What is 1.4507 Stainless Steel?

1.4507 stainless steel, commonly known as 2507 HD (High Duplex) or UNS S32707, is a super duplex stainless steel with an enhanced balance of ferritic and austenitic phases. It offers even higher strength and corrosion resistance than standard 2507, particularly in extremely aggressive chloride and acidic environments, making it ideal for demanding offshore, chemical, and subsea applications.

 

This enhanced super duplex grade is standardized under key international designations.

Standard	Equivalent Grade
EN (Europe)	1.4507
ASTM/AISI (USA)	2507 HD, UNS S32707
Common Name	2507 HD

Its composition includes higher chromium, molybdenum, and nitrogen for superior performance.

Element	C	Si	Mn	P	S	Cr	Ni	Mo	N
Content (%)	≤ 0.03	≤ 0.80	≤ 1.2	≤ 0.035	≤ 0.02	24.0 - 26.0	6.0 - 8.0	3.0 - 4.5	0.24 - 0.32

It provides extreme strength and excellent toughness even in harsh conditions.

Property	Yield Strength (Rp0.2)	Tensile Strength (Rm)	Elongation (A)	Hardness (HB)	Impact (J)
Typical Value	≥ 550 MPa	750 - 1000 MPa	≥ 25%	≤ 310	≥ 80 (20°C)

 

Key Characteristics and Applications of 1.4507 / 2507 HD

Exceptional Corrosion Resistance: Possesses a very high Pitting Resistance Equivalent Number (PREN > 40), offering superior resistance to pitting, crevice corrosion, and stress corrosion cracking in aggressive chloride and acidic environments.

Very High Strength: Its duplex structure provides extremely high yield and tensile strength, enabling lighter and more cost-effective designs for pressure-containing parts.

Good Erosion and Wear Resistance: The ferritic phase contributes to good resistance against erosion-corrosion and abrasive wear.

 

Primary Applications:

Subsea & Offshore: Christmas trees, manifolds, flowlines, and umbilicals in deepwater oil & gas production.

Chemical Processing: Reactors, heat exchangers, and piping for highly corrosive acids and chlorides.

Desalination & FGD Plants: High-pressure RO membranes, evaporator tubes, and scrubber systems.

Pulp & Paper Industry: Digesters and bleaching equipment.

 

How does 2507 HD (1.4507) differ from standard Super Duplex 2507 (1.4410)?
2507 HD is an enhanced version with tighter compositional control and slightly higher alloy content, providing even better corrosion resistance and mechanical properties. It is often specified for the most severe service conditions where standard 2507 may approach its limits, particularly in terms of pitting and crevice corrosion resistance at elevated temperatures.

 

What are the critical factors for welding 2507 HD stainless steel?
Welding 2507 HD requires stringent control to maintain the optimal 50/50 ferrite-austenite balance in the weld metal and heat-affected zone (HAZ). Key practices include using over-alloyed filler metals (e.g., 25.10.4.L), strict control of heat input to avoid excessive ferrite formation or precipitation of brittle intermetallic phases, and ensuring adequate shielding gas (typically Ar + 30% N2) to maintain nitrogen levels. Post-weld cooling rates must be controlled, and the material should not be held in the critical temperature range (approx. 600-1000°C) for extended periods.

 

Looking for a Reliable Supplier of 1.4507 / 2507 HD Stainless Steel?
GNEE Steel supplies premium enhanced super duplex 2507 HD (1.4507) stainless steel in plate, pipe, fittings, and bar forms for the most challenging corrosive and high-pressure applications. We provide full material traceability and certifications to ensure performance. If you have any requirements, please feel free to contact us.