1.4406 (X2CrNiMoN17-11-2) Stainless Steel Forgings
Nitrogen-alloyed 316LN, UNS S31653, ASTM A182 F316LN. Technical data and open-die forging capability.
What is 1.4406 stainless steel?
1.4406 is the EN 10088 material number for the steel designated X2CrNiMoN17-11-2: an austenitic stainless steel alloyed with 16.5 to 18.5% chromium, 10.0 to 12.5% nickel, 2.00 to 2.50% molybdenum and 0.12 to 0.22% nitrogen, with carbon restricted to 0.030% maximum.
Chromium and molybdenum carry the corrosion resistance. Capping carbon at 0.030% keeps chromium carbides from forming at the grain boundaries during welding or slow cooling, which is what makes the grade weld-repairable without a stabilising heat treatment. Nitrogen is the addition that separates it from 316L. It strengthens the austenite in solid solution, and unlike cold work it costs nothing in ductility or toughness. Designers spend that extra strength on thinner pressure-retaining sections than 316L would allow at the same allowable stress.
Nitrogen also stabilises austenite, which is why the nickel band of 1.4406 sits a little lower than that of 1.4404. The grade remains fully austenitic on 10.0% nickel where 1.4404 needs more.
1.4406 equivalent grades and designations
| System or standard | Designation | Notes |
|---|---|---|
| EN material number | 1.4406 | EN 10088-1 |
| EN chemical designation | X2CrNiMoN17-11-2 | EN 10088-1 |
| AISI / ASTM type | 316LN | Nitrogen-alloyed low-carbon 316 |
| UNS | S31653 | Shared with 1.4429 |
| ASTM A182 forging grade | F316LN | Flanges, fittings, valve parts |
| ASTM A240 / A276 | 316LN | Plate and bar |
| JIS (Japan) | SUS316LN | JIS G 4303 / G 4304 |
| BS (UK, superseded) | 316S61 | BS 970 / BS 1501 |
| AFNOR (France) | Z3CND17-11Az | NF A 35-573 |
| ISO | 4406-316-53-I | ISO 15510 |
| GB (China) | 022Cr17Ni12Mo2N | Nearest GB/T 20878 match |
Product standards that specify 1.4406
- EN 10088-2, sheet, plate and strip for general corrosion-resisting purposes.
- EN 10088-3, semi-finished products, bars, rods, wire and sections. This is the correct reference for forged and rolled bar.
- EN 10250-4, open-die steel forgings for general engineering purposes, stainless steels.
- EN 10222-5, steel forgings for pressure purposes, austenitic stainless steels.
- EN 10272, stainless steel bars for pressure purposes.
- EN 10028-7, flat products for pressure purposes, stainless steels.
- ASTM A182 / A182M, grade F316LN forged flanges, fittings, valves and parts.
1.4406 is not A182 F62. ASTM A182 grade F62 is UNS S31254, the 6Mo super-austenitic steel also known as EN 1.4547 or 254 SMO. It carries roughly 6% molybdenum and a PREN above 40, which puts it in a different alloy class and a different price bracket. The A182 grade that matches 1.4406 is F316LN. For 6Mo material see our A182 F44 / 1.4547 page.
Chemical composition of 1.4406
| C | Si | Mn | P | S | Cr | Ni | Mo | N |
|---|---|---|---|---|---|---|---|---|
| ≤ 0.030 | ≤ 1.00 | ≤ 2.00 | ≤ 0.045 | ≤ 0.015 | 16.5 to 18.5 | 10.0 to 12.5 | 2.00 to 2.50 | 0.12 to 0.22 |
Sulphur control
Controlled sulphur is permitted where one property has to be optimised, and the range is fixed at enquiry: 0.015 to 0.030% for machinability, 0.008 to 0.030% for weldability, and 0.015% maximum where the surface has to take a high polish. Elements not listed in Table 2 are not intentionally added without the purchaser's agreement, other than for finishing the cast.
Calculated PREN
Pitting resistance equivalent number, PREN = %Cr + 3.3 × %Mo + 16 × %N:
| Grade | At minimum limits | At maximum limits | Typical production cast |
|---|---|---|---|
| 1.4406 / 316LN | 25.0 | 30.3 | about 26 |
| 1.4404 / 316L | 23.1 | 28.4 | about 24 |
The gap comes almost entirely from nitrogen, which carries a weighting of 16 in the formula against 3.3 for molybdenum.
Mechanical properties of 1.4406
Values apply to the solution annealed condition (+AT) at room temperature, for bar, rod and section to EN 10088-3. Forgings to EN 10250-4 and EN 10222-5 are tested on the same basis, with heavy sections tested on a prolongation of the forging.
| Property | Symbol | Direction | Requirement |
|---|---|---|---|
| 0.2% proof strength, min. | Rp0.2 | Any | 280 MPa |
| 1.0% proof strength, min. | Rp1.0 | Any | 315 MPa |
| Tensile strength | Rm | Any | 580 to 800 MPa |
| Elongation after fracture, min. | A | Longitudinal | 40% |
| Elongation after fracture, min. | A | Transverse | 30% |
| Impact energy ISO-V at +20 °C, min. | KV | Longitudinal | 100 J |
| Impact energy ISO-V at +20 °C, min. | KV | Transverse | 60 J |
| Impact energy ISO-V at −196 °C, min. | KV | Transverse | 60 J |
| Brinell hardness, max. | HBW | Any | 250 |
Above 160 mm and up to 250 mm, EN 10088-3 permits reduced proof and tensile values. Heavy forgings are tested on a prolongation. We confirm the acceptance values for your exact section at the enquiry stage.
Elevated-temperature and cryogenic behaviour
Proof strength falls steadily with temperature, as it does for every austenitic stainless steel, but 1.4406 keeps a clear margin over 1.4404 across the range because the nitrogen stays in solid solution. Minimum Rp0.2 values at 50 °C intervals are tabulated in EN 10088-3, and for pressure parts in EN 10222-5 and EN 10028-7. Those values depend on thickness and product form and the standards get revised, so we quote the figures for your section against the current edition rather than publish a generic table here. Ask us and they go out with the quotation.
Going the other way there is no penalty at all. The face-centred-cubic structure has no ductile-to-brittle transition, so Charpy energy holds at −196 °C and below, and EN 10088 sets no lower metal temperature limit above −270 °C.
1.4406 cannot be hardened by heat treatment. Strength above the annealed level comes only from cold work, which raises proof strength quickly but costs elongation and brings in a slight magnetic response.
Physical properties of 1.4406
| Property | Value | Condition |
|---|---|---|
| Density | 8.0 g/cm³ (8000 kg/m³) | 20 °C |
| Modulus of elasticity | 200 GPa | 20 °C |
| Modulus of elasticity | 186 / 172 GPa | 200 / 400 °C |
| Coefficient of thermal expansion | 16.0 × 10−6 K−1 | 20 to 100 °C |
| Coefficient of thermal expansion | 17.0 × 10−6 K−1 | 20 to 300 °C |
| Thermal conductivity | 15 W/(m·K) | 20 °C |
| Specific heat capacity | 500 J/(kg·K) | 20 °C |
| Electrical resistivity | 0.75 Ω·mm²/m | 20 °C |
| Magnetisable | No (μr < 1.05) | Solution annealed |
| Melting range | about 1390 to 1440 °C | Reference only |
Corrosion resistance and service limits
EN 10088 records 1.4406 as resistant to intergranular corrosion both in the delivery condition and in the sensitised condition. That double rating follows directly from the 0.030% carbon ceiling, and it is the reason welded joints and heat-affected zones need no stabilising treatment in normal service.
- Pitting and crevice corrosion. PREN 25 to 30 is useful in moderate chloride environments. It beats 1.4404 but sits well below the 6Mo grades. Weight for weight nitrogen is roughly five times more effective than chromium at suppressing pit initiation, which is where the improvement comes from.
- Chloride stress-corrosion cracking. Like every 300-series austenitic, 1.4406 stays vulnerable above roughly 60 °C in chloride solutions under tensile stress. Where SCC governs the design, duplex grades such as 1.4462 / F51 or 1.4410 / F53 are the usual substitutes.
- Acids. Good in dilute sulphuric, phosphoric and organic acids. Molybdenum extends service into reducing conditions that would attack 1.4301 / 304.
- Low temperature. No lower metal temperature limit above −270 °C.
- High temperature. Creep normally caps pressure-retaining design temperature around 550 °C. Avoid prolonged exposure between 425 and 850 °C, where sigma phase forms and embrittles the steel.
Forging and heat treatment of 1.4406
| Operation | Parameter | Remarks |
|---|---|---|
| Forging and hot working | 1150 to 1200 °C | Soak to through-heat. Nitrogen raises hot strength, so press capacity is sized accordingly |
| Finishing temperature | 900 °C minimum | Forging below this risks cracking and leaves an unrecrystallised structure |
| Solution annealing | 1020 to 1120 °C | Rapid quench, normally water. Mandatory after forging to restore full austenite |
| Stress relief | Not normally applied | Agreed with the purchaser if required. Avoid soaking between 425 and 850 °C |
| Hardening | Not possible by heat treatment | Strength comes from nitrogen in solid solution and from cold work |
| Descaling and pickling | HNO3 / HF pickle, or blast and passivate | Restores the passive layer after hot work |
Welding
All common arc processes apply: GTAW, SMAW, GMAW, SAW. Consumables are matching or slightly over-alloyed, normally ER316LN, ER316L or ER318 / E316L-16. No preheat is needed and post-weld heat treatment is generally unnecessary. Keep interpass temperature and heat input moderate, and back the root with argon to protect the reverse face.
Machining
1.4406 machines much like 316L but work-hardens faster because of the nitrogen. Use sharp positive-rake tooling, rigid setups, heavy constant feed to stay under the work-hardened layer, and plenty of coolant. Reckon on 55 to 60% of the machinability rating of free-machining 1.4305.
1.4406 open-die forged products we manufacture
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China. We forge 1.4406 / X2CrNiMoN17-11-2 to customer drawings and to EN 10250-4, EN 10222-5 and ASTM A182 F316LN.
| Product form | Size range | Typical applications |
|---|---|---|
| Round bars and shafts | Ø 80 to 1200 mm, length to 8000 mm | Pump and valve shafts, pins, tie rods |
| Square, rectangular, flat and hex bars | 50 to 800 mm section | Machined blocks, die blanks, structural parts |
| Hollow bars, sleeves, bushings | OD 150 to 1500 mm, ID from 60 mm | Cylinders, casings, bushes, liners |
| Seamless rolled rings | OD 200 to 4000 mm, height to 1000 mm | Flanges, tube sheets, bearing races, gear blanks |
| Discs, blocks, plates | Ø to 2500 mm, thickness 40 to 800 mm | Blind flanges, covers, valve bodies |
| Forged flanges | WN, SO, BL, LJ to ASME B16.5 / B16.47 / EN 1092-1 | Piping, pressure vessels |
| Step shafts, hubs, housings, cases | To drawing | Rotating equipment, subsea and offshore |
Maximum single piece weight is about 20 tonnes. Everything is supplied solution annealed unless a different delivery condition is specified on the order.
Applications of 1.4406 forgings
Pressure equipment
Vessel shells, nozzles, covers and forged flanges, where the higher allowable stress cuts wall thickness against 316L.
Cryogenic and LNG
Valve bodies, flanges and pump parts for liquid natural gas, oxygen and nitrogen service down to −270 °C.
Chemical and petrochemical
Reactor internals, heat-exchanger tube sheets, pump and valve components in moderately chloride-bearing streams.
Nuclear and fusion
316LN-type steel is a standard structural grade for reactor internals and superconducting magnet structures.
Offshore and marine
Topside and subsea fittings, manifold blocks, instrumentation forgings.
Pharmaceutical and food
Polishable, low-carbon, weld-repairable forgings for hygienic process equipment.
1.4406 compared with neighbouring grades
| Grade | EN name | US | Mo % | N % | Rp0.2 min | Rm | PREN |
|---|---|---|---|---|---|---|---|
| 1.4404 | X2CrNiMo17-12-2 | 316L | 2.00 to 2.50 | ≤ 0.10 | 200 MPa | 500 to 700 | 23 to 28 |
| 1.4406 | X2CrNiMoN17-11-2 | 316LN | 2.00 to 2.50 | 0.12 to 0.22 | 280 MPa | 580 to 800 | 25 to 30 |
| 1.4429 | X2CrNiMoN17-13-3 | 316LN, high Mo | 2.50 to 3.00 | 0.12 to 0.22 | 280 MPa | 580 to 800 | 27 to 32 |
| 1.4435 | X2CrNiMo18-14-3 | 316L, high Mo | 2.50 to 3.00 | ≤ 0.11 | 200 MPa | 500 to 700 | 25 to 31 |
| 1.4571 | X6CrNiMoTi17-12-2 | 316Ti | 2.00 to 2.50 | Not specified | 200 MPa | 500 to 700 | 23 to 27 |
| 1.4462 | X2CrNiMoN22-5-3 | F51 / 2205 | 2.50 to 3.50 | 0.10 to 0.22 | 450 MPa | 650 to 880 | 31 to 38 |
How to choose
- More strength than 316L at the same corrosion resistance and the same weldability: 1.4406.
- Same strength, more pitting resistance: 1.4429.
- Chloride stress-corrosion cracking above 60 °C is the controlling risk: duplex 1.4462 / F51.
- Seawater or high-chloride service: 6Mo 1.4547 / F44, or a nickel alloy.
Testing, inspection and certification
Chemistry
Optical emission spectrometry on ladle and product analysis. PMI on request.
Mechanical testing
Tensile to EN ISO 6892-1 or ASTM A370. Charpy V to EN ISO 148-1 at ambient or down to −196 °C. Brinell hardness.
Corrosion testing
Intergranular corrosion to ASTM A262 Practice E or EN ISO 3651-2. ASTM G48 pitting on request.
Non-destructive testing
Ultrasonic to EN 10228-3, ASTM A388 or SEP 1921. Liquid penetrant to EN ISO 3452 or ASTM E165.
Metallography
Grain size to ASTM E112, ferrite number, macro-etch for flow lines and soundness.
Documentation
EN 10204 3.1 mill certificate as standard. 3.2 with third-party witness on request.
Frequently asked questions about 1.4406
What is 1.4406 stainless steel?
1.4406 is the EN material number for X2CrNiMoN17-11-2, a nitrogen-alloyed, low-carbon austenitic stainless steel containing 16.5 to 18.5% chromium, 10.0 to 12.5% nickel, 2.00 to 2.50% molybdenum and 0.12 to 0.22% nitrogen, with carbon below 0.030%. It is the nitrogen-strengthened version of 316L, specified in EN 10088-2, EN 10088-3, EN 10250-4 and EN 10222-5.
What is the American equivalent of 1.4406?
1.4406 corresponds to AISI 316LN, UNS S31653 and ASTM A182 grade F316LN. Elsewhere it is JIS SUS316LN in Japan, BS 316S61 in the UK and AFNOR Z3CND17-11Az in France. Chemical limits differ slightly between standards, so dual certification is agreed at the order stage.
What is the difference between 1.4406 and 1.4404 (316L)?
Nitrogen. 1.4404 limits nitrogen to 0.10% maximum, 1.4406 requires 0.12 to 0.22%. That raises the minimum 0.2% proof strength of solution annealed bar from 200 MPa to 280 MPa, an increase of 40%, and tensile strength from 500 to 700 MPa up to 580 to 800 MPa. Carbon stays below 0.030% in both, so resistance to intergranular corrosion is unchanged.
What is the difference between 1.4406 and 1.4429?
Both are nitrogen-alloyed 316LN-type steels with identical strength requirements, and both carry UNS S31653. 1.4406 (X2CrNiMoN17-11-2) has 2.00 to 2.50% Mo and 10.0 to 12.5% Ni. 1.4429 (X2CrNiMoN17-13-3) has 2.50 to 3.00% Mo and 11.0 to 14.0% Ni, giving a higher PREN and better pitting resistance in chloride service.
Is 1.4406 magnetic?
No. Solution annealed 1.4406 is fully austenitic and non-magnetic, with relative permeability below about 1.05. Heavy cold work can induce a little strain-induced martensite and a slight magnetic response, but forgings supplied solution annealed are non-magnetic.
What is the PREN of 1.4406?
Using PREN = %Cr + 3.3 × %Mo + 16 × %N, 1.4406 gives 25.0 at the minimum composition limits and 30.3 at the maximum, so it is quoted as PREN 25 to 30. A typical production cast sits near 26, two to three points above 1.4404 (316L).
Can 1.4406 be used at cryogenic temperatures?
Yes. EN 10088 sets no lower metal temperature limit above −270 °C, and the austenitic structure has no ductile-to-brittle transition, so impact toughness is retained to liquid helium temperature. The grade is used for LNG, liquid oxygen, liquid nitrogen and superconducting magnet components.
What is the forging temperature for 1.4406?
1.4406 is open-die forged from 1150 to 1200 °C and forging is finished above about 900 °C. The part is then solution annealed at 1020 to 1120 °C and quenched rapidly, normally in water, to dissolve carbides and restore the fully austenitic structure. The grade cannot be hardened by heat treatment.
Is 1.4406 weldable?
Yes. With carbon below 0.030% it welds by all common arc processes and needs no post-weld heat treatment in most thicknesses. Matching or over-alloyed fillers such as ER316LN, ER316L or ER318 are used. Keep heat input moderate and avoid prolonged exposure to 425 to 850 °C to prevent sigma phase.
Who supplies 1.4406 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, forges 1.4406 into round bars, hollow bars and sleeves, seamless rolled rings, discs, blocks, shafts and flanges, supplied solution annealed with EN 10204 3.1 or 3.2 certification. Enquiries: sales@steelforgepieces.com, +86 189 2135 9659.
Request a quotation for 1.4406 forgings
Send a drawing, or just the basics: grade, product form, finished or rough dimensions, quantity, delivery condition and certification level. Quotations normally go out within one working day.
About Jiangyin Jiangnan Metal Co., Ltd.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory based in Jiangyin, Jiangsu Province, China. We produce forged bars, hollow bars and sleeves, seamless rolled rings, discs and blocks, shafts, flanges and made-to-drawing forgings in stainless steel, carbon steel, alloy steel, tool steel, duplex stainless steel and nickel alloys, and ship worldwide with EN 10204 mill certification.
- Address
- No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- Telephone
- +86 189 2135 9659 (0086-189-2135-9659)
- sales@steelforgepieces.com
- Website
- www.steelforgepieces.com
- Business
- Open-die forging, seamless rolled rings, forged flanges and bars
- Markets served
- Worldwide. Enquiries handled in English and Chinese
Standards referenced
- EN 10088-1, Stainless steels. List of stainless steels.
- EN 10088-2, Technical delivery conditions for sheet, plate and strip.
- EN 10088-3, Technical delivery conditions for semi-finished products, bars, rods, wire and sections.
- EN 10250-4, Open die steel forgings for general engineering purposes. Stainless steels.
- EN 10222-5, Steel forgings for pressure purposes. Martensitic, austenitic and austenitic-ferritic stainless steels.
- EN 10272, Stainless steel bars for pressure purposes.
- EN 10204, Metallic products. Types of inspection documents.
- ASTM A182/A182M, Forged or rolled alloy and stainless steel pipe flanges, forged fittings, and valves and parts.
- ISO 15510, Stainless steels. Chemical composition.
Data on this page is compiled from the standards listed above together with our own production and test records. Figures are given for guidance. For design calculations use the current edition of the governing standard, and confirm the specification with us at the enquiry stage.