Stainless steel is resistant to air, steam, water and other weak corrosion medium or stainless steel, also known as immortal acid steel.Stainless steel is in the iron - carbon alloy to increase the element of chromium, iron - carbon - chromium three elements combined with the metal, the carbon stability at 0.2% content, chromium content increased to 12.5%, showing rust.Stainless steel industry analysis, according to the composition can be divided into Cr series (400 series), cr-ni series (300 series), cr-mn-ni (200 series), heat-resistant chromium alloy steel (500 series) and precipitation hardening series (600 series).