应变速率对中碳低温贝氏体钢强塑性的影响

Effect of strain rate on strength and plasticity of medium carbon low-temperature bainitic steel

为探索低温贝氏体钢的断裂行为,研究应变速率对低温贝氏体钢TRIP效应的影响,采用不同应变速率的拉伸试验对低温贝氏体钢的强塑性进行研究。利用扫描电镜(SEM)、透射电镜(TEM)及X射线衍射(XRD)等试验方法对低温贝氏体钢的微观组织、断口形貌及裂纹走向进行表征。结果表明,随着应变速率的提高,试验钢的屈服强度由771 MPa上升至806 MPa,抗拉强度由1554 MPa上升至1606 MPa,断后伸长率由13.5%下降至9.0%。主要原因是高应变速率拉伸引发的绝热温升抑制了残余奥氏体的马氏体相变,对试验钢塑性造成负面影响。

In order to explore the fracture behavior of low-temperature bainite steel and the effect of strain rate on TRIP effect process of low-temperature bainitic steel,tensile tests with different strain rates were used to study the strength and plastic properties of low-temperature bainitic steel.Scanning electron microscope(SEM),transmission electron microscope(TEM)and X-ray diffraction(XRD),etc.were used to characterize and analyze the microstructure,fracture morphology and crack propagation paths of low-temperature bainitic steel.The results show that with the increase of strain rate,the yield strength increases from 771 MPa to 806 MPa,the tensile strength increases from 1554 MPa to 1606 MPa,and the elongation after fracture decreases from 13.5%to 9.0%.The main reason is that the adiabatic temperature rise induced by high strain rate inhibits the martensitic transformation of retained austenite and has a negative effect on the plasticity of the test steel.