Decoupling the orientation dependence of deformation-induced martensitic transformation via single-crystal micropillar compression

Abstract

This study explores the significant orientation dependence of deformation-induced martensitic transformation. By employing single crystalline micropillar compression, three typical low-index crystallographic orientations were selected to examine their influence on the martensitic transformation of metastable austenitic stainless steel. Results demonstrate that the [011] orientation significantly inhibits the formation of α'-martensite, whereas the [001] and [111] orientations more effectively facilitate phase transformation, which is closely related to the transformation mechanisms. Specifically, the [001] orientation, which is prone to stacking fault formation, promotes martensitic transformation significantly with the aid of ε-martensite and the decreased effective stacking fault energy during compression. Meanwhile, the [111] oriented pillars demonstrate the highest yield strength, with shear deformation responsible for the relatively high fraction of α'-martensite. Additionally, the non-Schmid behavior occurred in the [011]- and [111]- oriented micropillars were found and discussed. This research advances the understanding of orientation-dependent martensitic transformation and provides an optional way to tailor the Transformation-induced plasticity effect via grain orientation engineering.