Reconstructing the austenite parent microstructure of martensitic steels: A case study for reduced-activation Eurofer steels

Abstract

A computer program was employed to reconstruct the parent microstructure from electron backscatter diffraction maps taken from martensite. The reconstruction is based on a given user-selected orientation relationship. Two reduced-activation ferritic-martensitic Eurofer steels were austenitized for several times and cooled down at different rates. Two parameters are proposed to assess the quality of the reconstruction: the relative frequency of orientations in a determined sub-portion of the Euler space and the distribution of the angular deviation from a given theoretical orientation relationship. The number of active martensitic orientation variants during the transformation depends on grain size. Coarser grains enable a greater number of active variants improving the reconstruction quality. The distributions of angular deviations reveal that the Greninger-Troiano orientation relationship is the one that best describes the martensitic transformation in both steel grades.