Materials & grades
304 / 1.4301 / SUS304 austenitic stainless steel
Type 304 is the standard 18/8 austenitic stainless steel, with about 18% chromium and 8% nickel, and the most widely used stainless grade. It is UNS S30400 in the USA, X5CrNi18-10 (1.4301) in Europe, 304S31 in the UK, X04Cr19Ni9 in India and SUS304 in Japan.
Names by standard
What it is called in each region
| Region | System | Designation | Norma | Match |
|---|---|---|---|---|
| USA | AISI/ASTM | 304 | ASTM A240 (plate, sheet, strip); ASTM A276 (bar) | Same material |
| UNS | S30400 | — | Same material | |
| UK | BS 970-3 (1991) | 304S31Stainless 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) | 304S15Companion 304-type grade that some charts give instead of 304S31. | BS 970-3 | Closest equivalent | |
| BS 970 (1955 EN series) | EN58ESuperseded 1955 name commonly cross-referenced to 304; sources vary. | — | Closest equivalent | |
| EU | EN 10027-1 name | X5CrNi18-10 | EN 10088-2; EN 10088-3 | Equivalent |
| EN 10027-2 number | 1.4301 | EN 10088-2; EN 10088-3 | Equivalent | |
| DIN (legacy) | X5CrNi18 10Superseded DIN spelling of the same grade, still seen on older drawings. | DIN 17440 | Equivalent | |
| Índia | IS 1570 | X04Cr19Ni9Indian product standards such as IS 6911 (plate, sheet and strip) also cover 304; check the designation in the governing edition. | IS 1570 (Part 5):1985 | Equivalent |
| Japan | JIS | SUS304 | JIS G 4303 (bar); JIS G 4304 / G 4305 (plate, sheet) | Equivalent |
On equivalence
- 304, 1.4301, SUS304 and X04Cr19Ni9 are functionally similar but their limits differ. ASTM A240 caps silicon at 0.75%, EN 10088 at 1.00%; current ASTM A240, JIS and IS allow carbon to 0.08% and chromium to 20%, against 0.07% and 19.5% in EN 1.4301.
- ASTM made minor changes to 304 and 304L limits in 2006–07 to harmonise with ISO and European standards. Cross-reference tables remain approximate, not contractual equivalents.
- UK: BS 970-3 listed 304S15 and 304S31 for 304-type bar. Charts disagree on which to give; stainless bar is now specified to EN 10088-3.
- India: IS 1570 (Part 5):1985 uses X04Cr19Ni9. Some charts and product-standard summaries print X04Cr18Ni10 or X04Cr19Ni10; confirm against the IS edition named on the order.
- 304L is the low-carbon version (C ≤0.030%): UNS S30403, 1.4307 (X2CrNi18-9), SUS304L and IS X02Cr19Ni10. It resists sensitisation during welding and is used for heavy welded sections; 304/304L dual-certified stock is common.
- 304H (UNS S30409) has 0.04–0.10% carbon for strength at elevated temperature.
- ASTM A240 limits shown are for the current edition (304: C ≤0.08, Cr 18.0–20.0, Ni 8.0–10.5). Editions up to 2015 printed C ≤0.07, Cr 17.5–19.5 and Ni 8.0–10.5. One reading of the A240/A240M-20a text gave Ni 8.0–11.0; other current A240 listings give 8.0–10.5, which is used here. Check the edition named on your order.
- EN 10088-3:2014 gives nitrogen ≤0.10 % for 1.4301; the 2005 edition printed ≤0.11 %.
Chemical composition
Composition limits, mass %
| Element | 304 (S30400)USA · ASTM A240 | X5CrNi18-10 (1.4301)EU · EN 10088-3 (bar, rod, wire, sections) | X04Cr19Ni9Índia · IS 1570 (Part 5):1985 | SUS304Japan · 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 | ≤0.030 | ≤0.030 | ≤0.030 |
| Cr | 18.0–20.0 | 17.50–19.50 | 17.5–20.0 | 18.00–20.00 |
| Ni | 8.0–10.5 | 8.00–10.50 | 8.0–10.5 | 8.00–10.50 |
| 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 304/304L/304H grade data sheet | ≥515 MPa≥75 ksi | ≥205 MPa≥30 ksi | ≥40 % | ≤201 HB (≤92 HRB) |
| Solution annealed (+AT)Specified, bar and sections up to 160 mm, longitudinal testEN 10088-3, via thyssenkrupp Materials Services datasheet 1.4301 | 500–700 MPa73–102 ksi | ≥190 MPa≥28 ksi | ≥45 % | — |
| Solution annealed (+AT)Specified, cold rolled strip up to 8 mm, transverse testEN 10088-2, via thyssenkrupp Materials Services datasheet 1.4301 | 540–750 MPa78–109 ksi | ≥230 MPa≥33 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
- Corrosion resistance is very good in most atmospheres and many corrosive media. It is subject to pitting and crevice corrosion in warm chloride environments and to stress corrosion cracking above about 60 °C.
- In potable water it is considered resistant to pitting at up to about 200 mg/L chlorides at ambient temperature, falling to about 150 mg/L at 60 °C.
- It cannot be hardened by heat treatment. Strength is raised only by cold work.
- Weldability is excellent by all standard fusion methods, with or without filler, and no preheat is needed. Heavy welded sections may need post-weld annealing to restore full corrosion resistance; 304L avoids this.
- Formability is excellent; 304 can be deep drawn severely without intermediate annealing.
- Machining is harder than for carbon steel because the grade work-hardens. Improved-machinability versions of 304 bar are available, and 303 is the free-machining alternative.
- 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 in intermittent service and 925 °C in continuous service. Long exposure at 425–860 °C sensitises 304 and reduces later aqueous corrosion resistance.
Heat treatment
- Solution annealing: 1010–1120 °C (Atlas guidance) or 1000–1100 °C (EN guidance), then cool rapidly in water or air.
- No hardening treatment exists; 304 is strengthened only by cold work.
- Avoid prolonged service or slow cooling in the 425–860 °C range where corrosion resistance matters, or use 304L.
- Hot forming: 850–1150 °C, then air cool.
Usos típicos
- Food processing, brewing, dairy and wine equipment
- Kitchen benches, sinks, troughs and appliances
- Architectural panelling, railings and trim
- Chemical containers and heat exchangers
- Threaded fasteners, springs, woven and welded screens
Stainless steels
Similar grades compared
| Grau | C % | Mn % | Cr % | Ni % | Tensile, first listed condition |
|---|---|---|---|---|---|
| 304 / 1.4301 | ≤0.08 | ≤2.00 | 18.0–20.0 | 8.0–10.5 | ≥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 |
| 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 |
| 316 / 1.4401 | ≤0.08 | ≤2.00 | 16.0–18.0 | 10.0–14.0 | ≥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.
Perguntas respondidas
Common questions
Is SUS304 the same as 304?
SUS304 is the Japanese JIS name for the same 18/8 austenitic grade. Its limits are close to current ASTM 304: both allow up to 0.08% carbon and 18–20% chromium, while EN 1.4301 sets 0.07% carbon and 17.5–19.5% chromium. Material is often certified to both.
What is the difference between 304 and 304L?
304L limits carbon to 0.030% instead of 0.08% (0.07% in EN 1.4301). The lower carbon prevents chromium carbide formation during welding, so heavy welded parts keep their corrosion resistance without post-weld annealing. 304L has slightly lower specified strength; corrosion resistance is otherwise the same.
304 vs 316: which stainless steel should I use?
Use 304 for general indoor, food and architectural service. Choose 316 where chlorides are present, such as coastal air, de-icing salts or process water, because its 2–3% molybdenum gives better resistance to pitting and crevice corrosion. 316 costs more.
Is 304 stainless steel magnetic?
Annealed 304 is essentially non-magnetic because its structure is austenitic. Cold working, such as bending, drawing or machining, can make it slightly magnetic. This does not by itself mean the material is not 304.
What is 1.4301 stainless steel?
1.4301 is the European EN material number for X5CrNi18-10, the 304-type austenitic stainless steel. It is specified in EN 10088-2 for flat products and EN 10088-3 for bar and sections.
From the Corona catalog
Products listed with 304 / 1.4301
Keep reading
Related references
References
Sources
- Atlas Steels, Stainless Steel 304, 304L, 304H Grade Data Sheet (revised 23/04/2021) — ASTM A240 composition and mechanical properties, corrosion, heat resistance, heat treatment, welding, grade comparison.
- thyssenkrupp Materials Services, Werkstoffdatenblatt 1.4301 (X5CrNi18-10) — EN 10088 composition by product form, mechanical properties, solution annealing and hot forming, welding and magnetism notes.
- Nose Stainless, steel types, composition and mechanical properties (JIS reference sheet) — JIS G 4303 bar composition and mechanical properties for SUS304.
- 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 X04Cr19Ni9 and X02Cr19Ni10.
- Vulcan Engineering, stainless steel bar datasheets — Related specifications: BS 970-3 304S15/304S31, W.Nr 1.4301, JIS G 4303 SUS304, ASTM A276.
- West Yorkshire Steel, international stainless steel cross-reference — Gives 304S15 as the BS 970 counterpart and the DIN spelling X5CrNi1810.
Values summarize published limits and typical data. The governing standard and the current edition control; check them before specifying.