Stainless steel is an alloy of iron, nickel, chrome and various other elements and impurities. During production processes these impurities form carbides and in many cases the stainless steel partly or entirely loses its corrosion proof. As a result of machining, rolling, heating and welding the original austenite structure is lost.
In these instances the stainless steel construction loses its spontaneous oxide formation properties. It is therefore essential to remove as many impurities as possible from the stainless steel once machining is complete..