Steel grades to classify various steels by their composition and physical properties have been developed by a number of standards organizations.

Steel grades standards by country

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 and UK standards are being withdrawn and replaced by European Standards (EN).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 (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.
  2. 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 symbolMeaningMechanical PropertyDetails
SStructural steel Minimum Yield Strength
PSteel for pressure lines and vesselsMinimum Yield Strength
LSteel for pipe and tubeMinimum Yield Strength
EEngineering steelsMinimum Yield Strength
BSteel for reinforced concreteCharacteristic Yield Case
RSteel for rail useMinimum Yield Case
HHigh Tensile Strength Flat productsMinimum Yield CaseIf followed by T then the given mechanical property is minimum tensile strength
DFlat Products for Cold FormingFollowed by C, D or X and two numbers characterising steel
TTinmill ProductsNominal Yield Case
MElectrical SteelNumber = 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
J27 JRRoom temperature
K40 J00 °C
L60 J2-20 °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:

CodeCondition
AAnnealed
QTQuenched and tempered
NNormalised
SRStress relieved
CCold worked
UUntreated
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:

CodeType
Non-alloy steels
00 & 90Basic steels
0x & 9xQuality steels
1xSpecial steels
Alloy steels
2xTool steels
3xMiscellaneous steels
4xStainless and heat resistant steels
5x – 8xStructural, pressure vessel and engineering steels
08 & 98Special physical properties
09 & 99Other purpose steels

The current certification body is the VDEh in Düsseldorf, 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		C451045[7]C45
CK45
CF45
CQ45		060A47
080A46
080M46		C45
1C45
C46
C43		S45C
S48C
1.0726
1.0727		35S20
45S20		1140/114635S20
45S20		212M40
En8M
1.0715
1.0736		11SMn3712159SMn28
9SMn36		230M07
En1A		CF9SMn28
CF9SMn36		SUM 25
SUM 22
1.0718
1.0737		11SMnPb30
11SMnPb37		12L149SMnPb28
9SMnPb36		230M07 Leaded
En1B Leaded		CF9SMnPb29
CF9SMnPb36		SUM 22
SUM 23
SUM 24
1.1555C120UC125WBW1CC120KUSK2
Alloy steels
1.7218413025CrMo4
GS-25CrMo4		708A30
CDS110		25CrMo4 (KB)
30CrMo4		SCM 420
SCM 430
SCCrM1
1.7223
1.7225
1.7227
1.3563		42CrMo44140/414241CrMo4
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		34CrNiMo6434034CrNiMo6
40NiCrMo8-4		817M40
En24		35NiCrMo6 (KB)
40NiCrMo7 (KB)		SNCM 447
SNB24-1-5
1.6543
1.6523		20NiCrMo2-2862021NiCrMo22
21NiCrMo2		805A20
805M20		20NiCrMo2SNCM 200 (H)
1.541516Mo3A240 A/B/CK12822
K12320
K12020
K11820		15Mo31503-243B
240
243		15Mo3
16Mo3		STBA12
Stainless steels
1.4310X10CrNi18-8301S30100
1.4318X2CrNiN18-7301LN
1.4305X8CrNiS18-9303S30300X10CrNiS18-9303S 31
En58M		X10CrNiS18-09SUS 303
1.4301X2CrNi19-11
X2CrNi18-10		304S30400X5CrNi18-9
X5CrNi18-10
XCrNi19-9		304S 15
304S 16
304S 18
304S 25
En58E		X5CrNi18-10SUS 304
SUS 304-CSP
1.4306X2CrNi19-11304LS30403304S 11SUS304L
1.4311X2CrNiN18-10304LNS30453
1.4948X6CrNi18-11304HS30409
1.4303X5CrNi18-12305S30500
1.4401
1.4436		X5CrNiMo17-12-2
X5CrNiMo18-14-3		316S31600X5CrNiMo17 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
1.4404X2CrNiMo17-12-2316LS31603316S 11SUS316L
1.4406
1.4429		X2CrNiMoN17-12-2
X2CrNiMoN17-13-3		316LNS31653
1.4571316TiS31635X6CrNiMoTi17-12320S 33
1.4438X2CrNiMo18-15-4317LS31703
1.4541321S32100X6CrNiTi18-10321S 31SUS321
1.4848GX40CrNiSi25-20A351 HK40J94204SEW 595 GX40CrNiSi25-20310C40SCH22
1.4859GX10NiCrSiNb32-20N08151GX10NiCrSiNb32-20
1.4878X12CrNiTi18-9
X8CrNiTi18-10		321HS32109
1.4906X7CrNiNb18-10347HS34709
1.4512X6CrTi12409S40900SUH409
410S41000
1.4016430S43000X6Cr17430S 17SUS430
440AS44002
1.4112440BS44003
1.4125440CS44004X105CrMo17SUS440C
1.4104430FS44020X14CrMoS17SUS430F
1.4057 X17CrNi16-2 431 X[8] S43100 X16CrNi16 431S 29 SUS431
1.542316Mo5A335 P14520
4419H
4419		K1152216Mo5STPA12
1.771514MoV6-3A335 P2K1154714MoV6-3660STPA20
1.7335
1.7338		13CrMo4-5
10CrMo5-5		A335 P11K11597STPA23
1.7375
1.7380
1.7383		10CrMo9-10
11CrMo9-10
12CrMo9-10		A335 P22K2159017175 10CrMo910STPA24
1.7362
1.7366		X11CrMo5
X12CrMo5
12CrMo19-5		A335 P5501
502		K41545
S50100
S50200		STPA25
1.7386X11CrMo9-1
X12CrMo9-1		A335 P9503S50400
S50488
K90941		STPA26
1.4903X10CrMoVNbN9-1A335 P91K91560X10CrMoVNbN9-1
1.4905
1.4906		X11CrMoWVNb9-1-1
X12CrMoWVNbN10-1-1		A335 P92K92460X11CrMoWVNb9-1-1
X12CrMoWVNbN10-1-1
1.4539X1NiCrMoCu25-20-5904LN08904
1.4547X1CrNiMoCuN20-18-7S31254
1.4565 NIT50 S20910
NIT60 S21800
Tool steels
1.2363X100CrMoV5A-2T30102[9]X100CrMoV51BA 2X100CrMoV5-1 KUSKD 12
A-3T30103[10]
A-4T30104[11]
A-6T30106[12]
A-7T30107[13]
A-8T30108[14]
A-9T30109[15]
1.2365X32CrMoV3-3
32CrMoV12-28		H10T20810X32CrMoV3-3
32CrMoV12-28		SKD 7
1.2379X153CrMoV12D-2X153CrMoV12-1BD 2X155CrVMo12-1SKD 11
1.2510O-1100MnCrW4Bo 195MnWCr-5 KU

American Petroleum Institute (API) steel grades

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 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, offering detailed and overall information of casing and tubing, which help you clearly pick out the most suitable products for different well application.

References

Notes

  1. ↑ EN 10027, European Committee for Standardization
  2. ↑ "EN 10027 Steel Names and their Meaning".
  3. ↑ https://www.3ppars.com/WebsiteImages/download/48771479212.PDF
  4. ↑ Bringas, John E, ed. (2016). Handbook of Comparative World Steel Standards, 5th Edition. doi:10.1520/ds67d-eb. ISBN 978-0-8031-7077-3. Retrieved 2022-04-28. {{cite book}}: |website= ignored (help)
  5. ↑ "Standards comparison". Retrieved 2008-12-31..
  6. ↑ Oberg, pp. 411-412.
  7. ↑ "1045 Steel". steel-bar.com. 16 May 2022.
  8. ↑ "Chronifer M-15 X (431 X) steel developed by L. Klein SA". www.kleinmetals.ch. Retrieved 2017-01-12.
  9. ↑ AISI A2, Efunda, archived from the original on 2010-05-15, retrieved 2010-12-25.
  10. ↑ AISI A3, Efunda, archived from the original on 2010-12-25, retrieved 2010-12-25.
  11. ↑ AISI A4, Efunda, archived from the original on 2010-05-15, retrieved 2010-12-25.
  12. ↑ AISI A6, Efunda, archived from the original on 2010-12-25, retrieved 2010-12-25.
  13. ↑ AISI A7, Efunda, archived from the original on 2010-12-25, retrieved 2010-12-25.
  14. ↑ AISI A8, Efunda, archived from the original on 2010-05-15, retrieved 2010-12-25.
  15. ↑ AISI A9, Efunda, archived from the original on 2010-05-15, retrieved 2010-12-25.

Bibliography

  • Oberg, E.; et al. (1996), Machinery's Handbook (25th ed.), Industrial Press Inc, ISBN 3540311874
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