CRYSTALLOGRAPHIC TEXTURE IN MECHANICALLY ALLOYED OXIDE DISPERSION-STRENGTHENED MA956 AND MA957 STEELS

The crystallographic textures of two mechanically alloyed, oxide dispersion-strengthened steels have been studied in the as-deformed and recrystallized conditions. The MA956 steel, which has relatively large chromium and aluminum concentrations, is found to exhibit a strong [110] fiber texture in the extruded condition. Despite the larger degree of deformation imparted to MA957 during extrusion, its crystallographic texture is found to be rather weak. Significant differences have also been found in the texture after recrystallization heat treatments. These differences could not be explained on the basis of deformation or recrystallization theory. However, the discovery that under certain specific conditions MA957 partially transforms to austenite has helped rationalize the texture results. In particular, the austenite is found to form at the temperature where the extrusion process is usually carried out. The observation of austenite is found to be consistent with thermodynamic phase stability calculations and metallographic experiments.