Third-generation advanced high-strength steels possess an exceptional combination of high strength and ductility owing to their high work-hardening rate during deformation. In this study, the mechanical properties and microstructure/texture evolution of medium-Mn steel under various loading conditions (uniaxial tension, in-plane torsion, and equibiaxial tension) were investigated. Interrupted electron back-scattered diffraction and X-ray diffraction characterizations were carried out to track the microstructure and texture evolution of individual phases. Digital image correlation was employed for the in-situ measurement of formation and expansion of deformation bands, i.e., the Lüders and the Portevin-Le Châtelier (PLC) bands. The dynamic strain aging effect in terms of the formation of PLC bands and stress serrations was significantly affected by the loading conditions and stress level. Multiple types of stress serrations were observed in all tested specimens at different deformation stages. The texture evolution of the steel under various deformation modes was further tracked. Ferrite and fresh martensite exhibited the plain texture evolution like most body-centered cubic metals, whereas austenite showed a more complex texture evolution. The martensitic transformation notably decreased the RD||<001> intensity of the austenite; austenite debris was rotated with ferrite grains, while some intact austenite grains self-rotated to a stable orientation, which is unfavorable for martensitic transformation. The obvious intragranular orientation gradient observed in the austenite intact grains implies that considerable deformation occurred in the austenite. Finally, the experimental results indicate that equibiaxial tension primarily promoted the martensitic transformation, and the classical Olson–Cohen model was calibrated to capture the volume fraction evolution of austenite under various stress states.

第三代先进高强度钢由于其在变形过程中的高加工硬化率而具有高强度和延展性的特殊组合。在这项研究中，研究了中锰钢在不同载荷条件下（单轴拉伸、面内扭转和等双轴拉伸）的力学性能和显微组织/织构演变。进行断续电子背散射衍射和 X 射线衍射表征以跟踪各个相的微观结构和织构演变。采用数字图像相关法对变形带的形成和扩展进行原位测量，即、Lüders 和 Portevin-Le Châtelier (PLC) 乐队。在形成 PLC 带和应力锯齿方面的动态应变时效效应受加载条件和应力水平的显着影响。在不同变形阶段的所有试样中均观察到多种类型的应力锯齿。进一步跟踪了钢在各种变形模式下的织构演变。铁素体和新鲜马氏体表现出与大多数体心立方金属一样的普通织构演变，而奥氏体则表现出更复杂的织构演变。马氏体相变显着降低了奥氏体的RD||<001>强度；奥氏体碎片随铁素体晶粒旋转，而一些完整的奥氏体晶粒自旋转至稳定取向，不利于马氏体相变。在奥氏体完整晶粒中观察到的明显的晶内取向梯度意味着在奥氏体中发生了相当大的变形。最后，实验结果表明等双轴张力主要促进了马氏体转变，并且经典的 Olson-Cohen 模型被校准以捕获在各种应力​​状态下奥氏体的体积分数演变。