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对HC340LA低合金高强钢板分别施加5%、10%、15%的拉伸预应变,通过准静态和冲击拉伸实验,获得不同应变率下、不同预应变量试样的应力-应变曲线。实验结果表明,HC340LA高强钢对预应变和应变速率敏感,流动应力随着预应变量和应变率的提高而增大。在超过600s-1的高应变速率下,绝热温升效应使材料发生软化,不同预应变量下的材料随应变率的提高延塑性增大。分别基于流动应力模型和Johnson-Cook本构模型拟合实验数据,确立了各种状态下的本构关系。该研究可为考虑成形历史的汽车零部件的碰撞仿真提供可靠的原始数据。
The prestrain of 5%, 10% and 15% was applied to HC340LA low alloy high strength steel. The quasi-static and impact tensile tests were carried out to obtain the stress-strain curves of different prestrain specimens. The experimental results show that HC340LA high-strength steel is sensitive to pre-strain and strain rate, and the flow stress increases with the increase of pre-strain and strain rate. At high strain rates over 600s-1, adiabatic temperature rise causes the material to soften, and the material ductility increases with increasing strain rate at different pre-strain rates. Based on the experimental data of flow stress model and Johnson-Cook constitutive model respectively, the constitutive relations of various states were established. This study provides reliable raw data for crash simulation of automotive parts taking into account the forming history.