实测并建立了55NiCrMoV7钢的热物性参数数据库和CCT曲线,基于ABAQUS软件建立了不同冷却介质淬火的热力耦合模型。模拟了大型压力机模座油冷和水冷两种淬火过程,获得了温度场和应力场的演化规律。结合模座上不同位置的冷却速度和CCT曲线预测了工作层的组织状态,并预测了模座上的应力分布。结果表明:采用完全油冷方式将在工作层内产生上贝氏体组织,力学性能无法达到使用要求;而完全水冷方式则可在工作层内得到下贝氏体,但在模座内倒角处存在极大的淬裂危险。在此基础上,提出了双液淬火的热处理工艺,模拟结果显示,水冷30min后转入油冷既可保证工作层理想的组织状态,同时也避免了模座局部位置的淬裂危险。
Abstract
Database of thermal-physical parameters and CCT curves of 55NiCrMoV7 steel were firstly obtained by experimental study.Based on the commercial FEM software ABAQUS,the models of oil-quenching and water-quenching for a large press die holder were established separately,the temperature and stress evolution were calculated for each process.Combined with the cooling rates of each node and CCT curves of 55NiCrMoV7,the final microstructure and stress distribution on the die holder were predicted.According to the FEM results,upper bainite can be obtained in the surface layer by oil quenching,while lower bainite can be obtained under water cooling condition.However,cracks are easily generated in the inner chamfer by water quenching because of the severe stress concentration.On basis of the analysis,double quenching process was proposed to avoid crack and obtain lower bainite,the simulation results show that 30min water-cooling before oil-cooling is favorable toward safe production and optimizing the microstructure of the die holder.
关键词
压力机模座 /
淬火 /
有限元模拟
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Key words
press die holder /
quenching /
finite element method(FEM)
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中图分类号：
TG151.2
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参考文献
[1] 赵昌盛.模具材料及热处理手册[M].北京:机械工业出版社,2008.
[2] 赵品,谢辅洲,孙振国.材料科学基础教程[M].哈尔滨:哈尔滨工业大学出版社,2003.
[3] ZHANG Z,DELAGNES D,BERNHART G.Microstructure evolution of hot-work tools during tempering and definition of a kinetic law based on hardness measurements[J].Materials Science and Engineering A,2004,380(1-2):222-230.
[4] ZHANG Z P,QI Y H,DELAGNES D,et al.Microstructure variation and hardness diminution during low cycle fatigue of 55NiCrMoV7 steel[J].Journal of Iron and Steel Research,International,2007,14(6):68-73.
[5] SIMSIR C,GUR C H.3D FEM simulation of steel quenching and investigation of the effect of asymmetric geometry on residual stress distribution[J].Journal of Materials Processing Technology,2008,207(1-3):211-221.
[6] LI H P,ZHAO G Q,HE L F.Finite element method based simulation of stress-strain field in the quenching process[J].Materials Science and Engineering A,2008,478(1-2):276-290.
[7] HIBBITT.ABAQUS/Standards User's Manual Version 6.9[M].New York:Karlsson & Sorensen Inc,2009.
[8] ESI GROUP.SYSWELD User's Manual Version 2008[M].2008.
[9] 弗兰克 P 英克鲁佩勒,大卫P德维特,狄奥多尔L伯格曼,等.传热与传质基本原理[M].北京:化学工业出版社,2007.
[10] 孙明月,李殿中,李依依,等.大型船用曲轴曲拐弯锻过程模拟与实验研究[J].金属学报,2005,41(12):1261-1266.
[11] BAKHTIARI R,EKRAMI A.The effect of bainite morphology on the mechanical properties of a high bainite dual phase(HBDP)steel[J].Materials Science and Engineering A,2009,525(1-2):159-165.
[12] LEE S J,PARK J S,LEE Y K.Effect of austenite grain size on the transformation kinetics of upper and low bainite in a low-alloy steel[J].Scripta Materialia,2008,59(1):87-90.
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