Super duplex stainless introduction
Duplex Stainless Steel (DSS) refers to stainless steel with 50% of ferrite and 50% of austenite, and generally requires a minimum content of 30% less one. In the case of lower C, Cr content of 18% to 28%, Ni content of 3% to 10%. Some steel also contains Mo, Cu, Nb, Ti, N and other alloying elements.
Duplex Stainless Steelcastings details
This kind of steel combines the characteristics of both austenitic stainless and ferritic stainless steel. Compared with ferrite, the steel has higher plasticity and toughness, no brittleness at room temperature, significantly improved intergranular corrosion resistance and weldability, and at the same time retains the characteristics of 475 ℃ brittleness, high thermal conductivityand superplasticity of iron stainless steel. Compared with the austenitic stainless steel, high strength and resistance to intergranular corrosion and chloride stress corrosion significantly improved. Duplex stainless steel has excellent corrosion resistance properties, and also a nickel-saving stainless steel.
Duplex stainless steel has the following performance characteristics
1. Has good corrosion resistance and wear and tear corrosion. In some corrosive media conditions, suitable for the pumps, valves and other power equipment.
2. Good mechanical properties. High strength and fatigue strength, yield strength is 2 times of 18-8 type austenitic stainless steel. Elongation rate of solid solution reached 25%, toughness AK (V-notch) is more than 100J
3. Good solderability, small hot cracking tendency, usually don’t need preheating before welding, and don’t need heat treatment after welding, can weld with 18-8 type austenitic stainless steel or carbon steel.
4. Duplex stainless steels with low Cr (18% Cr) hot working temperature range are wider than 18-8 austenitic stainless steels and have low resistance. They can be directly rolled to produce billets without forging. Duplex stainless steels with high chromium (25% Cr) are slightly more difficult to hot-work than austenitic stainless steels and can produce boards, tubes and wires.
5. Compared with austenitic stainless steel, the thermal conductivity is large, the coefficient of linear expansion is small, suitable for lining the equipment and the production of composite board. Also suitable for the production of heat exchanger die, heat transfer efficiency is higher than austenitic stainless steel
6. There are still a variety of brittle tendencies of high chromium ferritic stainless steels and should not be used at working conditions above 300 ° C. the lower chromium content of Duplex stainless steel, the smaller harm of σ and other brittle phase.