Fe-11Mn-4Al-0.2C中锰钢准静态和动态变形行为

Quasi-Static and Dynamic Deformation Behavior of Fe-11Mn-4Al-0.2C Medium-Mn Steel

本文对比了Fe−11Mn−4Al−0.2C中锰钢变形过程中增塑机制和力学性能的演变规律.随应变速率增加(0.002~200 s^(-1)),中锰钢屈服强度和抗拉强度的变化趋势截然相反,屈服强度从507 MPa增加到649 MPa,但抗拉强度却从1089 MPa降低到876 MPa.准静态加载时增塑机制以强相变诱导塑性(transformation-induced plasticity,TRIP)效应为主;动态加载初期增塑机制以弱TRIP效应为主,加载后期TRIP效应消失,转变为温升软化效应和孪晶诱导塑性(twinning-induced plasticity,TWIP)效应.动态加载初期的位错运动速率远高于准静态的,这导致动态的屈服强度高于准静态的.随着应变的增加,动态加载逐渐累积的绝热温升抑制了马氏体相变,降低了加工硬化能力,而准静态加载则不断产生高硬度马氏体,导致准静态的抗拉强度高于动态的.

The evolution of plasticizing mechanism and mechanical properties of the Fe-11Mn-4Al-0.2C medium-Mn steel during deformation were compared in this paper.With the increase of strain rate(0.002~200 s-1),the trends of changes in yield strength and tensile strength for the medium-Mn steel are completely opposite.The yield strength increases from 507 MPa to 649 MPa,while the tensile strength decreases from 1089 MPa to 876 MPa.The plasticizing mechanism of quasi‑static loading is dominated by the strong TRIP(transformation‑induced plasticity)effect.The plasticizing mechanism is dominated by the weak TRIP effect in the initial stage of dynamic loading,and the TRIP effect disappears and the plasticizing mechanism changes into the temperature rise softening effect and the TWIP(twinning‑induced plasticity)effect in the later stage of dynamic loading.The dislocation motion rate in the initial stage of dynamic loading is much higher than that of quasi‑static loading,which results in the higher yield strength of dynamic loading than that of quasi‑static loading.With the increase of strain,the cumulative adiabatic temperature rise inhibits the martensitic transformation and reduces the work‑hardening capacity under dynamic loading,while the high hardness martensite is produced continuously under quasi‑static loading,which results in the tensile strength of quasi‑static loading higher than that of dynamic loading.