The most common austenitic alloys are iron-chromium-nickel steels and are frequently referred to as 300 series stainless. The best known austenitic Stainless Steel grades are 304/L & 316/L with other well-known grades such as 321 and 310. These grades contain minimum 16% chromium and 6% nickel commonly referred as 18/8 stainless (grade 304). Austenitic grades are generally preferred for their ease of fabrication resulting from a stable metallurgical microstructure at all temperatures combined with good corrosion resistance, mechanical and physical properties.
The addition of molybdenum to a steel containing 18% chromium and 8% nickel improves corrosion resistance and increases significantly the high temperature strength. Grade 316/L is the most common example of this.
Included is the high alloys or “Super Austenitic” with increased chromium and nickel such as 904/L & 310/L containing up to 26% chromium and 22% nickel. Ideal for high temperature use with excellent corrosion resistance to strong acids and chlorides.
Characteristics of Austenitic Stainless Steels:
- Non-Magnetic.
- Excellent ductility.
- Good strength and scaling resistance at high temperatures(310 to 1100 Degrees Celsius)
- Cold working to increase hardness.
- Low temperature applications, cryogenic applications.
- Cannot be hardened by heat treatment.
- Weldable using all standard procedures and equipment.
Grade and Typical application:
304 – General purpose with good corrosion properties, used for architectural, food processing and domestic industries.
304L – A version of 304 with lower carbon and no requirement for post weld annealing.
310 – A high temperature grade for use in furnace parts.
316 – Used for higher corrosion resistance e.g. marine applications.
316L – A version of 316 with lower carbon and is immune from sensitisation.
321 – Titanium stabilised and suitable for heat resisting applications up to 800°C.
Welding
Special chemical balance for welding.
| Grade | EN # | UNS # | EN Name | AWS Class. |
|---|---|---|---|---|
| AISL/EL2 | 1.4316 | S30883 | X2CRNI19-9 | ER 308L |
| AISL/EL | 1.4316 | S30888 | X2CRNI19-9 | ER 308LSI |
| APFRS | 1.4833 | S30908 | X12CRNI23-13/X7CRNI23-14 | ER 309S |
| APML/EL | 1.4430 | S31683 | X2CRNIM019-12 | ER 316L |
| APML/EL2 | 1.4430 | S31688 | X2CRNIM019-12 | ER 316LSI |
Cold Heading
Copper is added to improve the austenitic structure and make the steel less prone to cold work hardening.
| Grade | EN # | AISI # | UNS # | EN Name | BS # |
|---|---|---|---|---|---|
| AISRU/1 | 1.4567 | – | – | X3CRMICU18-9-4 | 394S17 |
| AISRU/2 | – | 304CU | S30430 | – | 394S17 |
| AISRU | 1.4567 | 306CU | S30430 | X3CRNICU18-9-4 | – |
| AISRUH | 1.4567 | 304CU | S30430 | X3CRNICU18-9-4 | 394S17 |
| AISRUB | 1.4560 | – | – | X3CRNICU19-9-2 | – |
| APMRU | 1.4578 | 316CU | – | X3CRNICUM017-11-3-2 | 396S17 |
| AU188ZU* | 1.4570 | – | – | X6CRNICUS18-9-2 | – |
* Free machining grade: only for moderate amount of cold heading.
| Grade | EN # | AISI # | UNS # | EN Name | BS # |
|---|---|---|---|---|---|
| AIM/1 | – | 201 | S20100 | – | – |
| AIMR | – | XM-28 | S24100 | – | – |
| AIP | 1.4303 | 305 | S30500 | X4CRNI18-12/ X5CRNI18-12 |
– |
| AIP/DE | – | – | – | – | 347S31/ 347S20 |
| AISC | 1.4550/ 1.4546 |
347/ 347H |
834700/ 834709 |
X6CRNINB18-10/ X5CRNINB18-10 |
347831/ 347820 |
| AISH | 1.4948 | 304H | S30409 | X6CRNI18-10/ X6CRNI18-11 |
– |
| AISH1 | 1.4948 | 304H | S30409 | X6CRNI18-10/ X6CRNI18-11 |
– |
| AISH2 | – | 304H | S30409 | – | – |
| AISL | 1.4301/ 1.4307/ 1.4304 |
304/ 304L |
S30400/ S30403 |
X-5CRNI18·10/ X2CRNI18-9 |
304S15/ 304S31 |
| AISL/DE | 1.4306 | – | – | X2CRNI19-11 | 304S11 |
| AISLN | 1.4311 | 304LN | S30453 | X2CRNIN18-10 | – |
| AISN | – | 304HN | S30452 | – | – |
| AIST | 1.4541 | 321 | S32100 | X6CRNITI18-10 | 321S31 |
| AISTH | 1.4878/ 1.4544 |
321H | S32109 | X8CRNITI18-10 | – |
| AMS | – | 317 | S31700 | – | – |
| AMSL | – | 317L | S31703 | – | – |
| AMSL/DE | 1.4438 | – | – | X2CRNIM018-15-4 | – |
| AMSL/DE2 | 1.4439 | – | – | X3CRNIM0N17-13-5 | – |
| APFIS | 1.4845 | 310/310S | S31000/ S31008 |
X8CRNI25-21/ X12CRNI25-21 |
310S31 |
| APFI/SI | 1.4841 | 314 | S31400 | X15CRNISI25-21/ X15CRNISI25-20 |
314S25 |
| APFR/SI | 1.4828 | – | – | X15CRNISI20-12 | – |
| APFR | 1.4833 | 309 | S30900 | X12CRNI23-13/ X7CRNI23-14 |
– |
| APFRS | – | 309S | S30908 | – | – |
| APM/DE2 | 1.4432/ 1.4436 |
– | – | X2CRNIM017-12-3/ X5CRNIM017-13-3 |
316S33/ 316S14 |
| APM/UK2 | – | – | – | – | 316S19 |
| APMC | – | 316CB | S31640 | – | – |
| APMC/DE | 1.4580 | – | – | X10CRNIMONB18-10 | – |
| APMH | – | 316H | S31609 | – | – |
| APML | 1.4401/ 1.4404 |
316/316L | S31600/ S31603 |
X5CRNIM017-12-2/ X2CRNI17-12-2 |
316S14 |
| APMLD2 | 1 .4435/ 1 .4437 |
– | – | X2CRNIM018-14-3/ X6CRNIM018-12 |
316S13/ 316S14/ 316S33 |
| APMLN | 1.4429 | – | – | X2CRNIMON17-13-3 | – |
| APMLN/DE | 1.4406 | 316N/ 316LN |
S31651/ S31653 |
X2CRNIMON17-11 -2 | – |
| APML/FR | – | – | – | – | 316S31/ 316S14 |
| APMT | – | 316TI | S31635 | – | – |
| APMT/DE | 1.4571 | – | – | X6CRNIMOTI17-12-2 | – |
| APMZ/UK | 1.4427 | – | – | X12CRNIM0S18-11 | – |
| AU177 | 1.4310 | 301 | S30100 | X12CRNI17-7 | – |
| AU188 | 1.4310/ 1.4300/ 1.4324 |
302 | S30200 | X10CRNI18-8/ X12CRNI18-8 |
302S31/ 301S22 |
| AU188Z | 1.4305 | 303 | S30300 | X8CRN1S18-9 | 303S31 |
| AV203 | – | XM-1 | S30300 | – | – |
| NTR50 | – | XM-19 | S20910 | – | – |
| NTR60 | – | – | S21800 | – | – |
| V2111N | 1.4835 | F45 | S30815 | X9CRNISINCE21-11-2 | – |
| V2018MN | 1.4547 | F44 | S31254 | X1CRNIM0CUN20-18-7 | – |