Cast irons are primarily iron alloys that contain more than 2″ carbon and from 1 to 3″ silicon. This article provides a description of the iron-iron carbide-silicon system and discusses the classification, composition, and characteristics of cast irons, such as gray, ductile, malleable, compacted graphite, and white cast iron. A table shows the correspondence between the commercial and microstructural classifications as well as the final processing stage in obtaining common cast irons.

This article provides information on the classification, microstructure, castability and section sensitivity of gray iron. It describes properties of the test bar and provides a short note on fatigue limit in reversed bending. Although the ASTM size B test bar is the bar most commonly used for all gray irons from classes 20 to 60, ASTM A 48 provides a series of bar sizes, and the user can select the bar sizes that best approximates the cooling rate in the critical section of the casting.