To study the dynamic mechanical properties of 40Cr steel during cold rolling forming, the compression experiments for 40Cr were carried out with split Hopkinson pressure bar apparatus, and the stress-strain curves of 40Cr were measured at different strain rates ( 600 ~ 5 000 s1 ) and temperatures ( 20 ~ 400 ℃ ). The experiment results show that 40Cr has some sensitivity to strain rate and strain rate strengthening effects. The adiabatic heating during plastic deformation at high strain rate leads to thermal weakening. Based on the dislocation dynamic theory, the dynamic constitutive model of 40Cr was obtained by the experimental results. The model results were compared with experiment. The results show that the present dynamic constitutive model can make a prediction to the plastic flow stress at different strain rates and temperatures.%为了研究高速冷滚打过程中工件材料40Cr钢的动态力学特性,利用分离式Hopkinson压杆试验装置对40Cr钢进行了压缩试验,获得40Cr钢在不同应变率(600 ～5000s-1)和不同温度(20～400℃)条件下的应力-应变情况.试验结果表明:40Cr钢对应变率呈现出一定的敏感性和应变率强化效应,塑性变形过程中产生的绝热升温对材料具有热软化作用.基于位错动力学理论,通过试验数据,建立了40Cr钢的动态本构模型.模型计算结果和试验结果对比表明:该模型可以较好地预测40Cr钢在不同应变率和温度条件下的塑性流动应力.
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