318S13 Duplex Stainless Steel Forgings
UNS S31803 · EN 1.4462 · X2CrNiMoN22-5-3 · ASTM A182 F51 · SUS 329J3L · Duplex 2205
318S13 is the British Standard designation for 22% chromium austenitic-ferritic duplex stainless steel. It is equivalent to UNS S31803, EN 1.4462 (X2CrNiMoN22-5-3), ASTM A182 F51 and JIS SUS 329J3L, and is sold commercially as Duplex 2205.
The two-phase ferrite and austenite structure gives a minimum 0.2% proof stress of 450 N/mm², about twice the 205 MPa of grade 316, with a pitting resistance equivalent number (PREN) of roughly 35 against about 24 for 316.
Jiangyin Jiangnan Metal Co., Ltd. forges 318S13 to customer drawing as rings, seamless rolled rings, flanges, shafts, round bars, discs, sleeves, bushings, tube sheets and hollow forgings. Material is solution annealed at 1020-1100 °C and ultrasonically tested to EN 10228-4.
Grade equivalents and cross reference
318S13 is the older British designation and appears in stockholder cross reference tables as the BS equivalent of 1.4462. For a modern purchase specification the designation normally required on the certificate is UNS S31803, or ASTM A182 F51 for forgings.
| Standard or system | Designation |
|---|---|
| BS (British) | 318S13, also written 318 S 13 |
| UNS | S31803. Revised grade: S32205 |
| EN 10088 / DIN | 1.4462, X2CrNiMoN22-5-3 |
| ASTM forging grade | A182 F51. F60 for S32205 |
| JIS | SUS 329J3L |
| AFNOR | Z3CND22-05AZ |
| GOST | 02Ch22N5M3 |
| ISO | CrNiMo22-5-3 |
| Trade names | SAF 2205, Duplex 2205, AISI 318LN |
| Cast equivalent | CD3MN, J92205 |
Chemical composition of 318S13
| Element | 318S13 / S31803 / 1.4462 | S32205 (A182 F60) |
|---|---|---|
| Carbon, C | 0.030 max | 0.030 max |
| Chromium, Cr | 21.0 - 23.0 | 22.0 - 23.0 |
| Nickel, Ni | 4.5 - 6.5 | 4.5 - 6.5 |
| Molybdenum, Mo | 2.5 - 3.5 | 3.0 - 3.5 |
| Nitrogen, N | 0.08 - 0.20 | 0.14 - 0.20 |
| Manganese, Mn | 2.00 max | 2.00 max |
| Silicon, Si | 1.00 max | 1.00 max |
| Phosphorus, P | 0.030 max | 0.030 max |
| Sulphur, S | 0.020 max | 0.020 max |
| Iron, Fe | Balance | Balance |
Cross reference tables for the legacy BS 318S13 row show a tighter phosphorus limit of 0.025% max and do not specify nitrogen, since nitrogen control was set out in the later EN and UNS grades. Where a legacy BS specification is invoked, the stricter of the two limits is applied.
Mechanical properties
| Property | 318S13 | Grade 316 for comparison |
|---|---|---|
| 0.2% proof stress | 450 N/mm² min | approx. 205 N/mm² |
| Tensile strength | 620 N/mm² min | - |
| Elongation, A | 25 % min | - |
| Hardness | 293 HB max | - |
| PREN | approx. 35 - 36 | approx. 24 |
Corrosion resistance
318S13 resists intergranular corrosion, and its general corrosion performance is better than grade 316. Resistance to chloride stress corrosion cracking is higher than both 304 and 316, which is the property that most often decides its selection for marine and chloride bearing service.
Where higher corrosion resistance is needed than 318S13 provides, the usual step up is super duplex. See A182 F53 and A182 F55. Where formability matters more than strength, consider 904L or the 6%Mo austenitic grade A182 F44.
Forging, heat treatment and machining
Melting
318S13 is supplied EAF plus VOD melted. ESR material is available where the specification or the duty of the part requires it.
Hot forging
Hot working of 22Cr duplex is carried out in the range 950-1230 °C. Published practice for 2205 is to heat uniformly to approximately 1120-1150 °C and to stop forging before the stock falls below about 950 °C, reheating as often as needed. Hammer forging is preferred. Even heating and control of finishing temperature are more critical for duplex than for austenitic grades.
Heat treatment
318S13 forgings are solution annealed at 1020-1100 °C, then water quenched or rapidly cooled. The grade cannot be hardened by heat treatment and work hardens only. Rapid cooling through the critical range is required to suppress sigma phase and other intermetallics, which reduce both toughness and corrosion resistance.
Machining
Machinability is limited by the high strength of the grade. Cutting speeds run approximately 20% below grade 304. Use rigid setups, positive rake coated carbide and a depth of cut sufficient to get under the work hardened layer. Reduce feeds only slightly. Forming needs higher capacity equipment than austenitic grades, and cold heading requires intermediate annealing.
Welding
Most conventional processes are suitable. Autogenous welding without filler is not, because it leaves excessive ferrite. Use 2209 type consumables to restore the phase balance, keep heat input low, and apply no pre-heat and no post-weld heat treatment. Nitrogen additions to the shielding gas help maintain austenite. The low coefficient of thermal expansion results in less distortion than with austenitic stainless steel.
318S13 forged products
Seamless rolled rings
Ring rolled 318S13 with circumferential grain flow, for pressure containing parts and bearing races.
Forged flanges
A182 F51 and F60 flanges, weld necks, blinds and special bore flanges to ASME B16.5, B16.47 or drawing.
Shafts and spindles
Pump shafts, mixer shafts, eccentric shafts and turbine spindles for corrosive duty.
Round bars and blanks
Forged, rough turned or peeled bar for valve stems, fasteners and machined components.
Discs and gear blanks
Forged discs and blanks for compressors, gearboxes and power transmission.
Sleeves and bushings
Hollow forgings and bored bushings for subsea, deepwater and compressor service.
Tube sheets
Heat exchanger and separator tube sheets, drilled or blank, for chemical and desalination plant.
Valve components
Valve bodies, seat rings, blocks and stems for ball, gate, globe, check and plug valves.
Hollow and stepped forgings
Forged pipes, tubes, nozzles and manifolds as near net open-die shapes.
Typical applications
318S13 is specified in the chemical, shipbuilding, pulp and paper, mining, petrochemical, desalination and power generation industries. Forged components include pump and cooler parts, bolts, bushes, shafts and valve parts, tanks and piping for chemical tankers, desalination plant pipework, agitators and pressure vessel parts, rotors and fans, press rolls and paper machine parts, and offshore equipment handling chloride bearing media. In oil and gas it is used for wellhead and christmas tree components, manifolds, separator internals, and downhole service in moderately corrosive sour gas wells, subject to the NACE MR0175 / ISO 15156 limits that apply to the service environment.
Inspection, testing and certification
| Item | Standard or scope |
|---|---|
| Ultrasonic testing | EN 10228-4, ultrasonic testing of austenitic and austenitic-ferritic stainless steel forgings. ASTM A388 by agreement |
| Liquid penetrant | ASTM E165, EN ISO 3452 |
| Chemical analysis | Full product analysis per heat |
| Tensile and impact | Room temperature, plus low temperature Charpy on request |
| Phase balance | Metallographic ferrite content and intermetallic phase check. ASTM A923 by agreement |
| Corrosion testing | ASTM A262, ASTM G48 pitting test on request |
| Certification | EN 10204 3.1, issued by the manufacturer's own inspection department, or 3.2, countersigned by an independent third party |
For offshore and subsea packages, buyers often require the forging manufacturer to hold qualification under NORSOK M-650, with material requirements to NORSOK M-630. Send the project specification and the scope that can be met will be confirmed in writing before quotation.
Frequently asked questions
What is 318S13 steel?
318S13 is the British Standard designation for 22% chromium austenitic-ferritic duplex stainless steel. It is equivalent to UNS S31803, EN 1.4462 (X2CrNiMoN22-5-3), ASTM A182 F51 and JIS SUS 329J3L, and is sold commercially as Duplex 2205.
Is 318S13 the same as 2205 duplex?
318S13 corresponds to UNS S31803, the original 22Cr duplex grade marketed as 2205. The grade was revised in 1996 to UNS S32205, ASTM A182 F60, which narrows the chromium, molybdenum and nitrogen ranges. Most current material is dual certified to both S31803 and S32205.
What is the difference between A182 F51 and A182 F60?
F51 is the ASTM A182 forging grade for UNS S31803, the original 22Cr duplex composition. F60 is the forging grade for the revised UNS S32205 composition. They are the same alloy family. F60 restricts chromium, molybdenum and nitrogen to the upper part of the F51 range.
What are the mechanical properties of 318S13 forgings?
Solution annealed 318S13 gives a minimum 0.2% proof stress of 450 N/mm², minimum tensile strength of 620 N/mm², minimum elongation of 25% and hardness of 293 HB max. Proof stress is about twice that of grade 316.
How is 318S13 heat treated after forging?
Solution anneal at 1020-1100 °C, then water quench or cool rapidly. The grade cannot be hardened by heat treatment and work hardens only. Rapid cooling through the critical range is required to avoid sigma phase and other embrittling intermetallics.
What is the maximum service temperature?
About 300 °C. Above that, brittle micro-constituents precipitate. Below about -50 °C the material undergoes a ductile to brittle transition. Embrittlement from service exposure can be removed by a full solution anneal.
What is the PREN of 318S13 compared with 316?
Using PREN = %Cr + 3.3 x %Mo + 16 x %N, 22Cr duplex such as 318S13 gives approximately 35 to 36, against about 24 for grade 316.
Is 318S13 difficult to machine?
It is harder to machine than austenitic stainless steel because of its strength. Expect cutting speeds about 20% lower than grade 304. Use rigid setups and coated carbide, and reduce feeds only slightly. Forming needs higher capacity equipment, and cold heading requires intermediate annealing.
Which ultrasonic testing standard applies?
EN 10228-4, which covers ultrasonic testing of austenitic and austenitic-ferritic stainless steel forgings. EN 10228-3 covers ferritic and martensitic forgings and does not apply to duplex. ASTM A388 can be applied by agreement.
Can Jiangyin Jiangnan Metal forge 318S13 to my drawing?
Yes. Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, producing 318S13 rings, seamless rolled rings, flanges, shafts, bars, discs, sleeves, bushings and tube sheets to drawing. Send your drawing or size list to sales@steelforgepieces.com or call +86-189-2135-9659.
Request a quotation for 318S13 forgings
Send the drawing, or the grade, shape and finished dimensions, with quantity, the certification level required (EN 10204 3.1 or 3.2) and any project specification. You will receive a price, the proposed forging route and a lead time.
Jiangyin Jiangnan Metal Co., Ltd.
Open-Die Forging Factory
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Tel, WhatsApp, WeChat: +86-189-2135-9659
E-mail: sales@steelforgepieces.com
Related duplex and stainless forging grades
A182 F51 · A182 F53 · A182 F55 · A182 F44 · 904L · Sanicro 28 · Nitronic 50 · 17-4PH · Incoloy 825 · Inconel 625
Page maintained by the engineering department of Jiangyin Jiangnan Metal Co., Ltd. Composition, property and heat treatment data compiled from published EN 10088 and UNS S31803 grade data and from stockholder cross reference tables. Last reviewed . Values are for guidance. Order specific properties are confirmed on the EN 10204 certificate.