A dislocation-based model for variant selection during the γ-to-α transformation of hot rolled austenite

A phase transformation model is described that is based entirely on the presence of dislocations in deformed austenite. Each of the 24 possible Burgers vectors associated with the glide dislocations in a given crystal leads to the presence of a particular "positive slip" transformation variant. These are illustrated for the seven main components of the fee rolling fibre and are shown to be responsible for the presence of the so-called "transformed brass" component. The "transformed copper" component, on the other hand, is demonstrated to arise entirely from the reaction of in-plane glide dislocations, The superposition of the positive slip and reaction variants is shown to lead to an overall texture that is in excellent agreement with experimental observations. Such calculations involve the "weighting" of each variant according to the intensity of the parent orientation from which it is derived as well as of the relevant slip activity. The calculations indicate that the texture of rolled austenite resembles that of rolled brass much more than that of rolled copper.