42CrMo钢的动态力学行为及高应变率效应的本构模型

Dynamic mechanical response and a constitutive model of 42CrMo steel that incorporates the effects of high strain rates

为研究42CrMo钢的冲击动态力学性能及本构模型,进行了冲击动态压缩实验和金相观察.材料表现出强烈的应变率依赖性,同时还得到不同应变率下力学性能差异的主要原因在于冲击动态载荷下的绝热剪切行为.采用热激活理论,分别考虑热应力和非热应力来解释变形机理,得到了应变率效应的描述.基于此,本文提出含高应变率效应的动态本构模型,通过绝热剪切准则来确定失稳的起始点,并与模型进行耦合.该模型能很好地描述42CrMo钢的准静态和冲击动态力学行为,特别是应变硬化效应和应变率效应.

To study the dynamic mechanical properties and constitutive relationship of 42CrMo steel,which is primarily used in high-speed train axles,a dynamic compression test and a metallographic observation were conducted.The material exhibited strong strain-rate dependence,and the adiabatic shear behavior under dynamic loadings was found to be the dominant cause of the different mechanical properties resulting from different strain rates.The thermal activation theory,which separately considers the thermal and athermal stresses to explain the deformation mechanism,was employed to obtain the descriptions of the strain-rate effects.Accordingly,a physically based constitutive model was proposed that incorporated the effects of the high strain rates.A criterion for adiabatic shear,which was coupled to the model,was proposed to determine the onset of instability.The model was confirmed to sufficiently describe the quasi-static and dynamic mechanical behavior of the 42CrMo steel,especially the effects of strain hardening and strain rates on the yield stress.