Stainless steel is an alloy consisting of iron (Fe) as the main component, mixed with chromium (Cr), nickel (Ni), etc. In General, steel containing 11% or more chromium is called stainless steel. Stainless steel is an abbreviation of "stainless steel", which means "rust-resistant steel". Because of its excellent corrosion resistance, stainless steel is widely used in space development, aircraft, automobiles, medical care, and household products. Stainless steel is roughly classified into two types, chromium-based stainless steel and chromium-nickel-based stainless steel. Also, it is further divided into five types according to its characteristics such as corrosion resistance, heat resistance, workability, non-magnetic and magnetic properties so that they can be selected based on the application.