Slight to moderate deformations
Hot forming metallurgy

Figure 5 shows variations in the macroscopic yield strength σ_e of an annealed metal with temperature and strain rate. Essentially, two temperature ranges can be distinguished. At low temperatures, σ_e decreases very slowly with increasing temperature and does not depend on the strain rate: this range is called the athermal plateau and corresponds to the cold deformation (T/T_f < 0.3) described elsewhere in this treatise [29]. At higher temperatures, the decrease in σ_e with increasing temperature becomes much more rapid: this is a thermally activated domain corresponding to hot deformation (T/T_f...