Austenitic Stainless Steels

Austenitic Stainless Steels

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 Grades

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 Grades

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
394S17
AU188ZU*
1.4570
-
-
X6CRNICUS18-9-2
-

* Free machining grade: only for moderate amount of cold heading.

Austenitic Steel Grades

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
-