Guide to EN 1.4501 Corrosion-Resistant Alloy

Apr 03, 2026

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1.4501 stainless steel, widely known by its trade name Zeron 100 (and also as UNS S32760 or F55), is a super duplex stainless steel enhanced with tungsten and copper. It represents the highest echelon of duplex alloys, offering an extraordinary combination of immense strength, exceptional corrosion resistance-especially against pitting and stress corrosion cracking-and improved weldability. The addition of tungsten and copper provides superior performance in aggressive environments, making it the ultimate choice for the most demanding offshore, chemical, and subsea applications.

Standard	Equivalent Grade
EN (Europe)	1.4501
ASTM/AISI (USA)	F55, UNS S32760 (Zeron 100)
Common Name	Zeron 100

Element	C	Si	Mn	P	S	Cr	Ni	Mo	N	W	Cu
Content (%)	≤ 0.03	≤ 1.0	≤ 1.0	≤ 0.03	≤ 0.01	24.0 - 26.0	6.0 - 8.0	3.0 - 4.0	0.20 - 0.30	0.50 - 1.00	0.50 - 1.00

Property	Yield Strength (Rp0.2)	Tensile Strength (Rm)	Elongation (A)	Hardness (HB)	Impact (J)
Typical Value	≥ 550 MPa	750 - 1000 MPa	≥ 25%	≤ 300	≥ 45 (-40°C)

Unmatched Corrosion Resistance: Possesses an exceptionally high Pitting Resistance Equivalent Number (PREN > 40), offering best-in-class resistance to pitting, crevice corrosion, and stress corrosion cracking in hot, chloride-laden environments. The tungsten addition further enhances pitting resistance at elevated temperatures.

Extremely High Strength: Delivers yield strength approximately double that of standard austenitic steels, enabling significant weight and cost savings in pressure vessels and structural components.

Enhanced Weldability: The balanced composition, including tungsten and copper, promotes a stable microstructure in welds, making it more forgiving to weld than some other super duplex grades with similar corrosion resistance.

Excellent Sour Service Resistance: Outstanding performance in H₂S-containing environments, making it ideal for oil and gas applications meeting NACE MR0175/ISO 15156 requirements.

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

Chemical & Process: Reactors, columns, heat exchangers, and piping handling aggressive mixtures of acids, chlorides, and other corrosive media.

Pollution Control: FGD scrubbers, absorber towers, and critical ductwork in power plant desulfurization systems.

Pulp & Paper: High-pressure and high-temperature digesters and bleaching equipment.

Marine Engineering: Propeller shafts, seawater pumps, and valve systems.

Desalination: High-pressure piping and evaporator systems.

While both are super duplex grades, Zeron 100 contains additional alloying elements-tungsten (W) and copper (Cu)-that 2507 does not. Tungsten further enhances pitting and crevice corrosion resistance, particularly at elevated temperatures, and improves the stability of the microstructure during welding by retarding the formation of detrimental intermetallic phases. Copper enhances resistance to reducing acids like sulfuric acid. This gives Zeron 100 a performance edge in the most complex and severe corrosive environments, especially those involving both chlorides and acids, or where higher operating temperatures are encountered. It also offers improved toughness at low temperatures and better resistance to sulfide stress cracking in sour service.

Welding Zeron 100 follows similar principles (controlling heat input, using over-alloyed filler) but benefits from its enhanced composition. The tungsten content helps retard the formation of detrimental intermetallic phases (sigma, chi) in the heat-affected zone (HAZ), providing a wider "processing window" and reducing the risk of embrittlement. Recommended heat input is typically 0.5-2.0 kJ/mm, with interpass temperature below 150°C. Matching filler metals (e.g., Zeron 100X) are available, or over-alloyed nickel-based fillers may be used for highest corrosion resistance. It still requires careful procedure qualification but is generally considered to have better weldability than other super duplex alloys of similar corrosion resistance, making it more forgiving in fabrication.

Zeron 100 is approved for use under numerous international standards and by major certification bodies. It meets the requirements of NACE MR0175/ISO 15156 for sour service applications in oil and gas. It is approved for pressure vessel manufacture under ASME Boiler and Pressure Vessel Code (Section VIII, Division 1) and for piping under ASME B31.3. It also meets the requirements of NORSOK M-630 for offshore applications. Material is typically supplied with EN 10204 3.1 certification and can be provided with additional third-party inspections by major classification societies (DNV, ABS, Lloyd's, BV) for marine and offshore applications.

GNEE Steel supplies the premium super duplex grade Zeron 100 (1.4501/UNS S32760) for the most critical and corrosive applications. We provide plate, pipe, fittings, bar, and forging forms with full traceability and comprehensive certifications (EN 10204 3.1, NACE, etc.). If you have any requirements, please feel free to contact us.