Duplex steel/Super duplex steel Stainless steel pipe is with austenitic + ferritic duplex structure, so its performance characteristics have the characteristics of austenitic stainless steel and ferritic stainless steel, is a class of high strength and high corrosion resistance of stainless steel. Usually, in the case of low carbon C content, the Cr content is 18% to 28%, and the Ni content is 3% to 10%. Some steels also contain Mo, Cu, Nb, Ti, N and other alloying elements. Compared with ferrite, plasticity, toughness is higher, no room temperature brittleness, intergranular corrosion resistance and welding performance are significantly improved, while also maintaining the ferritic stainless steel 475℃ brittleness and high thermal conductivity, with superplasticity and other characteristics. Compared with austenitic stainless steel, the yield strength is significantly improved, and the resistance to intergranular corrosion, stress corrosion, corrosion fatigue and abrasion is significantly improved.

Duplex stainless steel pipe fittings can generally be divided into four categories:

(1), low alloy type pipe fitting -- representative brand is UNS S32304 (23Cr-4Ni-0.1N), corrosion resistance index PREN value (PREN=Cr%+3.3×Mo%+16×N%) is 24 ~ 25, The low-alloy UNS S32304 does not contain molybdenum and can be used instead of ISI304 or 316 in stress corrosion resistance.

(2), medium alloy type pipe fitting - representative brand is UNS S31803 (22Cr-5Ni-3Mo-0.15N), corrosion resistance index PREN value is 32 ~ 33, medium alloy type UNS S31803 corrosion resistance between AISI 316L and 6%Mo+N austenitic stainless steel.

(3), high alloy pipe fittings - standard grade UNS S32550 (25Cr-6Ni-3Mo-2Cu-0.2N), corrosion resistance index PREN is 38 ~ 39, High alloy type, generally containing 25%Cr, also contains molybdenum and nitrogen, and some also contain copper and tungsten, the corrosion resistance of this type of steel is higher than 22%Cr duplex stainless steel pipe fittings.

(4), super duplex stainless steel pipe fittings -- standard grade UNS S32750 (25Cr-7Ni-3.7Mo-0.3N), corrosion resistance index PREN value > 40, Super duplex stainless steel type, containing high molybdenum and nitrogen, some also containing tungsten and copper, can be applied to harsh media conditions, has good corrosion resistance and mechanical properties, can be compared with super austenitic stainless steel pipe fittings.

Our team at Hebei Longheng Pipeline Equipement  Co., Ltd. is well trained and has extensive experience in maintaining and producing various types of steel. Whether you have a large construction project or need industrial machinery parts, our team of steel manufacturing consultants will ensure that your project has the parts you need, when you need them.