Dynamic and quasi-static mechanical behaviors and microstructural mechanisms of the TWIP steel were investigated at strain rates from 0.001 to 3000 s^-1 by using a split Hopkinson tensile bar paired with interrupted strain fixtures and electron backscattered diffraction technology. The positive strain rate sensitivity of dynamic yield stress is significantly different from that of quasi-static stress at a transition strain rate of about 100 s^-1 for the different yield mechanisms. Owing to the high stress from dynamic loading, the smaller twin onset strain and the higher twin fraction as well as the more intense twin boundary-dislocation interaction are responsible for the enhanced strain hardening behavior in the early stage of strain. Nevertheless, the rapid decrease of the strain hardening rate in the later stage and the resulting negative strain hardening rate sensitivity are due to the decreasing growth rate of the twin boundary fraction. It is closely associated with the softening effect of adiabatic temperature rise (∼117 °C) by raising the stacking fault energy and inhibiting twinning activity. In addition, the fuzzy regions caused by high-density dislocations within interfaces between twin and grain boundaries may lead to the lower elongation of the dynamic tensile specimen. The grains with a high Schmid factor are conducive to slip rather than twinning, which enables the twin region orientation for slip-mediated plastic deformation. This study thus advances the understanding of the strain and strain rate dependence of the mechanical behaviors and twinning mechanisms of TWIP steels for the safety performance of automobiles.

TWIP 钢的动态和准静态力学行为和微观结构机制在 0.001 到 3000 s ^-1的应变速率下通过使用分离式 Hopkinson 拉杆与间断应变夹具和电子背散射衍射技术进行了研究。^{在约100 s -1}的过渡应变率下，动态屈服应力的正应变率敏感性与准静态应力的敏感性显着不同对于不同的收益机制。由于动态加载产生的高应力，较小的孪晶起始应变和较高的孪晶分数以及更强烈的孪晶边界-位错相互作用是应变早期应变硬化行为增强的原因。然而，后期应变硬化率的快速下降和由此产生的负应变硬化率敏感性是由于孪晶界分数的增长速度降低。它通过提高层错能和抑制孪晶活动与绝热升温（~117°C）的软化效应密切相关。此外，孪晶和晶界之间的界面内高密度位错引起的模糊区域可能导致动态拉伸试样的伸长率较低。具有高施密德因子的晶粒有利于滑动而不是孪晶，这使得孪晶区域取向用于滑动介导的塑性变形。因此，这项研究促进了对 TWIP 钢的机械行为和孪晶机制对汽车安全性能的应变和应变率依赖性的理解。