ABSTRACT
The unifying consideration for these alloy classes is the absence of precipitation hardening; nevertheless, there may be a variety of thermal treatments in their processing. Furthermore, strengthening by strain hardening has greater importance than for those able to be precipitation hardened, and so the processing sequence frequently ‰nishes with mechanical shaping. The principal dispersoid alloying is with transition elements (Mn, Fe, Cr, Ni), but there are others forming stable intermetallics (Zr and rare earths). The primary solute element is Mg because it has a stronger effect than others and causes little change in density. These alloys fall into the 3000, 4000, and 5000 series that are described with their applications in Section 1.5. The precipitation hardening alloys are covered in Chapter 6, since the hot workability of a given composition varies greatly with the solute level and precipitate size and distribution.
