An accurate method for crystallographic reconstruction of parent austenite from inherited martensite in a low-alloy steel

Abstract

The microstructure of austenite at high temperatures, which cannot be reserved at room temperatures, determines the properties of its transformed phase in low-alloy steels. Consequently, an accurate method is herein developed to reconstruct local orientations of the parent austenite (γ) phase from electron backscatter diffraction maps of the martensite (α′ ) microstructure. The orientation map of α′ is cropped into a grid of data squares as the reconstruction unit. The cropped square is then divided into the square inherited from only one γ grain and the square inherited from more than one γ grain. The local orientations around parent γ grain boundaries are more accurately determined using a newly proposed reconstruction criterion. Furthermore, the solution spaces for the orientation relationship and the parent γ orientation are refined, which simultaneously improves the calculation accuracy and efficiency of reconstruction procedure. The validated reconstruction method is applied to obtain local orientations of the deformed γ microstructure accurately.