Grade data
The composition below is the JIS G4304 range for SUS 329J3L. G4304 itself covers plate, sheet and strip, so forgings are ordered against a forging specification, normally ASTM A182 F51, EN 10222-5 for 1.4462, or JIS G 3214 for stainless steel forgings for pressure vessels. The analysis stays inside this envelope either way.
| Limit | C | Si | Mn | P | S | Ni | Cr | Mo | N |
|---|---|---|---|---|---|---|---|---|---|
| Minimum | – | – | – | – | – | 4.50 | 21.00 | 2.50 | 0.08 |
| Maximum | 0.030 | 1.00 | 2.00 | 0.040 | 0.030 | 6.50 | 24.00 | 3.50 | 0.20 |
Nitrogen is what separates this grade from the older 329 duplex steels. It stabilises austenite, raises proof strength and lifts pitting resistance, and it is the reason vacuum oxygen decarburisation matters here. Cutting carbon to 0.030 percent while holding nitrogen inside a 0.08 to 0.20 percent window is a refining job, not a ladle addition.
| 0.2 percent proof stress | Tensile strength | Elongation | Hardness HV | Hardness HB | Hardness HRB |
|---|---|---|---|---|---|
| 450 N/mm2 min | 620 N/mm2 min | 18 percent min | 320 max | 302 max | 32 max |
These are specification minima, not typical results. Actual values depend on section size, how much reduction the piece saw under the press and how fast the heart of the forging came through the quench. Heavy sections are the ones to watch, which is why we agree test location and acceptance values before the order goes in and report both on the certificate.
Equivalent grades
If your drawing calls out any of the designations below, this is the material.
| Standard or origin | Designation | Note |
|---|---|---|
| JIS, Japan | SUS 329J3L | Composition per JIS G4304 |
| UNS, USA | S31803 | The original 2205 range |
| ASTM A182 | F51 | Forged flanges, fittings, valves and parts |
| EN, Europe | 1.4462, X2CrNiMoN22-5-3 | EN 10088, EN 10222-5 for forgings |
| KS, Korea | STS 329J3L | Direct counterpart |
| AFNOR, France | Z3 CND 22-05 Az | Equivalent range |
| GOST, Russia | 02Ch22N5M3 | Equivalent range |
| BS, UK, withdrawn | 318S13 | Nitrogen not specified in the old BS range |
| ISO | CrNiMo 22-5-3 | Equivalent range |
| Trade name | Duplex 2205, SAF 2205 | Typical aim 22Cr, 5Ni, 3.2Mo, 0.18N |
| Later tightened grade | UNS S32205, A182 F60 | Cr 22.0 to 23.0, Mo 3.0 to 3.5, N 0.14 to 0.20 |
| Cast counterpart | CD3MN, J92205 | For reference when matching castings |
Worth stating on the enquiry. S31803 and S32205 share the material number 1.4462, but S32205 pushes chromium, molybdenum and nitrogen up at the bottom end of the range. For chloride service, sour service or anything that will be welded on site, ask for dual certified S31803 and S32205 so the delivered analysis sits in the higher window. We aim the heat either way, but only if it is written into the order before melting.
Why buyers choose it
Two properties drive the specification. The first is strength. At 450 N/mm2 minimum proof stress the grade carries roughly twice the load of a 316L forging of the same section, so vessel walls, flanges and shafts come out lighter and the machining bill drops with them.
The second is chloride stress corrosion cracking. Austenitic 304 and 316 crack in hot chloride service, and that single failure mode is behind most of the duplex orders we forge. SUS 329J3L also resists intergranular corrosion and pitting, with a pitting resistance equivalent number of about 35 using the usual Cr plus 3.3Mo plus 16N calculation. For scale, 2205 duplex sits near 35 and the super duplex grades run above 42, so if your chloride level or temperature is at the edge of what 2205 handles, look at A182 F55 instead and we will quote both.
The trade is machinability. Duplex work hardens fast and chews tooling compared with 316L, so cutting speeds come down, feeds stay up, and setups need to be rigid enough to keep the tool cutting rather than rubbing a hardened skin. Most customers send us the finished drawing for that reason and take the part proof machined or fully machined.
How we make it
Most forging suppliers in China buy billet. This works starts at the furnace, so a SUS 329J3L part traces back to its own melt number rather than to a purchased bar of unknown history.
Melting and refining
Maximum heat size is 60 tonnes. Duplex runs through the electric arc furnace, is refined in a ladle furnace for desulphurisation and alloy trim, then decarburised under vacuum in a 30 or 60 tonne VOD vessel to bring carbon down and hold nitrogen where the specification wants it. Where cleanliness has to be tighter than normal, the grade can take the protective atmosphere electroslag route instead.
Forging and ring rolling
Hot work runs on open-die presses of 6,300, 4,000 and 2,000 tonnes, backed by hammers from 750 kg to 5 tonnes for drawing out and small batches. Rings are rolled on radial-axial mills of 6 m, 3 m and 1 m, and rings smaller than the mill range are upset and punched instead. Duplex has a narrower hot working window than carbon steel, so reheat temperature and finishing temperature are set per piece and the reduction is planned in the direction the part will be tested, circumferential for rings and axial for shafts.
Heat treatment
Solution annealing at 1020 to 1100 degrees C, then straight into water. The quench is the part of the process that decides whether the forging passes: cool it slowly and intermetallic phases form, taking toughness and corrosion resistance with them. Fourteen furnaces are on site, including car bottom furnaces up to 8,000 mm long and two pit furnaces 15,000 mm deep for vertical quenching of long shafts, so heavy duplex sections get out of the furnace and into the tank without waiting.
Machining, testing and documents
Vertical lathes turn to 5,000 mm swing, horizontal lathes to 14,000 mm between centres, and a CNC deep hole driller handles bores to 1,600 mm diameter by 10,000 mm. Ultrasonic examination follows EN 10228-3, SEP 1921 or ASTM A388 as specified. Chemical analysis and mechanical tests come as standard, and ferrite content measurement, intergranular corrosion testing to ASTM A262 and pitting tests to ASTM G48 are available on request. Certificates are issued to EN 10204-3.1, or 3.2 with a third party witnessing. The works holds CCS, BV, DNV, LR and NK approvals.
Size range
Limits below are set by the equipment on site, not by what a trader can source.
| Product | Limit | Set by |
|---|---|---|
| Seamless rolled rings | OD 50 to 6,000 mm | 6 m radial-axial ring mill, upset and punch route below mill range |
| Forged shafts | up to 14,000 mm turned length | Horizontal lathe, 15 m pit furnace for vertical quench |
| Discs, tube sheets, blocks | up to 5,000 mm diameter | 5,000 mm vertical turning lathe |
| Bored cylinders, hollow shafts | 1,600 mm dia by 10,000 mm | CNC deep hole drilling machine |
| Single piece weight | up to 30,000 kg | 60 t heat size, 6,300 t press |
| Order quantity | from 10 kg | No minimum piece count |
| Lead time | 20 to 60 days | Depends on melt scheduling and machining scope |
Forged forms in SUS 329J3L
Everything here is made to drawing or specification. There is no stock catalogue.
- Seamless rolled ringsRectangular and contoured sections, gear ring blanks, slewing rings, bearing races.
- Forged ringsUpset and punched rings outside the mill envelope, retaining rings, valve seat rings.
- FlangesWeld neck, blind, slip-on, socket weld, lap joint, orifice and long weld neck to ASME B16.5, B16.47 and API 6A.
- Shafts and spindlesStepped shafts, gear and pinion shafts, eccentric shafts, crankshafts, rotors, tie rods.
- Bars, blocks and blanksRound, flat and square bars as feedstock for machined bodies and tooling.
- Discs and tube sheetsSolid forged discs, tube sheets and covers, supplied proof machined for volumetric inspection.
- Valve and wellhead partsBodies, bonnets, stems, seat rings, spools, nozzles, manifolds, sleeves, bushings. API 6A and NACE MR0175 / ISO 15156 scope available.
- Cylinders and heavy wall pipeHollow cylinders, couplings and pipe sections bored from solid forged blanks.
Where it is used
Oil, gas and offshore. Subsea and deepwater production hardware, wellhead and Christmas tree components, manifolds, blowout preventer and riser parts, and downhole duty in moderately corrosive sour gas wells where chloride cracking rules out austenitic grades.
Chemical and petrochemical plant. Pressure vessel and heat exchanger components, tube sheets, separator internals, crystalliser equipment, pump and valve parts in chloride bearing media.
Marine and desalination. Seawater desalination plant parts, shipbuilding hardware, pump and compressor components in seawater service.
Pulp and paper. Digesters, liquor tanks, paper machine rolls and press rolls, where chlorides and abrasion arrive together.
Power and rotating equipment. Turbine and gas compressor parts, gearbox components, generator and nitrogen generator parts, industrial air compressors, transmission shafts.
Questions we get asked
Is SUS 329J3L the same as 2205?
For practical purposes yes. SUS 329J3L covers the same range as UNS S31803, sold as 2205 and called F51 in ASTM A182. The later S32205, or F60, narrows the ranges upward for more consistent corrosion behaviour and weldability. Both carry the European number 1.4462.
Can you dual certify to S31803 and S32205?
Yes, provided it is specified before the heat is melted. Since we run our own furnace and VOD vessel we aim chromium, molybdenum and nitrogen at the overlap of both ranges rather than hoping a purchased billet lands there.
Why does the quench matter so much on duplex?
Because the ferrite and austenite phases will shed intermetallics if the piece cools slowly, and those phases cut impact toughness and corrosion resistance. Heavy sections are the risk, which is why furnace to tank distance and quench capacity decide whether a thick duplex forging can be made properly at all.
Do you supply material for sour service?
We forge, heat treat and test to the hardness and microstructure requirements normally invoked under NACE MR0175 / ISO 15156, and add ferrite content and corrosion testing to the test plan. Send the full specification including any client document and hardness cap so it is written into the order.
What is the smallest order you accept?
10 kg, with no minimum piece count. Lead time runs 20 to 60 days depending on where the grade sits in the melt schedule and how much machining is in scope.
What documents come with the forgings?
EN 10204-3.1 as standard, or EN 10204-3.2 with third party inspection. Ultrasonic reports to EN 10228-3, SEP 1921 or ASTM A388 as agreed. Traceability runs from the melt number through forging and heat treatment to the shipped part.
Quote a SUS 329J3L forging
Send a drawing, or just the dimensions, quantity, delivery condition and test requirements. We come back inside one working day with a price, a weight and the melt and heat treatment plan. If the part suits a different duplex or austenitic grade better, we will say so in the same reply.