What is stainless steel?

Stainless steel is a steel alloy of iron and chromium (minimum 10.5%). It also contains varying amounts of carbon, silicon and manganese to create different grades for different purposes. Other elements such as nickel, titanium, copper and molybdenum may be added for useful properties such as increased corrosion resistance and enhanced formability.

Chromium produces a thin layer of oxide on the surface of the steel known as the 'passive layer'. This layer is too thin to be visible, so the metal retains its lustre. Also, when the surface is scratched this layer quickly reforms. It is impervious to water and air, so protects the metal beneath, preventing any further corrosion of the surface. Increasing the amount of chromium gives stainless steel increased resistance to corrosion.