Chapter 13 - Hot Deformation and Dynamic Restoration

Abstract

The purpose of this chapter is to illustrate hot deformation and dynamic restoration. The softening processes of recovery and recrystallization may occur during deformation at high temperatures. In this case the phenomena are called dynamic recovery and dynamic recrystallization in order to distinguish them from the static annealing processes which occur during post-deformation heat treatment. The static and dynamic processes have many features in common, although the simultaneous operation of deformation and softening mechanisms leads to some important differences. Dynamic recovery and dynamic recrystallization form part of the much larger subject of hot working. Dynamic recovery and dynamic recrystallization occur during metalworking operations such as hot rolling, extrusion, and forging. They are important because they lower the flow stress of the material, thus enabling it to be deformed more easily and they also have an influence on the texture and the grain size of the worked material. Dynamic recrystallization may also occur during creep deformation, the main difference between hot working and creep being the strain rate.