An introduction to cast irons

Abstract

This chapter discusses the nature of cast irons. Cast iron or iron is a Fe–C–Si alloy that always contains minor, less than 0.1% and often alloying elements and is used in the as-cast condition or after heat treatment. Inoculation is one of the most important and widely practiced processes in cast iron production. It is used to avoid chill formation in thin sections, helps to counteract the effect of variations in raw materials and melting practice and is the final process in the ladle treatment of spheroidal irons. The properties of cast irons depend on the form of C precipitation and the matrix structure. Carbides contribute hardness and abrasion resistance. Graphite contributes machinability; wear resistance, damping, and thermal conductivity depending on its shape. The mechanical properties of cast iron are derived mainly from the matrix. These irons form the largest group of casting alloys and can be classified according to the graphite morphology into flake, malleable, spheroidal, and compacted/vermicular types. Specifications exist for all types except the relatively new, compacted/ vermicular irons.