The manufacture of all aluminum wrought products begins with an ingot or a continuous strip solidified from the liquid state. During molten metal processing (MMP), aluminum undergoes a series of operations that are described in this chapter including melting and alloying, recycling, molten metal treatment, control of inclusions, ingot grain refinement, and direct chill (DC) or continuous casting.

Many of the structural characteristics of steel products are a result of changes that occur during solidification, particularly volume contractions and solute redistribution. This chapter discusses the solidification process and how it affects the quality and behaviors of steel. It explains how steel shrinks as it solidifies, causing issues such as pipe and voids, and how differences in the solubility of solid and liquid steel lead to compositional heterogeneities or segregation. It describes the dendritic nature of solidification, peritectic and eutectic reactions, microporosity, macro- and microsegregation, and hot cracking, as well as the effects of solidification and remelting on castings, ingots, and continuous cast products. It explains how to determine where defects originate in continuous casters and how to control alumina, sulfide, and nitride inclusions.

This chapter describes some of the more typical manufacturing practices, along with their benefits and limitations. The manufacturing practices covered include primary melting, electroslag remelting, rolling, hot and cold drawing, and continuous casting. The chapter discusses the advance and application of powder metallurgy. A few of the more recently introduced processes that hold considerable promise for producing tool steels or finished tools at a lower cost or with improved quality also are reviewed.