Stainless steel is the weak medium such as air, steam and water corrosion - resistant steel, and acid - proof steel refers to acid, alkali, salt and other chemical leaching corrosion of steel corrosion medium. Stainless steel has come out since the beginning of this century, and now has more than 90 years of history. The invention of stainless steel is a major achievement in the history of Metallurgy in the world, stainless steel development of the Foundation for the development of modern industry and scientific and technological progress important material and technical basis. Many of stainless steel, performance varies, it gradually formed a few categories in the development process.