Abstract In this contribution, for the first time, the effect of crystal orientation on the critical stress for martensitic transformation in a medium Mn steel is explicitly revealed by using micropillar compression experiments. Although the martensitic transformation is observed in both [100] and [110] micropillars during compression tests, the average critical stress for martensitic transformation in [100] micropillars (∼483 MPa) is much smaller than that in [110] micropillars (∼700 MPa). The deformation twins can be found in the deformed [100] micropillars while the deformed [110] micropillars are free of deformation twins. The estimated critical stress for twin divergence in the [100] micropillars (∼465 MPa) is close to the corresponding critical stress for martensitic transformation. The theoretical critical stress for martensitic transformation in both [100] and [110] micropillars is estimated to be the same (650–750 MPa). The lower critical stress for martensitic transformations in the [100] micropillars could be ascribed to the formation of deformation twins, which is confirmed by the microstructural observation that the martensite nucleates at the intersections of deformation twin bundles. Two martensitic transformation pathways, namely twin-assisted martensitic transformation and free-standing martensitic transformation are proposed to explain the orientation dependent martensitic transformation observed in the present medium Mn steel.

中文翻译：

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通过微柱压缩揭示中锰钢中取向相关的马氏体转变

摘要 在这项贡献中，首次通过微柱压缩实验明确揭示了晶体取向对中锰钢马氏体转变临界应力的影响。尽管在压缩试验期间在 [100] 和 [110] 微柱中均观察到马氏体转变，但 [100] 微柱中马氏体转变的平均临界应力 (~483 MPa) 远小于 [110] 微柱中的 (~700兆帕）。变形孪晶可以在变形的[100]微柱中找到，而变形的[110]微柱没有变形孪晶。[100] 微柱中孪生发散的估计临界应力 (~465 MPa) 接近相应的马氏体转变临界应力。估计 [100] 和 [110] 微柱中马氏体转变的理论临界应力相同（650-750 MPa）。[100]微柱中马氏体转变的较低临界应力可归因于变形孪晶的形成，这通过马氏体在变形孪晶束交叉处成核的微观结构观察得到证实。提出了两种马氏体相变途径，即双辅助马氏体相变和独立马氏体相变来解释在目前中锰钢中观察到的取向相关马氏体相变。[100]微柱中马氏体转变的较低临界应力可归因于变形孪晶的形成，这通过马氏体在变形孪晶束交叉处成核的微观结构观察得到证实。提出了两种马氏体相变途径，即双辅助马氏体相变和独立马氏体相变来解释在目前中锰钢中观察到的取向相关马氏体相变。[100]微柱中马氏体转变的较低临界应力可归因于变形孪晶的形成，这通过马氏体在变形孪晶束交叉处成核的微观结构观察得到证实。提出了两种马氏体相变途径，即双辅助马氏体相变和独立马氏体相变来解释在目前中锰钢中观察到的取向相关马氏体相变。