Stainless Steel grades

Nitrogen-alloyed work-hardening austenitic — AISI 301LN. Lower Ni (6-8%) than 304 makes it metastable: cold work transforms austenite to martensite → UTS up to 1400 MPa in full-hard condition. N addition compensates low C for corrosion and strength. Used for rail car bodies, springs, structural parts requiring high strength-to-weight ratio, and architectural cladding.

Austenitic CrNiMo stainless — AISI 316 variant with higher Mo (2.5-3.0%) and Ni (10.5-13.0%). Better pitting resistance than standard 316 (1.4401) due to higher Mo minimum. C max 0.05% (not L-grade, so slightly higher strength than 316L). Used for chemical plant, textile dyeing equipment, and applications requiring guaranteed higher Mo than 316 minimum.

Austenitic Cr-Ni stainless with higher Ni (11-13%) than 304 (8-10.5%) — AISI 305. The higher Ni content lowers work-hardening rate, making it ideal for severe cold forming and deep drawing operations where 304 would crack. Same corrosion resistance as 304. Used for deep-drawn sinks, pots/pans, complex stampings, and cold-headed fasteners where minimum work-hardening is needed.

THE most widely used stainless steel worldwide — the original "18/8" austenitic (V2A). Good corrosion resistance in natural environments (water, humidity, weak acids). Non-magnetic when annealed. NOT resistant to intergranular corrosion after welding — use 1.4307 (304L) or 1.4541 (321) for welded service. PREN 17.5-21.1 — not suitable for chloride/seawater. Used everywhere: kitchen equipment, food processing, architecture, chemical tanks, automotive, medical devices.

Niobium-stabilized austenitic stainless with Mo — 316+Nb. Nb stabilization prevents sensitization (like 347) PLUS Mo gives pitting resistance (like 316). Best of both worlds for high-temperature welded chemical plant. Used for welded pressure vessels, heat exchangers, and piping operating at 400-800°C in mildly corrosive environments.

Titanium-stabilized austenitic Cr-Ni-Mo steel — AISI 316Ti. THE German standard industrial stainless (known as "V4A"). Ti prevents Cr-carbide precipitation at 450-850°C giving intergranular corrosion resistance after welding. Better high-temp stability than 316L (up to 550°C). PREN 23-27. Used extensively in chemical/pharmaceutical plants, pressure vessels, food processing, apparatus construction, and shipbuilding.

Niobium-stabilized austenitic stainless — European equivalent of AISI 347. Nb (10×C min) binds carbon to prevent Cr-carbide precipitation during welding or service at 400-800°C ("sensitization"). Same base composition as 304 but immune to intergranular corrosion after thermal cycling. Used for welded constructions in chemical plant, nuclear reactor internals, exhaust manifolds, and any 18/10 austenitic application with repeated heat exposure.

Titanium-stabilized austenitic stainless — AISI 321. Ti (5×C min) prevents Cr-carbide sensitization during welding or service at 400-800°C. Same approach as Nb-stabilized 347 (1.4550) but with Ti instead. Better creep resistance than 304/304L at elevated temperature. Used for exhaust manifolds, aircraft exhaust systems, expansion bellows, and high-temperature chemical plant (to ~800°C).

THE free-cutting austenitic stainless — AISI 303. Sulfur 0.15-0.35% for short-breaking chips and excellent machinability. Not weldable (hot cracking risk from S). Reduced corrosion resistance vs 304 due to sulfide inclusions. Used for high-volume CNC screw machine production of fittings, shafts, bushings, valves, and any turned stainless part where machining cost dominates.