Duplex Steel

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Super Duplex Steel

Super Duplex Steel is a high-performance alloy combining the excellent corrosion resistance of austenitic stainless steel with the high strength of ferritic grades. Containing elevated levels of chromium, molybdenum, and nitrogen, it offers exceptional resistance to pitting, crevice corrosion, and stress corrosion cracking in aggressive chloride-rich environments. Grades such as 2507 and Ferralium® 255 are widely used in demanding industries including offshore oil & gas, chemical processing, desalination, and marine engineering, where both strength and corrosion resistance are critical.

Super Duplex Steel Products and their Grades

Product Grades
Super Duplex Steel ASTM A182 F2507, ASTM A182 F255, ASTM A182 F53, ASTM A182 F55
Pipes A790
Tubes A789
Pipe Fitting A815
Forged Fitting A182 (F51, F53, F55, F61, F54, F60, F70)
Flanges A182 (F51, F53, F55, F61, F54, F60, F70)

Chemical Composition of Super Duplex Steel

Grade C (%) Mn (%) Si (%) P (%) S (%) Cr (%) Ni (%) Mo (%) N (%) Cu (%)
Super Duplex 2507 0.03 max 1.20 max 0.80 max 0.035 max 0.020 max 24.0 – 26.0 6.0 – 8.0 3.0 – 5.0 0.24 – 0.32 0.50 max
Super Duplex 255 (Ferralium® 255) 0.04 max 1.50 max 1.00 max 0.040 max 0.030 max 24.0 – 26.5 4.5 – 6.5 2.9 – 3.9 0.10 – 0.25 1.5 – 2.5

Mechanical Properties of Super Duplex Steel

Grade Tensile Strength (MPa) Yield Strength 0.2% Proof (MPa) Elongation (%) Hardness (HB)
Super Duplex 2507 800 min 550 min 25 min 310 max
Super Duplex 255 (Ferralium® 255) 750 – 850 550 – 620 15 – 25 290 max

Applications of Super Duplex Steel

Super duplex steel combines exceptional strength, superior corrosion resistance, and excellent resistance to chloride stress corrosion cracking, making it ideal for the most demanding environments such as deepwater oil & gas, desalination, and aggressive chemical processing industries.

Offshore & Subsea Equipment

Ideal for subsea pipelines, risers, manifolds, and umbilicals exposed to high pressure and corrosive seawater.

Chemical & Petrochemical Processing

Used in reactors, heat exchangers, and pressure vessels handling strong acids, chlorides, and other aggressive chemicals.

Marine Engineering

Applied in shipbuilding, propeller shafts, and seawater cooling systems for high pitting and crevice corrosion resistance.

Desalination Plants

Ideal for high-pressure evaporators, brine heaters, and seawater intake piping where saltwater corrosion is severe.

Power Generation

Used in flue gas desulfurization units, condensers, and high-temperature heat recovery systems.

Pulp & Paper Industry

Resists aggressive bleaching agents and high chloride process water in digesters and bleaching plants.