2000h 5800℃×500h 6800℃×1000h 7800℃×1500h 8850℃×500h 9850℃×1000h 10
850℃×1500h
将热处理后的合金加工成标准δ5高温持久拉伸
性能试样。

在C MT 5105电子万能试验机上测定合金
在750℃Π510MPa 持久拉伸性能。

再取金相样观察金相组织变化,腐蚀剂为3g CuS O 4+80ml HCl +40ml C 2H 5OH 。

采用SSX 2550型扫描电子显微镜对合金显
微组织、高温持久断口进行观察分析。

2　试验结果
211　试验合金时效处理后组织变化
图1(a )为试验合金标准热处理后的扫描电镜照
片,图1(b )为750℃经1500h 处理后的组织照片。

分析可见,经标准处理后在奥氏体晶界分布着链条状碳化物并且尺寸也较大。

通过合金相分析结果表明,合金热处理后主要强化相是γ′相、初生MC 、M 23C 6和M 6C
[5,6]。

当时效时间延长到1500-2000h 后在晶内
或晶界附近出现片状T CP 相,当温度升到800℃时
T CP 相减少、晶界变粗、晶内出现网状碳物,850℃以后T CP 相消失,由图1(c )、1(d )可见。

212　长期时效后合金持久性能及断口形貌
经过标准热处理后分别经750、800和850℃长期时效处理后合金在750℃Π510MPa 下的持久性能如图2所示。

其结果表明,在750℃时效时,在时效时间1500h 前随着时效时间的延长,750℃Π510MPa 下的持久性能基本呈线性增加,而后快速降低,在2000h 时达到最低值。

而此时合金的延性却很高,见图2(a )。

800℃和850℃长期时效处理后合金在750℃Π510MPa 下的持久性能随着时间的延长呈下降趋势,
而延性对于800℃下,1000h 时为最低;850℃下,500h
时为最低。

图1　合金长期时效后的SE M 显微组织
Fig 11　SE M micrographs of different sam ples treated by long 2term aging
(a )1080℃×4h 空冷+760℃×16h ,空冷(标准热处理);(b )标准热处理+750℃×1500h ,空冷(N o 13);
(c )标准热处理+800℃×1500h ,空冷(N o 17);(d )标准热处理+850℃×1500h ,空冷(N o 110)
(a )normal heat treatment :1080℃+4h ,air cooling (AC )+760℃×16h ,AC ;(b )normal heat treatment +750℃×1500h ,AC (N o 13);
(c )normal heat treatment +800℃×1500h ,AC (N o 17);(d )normal heat treatment +850℃×1500h ,AC (N o 110
)
图2　不同温度下时效对合金750℃Π510MPa 下的持久性能的影响
Fig 12　750℃Π510MPa stress 2rupture properties of alloy after long 2term aging at different tem peratures
(a )750℃;(b )800℃;(c )850℃
7
5第5期崔　彤等:长期时效对一种新型镍基合金的组织及持久性能的影响
图3　合金长期时效后部分典型持久断口及纵剖面形貌
(a)(标准热处理+750℃×500hAC)断口形貌;(b)(标准热处理+750℃×500hAC)纵剖面形貌;
(c)(标准热处理+750℃×2000hAC)断口形貌;(d)(标准热处理+750℃×2000hAC)纵剖面形貌
Fig13　750℃Π510MPa stress2rupture fractographs and micrographs of longitudinal section of the alloy after long2term aging
(a)fractograph of sam ple N o11;(b)m orphology of longifudinal section of sam ple N o11;
(c)fractograph of sam ple N o14;(d)m orphology of longifudinal section of sam ple N o14
图3a为合金经标准热处理后,再经750℃×500hAC处理后,750℃Π510MPa下的持久断口形貌,从中可见,韧窝较深,撕裂带较多,有明显的撕裂纹络,从其纵剖面(图3b)可见,合金的断裂为混合型断裂,裂纹的走向既有沿晶扩展也有穿晶扩展,T CP相析出不明显,与其有较高的持久强度相对应。

图3c为经标准处理后,再经750℃×2000hAC处理后,750℃Π510MPa下的持久断口形貌,从中可见,韧窝较浅,没有明显的撕裂纹络,从其纵剖面(图3d)可见,合金的断裂以穿晶断裂为主,因此合金的强度与塑性主要受到长期时效后晶内γ′相长大的影响,同时发现,裂纹萌生于晶界及T CP相并向晶内扩展。

由此使合金的强度降低并导致塑性的增加。

3　分析与讨论
高温持久强度与蠕变激活能关系:高温合金高温下的持久强度是合金的重要力学性能指标,其应力、温度及一定应力条件下持久时间的关系和蠕变性能规律是一致的,在高温一定条件下持久断裂的过程包括:位错运动的聚集、裂纹源的形成以及扩展达到临界条件、持久裂纹迅速扩展导致最终断裂。

因此高温下持久裂纹形成过程也是由热激活开始,而裂纹扩展路径与合金相及组织有密切关系。

对持久性能而言,持久断裂时间与变形速率一般呈倒数关系[5],即当应力为常数σ=k时,则存在:
1
t
=Ae-Q RT(1) t2持久断裂时间;R2气体常数;Q2蠕变激活能; T2试验时间。

lg t-Q
2.3R
1
T
=-C(2) 其中C=lg A。

表3　试验合金长期时效过程中750℃Π510MP a下
持久激活能Q(kJΠmol)
T able3　750℃Π510MP a stress2rupture activation energy of
the alloy during long2term aging
Aging tem peratureΠ℃Aging timeΠh QΠ(k JΠm ol)
500430.50
7501000421.82
1500422.00
500420.19
8001000408.04
1500409.19
500408.13
8501000405.75
1500406.89
这样一定应力条件下log t与1
T
呈直线关系,其斜
率为Q
2.3R
,即可得出一定应力条件下持久应变激活
85材　料　热　处　理　学　报第27卷
能Q 。

根据G H4586A 合金在510MPa Π750℃持久实验结果,求出的经不同温度和时间时效合金的持久应变激活能见表3。

表3结果表明,时效温度提高可以降低持久过程的激活能,而时效时间的延长由500h 到1000h ,激活能降低明显,而1000h 到1500h 变化不明显。

这是因
为试验温度范围内随着M 23C 6、
μ相和σ相的析出,Cr 、M o 、W 、C o 等固溶强化元素由γ基体转入到析出
相中,导致在γ基体中的浓度降低,固溶强化作用降
低,使高温持久强度降低[729]。

另外,热处理时间对高
温持久强度的影响与γ′相尺寸的变化有关。

4　结论
1)试验合金在750-800℃时效有片状T CP 相析
出,随其析出量的增加,使合金基体的强度降低,合金
持久断裂趋于从沿晶断裂转为穿晶断裂;
2)在800、850℃经不同时间时效处理,1000h 处持久强度最低,这与γ′相尺寸变化有关;
3)随时效温度的升高,试验合金750℃Π510MPa 的持久激活能降低,持久强度下降。

参
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5第5期崔　彤等:长期时效对一种新型镍基合金的组织及持久性能的影响
transmission election microscopy and an images analysis approach. The results show that the addition of Mn and S i obviously restrains the growth of cementite particles in the severely cold2rolled pearlite during subsequent annealing,and im proves the distribution evenness of spheroidized cementite particle sizes.The addition of Mn is m ore effective to refine the cementite particles than that of S i.The coarsening kinetics equations of cementite particles for the alloys of Fe2018C,Fe2018C21S i and Fe2018C21Mn are d=18614t01195,d= 9015t0.205and d=85.9t0.166in turn.
K ey w ords:alloying element;pearlite;cementite;cold rolling; annealing
E ffect of annealing process on microstructure and mech anical properties of severe plastic deform ation pearlitic steel wire
T U Y i2y ou1,LI U X iang2liang1,J I ANG Jian2qing1,C AI Lei2,BI AN Jian2chun2(1.Department of Material Science and Engineering, S outheast University,Nanjing210096,China; 2.Jiangsu Fasten G roup,Jiangyin214433,China)
T rans M ater Heat T reat,2006,27(5):43～45,figs3,tabs2,refs11. Abstract:E ffect of annealing process on microstructure of SWRH72A steel wire under severe plastic deformation were investigated by TE M and XRD.The XRD analysis shows that severe plastic deformation causes partial of cementite decom position and diss olution of carbon into ferrite up to0134at%.Cementites form which distribute dispersively in matrix when the annealing tem perature reachs200-300℃, resulting in increasing the strength of wire.Annealing tem perature reachs400℃,the strength of wire decreases sharply,but the plasticity enhances significantly.
K ey w ords:pearlitic steel;severe plastic deformation;cementite re2 diss olution;annealing
I nvestigation on dynamic recrystallization of FGH96powder metallurgy superalloy
LI U Jian2tao1,ZH ANG Y i2wen1,T AO Y u1,LI U G uo2quan2,H U Ben2fu2(1.High T em perature Material Institute,Central Iron and S teel Research Institute,Beijing100081,China;2.School of Material Science and Engineering,University of Science and T echnology Beijing,Beijing100083,China)
T rans M ater Heat T reat,2006,27(5):46～50,figs8,tabs0,refs6. Abstract:The dynamic recrystallization(DRX)behaviour of as2HIP FG H96PΠM superalloy at1070℃～1170℃with strain rate at5×10-4s-1～2×10-1s-1was studied by means of is othermal com pression test on a G leeble21500thermal mechanical simulator.The experiment results show that curves of true stress(σ)2true strain(ε) at higher strain rate(
ε≥2×10-2s-1)are the type of dynamic recrystallization and are the type of dynamic recovery at lower stain rate(
ε≤2×10-3s-1).Although tem perature,strain rate and strain are im portant factors which affect grain refining during hot deformation,grain size during DRX is mainly determined by strain rate to s ome degree.The grain size( D)and Z ener2H ollm on parameter (Z)during DRX process obey the following equation:ln D=71617-010134ln Z.By means of w orking hardening rate2strain curves deduced from the stress2strain curves,the steady strain(εs)is determined,and als o the diagram of DRX for FG H96PΠM superalloy is given.
K ey w ords:FG H96PΠM superalloy;hot deformation;dynamic recrystallization
Precipitation of microalloyed carbonitride and its strengthening mech anism in low carbon steels containing Nb and Mo
C AO Jian2chun1,2,Y ONG Qi2long2,LI U Qing2y ou2,S UN X in2jun2
(1.Department of Materials and Metallurgy Engineering,K unming University of Science and T echnology,K unming650093,China;2. Institute of S tructural Materials,Central Iron and S teel Research Institute,Beijing100081,China)
T rans M ater Heat T reat,2006,27(5):51～55,figs3,tabs7,refs12. Abstract:The distribution,m orphology,com position,crystal structure and particle size of microalloyed carbonitride precipitates in hot rolled Nb2M o steels were examined by XRD,TE M and E DS.The results reveal that the fine and uniformly distributed MC type carbonitrides containing M o and Nb with NaCl type structure precipitate in the steels,in which the atomic ratios of M o to Nb in01081Nb20114M o steel and0117Nb20112M o steel are0141and0122,respectively. Meanwhile,the mass percent of the fine particles(<10nm)in the tw o Nb2M o steels is5814%and6611%,respectively,and the corresponding yield strength increments reach to17913MPa and 25717MPa.The mechanism of the precipitation is discussed.
K ey w ords:microalloying carbonitride;niobium;m olybdenum; precipitation;precipitation strengthening
Microstructures and high2temperature properties of a new Ni2 b ased superalloy after long2term aging
C UI T ong1,W ANG Ji2jie2,W ANG Lei1,Y ANG H ong2cai1,ZH AO G uang2pu3(1.C ollege of Materials and Metallurgy,N ortheastern University,Shenyang110006,China; 2.Department of Materials Engineering,Shenyang Institute of Aeronautical Engineering, Shenyang110034,China; 3.Central Iron and S teel Research Institute,Beijing100081,China)
T rans M ater Heat T reat,2006,27(5):56～59,figs3,tabs3,refs9. Abstract:The relationship between high2tem perature stress2rupture properties and microstructure of a Ni2base alloy used in spacecrafts was investigated after long2term aging at tem peratures of750℃, 800℃and850℃,respectively.The microstructure and stress2rupture fractographs were als o analyzed by means of SE M.The results indicate that T CP(T opologically Close2Packed)phase,a harm ful phase to Ni2 base alloy,precipitated during aging at tem peratures from750℃to 800℃,and its quantities and sizes increase with the aging time increasing that make the strength of matrix of alloy decrease and the stress2rupture behavior be changed from grain boundary rupture to grain interior.750℃Π510MPa stress2rupture strength of the alloy aged at tem peratures of800℃and850℃for1000h was the lowest, respectively because of the changes ofγ′phase size.The higher of aging tem perature is,the lower of750℃Π510MPa stress2rupture
Ⅲ
第5期M AI N T OPICS,ABSTRACTS&KEY W ORDS
activation energy will be,s o that stress2rupture strength of the alloy is decreased.
K ey w ords:Ni2base alloy;long2term aging;T CP(T opologically Close2 Packed)phase;stress2rupture property;stress2rupture activation energy
Study on mech anical properties and microstructure of 10Cr9Mo1VNb steel after high temperature aging
CH ANG T ie2jun1,G ONG Zheng2chun2,LI M ing2fei1,W ANG Y u1 (1.School of Mechanical and E letric Engineering,Harbin Engineering University,Harbin150001,China;2.Harbin Boiler C om pany Ltd, Harbin150046,China)
T rans M ater Heat T reat,2006,27(5):60～63,figs5,tabs2,refs6. Abstract:The mechanical properties and microstructure of 10Cr9M o1VNb steel aged at high tem perature were investigated.The results show that the stability of microstructure of10Cr9M o1VNb steel at high tem perature is excellent and no significant change of strength is observed for the steel aged at625℃for10000h com pared with that of the as2received steel.The ultimate tensile strength only decreases about115%for the steel after the aging treatment.I t is concluded that larger am ount of M23C6and MC carbides precipitated in the steel during aging is the main reas on of its excellent high tem perature properties based on the TE M observation and E DS analysis.
K ey w ords:10Cr9M o1VNb steel;high tem perature ageing; mechanical properties;microstructure;M23C6phase
Corrosion beh avior of316L stainless steel in the combination action of sulfate2reducing and iron2oxidizing b acterias
X U C ong2min1,ZH ANG Y ao2heng1,CHE NG G uang2xu1,ZH U Wen2 sheng2(1.X i’an Jiaotong University,X i’an710049,China;
2.Research and T echnology Center of Lanzhou Oil Refinery Factory, PetroChina C om pany Limited,Lanzhou730060,China)
T rans M ater Heat T reat,2006,27(5):64～69,figs6,tabs2,refs13. Abstract:The corrosion behavior of316L SS in the combination action of aerobic I OB and anaerobic SR B is olated from cooling water system in oil refinery was investigated using bacterial analyses, electrochemical measurement,scanning electron microscopy(SE M) and energy dispersive spectrum(E DS).The results show that the E corr,E pit and E rp of316L SS decrease significantly for the presence of SR B and I OB,in com paris on with those observed in the sterile medium for the same exposure time interval.E corr of316L SS in the sterile medium remained virtually unchanged with exposure time, indicating that pitting attack did not occur.H owever,micrometer2 scale pitting is observed on the316L SS sur face in the combination action of SR B and I OB.The combination action of SR B and I OB dem onstrates higher corrosion rates than that in the sterile medium. The biofilm observed by biology microscope is neither integrity nor com pact.The metabolic activity of bacteria under biofilms increases the corrosion damage degree of the passive film,and accelerates the pitting corrosion.I t is suggested from the present study that SR B and I OB in in fluencing pitting corrosion of316L SS is highlighted.K ey w ords:sulfate2reducing bacteria(SR B);iron2oxidizing bacteria (I OB);316L stainless steel;biofilm passive film;pitting corrosion
E ffect of multiple thermomech anical heat treatment on microstructure and mech anical property of near2alph a TA15 titanium alloy
W ANG Bin,G UO H ong2zhen,Y AO Z e2kun,ZH AO Jing,ZH AO Zhang2long,ZH ANG M ing2yuan(School of Material Science and Engieering,N orthwestern P olytechnical University,X i’an710072, China)
T rans M ater Heat T reat,2006,27(5):70～72,figs2,tabs3,refs9. Abstract:The refining effect of multiple therm omechanical heat treatment on the microstructure of the near2alpha T A15titanium alloy was studied.The results indicate that the multiple therm omechanical heat treatment can markedly refine the microstructure of T A15alloy, and the mechanical properties of T A15alloy can be im proved.In single phase region,the high2tem perature therm omechanical heat2 treatment can refineβgrains and the microstructure of fine2acicular martensiteα′and meta2stableβphase is obtained.The fine2acicularα+βphase diss olved from martensiteα′and meta2stableβphase is further refined by low2tem perature therm omechanical heat treatment. The mechanical properties of the T A15alloy at room tem perature and high tem perature are im proved in s ome extent by the multiple therm omechanical heat treatment.At the same time,the creep rupture strength of the alloy increases obviously,but its elongation at room tem perature drops slightly.The multiple therm omechaincal heat treatment is an effective process for refining microstructure and im proving mechanical property of titanium alloy.
K ey w ords:T A15titanium alloy;multiple therm omechanical heat2 treatment;microstructure;mechanical property
Study on structure and electrochemical properties of CO2 corrosion scales on P110steel corroded at high temperature and pressure
LI Chun2fu1,2,W ANG Bin2,DAI Jia2lin2,W ANG Hu2,ZH ANG X ian2ju2,LUO Ping2ya1(1.S tate K ey Laboratory of Oil and G as Reserv oir G eology and Exploitation(S outhwest Petroleum University), Chengdu610500,China; 2.C ollege of Materials Science and Engineering of S outhwest Petroleum University,Chengdu610500, China)
T rans M ater Heat T reat,2006,27(5):73～78,figs10,tabs1,refs11. Abstract:C orrosion tests of P110steel was conducted in the extraction liquid of oil field for4to144hours by simulating the supercritical fluid condition of C O2(35MPa,160℃)exited in deep well.The structure and electrochemical behavior of the corrosion scale were analyzed by SE M、XRD、XPS and EIS.The results indicate that when the P110steel contacts with the extraction liquid contained4m ol% C O2,the corrosion scale rapidly forms within4to8hours,and up to 48hours,it is consisted of fine FeC O3crystal grains.During the period of48to144hours,the FeC O3scale gradually changes into a fine com pound scale consisted of(Fe,Ca)C O3,Fe2CaC O3and
Ⅳ材　料　热　处　理　学　报第27卷。