Materials & grades
316 / 1.4401 / SUS316 molybdenum austenitic stainless steel
Type 316 is the standard molybdenum-bearing austenitic stainless steel, with about 2% molybdenum for better resistance to chlorides than 304. It is UNS S31600 in the USA, X5CrNiMo17-12-2 (1.4401) in Europe, 316S31 in the UK, X04Cr17Ni12Mo2 in India and SUS316 in Japan.
Names by standard
What it is called in each region
| Region | System | Designation | Norma | Match |
|---|---|---|---|---|
| USA | AISI/ASTM | 316 | ASTM A240 (plate, sheet, strip); ASTM A276 (bar) | Same material |
| UNS | S31600 | — | Same material | |
| UK | BS 970-3 (1991) | 316S31Stainless grades are no longer in BS 970; new orders use EN 10088-3. The name is still used on drawings. | BS 970-3 | Equivalent |
| BS 970-3 (1991) | 316S33Companion 316-type grade listed alongside 316S31. | BS 970-3 | Closest equivalent | |
| BS 970 (1955 EN series) | EN58JSuperseded 1955 name for 316-type bar. | — | Closest equivalent | |
| EU | EN 10027-1 name | X5CrNiMo17-12-2 | EN 10088-2; EN 10088-3 | Equivalent |
| EN 10027-2 number | 1.4401 | EN 10088-2; EN 10088-3 | Equivalent | |
| EN 10027-2 number | 1.4436Higher-molybdenum variant (X3CrNiMo17-13-3) also sold as 316. | EN 10088-2; EN 10088-3 | Closest equivalent | |
| India | IS 1570 | X04Cr17Ni12Mo2 | IS 1570 (Part 5):1985 | Equivalent |
| Japan | JIS | SUS316 | JIS G 4303 (bar); JIS G 4304 / G 4305 (plate, sheet) | Equivalent |
On equivalence
- EN 1.4401 has a narrower molybdenum range (2.00–2.50%) than ASTM 316, JIS SUS316 and IS X04Cr17Ni12Mo2 (2.00–3.00%). 316 made at the top of the ASTM range may instead meet 1.4436, a higher-molybdenum EN grade.
- Nickel limits also differ: 10.00–13.00% for 1.4401 against 10.0–14.0% for ASTM, JIS and IS. Carbon is capped at 0.07% in EN and 0.08% elsewhere.
- UK: BS 970-3 listed 316S31 and 316S33 for 316-type bar, and the 1955 EN series used EN58J. Some charts also give EN58H. Stainless bar is now specified to EN 10088-3.
- 316L is the low-carbon version (C ≤0.030%): UNS S31603, 1.4404 (X2CrNiMo17-12-2), SUS316L and IS X02Cr17Ni12Mo2. It resists sensitisation during welding and is used for heavy welded sections; 316/316L dual-certified stock is common.
- 316H (UNS S31609) has 0.04–0.10% carbon for elevated-temperature strength; 316Ti is the titanium-stabilised alternative.
- Cross-reference tables are approximate comparisons, not contractual equivalents.
Chemical composition
Composition limits, mass %
| Element | 316 (S31600)USA · ASTM A240 | X5CrNiMo17-12-2 (1.4401)EU · EN 10088-2 / EN 10088-3 (heat analysis) | X04Cr17Ni12Mo2India · IS 1570 (Part 5):1985 | SUS316Japan · JIS G 4303 (bar) |
|---|---|---|---|---|
| C | ≤0.08 | ≤0.07 | ≤0.08 | ≤0.08 |
| Si | ≤0.75 | ≤1.00 | ≤1.0 | ≤1.00 |
| Mn | ≤2.00 | ≤2.00 | ≤2.0 | ≤2.00 |
| P | ≤0.045 | ≤0.045 | ≤0.045 | ≤0.045 |
| S | ≤0.030 | ≤0.015 | ≤0.030 | ≤0.030 |
| Cr | 16.0–18.0 | 16.50–18.50 | 16.0–18.0 | 16.00–18.00 |
| Ni | 10.0–14.0 | 10.00–13.00 | 10.0–14.0 | 10.00–14.00 |
| Mo | 2.00–3.00 | 2.00–2.50 | 2.0–3.0 | 2.00–3.00 |
| N | ≤0.10 | ≤0.10 | — | — |
Mechanical properties
Strength and hardness
| Condition | Tensile strength | Yield strength | Elongation | Hardness |
|---|---|---|---|---|
| AnnealedSpecified minimums, plate, sheet and strip (ASTM A240); hardness is a maximumASTM A240, via Atlas Steels 316/316L/316H grade data sheet | ≥515 MPa≥75 ksi | ≥205 MPa≥30 ksi | ≥40 % | ≤217 HB (≤95 HRB) |
| Solution annealed (+AT)Specified, bar and sections up to 160 mm, longitudinal testEN 10088-3, via thyssenkrupp Materials (UK) datasheet 1.4401 | 500–700 MPa73–102 ksi | ≥200 MPa≥29 ksi | ≥40 % | — |
| Solution annealed (+AT)Specified, hot rolled plate up to 75 mm, transverse testEN 10088-2, via thyssenkrupp Materials (UK) datasheet 1.4401 | 520–670 MPa75–97 ksi | ≥220 MPa≥32 ksi | ≥45 % | — |
| Solution treatedSpecified, bar; hardness is a maximumJIS G 4303, via Nose Stainless steel-grade reference sheet | ≥520 MPa≥75 ksi | ≥205 MPa≥30 ksi | ≥40 % | ≤187 HBW |
In practice
Behaviour, heat treatment and uses
Characteristics
- Molybdenum gives 316 better overall corrosion resistance than 304, especially against pitting and crevice corrosion in chloride environments.
- In potable water it is considered resistant to pitting at up to about 1000 mg/L chlorides at ambient temperature, falling to about 300 mg/L at 60 °C.
- It is often called marine grade but is not fully resistant to sea water. Surface staining appears in many marine settings, especially at crevices and on rough finishes.
- It is subject to stress corrosion cracking above about 60 °C.
- It cannot be hardened by heat treatment. Strength is raised only by cold work.
- Weldability is excellent by all standard fusion methods. Heavy welded sections need post-weld annealing for maximum corrosion resistance; 316L avoids this.
- Machining is harder than for carbon steel because the grade work-hardens. Improved-machinability versions of 316 bar are available.
- It is essentially non-magnetic when annealed and becomes slightly magnetic with cold work.
- Toughness remains excellent down to cryogenic temperatures. Oxidation resistance is good to about 870 °C intermittent and 925 °C continuous.
Heat treatment
- Solution annealing: 1010–1120 °C (Atlas guidance) or 1030–1110 °C (EN guidance), then cool rapidly in water or air.
- No hardening treatment exists; 316 is strengthened only by cold work.
- Avoid prolonged service or slow cooling in the 425–860 °C range where corrosion resistance matters, or use 316L or titanium-stabilised 316Ti.
- Hot forming: 1150–820 °C, then air cool.
Usos habituales
- Food processing and pharmaceutical equipment
- Laboratory equipment and chemical containers
- Boat fittings and coastal architectural panelling, railings and trim
- Offshore equipment and chemical tanker tanks and tubes
- Heat exchangers, filtration screens, threaded fasteners and springs
Stainless steels
Similar grades compared
| Grado | C % | Mn % | Cr % | Ni % | Tensile, first listed condition |
|---|---|---|---|---|---|
| 316 / 1.4401 | ≤0.08 | ≤2.00 | 16.0–18.0 | 10.0–14.0 | ≥515 MPa |
| 201 / 1.4372 | ≤0.15 | 5.50–7.50 | 16.0–18.0 | 3.5–5.5 | ≥515 MPa |
| 301 / 1.4310 | ≤0.15 | ≤2.00 | 16.0–18.0 | 6.0–8.0 | ≥515 MPa |
| 303 / 1.4305 | ≤0.15 | ≤2.0 | 17.0–19.0 | 8.0–10.0 | 650 MPa |
| 304 / 1.4301 | ≤0.08 | ≤2.00 | 18.0–20.0 | 8.0–10.5 | ≥515 MPa |
| 304L / 1.4307 | ≤0.030 | ≤2.00 | 18.0–20.0 | 8.0–12.0 | ≥485 MPa |
| 309 / 309S | ≤0.08 | ≤2.00 | 22.0–24.0 | 12.0–15.0 | ≥515 MPa |
| 310 / 310S | ≤0.08 | ≤2.00 | 24.0–26.0 | 19.0–22.0 | ≥515 MPa |
| 316L | ≤0.030 | ≤2.00 | 16.0–18.0 | 10.0–14.0 | ≥485 MPa |
| 321 | ≤0.08 | ≤2.00 | 17.0–19.0 | 9.0–12.0 | ≥515 MPa |
Composition from the US standard where one exists, otherwise the first standard listed on each grade's page. Strength conditions differ between grades; open a grade for its full table.
Preguntas resueltas
Common questions
What is the difference between 304 and 316 stainless steel?
316 contains 2–3% molybdenum and more nickel than 304. The molybdenum improves resistance to pitting and crevice corrosion in chloride environments such as coastal air, salt and process water. Mechanical properties are similar; 316 costs more.
Is 316 stainless steel the same as 1.4401?
1.4401 (X5CrNiMo17-12-2) is the European counterpart of 316, but the limits are not identical. EN 1.4401 restricts molybdenum to 2.00–2.50%, while ASTM 316 allows 2.00–3.00%. Check the certificate when a drawing calls for one standard specifically.
What is 316L stainless steel?
316L is the low-carbon version of 316, with carbon limited to 0.030%. It resists carbide precipitation during welding, so heavy welded parts keep full corrosion resistance without post-weld annealing. Its EN number is 1.4404 and its JIS name is SUS316L.
Does 316 stainless steel rust in seawater?
316 is the usual marine grade but it is not fully resistant to sea water. Brown surface staining and crevice corrosion can occur, especially at crevices and on rough finishes. Smooth finishes, regular washing and good design limit it; more highly alloyed grades are used for immersion.
Is SUS316 the same as 316?
SUS316 is the Japanese JIS name for the 316 grade. Its composition limits closely match ASTM 316, including 2.00–3.00% molybdenum, and material is often certified to both. Specified bar properties under JIS G 4303 are 205 MPa minimum proof stress and 520 MPa minimum tensile strength.
From the Corona catalog
Products listed with 316 / 1.4401
Keep reading
Related references
References
Sources
- Atlas Steels, Stainless Steel 316, 316L, 316H Grade Data Sheet (revised 27/04/2021) — ASTM A240 composition and mechanical properties, corrosion, heat treatment, welding, grade comparison.
- thyssenkrupp Materials (UK), Stainless Steel 1.4401 Material Data Sheet (11/2017) — EN composition, mechanical properties by product form, solution annealing, hot forming, welding.
- Nose Stainless, steel types, composition and mechanical properties (JIS reference sheet) — JIS G 4303 bar composition and mechanical properties for SUS316.
- Bureau of Indian Standards, IS 1570 (Part 5):1985 Schedules for wrought steels, stainless and heat-resisting steels (Public.Resource.Org copy) — Table 1 composition for X04Cr17Ni12Mo2 and X02Cr17Ni12Mo2.
- Vulcan Engineering, stainless steel bar datasheets — Related specifications: BS 970-3 316S31/316S33, BS 970 1955 EN58J, W.Nr 1.4401, JIS G 4303 SUS316, ASTM A276.
- Atlas Steels, Product Manual Section 9 (grade cross-reference) — Links 316 to EN58H and EN58J; states comparisons are approximate.
Values summarize published limits and typical data. The governing standard and the current edition control; check them before specifying.