Steels are the most-used metallic materials. By alloying with carbon and other alloying elements, in combination with thermal and thermo-mechanical treatments, its properties can be adapted for a broad range of applications. In its untreated condition, steel is very soft and thus excellently suited to being worked into different shapes. By contrast, applying an individually-adapted temperature-time regime can achieve properties which perfectly match the desired requirements. Modern developments are aimed at manufacturing steel which is simultaneously strong and workable - as a contribution to industrial light engineering of machines.
http://en.wikipedia.org/wiki/Steel