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对高锰奥氏体孪晶诱发塑性(TWIP)钢室温单向拉伸与拉压疲劳行为进行了研究.单向拉伸和疲劳实验的应变速率均为6×10-3s-1.疲劳实验采取轴向总应变控制,应变比为-1.结果表明,随拉伸应变的增加,应力-应变曲线上的锯齿状塑性流动呈现出不同的特征,具有很强的应变敏感性.在不同应变幅下的低周疲劳实验中,高锰奥氏体TWIP钢表现出很强的循环硬化能力.低应变幅时表现为初始循环硬化,随后稳定;中等应变幅时,表现为初始循环硬化后出现不同程度的循环软化,然后稳定;高应变幅时经短暂循环硬化后开始循环软化,直至失效.较高应变幅下循环失效后的奥氏体晶粒内产生了大量的位错、位错墙、迷宫结构以及位错胞等位错结构,在部分晶粒内还观察到了细小的形变孪晶.
The uniaxial tensile and tension-compression fatigue behaviors of TWIP steel subjected to high-manganese austenite at room temperature were studied.The strain rates in uniaxial tensile test and fatigue test were both 6 × 10-3s-1. Taking the total axial strain control, the strain ratio is -1.The results show that the jagged plastic flow on the stress-strain curve shows different characteristics with the increase of tensile strain, and has a strong strain sensitivity.In different strain In low amplitude fatigue test, the high manganese austenitic TWIP steel showed a strong ability of cyclic hardening, which showed initial cyclic hardening at low strain amplitude and then stabilized. At medium strain amplitude, it appeared as the initial cyclic hardening Soften and then stabilize with different degrees of recycle; At high strain amplitude, it can be softened and circulated and softened by short cycle hardening until failure. Large amount of dislocations and dislocation walls occur in the austenite grains after cyclic failure at high strain amplitude , Labyrinth structure and dislocation cell dislocation structure, in the part of the grain also observed small deformation twins.