The effects of quasi-static and low-dynamic strain rate ($\dot{\epsilon }$ = 10⁻⁴ /s to $\dot{\epsilon }$ = 10² /s) on tensile properties and deformation mechanisms were studied in a Fe-25Mn-3Al-3Si (wt%) twinning and transformation-induced plasticity [TWIP-TRIP] steel. The fully austenitic microstructure deforms primarily by dislocation glide but due to the room temperature stacking fault energy [SFE] of 21 ± 3 mJ/m² for this alloy, secondary deformation mechanisms such as mechanical twinning (TWIP) and epsilon martensite formation (TRIP) also play an important role in the deformation behavior. The mechanical twins and epsilon-martensite platelets act as planar obstacles to subsequent dislocation motion on non-coplanar glide planes and reduce the dislocation mean free path. A high-speed thermal camera was used to measure the increase in specimen temperature as a function of strain, which enabled the use of a thermodynamic model to predict the increase in SFE. The influence of strain rate and strain on microstructural parameters such as the thickness and spacing of mechanical twins and epsilon-martensite laths was quantified using dark field transmission electron microscopy, electron channeling contrast imaging, and electron backscattered diffraction. The effect of sheet thickness on mechanical properties was also investigated. Increasing the tensile specimen thickness increased the product of ultimate tensile strength and total elongation, but had no significant effect on uniform elongation or yield strength. The yield strength exhibited a significant increase with increasing strain rate, indicating that dislocation glide becomes more difficult with increasing strain rate due to thermally-activated short-range barriers. A modest increase in ultimate tensile strength and minimal decrease in uniform elongation were noted at higher strain rates, suggesting adiabatic heating, slight changes in strain-hardening rate and observed strain localizations as root causes, rather than a significant change in the underlying TWIP-TRIP mechanisms at low values of strain.

准静态和低动态应变率的影响（$\dot{\epsilon }$= 10 ^-4 / s至$\dot{\epsilon }$在Fe-25Mn-3Al-3Si（wt％）孪晶和相变诱发塑性[TWIP-TRIP]钢中，研究了拉伸强度和变形机理[ = 10 ² / s）。完全奥氏体组织主要由于位错滑移而变形，但是由于室温下的堆垛层错能[SFE]为21±3 mJ / m ²对于这种合金，二次变形机制，如机械孪晶（TWIP）和ε马氏体形成（TRIP）在变形行为中也起着重要作用。机械双胞胎和ε-马氏体血小板对随后在非共面滑行平面上的错位运动起到了平面障碍，并减少了错位的平均自由程。使用高速热像仪来测量样品温度随应变的变化，从而可以使用热力学模型来预测SFE的升高。使用暗场透射电子显微镜，电子通道对比成像和电子反向散射衍射，可以确定应变速率和应变对微观结构参数（如机械孪晶和ε-马氏体板条的厚度和间距）的影响。还研究了片材厚度对机械性能的影响。拉伸试样厚度的增加会增加极限抗拉强度和总伸长率的乘积，但对均匀伸长率或屈服强度没有显着影响。屈服强度随应变率的增加而显着增加，这表明由于热激活的短程势垒，位错滑移随应变率的增加而变得更加困难。在较高的应变速率下，极限抗拉强度有适度的增加，而均匀伸长率则有最小的下降，这表明绝热加热，应变硬化速率的细微变化以及观察到的应变局部化是根本原因，而不是根本的TWIP-TRIP发生了显着变化低应变值的机理。