1. Classified by chemical composition.

①. CR series: ferrite series, martensite series

②. CR-NI series: austenite series, abnormal series, precipitation hardening series.

2. Classification by metallographic organization.

①. Austenitic stainless steel

②. Ferritic stainless steel

③. Martensitic stainless steel

④. Duplex stainless steel

⑤. Precipitation hardening stainless steel