The martensite phase transformation dependence upon deformation modes and strain paths in a medium manganese (10 wt%) TRIP steel stamped into a T-shape panel was quantified through combination of 3D digital image correlation and synchrotron X-ray diffraction. The T-shape emulates a portion of a common anti-intrusion component. The stamping speed was kept intentionally slow (1 mm/s) so as to avoid excessive heat generation. The steel, which belongs to the third generation advanced high strength steel (3GAHSS) family, was chosen for two reasons: (1) it is two-phase, i.e. austenite and ferrite, with martensite resulting from deformation-induced phase transformation; (2) the 66 vol.% initial retained austenite volume fraction (RAVF) enabled a thorough examination of the martensite phase transformation at large deformation levels without exhaustion. Strain fields were coupled with measured RAVF values of small specimens extracted from specific locations on a formed T-shape panel. This enabled an exploration of the effects of linear, bilinear, and non-linear strain paths as well as deformation modes such as tension, plane strain, biaxial tension, and equibiaxial tension. Results suggest a significant martensite phase transformation dependence on deformation mode and strain path in the absence of fracture and when martensite phase transformation is unaffected by heat generated during forming. In general, the uniaxial and biaxial tension deformation modes facilitate the martensite phase transformation, while the smallest amount of martensite phase transformation occurs under plane strain. Some discussion as to further application of the experimental methods detailed in this study to other 3GAHSS and the effects of fracture on martensite phase transformation is provided.

通过将3D数字图像相关性和同步加速器X射线衍射相结合，对冲压成T形面板的中锰（10 wt％）TRIP钢中的变形模式和应变路径所依赖的马氏体相变进行了定量。T形模仿通用的防入侵组件的一部分。刻意将冲压速度保持在较低的速度（1 mm / s），以避免产生过多的热量。选择该钢属于第三代高级高强度钢（3GAHSS）系列，其原因有两个：（1）它是两相，即奥氏体和铁素体，马氏体是由变形引起的相变产生的；（2）66卷％初始残余奥氏体体积分数（RAVF）使得能够在大变形量下彻底检查马氏体相变而不会耗尽。应变场与从形成的T形面板上的特定位置提取的小样本的RAVF值相结合。这使得能够探索线性，双线性和非线性应变路径以及变形模式（例如张力，平面应变，双轴张力和等双轴张力）的影响。结果表明，在没有断裂的情况下，以及在成形过程中产生的热量不影响马氏体相变的情况下，马氏体相变对变形模式和应变路径的依赖性很大。通常，单轴和双轴拉伸变形模式有助于马氏体相变，而马氏体相变的最小发生在平面应变下。本研究中详细介绍的实验方法在其他3GAHSS中的进一步应用以及断裂对马氏体相变的影响提供了一些讨论。