X6CrNiMoTi17-12-2 Forgings (1.4571 / AISI 316Ti / UNS S31635)

Titanium-stabilised austenitic stainless steel. Forged rings, seamless rolled rings, flanges, shafts, discs, sleeves and tube sheets, made to drawing by Jiangyin Jiangnan Metal Co., Ltd.

Published by Jiangyin Jiangnan Metal Co., Ltd., open-die forging works, Jiangyin, China Last reviewed 10 October 2026 Data basis EN 10088-1/-2/-3, EN 10222-5, EN 10250-4, ASTM A182 and A240

1. What X6CrNiMoTi17-12-2 is

X6CrNiMoTi17-12-2 belongs to the molybdenum-bearing austenitic family and is a 316-type steel with a deliberate titanium addition. Titanium is a stronger carbide former than chromium, so during welding or slow cooling through the sensitisation range it ties up carbon as titanium carbide instead of letting chromium carbides form at the grain boundaries. The chromium stays in solution and the steel resists intergranular corrosion both as delivered and as welded, which is why the grade is still specified for welded chemical and process equipment where a low-carbon L grade on its own is not accepted at elevated service temperature.

Against the unstabilised 1.4301 type, the 2.0 to 2.5 % molybdenum gives better resistance to pitting and crevice attack. The grade welds by all common processes apart from gas welding, needs no heat treatment after welding, and forges well by open-die and drop forging. The trade-offs are real: machinability is only moderate to poor because titanium carbonitrides wear tooling quickly, the surface will not take a high polish, and the steel can show a slight magnetic response after heat treatment.

2. Equivalent designations and governing standards

Standards the grade appears in

For forged products the two documents that matter are EN 10222-5, steel forgings for pressure purposes covering martensitic, austenitic and austenitic-ferritic stainless steels, and EN 10250-4, open-die steel forgings for general engineering purposes. The grade is also listed in EN 10088-1 for the list of stainless steels, EN 10088-2 for sheet, plate and strip, EN 10088-3 for semi-finished products, bars, rods, wire, sections and bright products, EN 10028-7 for flat products for pressure purposes, EN 10272 for bars for pressure purposes, EN 10216-5 and EN 10217-7 for seamless and welded tubes, and EN 10253-3 and EN 10253-4 for butt-welding fittings. On the American side the matching documents are ASTM A182 for forged flanges, fittings and valve parts and ASTM A276 or A479 for bars.

3. Chemical composition

Sulphur: EN 10088-2 limits S to 0.015 % for 1.4571, while some data sheets issued to EN 10088-3 quote 0.030 %. If a project needs dual EN and ASTM certification, state the controlling specification on the enquiry so the heat can be selected to suit.

4. Mechanical properties

The grade is delivered in the solution annealed condition. The European and American acceptance values are listed side by side below, because a drawing calling out X6CrNiMoTi17-12-2 is judged against the EN limits while one calling out 316Ti is judged against the ASTM limits.

Heavy open-die forgings and rolled rings are tested in the section thickness agreed on the order. For rings with a wall above 160 mm, acceptance values are agreed case by case in line with EN 10222-5 and EN 10250-4.

5. Physical properties

6. Forging, heat treatment and machining

Melting route

We melt X6CrNiMoTi17-12-2 by EAF plus VOD, with an additional ESR remelt where the application calls for better cleanliness, tighter segregation control or a demanding ultrasonic acceptance class. Ingot or billet size is matched to the finished forging so that a sound reduction ratio is reached through the full section.

Forging parameters

Heat the stock to 1150 to 1180 C and forge within the band 1180 C down to 950 C, then cool in water. General hot forming is carried out between 1200 C and 900 C. Both open-die forging and drop forging work in this grade. Finishing below 950 C should be avoided, because the work hardening rate climbs steeply and the risk of surface tearing rises with it.

Heat treatment

The standard condition is solution annealing at 1020 to 1120 C followed by rapid cooling in water or air. The grade cannot be hardened by heat treatment; strength is raised only by cold work. Stress relieving of machined or welded assemblies is normally carried out between 200 and 400 C with air cooling, which does not harm the stabilised structure. No heat treatment is needed after welding, and where a filler is used, 1.4430 is a common recommendation.

Machining

Machinability is moderate to poor next to unstabilised Cr-Ni-Mo grades, because titanium carbonitrides form during cutting and wear the tool edge. This is not a free-machining grade and it does not suit aggressive high-speed machining schedules. Rigid set-ups, sharp positive-rake carbide tooling, generous coolant and moderate surface speeds with a solid depth of cut give the best tool life.

7. Corrosion behaviour

With a PREN of 23.1 to 26.7, X6CrNiMoTi17-12-2 performs well in natural media and in environments with low chloride and salt content, and it resists intergranular corrosion both as delivered and as welded. It handles organic acids such as formic, acetic, lactic, oleic, benzoic and tartaric acid, sulphuric acid at low to medium concentration, nitric and phosphoric acid at room and low temperature, boric acid, atmospheres carrying sulphur dioxide, many hydroxides, and a wide range of salts including nitrates, borates, bromides and chlorides at moderate concentration.

It is not suitable for seawater or high-salt service, where pitting is likely, nor for hydrochloric or hydrofluoric acid. Where chloride pitting resistance is the controlling requirement, look at the higher-alloyed grades we also forge, such as 904L, A182-F44, duplex F51 or super duplex F53.

8. Forged shapes we produce in X6CrNiMoTi17-12-2

Everything below is made to the customer drawing or to finished dimensions, as open-die forgings or seamless rolled rings, with the machining allowance agreed on the order.

9. Typical applications

• Chemical and petrochemical plant. Reactor and vessel flanges, heat exchanger tube sheets, nozzles, piping components and chemical transport tanks.
• Pressure vessel and pipeline construction. Forged flanges and bodies to EN 10222-5 where resistance to intergranular corrosion after welding is required.
• Pulp and paper. Digester parts, liquor tank fittings, paper machine rolls and shafts.
• Petroleum refining. Catalytic recovery systems, recuperators and exchanger components.
• Oil and gas, offshore and onshore. Bushings, sleeves and discs for production systems, industrial air compressors, power generators and nitrogen generators, within the chloride limits of the grade.
• Food, brewing and pharmaceutical production. Shafts and bars for equipment handling organic acids, plus laboratory and medical equipment parts.
• Power transmission. Rings, spindles, bars and gear blanks for turbines, gas compressors and gearboxes.
• Shipbuilding, automotive and architecture. Apparatus engineering parts, exhaust and housing components, railings and facade fixings.

10. Testing, inspection and certification

Chemical analysis is reported per heat. Mechanical testing covering tensile strength, elongation, hardness and, where specified, impact energy is carried out on test blanks heat treated together with the forgings. Ultrasonic testing follows EN 10228-3, SEP 1921 or ASTM A388 to the class stated on the order. Liquid penetrant examination to ASTM E165, intergranular corrosion testing to ASTM A262 practice E and positive material identification are available on request. Documents are issued as an EN 10204 3.1 mill certificate, or EN 10204 3.2 counter-signed by a nominated third-party inspection body such as SGS, BV, TUV or Lloyd's.

11. Frequently asked questions

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