2507 vs 904L Stainless Steel: Which Is Better for Corrosion Resistance?

When selecting stainless steel for a highly corrosive application, 2507 and 904L are two high-performance grades frequently considered. Both offer substantially higher corrosion resistance than conventional 304/304L and 316/316L stainless steel, but they are designed around different corrosion challenges.

 

What is 2507 super duplex stainless steel?

2507 (UNS S32750 / EN 1.4410) is a super duplex stainless steel with approximately 25% chromium, 7% nickel, 4% molybdenum and nitrogen. Its combination of high alloy content and duplex microstructure gives it excellent resistance to chloride-induced pitting, crevice corrosion and stress corrosion cracking (SCC), together with very high mechanical strength.

 

What is 904L austenitic stainless steel?

904L (UNS N08904 / EN 1.4539) is a high-alloy austenitic stainless steel containing approximately 20% chromium, 24% nickel, 4.3% molybdenum and about 1.4% copper. It was developed particularly for aggressive chemical environments and is well known for its resistance to sulfuric acid and other corrosive process media.

 

2507 vs 904L Stainless Steel: Standards

Feature	Super Duplex 2507	Super Austenitic 904L
UNS Designation	S32750	N08904
EN Designation	1.4410	1.4539
Common Name	Alloy 2507	Alloy 904L
Microstructure	Dual Phase (50% Ferrite / 50% Austenite)	Single Phase (Austenitic)

 

2507 vs 904L Stainless Steel: Chemical Composition (%)

904L relies on high Nickel and Copper, while 2507 relies on high Chromium, Molybdenum, and Nitrogen.

Element	2507 (S32750)	904L (N08904)
Chromium (Cr)	24.0 – 26.0	19.0 – 23.0
Nickel (Ni)	6.0 – 8.0	23.0 – 28.0
Molybdenum (Mo)	3.0 – 5.0	4.0 – 5.0
Nitrogen (N)	0.24 – 0.32	0.10 max
Copper (Cu)	0.50 max	1.0 – 2.0
Carbon (C)	0.030 max	0.020 max
Iron (Fe)	Balance	Balance

 

2507 vs 904L Stainless Steel: Mechanical Properties

Property	2507 (Typical)	904L (Typical)
Tensile Strength (UTS)	≥ 800 MPa (116 ksi)	≥ 490 MPa (71 ksi)
Yield Strength (0.2%)	≥ 550 MPa (80 ksi)	≥ 220 MPa (32 ksi)
Elongation (%)	25% min	35% min
Hardness (Rockwell C)	~32 HRC max	~70-90 HRB
Impact Toughness	Good (down to -50°C)	Excellent (Cryogenic)

 

2507 vs 904L: Which Has Better Pitting Resistance?

For chloride-induced pitting, 2507 generally has the advantage.

A commonly used screening parameter is the Pitting Resistance Equivalent Number (PRE/PREN):

PRE = %Cr + 3.3 × %Mo + 16 × %N

This formula is useful for comparing the potential resistance to localized corrosion in chloride-containing environments, although PRE should not be treated as a complete corrosion prediction model. Actual performance also depends on microstructure, surface condition, welding, temperature and environment.

Grade	Cr	Mo	N	Approx. PRE
316L	17.2	2.1	-	~24
904L	19.8	4.3	-	~34
2507	25.0	4.0	0.27	~42–43
254 SMO	20.0	6.1	0.20	~43

 

2507 vs 904L for Stress Corrosion Cracking

2507 super duplex steel features a dual-phase microstructure consisting of approximately 50% austenite and 50% ferrite. This mixed microstructure inhibits crack propagation, providing excellent resistance to chloride stress corrosion cracking, even under high-temperature and high-pressure conditions. 904L super austenitic steel contains high levels of nickel (23–28%) and molybdenum to resist both general and localized corrosion, and its resistance to stress corrosion cracking (SCC) is far superior to that of standard 300-series austenitic steels (such as 316L).

 

Is 904L superior to 2507 in sulfuric acid service?

Yes, in pure or general sulfuric acid service, 904L typically outperforms 2507 because its specific chemical composition-including the addition of copper-is specifically designed to resist sulfuric acid corrosion.

Condition	904L	2507
0–100% H₂SO₄, ≤35°C	<0.1 mm/y - Excellent corrosion resistance	Acceptable only at low concentrations, generally <20%
10% H₂SO₄, 80°C	<0.1 mm/y - Excellent resistance	>1.0 mm/y - Severe corrosion
50% H₂SO₄, 80°C	Limited service - Application dependent	Not recommended
93–98% H₂SO₄, 95–115°C	~0.17 mm/y - Suitable under controlled conditions	Not recommended

 

2507 vs. 904L: Cost

Both are high-end specialty stainless steels containing significant amounts of expensive elements such as nickel (Ni) and molybdenum (Mo). 904L has an exceptionally high nickel content (approximately 24%–26%), whereas 2507 has a lower nickel content (approximately 6%–8%) but higher levels of chromium (25%) and molybdenum (4%). Under standard market conditions, the high nickel content of 904L sometimes results in a slightly higher raw material base price compared to 2507-and a price far exceeding that of 304 or 316L. 

 

If you would like to narrow down the options to determine the best solution,
please let me know: Which specific chemicals or liquids are involved?
What is the operating temperature?
Is the component subjected to mechanical stress or pressure?

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FAQ

Is 2507 suitable for seawater environments?
Yes. 2507 offers exceptional resistance to pitting, crevice corrosion, and chloride stress corrosion cracking (SCC), making it widely used in applications such as seawater cooling, desalination, and offshore operations.

 

Which has higher strength: 2507 or 904L?
2507 has significantly higher strength. Under standard reference conditions, the minimum yield strength of 2507 is approximately 550 MPa, whereas that of 904L is around 240 MPa.

 

Which material is better suited for the oil and gas industry?
For offshore and subsea operations involving chlorides, 2507 is generally the superior choice. In "sour service" environments, material selection must also account for H₂S content, temperature, pressure, and relevant NACE/ISO standard requirements.

 

What is the difference between 2507 and 2205?
2507 is a super duplex stainless steel; it features higher chromium (Cr), molybdenum (Mo), and nitrogen (N) content and offers superior resistance to localized corrosion compared to standard 2205. The Pitting Resistance Equivalent (PRE) of 2507 exceeds 42.5, while that of 2205 exceeds 30.