X2CrNiMo17-12-3 (1.4432) Forged Bars, Rings and Discs
Low carbon 3 % molybdenum austenitic stainless steel. EN 1.4432, AISI 316L, UNS S31603.
X2CrNiMo17-12-3 is an austenitic stainless steel with low carbon and a raised molybdenum content. Its EN material number is 1.4432. The composition limits are 0.030 % carbon maximum, 16.5 to 18.5 % chromium, 10.5 to 13.0 % nickel and 2.5 to 3.0 % molybdenum. That molybdenum range is the top half of the 316L band, which puts the pitting resistance equivalent number (PREN) at roughly 26 to 29 against 24 to 26 for ordinary 1.4404. Carbon held at 0.030 % keeps the grade free of chromium carbide precipitation after welding, so it does not need a post-weld anneal to stay corrosion resistant.
Jiangyin Jiangnan Metal Co., Ltd. forges this grade to order at No. 1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin, Jiangsu, China. Shapes made in 1.4432 are round bar and shaft, hollow bar and sleeve, seamless rolled ring, disc, block and flanged shapes. Parts ship solution annealed (+AT) with EN 10204 certification. Email sales@steelforgepieces.com or call 0086-189-2135-9659.
- EN name
- X2CrNiMo17-12-3
- EN material no.
- 1.4432
- US equivalent
- AISI 316L / UNS S31603
- Microstructure
- Austenitic, non-magnetic
- Molybdenum
- 2.5 to 3.0 %
- PREN typical
- 26 to 29
- Density
- 8.0 g/cm³
- Min. service temp.
- -196 °C
- Delivery condition
- +AT solution annealed
- Forms forged here
- Bar, ring, disc, hollow
On this page: definition, chemical composition, mechanical properties, physical properties, equivalent grades, corrosion resistance and PREN, 1.4432 against 1.4404 and 1.4435, forging and heat treatment, sizes we forge, testing and certification, applications, FAQ, request a quote.
What is X2CrNiMo17-12-3?
X2CrNiMo17-12-3 is the EN 10088 name for material number 1.4432. The name is built from the composition. X marks a high alloy steel, 2 stands for 0.02 % nominal carbon, and 17, 12 and 3 are the nominal chromium, nickel and molybdenum percentages.
EN 10088 lists three low carbon 316L type grades that differ mainly in molybdenum and nickel. 1.4404 (X2CrNiMo17-12-2) runs 2.0 to 2.5 % Mo. 1.4432 runs 2.5 to 3.0 % Mo at the same chromium level. 1.4435 (X2CrNiMo18-14-3) has the same 3 % Mo with higher chromium and nickel. All three can be certified to AISI 316L and UNS S31603, which is why 1.4432 is often ordered as 316L with 2.5 % Mo minimum.
Buyers move to 1.4432 when a chloride service is too aggressive for a plain 1.4404 heat but does not justify a 6 % Mo superaustenitic such as 254 SMO or a duplex such as 1.4462.
Key characteristics
- Carbon capped at 0.030 % prevents chromium carbide precipitation at grain boundaries during welding, so no post-weld anneal is needed for corrosion service.
- Molybdenum at 2.5 to 3.0 % puts the PREN in the 26 to 29 band.
- Austenitic and non-magnetic as annealed. Heavy cold work can raise the permeability slightly.
- Tough down to -196 °C with no ductile to brittle transition.
- Cannot be hardened by heat treatment. Strength is raised only by cold work, giving the +C condition.
- Welds by all common processes. Usual fillers are ER316L and E316L-16, or ER317L to match the molybdenum.
Chemical composition of X2CrNiMo17-12-3 (1.4432)
The cast analysis limits below are taken from EN 10088-1 for material number 1.4432. Values are mass percent, a single figure is a maximum, and iron is the balance.
| Element | Carbon C |
Silicon Si |
Manganese Mn |
Phosphorus P |
Sulphur S |
Chromium Cr |
Nickel Ni |
Molybdenum Mo |
Nitrogen N |
Iron Fe |
|---|---|---|---|---|---|---|---|---|---|---|
| Minimum | - | - | - | - | - | 16.50 | 10.50 | 2.50 | - | bal. |
| Maximum | 0.030 | 1.00 | 2.00 | 0.045 | 0.015 | 18.50 | 13.00 | 3.00 | 0.11 | bal. |
Controlled sulphur, worth settling before you order. EN 10088 allows the sulphur range to be narrowed to suit a downstream property, and the three windows do not agree with each other:
- Machinability: 0.015 to 0.030 % S recommended and permitted.
- Weldability: 0.008 to 0.030 % S recommended and permitted.
- Polishability and high purity surfaces: 0.015 % S max recommended.
State the governing requirement on the purchase order. Elements not listed in Table 1 must not be added on purpose without the purchaser's agreement, other than for finishing the cast.
Source: EN 10088-1:2023, Stainless steels, List of stainless steels. Limits are reproduced here for reference and the standard itself governs.
Mechanical properties
Values apply to solution annealed material in the sizes stated. EN 10088-3 uses +A for annealed, +AT for solution annealed and +AT+C for solution annealed then cold worked. Forged sections above the bright bar range are agreed at order and tested to EN ISO 6892-1.
| Property | Condition | Value (MPa) | Value (ksi) |
|---|---|---|---|
| Tensile strength Rm | +A annealed | 490 to 700 | 71 to 102 |
| +AT solution annealed | 490 to 690 | 71 to 100 | |
| +AT+C cold worked | 750 to 780 | 109 to 113 | |
| 0.2 % proof strength Rp0.2 | +A annealed | 190 to 240 min | 28 to 35 |
| +AT solution annealed | 190 min | 28 min |
| Property | Orientation or temperature | Condition | Value |
|---|---|---|---|
| Elongation at fracture A | - | +A | 40 to 45 % min |
| Longitudinal | +AT | 40 % min | |
| Reduction of area Z | dia. 2 to 50 mm | +AT | 63 to 68 % |
| Impact energy KV, Charpy V | Longitudinal, +20 °C | +A | 100 J min |
| Transverse, +20 °C | +A | 60 J min | |
| Transverse, -196 °C | +A | 60 J min | |
| Brinell hardness | - | +A | 215 HBW max |
| - | +AT | 200 HBW max |
Source: EN 10088-3:2023, technical delivery conditions for semi-finished products, bars, rods, wire, sections and bright products. Reduction of area and cold worked figures relate to the 2 to 50 mm nominal diameter range. Properties of heavy forged sections are established by test on each heat and section size.
Physical properties
| Property | Value | Unit |
|---|---|---|
| Density | 8.0 | g/cm³ (0.289 lb/in³) |
| Modulus of elasticity at 20 °C | 200 | GPa (29 x 10&sup6; psi) |
| Thermal conductivity at 20 °C | 15 | W/(m·K) |
| Specific heat capacity at 20 °C | 500 | J/(kg·K) |
| Electrical resistivity at 20 °C | 0.75 | Ω·mm²/m |
| Mean coefficient of thermal expansion, 20 to 100 °C | 16.0 | 10-6 K-1 |
| Mean coefficient of thermal expansion, 20 to 200 °C | 16.5 | 10-6 K-1 |
| Melting range, approximate | 1370 to 1400 | °C |
| Magnetisable | No | austenitic, annealed condition |
Typical values for the austenitic Cr-Ni-Mo group. They are design data for reference and not guaranteed acceptance values.
Equivalent and cross-reference grades
X2CrNiMo17-12-3 appears under other names in most standard systems. The table lists the closest counterparts. These are near equivalents, not identical specifications. Composition bands, test requirements and delivery conditions differ between standards, so dual certification has to be checked against the actual heat analysis.
| Standard system | Designation | Notes |
|---|---|---|
| EN 10088, Europe | X2CrNiMo17-12-3, 1.4432 | Primary designation |
| UNS, USA | S31603 | Shared with 316L. 1.4432 sits at the high Mo end |
| AISI / ASTM | 316L | ASTM A276 and A479 bar, A182 F316L forged flanges and fittings |
| ASME | SA-182 F316L, SA-479 316L | Pressure vessel and piping service |
| DIN, Germany, withdrawn | X2CrNiMo17133, 1.4432 | Superseded by EN 10088 |
| AFNOR, France | Z3CND17-12-03 | Nearest equivalent |
| BS, UK, withdrawn | 316S13 | Nearest equivalent |
| SS, Sweden | 2353 | Nearest equivalent |
| JIS, Japan | SUS 316L | Mo 2.00 to 3.00 %, overlaps 1.4432 |
| GB/T, China | 022Cr17Ni12Mo2, old 00Cr17Ni14Mo2 | Nearest equivalent. Specify 2.5 % Mo min |
| GOST, Russia | 03Ch17N14M3 | Nearest equivalent |
| ISO | ISO 15510 X2CrNiMo17-12-3 | Same designation adopted |
Cross-reference compiled by Jiangyin Jiangnan Metal Co., Ltd. Check equivalence against the mill certificate before substituting a grade in a qualified design.
Corrosion resistance and PREN
PREN is the usual first check on chloride pitting resistance:
PREN = %Cr + 3.3 x %Mo + 16 x %N
At the bottom of the EN 10088 limits, 16.5 Cr with 2.5 Mo and no nitrogen credit, 1.4432 gives about 24.8. A mid range heat at 17.5 % Cr, 2.8 % Mo and 0.05 % N gives about 27.5. A heat at the top of every band reaches about 30. Plain 1.4404 heats usually fall between 24 and 26, 1.4462 duplex sits near 34 and 254 SMO is above 42.
Corrosion behaviour in service
- Intergranular corrosion: resistant in the delivery condition and in the sensitised condition, verified to EN ISO 3651-2 or ASTM A262 Practice E. This is what the 0.030 % carbon ceiling buys.
- Pitting and crevice corrosion: better than 1.4404 in chloride bearing media, and the critical pitting temperature rises with molybdenum content.
- Reducing acids: good resistance to dilute sulphuric, phosphoric and organic acids. The molybdenum addition is what separates this family from 304L.
- Chloride stress corrosion cracking: like all standard austenitics, susceptible above roughly 60 °C in chloride solutions under tensile stress. Where SCC governs, go to a duplex grade such as 1.4462 / F51 or a high nickel alloy rather than a higher moly austenitic.
- Seawater: suitable for intermittent and flowing service. Not recommended for stagnant warm seawater, where crevice attack starts.
- Sigma phase embrittlement: avoid long exposure between about 550 °C and 900 °C, which also costs corrosion resistance.
Temperature limits. The grade must not be applied at a metal temperature below -196 °C. At the top end, corrosion service designs are normally capped near 400 to 425 °C. Higher temperatures are governed by the applicable design code rather than by the material standard.
Choosing between 1.4432, 1.4404 and 1.4435
All three EN grades certify as 316L, and buyers often receive one when they specified another. What separates them is molybdenum content, nickel content and delta ferrite control.
| Feature | 1.4404 X2CrNiMo17-12-2 |
1.4432 X2CrNiMo17-12-3 |
1.4435 X2CrNiMo18-14-3 |
|---|---|---|---|
| Carbon, max % | 0.030 | 0.030 | 0.030 |
| Chromium % | 16.5 to 18.5 | 16.5 to 18.5 | 17.0 to 19.0 |
| Nickel % | 10.0 to 13.0 | 10.5 to 13.0 | 12.5 to 15.0 |
| Molybdenum % | 2.00 to 2.50 | 2.50 to 3.00 | 2.50 to 3.00 |
| PREN, typical | 24 to 26 | 26 to 29 | 27 to 30 |
| Delta ferrite | Not controlled | Not controlled | Low, typically under 0.5 % for pharma |
| Relative cost | Lowest | Moderate | Highest of the three |
| Specify it when | General purpose 316L service at lowest cost | Chloride pitting margin is needed without moving to duplex | Pharmaceutical and high purity work needing low ferrite and electropolished surfaces |
1.4432 is the right call when the corrosion case needs 3 % molybdenum but the cleanliness and ferrite limits of 1.4435 are not part of the specification. Where a drawing says only 316L, put the minimum molybdenum on the purchase order so that the heat which gets melted meets the design intent.
Forging, heat treatment and machining
Open-die forging practice
- Pre-heat and soak: heat uniformly to 1150 to 1200 °C and soak through section. Austenitic grades conduct heat poorly, so soak time rather than furnace temperature governs.
- Finishing temperature: do not finish below about 900 °C. Working below that risks cracking and leaves residual stress that annealing alone will not remove.
- Reduction: a forging ratio of at least 3:1 to 4:1 from the ingot or billet breaks down the cast structure and closes centre porosity.
- Cooling: do not air cool slowly from forging heat through the carbide and sigma range. Quench, or go straight to solution annealing.
Heat treatment
X2CrNiMo17-12-3 cannot be hardened by heat treatment. The only heat treatment applied is solution annealing at 1020 to 1120 °C followed by rapid cooling, water quenched for heavy sections and forced air or water for thin ones. Rapid cooling through 850 to 450 °C is what restores full corrosion resistance. Stress relief below 450 °C can be applied where distortion has to be controlled. Stress relief in the 550 to 900 °C band is not allowed for corrosion service.
Welding
Weldable by TIG, MIG, SMAW, SAW and plasma without pre-heat. Recommended fillers are ER316L and E316L for matching strength, or ER317L where matching the 3 % molybdenum matters. Keep interpass temperature below about 150 °C. Because carbon is capped at 0.030 %, post-weld solution annealing is not required for corrosion resistance at normal thicknesses.
Machining
It machines like other austenitic stainless steels and work hardens quickly. Use rigid setups, positive rake, sharp tooling, heavy positive feeds and plenty of coolant, and do not let the tool dwell. For machining intensive parts, order to the controlled sulphur window of 0.015 to 0.030 % noted above.
X2CrNiMo17-12-3 product forms and sizes we forge
Jiangyin Jiangnan Metal Co., Ltd. forges X2CrNiMo17-12-3 to customer drawings and to standard stock shapes. Parts are supplied rough machined or finish machined as required, in the solution annealed condition.
| Product form | Size range | Typical use |
|---|---|---|
| Forged round bar and shaft | dia. 80 to 1200 mm, up to 8000 mm long | Pump and valve shafts, stems, machined components |
| Square, rectangular and flat bar | Thickness 60 to 600 mm, width up to 1000 mm | Machined blocks, die bases, structural pieces |
| Seamless rolled ring | OD 200 to 4000 mm, height up to 1000 mm | Flanges, bearing races, tower and vessel rings |
| Mandrel forged ring | OD up to 2500 mm | Heavy wall rings, ring gear blanks |
| Hollow bar, sleeve, bush and cylinder | OD 150 to 1500 mm, ID from 80 mm | Bushings, liners, casings, hydraulic cylinders |
| Disc, block and plate | Diameter to 2500 mm, thickness to 800 mm | Tube sheets, blind flanges, closures, hubs |
| Step shaft and flanged shape | To drawing | Near net shape components, housings |
| Single piece weight | 5 kg to 30000 kg | - |
Also supplied in the same grade: forged flanges and fittings to ASTM A182 F316L, tube sheets, valve bodies and bonnets, and rough machined blanks with stock allowance to your machining drawing.
Testing, inspection and documentation
The following tests and documents are available for X2CrNiMo17-12-3 forgings, carried out in house or through accredited third party laboratories, and are specified at order:
- Chemical analysis, spectrometric, sampling to EN ISO 14284, heat and product analysis.
- Tensile test to EN ISO 6892-1 or ASTM A370 at room temperature.
- Impact test, Charpy V to EN ISO 148-1, including cryogenic temperatures to -196 °C.
- Brinell hardness to EN ISO 6506-1.
- Intergranular corrosion test to EN ISO 3651-2 or ASTM A262 Practice E.
- Ultrasonic testing to EN 10228-3 or ASTM A388, acceptance class agreed at order.
- Liquid penetrant testing to ASTM E165 for surface indications.
- Positive material identification, portable XRF on each piece where specified.
- Ferrite measurement where a maximum delta ferrite level is required.
- Grain size and micrographic examination to ASTM E112.
- EN 10204 type 3.1 mill certificate as standard. Type 3.2 with a third party inspection body such as TUV, SGS, BV or Lloyd's on request.
- Marking and traceability: heat number, grade and order number hard stamped or paint marked on every piece.
Typical applications of X2CrNiMo17-12-3
The grade is specified where chloride bearing or mildly acidic media meet a requirement for a weldable, tough, fully austenitic steel:
- Chemical and petrochemical processing: reactor internals, valve and pump components, heat exchanger tube sheets, agitator shafts.
- Offshore and marine: topside piping components, seawater handling hardware, fasteners and shafting in splash zone equipment.
- Seawater desalination: pump casings, flanges and valve bodies in RO and MSF plant.
- Pulp and paper: bleaching plant equipment exposed to chloride and chlorine dioxide.
- Flue gas desulphurisation: scrubber internals and ductwork components.
- Food, beverage and brewing: vessel and pipework components in salt bearing process streams.
- Pharmaceutical and fine chemicals where 3 % Mo is required but the delta ferrite control of 1.4435 is not.
- Cryogenic equipment: LNG and industrial gas components down to -196 °C.
- Textile dyeing and tanning: vessels and shafting exposed to chloride liquors.
Frequently asked questions
Is X2CrNiMo17-12-3 the same as 316L?
Close, but not identical. 1.4432 sits inside the AISI 316L and UNS S31603 limits and is normally dual certified as 316L. The difference is molybdenum. 1.4432 is held to 2.5 to 3.0 %, while 316L allows 2.0 to 3.0 %. Every 1.4432 heat qualifies as 316L, but not every 316L heat qualifies as 1.4432.
What is the material number for X2CrNiMo17-12-3?
The EN material number is 1.4432. The same number was used in the older German DIN system, and the designation X2CrNiMo17-12-3 is also adopted in ISO 15510.
What is the difference between 1.4432 and 1.4404?
Molybdenum content. 1.4404 (X2CrNiMo17-12-2) carries 2.0 to 2.5 % Mo. 1.4432 (X2CrNiMo17-12-3) carries 2.5 to 3.0 % Mo at the same chromium level. That takes the typical PREN from about 24 to 26 up to about 26 to 29, which means better chloride pitting and crevice resistance. Carbon, and therefore weldability, is the same at 0.030 % max.
What is the difference between 1.4432 and 1.4435?
Both carry 2.5 to 3.0 % Mo. 1.4435 (X2CrNiMo18-14-3) adds higher chromium at 17.0 to 19.0 % and higher nickel at 12.5 to 15.0 %, and is normally supplied with controlled low delta ferrite for pharmaceutical and high purity service. 1.4432 gives close to the same corrosion performance at lower cost when the ferrite and surface finish controls of 1.4435 are not required.
What is the PREN of X2CrNiMo17-12-3?
Using PREN = %Cr + 3.3 x %Mo + 16 x %N, the minimum from the EN 10088 composition limits is about 24.8. A typical commercial heat gives about 27.5, and a heat at the top of every band reaches roughly 30.
Can X2CrNiMo17-12-3 be hardened by heat treatment?
No. It is fully austenitic and does not respond to quench and temper hardening. The only heat treatment applied is solution annealing at 1020 to 1120 °C with rapid cooling. Strength is raised only by cold working, which gives the +AT+C condition at 750 to 780 MPa tensile strength.
Is X2CrNiMo17-12-3 magnetic?
No, not in the solution annealed delivery condition, because the structure is fully austenitic. Heavy cold work or machining can induce a little deformation martensite and a weak magnetic response at the worked surface. Where non-magnetic performance is a design requirement, put a maximum permeability on the order and it will be tested.
Does X2CrNiMo17-12-3 need post-weld heat treatment?
Not for corrosion resistance. The 0.030 % maximum carbon prevents chromium carbide precipitation in the heat affected zone, so the grade resists intergranular attack both as delivered and in the sensitised condition. Post-weld solution annealing is applied only where a design code, or a distortion or residual stress requirement, calls for it.
What temperature range can X2CrNiMo17-12-3 be used in?
The material standard states it must not be applied below -196 °C. Down to that temperature it holds 60 J transverse Charpy toughness with no ductile to brittle transition. At elevated temperature, corrosion service designs are normally limited to about 400 to 425 °C, and long exposure between roughly 550 °C and 900 °C has to be avoided because of sigma phase formation.
What forged shapes and sizes do you supply in X2CrNiMo17-12-3?
Jiangyin Jiangnan Metal Co., Ltd. forges X2CrNiMo17-12-3 as round bars and shafts, square, rectangular and flat bars, seamless rolled rings, mandrel forged rings, hollow bars, sleeves, bushes and cylinders, and discs, blocks and plates, in single piece weights from a few kilograms up to 30 tonnes. Full size ranges are in Table 7.
What certification is supplied with the forgings?
EN 10204 type 3.1 mill test certificates are supplied as standard, covering heat analysis, mechanical test results, heat treatment record and dimensional report. Type 3.2 certification witnessed by a third party inspection body is available on request, as are intergranular corrosion testing, ultrasonic testing, PMI and ferrite measurement.
What is the minimum order quantity and lead time?
Open-die forgings are made to order, so there is no fixed minimum quantity and single pieces are accepted. Lead time depends on raw material availability, section size and testing scope. Send your drawing or specification to sales@steelforgepieces.com for a confirmed delivery date with the quotation.
Request a quotation for X2CrNiMo17-12-3 forgings
Send a drawing, a sketch with dimensions, or simply the shape, size and quantity. Technical enquiries are answered within one working day.
Include if you can: grade and any dual certification required, for example 1.4432 / 316L / A182 F316L; product form and finished dimensions; quantity; delivery condition, +AT is standard; machining allowance or finish machined to drawing; NDT and testing scope; certificate type, EN 10204 3.1 or 3.2; required delivery date and destination port.
Jiangyin Jiangnan Metal Co., Ltd.
Open-Die Forging Factory
No. 1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Phone, WhatsApp and WeChat: 0086-189-2135-9659
Email: sales@steelforgepieces.com
Data sources. Composition limits are from EN 10088-1:2023. Mechanical properties are from EN 10088-3:2023. Physical properties are typical values for the austenitic Cr-Ni-Mo group. Forging, heat treatment and product form information comes from the works practice of Jiangyin Jiangnan Metal Co., Ltd.
Figures on this page are given for reference. The governing standard and the mill certificate for the delivered heat take precedence. A plain text version of this page is available at X2CrNiMo17-12-3.md.