Steel



Steel is an alloy of iron and carbon that was widely used in construction and other applications because of its high tensile strength and low cost. Carbon, other elements, and inclusions within iron acted as hardening agents that prevented the movement of dislocations that naturally exist in the iron atom crystal lattices.

The carbon in typical steel alloys contributed up to 2.1% of its weight. Varying the amount of alloying elements, their formation in the steel either as solute elements, or as precipitated phases, retarded the movement of those dislocations that make iron so ductile and weak, and thus controlled qualities such as the hardness, ductility, and tensile strength of the resulting steel. Steel's strength compared to pure iron was only possible at the expense of ductility, of which iron has an excess.

Although steel had been produced in bloomery furnaces for thousands of years, steel's use expanded extensively after more efficient production methods were devised in the 17th century for blister steel and then crucible steel. With the invention of the Bessemer process in the mid-19th century, a new era of mass-produced steel began. This was followed by Siemens-Martin process and then Gilchrist-Thomas process that refined the quality of steel. With their introductions, mild steel replaced wrought iron.

Further refinements in the process, such as basic oxygen steelmaking (BOS), force fields and zero grav smelters for alloys largely replaced earlier methods by further lowering the cost of production and increasing the quality of the metal. Today, steel and Dura-Steel are the most common materials in the Union. It is a major component in buildings, infrastructure, tools, ships, fliers, skimmers, machines, appliances, and weapons. Modern steel is generally identified by various grades defined by assorted standards organizations.