Duplex Stainless Steel Coil

Short Description:

Grade: ASTM A182 F53, A240, A276, A479, A789, A790, A815, A928, A988 SAE J405 etc.

Standard: AISI, ASTM, DIN, EN, GB, ISO, JIS

Length: 2000mm, 2438mm, 3000mm, 5800mm, 6000mm, or as customer requirement

Width: 20mm – 2000mm, or as customer requirement

Thickness: 0.1mm -200mm

Surface: 2B 2D BA(Bright Annealed) No1 No3 No4 No5 No8 8K HL(Hair Line)

Price Term: CIF CFR FOB EXW

Delivery time: Within 10-15 days after confirming the order

Payment term: 30% TT as deposit and the balance against a copy of B/L or LC

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Overview of Duplex Stainless Steel

Super duplex stainless steel is differentiated from standard duplex grades by its significantly improved corrosion-resistant properties. It is a highly alloyed material with elevated concentrations of anti-corrosive elements such as chromium (Cr) and molybdenum (Mo). The primary super duplex stainless steel grade, S32750, comprises as much as 28.0% chromium, 3.5% molybdenum, and 8.0% nickel (Ni). These components impart exceptional resistance to corrosive agents, including acids, chlorides, and caustic solutions.

Generally, super duplex stainless steels build upon the established benefits of duplex grades with enhanced chemical stability. This makes it an ideal grade for fabricating critical components in the petrochemical sector, such as heat exchangers, boilers, and pressure vessel equipment.

Mechanical Properties of Duplex Stainless Steel

Grades	ASTM A789 Grade S32520 Heat-Treated	ASTM A790 Grade S31803 Heat-Treated	ASTM A790 Grade S32304 Heat-Treated	ASTM A815 Grade S32550 Heat-Treated	ASTM A815 Grade S32205 Heat-Treated
Elastic Modulus	200 GPa	200 GPa	200 GPa	200 GPa	200 GPa
Elongation	25 %	25 %	25 %	15 %	20 %
Tensile Strength	770 MPa	620 MPa	600 MPa	800 MPa	655 MPa
Brinell hardness	310	290	290	302	290
Yield Strength	550 MPa	450 MPa	400 MPa	550 MPa	450 MPa
Thermal expansion coefficient	1E-5 1/K	1E-5 1/K	1E-5 1/K	1E-5 1/K	1E-5 1/K
Specific Heat capacity	440 – 502 J/(kg·K)	440 – 502 J/(kg·K)	440 – 502 J/(kg·K)	440 – 502 J/(kg·K)	440 – 502 J/(kg·K)
Thermal Conductivity	13 – 30 W/(m·K)	13 – 30 W/(m·K)	13 – 30 W/(m·K)	13 – 30 W/(m·K)	13 – 30 W/(m·K)

Classification of Duplex Stainless Steel

l The first type is low alloy type, with the representative grade of UNS S32304 (23Cr-4Ni-0.1N). The steel does not contain molybdenum, and the PREN value is 24-25. It can be used instead of AISI304 or 316 in stress corrosion resistance.

l The second type belongs to medium alloy type, the representative brand is UNS S31803 (22Cr-5Ni-3Mo-0.15N), the PREN value is 32-33, and its corrosion resistance is between AISI 316L and 6% Mo+N austenitic stainless steel.

l The third type is of high alloy type, which generally contains 25% Cr, molybdenum and nitrogen, and some also contain copper and tungsten. The standard grade UNSS32550 (25Cr-6Ni-3Mo-2Cu-0.2N), PREN value is 38-39, and the corrosion resistance of this type of steel is higher than that of 22% Cr duplex stainless steel.

l The fourth type is super duplex stainless steel, which contains high molybdenum and nitrogen. The standard grade is UNS S32750 (25Cr-7Ni-3.7Mo-0.3N), and some also contain tungsten and copper. The PREN value is greater than 40, which can be applied to harsh medium conditions. It has good corrosion resistance and mechanical comprehensive properties, which can be comparable with super austenitic stainless steel.

Benefits of Duplex Stainless Steel

As stated above, Duplex is normally performing better than individual steel types found within its microstructure. Better said, the combination of positive characteristics coming from austenite and ferrite elements provides a better overall solution for a great number of different production situations.

l Anti-corrosive properties – The effect of molybdenum, chromium, and nitrogen on corrosion resistance of Duplex alloys is immense. Several Duplex alloys can match and exceed anti-corrosive performance of popular austenitic grades including 304 and 316. They are especially effective against crevice and pitting corrosion.

l Stress corrosion cracking – SSC comes as a result of several atmospheric factors – temperature and humidity being the most evident ones. Tensile stress just adds to the problem. Normal austenitic grades are highly susceptible to stress corrosion cracking – Duplex stainless steel is not.

l Toughness – Duplex is tougher than ferritic steels – even at lower temperatures while it does not actually match the performance of austenitic grades in this aspect.

l Strength – Duplex alloys can be up to 2 times stronger than both austenitic and ferritic structures. Higher strength means that metal remains firm even with reduced thickness which is especially important for reducing weight levels.