新型热作模具钢5CrNiMoVNb的热变形行为研究  

Investigation on hot deformation behavior of new hot work die steel 5CrNiMoVNb

作　　者：胡志强 王开坤[2] 詹建明 师红旗 HU Zhiqiang;WANG Kaikun;ZHAN Jianming;SHI Hongqi(School of Information Engineering,Suqian University,Suqian 223800,Jiangsu,China;School of Material Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]宿迁学院信息工程学院,江苏宿迁223800 [2]北京科技大学材料科学与工程学院,北京100083

出　　处：《钢铁研究学报》2023年第4期443-453,共11页Journal of Iron and Steel Research

基　　金：国家重点研发计划资助项目(2017YFB0701803);宿迁市科技计划资助项目(K202137)。

摘　　要：为了研究热作模具钢5CrNiMoVNb的热变形行为,利用Gleeble3800热模拟试验机进行单道次热压缩实验,获得了应变速率为0.001~0.1 s^(-1)和变形温度1030~1230℃条件下的高温流变应力曲线。应用双曲正弦函数构建了与应变有关的材料本构模型并验证,并基于动态材料模型构建了三维功率耗散图和三维失稳图,将二者叠加得到典型应变下的热加工图。结果表明,所有变形条件下的高温流变应力曲线均呈现典型动态再结晶特征,并且由于奥氏体基体析出强化相含量、动态再结晶体积分数的影响,流变应力随变形温度的降低或应变速率的增大而增大。基于5CrNiMoVNb钢的本构模型计算的流变应力值与实验值的相关性系数为0.9927,较高的相关性系数表明建立的高温流变应力模型能够比较准确地预测合金的流变应力。此外,根据不同条件下的三维功率耗散图和三维失稳图可知,随着应变的增大,功率耗散峰值区向中温、高应变速率区域扩散,热变形失稳仅容易出现在低应变、低变形温度和高应变速率区域。真应变为0.8时,最佳的加工工艺参数范围为:变形温度为1080~1200℃,应变速率为0.01~0.1 s^(-1)。To study the hot deformation behavior of the hot work die steel 5CrNiMoVNb,the single-pass hot compression experiments were carried out with a Gleeble3800 thermal simulation testing machine.The true stress-true strain curves were obtained for strain rates between 0.001 and 0.1s^(-1) and deformation temperatures from 1030-1230℃.A strain-dependent material constitutive model was constructed and verified by using the hyperbolic sine model.Based on the dynamic material model(DMM),a three-dimensional power dissipation map and a three-dimensional instability map are respectively constructed,and three processing maps at typical strains were finally obtained.The results show that the high temperature flow stress curves under all deformation conditions show typical dynamic recrystallization characteristics.And the flow stress increases with the decrease of the deformation temperature or the increase of the strain rate due to the influence of the content of precipitation strengthening phase distributed on austenite matrix and the volume fraction of dynamic recrystallization.The flow stress correlation coefficient between the calculated value based on the constitutive model and the experimental value of 5CrNiMoVNb steel is 0.9927.The high correlation coefficient indicates that the established flow stress constitutive model can accurately predict the flow stress of the steel.In addition,according to the three-dimensional power dissipation map and three-dimensional instability map under different deformation conditions,it can be seen that with the increase of strain,the power dissipation peak region spreads to the middle temperature and high strain rate region,and thermal deformation instability only occurs in the regions with low strain,low deformation temperature and high strain rate.When the true strain is 0.8,the optimum deformation temperature and strain rate interval are 1080-1200℃and 0.01-0.1s^(-1).

关 键 词：热变形行为 高温流变应力 本构模型 热加工图 热作模具钢 

分 类 号：TG142[一般工业技术—材料科学与工程]