Aerospace Stainless Steel

Generally speaking, oxidation or corrosion resistance is proportional to the amount of chromium contained in the steel. In order for the chromium additive to accomplish this, oxygen must be present. Should any breaks in the chromium oxide coating occur, the chromium oxide, in the presence of oxygen, can regenerate itself and therefore sustain this protection. Should there be an absence of oxygen, or in some reducing conditions, this protective film may be destroyed, and consequently, the stainless steel is termed active. 
Most stainless or heat resisting steels are either melted by the electric furnace process or vacuum arc re-melted. 
Heat treatment for hardness and strength is recommended mainly for straight chromium steels. Cold working is generally utilized for the chromium-nickel classes of steel and has the advantage of increasing strength while retaining good ductility.