Plastic Deformation: Role of Recovery and Recrystallization

Abstract

At temperatures above 0.5 Tm, where Tm is the melting temperature of metallic materials in degrees absolute, the strain hardening produced by plastic deformation tends to be counteracted by dynamic restoration processes, i.e., dynamic recovery (DRV) and dynamic recrystallization (DRX), leading to little or no strain hardening or even to strain softening at high strains, see Figure 1. In materials of low stacking fault energy (SFE) or under deformation conditions in which DRV is significantly retarded, the dislocation density increases to a high level and eventually the local differences in density are high enough to permit the nucleation of new grains followed by the migration of high angle boundaries (HABs). Such conventional DRX leads to the elimination of large numbers of dislocations and so brings about clearly observable strain softening in the flow curves accompanied by the evolution of a new equiaxed grain structure. This will be categorized here as discontinuous DRX (dDRX).