ABSTRACT
Steel is a metal composed of iron plus varying amounts of carbon and other elements such as silicon, manganese, chromium, nickel, etc. Carbon, the most common alloying element, is the basis for primary classification. The carbon content is less than 0.10% in low-carbon steel, between 0.1 and 0.3% in medium carbon steel, between 0.30 and 2% in high carbon steel, and between 2.5 and 6% in cast iron. These classifications follow the iron-carbon phase equilibrium discussed later.
