304 vs 316 Stainless Steel: Complete Comparison for Engineers and Buyers

Published: Apr 25, 202613 min readBy Li Wei

Li Wei

Senior Metallurgical Engineer · TISCO Stainless Steel

MSc MetallurgyASM International16 yrs nickel alloys

Reviewed by

Chen Yufan

Materials Application Engineer · TISCO Stainless Steel

BSc Materials Eng.AWS-CWI12 yrs duplex/super duplex

304 vs 316 stainless steel comparison — austenitic 18/8 chromium-nickel grades, with and without molybdenum.

304 and 316 are the two most-specified stainless steels on Earth. Together they cover roughly 80% of all stainless tonnage produced annually. The price gap is 25-35%, the corrosion gap is real but narrow, and yet the wrong choice keeps showing up in failed kitchen sinks, rust-streaked handrails and corroded heat- exchanger tubes worldwide. This article gives you the data to never make that mistake.

Skip to the verdict for the bottom line, or to the application matrix if you already know your service.

30-second verdict

Use 304 by default. Step up to 316 only when the service environment contains chlorides — saltwater, road salt, chlorinated cleaning, brine, swimming pools, coastal atmosphere — or when the media is dilute reducing acid that 304 cannot handle. For everything else, 304 performs identically while saving 25-35% on the steel cost.

Rule of thumb

If chlorides exceed ~50 ppm in continuous contact, or if the part lives within 5 km of the ocean, specify 316. Otherwise specify 304.

Chemistry side-by-side

Element (wt %)	304 (UNS S30400)	316 (UNS S31600)
Chromium (Cr)	18.0 – 20.0	16.0 – 18.0
Nickel (Ni)	8.0 – 10.5	10.0 – 14.0
Molybdenum (Mo)	—	2.0 – 3.0
Carbon (C, std)	≤ 0.08	≤ 0.08
Carbon (L, low-C)	≤ 0.030	≤ 0.030
Manganese (Mn)	≤ 2.00	≤ 2.00
Silicon (Si)	≤ 0.75	≤ 0.75
Phosphorus (P)	≤ 0.045	≤ 0.045
Sulfur (S)	≤ 0.030	≤ 0.030
Nitrogen (N)	≤ 0.10	≤ 0.10
PREN (typical)	~19	~25

The whole story is in one element: molybdenum. 316 has 2-3% Mo; 304 has none. Mo stabilises the chromium oxide passive film against attack by chloride ions, raising the pitting resistance equivalent number (PREN) from ~19 to ~25. That single change shifts the chloride threshold of safe service upward by roughly 3-5×.

Corrosion: where 316 wins

Environment	304	316
Indoor, dry air	Excellent	Excellent (overspec)
Outdoor urban atmosphere (low Cl⁻)	Good	Excellent
Outdoor coastal atmosphere	Tea-staining within 2-5 yrs	Stays bright with normal cleaning
Fresh water, < 200 ppm Cl⁻	Good	Good (overspec)
Brackish water (200-1000 ppm Cl⁻)	Pits within months	Acceptable below 50 °C
Seawater (~19,000 ppm Cl⁻)	Heavy pitting + crevice	Marginal — needs CP, short-term only
Dilute HNO₃ (oxidising)	Excellent	Excellent
Dilute H₂SO₄ (reducing)	Marginal	Better but still limited
HCl (any concentration)	Fails	Fails
NaOH, dilute & warm	Excellent	Excellent
Critical pitting temperature in 6% FeCl₃ (G48 A)	≈ 0 °C	≈ 15 °C

The biggest mistake in selecting 304 is underestimating coastal salt aerosol. Even 5-10 km from the ocean, salt deposits on metal surfaces concentrate during dry-wet cycles to many times the bulk-air value. 304 panels in coastal cities consistently tea-stain within years.

Mechanical & physical properties

Property (annealed sheet, room temp)	304	316
Yield strength 0.2% (min)	205 MPa / 30 ksi	205 MPa / 30 ksi
Tensile strength (min)	515 MPa / 75 ksi	515 MPa / 75 ksi
Elongation in 50 mm (min)	40%	40%
Hardness, Brinell (max)	201 HB	217 HB
Density	8.00 g/cm³	8.00 g/cm³
Modulus of elasticity	193 GPa	193 GPa
Coefficient of thermal expansion (0-100 °C)	17.2 × 10⁻⁶/°C	16.0 × 10⁻⁶/°C
Thermal conductivity (100 °C)	16.2 W/m·K	16.3 W/m·K
Maximum service temp. (continuous, oxidising)	~870 °C	~925 °C

Mechanical properties are practically identical. The molybdenum in 316 mildly improves elevated-temperature creep strength but does not change the room- temperature tensile or yield. If you switch from 304 to 316 for mechanical reasons alone, you are paying 25-35% more for nothing.

Magnetism, weldability, finish

Magnetism: Both are non-magnetic in the solution-annealed state and become weakly magnetic after cold-working. A magnet test cannot reliably distinguish 304 from 316 — XRF or wet chemistry are the proper tests.

Weldability: Both weld easily by GTAW, GMAW, SMAW, plasma and SAW with matching filler (ER308L for 304, ER316L for 316). For welded service, always specify the L-variant to prevent sensitisation.

Finishes: Both come in the same surface finishes — 2B, BA, No. 4 (brushed), No. 8 (mirror), and various textured patterns. 316 is slightly easier to maintain a bright finish on in coastal locations because it tea-stains less.

9 application scenarios mapped to a grade

Application	Pick	Why
Indoor commercial kitchen sink, dry storage	304	Non-chloride; cost wins
Restaurant fryer, outdoor BBQ smoker	304	Hot but non-chloride
Architectural cladding, urban inland building	304	PM2.5 + city air; PREN 19 sufficient
Architectural cladding, coastal city < 5 km from sea	316	Salt aerosol concentrates on the surface
Brewery fermenter, wine tank	304	CIP with caustic, no chloride; cost wins
Pickle / fermented foods tank, soy sauce line	316	NaCl content drives pitting risk
Swimming-pool ladders, ceiling beams above pool	316	Chloramine atmosphere; well documented failures of 304
Cryogenic LNG tank inner shell	304L	Austenite stability + cost
Pharmaceutical CIP loop with bleach	316L	NaOCl adds Cl⁻; L-grade for weld

Cost & lead time

For 2 mm × 1219 mm × 2438 mm cold-rolled, 2B-finish sheet FOB China, Q2 2026 ranges:

Form	304 (USD/kg)	316 (USD/kg)	Premium
Sheet 2B, 2 mm	1.95 – 2.30	2.55 – 3.05	+30-32%
Plate, 10 mm hot-rolled	2.10 – 2.50	2.85 – 3.40	+35-37%
Coil, 1 mm 2B	1.85 – 2.20	2.50 – 3.00	+33-36%
Pipe seamless, 50 mm OD sch 40	3.20 – 3.80	4.30 – 5.00	+30-32%

Stock availability is excellent for both grades worldwide. Custom widths and thicknesses over 60 mm typically pull from a 6-10 week mill run for 316; slightly faster for 304 because of broader stock distribution.

Selection flowchart

Figure 1. 304 vs 316 selection flowchart. Always re-check the actual chloride concentration and surface temperature before final specification.

For more on stainless steel grades, see our stainless steel sheet and plate range, stainless steel pipe and tube, and our companion blog post on duplex vs super duplex when 316 is no longer enough. For independent reference data, Outokumpu's stainless data sheets and worldstainless.org are the gold standards.

Frequently Asked Questions

Is 316 always better than 304?

No. 316 is better in chloride environments — saltwater, swimming pools, coastal atmospheres, food brining lines, marine fasteners. In dry indoor or non-chloride applications (architectural panels, kitchen equipment for fresh food, dairy lines, decorative trim), 304 performs identically and costs 25-35% less. Always pick 304 first and only step up to 316 when chloride exposure is genuine.

Are 304 and 316 magnetic?

In the fully solution-annealed condition, both are non-magnetic (austenitic). However, cold-working — drawing, bending, machining, deep drawing — can transform some austenite to martensite at the surface, giving the material weak ferromagnetic response. Welds and heat-affected zones in thick sections may also show magnetism. A magnet test is therefore not a reliable way to distinguish 304 from 316.

Is 316 better for food contact than 304?

Both 304 and 316 are food-grade per FDA 21 CFR 175 and NSF/ANSI 51. The choice depends on what the food is. For dry foods, dairy, baking, juices: 304 is standard and cheaper. For high-chloride foods (brine pickles, fish processing, soy sauce), CIP cycles with hot caustic + chloride, or any saltwater contact: 316 prevents pitting. Surgical-grade implants use the higher-purity 316L variant (S31673) per ASTM F138.

Why does 316 cost more than 304?

Because 316 contains 2-3% molybdenum, and Mo is among the most expensive alloying elements (~3-5× the LME nickel price). 316 also typically has 0.5-1% more nickel. The premium runs 25-35% on plate and sheet, sometimes higher on small-diameter pipe where mill yield is lower. The premium fluctuates with LME Mo and Ni prices week to week.

Should I use 304L or 316L instead of 304/316?

For welded service, almost always yes. The 'L' (low-carbon) variants have ≤ 0.030% C and resist sensitisation — chromium carbide precipitation at 425-870 °C that depletes Cr near grain boundaries and causes intergranular corrosion. 304L and 316L cost 2-5% more than the standard grades but eliminate the need for solution annealing after welding. For non-welded service (machined parts, fasteners), the regular grades are fine.

Can I weld 304 to 316?

Yes — austenitic stainless welds well to other austenitic grades. Use ER308L filler for joining 304 to 304, ER316L for 316 to 316, and ER309L for dissimilar 304-to-316 joints (or you can use ER316L if both sides are L-grades). Heat input ≤ 1.5 kJ/mm; inter-pass temp ≤ 175 °C; solid argon backing on root passes for corrosion-critical service.

Which grade for outdoor handrails in a coastal city?

316. Even at 5-10 km from the coast, salt aerosol settles on surfaces and concentrates during dry-wet cycles to a much higher chloride than the bulk air suggests. 304 in coastal atmospheres typically tea-stains within 2-5 years and pits within 8-12 years. 316 stays bright with normal cleaning. For very high salt exposure (within 1 km of the coast), super austenitic 6-Mo or duplex 2205 are even better.

Can 304 be used in seawater?

Not for permanent immersion. 304 will pit and crevice-corrode under gaskets, deposits and biofouling within months. 316 is acceptable for short-term and lightly-flowing seawater up to ~25 °C with cathodic protection but will eventually crevice-corrode in stagnant zones. For real seawater service use super austenitic (e.g. 254 SMO), super duplex 2507, or nickel alloys like Monel 400.

Are 304 and 316 stronger than mild steel?

In yield strength, 304/316 (~205 MPa min) are roughly equal to mild structural steel (S235JR at 235 MPa). In tensile and ductility they are similar to slightly higher. The advantage of austenitic stainless is corrosion resistance, hygienic surface and toughness at cryogenic temperatures, not strength. For load-bearing structures where weight matters, duplex 2205 (yield 450 MPa) is roughly twice as strong.

References

[1]ASTM A240 — Standard Specification for Cr and Cr-Ni Stainless Steel Plate, Sheet, and Strip — ASTM International
[2]ASTM A276 — Standard Specification for Stainless Steel Bars and Shapes — ASTM International
[3]ASTM A312 — Standard Specification for Seamless and Welded Austenitic Stainless Steel Pipes — ASTM International
[4]FDA 21 CFR 175 — Indirect food additives: adhesives and components of coatings (food contact) — U.S. Food & Drug Administration
[5]NSF / ANSI 51 — Food equipment materials — NSF International
[6]ASTM F138 — Surgical implants - Wrought 18Cr-14Ni-2.5Mo (UNS S31673) — ASTM International
[7]Outokumpu — Stainless Steel Grade Datasheet 304/304L — Outokumpu
[8]ISSF — International Stainless Steel Forum: 304 vs 316 — International Stainless Steel Forum
[9]PREN — Pitting Resistance Equivalent Number on Wikipedia — Wikipedia
[10]ASM Handbook Volume 13B — Corrosion: Materials — ASM International
[11]Sandmeyer Steel Co. — 304 vs 316 stainless steel buyer's guide — Sandmeyer Steel
[12]ASTM A380 — Cleaning, Descaling and Passivation of Stainless Steel — ASTM International