ABSTRACT
The billet (ingot) during casting can be subdivided into several stages with distinctly different characteristics. We mentioned in Chapter 1 (Figure 1.6) the sump and the transition region. Other terms can be found in the literature, e.g., liquid pool, slurry zone, and mushy zone. There is also the solid part of the billet (ingot). We have to defi ne these terms because there are discrepancies in the literature about what is actually what. Figure 3.1a shows a schematic cross-section of a billet with isotherms of liquidus, coherency,* [1] and solidus, and the defi nition of the different zones of the billet. The real sump profi le is shown in Figure 3.1b.
