Alloy 31 Forgings, UNS N08031 / 1.4562

Open-die forged rings, seamless rolled rings, flanges, bars, discs, tube sheets and valve components in Alloy 31, solution annealed and water quenched, 10 kg to 15,000 kg.

Compiled by Jiangyin Jiangnan Metal Co., Ltd. from ASTM B564, ASTM B649, ASTM B625 and published mill data for UNS N08031. Confirm the governing revision on your order.

MaterialWhat is Alloy 31?

Alloy 31 is a super austenitic iron-nickel-chromium-molybdenum alloy with nitrogen and copper additions, standardised as UNS N08031 and W.Nr. 1.4562. The nitrogen content of 0.15 to 0.25% stabilises the austenite and slows sigma phase precipitation, so the alloy can carry 6 to 7% molybdenum and still be worked.

Buyers usually compare it against 6Mo grades such as 254 SMO and against nickel alloys such as Alloy 625. It handles acid better than the 6Mo grades and costs less than Alloy 625, which is why it turns up in specifications where a 6Mo grade has not lasted and Alloy 625 is too expensive.

Equivalent designations

ChemistryAlloy 31 chemical composition

Melting route: EAF, then AOD or VOD refining, then ESR where the order calls for electroslag remelted material. Carbon is held at 0.015% max and sulphur at 0.010% max because both drive intergranular attack in the acid service this alloy is bought for.

PropertiesMechanical and physical properties

Charpy V-notch impact testing, elevated temperature tensile testing and hardness mapping are run on request and reported on the EN 10204 certificate.

CorrosionWhy Alloy 31 gets specified

Most customers buy Alloy 31 for corrosion resistance rather than strength. Four figures usually decide the specification:

• Sulphuric acid: good resistance across a broad concentration range up to about 80 °C, including contaminated technical grade acid.
• Phosphoric acid: resists both corrosion and erosion corrosion in wet process acid carrying chlorides and fluorides.
• Pitting: critical pitting temperature of 85 °C in 10% FeCl₃·6H₂O, tested to ASTM G48 method A.
• Sensitisation: tested to ASTM G28 method A and SEP 1877 II, Alloy 31 only sensitises after long exposure, around 10 hours at 650 °C or 100 hours at 590 °C.

PREN compared with competing grades

PREN ranks pitting resistance in chloride media. It is not a guarantee of performance in a particular process stream, so check grade selection against your actual service conditions.

ManufacturingHow we forge and heat treat Alloy 31

Alloy 31 has a narrow hot working window and work hardens quickly. Of the whole route, the quench is the step that decides whether the customer gets the corrosion resistance they paid for.

1. Material. EAF plus AOD or VOD refined billet, ESR remelted where the specification requires it. Every heat is PMI checked before forging.
2. Forging. Worked from about 1,150 °C with the finishing temperature held above roughly 1,000 °C, reheated as needed. Open-die hammers of 1, 3, 6 and 9 tonnes, a 4,500 t hydraulic press, and 3 m and 6 m seamless ring rolling mills.
3. Solution annealing. 1,150 to 1,180 °C. Soak time follows section thickness: roughly 3 min per mm up to 10 mm, 30 min plus 2 min per mm from 10 to 20 mm, and 50 min plus 1 min per mm above 20 mm.
4. Quench. Water quench, straight out of the furnace. Air cooling a heavy Alloy 31 section precipitates sigma and chi phases at the grain boundaries and costs both corrosion resistance and toughness. Furnace charts go with the certificate.
5. Surface. Pickled and passivated to a clean, metallic bright condition. The alloy only reaches its rated corrosion resistance in that state.
6. Machining. Rough or finish machined to your drawing.

Product formsAlloy 31 forgings we supply

ApplicationsWhere Alloy 31 forgings are used

QualityTesting, inspection and certification

• Ultrasonic testing: 100% UT to ASTM A388, EN 10228-3 or SEP 1921, acceptance class to your order.
• Surface NDT: liquid penetrant to ASTM E165, magnetic particle where the geometry allows it.
• Corrosion testing: ASTM G28 method A for intergranular corrosion, ASTM G48 method A for pitting and CPT.
• Mechanical testing: tensile, hardness and Charpy V-notch impact on our own universal testing and impact machines.
• Metallurgy: metallographic microscope for grain size and intermetallic phase check, PMI on every heat.
• Certification: EN 10204 3.1 as standard, EN 10204 3.2 witnessed by TUV, BV or SGS on request.
• Approvals held: CCS, BV, DNV, LR and NK.

OrderingWhat we need to quote your Alloy 31 forging

Please include the following with your enquiry:

1. Drawing or finished dimensions, with the machining allowance you expect on the forging.
2. Quantity, and whether this is a one-off, a spare or a repeat order.
3. Governing standard, for example ASTM B564, ASTM B462 or ASTM B649.
4. Delivery condition and any restriction on melting route, such as ESR required.
5. NDT method and acceptance class, plus any corrosion test required.
6. Certificate type, EN 10204 3.1 or 3.2, and the third party if 3.2.
7. Sour service requirement, NACE MR0175 / ISO 15156, if it applies.
8. Destination port and required delivery date.

FAQFrequently asked questions

CompanyAbout Jiangyin Jiangnan Metal Co., Ltd.

Jiangyin Jiangnan Metal Co., Ltd. has been forging since 1997 in Jiangyin, Jiangsu Province, China. The company employs 460 people, including 9 senior engineers, 32 intermediate engineers and 140 technicians, and holds CCS, BV, DNV, LR and NK approvals. Forgings are exported to buyers in North America, Europe and Asia for petroleum and chemical processing, power generation, shipbuilding and heavy machinery.

Related nickel alloy forgings

• Alloy 59
• Incoloy 926
• Incoloy 825
• Inconel 625
• Hastelloy C-276
• Hastelloy C-22
• Incoloy 800H
• Inconel 718
• Monel 400
• Alloy 602

Published 6 June 2013. Last reviewed 12 August 2026 by the technical sales and metallurgy team, Jiangyin Jiangnan Metal Co., Ltd.