Steel is an alloy of iron and carbon that may contain either elements and in which the carbon content does not exceed approximately 1.7%.

Steel is considered the ideal metal for many types of casting applications because its chemical analysis as well as its mechanical and physical properties are easily varied over a wider range than other cast metals. This is achieved by varying the carbon content, the chemical composition, or by heat treatment. It is strong, tough, dependable, and readily joined by welding or bolting to other metal forms, such as rolled products, forgings, or other castings. Steel castings are used in many industries. These include railroad, automotive, marine, farm equipment, machinery for highway, construction, mining, metalworking, power transmission, valves and fittings.