Duplex stainless steel / EN 1.4460
X3CrNiMoN27-5-2, material number EN 1.4460, is an austenitic-ferritic duplex stainless steel with 25 to 28 percent chromium, 4.5 to 6.5 percent nickel, 1.3 to 2.0 percent molybdenum and 0.05 to 0.20 percent nitrogen. The two-phase structure carries a proof strength of at least 460 MPa, roughly twice that of a standard austenitic grade, together with resistance to pitting, crevice corrosion, chloride stress corrosion cracking and corrosion fatigue.
Jiangyin Jiangnan Metal Co., Ltd. melts this grade in-house through the electric arc furnace, ladle furnace and vacuum oxygen decarburisation route, then forges, heat treats, machines and certifies it on the same site. The certificate traces the part to its melt number rather than to a purchased billet.
Limits for X3CrNiMoN27-5-2 as listed in EN 10088, percent by weight.
| C | Si | Mn | P | S | Cr | Ni | Mo | N | Fe |
|---|---|---|---|---|---|---|---|---|---|
| ≤ 0.05 | ≤ 1.00 | ≤ 2.00 | ≤ 0.035 | ≤ 0.030 | 25.0–28.0 | 4.5–6.5 | 1.30–2.00 | 0.05–0.20 | Balance |
Sulphur is a choice, not a leftover. EN 10088-3 states that a controlled sulphur content of 0.015 to 0.030 percent is recommended and permitted for machinability, 0.008 to 0.030 percent for weldability, and 0.015 percent maximum for polishability. The three cannot all be optimised in one heat. State which one governs your part on the enquiry and the melt is aimed at it.
Specified values apply to the solution annealed condition. Typical values are measured figures published for the grade and are given for design guidance, not as order guarantees.
| Property | Symbol | Value |
|---|---|---|
| Tensile strength | Rm | 620–880 MPa |
| 0.2 % proof strength | Rp0.2 | ≥ 460 MPa |
| Elongation | A | ≥ 20 % |
| Hardness, annealed | HB | ≤ 260 |
| Modulus of elasticity | E | 200 GPa |
| Property | Metric | Imperial |
|---|---|---|
| Ultimate tensile strength | 750 MPa | 110 ksi |
| Yield / proof strength | 510 MPa | 74 ksi |
| Elongation at break | 21 % | 21 % |
| Brinell hardness | 220 HB | 220 HB |
| Charpy V-notch impact | 83 J | 61 ft-lb |
| Fatigue strength | 330 MPa | 48 ksi |
| Shear strength | 470 MPa | 68 ksi |
| Shear modulus | 80 GPa | 12 x 10⁶ psi |
| Poisson's ratio | 0.27 | 0.27 |
| Temperature | Rp0.2 | Modulus E | Linear expansion |
|---|---|---|---|
| 20 °C | ≥ 460 MPa | 200 GPa | – |
| 100 °C | ≥ 360 MPa | 194 GPa | 13.0 x 10⁻⁶ K⁻¹ |
| 200 °C | ≥ 310 MPa | 186 GPa | 13.5 x 10⁻⁶ K⁻¹ |
| 300 °C | – | 180 GPa | 14.0 x 10⁻⁶ K⁻¹ |
| Density | 7.8 g/cm³ |
|---|---|
| Thermal conductivity | 15 W/m·K |
| Specific heat capacity | 480 J/kg·K |
| Thermal expansion | 13 µm/m·K |
| Latent heat of fusion | 300 J/g |
| Melting onset (solidus) | 1390 °C |
| Melting completion (liquidus) | 1430 °C |
| Maximum temperature, corrosion service | 450 °C |
Temperature limit. Like other duplex steels, 1.4460 embrittles after long exposure between roughly 300 and 900 °C, where sigma phase and 475 °C embrittlement develop. Design continuous service below about 300 °C, and below about 450 °C in corrosive media. The grade is not a creep-resisting material. For hotter duty ask about AISI 321H or Incoloy 800H.
Cross-references for 1.4460 are not consistent across the trade literature, and the disagreement is worth stating plainly. Virgamet and Langley Alloys both equate 1.4460 with AISI 329 and UNS S32900. The duplex comparison table on Wikipedia maps 1.4460 to UNS S31200. The compositions below show why both can be argued: each overlaps 1.4460 without matching it.
| Standard | Designation | Cr % | Ni % | Mo % | N % |
|---|---|---|---|---|---|
| EN / DIN | X3CrNiMoN27-5-2 · 1.4460 | 25.0–28.0 | 4.5–6.5 | 1.30–2.00 | 0.05–0.20 |
| ASTM / AISI | AISI 329 · S32900 · Alloy 7Mo | 23.0–28.0 | 2.5–5.0 | 1.00–2.00 | – |
| ASTM | S31200 · 44LN · Grade F50 | 24.0–26.0 | 5.5–6.5 | 1.20–2.00 | 0.14–0.20 |
| AFNOR | Z5CND27-05 Az | 26.0–27.0 | 4.5–5.0 | 1.30–2.00 | 0.05–0.20 |
| SS (Sweden) | SS 2324 | 24.0–27.0 | 4.5–7.0 | 1.30–1.80 | – |
| UNE (Spain) | X8CrNiMo26-6 · F-3552 | 24.0–27.0 | 4.5–7.0 | 1.30–1.80 | ≤ 0.10 |
| UNE (Spain) | X8CrNiMo27-05 · F-3309 | 26.0–28.0 | 4.0–5.0 | 1.30–2.00 | – |
| ASTM cast | CD6MN · J93371 · A781 Gr. 3A | 24.0–27.0 | 4.0–6.0 | 1.75–2.50 | 0.15–0.25 |
Order against the EN 1.4460 limits and name the standard your project is audited to. We confirm in writing, before melting, whether one heat can satisfy both the EN grade and the ASTM designation you need.
The duplex structure, 25 to 28 percent chromium and 1.3 to 2.0 percent molybdenum give good resistance to pitting, crevice corrosion, intergranular corrosion, corrosion fatigue and chloride stress corrosion cracking. That last one is the failure mode that takes out 304 and 316 in warm chloride service, and it is the usual reason buyers move to this grade. Resistance to intergranular attack is retained after welding.
The calculated pitting resistance equivalent number is about 34, using the formula %Cr + 3.3 x %Mo + 16 x %N. For comparison, a PREN of 32 to 35 is the figure commonly treated as the minimum for seawater service, and super duplex grades sit near 40 and above. That places 1.4460 at the lower edge of seawater capability. It suits many chloride-bearing process streams, but for hot aerated seawater or sour service, compare it against A182-F53 or A182-F55 first.
Some suppliers list 1.4460 in the super duplex group because of its chromium content. The PREN figure is the more reliable test of that claim, and on PREN this grade is a standard duplex.
This is where the grade earns its place. With a controlled sulphur content it machines more easily than 1.4462, which suits parts needing heavy turning, drilling and threading. The trade-off is real: corrosion resistance is slightly lower than 1.4462, and raising sulphur for machinability costs polishability.
Weldable, with intergranular corrosion resistance retained after welding. Weld as an austenitic material with low and controlled heat input and a held interpass temperature, to protect the ferrite to austenite balance. Confirm filler choice against your welding procedure.
Can be hot and cold formed. Duplex steels work-harden faster and spring back more than austenitics, so allow higher forming loads than for 316. After hot forming, a full solution anneal and quench restores the phase balance and the corrosion resistance.
Supplied solution annealed and quenched. Strength comes from the duplex microstructure, not from precipitation, so the grade is not hardenable by heat treatment. Avoid slow cooling through the sigma phase range.
Every piece is forged from steel melted on this site. No casting, no welded fabrication, no purchased billet of unknown origin.
| Product | Size limit | Set by |
|---|---|---|
| Seamless rolled rings | to OD 6,000 mm | 6 m radial-axial ring mill |
| Forged shafts | to 14,000 mm turned length | C61160 lathe, 15 m well furnace for vertical quench |
| Discs, tube sheets, blocks | to 5,000 mm machined dia. | 5,000 mm vertical turning lathe |
| Bored cylinders, hollow shafts | to 1,600 mm dia. x 10,000 mm | CNC deep-hole drilling machine |
| Single-piece weight | to 30,000 kg | 60 t heat size, 6,300 t press |
| Minimum ring size | from OD 50 mm | Upset and punch route below ring-mill range |
X3CrNiMoN27-5-2 is specified where chloride attack and mechanical load arrive together. Documented application areas include pumps and pump shafts, valves and valve parts, screws, heat exchangers for power engineering, radiators, tanks, chlorine-bearing housings, pipelines, special anchors, stirrers and sleeves, across chemical, cryogenic, pulp and paper, marine and aviation plant. Marine propeller shafting, pump shafting, pistons, bolts and nuts are the common forged applications.
EN 10204 3.1 mill test certificates come as standard, with 3.2 third-party certification on request. Because the steel is melted here, the certificate traces back to the melt number rather than stopping at a purchased billet. The works holds CCS, BV, DNV, LR and NK approvals.
| Test | Purpose |
|---|---|
| Spectrometer analysis | Confirms composition against EN 10088 limits, including nitrogen |
| Tensile and proof strength | Room or elevated temperature, per EN 10088-3 or the order standard |
| Charpy V-notch impact | Toughness, including sub-zero where the duty calls for it |
| Brinell hardness | Verifies the annealed condition |
| Ferrite content | Checks the ferrite to austenite balance after forging and annealing |
| Microstructure | Screens for sigma phase and intermetallic precipitation |
| Ultrasonic and dye penetrant | Volumetric and surface soundness of the forging |
| Intergranular corrosion | Confirms resistance in the as-delivered and as-welded condition |
| ASTM G48 pitting | Critical pitting temperature for chloride service |
Name the test package with the enquiry so it is priced into the quotation rather than added later.
X3CrNiMoN27-5-2, material number EN 1.4460, is an austenitic-ferritic duplex stainless steel with 25.0 to 28.0 percent chromium, 4.5 to 6.5 percent nickel, 1.30 to 2.00 percent molybdenum and 0.05 to 0.20 percent nitrogen. The two-phase structure gives a proof strength of at least 460 MPa, about double that of a standard austenitic grade, with resistance to pitting, crevice corrosion, chloride stress corrosion cracking and corrosion fatigue. It is listed in EN 10088-1, EN 10088-3 and EN 10088-5, in EN 10250-4 for open die forgings, and in EN 10297-2 for seamless tube.
Published cross-references disagree. Virgamet and Langley Alloys equate 1.4460 with AISI 329 and UNS S32900. The duplex comparison table on Wikipedia maps it to UNS S31200. Other near-equivalents are AFNOR Z5CND27-05 Az, Swedish SS 2324, Spanish F-3552 and F-3309, and the cast grade CD6MN or UNS J93371 under ASTM A781 Grade 3A. None matches exactly, so order against the EN 1.4460 limits and have the cross-reference confirmed in writing before melting.
It sits in the standard duplex band. The calculated PREN is about 34, below the value near 40 that normally defines super duplex grades such as 1.4410 or UNS S32750. Some suppliers do market 1.4460 as super duplex on the strength of its 25 to 28 percent chromium, so check the PREN rather than the label when the specification matters.
1.4460 machines more easily than 1.4462 but has slightly lower corrosion resistance. EN 10088-3 permits a controlled sulphur content of 0.015 to 0.030 percent where machinability matters, which is how the machinability-improved versions of this grade are made. Pick 1.4460 for parts with heavy machining content in moderate chloride duty, and 2205 / F51 where corrosion margin governs.
Yes. The grade is weldable and keeps its intergranular corrosion resistance after welding in the solution annealed condition. Use low and controlled heat input and avoid long exposure between roughly 300 and 900 °C, where duplex steels embrittle. Continuous service in corrosive media is normally kept below about 450 °C.
The works runs a 6,300 tonne open-die press and a 6 metre radial-axial ring mill, giving rolled rings to 6,000 mm outside diameter and single pieces to 30 tonnes. Shafts can be turned to 14,000 mm, discs to 5,000 mm diameter, and bored cylinders to 1,600 mm diameter by 10,000 mm long. Minimum order is 10 kg with no minimum piece count, and lead time runs 20 to 60 days.
EN 10204 3.1 as standard, 3.2 third-party certification on request. Chemical analysis, tensile, impact, hardness, ferrite content, microstructure, ultrasonic and dye penetrant examination, intergranular corrosion testing and ASTM G48 pitting tests can all be included. The works holds CCS, BV, DNV, LR and NK approvals.
Send a drawing, or just the grade, dimensions, quantity and test standard. You get back a forged weight, a price and a lead time. Minimum order 10 kg, no minimum piece count.