1.4410 vs 1.4501 Super Duplex Stainless Steel: What’s the Difference?

Two Super Duplex Grades Explained

For demanding duties such as offshore platforms, desalination plant and chemical process systems, two super duplex stainless steels appear on almost every shortlist: 1.4410 and 1.4501. Both combine high strength with outstanding resistance to pitting, crevice corrosion and chloride stress corrosion cracking, and both are widely available in plate, pipe, tube and bar.

The distinction between them is subtle but real, and it comes down to deliberate alloying additions. This comparison sets out composition, mechanical properties, corrosion behaviour and weldability so that procurement and engineering teams can decide which grade earns its place in a given project.

Grade identification and product standards

Parameter1.44101.4501 EN designationX2CrNiMoN25-7-4X2CrNiMoCuWN25-7-4 UNS numberS32750S32760 Product standardsASTM A240, ASTM A790ASTM A240, ASTM A790 Material typeSuper duplex stainless steelSuper duplex stainless steel with tungsten and copper

Both grades are covered by the same ASTM product specifications for plate, sheet and strip (ASTM A240) and for seamless and welded ferritic–austenitic pipe (ASTM A790), so they can be ordered against a common documentation set. The 1.4501 chemistry adds tungsten and copper, and that addition is the origin of nearly every practical difference between the two.

Chemical Composition: Tungsten and Copper Make the Difference

Element	1.4410 (S32750)	1.4501 (S32760)
Chromium (Cr)	24.0–26.0%	24.0–26.0%
Nickel (Ni)	6.0–8.0%	6.0–8.0%
Molybdenum (Mo)	3.0–5.0%	3.0–4.0%
Nitrogen (N)	0.24–0.35%	0.20–0.30%
Tungsten (W)	-	0.5–1.0%
Copper (Cu)	-	0.5–1.0%

Chromium, nickel and nitrogen levels are closely comparable, with 1.4410 permitted a slightly wider molybdenum range and a marginally higher nitrogen ceiling. The decisive difference is the 0.5–1.0% tungsten and 0.5–1.0% copper present only in 1.4501. Tungsten raises resistance to localised attack because it contributes to the pitting resistance of the passive film, and copper improves performance in reducing acid environments while refining the microstructure in the heat-affected zone after welding.

Mechanical Properties Compared

Property	1.4410	1.4501
Yield strength Rp0.2	≥ 550 MPa	≥ 550 MPa
Tensile strength Rm	750–930 MPa	750–930 MPa
Elongation	≥ 25%	≥ 25%
Hardness (HBW)	≤ 290	≤ 290

On paper the two grades are identical in the solution-annealed condition, and in practice the required minimum values are the same. The meaningful engineering difference appears in welded construction rather than in the mill certificate: the tungsten and copper in 1.4501 give the heat-affected zone better structural stability, so a welded joint in 1.4501 retains more of its corrosion resistance than the equivalent joint in 1.4410.

Corrosion Resistance and Welding Behaviour

Both grades offer excellent resistance to pitting, crevice corrosion and chloride stress corrosion cracking, and both are designed for seawater and high-chloride service. Where the media become more aggressive, for example in hydrogen sulphide containing streams or at elevated temperature and pressure, the copper and tungsten additions in 1.4501 provide a measurable advantage in localised corrosion resistance.

Weldability is good in both cases and both are suitable for conventional TIG and MIG processes. The differences are worth noting for fabrication planning:

1.4501 shows better structural stability in the heat-affected zone and stronger post-weld corrosion resistance, which suits complex welded assemblies and heavy-section joints where the thermal cycle cannot be tightly controlled.

1.4410 welds well but demands stricter control of heat input and interpass temperature to prevent phase imbalance and the localised corrosion that follows from it.

Redundancy in fabrication. Where a project involves large volumes of welding or welding in difficult positions, the additional safety margin of 1.4501 reduces the risk carried by the fabrication contractor.

Shared handling rules. Both grades require clean, dedicated stainless tools, controlled heat input and a properly qualified welding procedure to preserve the ferrite–austenite balance.

Selection Guidance for Procurement

Because the minimum mechanical properties are the same and both grades are available in the same product forms, selection usually turns on corrosion severity, weld volume and price. Where the environment is severe, where hydrogen sulphide or high pressure is present, or where a large amount of welding will be performed in the field, 1.4501 justifies its premium. Where the duty is demanding but well characterised, and weld quality can be controlled in a shop environment, 1.4410 delivers comparable strength with a simpler alloy chemistry.

In either case, ask for the mill test report to confirm composition against the ordered grade, verify that heat treatment has produced the required phase balance, and confirm that welding procedures have been qualified for the actual thickness and position used in fabrication.

FAQ: 1.4410 vs 1.4501

Q: What is the main difference between 1.4410 and 1.4501?
1.4501 contains 0.5–1.0% tungsten and 0.5–1.0% copper, which are absent from 1.4410. These additions improve localised corrosion resistance and post-weld structural stability.

Q: Are their mechanical properties different?
No. Both require a minimum yield strength of 550 MPa, a tensile range of 750–930 MPa, at least 25% elongation and a maximum hardness of 290 HBW.

Q: Which grade performs better after welding?
1.4501 generally does, because tungsten and copper stabilise the heat-affected zone and preserve more of the parent metal corrosion resistance in the as-welded condition.

Q: Do both grades meet the same standards?
Yes. Both are supplied against ASTM A240 for plate, sheet and strip and ASTM A790 for seamless and welded pipe, with UNS numbers S32750 and S32760 respectively.

Q: When should 1.4501 be preferred over 1.4410?
In more aggressive media such as hydrogen sulphide bearing or high-temperature, high-pressure systems, and in projects with heavy or complex welding where extra corrosion insurance is valuable.

Q: Is 1.4410 easier to obtain?
1.4410 (S32750) is the more widely stocked of the two grades, so lead times are often shorter unless the project specification calls for the tungsten-bearing grade.