Steel: Iron, Carbon and Material Grades

Steel is a family of iron-based alloys in which carbon is a key constituent. It is an engineering material family, rather than a chemical element or one fixed recipe. Different steels contain different amounts of carbon and other elements. World Steel Association definition · TWI steel-family explanation

Iron, alloy and steel

Iron is an element. An alloy combines chemical elements, at least one of which is a metal. Steel is an example built around iron and carbon; carbon itself is not a metal. Calling steel an alloy therefore does not mean that all its constituents must be metals. World Steel Association alloy definition

A general description of steel cannot serve as the composition specification for every grade. Worldsteel’s introductory page gives a simplified iron–carbon description, while TWI describes additional alloying elements across the steel family. The specified grade is the more precise material identity. Worldsteel introduction · TWI family and composition

Carbon steel and stainless steel

Carbon steels and stainless steels are both steels. Chromium is a defining constituent of stainless steels: worldstainless identifies a minimum chromium content of 10.5% by mass as a common family characteristic. This is a composition distinction, not a universal guarantee about performance in every environment. These two names do not exhaust all steel classifications. worldstainless family description · TWI chromium distinction · Salzgitter steel classes

Grade, form and condition

These descriptions are connected but do different jobs. Worldsteel lists forms such as coil, plate, sections and bars. Salzgitter explains European grade names organized around intended use and properties or around chemical composition, and distinguishes delivery conditions such as as-rolled and normalized. A shape name alone does not identify the grade. Worldsteel product forms · Salzgitter names and conditions

Material identity and production route

Common steelmaking routes include blast furnace–basic oxygen furnace production and electric arc furnace production. They use different raw-material and process arrangements, but the route name alone is not a finished material grade. Worldsteel steelmaking overview

For a copper-based alloy family, see brass basics. The metal supply section connects related material definitions. This page explains material identity; it does not select a grade or assign strength, hardness or corrosion limits to unspecified steel.