Usually stainless steel can be divided into following categories by matrix structures:

1. Ferritic stainless steel, which contains 12% ~ 30% Cr. Its corrosion resistance, toughness and weldability is improved with the increase of Cr content, and its resistance against chloride stress corrosion is superior to other types of stainless steel.

2. Austenitic stainless steel, which contain over 18% Cr, about 8% Ni and a small amount of Mo, Ti, N and etc. It has good overall performance and is resistant to a variety of chemical medium corrosion.

3. Austenitic-ferritic duplex stainless steel, which has the merits of both austenitic and ferritic stainless steel. It has an excellent performance in superplasticity as well.

4. Martensitic stainless steel, which is of high strength but bad in plasticity and weldability.

According to chemical composition, it can be divided into CR series (SUS400), CR-NI series (SUS300), CR-MN-NI(SUS200) and precipitation hardening series (SUS600).

200 series - Cr - Ni - Mn austenitic stainless steel

300 series - Cr - Ni austenitic stainless steel

400 series - ferritic and martensitic stainless steel

500 series - heat resistant chromium alloy steel

600 series - martensitic precipitation hardening stainless steel