1.3964 Forgings & Seamless Rolled Rings
X2CrNiMnMoNNb21-16-5-3

1.3964 is the EN material number for X2CrNiMnMoNNb21-16-5-3, a nitrogen-strengthened, niobium-stabilised austenitic stainless steel specified in SEW 390 for non-magnetisable applications. It contains 20.0–21.5 % chromium, 15.0–17.0 % nickel, 4.0–6.0 % manganese, 3.0–3.5 % molybdenum and 0.20–0.35 % nitrogen, with carbon held below 0.03 %. The combination gives a stable austenitic structure that stays non-magnetic after cold work, high strength without heat treatment, and good resistance to seawater and intergranular corrosion.

No. They are near-equivalents, not the same grade. 1.3964 to SEW 390 specifies 15.0–17.0 % nickel and 3.0–3.5 % molybdenum, while UNS S20910 (XM-19, Alloy 50) to ASTM A479 specifies 11.5–13.5 % nickel and 1.5–3.0 % molybdenum, allows a wider chromium range and up to 0.06 % carbon, and adds 0.10–0.30 % vanadium. Both are non-magnetic, high-strength and seawater resistant, and they are often cross-referenced, but a certificate to one does not automatically satisfy a drawing calling for the other. Jiangyin Jiangnan Metal Co., Ltd. quotes and certifies to whichever the drawing names; say which standard governs when you enquire.

No. 1.3964 is fully austenitic and designed to stay non-magnetic even after cold working. Published figures for relative permeability are µ_r 1.04 from Deutsche Edelstahlwerke for the solution-annealed condition and µ_r ≤ 1.01 from voestalpine Specialty Metals including after cold work. This is the key difference from 304 and 316, which are non-magnetic when annealed but become measurably magnetic once cold worked, because deformation transforms austenite into ferromagnetic martensite. If your design has a permeability limit, state it and the measurement method on the order so it is verified before shipment.

In the solution-annealed condition, open-die forgings to WL 1.3964-3 must reach a 0.2 % proof strength of at least 365 N/mm², a tensile strength of 700–950 N/mm², elongation A₅ of at least 35 % up to 160 mm thickness and at least 30 % above it, and ISO-V impact energy of at least 85 J at room temperature. Typical measured values are around 560 N/mm² proof strength, 890 N/mm² tensile strength, 39 % elongation and 150 J impact energy, with hardness in the 180–220 HB range. Above 160 mm ruling section the properties are agreed between purchaser and supplier.

Solution annealing at 1020–1050 °C (1868–1922 °F) followed by rapid cooling in air or water. The grade is austenitic and cannot be hardened by heat treatment. For forging, the workpiece is preheated to 950–1150 °C and worked between 900 and 1100 °C, then cooled rapidly to avoid precipitation of phases that would harm corrosion resistance and mechanical properties. At Jiangyin Jiangnan Metal Co., Ltd. the solution treatment runs in high-temperature car-bottom furnaces with a 3,500 × 1,300 × 1,100 mm working chamber.

Yes. Carbon is limited to 0.03 % and the steel is stabilised with niobium, so welding does not precipitate chromium carbides at grain boundaries and the joint remains resistant to intergranular attack in the as-welded condition. Where filler metal is needed, grades 1.3954 and 1.3984 are the usual choices. If post-weld heat treatment is unavoidable because of heavy cold deformation or a thick wall, apply the same 1020–1050 °C solution treatment with rapid cooling.

The pitting resistance equivalent number of 1.3964 is 33.1 to 38.6, calculated as Cr + 3.3 Mo + 16 N across the SEW 390 composition range. That places it well above 316L, which sits at roughly 23 to 30. One qualification matters in practice: the high manganese content that stabilises the austenite reduces pitting resistance relative to a low-manganese steel of the same PREN, so although 1.3964 resists seawater corrosion, specify an ASTM G48 pitting test where pitting is the governing mechanism.

ASTM A745/A745M or EN 10228-4, both of which cover austenitic and austenitic-ferritic stainless steel forgings. ASTM A388 and EN 10228-3 apply to ferritic and martensitic forgings and are not the correct practice for this grade, because coarse austenitic grain scatters and attenuates the ultrasonic beam and calls for different probe frequencies, angles and acceptance criteria. For the same reason, surface crack detection on 1.3964 uses liquid penetrant rather than magnetic particle inspection, since the material cannot be magnetised.

Jiangyin Jiangnan Metal Co., Ltd. forges 1.3964 at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. The works has operated since 1997 and melts its own steel, so a 1.3964 forging is traceable to its melt number rather than to a purchased billet. Product forms include seamless rolled rings, forged rings, flanges, shafts, discs, tube sheets, bars, blocks, sleeves and valve components. Minimum order is 10 kg, lead time is typically 20 to 60 days, and certification is EN 10204 3.1 as standard or 3.2 witnessed on request. Contact sales@steelforgepieces.com or +86 189 2135 9659.

Forging capacity at Jiangyin Jiangnan Metal Co., Ltd. reaches 30 tonnes on a 6,300 t press and rings roll to 6,000 mm outside diameter, but for 1.3964 the binding constraint is usually the solution-annealing furnace rather than the press. Solution treatment at 1020–1050 °C runs in high-temperature car-bottom furnaces with a working chamber of 3,500 × 1,300 × 1,100 mm, which comfortably covers rings to about 1,300 mm outside diameter and shafts to about 3,500 mm in a single charge. Larger 1.3964 pieces are reviewed case by case before quotation, so state the finished size in the enquiry.