形变温度对Fe-20Mn-3Cu-1.3C TWIP钢拉伸变形行为的影响

Effect of Deformation Temperature on Tensile Deformation Behavior of Fe-20Mn-3Cu-1.3C TWIP Steel

运用温控拉伸实验,分析了在-100~200℃范围内变形时形变温度对Fe-20Mn-3Cu-1.3C钢力学性能和形变机理的影响。观察分析了拉伸试样的显微组织,并利用热力学经典模型,估算了温度对孪晶诱发塑性(TWIP)钢层错能的影响。结果表明:随着形变温度的升高,TWIP钢的层错能显著增加,基体中形变孪晶的体积分数逐渐减少,抗拉强度和屈服强度呈下降趋势,而伸长率先升高后降低,塑性变形机制也由孪生为主逐渐转变为以滑移为主。层错能的拟合公式为γSFE=26.73+9.38×10^(-2) T+4.22×10^(-4 )T2-4.47×10^(-7) T^3,与滑移相比,孪生可获得更高的应变硬化率,从而使TWIP钢获得高强度和高塑性。

The effect of deformation temperature on the mechanical properties and deformation mechanism of Fe-20Mn-3Cu-1.3Ctwinning induced plasticity（TWIP）steel when deformed at-100-200℃was analysed by temperature controlled tensile tests.The microstructure of tensile samples was observed and analysed,and then the effect between stacking fault energy of TWIP steels and deformation temperature was calculated by thermodynamic model.The results show that with the deformation temperature increasing from-100℃to 200℃,the stacking fault energy of this steel gradually increases,but the volume fraction of twins gradually decreases.The tensile strength and yield strength will gradually decline,while the elongation of this steel firstly increases,then decreases.Furthermore,in this process,the plastic strain mechanism is transformed from twinning to slipping.The stacking fault energyγSFEis calculated by the equationγSFE=26.73＋9.38×10^-2 T＋4.22×10^-4 T-2-4.47×10^-7T-3.As compared with slipping,the twinning can obtain higher strain hardening rate,which leads to high strength and plasticity of the TWIP steel.