Alloy steels have been made since the advent of furnaces capable of melting iron, into which other metals may be thrown and mixed.
Though not an alloy, there exists also galvanized steel, which is steel that has gone through the chemical process of being hot-dipped in zinc for protection against rust.
Carbon Steel: Carbon steel is a metal, a combination of two elements, iron and carbon, where other elements are present in quantities too small to affect the properties. With a low carbon content it has the same properties as iron, soft but easily formed. As carbon content rises the metal becomes harder and stronger but less ductile. Typical compositions of carbon are:
Steel with sufficient carbon compositions can be heat-treated, allowing parts to be fabricated in an easily-formable soft state then made harder for structural applications. Steels are often wrought by cold-working methods, which is the shaping of metal through deformation at a low equilibrium or metastable temperature.