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Austenitic Stainless Steel

Austenitic stainless steels hold 16–26 % chromium with enough nickel (or manganese and nitrogen in the 200 series) to keep a face-centred-cubic structure at room temperature, so they are non-magnetic, tough down to cryogenic temperatures and cannot be hardened by heat treatment. 304 (18 % Cr, 8 % Ni) yields about 210–290 MPa annealed and work-hardens to more than twice that; the group is roughly two thirds of all stainless made.

Popular austenitic stainless grades

Compare in the explorer
GradeYield, MPaTensile, MPaDensity, g/cm³MachinabilityWeldabilityBest for
3042505858FairExcellentThe default stainless; sheet, plate, bar, tube
304L2755857.9FairExcellentWelded sections over 5 mm without sensitizing
316L2905807.98FairExcellentChlorides, marine spray, pharma and food process
3212406207.9FairExcellentStabilized for 425–815 °C; exhaust and bellows
310S2605907.98PoorVery goodFurnace parts and radiant tubes to 1,100 °C
3015709007.88FairGoodSpring clips and formed sheet; work-hardens fastest
2013807507.8FairGoodLow-nickel trim and appliance panels

All 363 austenitic stainless grades

Choose austenitic stainless for

Tanks, enclosures, fittings, food and pharmaceutical hardware, welded assemblies that stay bare, deep-drawn sinks and housings, cryogenic vessels and furnace parts to 1,100 °C — wherever corrosion resistance, formability and weldability matter more than hardness or a magnetic response.

Look elsewhere when

The part must be hardened (410, 420 or 17-4 PH), needs to be magnetic or cheaper for trim (430), sits in immersed seawater or hot brine beyond what 316L tolerates (2205 or 254 SMO), is a turned part in volume where 303 cuts about 30 % faster, or needs twice the yield of 316 with better chloride resistance (2205).

Yield strength against max service temp, Austenitic (300 & 200 series) among every stainless steel grade

No materials in view have both of these properties.

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Austenitic stainless by application

Welded tanks and enclosures
304L and 316L sheet and plate with 308L or 316L filler — the low-carbon grades keep the heat-affected zone free of chromium carbides without a post-weld anneal.
Chloride and chemical exposure
316L for salt spray, mild acids and CIP chemistry; 317L (3–4 % Mo) when 316L pits; 316Ti where an EN drawing calls for the stabilized grade.
Heat to 1,100 °C
321 or 347 to about 800 °C, 309S to 1,000 °C, 310S to 1,100 °C in air; A286 where a bolt or turbine part also needs strength at 650 °C.
Implants and instruments
316LVM (ASTM F138) for implants; 304 and 316L for instrument bodies, trays and housings, passivated after machining.

Working with austenitic stainless

Machining
Work-hardens at the cutting edge and runs at 40–60 % of the speed of mild steel: rigid setups, sharp positive tools, steady feed, no dwelling. 304 and 316L machine alike; 321 and 310S are gummier; 303 is the answer when a turned part runs in volume.
Welding
The easiest stainless to weld — TIG or MIG with 308L for 304, 316L for 316, 347 for 321 and 347. Use the L or stabilized grade above about 5 mm; thermal expansion is about 50 % higher than carbon steel, so clamp and sequence to limit distortion, then pickle or electropolish the heat tint.
Forming
304 deep-draws, spins and bends to about 1 t with more springback than mild steel; 305 is the low work-hardening grade for severe drawing, 301 for parts that need the strength cold work gives (full-hard 301 reaches about 1,300 MPa tensile).
Finishing
Passivate after machining (ASTM A967). Mill 2B, brushed No. 4, mirror No. 8 and electropolish are standard; electropolishing also improves cleanability and fatigue. PVD adds colour and hardness; stainless is not anodized.

Other stainless steel series

Austenitic Stainless Steel — frequently asked

What is austenitic stainless?

Austenitic stainless steels hold 16–26 % chromium with enough nickel (or manganese and nitrogen in the 200 series) to keep a face-centred-cubic structure at room temperature, so they are non-magnetic, tough down to cryogenic temperatures and cannot be hardened by heat treatment. 304 (18 % Cr, 8 % Ni) yields about 210–290 MPa annealed and work-hardens to more than twice that; the group is roughly two thirds of all stainless made.

Which grade of austenitic stainless should I use?

304 unless there is a reason not to, and 304L for anything welded thicker than about 5 mm so the heat-affected zone does not sensitize. 316L adds 2–3 % molybdenum for chlorides — road salt, seawater spray, bleach, process chemicals — and is the default for marine and pharmaceutical hardware. 321 (titanium-stabilized) and 347 (niobium-stabilized) hold up at 425–815 °C where plain 304 would form chromium carbides; 309S and 310S carry 23–25 % chromium for oxidation to 1,000–1,100 °C. 301 work-hardens fastest for spring clips, 201 swaps most of the nickel for manganese as the low-cost trim grade, and 316LVM (ASTM F138) is the vacuum-remelted implant grade.

Which grade of austenitic stainless is the strongest?

1.4612 has the highest yield strength in the series at 1,450 MPa; 1.4596 follows at 1,350 MPa. Values are for each grade's default condition.

Which grade of austenitic stainless is easiest to machine?

CF16Fa (machinability very good, 72/100), then 1.4598 (68/100).

Is austenitic stainless heat-treatable?

No. These grades are strengthened by cold work and softened by annealing, not by heat treatment; the conditions are listed on each grade page.

321 or 347 for hot service?

Both are 304 stabilized against carbide sensitization — 321 with titanium, 347 with niobium — and both serve to about 800 °C. 347 keeps its stabilizer through welding (titanium burns off in the arc), so it is the choice for welded assemblies and is also the filler for both; 321 is cheaper and the usual sheet, tube and bellows grade. Above 850 °C move to 309S or 310S, where scaling rather than sensitization sets the limit.

Why is my 304 part slightly magnetic?

Cold work turns part of the austenite into strain-induced martensite, which is magnetic — heavily formed corners, rolled threads and machined surfaces of 304 or 301 attract a magnet even though the annealed sheet did not. 316L, with more nickel, stays austenitic under far more deformation; a solution anneal at about 1,050 °C restores the non-magnetic state.