Duplex Stainless Steel (DSS) refers to stainless steel with ferrite and austenite each accounting for about 50%. Generally, the content of less phases needs to be at least 30%. In the case of low C content, the Cr content is 18% to 28%, and the Ni content is 3% to 10%. Some duplex stainless steels also contain alloying elements such as Mo, Cu, Nb, Ti, and N. 

The DSS has the characteristics of austenitic and ferritic stainless steel. Compared with ferrite, it has higher plasticity and ductility, no room temperature brittleness, and significantly improved intergranular corrosion resistance and welding performance, while still maintaining brittleness, high thermal conductivity, and superplasticity as ferrite stainless steel. Compared with austenitic stainless steel, DSS has high strength and significantly improved resistance to intergranular corrosion and chloride stress corrosion. Duplex stainless steel has excellent pitting corrosion resistance and is also a nickel-saving stainless steel.

Available grade of duplex stainless steel: 1.4460, 1.4462, 1.4468, 1.4469, 1.4517, 1.4770, A 890 1C, A 890 1A, A 890 3A, A 890 4A, A 890 5A, A 995 1B, A 995 4A, A 995 5A, 2205, 2507, 022Cr22Ni5Mo3N, 022Cr25Ni6Mo2N

CF8M is a cast austenitic stainless steel which covered by ASTM A351, ASTM A743 and ASTM A744 standard. CF8M equal to SS 316/F 316 and Chinese Standard 0Cr17Ni12Mo2. CF8M is a molybdenum bearing modification of CF8 alloy and is the cast equivalent of wrought AISI 316 Stainless steel. The presence of molybdenum increases the general corrosion resistance and the resistance to pitting by chlorides. The alloy is used in mildly acidic and alkaline conditions and for handling citric, oxalic and phosphoric acids. Stainless steel CF8M is mostly the same as SS 316, F 316 and TP 316. But they are defined in different standards, and their chemical and mechancial properties are a little different too. CF8M is defined in ASMT A351, ASMT A743 and ASTM A744, which is for casting purpose only. SS 316 is defined in ASTM A240 and ASTM A276, it's for plate, sheet, strip or stainless steel bars. Another grade is named as F316, which is from ASTM A182 for forged parts only. TP316 will be found in ATSTM A376 for pipe only. The main applications of CF8M cast stainless steel cover: impellors, propellers, pump casings, valve bodies and press plates. The usual heat treatment for CF8M is solid Solution by heating to more than 1900 °F (1040 °C), holding for sufficient time and then quenching in water or rapid cool by other means.