1.2507 Super Duplex Steel — Grades F53 & S32750

Sandeep Khandelwal

Aug 7

2 min read

What is 1.2507 Super Duplex Steel?

1.2507 is the European (Werkstoff) designation for super duplex stainless steel, more widely known under its American equivalents UNS S32750 and ASTM/ASME F53. This grade belongs to the super duplex family, combining a balanced austenitic-ferritic microstructure that delivers exceptional strength alongside outstanding resistance to pitting, crevice, and stress corrosion cracking. At Supreme Steel, 1.2507 / S32750 / F53 is one of our most requested grades for offshore, marine, and chemical processing applications.

Chemical Composition

Element	Composition (%)
Chromium (Cr)	24.0 – 26.0
Nickel (Ni)	6.0 – 8.0
Molybdenum (Mo)	3.0 – 5.0
Nitrogen (N)	0.24 – 0.32
Carbon (C)	0.03 max
PREN	≥ 40

Mechanical Properties

Property	Typical Value
Tensile Strength	800 MPa min
Yield Strength (0.2% offset)	550 MPa min
Elongation	15% min
Hardness	≤ 32 HRC
Impact Toughness (-46°C)	Excellent (Charpy V-notch qualified)

Key Advantages

■ Superior Corrosion Resistance — a PREN value above 40 makes this grade highly resistant to chloride-induced pitting and crevice corrosion

■ High Mechanical Strength — roughly double the yield strength of standard austenitic stainless steels, allowing thinner sections and reduced weight

■ Excellent Weldability — a well-balanced microstructure supports reliable fabrication using standard duplex welding procedures

■ Long Service Life — ideal for critical components exposed to seawater, sour gas, and aggressive process chemicals

Common Applications

■ Offshore oil & gas platforms and subsea equipment

■ Seawater cooling systems and desalination plants

■ Chemical and petrochemical processing equipment

■ Pulp and paper industry components

■ High-pressure pipe fittings, flanges, and valves (F53)

Available Product Forms at Supreme Steel

Supreme Steel supplies 1.2507 / S32750 / F53 super duplex steel in round bars, plates, sheets, pipes, tubes, fittings, and forged flanges — all backed by full mill test certificates (EN 10204 3.1/3.2) and third-party inspection on request.