It is a stainless steel with about half of austenite and half of ferrite organization. In the case of low C content, the Cr content is in the range of 18% to 28%, and the Ni content is in the range of 3% to 10%. Some steels also contain Mo, Cu, Si, Nb, Ti, N and other alloying elements. This type of steel has both austenitic and ferritic stainless steel characteristics, compared with ferritic, plasticity, higher toughness, no room temperature embrittlement, intergranular corrosion resistance and welding performance are significantly improved, while also maintaining a ferritic stainless steel 475 ℃ brittleness and high thermal conductivity, with super plasticity and other characteristics. Compared with austenitic stainless steel, high strength and resistance to intergranular corrosion and chloride stress corrosion has been significantly improved. Duplex stainless steel has excellent resistance to pore corrosion and is also a nickel saving stainless steel.

The mechanical properties of stainless steel can be adjusted through heat treatment, in general, is a class of hardenable stainless steel. Typical grades are Cr13 type, such as 2Cr13 ,3Cr13 ,4Cr13 and so on. The hardness is higher after quenching, and different tempering temperatures have different strength and toughness combinations, mainly used for steam turbine blades, tableware, surgical instruments. According to the differences in chemical composition, martensitic stainless steel can be divided into two categories: martensitic chromium steel and martensitic chromium-nickel steel. According to the differences in organization and strengthening mechanism, it can also be divided into martensitic stainless steel, martensitic and semi-austenitic (or semi-martensitic) precipitation hardening stainless steel and martensitic ageing stainless steel

SUS301:
1/4H：250-300(HV) 1/2H：310-360 (HV) 3/4H：370-420(HV) H：430-480(HV)
EH：490-540(HV)， SH: 550(HV) or more

SUS304/ SUS316：
1/2H：250-310(HV) 3/4H：310- 370(HV) H：370- 420(HV)

SUS410 /SUS430：
1/2H：220- 260(HV) H：260- 300(HV)