There are more than a hundred different stainless steels. They all have one characteristic in common: each contains enough chromium to make the metal corrosion resistant.
There are three basic groups of stainless steel:
Stainless steel is a classification of special alloy steel that is used extensively. As the name implies, stainless steel is extremely resistant to corrosion. It costs more than carbon steel and is harder to cut and machine. However, if a machined part is expected to come into contact with a corrosive atmosphere, the extra cost is justified,
Stainless steel is commonly used to meet special sanitation requirements. It is designed for such applications as food processing and the transfer of chemicals through pipes.
All stainless steel contains high quantities of chromium alloy, and many types contain high quantities of nickel alloy. These alloys give stainless steel its superior ability to resist corrosion.