Fine-grained alloys by thermomechanical processing

Grain refinement during thermomechanical processing is conventionally achieved by discontinuous recrystallization. However, techniques involving severe deformation which increase the grain boundary area and can result in a micron-scale grain size by a process of continuous recrystallization have been developed. Various methods which are based on control of the deformation conditions and cooling rate during hot rolling of steels have utilised the α–γ phase transformation to produce micron-grained ferrite. Ultra-fine-grain structures exhibit interesting mechanical properties, and in certain cases a large amount of strengthening may be achieved with little or no reduction in ductility.