热作模具钢4Cr5MoSiV1的热变形行为及本构模型修正

Thermal deformation behavior and modification of constitutive model of 4Cr5MoSiV1 hot working die steel

借助Gleeble-3500热模拟试验机和光学显微镜研究热作模具钢4Cr5MoSiV1在变形温度为750~1050℃、应变速率为0.001~0.1 s^-1条件下的热变形行为及显微组织特征。结果表明,4Cr5MoSiV1钢的流变应力随温度升高而降低,随应变速率升高而增大;动态再结晶在低应变速率与高变形温度下更易发生;得到4Cr5MoSiV1钢在该变形参数下的热变形激活能为704.73 k J·mol^-1,建立了应变量为0.2时的Arrhenius高温本构模型,本构参数的拟合相关系数在95%以上。针对传统本构模型的不足,构建了耦合应变量的改进型本构模型,并对本构参数进行了3次、6次及9次拟合。结果表明,9次拟合的相关系数超过97.94%,可以更准确地预测4Cr5MoSiV1钢的热变形抗力。

The thermal deformation behavior and microstructure characteristics of 4 Cr5 MoSiV1 hot working die steel under deformation temperature of 750-1050℃and strain rate of 0.001-0.1 s^-1 were studied by Gleeble-3500 thermal simulator and optical microscope.The results show that the flow stress of 4 Cr5 MoSiV1 steel decreases with the increase of temperature and increases with the increase of strain rate.Dynamic recrystallization is more likely to occur at low strain rate and high deformation temperature.The thermal deformation activation energy of 4 Cr5 MoSiV1 steel with these deformation parameters is 704.73 k J·mol^-1.The Arrhenius high temperature constitutive model was established at the strain of 0.2.And the fitting correlation coefficient of the constitutive parameters is above 95%.In view of the shortcomings of the traditional constitutive models,an improved constitutive model coupling strain was constructed,and three,six and nine times fitting of the constitutive parameters were carried out.The results show that the correlation coefficient of the nine times fitting exceeds 97.94%,and it can predict the thermal deformation resistance of 4 Cr5 MoSiV1 more accurately.