Boundary Mechanics in Lath Martensite, Studied by Uni-Axial Micro-Tensile Tests

Lath martensite is the key constituent in advance steels that provides the overall strength. Martensite is known as hard and brittle, but recent evidence shows significant plasticity before fracture. The exactly reason is undisclosed but should relate to the underlying lath microstructure. Therefore, we studied the influence of sub-block and block boundaries on martensite plasticity through uni-axial tensile testing of individual micro-constituents, i.e. single block specimens and specimens with a single through-thickness block boundary parallel, perpendicular and at 45° to loading.