Steel is an alloy made up of carbon and steel. The combination may vary, but steel is renowned for tensile strength. The carbon and iron form a crystal lattice reinforcing the sturdy metal.
Steel contains between 0.002 percent and 2.1 percent carbon with varying amounts categorizing the quality of the steel. Low carbon in the alloy produces a malleable alloy while high amounts of carbon result in a hard, brittle alloy commonly referred to as pig iron. Steel alloys can also be modified by adding small quantities of manganese, nickel, phosphorous, sulfur and several other elements. Small traces of oxygen, nitrogen and aluminum are also common.
If the alloy is cast with more than 2.1 percent carbon, it is considered cast iron. Similarly, steel differs from wrought iron in the large amounts of slag in the latter.
Stainless steel is a common steel used for its strength and ability to resist corrosion. Stainless steel is made by adding chromium to the steel to add an oxide protective film to the surface.
Modern-day steel production is a huge industry dwarfing the second most produced metal, aluminum. The main reasons for its success are the cheap production costs, abundance of raw materials and large range of mechanical properties.