Stainless steel is low-carbon, iron-alloy strands. It increases its corrosion resistance properties and hardens and toughens the steel, especially at high temperatures. Steel is considered stainless if it contains a minimum of 10.5% Chromium (Cr) by mass. It is thus an alloy of iron (FE) and chromium (Cr), with a controlled amount of carbon © content. Chromium combines with oxygen to form a protective layer of chromium oxide that helps resist rust.