Effect of grain size and specimen thickness on formation of mechanical twin

Abstract

Effect of grain size and specimen thickness on mechanical twinning: Origin of mechanical twins was analyzed in terms of sample thickness and grain size. Mechanical twins are developed in 316SS specimens for all thicknesses (30 µm, 50 µm and 90 µm) and for grain sizes ranging from ≈2.4 µm to ≈30 µm. Rate of twin decay increases with increase in specimen thickness and can be attributed to misorientation developments. Mechanical twin formation mechanisms in austenitic stainless steel samples were understood by electron backscattered diffraction (EBSD) based acquisition and analysis of Kikuchi diffraction patterns. Subsurface twins were found to result in a contrast in IQ maps while still not being “visible” in IPF maps. After deformation, twins grow to the surface and are subsequently identified in both IQ and IPF maps.