X2CrNiMoN17-13-3 (EN 1.4429 / 316LN) Open-Die Forgings

Seamless rolled rings, flanges, shafts, discs, sleeves, bushings, tube sheets and forged bars, produced to drawing by Jiangyin Jiangnan Metal Co., Ltd.

Chemical composition of EN 1.4429

The 0.015 % sulphur ceiling applies to long products under EN 10088-3. The general EN 10088-1 listing allows up to 0.030 % S. State the product standard on your enquiry and the heat is aimed at the tighter limit where needed.

Calculated pitting resistance equivalent

Applying PREN = %Cr + 3.3 × %Mo + 16 × %N to the limits above gives roughly 26.7 at the lean end and 31.9 at the rich end. The figure is arithmetic from the specification rather than a test result. Where service conditions sit close to the limit, critical pitting temperature testing is the better basis for selection.

Mechanical properties

Two points worth knowing before you write a purchase specification. First, EN 10088-3 sets no upper limit on Rp0.2 for this grade, so figures such as "Rp0.2 max 320 N/mm²" that circulate on trade sites are not from the standard. Second, stockist datasheets for finished bar quote Rm 580 N/mm² min, Rp0.2 290 N/mm² min, A5 35 % min and 220 HB max, because values depend on product form, section size and delivery condition. Tell us the governing standard and the section and the certificate is issued against that.

Equivalent and related grades

These grades are equivalent, not interchangeable. EN 1.4429 calls for N 0.12 to 0.22 % and Mo 2.5 to 3.0 %, whereas UNS S31653 allows N 0.10 to 0.16 % and Mo 2.0 to 3.0 %. A heat certified to one will not automatically pass the other. If you need dual certification, say so at enquiry stage so the heat analysis is aimed at the overlap.

Standards applying to forgings in this grade

For forged product the governing documents are EN 10250-4, open-die steel forgings for general engineering purposes in stainless steels, and EN 10222-5, steel forgings for pressure purposes in martensitic, austenitic and austenitic-ferritic stainless steels. Composition and bar properties come from EN 10088-1 and EN 10088-3. Bars for pressure purposes fall under EN 10272, flat pressure-vessel product under EN 10028-7, seamless tube under EN 10216-5 and EN 10297-2, and fasteners with specified elevated or low temperature properties under EN 10269. On an ASME or ASTM route, forged flanges, fittings and valve parts are ordered to ASTM A182 F316LN.

Heat treatment, forging and machining

Solution annealing

Solution anneal at approximately 1030 to 1110 °C with cooling in water or air according to section size. Mill practice also calls for solution annealing in the 1050 to 1150 °C range whenever the final forming temperature has fallen below 950 °C. Fast cooling through the carbide precipitation range is what holds chromium carbides in solution, so letting a heavy forging cool slowly undoes the benefit of the low carbon specification. The grade cannot be hardened by heat treatment.

Hot forging

The nitrogen that gives this steel its strength also raises hot flow stress, so 1.4429 asks for more press capacity than 316L at the same reduction and for a long, even soak before the first blow. Finishing too cold invites surface tearing. Start and finish temperatures are recorded per heat on the forging route card.

Machining

Machinability is broadly in line with 304 and 316L and below that of free-machining or martensitic grades such as 410. The real constraint is work hardening. Rigid setups, sharp positive-rake tooling, heavier feeds with fewer passes and no dwelling in the cut are what keep tool life reasonable.

Welding

Weldable by the usual austenitic processes. With carbon at 0.030 % max, post-weld solution annealing is normally unnecessary to restore intergranular corrosion resistance. Filler is usually a matching 316LN or 316L type chosen against the service medium.

Why this grade gets specified over 316L

Against standard 316 and 316L, 1.4429 brings better resistance to chlorides, seawater and acids, better resistance to crevice and intergranular attack, and higher strength at elevated temperature. The higher proof strength often allows a thinner wall or a lighter flange at the same design pressure, which is usually where the material premium is paid back. The grade also keeps good toughness at low temperature, which is why it turns up in liquefied gas and cryogenic equipment.

Forged products in X2CrNiMoN17-13-3

Where it is used

Forgings in this grade go into chemical and petrochemical plant such as columns, towers, reactors and preheaters; into heat exchangers, condensers and evaporators, where tube sheets and shell flanges carry both chloride and thermal load; into pharmaceutical, pulp and paper, rubber, plastics and textile equipment; into offshore and subsea production hardware, wellheads and manifolds; into cryogenic and liquefied gas tankage; and into nuclear and power generation auxiliary systems where low carbon and controlled nitrogen are mandated. In bar form the grade is also used for surgical instruments and orthopaedic implant stock, which says something about the cleanliness achievable in it.

Manufacturing and quality route

Melting is by electric arc furnace with VOD refining, with ESR remelting available where cleanliness or segregation limits demand it. Forgings are supplied solution annealed, and pickled or machined all over when specified. Ultrasonic examination is to EN 10228-3, SEP 1921 or ASTM A388, with dye penetrant to ASTM E165 on request. Certification is EN 10204 3.1, or 3.2 with third party witness by Lloyd's, DNV, BV, TUV, SGS or your own inspector. Intergranular corrosion testing to EN ISO 3651-2 or ASTM A262 Practice E can be added to the order.

Common questions

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Standards referenced on this page

EN 10088-1 and EN 10088-3, composition and mechanical properties for steel number 1.4429. EN 10250-4, open-die steel forgings for general engineering purposes, stainless steels. EN 10222-5, steel forgings for pressure purposes, stainless steels. EN 10272, stainless steel bars for pressure purposes. EN 10028-7, flat products for pressure purposes. ASTM A182/A182M Grade F316LN, UNS S31653, forged flanges, fittings, valves and parts.

Page updated 9 October 2026. Values shown are specification limits or published datasheet figures and are given for guidance. Order-specific properties are confirmed on the material test certificate.