Stainless steels are iron based alloys containing at least 10.5% Chromium. They achieve their stainless characteristics through the formation of an invisible and adherent Chromium rich oxide film. Alloy 304 is a general purpose austenitic stainless steel with a face centered cubic structure. It is essentially non-magnetic in the annealed condition and can only be hardened by cold working. The lower Carbon content compared with alloy 302 gives better corrosion resistance in welded structures.