{"id":3653,"date":"2026-09-16T11:14:27","date_gmt":"2026-09-16T08:14:27","guid":{"rendered":"https:\/\/www.defencemetal.com\/index.php\/en\/aisi-321\/"},"modified":"2026-09-25T16:30:17","modified_gmt":"2026-09-25T13:30:17","slug":"aisi-321","status":"publish","type":"page","link":"https:\/\/www.defencemetal.com\/index.php\/en\/aisi-321\/","title":{"rendered":"AISI 321 \/ (1.4541)"},"content":{"rendered":"

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AISI 321 \/ (1.4541) \/ UNS S32100 \/ AMS 5510 \/ AMS 5557<\/h1>\n
DEFENCE METAL<\/span><\/p>\n
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AISI 321<\/div>\n
UNS S32100 \u00b7 W.Nr. 1.4541 \u00b7 X6CrNiTi18-10 \u00b7 17.0-19.0% Cr \u2013 9.0-12.0% Ni \u2013 C \u2264 0.08% \u2013 Ti 5\u00d7(C+N) minimum to 0.70% maximum \u2013 balance Fe. The silicon ceiling CHANGES WITH THE SPECIFICATION: 0.75% in ASTM A240; 1.00% in ASTM A276, A182 and EN 1.4541. The EN 1.4541 band is: C \u2264 0.08%, Si \u2264 1.00%, Mn \u2264 2.00%, Cr 17.00-19.00%, Ni 9.00-12.00%, Ti from 5\u00d7C to 0.70% (the EN multiplier is 5\u00d7C, the ASTM one is 5\u00d7(C+N)). It is an austenitic stainless steel: NOT PRECIPITATION HARDENABLE, it cannot be hardened by heat treatment; strength is raised only by cold work. The titanium is NOT a hardener, it is A CARBON BINDER.<\/div>\n
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Not to be confused with<\/div>\n

AISI 316Ti<\/a><\/div>\n<\/div>\n

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For what<\/div>\n
Bought for parts that are fabricated by welding and then run for long periods in the 425-850 \u00b0C band: exhaust manifolds and expansion bellows, furnace parts, heat exchangers, hot process piping, refinery equipment.<\/div>\n<\/div>\n
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Forms<\/div>\n
Round bar \u00b7 flat bar \u00b7 plate \u00b7 sheet \u00b7 strip \u00b7 seamless and welded pipe \u00b7 seamless and welded tube \u00b7 forging \u00b7 ring \u00b7 flange \u00b7 wire \u00b7 welding wire. All forms are supplied to order.<\/div>\n<\/div>\n
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Standards<\/div>\n
AMS: 5510 (sheet, strip, plate) \u00b7 5645 (bar, wire, forging) \u00b7 5570 (seamless tube) \u00b7 5576 (welded tube) \u00b7 5557 (seamless\/welded tube) \u00b7 5559 (thin-wall welded tube). ASTM: A240 \/ SA-240 (plate, sheet, strip) \u00b7 A276 (bars and shapes) \u00b7 A479 \/ SA-479 (bar for boilers and pressure vessels) \u00b7 A312 \/ SA-312 (seamless and welded pipe) \u00b7 A213 \/ SA-213 (seamless boiler and heat-exchanger tube) \u00b7 A249 \/ SA-249 (welded tube) \u00b7 A182 \/ SA-182 (F321 forged flanges, fittings and valve parts) \u00b7 A314 (billets and bars for forging) \u00b7 A473 (forgings) \u00b7 A580 (wire) \u00b7 A484 (general requirements). EN: 1.4541 \u00b7 10088-2 \u00b7 10088-3 \u00b7 10028-7 \u00b7 10216-5 \u00b7 10217-7 \u00b7 10222-5.
321 DOES have AMS numbers; in that respect it differs from grades such as 316Ti and 314. The ones confirmed by four independent sources are AMS 5510 (sheet\/strip\/plate), 5645 (bar\/wire\/forging) and 5570 (seamless tube).<\/span><\/div>\n<\/div>\n
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Advantage<\/div>\n
The stress-relief anneal may be carried out INSIDE the sensitization band. ATI states that 321 may be stress relief annealed within the carbide precipitation range of 427 to 816 \u00b0C (800 to 1500 \u00b0F) without any danger of subsequent intergranular corrosion;<\/div>\n<\/div>\n
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Welding<\/div>\n
FILLER METAL: ER347 \/ E347 (niobium stabilized). The 321 chemistry is not used in covered electrodes; Hobart Brothers gives the reason plainly \u2014 ‘recovery of titanium across the arc of covered electrodes is poor’.<\/div>\n<\/div>\n
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Limits<\/div>\n
1) THE LIMIT OF TITANIUM STABILIZATION: the protection depends on the ratio of titanium to carbon. The ASTM specifications require Ti \u2265 5\u00d7(C+N); below that ratio free carbon remains and the stabilization is incomplete.<\/div>\n<\/div>\n
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Compiled from manufacturer data sheets \u00b7 confirm against the current specification before ordering<\/div>\n<\/div>\n<\/div>\n

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