29 2-2-E-连铸关键设备再制造技术研究与应用_OK_

Research and Application of Remanufacturing Technology in Continuous Casting Core EquipmentsHou Fengyan, Ren Qiaohua, Gaojinyan,Wang qingxinShanghai Baosteel Industry Technological Services Co. Ltd.Abstract：The importance of the application of remanufacturing technology in continuous casting core equipments for high-efficient and green-steel developing model are described . This paper is mainly introduces the research work of the failure mode of continue casting mold and continue casting roller, surface treatment and structure-design technique in Baosteel.The practice shows that the remanufacturing engineering system, with its advanced surface technology,design and management methods, made a continuous technical improvement on steel facilities, such as prolonging their life time and retirement period,improving the grade and added value,will get a good social and economical benefit.Key Words: Continue Casting Equipment, Surface Technology, Remanufacture, Analytic technology0 IntroductionSteel industry is toward the development of high-efficient and green-steel model,As an important link in production,the model of continuous cast also change toward the direction of a advanced economic model with high economic benefit,less resources consumption and minimizing environmental pollution. In 2011,the output of casting billet in our country is about 620 million tons. This means that the condition of continue casting equipment is very important to keep the the process in statistical control and the quality of products.Therefore,the stabilization and long-period of continue casting core equipment,such as continue casting mold,Segment,electromagnetic Stirring roll and electromagnetic brake,is the important method to realize high-efficient and green-steel developing model.Continuous casting equipments often need to bear the high-temperatureoxidation,thermal fatigue and stress deformation ,chemical corrosion caused by liquid steel and slag atmosphere, as well as friction and wear generated by the operating such as casting and traction .Poor working environment requires and casting equipment need high mechanical strength, Poor working conditions require continuous casting equipment needs to have a high-mechanical strength, good thermal conductivity, good wear resistance and corrosion resistance .Remanufacturing engineering,with advanced surface technology,design and management methods,made a continuous technical improvement on steel facilities,such as prolonging their life time and retirement period,which not only reduces energy consumption and environmental pollution caused in the manufacturing process of new product, a significant reduction in the costs of waste products, pollution of the environment and disposal of industrial solid waste, energy and materials to reduce pollution and create more profit, while reducing equipment maintenance and downtime, improve production efficiency. Visible, manufacturing engineering,its system functions exactly the same direction of development of the modern steel industry, is to make outstanding contributions to the development of the modern steel industry.363364The maintenance costs of mould copper plate and continue casting roll account for about eighty percent of the entire continuous casting equipment,this article will focus on the application and its research work of remanufacturing of continuous casting mould copper and continuous casting roll.1 remanufacturing of continuous casting copper plate1.1 continuous casting copper plate failureThe working environment of continuous casting mold has the following characteristics: Continued friction between the billet shell and copper, high temperature oxidation,chemical and electrochemical corrosion of liquid steel,chemical and electrochemical corrosion of various slag atmosphere, the static pressure of molten steel and molten steel heat conduction. In general, the working conditions of the continuous casting mold is a high temperature, high corrosion and high wear, high heat flux of four harsh environment.In such working conditions, the copper mold will result the following failure modes(Figure1) such as copper surface wear, copper surface scratch, copper surface corrosion, copper surface hot cracking and copper fan-shapeddeformation.Figure 1 Failure Mode of CCM1.2 surface treatment of continuous casting mouldModification surface of the copper plate by using electroplating,thermal spraying and high temperature self-propagating method, through the surface treatment of the copper mould copper plate re-manufacture is not just the size of copper plate was repaired, and have high strength, high toughness,excellent corrosion resistance,wear resistance and thermal fatigue resistance, Thermal fatigue resistance of the copper plate surface functional coating,make the life of the copper mould greatly extend and improve the product grade, technology content and added value, but also improves the efficiency of the steel production, saving energy and material.It has been gradually formed several major continuous casting mold surface coating technology such as Ni plating,Ni-Fe plating,Ni-Co plating,Ni-Co plating,Co-Ni plating and the erosion properties of thermal sprayed alloy from the initial plating Cr in Baosteel,the product performance also gradually improved.It can be seen from Figure 2, the amount of production of electroplated Co-Ni and thermal spraying mold is relatively high,reached 20 million tons or even up to 30 million tons,have excellent properties.Electroplated Co-Ni and thermal spray alloys is the most representative of the mold surface treatment of the new technology in Baosteel.Figure 3 shows the hardness changes of the coating after heat treatment for the temperature of 100、200,300,400,500 and 600 ℃,the hardness of sprayed and the Co-Ni coatings basically remain unchanged with increasing temperature.Its hardness is much higher than other coatings. Visible, both spray coating and the Co-Ni coating have good thermal stability.365Figure 2 service life and surface treatment of CCMThe friction and wear properties of the coating can be seen from Figure 4,Co-Ni coating not only has a very low coefficient of friction, and wear-resistant performance.硬度(H V )热处理温度(℃×1hr)0.00.20.40.60.81.0磨损速率(m g /h r )镀层种类平均摩擦系数Figure 3 Influence of coatings hardness by heat treatment Figure 4 Wear characters of coatingsWith the rapid development of the iron and steel industry, ever-increasing demands on the performance of the mold surface, in order to adapt to the requirements of this, Baosteel is aimed at ceramics(nano) composite plating technique,the long-side copper thermal spray technology and new alloy plating technology research and development,and the results shows that these new technologies have good development prospect.1.3 structural design for CCMIn the remanufacturing process of continuous casting mold,not the application of the best surface coating can improve the life of the product.Deformation of copper,thermal cracks,abnormal wear of copper,these issues can not be solved only rely on a single coating optimization.Therefore,we must consider the overall optimization of the mold when promote the development of mold copper coating materials.By using the finite element analysis technology to research the structure of copper mold and conditions of service,a variety of optimization design of the mold was applied, including the cooling structure of the mold,mold taper,continuous casting production process parameters,mold copper plate coated with layer in the form of specifications,not only can solve the various problems generated by the copper mold during use,and also to optimize the production process conditions.Figure 5 shows micro-cracks and local spalling was found in top mouth of mould of a continuous casting mold copper plate and the service life expectancy is only 595 heats.Analysis revealed that temperature at the lever of the molten steel in mold copper is higher than the normal temperature of 40℃ through analysis of thermal desorption.we366propose solutions of reduce the temperature of copper plate by improve the structure of water channel, and the detailed design and pre-verified by analytical technology and prospective validation,finally after cooling structure optimization design of the mould life in creased to 1088 heats.某连铸线铜板上口产生微裂纹和局部剥落热解析分析提出解决措施：改水槽钢液面温度过高果良好裂纹、镀层剥落过钢量：595炉过钢量：1088炉Figure 5As shown in figuire6,it is easy to produce crack in the slab corner when coolant water tanks in the copper plate corner of a bloom continuous casting mold. But the service life of sealing ring in the copper corner is very short.Through the temperature field of the copper thermal desorption of copper, We remanufacturing of copper behind the back plane and set a cooling tank in the corner position of the back plane, So both slab slow cooling in the mold to avoid cracks slab corner, and achieve the purpose of cooling the copper corner seals, which avoid the sealing parts being burnt and referrals. Improve mold life online for more than three times.Figure 62 continue casting roller remanufacture2.1 failure of continuous casting rollerThe main reason for failure in continuous casting rollers is thermal fatigue damage, corrosion and wear. Continuous casting rollers continuous contact with the high temperature slab,the temperature distribution in the367direction of the torus and the vertical torus cycle of the roller are non-uniform, hot and cold shock effect has always been the role of the roller, and also by the role of slab bulging force and the static pressure of the alternating mechanical stress.A common effect of mechanical stress and thermal stress damage result in thermal fatigue of the casting roll.High temperature oxidation occurs when continuous casting rollers is in the work condition,Hydrofluoric acid generated by the large number of fluorine ions and hydrogen ions in the continuous casting mold fluxes caused by acid etching effect, it is easy for the roller surface to produce high temperature corrosion.mechanical stress is very high when the high temperature slab contact with the semi-solidification and the solidification of high temperature slab.so the oxide scale will cause serious wear on the surface of the slab.2.2 failure handling of CC rollerSurfacing is a main surface treatment technology in continuous casting rollers remanufacturing process.In order to maximize the superiority of the welding technology, high-quality, high efficiency, low dilution rate is an important research direction of the casting roll at home and abroad.Baosteel has carried out the roll material and heat treatment process, new surfacingmaterials and welding technology, stiff dough coating material and spraying process,continuous casting rolls failure mechanism analysis research.After laboratory tests ,pilot test and in-kind trial system development process, developed for large-scale production of continuous casting rolls with a new roller body material and surfacing technology.It would be better to use out arc for roller welding stainless in theory,for out arc surfacing without preheating before casting roll, the relatively small heat surfacing, surfacing without the need to do after the annealing treatment, so the casting roll deformation the relatively small amount of material organization and the surfacing layer containing nitrogen, so it has good corrosion resistance and abrasion resistance, but the out arc welding wire cost is relatively high. Recent we test wire submerged arc welding wire replacement arc in Baosteel mechanical , while the out arc surfacing process, the same alloy containing nitrogen in the surfacing layer material organization, it also has good corrosion resistance and anti-abrasion resistance, and much lower than the open arc welding wire submerged arcwelding wire cost.2.3 structure design for continue casting rollerOver the years has been repeated with a simple continuous casting rollrepair work in this industry like Surfacing repair →reuse →Surfacing repair again, until the casting roll scrap, such are pair should only be casting roll service life is shorter than the last, and repair costs increase year by year.In 2008, we proposed a new type of continuous casting roll structure - near the outer wall of the cooling casting roll. Continuous casting roll body cars off the assembly line needs Surfacing 50-60mm, and milling the cooling water spiral groove, and then put on theseamless steel tubes, both ends of the weld, welding stainless steel in seamless steelpipe, as shown in Figure 7 below.Figure 7We can see that the cooling water holes of the original design center cooling structure ofthe maximum temperature of the roller: 261.5 , average temperature: 239 ° C thermal desorption temperature field of continuous ℃casting rollers. Figure 8. Highest near the outer wall of the cooling structure of the new design roller temperature: 152.4 ° C,average temperature: 116 . Figure 9. ℃368Remanufacturing it on-line life of the casting rolls to 2-3 times, not only significantlyreduces the cost of maintenance of the continuous casting machine, also substantiallyimprove the operating rate of the continuous castingmachine.图8 图9 3 conclusionIt is very important to remanufacturing technology development and application for continuous casting core equipment, practice efficiency, green steel model of development model.Practice shows that with the advanced surface technology and advanced remanufacturing engineering system, design and management methods, made a continuoustechnical improvement on steel facilities, such as prolonging their life time and retirement period, improving the grade and added value ,which has a good economic and social performance.。