A variant selection model for predicting the transformation texture of deformed austenite

Abstract

The occurrence of variant selection during the transformation of deformed austenite is examined, together with its effect on the product texture. A new prediction method is proposed based on the morphology of the austenite grains, on slip activity, and on the residual stresses remaining in the material after rolling. The aspect ratio of pancaked grains is demonstrated to play an important role in favoring selection of the transformed copper ({311}〈011〉 and {211}〈011〉) components. The extent of shear on active slip planes during prior rolling is shown to promote the formation of the transformed brass ({332}〈113〉 and {211}〈113〉) components. Finally, the residual stresses remaining in the material after rolling play an essential part by preventing growth of the {110}〈110〉 and {100}〈uvw〉 orientations selected by the grain shape and slip activity rules. With the aid of these three variant selection criteria combined, it is possible to reproduce all the features of the transformation textures observed experimentally. The criteria also explain why the intensities of the transformed copper components are sensitive to the pancaking strain, while those of the transformed brass are a function of the cooling rate employed after hot rolling.