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Chemical compositions of AISI (ASTM/ASME) and UNS ferritic stainless steel grades

Introduction – AISI ASTM ASME and UNS

Most ASTM and ASME standards list the steel grades by their UNS (Unified Numbering system) numbers but also make reference, where appropriate to the more general AISI (American Iron and Steel Institute) grade designations. These grade numbering systems are widely used in the USA, where they originated and are recognised by most stainless steel specifiers and users.
The American Iron and Steel Institute (AISI) developed designations such as 304, 430 etc and published compositions for these in their ‘Steel Products Manual’ (1974).
These are NOT specifications, but steel grade composition ranges only.
These grades were used by the American Society Testing and Materials (ASTM) to identify grades in a wide range of standards they published for stainless products, such as sheets and plates (ASTM A240), bars (ASTM A276) and tubes (ASTM A269).
The compositions of the AISI grades were made more specific with the introduction of the ‘Unified Numbering System’, jointly established by ASTM and SAE (Society of Automotive Engineers).
This five digit number, preceded by the letter ‘S’ for most stainless steels, identified the specific variant of the grade

e.g. 430 being UNS S43000, 430F being UNS S43020

American Society of Mechanical Engineers (ASME) publish design codes and standards for pressure applications. ASME standards are generally based on the appropriate ASTM standards, but the standard numbers are preceded with the letters ‘SA’, rather than just the ‘A’ of the ASTM standards.
Where UNS grade numbers are used, these are universal, regardless of the product type or the standard in which they appear.

The AISI designations have been adopted in Japan. The AISI number is preceded with the letters SUS e.g. SUS 430. The Japanese have developed variants on some grades for certain product forms e.g. SUS 430J1L for sheet products.
The composition ranges should always be checked in the appropriate standard.

Composition tables

The tables in this article use the UNS number as their key, but also show the related AISI and SAE numbers. Where appropriate, common names for the steels are also shown.
As an alternative to scanning down the list try the ‘find’ facility on your keyboard, using the ‘Ctrl’ and ‘F’ keys together. Type in the term you are looking for in the dialog box that then appears.
The data given is not intended to replace that shown in individual standards to which reference should always be made.

Standard ferritic grades

Designation Chemical composition % by mass max unless stated
UNS No SAE No AISI No / Common Name C Si Mn P S Cr Mo Ni Others
S18200 XM-34 (18-2FM) 0.08 1.00 2.50 0.04 0.15 min 17.5/19.5 1.50/2.50
S18235 0.025 1.00 0.50 0.030 0.15/0.35 17.5/18.5 2.00/2.50 1.00 N 0.025; (C+N) 0.035; Ti 0.30/1.00
S40300 51403 403 0.15 0.50 1.00 0.040 0.030 11.5/13.0
S40500 51405 405 0.08 1.00 1.00 0.040 0.030 11.5/14.5 Al 0.10./0.30
S40800 0.08 1.00 1.00 0.045 0.045 11.5/13.0 0.50 Ti 12xC/1.10
S40900 409 This well known grade is replaced by S40910 S40920 and S40930
S40910 0.030 1.00 1.00 0.040 0.020 10.5/11.7 0.50 N 0.030; Ti: 6x(C+N)/0.50; Nb 0.17
S40920 0.030 1.00 1.00 0.040 0.020 10.5/11.7 0.50 N 0.030; Ti 0.15/0.50; Ti 8x(C+N) min Nb 0.10
S40930 0.030 1.00 1.00 0.040 0.020 10.5/11.7 0.50 N 0.030; (Ti+Nb) [0.08+8x(C+N)]/0.75; Ti 0.05 min
S40945 0.030 1.00 1.00 0.040 0.030 10.5/11.7 0.50 N 0.030; Ti 0.05/0.20; Nb 0.18/0.40
S40975 0.030 1.00 1.00 0.040 0.030 10.5/11.7 0.50/1.00 N 0.030; Ti: 6x(C+N)/0.75
S40976 0.030 1.00 1.00 0.040 0.030 10.5/11.7 0.75/1.00 N 0.040; Nb 10x(C+N)-0.80
S40977 3CR12 0.030 1.00 1.00 0.040 0.015 10.5/12.5 0.30/1.00 N 0.030
S41003 0.030 1.00 1.50 0.040 0.030 10.5/12.5 1.50
S41008 410S 0.08 1.00 1.00 0.040 0.030 11.5/13.5 0.60
S41045 0.030 1.00 1.00 0.040 0.030 12.0/13.0 0.50 N 0.030; Nb 9x(C+N)/0.60
S41050 0.04 1.00 1.00 0.040 0.030 10.5/12.5 0.60/1.10 N 0.10
S41603 0.08 1.00 1.25 006 0.15min 12.0/14.0
S42035 0.08 1.00 1.00 0.045 0.030 13.5/15.5 0.2/1.2 Ti 0.30/0.50
S43000 51430 430 0.12 1.00 1.00 0.040 0.030 16.0/18.0
S43020 51430F 430F 0.12 1.00 1.25 0.060 0.15 min 16.0/18.0 0.75
S43023 51430FSe 430FSe 0.12 1.00 1.25 0.060 0.060 16.0/18.0 Se 0.15
S43036 430Ti 0.10 1.00 1.00 0.040 0.030 16.0/19.5 0.75 Ti 5xC/0.75
S43400 51434 434 0.12 1.00 1.00 0.040 0.030 16.0/18.0 0.75/1.25
S43600 51436 436 0.12 1.00 1.00 0.040 0.030 16.0/18.0 0.75/1.25 Nb+Ta 5xC/0.80
S44200 51442 442 0.20 1.00 1.00 0.040 0.035 18.0/23.0 0.60

Special ferritic grades

Designation Chemical composition % by mass max unless stated
UNS No SAE No AISI No / Common Name C Si Mn P S Cr Mo Ni Others
S32803 Cronifer 2803Mo 0.015 0.55 0.50 0.020 0.0035 28.0/29.0 1.80/2.50 3.0/4.0 N 0.020; (C+N) 0.030; Nb 0.15/0.50
S43035 435 0.030 1.00 1.00 0.040 0.030 17.0/19.0 0.50 Ti [0.20+4(C+N)] / 1.10; Al 0.15
S43903 51439LL 439LL 0.014 1.00 1.00 0.040 0.030 17.0/19.0 0.50 Ti [0.20+4(C+N)] / 1.10; Al 0.15; N:0.04
S43932 441 0.030 1.00 1.00 0.040 0.030 17.0/19.0 0.50 N 0.030; (Ti+Nb) [0.20+4(C+N)] / 0.75; Al 0.15
S43940 0.030 1.00 1.00 0.040 0.015 17.5/18.5 Ti 0.10/0.60; Nb [0.30+(3xC)] min
S44400 444 18Cr-2Mo 0.025 1.00 1.00 0.040 0.030 17.5/19.5 1.75/2.50 1.00 N 0.035; (Ti+Nb)[0.20+4(C+N)] / 0.80
S44500 0.020 1.00 1.00 0.040 0.012 19.0/21.0 0.60 N 0.03; Cu 0.30/0.60; Nb 10x(C+N) / 0.80
S44626 XM-33 (26-1Ti) 0.06 0.75 0.75 0.040 0.020 25.0/27.0 0.75/1.50 0.50 N 0.04; Cu 0.20; Ti 0.20/1.00 Ti 7x(C+N) min
S44627 XM-27 0.010 0.40 0.40 0.020 0.020 25.0/27.0 0.75/1.50 0.50 N 0.015; Cu 0.20; Nb 0.05/0.20; (Ni+Cu) 0.50
S44635 Nu Monit (25-4-4) 0.025 0.75 1.00 0.040 0.030 24.5/26.0 3.5/4.5 3.5/4.5 N 0.035; (Ti+Nb){0.20+4(C+N)] / 0.80
S44660 Sea-cure (26-3-3) 0.030 1.00 1.00 0.040 0.030 25.0/28.0 3.0/4.0 1.0/3.5 N 0.040; (Ti+Nb)0.20 / 1.00; (Ti+Nb) [6x(C+N)] min
S44700 29-4 0.010 0.20 0.30 0.025 0.020 28.0/30.0 3.5/4.2 0.15 N 0.020; Cu 0.15; (C+N) 0.025
S44735 0.030 1.00 1.00 0.040 0.030 28.0/30.0 3.6/4.2 1.00 N 0.045; (Ti+Nb)0.20/1.00; (Ti+Nb) 6x (C+N) min
S44800 29-4-2 0.010 0.20 0.30 0.025 0.020 28.0/30.0 3.5/4.2 2.00/2.50 N 0.020; Cu 0.15; (C+N) 0.025
S46800 0.030 1.00 1.00 0.040 0.030 18.0/20.0 0.50 N 0.030; Ti 0.07/0.30; Nb 0.10/0.60; (Ti+Nb) [0.20+4(C+N)] / 0.80

Related Articles

  1. Related ferritic stainless steel grades

Related References

  1. ASTM and SAE-AMS Standards and Specifications for Stainless Steel
  2. ASTM International, West Conshohocken, PA 19428-2959, USA, 2003

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