Martensitic, or hardenable stainless steels, are classified in the 400 series. This series is known for: higher levels of carbon than ferritics. ability to be heat treated to a wide range of hardness and strength levels.

Ferritic stainless steel forms one of the five stainless steel families, For example, many of AISI 400-series of stainless steels are ferritic steels. By comparison with austenitic types, these are less hardenable by cold working, less weldable, and should not be used at cryogenic temperatures. Some types, like the 430, have excellent corrosion resistance and are very heat tolerant.