Super Austenitic Stainless Steel · 6.5% Molybdenum · 27% Chromium · Copper-Bearing

NAS 325N / UNS N08031 / EN 1.4562 Forging Parts

Published: 20 June 2016  |  Last updated: 21 August 2026  |  Technically reviewed by the Jiangyin Jiangnan Metal Co., Ltd. Metallurgical Engineering Team

NAS 325N is a super austenitic stainless steel containing nominally 31% nickel, 27% chromium, 6.5% molybdenum, 1.2% copper and 0.2% nitrogen, balance iron. This is the chemistry registered as UNS N08031 and standardised in Europe as EN 1.4562 (X1NiCrMoCu32-28-7), sold generically as Alloy 31. Its pitting resistance equivalent number of roughly 52 and measured critical pitting temperature of about 85 °C place it a full rung above the 6% molybdenum grades in chloride service. It is also separated from those grades by its acid resistance. The 27% chromium and the deliberate 1.0–1.4% copper addition make it one of the few stainless steels usable in hot sulfuric acid and wet-process phosphoric acid, duties that otherwise require a nickel-base alloy at several times the cost.

Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, manufactures NAS 325N in forged form to customer drawings: seamless rolled rings to 2,500 mm outside diameter, forged discs to 1,800 mm diameter, shafts to 8 m length, bars from Ø25 mm to Ø500 mm, and single pieces to 8,000 kg. Material is melted by EAF + AOD/VOD + ESR, supplied solution annealed at 1,150–1,180 °C and water quenched, and certified to EN 10204 3.1 as standard.

Trademark notice. NAS® and NAS 325N are designations of Nippon Yakin Kogyo Co., Ltd. Nicrofer® is a registered trademark of VDM Metals. ATI 31™ is a trademark of ATI Properties, LLC. Hastelloy® is a registered trademark of Haynes International, Inc. 254 SMO® is a registered trademark of Outokumpu. AL-6XN® is a registered trademark of ATI Properties. Incoloy® is a registered trademark of the Special Metals Corporation group. Material produced by those companies and sold under those brand names is theirs. Material produced by Jiangyin Jiangnan Metal Co., Ltd. is correctly described as UNS N08031 / EN 1.4562 / X1NiCrMoCu32-28-7, the same generic chemistry manufactured independently. We are not affiliated with, sponsored by, or endorsed by any of the trademark holders listed above.

What is NAS 325N (UNS N08031)?

NAS 325N is a super austenitic stainless steel. It is a fully austenitic iron-based alloy carrying enough molybdenum, chromium and nitrogen to behave, in corrosion terms, like a nickel alloy. Nippon Yakin Kogyo developed it; the same chemistry is registered internationally as UNS N08031 and standardised in Europe as EN 1.4562 / X1NiCrMoCu32-28-7, and is sold generically as Alloy 31 and under producer trade names including Nicrofer 3127 hMo and ATI 31.

The composition is built around four elements:

• Chromium at 26–28% is unusually high for an austenitic stainless steel and is the primary reason the alloy holds up in oxidising acids such as nitric, and in the oxidising conditions found in bleach and scrubber liquors.
• Molybdenum at 6.0–7.0% stabilises the passive film against chloride attack and carries resistance in reducing conditions where chromium alone is not enough.
• Nitrogen at 0.15–0.25% stabilises the austenite so that the high chromium and molybdenum do not push the structure toward ferrite or sigma, raises proof strength substantially, and contributes strongly to pitting resistance. Per weight percent it is the most efficient element in the PREN equation.
• Copper at 1.0–1.4% does little for chloride pitting but changes behaviour in sulfuric and phosphoric acid, where it shifts the corrosion potential into the passive region. This is why NAS 325N is specified for wet-process phosphoric acid plants and for sulfuric acid circuits in which 6% molybdenum grades without copper are not adequate.

The 30–32% nickel serves two purposes. It keeps the structure austenitic against the strongly ferrite-forming chromium and molybdenum, and it places the alloy far above the roughly 8–12% nickel band where austenitic stainless steels are most vulnerable to chloride stress corrosion cracking.

Fabrication trade-offs

The same chemistry that gives the corrosion resistance also makes the alloy harder to manufacture. The hot-working window is narrow and sits high. The alloy work hardens faster than 316L, so machining is slower and tooling wears more quickly. The high molybdenum makes it prone to sigma and chi phase precipitation if cooling through 1,000–600 °C is slow, which means heavy sections need a fast quench rather than a nominal one. And because there is no strengthening mechanism other than cold work, a designer cannot buy back section thickness with heat treatment.

None of this is a defect; it is what a PREN of 52 costs in an iron-based alloy. It is also the reason the grade is normally bought forged and solution annealed from a shop that runs it regularly, rather than machined from whatever plate is in stock.

NAS 325N forgings: supplier quick facts

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China, roughly two hours from the ports of Shanghai and Ningbo. The table below is the short answer to most sourcing questions about this grade.

What Forged Products Are Available in NAS 325N?

Jiangyin Jiangnan Metal produces NAS 325N through two routes. Rotationally symmetric parts with a hole (rings, sleeves, hollow bushings) are produced as seamless rolled rings: a forged billet is upset, pierced and expanded on a radial-axial ring mill so that the grain flow follows the circumference continuously. Everything else is open-die forged under the press and hammers, then machined.

One route-selection point matters specifically for a 6.5% molybdenum grade. A ring rolled to near-net section quenches faster and more uniformly than a thick solid block machined down afterwards, because the controlling section is thinner. On heavy pressure-retaining parts the benefit is metallurgical as well as commercial, since a thinner section is often what allows the quench to clear the sigma-phase window. Where geometry allows we propose the rolled-ring route for that reason and note it on the quotation.

• Seamless rolled rings
• Forged rings
• Forged flanges
• Forged shafts
• Forged round bars
• Forged discs
• Forged blanks
• Forged sleeves
• Forged bushings
• Hollow bars
• Tube sheets
• Forged tubes
• Forged blocks
• Valve bodies
• Valve seat rings
• Valve stems
• Forged nozzles
• Agitator shafts
• Pump casings
• Spindles

What Are the Equivalent Designations of NAS 325N?

Engineers arrive at this chemistry through several different naming systems, which is why the same alloy appears on drawings under at least six names. They are the same material. UNS N08031 is the safest designation to put on a purchase order, because it is generic, unambiguous and owned by nobody.

What Is the Chemical Composition of NAS 325N?

What Is the PREN of NAS 325N?

The pitting resistance equivalent number condenses a chloride-relevant chemistry into one comparable figure. The common form is PREN = %Cr + 3.3 × %Mo + 16 × %N. For a mid-specification NAS 325N heat:

PREN = 27.0 + 3.3 × 6.5 + 16 × 0.20 = 27.0 + 21.5 + 3.2 = 51.7 ≈ 52

Some producer literature, including the published ATI 31 datasheet for the same chemistry, uses the 30 × %N form of the equation. That form returns about 54 for the mid-specification heat above, and producers commonly quote ≈ 53 as the typical production value, reflecting an aim slightly below mid-range. Both conventions are in use, so state the formula whenever a minimum PREN is specified on an order. The two forms differ by more than two points on this grade. Across the full specification band, N08031 ranges from roughly 48 at the bottom corner to 55 at the top on the 16N form.

What PREN does not tell you

PREN ranks chloride pitting resistance and nothing else. Three limits matter in practice. First, crevice corrosion resistance always sits below pitting resistance, typically by 15–20 °C in critical-temperature terms, so gasket faces, threaded joints and deposits under biofouling govern real service rather than the flat surface the PREN describes. Second, PREN says nothing about acid resistance. The copper and the 27% chromium that make NAS 325N work in sulfuric and phosphoric acid contribute almost nothing to the number. Third, PREN assumes the material is properly solution annealed. A heat with a compliant certificate chemistry and sigma phase at the grain boundaries will pit like a much poorer alloy, because the molybdenum is locked in the precipitate rather than held in solution.

How Corrosion Resistant Is NAS 325N?

NAS 325N is one of a small number of alloys that performs well in both oxidising and reducing conditions, which is why it is chosen for process circuits where the chemistry changes along the line. Published immersion data for this chemistry gives a useful sense of scale.

Behaviour by medium

• Wet-process phosphoric acid. The headline application. WPA carries fluorides, chlorides and abrasive solids alongside the acid, and the combination defeats most stainless steels. NAS 325N resists both the corrosion and the erosion-corrosion that follows from the solids loading.
• Sulfuric acid. Good resistance across a wide concentration range including highly concentrated acid, thanks to the copper addition. This is the duty where the grade most clearly separates from copper-free 6Mo alloys.
• Nitric acid. The 26–28% chromium gives resistance in boiling azeotropic nitric acid, where molybdenum-rich nickel alloys such as C-276 perform poorly because molybdenum is unstable in strongly oxidising acid.
• Chlorine dioxide bleach liquor. Established in pulp and paper D-stage bleaching, where the combination of oxidising conditions, chlorides and low pH is hostile to 316L and 317L.
• Seawater, FGD and marine scrubbers. A CPT near 85 °C to ASTM G48 Method A puts it comfortably above the 6Mo family for chloride pitting. Crevices still govern: design them out.
• Sour service. Listed under NACE MR0175 / ISO 15156 in the solution annealed condition, subject to the standard's environmental limits on H₂S partial pressure, chloride level, temperature and elemental sulfur.
• Ore digestion and pressure oxidation. Used for autoclave internals, agitator shafts and nozzles in hydrometallurgical circuits combining acid, chlorides and abrasion.
• Where it is not suitable. Hot concentrated hydrochloric acid and hydrofluoric acid require a nickel alloy: C-276, C-22, Alloy 59 or B-3, depending on whether conditions are oxidising or reducing.

What Are the Mechanical Properties of NAS 325N?

Strength at temperature

The alloy is code-approved for pressure-retaining service. The table below gives the ASME Boiler and Pressure Vessel Code Section VIII Division 1 maximum allowable stresses published for this chemistry. They are useful for a first-pass wall thickness before a full code calculation.

What Are the Physical Properties of NAS 325N?

How Is NAS 325N Heat Treated?

There is exactly one correct final heat treatment: solution anneal at 1,150–1,180 °C (2,102–2,156 °F), then quench rapidly, normally in water. Nothing else is applied. There is no ageing treatment, no precipitation hardening step, and no stress relief inside the 1,000–600 °C band.

Soak time is counted from the moment the part itself reaches temperature, not from charging, and scales with the controlling section thickness d:

• d ≤ 10 mm: t = d × 3 min/mm
• d = 10 to 20 mm: t = 30 min + (d − 10) × 2 min/mm
• d > 20 mm: t = 50 min + (d − 20) × 1 min/mm

The 600–1,000 °C danger band

Hold a 6.5% molybdenum austenitic alloy anywhere between roughly 600 °C and 1,000 °C and it begins to precipitate sigma and chi phases at the grain boundaries. Kinetics are fastest near 850–900 °C, where measurable sigma can form in minutes. Two consequences follow. The precipitate is hard and brittle, so toughness falls. More importantly, sigma and chi are rich in chromium and molybdenum, so they draw those elements out of the adjacent matrix and leave a depleted zone that corrodes preferentially. The alloy still meets its certificate chemistry, but much of the corrosion resistance it was bought for has gone.

The practical consequence for heavy forgings is that the core is the controlling location, not the surface. A 300 mm thick block cannot be quenched at the core as fast as a 60 mm ring section, no matter how vigorous the tank. This is why we often propose splitting a heavy part, rolling it as a ring, or machining closer to net shape before the final anneal. All three reduce the controlling section so the quench can work.

NAS 325N vs Alloy 28, 254 SMO, AL-6XN, NAS 255NM, 625 and C-276

NAS 325N is among the most corrosion-resistant grades available in an iron-based stainless steel. Below it are the 6% molybdenum grades, which cost less but lack the chromium and copper for acid duty. Above it are the nickel-base alloys, which perform better in hydrochloric and hydrofluoric acid but cost several times as much.

N08031 compared with N08028

In the table above, Alloy 28 and NAS 325N carry the same chromium and nickel: 27% Cr, 31% Ni. Alloy 31 was developed from Alloy 28 by roughly doubling the molybdenum and adding nitrogen, in order to correct the weakness of Alloy 28 in chlorides. The two grades are therefore chemically adjacent, their Werkstoff numbers differ by one digit (1.4563 against 1.4562), and their names differ by one character.

This creates a practical problem at goods inward. An inspection that verifies 31% nickel and 27% chromium, and records the material as Alloy 31 on that basis, will pass Alloy 28. The PREN gap is 38 against 52, which in critical pitting temperature is roughly 45 °C against 85 °C. In seawater or wet-process phosphoric acid that difference determines service life.

When to step down, and when to step up

• Step down to NAS 255NM or 254 SMO when the duty is seawater or FGD without significant acid, and the temperature is well below the CPT. You lose acid capability you were not using, and save meaningfully on cost.
• Step down to 904L or Alloy 28 only when chlorides are low and sulfuric acid is the only problem. Both are cheaper; both pit at a fraction of the chloride level N08031 tolerates.
• Stay with NAS 325N whenever acid and chlorides appear together. Wet-process phosphoric acid is the main case, followed by contaminated sulfuric circuits and mixed-acid process streams.
• Step up to 654 SMO for hot concentrated brine or chloride duty above the N08031 CPT, where acid is not the driver.
• Step up to Alloy 59, C-276 or C-22 for hydrochloric acid, hydrofluoric acid, or strongly reducing conditions where molybdenum-rich nickel alloys are the only answer. Note that C-276 performs worse than NAS 325N in strongly oxidising acid such as boiling nitric, so a more expensive alloy is not automatically a better one.

How Do You Forge, Machine and Weld NAS 325N?

Forging

The hot-working window is 1,200 °C down to 1,050 °C (2,192–1,922 °F). Three points matter:

• Charge hot. Billets go into a furnace already at the top of the range rather than heating with the furnace, which minimises time spent in the precipitation band on the way up.
• Stop at 1,050 °C. Deformation below roughly 1,050 °C risks cracking and drives precipitation. Reheats are planned into the pass sequence, not treated as a recovery from a mistake.
• Cool fast after the last pass, in water or air depending on section, and then solution anneal properly. Forging heat is not a substitute for a solution treatment.

Expect higher press loads than for 304 or 316, because the alloy is stronger hot and work hardens faster, and expect more passes for the same reduction. Our 4,500 t press and the ring mills are sized accordingly.

Machining

Machine it as a high-nitrogen super austenitic rather than as an ordinary stainless steel. Use rigid setups and short tool overhangs, sharp tooling with positive rake, generous flood coolant, and lower surface speeds with heavier feeds so the cutting edge stays beneath the work-hardened layer. Dwelling and light finishing passes glaze the surface and destroy tools. Carbide grades intended for stainless work well. Expect roughly a third to a half of the metal removal rate you would plan for 316L.

Welding

NAS 325N is welded by GTAW, GMAW, SMAW and plasma processes. Matching filler is commercially available and is used where the weld sees the same duty as the base metal. However, molybdenum segregates to dendrite cores during solidification, leaving interdendritic regions depleted, so an as-welded matching deposit can be less corrosion resistant than the parent plate. Where weld corrosion resistance must equal or exceed the base metal, which is usual in acid and scrubber service, an over-alloyed nickel-base consumable such as Alloy 59 (ERNiCrMo-13) or ERNiCrMo-4 is specified instead.

No preheat is required. Keep heat input low and interpass temperature down, use argon backing on root runs, and remove heat tint by pickling and passivation afterwards. Heat tint is chromium-depleted oxide and becomes the first pitting site in service. Do not apply post-weld heat treatment unless a full solution anneal and quench is possible, because a conventional stress relief sits directly in the sigma-phase band.

Where Is NAS 325N Used?

NAS 325N Production Capability at Jiangyin Jiangnan Metal

Jiangyin Jiangnan Metal Co., Ltd. has forged open-die parts and seamless rolled rings since 2008 from its works in Zhouzhuang Town, Jiangyin, in the centre of China's flange and ring forging industry, and exports to more than 40 countries. Raw material, forging, heat treatment, machining, testing and inspection are organised on one site. That matters for this grade, because the quench rate determines the final properties and is not work to subcontract.

Standards, Testing and Certification

NAS 325N forgings are normally ordered to ASTM B564 / ASME SB-564. The specification sets the chemistry and mechanical minimums. The anneal, the quench, the corrosion testing and the surface condition all have to be written onto the purchase order separately.

What appears on the certificate

Quality gates and non-conformance handling

Three gates matter on this grade. Chemistry is verified on product analysis before forging release, rather than on the ladle sample alone. The solution anneal load is charted, and the chart is retained and issued with the certificate. Final NDT and dimensional inspection take place after the last heat treatment, never before, because a part annealed after ultrasonic inspection has not been inspected in its delivered condition. Where a non-conformance arises we report it before shipment with the proposed disposition, and concessions are not applied without the customer's agreement.

How to Specify a NAS 325N Forging Order

A specification that names only the grade leaves the remaining decisions to the supplier. The eight clauses below cover the points that most often cause problems on super austenitic forgings.

1. Name the grade generically. Write NAS 325N / UNS N08031 / EN 1.4562 rather than a trade name alone, so any qualified mill can supply the chemistry.
2. Separate it from Alloy 28 explicitly. State Mo 6.0–7.0%, N 0.15–0.25%. UNS N08028 / 1.4563 not acceptable.
3. Specify the delivery condition. Solution annealed 1,150–1,180 °C followed by rapid water quench. No ageing. No stress relief. No slow cooling through 1,000–600 °C at any stage of manufacture. Solution anneal time–temperature chart to accompany the certificate.
4. Set a minimum PREN and state the formula. PREN ≥ 50 calculated as Cr + 3.3Mo + 16N from product analysis. Without the formula the number is ambiguous.
5. Add corrosion testing where service demands it. ASTM G48 Method A for chloride duty; ASTM A262 Practice B or E, or ASTM G28, for intergranular attack.
6. State the ultrasonic acceptance class. Reference EN 10228-3, SEP 1921 or ASTM A388 and name the class. "UT required" with no criterion cannot be priced or enforced.
7. Control the surface condition. Pickled and passivated, free of heat tint, embedded iron and chloride-bearing marking inks.
8. Choose the certificate level. EN 10204 3.1 for the manufacturer's own independent inspection; 3.2 where a third party nominated by the purchaser must countersign.

Recommended drawing callout

MATERIAL: NAS 325N / UNS N08031 / EN 1.4562 (X1NiCrMoCu32-28-7)
FORGED PER ASTM B564 / ASME SB-564
Mo 6.0–7.0%, N 0.15–0.25% REQUIRED. UNS N08028 / 1.4563 NOT ACCEPTABLE.
CONDITION: SOLUTION ANNEALED 1150–1180 °C, RAPID WATER QUENCH
NO AGEING. NO STRESS RELIEF. ANNEAL CHART WITH CERTIFICATE.
PREN ≥ 50 (Cr + 3.3Mo + 16N) FROM PRODUCT ANALYSIS
CERT: EN 10204 3.1

Top 10 Mistakes When Ordering NAS 325N Forgings

1. Accepting Alloy 28 against an Alloy 31 order. Identical Ni and Cr, half the molybdenum, Werkstoff numbers one digit apart. Verify molybdenum on product analysis, every time.
2. Leaving the delivery condition unstated. "Heat treated" is not a specification. Name the temperature, the quench medium and the prohibition on stress relief.
3. Allowing a stress relief after machining. A conventional stress relief cycle sits in the middle of the sigma-phase band and quietly destroys the corrosion resistance.
4. Accepting ladle analysis only. Product analysis is what the delivered part actually contains. Ask for it.
5. Specifying a minimum PREN without the formula. The 16N and 30N conventions differ by more than a point on this grade.
6. Ordering a heavy solid block where a rolled ring would do. A thicker controlling section makes the quench harder, raises the sigma risk and costs more.
7. Writing "UT required" with no acceptance class. It cannot be priced at quotation and cannot be enforced in a dispute.
8. Ignoring surface condition. Heat tint left on the part is chromium-depleted oxide and becomes the first pitting site, regardless of how good the certificate looks.
9. Choosing on PREN alone in acid service. PREN barely reflects the copper and high chromium that make this grade work in sulfuric and phosphoric acid.
10. Assuming a more expensive alloy is always better. C-276 costs far more than N08031 and performs worse in boiling nitric acid. Match the alloy to the medium rather than to the price list.

Glossary

NAS 325N

Nippon Yakin Kogyo's designation for the super austenitic stainless steel registered as UNS N08031 and standardised in Europe as EN 1.4562. Nominally 31% Ni, 27% Cr, 6.5% Mo, 1.2% Cu, 0.2% N, balance iron.

Alloy 31

The common generic industry name for the same UNS N08031 chemistry. Also sold as Nicrofer 3127 hMo and ATI 31.

Alloy 28

UNS N08028 / W.Nr. 1.4563. A related grade with almost identical nickel and chromium to Alloy 31 but only 3–4% molybdenum and no deliberate nitrogen, giving a PREN of roughly 38. It is a frequent substitution error on N08031 orders.

Super austenitic stainless steel

A fully austenitic stainless steel with roughly 6% or more molybdenum and a deliberate nitrogen addition, giving a PREN above 40. The class sits between conventional austenitics such as 316L and nickel-base alloys such as alloy 625.

PREN

Pitting Resistance Equivalent Number, calculated as %Cr + 3.3 × %Mo + 16 × %N, or with 30 × %N in some producer literature. A ranking index for chloride pitting resistance, not a design limit.

CPT

Critical Pitting Temperature. The lowest temperature at which stable pitting occurs in a defined test solution, most commonly measured to ASTM G48 Method A in 6% ferric chloride. Approximately 85 °C for correctly annealed NAS 325N.

CCT

Critical Crevice Temperature. The equivalent threshold for crevice attack, typically 15–20 °C below the CPT of the same alloy. Crevices therefore govern real service more often than flat surfaces do.

Sigma phase

A hard, brittle Fe-Cr-Mo intermetallic that precipitates at grain boundaries when highly alloyed stainless steels are held between roughly 600 °C and 1,000 °C. It embrittles the alloy and strips molybdenum and chromium from the adjacent matrix, creating a depleted zone that corrodes preferentially.

Chi phase

A related Fe-Cr-Mo intermetallic, richer in molybdenum than sigma, that often precipitates first in high-molybdenum grades and has the same practical consequences.

Solution annealing

Heating an austenitic alloy high enough to dissolve carbides and intermetallic phases, 1,150–1,180 °C for NAS 325N, then quenching fast enough to hold everything in solid solution at room temperature. The only correct final heat treatment for this grade.

Wet-process phosphoric acid (WPA)

Phosphoric acid made by digesting phosphate rock in sulfuric acid, carrying fluorides, chlorides and abrasive solids alongside the acid. The application for which copper-bearing, high-chromium super austenitic grades were developed.

Erosion-corrosion

Accelerated material loss where a corrosive fluid carrying solids or moving at velocity continuously removes the passive film faster than it can reform. Common in WPA circuits and slurry duty.

Over-alloyed filler metal

A welding consumable richer in molybdenum and nickel than the parent metal, typically ERNiCrMo-13 (alloy 59) or ERNiCrMo-4 (C-276), used so the segregated as-welded deposit is still at least as corrosion resistant as the base material.

Heat tint

The coloured oxide left on stainless surfaces by welding or hot work. It is chromium-depleted and is a preferred pitting site, so it must be removed by pickling or mechanical removal followed by passivation, not simply brushed.

Chloride stress corrosion cracking (Cl-SCC)

Cracking of a stressed austenitic alloy in hot chloride solution. Susceptibility peaks around 8–12% nickel, which is why the 30–32% nickel of NAS 325N gives it a large margin over 304 and 316L.

ESR

Electroslag remelting. A secondary melting process that refines inclusion content and produces a directionally solidified ingot suited to forging segregation-prone chemistries.

AOD / VOD

Argon-oxygen decarburisation and vacuum-oxygen decarburisation. Secondary refining steps that bring carbon down to the 0.015% ceiling while holding nitrogen on aim.

EN 10204 3.1 / 3.2

Inspection document types. 3.1 is a mill certificate issued by the manufacturer's own independent inspection department; 3.2 is countersigned by an independent third party nominated by the purchaser.

Seamless rolled ring

A ring produced by piercing a forged billet and expanding it on a radial-axial ring mill, giving continuous circumferential grain flow and a thinner controlling section for the quench than a machined block.

Frequently Asked Questions: NAS 325N / UNS N08031

Technical References

Chemistry, corrosion, physical-property and heat-treatment data on this page are drawn from the published standards and producer datasheets below. Test results reported on our material certificates are independent and traceable to calibrated laboratory equipment.

1. ASTM B564, Standard Specification for Nickel Alloy Forgings, ASTM International, West Conshohocken, PA.
2. ASTM B649, Standard Specification for Ni-Fe-Cr-Mo-Cu-N Low-Carbon Alloys, and Ni-Cr-Mo-Cu Low-Carbon Alloys, Bar and Wire, ASTM International.
3. ASTM B581, Standard Specification for Nickel-Chromium-Iron-Molybdenum-Copper Alloy Rod, ASTM International.
4. ASTM B625, Standard Specification for UNS N08925, N08031, N08932, N08926 and related alloy Plate, Sheet and Strip, ASTM International.
5. ASTM B622, Standard Specification for Seamless Nickel and Nickel-Cobalt Alloy Pipe and Tube, ASTM International.
6. ASTM B366, Standard Specification for Factory-Made Wrought Nickel and Nickel Alloy Fittings, ASTM International.
7. EN 10204:2004, Metallic products — Types of inspection documents, CEN, Brussels.
8. EN 10228-3, Non-destructive testing of steel forgings — Part 3: Ultrasonic testing, CEN.
9. SEP 1921, Ultrasonic testing of steel forgings, Stahl-Eisen-Prüfblatt.
10. ASTM A388, Standard Practice for Ultrasonic Examination of Steel Forgings, ASTM International.
11. ASTM G48, Standard Test Methods for Pitting and Crevice Corrosion Resistance of Stainless Steels and Related Alloys by Use of Ferric Chloride Solution, ASTM International.
12. ASTM G31, Standard Guide for Laboratory Immersion Corrosion Testing of Metals, ASTM International.
13. ASTM A262, Standard Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels, ASTM International.
14. ASTM G28, Standard Test Methods for Detecting Susceptibility to Intergranular Corrosion in Wrought, Nickel-Rich, Chromium-Bearing Alloys, ASTM International.
15. NACE MR0175 / ISO 15156-3, Petroleum and natural gas industries — Materials for use in H₂S-containing environments in oil and gas production — Part 3: Cracking-resistant CRAs and other alloys.
16. ASME Boiler and Pressure Vessel Code, Section II Part B and Section VIII Division 1; ASME B31.3 Process Piping, The American Society of Mechanical Engineers.
17. VdTÜV-Werkstoffblatt 509 and SEW 400, material sheets covering the 1.4562 chemistry for pressure purposes.
18. Nippon Yakin Kogyo Co., Ltd., published product data for NAS 325N (UNS N08031).
19. ATI, Technical Data Sheet ATI 31™ Stainless Steel: Superaustenitic (UNS N08031). Source of the PREN, critical pitting temperature, immersion corrosion and ASME allowable stress figures quoted on this page.
20. VDM Metals International GmbH, VDM® Alloy 31 Nicrofer 3127 hMo Material Data Sheet No. 4131. Source of the hot-forming range and solution-annealing soak-time rule quoted on this page.
21. ASM Handbook, Volume 13B: Corrosion: Materials, ASM International, sections on austenitic and highly alloyed stainless steels.
22. Sedriks, A.J., Corrosion of Stainless Steels, 2nd edition, Wiley-Interscience. Standard reference for PREN, pitting and crevice behaviour.
23. ISO 9001:2015, Quality management systems — Requirements.

Standards cited are the revisions known to us at the time of the last page review. For procurement, always reference the revision in force at the contract date. Property values are typical or specified minimums published for the alloy and are provided for engineering guidance. They are not design allowables and do not replace the mill certificate for a specific order. All trademarks referenced belong to their respective owners.

Related Grades and Forged Products

• Alloy 31 / N08031
• NAS 255NM / N08926
• 254 SMO / S31254
• AL-6XN / N08367
• 904L / N08904
• 654 SMO / S32654
• Alloy 20 / N08020
• Incoloy 926
• Incoloy 825
• Inconel 625
• Alloy 59
• Hastelloy C-276
• Hastelloy C-22
• Hastelloy C-2000
• Forged & rolled rings
• Forged disks
• Forged tubes
• Forged spindles
• Forged nozzles
• Open die forgings