Orientation relationship between austenite and bainite in a multiphased steel

A first method is proposed to evaluate the “average” orientation relationship which may exist between two neighbouring different crystallographic phases from electron back scattering diffraction orientation cartographies. This method is applied to a multiphased steel for which the crystallographic orientation relationship between austenite and bainite can be expressed as a 44.5° rotation around a <0.13, 0.13, 0.98> axis. A second method is then proposed to determine all possible transformation products of a given austenite orientation. This statistical treatment of electron back scattering diffraction data allows to detect a possible variant selection which may occur during phase transformation. It is illustrated by the determination of the transformation products of 80 Copper oriented grains of austenite and actually reveals that some expected variants are missing experimentally.