Mechanical responses of nanostructured twinning induced plasticity (TWIP) steels have attracted attention owing to their ultra high strength and ductility. A set of molecular dynamics simulations were carried out to characterize and track the atomic structure of Fe–22Mn (wt. %) nanocrystalline TWIP steel during reverse loading (tension-compression). The results show that intrinsic stacking faults and deformation twins which were formed during forward tensile loading up to total strain of 5.7% were eliminated upon subsequent reverse compression loading up to strain of 0.0 %. The current study provides the first simulation evidence of detwinning in nanocrystalline TWIP steel during the reverse loading. The atomic structure and dislocation analysis show that the observed detwinning is due to the dependence of shear stress acting on the trailing and leading partial dislocations on the loading direction. The results show that the Schmid factor of the trailing partial dislocations in compression loading are larger than leading partial dislocations one. The reversible deformation by detwinning could allow for reversible plastic deformation, storage of energy and mechanical damping in micro or nano devices.

纳米结构孪生诱导可塑性（TWIP）钢的机械响应由于其超高的强度和延展性而受到关注。进行了一系列分子动力学模拟，以表征和跟踪反向加载（拉伸压缩）过程中Fe-22Mn（wt％）纳米晶TWIP钢的原子结构。结果表明，消除了在正向拉伸加载过程中形成的固有堆垛层错和变形孪晶，直至总应变为5.7％，而在随后的反向压缩加载过程中达到了0.0％时，就消除了它们。当前的研究提供了在反向加载过程中纳米晶TWIP钢解缠的第一个模拟证据。原子结构和位错分析表明，观察到的解缠是由于剪切应力对加载方向上的尾部和前部部分位错的依赖性所致。结果表明，压缩载荷中尾部局部位错的Schmid因子大于前部部分位错的Schmid因子。通过缠绕而产生的可逆变形可以允许可逆塑性变形，能量存储和微或纳米器件中的机械阻尼。