Characterization of Plastic Deformation in Lath Martensitic Steel by Micro-pillar Compression Focused on Sub-block and Lath Boundaries

Abstract

Ti/Ta-reduced activation ferritic/martensitic (RAFM) steel used in this study composes one class of lath martensite that has a hierarchically-arranged crystallographic structure. Due to the multi-scale complexity in the microstructure, mechanical characterization at the appropriate level is required to understand the role of each hierarchical feature. In this study, uniaxial micro-pillar compression tests combined with rigorous crystal orientation analysis were performed to figure out the specific influences of the lath and sub-block boundaries on the plasticity in the lath martensite-structured Ti/Ta-RAFM steel. By conducting a postmortem slip trace analysis and comparing the critical resolved shear stress of each activated slip system, we confirmed that there is no strengthening effect from either the lath or sub-block boundaries.