45#钢热粘塑性本构参数的确定及应用

基于45#钢3种不同热处理状态的材料测试系统(MTS)和Hopkinson不同加载条件(应变率10-3~103/s)下的真应力-真应变曲线,利用最小二乘法拟合了Johnson-Cook本构关系中的待定参数,修正了应变率硬化指数,拟合的本构关系参数的计算值与实验数据比较,吻合很好.数值模拟结果与霍普金森压杆(SPHB)实验曲线的对比说明,修正的Johnson-Cook本构关系可以更真实地描述冲击载荷条件下45#钢的力学行为.在此基础上获得了本构关系参数与材料组织铁素体体积分数之间的定量关系,为高应变率载荷条件下使用的45#钢热处理工艺制定提供了科学依据.

Determination of the Thermo-Viscoplastic Constitutive Relations of 45# Steel

Based on the true stress-true strain curves of 45# steel under three kinds of heat-treated conditions obtained at strain rates from 10-3s-1~103s-1 by means of material test system(MTS) and split Hopkinson pressure bar(SHPB),the undetermined coefficients of the Johnson-Cook constitutive relations were fitted with least squares theory,and the strain rate hardenability value was corrected.It is proved that the constitutive relation parameters are in agreement with the experimental results.The contrast between numerical simulation and experimental data obtained by SHPB demonstrate that the corrected Johnson-Cook constitutive relation can describe the mechanical behavior of 45# steel under impact loading.According to the analysis referred to above,the quantitative relation between the constitutive relation parameters and the content of ferrite is determined,which provides rules for selecting the heat treatment processes of 45# steel at high loading rate.