S32760 vs S32750 Super Duplex Stainless Steel: Composition, Properties and Selection

S32760 vs S32750 Super Duplex Stainless Steel: Composition, Properties and Selection

S32760 vs S32750 is not a comparison between an ordinary stainless steel and a universally superior replacement. Both are 25% chromium super duplex stainless steel grades developed for high strength and resistance to chloride-related pitting, crevice corrosion and stress-corrosion cracking. The main distinction is their alloy design: S32760 includes specified additions of copper and tungsten, while S32750 is primarily balanced around chromium, molybdenum and nitrogen.

For buyers, the correct choice depends on the process environment, product form, governing standard, project approval, fabrication route and required test documentation. A material should not be substituted merely because both grades have a PREN above 40 or are described commercially as “super duplex.”

View S32760 Duplex Steel Bar

S32760 and S32750 at a Glance

Chemical Composition: What Is the Main Difference?

The comparison below shows the elements that most clearly explain the difference. The S32750 column uses representative nominal values published for SAF 2507 bar. The S32760 column shows the published range for Alloy 32760. These figures explain alloy design; the applicable material specification and mill test certificate control acceptance for an actual order.

The presence of copper and tungsten is therefore the clearest chemistry-based answer to “What is the difference between S32750 and S32760?” It does not prove that S32760 will outperform S32750 in every fluid, temperature or fabricated condition. Welding, heat treatment, surface condition, inclusions, phase balance and component geometry also influence performance.

PREN: Useful Screening Index, Not a Service Guarantee

PREN, or Pitting Resistance Equivalent Number, is a composition-based index used to compare resistance to localized corrosion. A common expression is:

Alleima reports a minimum PRE value of 41 for SAF 2507 bar using this expression. For tungsten-bearing S32760, some standards and technical sources use a modified expression:

The ZERON 100 data book reports PREN above 41 using the tungsten-inclusive expression. Values produced by different formulas should not be compared as though they were generated on an identical basis. PREN also does not model crevice geometry, deposits, welding condition, temperature, fluid chemistry, velocity or galvanic effects. It is a screening tool—not a guaranteed service-life calculation.

Mechanical Properties and Delivery Condition

Published room-temperature data show that both grades can provide high strength in the solution-annealed condition. The examples below are not universal acceptance values for every diameter, product form or specification.

A quotation should identify whether the material is bar, forging, plate, tube, pipe or a finished part. Section size, solution-annealing practice, cold work and the selected product standard can change the required or achievable properties. Compare supplier offers against the same product form and acceptance basis.

Which Grade Is Better for Seawater?

Both S32750 and S32760 are used in aggressive chloride-bearing environments, including seawater-related equipment. It is not technically sound to declare one grade “best for saltwater” without defining the service.

Questions that change the answer

If a design specification already requires S32760/F55 or S32750/F53, a supplier should not substitute the other grade without written engineering approval. Where either grade is technically permitted, compare corrosion data and qualification records for the actual product form, weld condition and service environment.

Typical Applications

ASTM Equivalent: Use the Product Form, Not One Universal Number

The question “What is the ASTM equivalent of UNS S32760?” needs a product-form answer. UNS identifies the composition, while ASTM specifications define requirements for particular forms and uses.

For a bar enquiry, review the available S32760 duplex steel bar and S32750 duplex steel bar pages, then state the required standard and complete acceptance criteria in the RFQ.

S32760 Bar RFQ Checklist

Frequently Asked Questions

What is S32760 material?

UNS S32760 is a 25% chromium super duplex stainless steel containing molybdenum, nitrogen, copper and tungsten. It is used where high strength and resistance to localized corrosion or chloride stress-corrosion cracking are required, subject to the actual service and product specification.

Is S32750 the same as 2507?

“2507” commonly refers to UNS S32750. SAF 2507 is a trade name associated with Alleima. For purchasing and certification, write the UNS grade and governing product standard rather than relying only on the shortened commercial name.

What is the ASTM equivalent of S32760?

There is no single ASTM number for every product form. ASTM A182 F55 identifies S32760 for covered forgings and forged components. Bars and shapes may be ordered to ASTM A276 or ASTM A479 when the product falls within their scope. Pipe and tube use different specifications.

What is the difference between S32750 and S32760?

Both are super duplex grades with broadly similar strength and high resistance to localized corrosion. The most visible chemistry difference is that S32760 specifies copper and tungsten additions. They also have different UNS and EN designations and different ASTM A182 forging grades: F53 for S32750 and F55 for S32760.

Can S32750 replace S32760?

Not automatically. A substitution requires review of the design code, corrosion environment, product form, mechanical requirements, material qualification, welding procedure and customer specification. Written engineering approval should be obtained before changing the grade.

Which grade is better for seawater?

Both can be candidates for seawater-related service. The correct choice depends on temperature, chlorination, crevice geometry, flow, deposits, welding, cathodic protection and the applicable project standard. Neither grade name alone guarantees suitability or service life.

Conclusion

S32750 and S32760 belong to the same super duplex family but are not identical grades. S32750—commonly called 2507—uses a chromium-molybdenum-nitrogen alloy balance, while S32760 adds specified copper and tungsten. Their published strength levels can be similar, so the decision often turns on project specifications, corrosion conditions, approvals, product availability and qualification history rather than one headline property.

For an S32760 bar quotation, identify the complete grade, product specification, diameter, length, condition, surface, service environment and inspection requirements. This gives the supplier a consistent technical basis and reduces the risk of receiving an unsuitable “equivalent” material.