# Steel grades

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Classification system

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**Steel grades** are grades used to classify various [steels](/source/Steel) by their [composition](/source/Chemical_composition) and physical properties. Steel grades have been developed by a number of [standards organizations](/source/Standards_organizations).

## Steel grades standards by country

- For alloys in general (including steel), [unified numbering system](/source/Unified_numbering_system) (UNS) of [ASTM International](/source/ASTM_International) and the [Society of Automotive Engineers](/source/Society_of_Automotive_Engineers) (SAE).

- American steel grades : AISI/[SAE steel grades](/source/SAE_steel_grades) standard

- [British Standards](/source/British_Standards)

- [International Organization for Standardization](/source/International_Organization_for_Standardization) [ISO/TS 4949:2016](https://www.iso.org/standard/67751.html)

- [European standards](/source/European_Committee_for_Standardization) – EN 10027

- Japanese steel grades : [Japanese Industrial Standards](/source/Japanese_Industrial_Standards) (JIS) standard and [NK](/source/Nippon_Kaiji_Kyokai) standard

- Germany steel grades : [DIN](/source/Deutsches_Institut_f%C3%BCr_Normung) standard

- China steel grades : [GB](/source/National_Standards_of_the_People's_Republic_of_China) standard

- Czech steel grades : [ČSN](/source/Czech_technical_standard) standard

- Russia steel grades : [GOST](/source/GOST) standard

- Spain steel grades : [UNE](/source/AENOR) standard

- France steel grades : [AFNOR](/source/AFNOR) standard

- Italy steel grades : [UNI](/source/Ente_Nazionale_Italiano_di_Unificazione) standard

- Sweden steel grades : [SIS](/source/Swedish_Institute_for_Standards) standard

- Norway steel grades : [DNV](/source/DNV_GL) standard

Note that an increasing number of national European standards (DIN, AFNOR, UNE, UNI, etc.) and UK standards are being withdrawn and replaced by European Standards (EN). This task is carried out by the [Comité Européen de Normalisation](/source/European_Committee_for_Standardization) (CEN) (European Committee for Standardization).

## European standard steel grades

EN 10027-1 steel grade designation system.

European standard steel grade names fall into two categories:[1]

1. Steel specified by purpose of use and mechanical properties.

1. Steel specified by chemical composition.

The inclusion of a letter 'G' before the code indicates the steel is specified in the form of a casting.

### Category 1: Steel specified by purpose of use and mechanical properties

Basic grade designations for category 1 steels consist of a single letter (designating application) then a number signifying the mechanical property (often yield strength) dictated in the standard for that application designation. For some application designations another letter is included before the property value, this number is used to indicate any special requirements or conditions. These additional letters and values depend entirely on the application of the steel and are specified in the standard and far too numerous to mention here.

The next set of 3 digits gives the steel's minimum yield strength. So S355 has a minimum yield strength of 355 MPa for the smallest thickness range covered by the relevant standard – i.e. EN10025.[2]

Below is a table indicating the most common application codes.

Application symbol Meaning Mechanical Property Details S Structural steel Minimum Yield Strength P Steel for pressure lines and vessels Minimum Yield Strength L Steel for pipe and tube Minimum Yield Strength E Engineering steels Minimum Yield Strength B Steel for reinforced concrete Characteristic Yield Case R Steel for rail use Minimum Yield Case H High Tensile Strength Flat products Minimum Yield Case If followed by T then the given mechanical property is minimum tensile strength D Flat Products for Cold Forming Followed by C, D or X and two numbers characterising steel T Tinmill Products Nominal Yield Case M Electrical Steel Number = 100 × specific loss in W/kg Number = 100 × nom thick in mm Letter for type of product (A, K, P or S[3])

#### Additional symbols

In addition to the above category codes there are symbols that can be added to the grade code to identify any additional compositional requirements, delivery conditions, mechanical properties, &c. These values depend solely on the type/application code given in the first part of the code and are so numerous as to be impossible to indicate here. Additional symbols are separated from the main code by the plus sign (+).

The most common additional symbols are the impact and temperature codes for structural steels, category 1 - Sxxx.

Impact Resistance Temperature Impact code Testing strength Temperature code Testing temperature J 27 J R Room temperature K 40 J 0 0 °C L 60 J 2 -20 °C 3 -30 °C 4 -40 °C 5 -50 °C 6 -60 °C

Example : S355J2

Delivery condition codes are also relatively common, the most common being:

Code Condition A Annealed QT Quenched and tempered N Normalised SR Stress relieved C Cold worked U Untreated G Deoxidated

Example : S355J2+N

#### Electrical steel

Electrical steel type of product letters (bold are most recent version 2016):

Code Maximum specific loss expressed for magnetic induction Type of product A 1.5 T @50 Hz non oriented D (formerly B) " non-alloy semi-finished (not finally annealed) E " alloy semi-finished (not finally annealed) K (=D+E) " non-alloy and alloy electrical steel sheet/strip in the semi-processed state N " for normal grain oriented products P 1.7 T @50 Hz high permeability grain oriented S " conventional grain oriented

#### Standard per steel name

According to EN 10027-1

Application Mechanical property additional symbol Standard S 235 JR EN 10025-2 355 JR EN 10025-2 J0 EN 10025-2 J2 EN 10025-2 K2 EN 10025-2 N EN 10025-3 NL EN 10025-3 450 J0 EN 10025-2 P 265 GH EN 10028-2 NB EN 10120 355 NH EN 10028-3 M EN 10028-5 ML1 EN 10028-5 Q EN 10028-6

### Category 2: Steel specified by chemical composition

In addition to the descriptive steel grade naming system indicated above, within EN 10027-2 is defined a system for creating unique steel grade numbers. While less descriptive and intuitive than the grand names they are easier to tabulate and use in data processing applications.

The number is in the following format: x.yyzz(zz) Where x is the material type (only 1 is specified so far), yy is the steel group number (specified in EN10027-2) and zz(zz) is a sequential number designated by the certifying body, the number in brackets being unused but reserved for later use.

The steel groups are indicated below:

Code Type Non-alloy steels 00 & 90 Basic steels 0x & 9x Quality steels 1x Special steels Alloy steels 2x Tool steels 3x Miscellaneous steels 4x Stainless and heat resistant steels 5x – 8x Structural, pressure vessel and engineering steels 08 & 98 Special physical properties 09 & 99 Other purpose steels

The current certification body is the [VDEh](/source/Stahlinstitut_VDEh) in [Düsseldorf, Germany](/source/D%C3%BCsseldorf%2C_Germany).

## Comparisons

Below is a table comparing steel grades from different grading systems.

Comparison of steel grades by chemistry[4][5][6] EN steel number (Europe) EN steel name (Europe) ASTM grade (USA) AISI/SAE grade (USA) UNS (USA) DIN (Germany) BS (UK) UNI (Italy) JIS (Japan) Carbon steels 1.1141 1.0401 1.0453 C15D C18D 1010 1018 CK15 C15 C16.8 040A15 080M15 080A15 EN3B C15 C16 1C15 S12C S15 S15CK S15C 1.0503 1.1191 1.1193 1.1194 C45 1045[7] C45 CK45 CF45 CQ45 060A47 080A46 080M46 C45 1C45 C46 C43 S45C S48C 1.0726 1.0727 35S20 45S20 1140/1146 35S20 45S20 212M40 En8M 1.0715 1.0736 11SMn37 1215 9SMn28 9SMn36 230M07 En1A CF9SMn28 CF9SMn36 SUM 25 SUM 22 1.0718 1.0737 11SMnPb30 11SMnPb37 12L14 9SMnPb28 9SMnPb36 230M07 Leaded En1B Leaded CF9SMnPb29 CF9SMnPb36 SUM 22 SUM 23 SUM 24 1.1555 C120U C125W BW1C C120KU SK2 Alloy steels 1.7218 4130 25CrMo4 GS-25CrMo4 708A30 CDS110 25CrMo4 (KB) 30CrMo4 SCM 420 SCM 430 SCCrM1 1.7223 1.7225 1.7227 1.3563 42CrMo4 4140/4142 41CrMo4 42CrMo4 42CrMoS4 43CrMo4 708M40 708A42 709M40 En19 En19C 41CrMo4 38CrMo4 (KB) G40 CrMo4 42CrMo4 SCM 440 SCM 440H SNB 7 SCM 4M SCM 4 1.6582 1.6562 34CrNiMo6 4340 34CrNiMo6 40NiCrMo8-4 817M40 En24 35NiCrMo6 (KB) 40NiCrMo7 (KB) SNCM 447 SNB24-1-5 1.6543 1.6523 20NiCrMo2-2 8620 21NiCrMo22 21NiCrMo2 805A20 805M20 20NiCrMo2 SNCM 200 (H) 1.5415 16Mo3 A204 A/B/C K12822 K12320 K12020 K11820 15Mo3 1503-243B 240 243 15Mo3 16Mo3 STBA12 Stainless steels 1.4310 X10CrNi18-8 301[8] S30100 1.4318 X2CrNiN18-7 301LN 1.4305 X8CrNiS18-9 303 S30300 X10CrNiS18-9 303S 31 En58M X10CrNiS18-09 SUS 303 1.4301 X2CrNi19-11 X2CrNi18-10 304[8] S30400 X5CrNi18-9 X5CrNi18-10 XCrNi19-9 304S 15 304S 16 304S 18 304S 25 En58E X5CrNi18-10 SUS 304 SUS 304-CSP 1.4306 X2CrNi19-11 304L S30403 304S 11 SUS304L 1.4311 X2CrNiN18-10 304LN S30453 1.4948 X6CrNi18-11 304H S30409 1.4303 X5CrNi18-12 305 S30500 1.4401 1.4436 X5CrNiMo17-12-2 X5CrNiMo18-14-3 316[8] S31600 X5CrNiMo17 12 2 X5CrNiMo17 13 3 X5CrNiMo 19 11 X5CrNiMo 18 11 316S 29 316S 31 316S 33 En58J X5CrNiMo17 12 X5CrNiMo17 13 X8CrNiMo17 13 SUS 316 SUS316TP 1.4404 X2CrNiMo17-12-2 316L S31603 316S 11 SUS316L 1.4406 1.4429 X2CrNiMoN17-12-2 X2CrNiMoN17-13-3 316LN S31653 1.4462 X2CrNiMoN22.5.3 S31803 S32205 X2CrNiMoN22.5.3 1.4571 316Ti S31635 X6CrNiMoTi17-12 320S 33 1.4438 X2CrNiMo18-15-4 317L S31703 1.4541 321 S32100 X6CrNiTi18-10 321S 31 SUS321 1.4848 GX40CrNiSi25-20 A351 HK40 J94204 SEW 595 GX40CrNiSi25-20 310C40 SCH22 1.4859 GX10NiCrSiNb32-20 N08151 GX10NiCrSiNb32-20 1.4878 X12CrNiTi18-9 X8CrNiTi18-10 321H S32109 1.4906 X7CrNiNb18-10 347H S34709 1.4512 X6CrTi12 409 S40900 SUH409 410 S41000 1.4016 430 S43000 X6Cr17 430S 17 SUS430 440A S44002 1.4112 440B S44003 1.4125 440C S44004 X105CrMo17 SUS440C 1.4104 430F S44020 X14CrMoS17 SUS430F 1.4057 X17CrNi16-2 431 X[9] S43100 X16CrNi16 431S 29 SUS431 1.5423 16Mo5 A335 P1 4520 4419H 4419 K11522 16Mo5 STPA12 1.7715 14MoV6-3 A335 P2 K11547 14MoV6-3 660 STPA20 1.7335 1.7338 13CrMo4-5 10CrMo5-5 A335 P11 K11597 STPA23 1.7375 1.7380 1.7383 10CrMo9-10 11CrMo9-10 12CrMo9-10 A335 P22 K21590 17175 10CrMo910 STPA24 1.7362 1.7366 X11CrMo5 X12CrMo5 12CrMo19-5 A335 P5 501 502 K41545 S50100 S50200 STPA25 1.7386 X11CrMo9-1 X12CrMo9-1 A335 P9 503 S50400 S50488 K90941 STPA26 1.4903 X10CrMoVNbN9-1 A335 P91 K91560 X10CrMoVNbN9-1 1.4905 1.4906 X11CrMoWVNb9-1-1 X12CrMoWVNbN10-1-1 A335 P92 K92460 X11CrMoWVNb9-1-1 X12CrMoWVNbN10-1-1 1.4539 X1NiCrMoCu25-20-5 904L N08904 1.4547 X1CrNiMoCuN20-18-7 S31254 1.4565 NIT50 S20910 NIT60 S21800 Tool steels 1.2363 X100CrMoV5 A-2 T30102[10] X100CrMoV51 BA 2 X100CrMoV5-1 KU SKD 12 A-3 T30103[11] A-4 T30104[12] A-6 T30106[13] A-7 T30107[14] A-8 T30108[15] A-9 T30109[16] 1.2365 X32CrMoV3-3 32CrMoV12-28 H10 T20810 X32CrMoV3-3 32CrMoV12-28 SKD 7 1.2379 X153CrMoV12 D-2 X153CrMoV12-1 BD 2 X155CrVMo12-1 SKD 11 1.2510 O-1 100MnCrW4 Bo 1 95MnWCr-5 KU

## American Petroleum Institute (API) steel grades

The American Petroleum Institute has a standardized steel grading system for various properties of steel composites.[17]

### Color coding

In order to clearly distinguish the steel grade, tubing, casing and its coupling should be painted with color codes respectively. Color bands should be painted on [tubing and casing](http://www.octgproducts.com/OCTG-tubing.html) body longer than 600mm to either end. The whole outer-body of the coupling needs to be painted color and then color codes.

Steel Grade Coupling Tubular Body API Tubing and Casing H40 None None or black band at the manufacturer's option J55 all green. one green band K55 all green two green bands N80-1 all red one red band N80-Q all red + one green band one red band + one green band L80-1 all red + one brown band one red band + one brown band L80-9Cr colorless + two yellow bands one red band + one brown band + two yellow bands L80-13Cr colorless + one yellow band one red band + one brown band + one yellow band C90-1 all purple one purple band T95-1 all silver one silver band C110 all white + two brown bands one white band + two brown bands P110 all white one white band Q125 all orange one orange band

API 5B and 5CT provide various steel grades and color codes of each grade, with general information of casing and tubing.

## References

### Notes

1. **[^](#cite_ref-1)** *EN 10027*, European Committee for Standardization

1. **[^](#cite_ref-2)** ["EN 10027 Steel Names and their Meaning"](http://www.oakleysteel.co.uk/thick-steel-plates/steel-information/guide-en-10027-steel-names).

1. **[^](#cite_ref-3)** ["Designation systems for steels"](https://web.archive.org/web/20220325222517/https://www.3ppars.com/WebsiteImages/download/48771479212.PDF) (PDF). Archived from [the original](https://www.3ppars.com/WebsiteImages/download/48771479212.PDF) (PDF) on 2022-03-25.

1. **[^](#cite_ref-4)** Bringas, John E, ed. (2016). [*Handbook of Comparative World Steel Standards, 5th Edition*](https://www.astm.org/ds67d-eb.html). [doi](/source/Doi_(identifier)):[10.1520/ds67d-eb](https://doi.org/10.1520%2Fds67d-eb). [ISBN](/source/ISBN_(identifier)) [978-0-8031-7077-3](https://en.wikipedia.org/wiki/Special:BookSources/978-0-8031-7077-3). Retrieved 2022-04-28.

1. **[^](#cite_ref-5)** ["Standards comparison"](https://web.archive.org/web/20081224082423/http://www.metricmetal.com/standards_comparison.htm). Archived from [the original](http://metricmetal.com/standards_comparison.htm) on 2008-12-24. Retrieved 2008-12-31..

1. **[^](#cite_ref-6)** Oberg, pp. 411-412.

1. **[^](#cite_ref-7)** ["1045 Steel"](https://web.archive.org/web/20220724124114/https://steel-bar.com/1045-steel/). *steel-bar.com*. 16 May 2022. Archived from [the original](https://steel-bar.com/1045-steel/) on July 24, 2022.

1. ^ [***a***](#cite_ref-3xx_8-0) [***b***](#cite_ref-3xx_8-1) [***c***](#cite_ref-3xx_8-2) ["Stainless Steel Powder: 301 vs. 304 vs. 316"](https://powder.samaterials.com/stainless-steel-powder-301-vs-304-vs-316.html). *Stanford Advanced Materials*. Retrieved Sep 7, 2024.

1. **[^](#cite_ref-9)** ["Chronifer M-15 X (431 X) steel developed by L. Klein SA"](https://web.archive.org/web/20170113113338/http://www.kleinmetals.ch/steel/chronifer-m-15-x-watchmaking-alloys.htm). *www.kleinmetals.ch*. Archived from [the original](http://www.kleinmetals.ch/steel/chronifer-m-15-x-watchmaking-alloys.htm) on 2017-01-13. Retrieved 2017-01-12.

1. **[^](#cite_ref-10)** [*AISI A2*](http://www.efunda.com/materials/alloys/tool_steels/show_tool.cfm?ID=AISI_A2&show_prop=all&Page_Title=AISI%20A2), Efunda, [archived](https://web.archive.org/web/20100515140752/http://www.etunda.com/) from the original on 2010-05-15, retrieved 2010-12-25.

1. **[^](#cite_ref-11)** [*AISI A3*](http://www.efunda.com/materials/alloys/tool_steels/show_tool.cfm?ID=AISI_A3&show_prop=all&Page_Title=AISI%20A3), Efunda, [archived](https://www.webcitation.org/5vFGw8Bhe?url=http://lastminutetraveldealss.us/?rid=16110678&rname=etunda.com&OptId=11) from the original on 2010-12-25, retrieved 2010-12-25.

1. **[^](#cite_ref-12)** [*AISI A4*](http://www.efunda.com/materials/alloys/tool_steels/show_tool.cfm?ID=AISI_A4&show_prop=all&Page_Title=AISI%20A4), Efunda, [archived](https://web.archive.org/web/20100515140752/http://www.etunda.com/) from the original on 2010-05-15, retrieved 2010-12-25.

1. **[^](#cite_ref-13)** [*AISI A6*](http://www.efunda.com/materials/alloys/tool_steels/show_tool.cfm?ID=AISI_A6&show_prop=all&Page_Title=AISI%20A6), Efunda, [archived](https://www.webcitation.org/5vFGw8Bhe?url=http://lastminutetraveldealss.us/?rid=16110678&rname=etunda.com&OptId=11) from the original on 2010-12-25, retrieved 2010-12-25.

1. **[^](#cite_ref-14)** [*AISI A7*](http://www.efunda.com/materials/alloys/tool_steels/show_tool.cfm?ID=AISI_A7&show_prop=all&Page_Title=AISI%20A7), Efunda, [archived](https://www.webcitation.org/5vFGw8Bhe?url=http://lastminutetraveldealss.us/?rid=16110678&rname=etunda.com&OptId=11) from the original on 2010-12-25, retrieved 2010-12-25.

1. **[^](#cite_ref-15)** [*AISI A8*](http://www.efunda.com/materials/alloys/tool_steels/show_tool.cfm?ID=AISI_A8&show_prop=all&Page_Title=AISI%20A8), Efunda, [archived](https://web.archive.org/web/20100515140752/http://www.etunda.com/) from the original on 2010-05-15, retrieved 2010-12-25.

1. **[^](#cite_ref-16)** [*AISI A9*](http://www.efunda.com/materials/alloys/tool_steels/show_tool.cfm?ID=AISI_A9&show_prop=all&Page_Title=AISI%20A9), Efunda, [archived](https://web.archive.org/web/20100515140752/http://www.etunda.com/) from the original on 2010-05-15, retrieved 2010-12-25.

1. **[^](#cite_ref-17)** ["API Steel Grade for Casing & Tubing"](https://www.drinol.com/technology/api-steel-grade.html). *www.drinol.com*. Retrieved 2025-06-13.

### Bibliography

- Oberg, E.; et al. (1996), *Machinery's Handbook* (25th ed.), Industrial Press Inc, [ISBN](/source/ISBN_(identifier)) [3540311874](https://en.wikipedia.org/wiki/Special:BookSources/3540311874)

## External links

- [Steel classification according to EN 10027-2.Free searchable database "European steel and alloy grades"](https://www.steelnumber.com/en/number_en10027_eu.php)

- [Comparison of various steel standards](http://www.hagener-feinstahl.de/werkstoffliste2007.php?lng=en) [Archived](https://web.archive.org/web/20190427173039/http://www.hagener-feinstahl.de/werkstoffliste2007.php?lng=en) 2019-04-27 at the [Wayback Machine](/source/Wayback_Machine)

- [Comparison of various tool steel standards](https://www.westyorkssteel.com/steel-specifications/international-standards/tool-steel/)

- [General guide to the EN 10027 steel name and numbering systems.](https://www.roymech.co.uk/Useful_Tables/Matter/Steel_Europe.html)

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