52CrMoV4弹簧钢热变形行为的本构模型

Constitutive Model of Hot Deformation Behavior of 52CrMoV4 Spring Steel

基于导向臂用52CrMoV4弹簧钢的热锻及热压变形工艺研究,采用Gleeble-3500型热模拟实验机,在变形温度(1 173~1 373 K)和应变速率(0.01~10 s^(-1))下对52CrMoV4弹簧钢进行等温热压缩实验。基于实验所得真应力-真应变曲线,分析了热变形参数与流变应力之间的关系,建立了修正的Johnson-Cook本构模型和基于应变补偿的Arrhenius本构模型,并对两种本构模型的准确性和有效性进行了比较。结果表明,52CrMOV4弹簧钢的流变应力随着温度的升高和应变速率的降低而降低。通过精度分析可知,修正Johnson-Cook模型的相关系数为0.989 55,平均绝对相对误差为5.4625%,均方根误差为6.870 29 MPa,计算较为简单却具有较高的准确性。而应变补偿的Arrhenius模型的相关系数为0.990 23,平均绝对相对误差为4.4319%,均方根误差为6.226 64 MPa,其精度较修正Johnson-Cook模型更高,可以更 好地预测52CrMoV4弹簧钢的流变应力行为并作为热变形工艺及有限元模拟参数选择的依据。

Based on the research on hot forging and hot compression deformation process of 52CrMoV4 spring steel for trailing arm, isothermal thermocompression experiments were performed by adopting Gleeble-3500 thermal simulation testing machine to test 52CrMoV4 spring steel at deformation temperature(1 173—1 373 K)and strain rate(0.01—10 s^(-1)).Based on the true stress-true strain curves obtained from the experiment, the relationship between thermal deformation parameters and flow stress were analyzed, a modified Johnson-Cook constitutive model and an Arrhenius constitutive model based on strain compensation were established.The accuracy and effectiveness of the models were compared.The results show that the flow stress of 52CrMoV4 spring steel decreases with the increase of temperature and the decrease of strain rate.The accuracy analysis shows that the correlation coefficient of the modified Johnson-Cook model is 0.989 55,the average absolute relative error is 5.4625%,and the root mean square error is 6.870 29 MPa, although the calculation is relatively simple, it shows high accuracy.The correlation coefficient of the strain-compensated Arrhenius model is 0.990 23,the average absolute relative error is 4.4319%,and the root mean square error is 6.226 64 MPa.Its accuracy is higher than that of the modified Johnson-Cook model, and it can better predict the rheology of 52CrMoV4 spring steel.The stress behavior is used as the basis for the selection of thermal deformation process and numerical simulation parameters.