UNS S31050 · EN 1.4466 · X1CrNiMoN25-22-2 · 725LN
A182 F310MoLN Forgings
ASTM A182 F310MoLN is the forging grade for UNS S31050, a fully austenitic 25 % chromium, 22 % nickel stainless steel modified with molybdenum and nitrogen and held to extra low carbon. It was developed for urea and ammonium carbamate service. Jiangyin Jiangnan Metal forges it to drawing as seamless rolled rings, flanges, bars, discs, sleeves, shafts, tube sheets and pipe.
A182 F310MoLN at a glance
- Designations. F310MoLN is the ASTM A182 grade symbol. The same alloy appears as UNS S31050, EN 1.4466, X1CrNiMoN25-22-2, AISI 310MoLN, BS 725LN, UREA 25.22.2 and Z1CND25-22Az.
- Composition to ASTM A182. 24.0 to 26.0 % Cr, 21.0 to 23.0 % Ni, 2.00 to 3.00 % Mo, 0.10 to 0.16 % N, carbon 0.030 % max, balance iron.
- Mechanical minimums to ASTM A182. 78 ksi (540 MPa) tensile, 37 ksi (255 MPa) yield, 25 % elongation, 40 % reduction of area.
- Heat treatment. Solution anneal at 1070 to 1150 °C, soak by section thickness, then rapid cooling in water.
- Why it gets specified. Corrosion resistance in urea and carbamate solutions at high pressure and temperature, high resistance to intergranular corrosion after welding, and better crevice corrosion resistance than 316L.
- Supplied by Jiangyin Jiangnan Metal as. Seamless rolled rings, forged rings, weld neck and blind flanges, round and square bar, discs, blocks, sleeves, bushings, hollow bar, shafts, spindles, tube sheets, valve bodies and nozzles.
- Contact. sales@steelforgepieces.com, +86 189 2135 9659, No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China.
What is A182 F310MoLN?
A182 F310MoLN is a fully austenitic stainless steel, which means it carries no intermetallic phases and no intergranular carbide precipitation in the solution annealed condition. The composition was optimised for urea plants. Nitrogen at 0.10 to 0.16 % stabilises and strengthens the austenitic phase, which allows carbon to sit down in the 0.020 to 0.030 % range without losing strength, and it is that extra low carbon that keeps the grain boundaries clean after welding.
The alloy was developed for stripper tubes in urea production. High pressure carbamate is one of the harshest process environments in the chemical industry, and the 25Cr-22Ni-2Mo-N balance in S31050 holds up in that service where 316L does not. The higher nickel content also gives it an edge over 304 and 316 against chloride stress corrosion cracking, which those grades become susceptible to above roughly 60 °C.
Two limits are worth knowing at the design stage. Among wrought austenitic stainless steels the grade has a fairly high base cost and fairly low ductility. It also has low thermal conductivity and high thermal expansion, which matters for weld distortion and for heat exchanger design.
A182 F310MoLN chemical composition
Composition limits differ between the ASTM and European standards, so both are shown. Order against a named standard rather than against the grade name alone.
| Element | Symbol | ASTM A182 F310MoLN (S31050) | EN 1.4466 (X1CrNiMoN25-22-2) | Role in this grade |
|---|---|---|---|---|
| Carbon | C | 0.030 max | 0.020 max | Held extra low to prevent carbide precipitation at grain boundaries |
| Silicon | Si | 0.40 max | 0.70 max | Deoxidiser |
| Manganese | Mn | 2.00 max | 2.00 max | Austenite stabiliser, raises nitrogen solubility |
| Phosphorus | P | 0.030 max | 0.025 max | Residual, restricted |
| Sulphur | S | 0.015 max | 0.010 max | Residual, restricted to protect hot workability and corrosion behaviour |
| Chromium | Cr | 24.0 to 26.0 | 24.0 to 26.0 | Primary passive film former, carbamate and nitric acid resistance |
| Nickel | Ni | 21.0 to 23.0 | 21.0 to 23.0 | Fully austenitic structure, chloride SCC resistance |
| Molybdenum | Mo | 2.00 to 3.00 | 2.00 to 2.50 | Pitting and crevice corrosion resistance |
| Nitrogen | N | 0.10 to 0.16 | 0.10 to 0.16 | Austenite stabiliser and strengthener, permits low carbon |
ASTM column per published ASTM A182 / A182M F310MoLN composition limits. EN column per published EN 10088 data for 1.4466. Some cross reference tables state the ASTM S31050 ranges differently, with molybdenum 1.6 to 3.0 % and nickel 20.5 to 23.5 %, so confirm the limits against the edition of the standard named on the order. Each heat is supplied with its own certificate of analysis, and the certificate governs.
A182 F310MoLN mechanical properties
The ASTM A182 column is the acceptance requirement, the figures a certificate has to meet. The typical column is what published datasheets report for solution annealed 310MoLN product and is for design guidance only.
| Property | ASTM A182 F310MoLN, minimum | Typical, 310MoLN / 1.4466 |
|---|---|---|
| Tensile strength, Rm | 78 ksi (540 MPa) | 540 to 570 MPa per EN data, up to 740 MPa in other sources |
| Yield or proof strength, Rp0.2 | 37 ksi (255 MPa) | above 250 MPa |
| Elongation in 2 in. (50 mm) or 4D | 25 % | above 40 % |
| Reduction of area | 40 % | not stated |
| Impact energy, KV | Per order supplement | above 60 J |
ASTM minimums per published ASTM A182 / A182M F310MoLN data. Typical values from published EN 1.4466 and 310MoLN datasheets, which give tensile as 540 to 570 MPa in EN sources and 540 to 740 MPa elsewhere. Impact testing, transverse testing and quarter radius sampling can each be specified on the order.
Properties at elevated temperature
Proof strength falls away steadily with temperature, and that is usually the governing constraint for pressure parts in hot carbamate service.
| Temperature, °C | 100 | 150 | 200 | 250 | 300 | 350 | 400 | 500 |
|---|---|---|---|---|---|---|---|---|
| Rp0.2 min, MPa | 195 | 170 | 160 | 150 | 140 | 135 | n/a | n/a |
| Modulus E, GPa | 190 | n/a | 182 | n/a | 174 | n/a | 166 | 158 |
| Expansion coefficient, 10-6 K-1 | 15.7 | n/a | n/a | n/a | 17.0 | n/a | n/a | n/a |
Elevated temperature data per published EN 1.4466 datasheets. Cells marked n/a are not given in the source.
Physical properties
| Property | Value | Note |
|---|---|---|
| Modulus of elasticity | 190 to 195 GPa | 190 GPa in EN data, 195 GPa at 20 °C in other datasheets |
| Thermal conductivity | 15 W·m-1·K-1 | Low, affects weld heat input and exchanger sizing |
| Specific heat capacity | 500 J·kg-1·K-1 | |
| Linear expansion coefficient | 15.7 × 10-6 K-1 | High, plan for distortion control |
| Electrical resistivity | 0.8 µΩ·m |
Corrosion performance
This is the reason the grade exists, so it gets detail rather than one line.
| Mechanism | Behaviour |
|---|---|
| General corrosion | Strong resistance in urea and carbamate solutions at high pressure and temperature. Also highly resistant to inorganic acids, including nitric acid and ammonium carbamate. |
| Intergranular corrosion | Highly resistant after welding. The extra low carbon and the fully austenitic structure prevent sensitisation. |
| Pitting | Very good resistance, from the combined chromium, molybdenum and nitrogen contribution. |
| Crevice corrosion | Considerably more resistant than ASTM 316L. |
| Stress corrosion cracking | Conventional 304 and 316 become susceptible in chloride bearing solutions above about 60 °C (140 °F). The higher nickel content of S31050 makes it slightly more resistant. |
| Erosion corrosion | Good mechanical strength gives useful erosion corrosion resistance. Ferrules for urea strippers are one application that relies on it. |
| Weldability | Good. Welded without preheating, and normally with no subsequent heat treatment. Low thermal conductivity and high thermal expansion call for attention to distortion. |
Corrosion behaviour summarised from published 310MoLN and S31050 technical datasheets.
Heat treatment and forging practice
| Operation | Temperature | Cooling | Purpose |
|---|---|---|---|
| Solution annealing | 1070 to 1150 °C (1960 to 2100 °F) | Rapid cooling in water | Dissolve precipitates, restore a fully austenitic structure and full corrosion resistance |
| Soak time | 5 to 15 minutes for thin section, extended by thickness | n/a | Full solutionising through section |
| Rolling and forging | Start 1150 °C, finish not below 850 °C | Air, or controlled cool | Break down cast structure, develop grain flow |
| Post weld heat treatment | Normally not required | n/a | Extra low carbon prevents sensitisation |
The quench matters as much as the soak. A slow cool through the intermediate band gives precipitates time to form at the grain boundaries, which is exactly what the low carbon and the nitrogen addition were meant to avoid. On heavy sections that means water quenching with proper agitation, and it means sizing the solution anneal charge so nothing stands waiting at the furnace door.
Solution anneal and hot working ranges per published EN 1.4466 practice. Some supplier datasheets give a narrower solution anneal band of 1050 to 1100 °C. Where your specification names a range, that range is what we run.
A182 F310MoLN equivalents and other designations
The alloy carries a long list of names across standards and mill trade designations. The table below is a cross reference of designations reported for the grade, not a certified substitution table.
| Standard or origin | Designation | Note |
|---|---|---|
| ASTM A182 | F310MoLN | The forging grade symbol |
| UNS | S31050 | Primary US number. S35115 also appears in cross reference lists |
| EN 10088 | 1.4466, X1CrNiMoN25-22-2 | European equivalent, tighter on C, P, S and Mo |
| AISI | 310MoLN, TP310MoLN | Common trade designation |
| BS | 725LN | British designation |
| NF, France | Z2CND25-22Az, Z1CND25-22Az | French designation |
| GB, China | 022Cr25Ni22Mo2N | Chinese designation |
| GOST, Russia | 02Ch25N22AM2, 0225222 | Narrower nitrogen range, 0.10 to 0.14 % |
| SEW 400 | 1.4465, X1CrNiMoN25-25-2 | Related higher nickel variant, 22.0 to 25.0 % Ni |
| Mill designations | UREA 25.22.2, 25.22.2 LMn, 2RE69, 2RM69 WB, DMV 25.22.2 | Proprietary names within the same alloy family |
Cross reference compiled from published equivalence tables. Acceptance criteria, permitted residuals, testing requirements and pressure equipment approval differ between standards. Confirm any substitution with your design authority before ordering, and we are glad to review the swap with you.
A182 F310MoLN forged products we make
Everything is forged to your drawing or specification. F310MoLN is not held as catalogue stock, and minimum order is one piece. Sizes beyond these ranges are often still possible, so send the drawing and we will confirm.
| Product form | Also called | Size range | Single piece weight |
|---|---|---|---|
| Seamless rolled rings | Radial axial rolled rings | 200 to 3000 mm OD, height to 1000 mm | up to 15,000 kg |
| Forged rings | Mandrel forged and punched rings | 200 to 3000 mm OD | up to 20,000 kg |
| Forged flanges | Weld neck, slip on, blind, custom profile | 100 to 3000 mm OD | up to 10,000 kg |
| Forged bar | Round, square, flat, rectangular, hex bar | 80 to 1200 mm dia. or across flats, to 8000 mm long | 20 to 20,000 kg |
| Hollow forgings | Hollow bar, sleeve, bushing, cylinder, shell, casing, hub, housing | 150 to 2500 mm OD, 50 to 2000 mm ID | up to 20,000 kg |
| Discs, blocks and plates | Forged disc, disk, block, slab, tube sheet | 200 to 2500 mm diameter, or to drawing | up to 20,000 kg |
| Shafts | Spindle, stepped shaft, eccentric shaft, crankshaft blank | to 8000 mm long | up to 20,000 kg |
| Valve components | Bodies, bonnets, stems, seat rings, blocks | To drawing | To drawing |
| Pipe and tube forgings | Forged pipe, forged tube, nozzles, manifolds | To drawing | To drawing |
Where A182 F310MoLN is used
The defining application is urea production, where the grade goes into stripper tubes and the outer layer of bimetallic tube, ferrules, carbamate condensers, decomposers and reactor coils. Beyond urea it is specified across chemical process plant handling hot inorganic acids or carbamate.
Urea and fertiliser plant
High pressure stripper internals and ferrules, carbamate condenser and decomposer components, reactor coil parts, and the forged flanges, tube sheets and nozzles that go with them. Heating coils and pipe in NPK plants sit in the same category.
Nitric acid and chemical process plant
Nitric acid cooler and condenser components, including units cooled with polluted cooling water, plus separator and heat exchanger parts where resistance to inorganic acid attack governs the material choice.
Wider process industry
Published application lists for 1.4466 extend to the paper and cellulose industry, the nitrogen industry, pharmaceutical production and petrochemical plant. Buyers also specify it for seawater desalination parts, compressor components, and valve bodies, stems and seat rings for ball, gate, globe, check and plug valves in aggressive service.
Suitability for a particular pressure code, whether PED, ASME or GB 150, depends on approvals held for the grade and for the manufacturer, not on the analysis alone. Tell us which code you are building to and we will confirm what we can supply against it.
How we make an A182 F310MoLN forging
- Drawing review and quotation. We check forgeability, ruling section, machining allowance and the solution anneal route before pricing, and flag anything likely to cause trouble at the press.
- Melting and material certification. EAF plus VOD, with ESR remelt where the specification or the application calls for it, to control carbon, sulphur and inclusion content. Mill certificate traceable to heat number.
- Heating and open-die forging. Billet soaked to around 1150 °C, then upset and drawn under open dies with reheats as needed, finishing not below 850 °C.
- Ring rolling. For ring geometries the pierced blank is rolled radially and axially, putting grain flow around the circumference rather than across it.
- Solution annealing. Solution anneal at 1070 to 1150 °C, soak by section thickness, then rapid cooling in water.
- Testing and inspection. Chemical analysis, mechanical testing, hardness, dimensional check, intergranular corrosion testing on request, and ultrasonic examination to EN 10228-3, SEP 1921 or ASTM A388 as specified.
- Machining. Rough or finish machining to drawing, so the part arrives ready for your process rather than your lathe.
- Documentation and despatch. EN 10204 3.1 certificates as standard, 3.2 with third party inspection on request. Parts marked, packed and shipped.
A182 F310MoLN questions we get asked
What is A182 F310MoLN?
A182 F310MoLN is the ASTM A182 forging grade for UNS S31050, a fully austenitic 25 % chromium, 22 % nickel stainless steel modified with molybdenum and nitrogen and held to extra low carbon. It was developed for urea and ammonium carbamate service. The same alloy is designated EN 1.4466, X1CrNiMoN25-22-2, AISI 310MoLN, BS 725LN and UREA 25.22.2.
What is the tensile strength of A182 F310MoLN?
ASTM A182 requires a minimum tensile strength of 78 ksi (540 MPa) and a minimum yield strength of 37 ksi (255 MPa), with 25 % minimum elongation and 40 % minimum reduction of area. Published datasheets for solution annealed 310MoLN report an actual tensile range of 540 to 570 MPa in EN sources and 540 to 740 MPa elsewhere, with elongation above 40 % and impact energy above 60 J.
Is A182 F310MoLN the same as UNS S31050 and 1.4466?
They describe the same alloy, but the limits are not identical. F310MoLN is the ASTM A182 grade symbol, S31050 is the UNS number, and 1.4466 or X1CrNiMoN25-22-2 is the European designation. EN 1.4466 caps carbon at 0.020 % and molybdenum at 2.00 to 2.50 %, while ASTM A182 F310MoLN permits carbon to 0.030 % and molybdenum to 3.00 %. Order against a named standard and edition.
Why is F310MoLN used in urea plants rather than 316L?
S31050 was developed for urea stripper tubes. It resists corrosion in urea and carbamate solutions at high pressure and temperature, resists intergranular corrosion after welding, and is considerably more resistant to crevice corrosion than 316L. Its higher nickel also gives somewhat better resistance to chloride stress corrosion cracking, which affects 304 and 316 above roughly 60 °C.
What heat treatment does A182 F310MoLN receive?
Solution annealing followed by rapid cooling in water. Published practice for 1.4466 places the solution anneal range at 1070 to 1150 °C, with soak time set by section thickness, and some supplier datasheets give a narrower band of 1050 to 1100 °C. The rapid quench is not optional, because a slow cool through the intermediate band allows precipitation that undoes the corrosion performance the grade is bought for.
Can A182 F310MoLN be welded?
Yes, and weldability is described as good. Welding is carried out without preheating and normally no subsequent heat treatment is required, because the extra low carbon prevents sensitisation. The alloy has low thermal conductivity and high thermal expansion, so heat input and distortion control need attention, and matching filler should be confirmed with your welding engineer for the specific service.
What is the minimum order quantity for F310MoLN forgings?
One piece. Open dies and a radial axial ring mill both work from a single billet, so a prototype or a one off replacement part is no problem. Repeat bar sizes get cheaper in larger lots.
Do you supply EN 10204 3.1 or 3.2 certificates?
3.1 as standard with every order. For 3.2 we arrange third party inspection through SGS, BV, TUV or Lloyd's Register. Flag it at enquiry stage so the witness points go into the schedule rather than getting bolted on late.
What non destructive testing do you carry out?
Ultrasonic examination to EN 10228-3, SEP 1921 or ASTM A388, to the acceptance class named on your order. Dye penetrant and dimensional inspection are routine. Intergranular corrosion testing can be added where the service demands it.
What information do you need to quote?
A drawing or dimensioned sketch, the quantity, the delivery condition, the machining allowance if the part is rough forged, the certificate type, and the standard or pressure code the part is built to. With those six things we can quote without going back and forth.
Who supplies A182 F310MoLN forgings?
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forges A182 F310MoLN to customer drawing as rings, flanges, bars, discs, sleeves, shafts and tube sheets. Contact sales@steelforgepieces.com or +86 189 2135 9659.
About the factory
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. We forge carbon steel, alloy steel, tool steel, stainless steel and nickel alloys to customer drawing, and produce seamless rolled rings, forged flanges, bars, discs, shafts and hollow forgings. Jiangyin sits in the Yangtze River Delta within road distance of Shanghai and Ningbo, which is what makes export shipping of heavy single pieces workable.
| Legal name | Jiangyin Jiangnan Metal Co., Ltd. |
|---|---|
| Business | Open-die forging factory |
| Address | No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China |
| Telephone, WhatsApp and WeChat | +86 189 2135 9659 |
| sales@steelforgepieces.com | |
| Website | www.steelforgepieces.com |
| Materials | Carbon steel, alloy steel, tool steel, stainless steel, nickel alloys |
| Melting routes | EAF plus VOD, with ESR remelt available |
| Certification supplied | EN 10204 3.1 with every order, 3.2 third party inspection on request |
| NDT standards | EN 10228-3, SEP 1921, ASTM A388 |
| Minimum order | One piece |
| Markets served | Worldwide |
Grades buyers compare against F310MoLN
- A182 F44
- 904L
- Sanicro 28
- Alloy 24
- A182 F316
- A182 F347
- A182 F321
- A182 F51
- A182 F53
- A182 F55
- A182 F61
- Alloy 31
- Incoloy 825
- Incoloy 926
If the drawing calls for something outside this list, the full range is on the stainless steel forgings and nickel alloy forgings pages.
Send us your A182 F310MoLN drawing
Email the drawing with quantity, delivery condition and certificate requirement, and a price and lead time come back to you. If the geometry is awkward to forge, we will say so and suggest an alternative rather than quote something that causes trouble later.
Property data on this page is compiled from published ASTM A182 / A182M F310MoLN and EN 1.4466 datasheets and is given for enquiry and preliminary design. The EN 10204 certificate issued with the forging is the governing document. Last updated 29 September 2026.