Identification of dynamic ferrite formed during the deformation of super-cooled austenite by image-based analysis of an EBSD map

Abstract

Differentiation of dynamically and statically transformed ferrites in SIDT (Strain-Induced Dynamic Transformation) steel was carried out by various image-based analyses of EBSD (Electron BackScattered Diffraction) maps. Various identification methods were tried on the basis on the grain size, and the intra- and inter-granular misorientations. The grain-size-based method was valid only when a bimodal grain size distribution in the ferrite phase, due to the large prior austenite grain size, appeared in the specimen. On the other hand, using the proposed method based on both intra- and inter-granular misorientations, the dynamically transformed ferrite could be effectively extracted from SIDTed steel, even in steel in which the grain sizes of the dynamically and statically transformed ferrites were alike.