Texture in hot rolled austenite and resulting transformation products

By making use of a commercially processed TRIP (transformation induced plasticity) steel it was possible to directly measure the texture of hot rolled low alloyed austenite from the traces of retained austenite (9%) remaining at room temperature. This texture was used as the basis for analysing preferred orientation of the transformation products, ferrite and bainite, in the same steel. The EBSP (electron back scattering patterns) method was employed to determine textures of the different phases. The austenite condition was shown to be partially recrystallised, having a beta-fibre texture in the deformed structure and a spread from cube to Goss in the recrystallised regions The polygonal ferrite and bainite textures have many similarities but also some differences, being significantly stronger in the bainite, especially the {100}[011] component. A model is presented which explains quite well the transformation texture based on the orientation relationship between austenite and ferrite. Where appropriate, variant selectivity is incorporated by reference to accepted theories of phase transformations in steels. Both nucleation and growth are considered to play roles in defining transformation textures, depending on the physical processes which are involved. (C) 1998 Elsevier Science S.A. All rights reserved.