钢材在不同应变率下力学性能的试验研究

Experimental Study on Dynamic Mechanical Property of Q235 Steel at Different Strain Rates

摘要:

通过INSTRON拉伸试验机和HTM5020型高速拉伸试验机开展Q235钢材的准静态和高速拉伸试验，研究钢材的动态力学性能.结果表明：Q235钢材为应变率敏感型材料，随着应变率的提高，钢材的屈服强度和极限强度明显提高，钢材的应变硬化特征发生显著变化，其名义屈服强度和名义抗拉强度的动力放大系数与应变率之间满足CowperSymonds模型.基于钢材颈缩前的真实应力应变关系，提出了修正的JohnsonCook模型，该模型可更合理地描述Q235钢应变率效应与应变硬化效应耦合现象.

Abstract:

Quasistatic and dynamic tensile tests of Q235 steel were performed to study the dynamic tensile behaviors under different strain rates by INSTRON and HTM5020 testing machines. Experimental results show that Q235 steel is very sensitive to strain rates. Both the yield strength and the ultimate tensile strength of Q235 steel increase with the growth of strain rate. The hardening characteristics also vary evidently with the increasing strain rate. The dynamic increasing factors of both engineering yield stress and engineering ultimate stress can be expressed as the function of strain rates by using the CowperSymonds model. Based on the true stressstrain relationship before necking of Q235 steel, the JohnsonCook model is modified to take into account the coupled effect of strain hardening and strain rate.