ABSTRACT
Comparison of the hot working behavior of Al alloys with those of other metals is of value for a better understanding of Al and enabling one to judge the feasibility of transferring forming technology from other industries (Figure 2.2) [1-11]. The relative strengths and ductilities of common metals are presented in Figure 8.1 [6] and indicate the different temperature ranges for hot forming in various industries. Such an analysis is only valid if conducted at equivalent temperatures, namely at equal fractions of the melting temperature TM (K); Figure 8.1 has been transformed to a T/TM abscissa in Figure 2.12. The §ow curves of several alloys at 0.7 TM are presented in Figure 8.2 (also Figure 2.6) [6]. The other FCC metals, Cu, Ni, and γ-Fe (Pb, Ag, Au) while sharing identical slip systems differ in undergoing diminished DRV, because the dislocations cannot so easily leave their slip planes. The difference is suf‰cient to lead to an alternative restoration mechanism, DRX [11]. The bodycentered cubic (BCC) metals, commonly α-Fe, β-Ti, β-Zr, Mo, while having different slip systems from Al do share with it a high level of DRV. The hexagonal close-packed (HCP) metals Mg, α-Ti, α-Zr with only one close-packed plane have different slip systems and ease of recovery that leads to a complex hot working behavior. The various crystal structures have been compared previously in tabular form [6] with respect to: (1) fundamental behavior related to §ow curves, ductility, mechanisms, product microstructures and (2) hot workability resulting from that behavior in FCC, BCC, HCP, and as two phases.
