Steel names based on letter symbols

ISO/TS 4949:2016 specifies rules for the designation of internationally standardized steel grades by means of symbolic letters and numbers to express application and principal characteristics (e.g. mechanical, physical, chemical) so as to provide an abbreviated identification of steel grades. NOTE 1 In order to avoid ambiguity, the principal symbols established according to this document can be supplemented by additional symbols identifying additional characteristics of the steel or steel product, e.g. suitability for use at high or low temperatures, surface condition, treatment condition, deoxidation. NOTE 2 These rules can also be applied to nationally or regionally standardized steels.

Désignations des aciers fondées sur des lettres symboles

General Information

Status
Published
Publication Date
26-Oct-2016
Technical Committee
Drafting Committee
Current Stage
6060 - International Standard published
Start Date
05-Sep-2016
Completion Date
27-Oct-2016
Ref Project

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TECHNICAL ISO/TS
SPECIFICATION 4949
Second edition
2016-11-01
Steel names based on letter symbols
Désignations des aciers fondées sur des lettres symboles
Reference number
ISO/TS 4949:2016(E)
ISO 2016
---------------------- Page: 1 ----------------------
ISO/TS 4949:2016(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TS 4949:2016(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principles ..................................................................................................................................................................................................................... 1

4.1 A unique steel name ........................................................................................................................................................................... 1

4.2 Formulation of steel names .......................................................................................................................................................... 1

4.3 Allocation of steel names ............................................................................................................................................................... 1

5 Reference to product standards ........................................................................................................................................................... 1

6 Classification of steel names .................................................................................................................................................................... 2

7 Structure of steel names ............................................................................................................................................................................... 2

7.1 Initial symbol for steel castings ................................................................................................................................................ 2

7.2 Steels designated according to their application and mechanical or physical

properties (group 1) .......................................................................................................................................................................... 2

7.3 Steels designated according to chemical composition (group 2)................................................................ 4

7.3.1 Non-alloy steels (except free-cutting steels) with an average manganese

content < 1 % (sub-group 2.1) ............................................................................................................................. 4

7.3.2 Non-alloy steels with an average manganese content ≥ 1 %, non-alloy
free-cutting steels and alloy steels (except high speed steels) where the

average content, by mass, of every alloying element is < 5 % (sub-group 2.2) ......... 4

7.3.3 Alloy steels (except high speed steels) where the average content by mass

of at least one alloying element is ≥ 5 % (sub-group 2.3) ............................................................ 5

7.3.4 High speed steel (sub-group 2.4) ...................................................................................................................... 5

8 Additional symbols ............................................................................................................................................................................................ 5

Annex A (normative) Additional symbols indicating special requirements ...............................................................6

Annex B (normative) Additional symbols indicating type of coating ................................................................................. 7

Annex C (normative) Additional symbols indicating treatment condition ..................................................................8

Bibliography ................................................................................................................................................................................................................................ 9

© ISO 2016 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/TS 4949:2016(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,

as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the

Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.

The committee responsible for this document is ISO/TC 17, Steel.

This second edition cancels and replaces the first edition (ISO/TS 4949:2003), which has been

technically revised.
iv © ISO 2016 – All rights reserved
---------------------- Page: 4 ----------------------
TECHNICAL SPECIFICATION ISO/TS 4949:2016(E)
Steel names based on letter symbols
1 Scope

This document specifies rules for the designation of internationally standardized steel grades by means

of symbolic letters and numbers to express application and principal characteristics (e.g. mechanical,

physical, chemical) so as to provide an abbreviated identification of steel grades.

NOTE 1 In order to avoid ambiguity, the principal symbols established according to this document can be

supplemented by additional symbols identifying additional characteristics of the steel or steel product, e.g.

suitability for use at high or low temperatures, surface condition, treatment condition, deoxidation.

NOTE 2 These rules can also be applied to nationally or regionally standardized steels.

2 Normative references
There are no normative references in this document.
3 Terms and definitions

For the purposes of this document, the terms and definitions in ISO 4948-1, ISO 4948-2 and

ISO 6929 apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
4 Principles
4.1 A unique steel name
There shall be one unique steel name for each steel.
4.2 Formulation of steel names

Unless otherwise specified in this document, the symbols used in the steel name shall be written

without spaces.
4.3 Allocation of steel names

For steels specified in International Standards, Technical Specifications or Technical Reports, steel

names shall be allocated by the relevant subcommittee of ISO/TC 17.
5 Reference to product standards

The complete designation of a steel product where quoted in orders or similar contractual documents

shall include, in addition to the steel name, an indication of the technical delivery requirement in which

the steel is specified. For steels specified in standards this shall be the reference number of the relevant

product standard.
© ISO 2016 – All rights reserved 1
---------------------- Page: 5 ----------------------
ISO/TS 4949:2016(E)

Details of the structure of the steel name for the steel or steel product shall be provided in the relevant

product or dimensional standard.
6 Classification of steel names
For the purpose of designation, steel names are classified into two main groups.

— Group 1: Steels designated according to their application and mechanical or physical properties.

See 7.2.

— Group 2: Steels designated according to their chemical composition and further divided into four

sub-groups. See 7.3.
7 Structure of steel names
7.1 Initial symbol for steel castings

Where a steel is specified in the form of a steel casting, its steel name as specified in 7.2 and 7.3 shall be

preceded by the letter G.
7.2 Steels designated according to their application and mechanical or physical
properties (group 1)
The coding shall comprise the following principal symbols.
a) S = structural steels.
P = steels for pressure purposes.
L = steels for linepipe.
E = engineering steels.

Each followed by a number being the specified minimum yield strength in MPa for the smallest

thickness range.

NOTE 1 The term “yield strength” as used in this document refers to upper or lower yield strength, R or

R , proof strength, R , or proof strength total extension, R , depending on the requirement specified in the

eL p t
relevant product standard.
NOTE 2 1 MPa = 1 N/mm .

When the specified minimum tensile strength is used instead of the specified minimum yield

strength, the letter T shall be added after the principal symbol, e.g. PT.

In order to distinguish structural steels of different regions an additional letter “G” may be added,

e.g. steel grade SG345, see ISO 630-2.
b) B = steels for reinforcing concrete.
Followed by a number being the characteristic yield stre
...

TECHNICAL ISO/TS
SPECIFICATION 4949
Second edition
Steel names based on letter symbols
Désignations des aciers fondées sur des lettres symboles
PROOF/ÉPREUVE
Reference number
ISO/TS 4949:2016(E)
ISO 2016
---------------------- Page: 1 ----------------------
ISO/TS 4949:2016(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TS 4949:2016(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principles ..................................................................................................................................................................................................................... 1

4.1 A unique steel name ........................................................................................................................................................................... 1

4.2 Formulation of steel names .......................................................................................................................................................... 1

4.3 Allocation of steel names ............................................................................................................................................................... 1

5 Reference to product standards ........................................................................................................................................................... 2

6 Classification of steel names .................................................................................................................................................................... 2

7 Structure of steel names ............................................................................................................................................................................... 2

7.1 Initial symbol for steel castings ................................................................................................................................................ 2

7.2 Steels designated according to their application and mechanical or physical

properties (group 1) .......................................................................................................................................................................... 2

7.3 Steels designated according to chemical composition (group 2)................................................................ 4

7.3.1 Non-alloy steels (except free-cutting steels) with an average manganese

content < 1 % (sub-group 2.1) ............................................................................................................................. 4

7.3.2 Non-alloy steels with an average manganese content ≥ 1 %, non-alloy
free-cutting steels and alloy steels (except high speed steels) where the

average content, by mass, of every alloying element is < 5 % (sub-group 2.2) ......... 4

7.3.3 Alloy steels (except high speed steels) where the average content by mass

of at least one alloying element is ≥ 5 % (sub-group 2.3) ............................................................ 5

7.3.4 High speed steel (sub-group 2.4) ...................................................................................................................... 5

8 Additional symbols ............................................................................................................................................................................................ 6

Annex A (normative) Additional symbols indicating special requirements ...............................................................7

Annex B (normative) Additional symbols indicating type of coating ................................................................................. 8

Annex C (normative) Additional symbols indicating treatment condition ..................................................................9

Bibliography .............................................................................................................................................................................................................................10

© ISO 2016 – All rights reserved PROOF/ÉPREUVE iii
---------------------- Page: 3 ----------------------
ISO/TS 4949:2016(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical

Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information

The committee responsible for this document is ISO/TC 17, Steel.

This second edition cancels and replaces the first edition (ISO 4949:2003), which has been technically

revised.
iv PROOF/ÉPREUVE © ISO 2016 – All rights reserved
---------------------- Page: 4 ----------------------
TECHNICAL SPECIFICATION ISO/TS 4949:2016(E)
Steel names based on letter symbols
1 Scope

This Technical Specification specifies rules for the designation of internationally standardized steel

grades by means of symbolic letters and numbers to express application and principal characteristics

(e.g. mechanical, physical, chemical) so as to provide an abbreviated identification of steel grades.

These rules are applicable to nationally or regionally standardized steels.

NOTE In order to avoid ambiguity, the principal symbols established according to this Technical Specification

can be supplemented by additional symbols identifying additional characteristics of the steel or steel product,

e.g. suitability for use at high or low temperatures, surface condition, treatment condition, deoxidation.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

ISO 4948-1, Steels — Classification — Part 1: Classification of steels into unalloyed and alloy steels based

on chemical composition

ISO 4948-2, Steels — Classification — Part 2: Classification of unalloyed and alloy steels according to main

quality classes and main property or application characteristics
ISO 6929, Steel products — Vocabulary
3 Terms and definitions

For the purposes of this document, the terms and definitions in ISO 4948-1, ISO 4948-2 and

ISO 6929 apply.
4 Principles
4.1 A unique steel name
There shall be one unique steel name for each steel.
4.2 Formulation of steel names

Unless otherwise specified in this Technical Specification, the symbols used in the steel name shall be

written without spaces.
4.3 Allocation of steel names

For steels specified in International Standards, Technical Specifications or Technical Reports, steel

names shall be allocated by the relevant subcommittee of ISO/TC 17.
© ISO 2016 – All rights reserved PROOF/ÉPREUVE 1
---------------------- Page: 5 ----------------------
ISO/TS 4949:2016(E)
5 Reference to product standards

The complete designation of a steel product where quoted in orders or similar contractual documents

shall include, in addition to the steel name, an indication of the technical delivery requirement in which

the steel is specified. For steels specified in standards this shall be the reference number of the relevant

product standard.

Details of the structure of the steel name for the steel or steel product shall be provided in the relevant

product or dimensional standard.
6 Classification of steel names
For the purpose of designation, steel names are classified into two main groups.

— Group 1 steels designated according to their application and mechanical or physical properties,

see 7.2.

— Group 2 steels designated according to their chemical composition and further divided into four

sub-groups, see 7.3.
7 Structure of steel names
7.1 Initial symbol for steel castings

Where a steel is specified in the form of a steel casting, its steel name as specified in 7.2 and 7.3 shall be

preceded by the letter G.
7.2 Steels designated according to their application and mechanical or physical
properties (group 1)
The coding shall comprise the following principal symbols.
a) S = structural steels.
P = steels for pressure purposes.
L = steels for linepipe.
E = engineering steels.

Each followed by a number being the specified minimum yield strength in MPa for the smallest

thickness range.

NOTE 1 The term “yield strength” as used in this Technical Specification refers to upper or lower yield

strength, R or R , proof strength, R , or proof strength total extension, R , depending on the requirement

eH eL p t
specified in the relevant product standard.
NOTE 2 1 MPa = 1 N/mm .

When the specified minimum tensile strength is used instead of the specified minimum yield

strength, the letter T shall be added after the p
...

TECHNICAL ISO/TS
SPECIFICATION 4949
Second edition
2016-##-##
Steel names based on letter symbols
Désignations des aciers fondées sur des lettres symboles
PROOF/ÉPREUVE
Reference number
ISO/TS 4949:2016(E)
ISO 2016
---------------------- Page: 1 ----------------------
ISO/TS 4949:2016(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TS 4949:2016(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principles ..................................................................................................................................................................................................................... 1

4.1 A unique steel name ........................................................................................................................................................................... 1

4.2 Formulation of steel names .......................................................................................................................................................... 1

4.3 Allocation of steel names ............................................................................................................................................................... 1

5 Reference to product standards ........................................................................................................................................................... 1

6 Classification of steel names .................................................................................................................................................................... 2

7 Structure of steel names ............................................................................................................................................................................... 2

7.1 Initial symbol for steel castings ................................................................................................................................................ 2

7.2 Steels designated according to their application and mechanical or physical

properties (group 1) .......................................................................................................................................................................... 2

7.3 Steels designated according to chemical composition (group 2)................................................................ 4

7.3.1 Non-alloy steels (except free-cutting steels) with an average manganese

content < 1 % (sub-group 2.1) ............................................................................................................................. 4

7.3.2 Non-alloy steels with an average manganese content ≥ 1 %, non-alloy
free-cutting steels and alloy steels (except high speed steels) where the

average content, by mass, of every alloying element is < 5 % (sub-group 2.2) ......... 4

7.3.3 Alloy steels (except high speed steels) where the average content by mass

of at least one alloying element is ≥ 5 % (sub-group 2.3) ............................................................ 5

7.3.4 High speed steel (sub-group 2.4) ...................................................................................................................... 5

8 Additional symbols ............................................................................................................................................................................................ 5

Annex A (normative) Additional symbols indicating special requirements ...............................................................6

Annex B (normative) Additional symbols indicating type of coating ................................................................................. 7

Annex C (normative) Additional symbols indicating treatment condition ..................................................................8

Bibliography ................................................................................................................................................................................................................................ 9

© ISO 2016 – All rights reserved PROOF/ÉPREUVE iii
---------------------- Page: 3 ----------------------
ISO/TS 4949:2016(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,

as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the

Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.

The committee responsible for this document is ISO/TC 17, Steel.

This second edition cancels and replaces the first edition (ISO/TS 4949:2003), which has been

technically revised.
iv PROOF/ÉPREUVE © ISO 2016 – All rights reserved
---------------------- Page: 4 ----------------------
TECHNICAL SPECIFICATION ISO/TS 4949:2016(E)
Steel names based on letter symbols
1 Scope

This document specifies rules for the designation of internationally standardized steel grades by means

of symbolic letters and numbers to express application and principal characteristics (e.g. mechanical,

physical, chemical) so as to provide an abbreviated identification of steel grades.

NOTE 1 In order to avoid ambiguity, the principal symbols established according to this document can be

supplemented by additional symbols identifying additional characteristics of the steel or steel product, e.g.

suitability for use at high or low temperatures, surface condition, treatment condition, deoxidation.

NOTE 2 These rules can also be applied to nationally or regionally standardized steels.

2 Normative references
There are no normative references in this document.
3 Terms and definitions

For the purposes of this document, the terms and definitions in ISO 4948-1, ISO 4948-2 and

ISO 6929 apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
4 Principles
4.1 A unique steel name
There shall be one unique steel name for each steel.
4.2 Formulation of steel names

Unless otherwise specified in this document, the symbols used in the steel name shall be written

without spaces.
4.3 Allocation of steel names

For steels specified in International Standards, Technical Specifications or Technical Reports, steel

names shall be allocated by the relevant subcommittee of ISO/TC 17.
5 Reference to product standards

The complete designation of a steel product where quoted in orders or similar contractual documents

shall include, in addition to the steel name, an indication of the technical delivery requirement in which

the steel is specified. For steels specified in standards this shall be the reference number of the relevant

product standard.
© ISO 2016 – All rights reserved PROOF/ÉPREUVE 1
---------------------- Page: 5 ----------------------
ISO/TS 4949:2016(E)

Details of the structure of the steel name for the steel or steel product shall be provided in the relevant

product or dimensional standard.
6 Classification of steel names
For the purpose of designation, steel names are classified into two main groups.

— Group 1: Steels designated according to their application and mechanical or physical properties.

See 7.2.

— Group 2: Steels designated according to their chemical composition and further divided into four

sub-groups. See 7.3.
7 Structure of steel names
7.1 Initial symbol for steel castings

Where a steel is specified in the form of a steel casting, its steel name as specified in 7.2 and 7.3 shall be

preceded by the letter G.
7.2 Steels designated according to their application and mechanical or physical
properties (group 1)
The coding shall comprise the following principal symbols.
a) S = structural steels.
P = steels for pressure purposes.
L = steels for linepipe.
E = engineering steels.

Each followed by a number being the specified minimum yield strength in MPa for the smallest

thickness range.

NOTE 1 The term “yield strength” as used in this document refers to upper or lower yield strength, R or

R , proof strength, R , or proof strength total extension, R , depending on the requirement specified in the

eL p t
relevant product standard.
NOTE 2 1 MPa = 1 N/mm .

When the specified minimum tensile strength is used instead of the specified minimum yield

strength, the letter T shall be added after the principal symbol, e.g. PT.

In order to distinguish structural steels of different regions an additional letter “G” may be added,

e.g. steel grade SG345, see ISO 630-2.
b) B = steels for reinforcing concrete.
Followed by a number being the characteristic yield streng
...

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