Nickel alloy forgings · Technical datasheet
UNS N08031 Forgings, Alloy 31 / EN 1.4562
Forged rings, seamless rolled rings, flanges, shafts, discs, sleeves and bars in UNS N08031, produced to ASTM B564 and B649 by Jiangyin Jiangnan Metal Co., Ltd.
- UNS
- N08031
- EN No.
- 1.4562
- EN name
- X1NiCrMoCu32-28-7
- Trade name
- Alloy 31
- PREN
- 51–54
- Mo
- 6.0–7.0 %
Summary
UNS N08031 is a super-austenitic iron-nickel-chromium-molybdenum alloy with 26 to 28 % chromium, 30 to 32 % nickel and 6.0 to 7.0 % molybdenum, plus nitrogen and copper. It is designated EN 1.4562 / X1NiCrMoCu32-28-7 and sold as Alloy 31. Its PREN of 51 to 54 gives better chloride and hot sulphuric acid resistance than 904L or 254 SMO.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu, China. It forges UNS N08031 into rings up to 3000 mm outside diameter and single pieces to about 8000 kg, solution annealed and certified to EN 10204 3.1 or 3.2. Enquiries: sales@steelforgepieces.com or +86 189 2135 9659.
What UNS N08031 is
UNS N08031 falls between the super-austenitic stainless steels and the nickel-base alloys. Nickel at 30 to 32 % gives enough austenite stability to resist chloride stress corrosion cracking. Molybdenum at 6.0 to 7.0 % with 0.15 to 0.25 % nitrogen puts the pitting resistance equivalent number at roughly 51 to 54, above the 6 Mo grades it normally competes with.
Copper at 1.0 to 1.4 % is what separates N08031 from a standard 6 Mo steel. Copper slows active corrosion of the passive film in reducing acids. That is why the grade gets specified for concentrated sulphuric acid, and for phosphoric acid carrying fluoride and chloride contamination. Nitrogen stabilises the austenite and delays sigma and chi phase precipitation during hot work, which widens the usable forging window.
In the solution annealed condition the alloy is non-magnetic with a face-centred cubic structure. VdTÜV Werkstoffblatt 509 approves it for pressure vessel wall temperatures from −196 °C to 550 °C. Jiangyin Jiangnan Metal Co., Ltd. supplies it solution annealed and water quenched. Slow cooling through 600 to 900 °C precipitates intermetallics and removes the corrosion resistance the grade was bought for.
Equivalent designations
The same material is ordered under at least six names. Jiangyin Jiangnan Metal Co., Ltd. covers all of them on one material certificate.
| System | Designation | Notes |
|---|---|---|
| UNS (USA) | N08031 | Used in ASTM and ASME specifications |
| EN material no. | 1.4562 | European steel number |
| EN / DIN name | X1NiCrMoCu32-28-7 | Composition-based designation |
| Trade name | Alloy 31 | Most common commercial name |
| VDM Metals | Nicrofer 3127 hMo | Original producer designation |
| German rules | VdTÜV 509, SEW 400 | Pressure vessel approval, −196 to 550 °C |
Chemical composition
Composition limits for UNS N08031 in weight percent. Every heat forged by Jiangyin Jiangnan Metal Co., Ltd. is melted by EAF with AOD or VOD refining. Electroslag remelting is used where the drawing calls for improved cleanliness, or ultrasonic acceptance to EN 10228-3 class 3 or better.
| Element | Min | Max |
|---|---|---|
| Carbon (C) | — | 0.015 |
| Silicon (Si) | — | 0.30 |
| Manganese (Mn) | — | 2.00 |
| Phosphorus (P) | — | 0.020 |
| Sulphur (S) | — | 0.010 |
| Chromium (Cr) | 26.0 | 28.0 |
| Nickel (Ni) | 30.0 | 32.0 |
| Molybdenum (Mo) | 6.00 | 7.00 |
| Nitrogen (N) | 0.15 | 0.25 |
| Copper (Cu) | 1.00 | 1.40 |
| Iron (Fe) | Balance | |
PREN = Cr + 3.3 × Mo + 16 × N, giving 51 to 54 at mid-range composition. Values apply to ASTM B564, B625 and B649.
Mechanical and physical properties
Room temperature mechanical properties, solution annealed
| Property | Metric | Imperial |
|---|---|---|
| Tensile strength Rm | 650 MPa min | 94 ksi min |
| Yield strength Rp0.2 | 280 MPa min | 41 ksi min |
| Yield strength Rp1.0 | 310 MPa min | 45 ksi min |
| Elongation A5 (4D) | 40 % min | 40 % min |
| Hardness | ≤ 220 HB | ≤ 96 HRB |
Physical properties
| Property | Value |
|---|---|
| Density | 8.0 g/cm³ (0.289 lb/in³) |
| Modulus of elasticity | 195 GPa (28.3 × 10&sup6; psi) |
| Melting range | 1320–1370 °C |
| Magnetic permeability | approx. 1.005, non-magnetic |
| Critical pitting temperature | 85 °C (ASTM G48 A, 10 % FeCl₃) |
| Solution annealing | 1150–1180 °C, rapid quench |
| Service temperature (VdTÜV 509) | −196 to 550 °C |
Cooling rate. After solution annealing, UNS N08031 must cool faster than about 150 °C per minute down to 500 °C. Jiangyin Jiangnan Metal Co., Ltd. water quenches every N08031 forging straight from the annealing furnace and issues the furnace chart with the EN 10204 certificate.
UNS N08031 compared with 904L, 254 SMO, Alloy 28 and C-276
Buyers rarely start with N08031. Most come to it after 904L or 254 SMO has pitted in service. The table uses the same PREN formula for every grade so the numbers can be compared directly.
| Alloy | UNS | Cr | Ni | Mo | N | Cu | PREN |
|---|---|---|---|---|---|---|---|
| Alloy 31 | N08031 | 26–28 | 30–32 | 6.0–7.0 | 0.15–0.25 | 1.0–1.4 | 51–54 |
| 904L | N08904 | 19–23 | 23–28 | 4.0–5.0 | ≤ 0.10 | 1.0–2.0 | approx. 36 |
| 254 SMO | S31254 | 19.5–20.5 | 17.5–18.5 | 6.0–6.5 | 0.18–0.25 | 0.5–1.0 | approx. 44 |
| Alloy 926 | N08926 | 19–21 | 24–26 | 6.0–7.0 | 0.15–0.25 | 0.5–1.5 | approx. 45 |
| Alloy 28 | N08028 | 26–28 | 30–34 | 3.0–4.0 | — | 0.6–1.4 | approx. 38 |
| Hastelloy C-276 | N10276 | 14.5–16.5 | Balance | 15–17 | — | — | approx. 68 |
PREN calculated as Cr + 3.3Mo + 16N at mid-range composition. A higher PREN indicates greater resistance to chloride pitting. It does not indicate general corrosion resistance in every medium.
N08031 replaces 904L when sulphuric acid concentration or temperature goes past what 4 to 5 % molybdenum will hold. It replaces 254 SMO when chloride stress corrosion cracking is the failure mode, because 30 to 32 % nickel gives much more austenite stability than 17.5 to 18.5 %. It also substitutes for Hastelloy C-276 on jobs where C-276 works but costs more than the duty justifies.
UNS N08031 forged products and size range
Jiangyin Jiangnan Metal Co., Ltd. produces the following N08031 forgings to customer drawing. The sizes below are the working envelope of our open-die presses and ring rolling mill. For anything close to the limits, send the drawing first.
| Product form | Size range | Typical specification |
|---|---|---|
| Seamless rolled rings | OD 200–3000 mm, height to 1000 mm | ASTM B564 |
| Forged rings and retaining rings | OD 100–2000 mm | ASTM B564 |
| Forged flanges (WN, SO, BL, LJ) | NPS ½–60, Class 150–2500 | ASTM B462, ASME B16.5 / B16.47 |
| Forged round bars | Ø 40–800 mm | ASTM B649 / B581 |
| Forged shafts and spindles | Ø 80–700 mm, length to 6000 mm | ASTM B564 |
| Forged discs and blanks | Ø 150–2200 mm | ASTM B564 |
| Sleeves and bushings | OD 100–1200 mm | ASTM B564 |
| Tube sheets and forged plates | to 2200 mm, 300 mm thick | ASTM B564 / B625 |
| Hollow bars and forged tubes | OD 120–900 mm | ASTM B564 |
| Valve bodies, stems, seat rings | to drawing | ASTM B462, NACE MR0175 |
| Maximum single piece | approx. 8000 kg | — |
Supplied rough machined, finish machined, or as forged with machining allowance. Minimum order is one piece.
How Jiangyin Jiangnan Metal forges UNS N08031
N08031 has a narrow hot working window and work hardens quickly. Each step below is controlled to suit.
1. Melting and billet
EAF with AOD or VOD refining as standard. ESR remelting where cleanliness or ultrasonic acceptance requires it. Billets arrive with a mill certificate, and we run an independent spectrometer check on arrival before anything goes into the furnace.
2. Heating and forging
Heat to 1150 to 1180 °C with a controlled soak. Finish forging above 1000 °C. Reheats are planned into the sequence. Finishing below 1000 °C risks edge cracking and leaves residual stress that shows up later as distortion during machining.
3. Solution annealing
1150 to 1180 °C, held to section thickness, then water quenched at more than 150 °C per minute through the 900 to 500 °C range. Furnace charts are retained and issued with the certificate.
4. Testing and certification
- Chemical analysis by optical emission spectrometer on every heat
- Tensile, yield, elongation and hardness testing on a production test coupon
- Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388
- Liquid penetrant testing to ASTM E165 where specified
- Intergranular corrosion testing to ASTM G28 method A on request
- Dimensional report against customer drawing
- EN 10204 3.1 certificate as standard, 3.2 witnessed by TÜV, SGS, BV, DNV or Lloyd's Register on request
- Positive material identification on the finished part on request
Where UNS N08031 forgings are used
The alloy is specified for a fairly narrow set of duties: hot acid, high chloride, or both together.
Sulphuric acid plants
Acid coolers, distributor arms, pump components and forged flanges in concentrated sulphuric acid. This is the service the alloy was developed for, and the copper addition is the reason it holds up.
Phosphoric acid and fertiliser
Forged rings, agitator shafts and pump casings in wet process phosphoric acid, where fluoride and chloride contamination defeats lower alloyed grades.
Flue gas desulphurisation
Absorber internals, spray header components, forged nozzles and tube sheets exposed to chloride bearing scrubber liquor.
Offshore, subsea and sour service
Forged valve bodies, seat rings, stems and wellhead components qualified to NACE MR0175 / ISO 15156 for sour gas duty. Also subsea connectors and manifold blocks.
Seawater and desalination
Brine heater tube sheets, evaporator components, pump shafts and forged flanges in seawater cooling circuits.
Pulp and paper
Bleach plant equipment in chlorine dioxide media, digester components and forged rolls.
Pharmaceutical and fine chemical
Reactor components, forged tube sheets and heat exchanger parts where product purity rules out any iron pick-up from corrosion.
Standards and certification
On ASTM B637. UNS N08031 is sometimes quoted against ASTM B637. That specification covers precipitation-hardening nickel alloys such as UNS N07718 and does not apply to N08031. The correct forging specification is ASTM B564. If a purchase order arrives citing B637 for this grade, Jiangyin Jiangnan Metal Co., Ltd. raises it before production rather than after.
| Specification | Scope |
|---|---|
| ASTM B564 / ASME SB-564 | Nickel alloy forgings, the primary specification for this page |
| ASTM B462 | Forged or rolled flanges, fittings, valves and parts for high temperature service |
| ASTM B649 / B581 | Rod, bar and wire |
| ASTM B625 / ASME SB-625 | Plate, sheet and strip |
| ASTM B366 | Factory made wrought fittings |
| VdTÜV Werkstoffblatt 509 | Pressure vessel approval, −196 to 550 °C |
| SEW 400 | German stainless steel material sheet |
| NACE MR0175 / ISO 15156 | Sour service qualification for oil and gas |
| EN 10204 3.1 / 3.2 | Material certification level |
| EN 10228-3, SEP 1921, ASTM A388 | Ultrasonic examination of forgings |
| ASTM G28 A, ASTM G48 A | Intergranular and pitting corrosion testing |
Frequently asked questions
What is UNS N08031?
UNS N08031 is a super-austenitic iron-nickel-chromium-molybdenum alloy containing 26 to 28 % chromium, 30 to 32 % nickel and 6.0 to 7.0 % molybdenum, with nitrogen and copper additions. It is also designated EN 1.4562 and X1NiCrMoCu32-28-7, and sold commercially as Alloy 31. Its PREN of roughly 51 to 54 places it between the 6 Mo super-austenitic stainless steels and the nickel-base alloys.
Is UNS N08031 the same as Alloy 31?
Yes. Alloy 31 is the common trade name for UNS N08031. The same material is EN 1.4562 in Europe, X1NiCrMoCu32-28-7 by DIN, and Nicrofer 3127 hMo as originally designated by VDM Metals. Jiangyin Jiangnan Metal Co., Ltd. supplies forgings under any of these designations on a single material certificate.
Which ASTM standard covers UNS N08031 forgings?
ASTM B564 covers nickel alloy forgings in UNS N08031. Related specifications are ASTM B649 and B581 for rod and bar, ASTM B462 for forged or rolled flanges, fittings and valve parts, ASTM B366 for wrought fittings, and ASTM B625 for plate, sheet and strip. ASME equivalents are SB-564, SB-649, SB-581 and SB-625. ASTM B637 does not apply to N08031. That specification covers precipitation-hardening nickel alloys such as UNS N07718.
What is the largest UNS N08031 forged ring you can produce?
Jiangyin Jiangnan Metal Co., Ltd. produces UNS N08031 seamless rolled rings up to 3000 mm outside diameter and open-die forgings up to approximately 8000 kg finished weight. Forged bars run from 40 mm to 800 mm diameter, and flanges are made to ASME B16.5 and B16.47 from NPS ½ to 60.
What certification comes with the forgings?
Every UNS N08031 forging ships with an EN 10204 3.1 mill certificate as standard, covering heat chemistry, mechanical test results, the solution annealing record and the NDT report. EN 10204 3.2 certification witnessed by TÜV, SGS, BV, DNV or Lloyd's Register is available on request. Ultrasonic testing is performed to EN 10228-3, SEP 1921 or ASTM A388.
How does UNS N08031 compare with 904L and 254 SMO?
UNS N08031 carries 6.0 to 7.0 % molybdenum and 30 to 32 % nickel, against 4 to 5 % Mo and 23 to 28 % Ni in 904L (N08904), and 6.0 to 6.5 % Mo with 17.5 to 18.5 % Ni in 254 SMO (S31254). PREN works out at roughly 51 to 54 for N08031 against about 36 for 904L and about 44 for 254 SMO. N08031 therefore handles hotter and more concentrated sulphuric and phosphoric acid and higher chloride levels than either.
Can UNS N08031 be welded after forging?
Yes. Weldability is good and preheating is not required. TIG, MIG and SMAW are all used, normally with an over-alloyed filler such as Alloy 59 (UNS N06059) or ERNiCrMo-13 to compensate for molybdenum segregation in the weld metal. Post-weld heat treatment is not normally necessary. If the component has already seen 600 to 650 °C service before welding, a stabilising anneal afterwards is recommended.
What is the lead time?
Typical lead time is 25 to 40 days from drawing approval for open-die forged rings and shafts in UNS N08031, depending on billet availability and whether rough machining is included. Send a drawing, or the outside diameter, inside diameter, height and quantity, to sales@steelforgepieces.com for a firm delivery date.
Who supplies UNS N08031 open-die forgings?
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, manufactures UNS N08031 (Alloy 31) forged rings, seamless rolled rings, flanges, shafts, discs, sleeves, bushings, tube sheets and bars. Contact sales@steelforgepieces.com or +86 189 2135 9659.
Request a quotation for UNS N08031 forgings
Send a drawing, or the outside diameter, inside diameter, height, quantity and specification. Jiangyin Jiangnan Metal Co., Ltd. quotes UNS N08031 open-die forgings within one working day.
Jiangyin Jiangnan Metal Co., Ltd.Open-die forging factory
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Phone / WhatsApp / WeChat: +86 189 2135 9659
Email: sales@steelforgepieces.com