SIST EN ISO 26304:2025

SLOVENSKI STANDARD
01-november-2025
Nadomešča:
SIST EN ISO 26304:2018
Dodajni in pomožni materiali za varjenje - Masivne žične elektrode, strženske žice
in kombinacije žic in praškov za obločno varjenje pod praškom za visokotrdnostna
jekla - Razvrstitev (ISO 26304:2025)
Welding consumables - Solid wire electrodes, tubular cored electrodes and electrode-
flux combinations for submerged arc welding of high strength steels - Classification (ISO
26304:2025)
Schweißzusätze - Massivdrahtelektroden, Fülldrahtelektroden und Draht-Pulver-
Kombinationen zum Unterpulverschweißen von hochfesten Stählen - Einteilung (ISO
26304:2025)
Produits consommables pour le soudage - Fils-électrodes pleins, fils-électrodes fourrés
et couples électrodes-flux pour le soudage à l'arc sous flux des aciers à haute résistance
- Classification (ISO 26304:2025)
Ta slovenski standard je istoveten z: EN ISO 26304:2025
ICS:
25.160.20 Potrošni material pri varjenju Welding consumables
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 26304
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2025
EUROPÄISCHE NORM
ICS 25.160.20 Supersedes EN ISO 26304:2018
English Version
Welding consumables - Solid wire electrodes, tubular
cored electrodes and electrode-flux combinations for
submerged arc welding of high strength steels -
Classification (ISO 26304:2025)
Produits consommables pour le soudage - Fils- Schweißzusätze - Massivdrahtelektroden,
électrodes pleins, fils-électrodes fourrés et couples Fülldrahtelektroden und Draht-Pulver-Kombinationen
électrodes-flux pour le soudage à l'arc sous flux des zum Unterpulverschweißen von hochfesten Stählen -
aciers à haute résistance - Classification (ISO Einteilung (ISO 26304:2025)
26304:2025)
This European Standard was approved by CEN on 20 August 2024.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 26304:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 26304:2025) has been prepared by Technical Committee ISO/TC 44 "Welding
and allied processes" in collaboration with Technical Committee CEN/TC 121 “Welding and allied
processes” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by September 2025, and conflicting national standards
shall be withdrawn at the latest by September 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 26304:2018.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 26304:2025 has been approved by CEN as EN ISO 26304:2025 without any modification.

International
Standard
ISO 26304
Fourth edition
Welding consumables — Solid wire
2025-03
electrodes, tubular cored electrodes
and electrode-flux combinations
for submerged arc welding of high
strength steels — Classification
Produits consommables pour le soudage — Fils-électrodes pleins,
fils-électrodes fourrés et couples électrodes-flux pour le soudage à
l'arc sous flux des aciers à haute résistance — Classification
Reference number
ISO 26304:2025(en) © ISO 2025
ISO 26304:2025(en)
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
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or ISO’s member body in the country of the requester.
ISO copyright office
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CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 26304:2025(en)
Contents Page
Foreword .iv
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Classification . 2
4.1 General .2
4.2 Classification systems .2
5 Symbols and requirements . 3
5.1 General .3
5.2 Symbol for the product or process .3
5.3 Symbols for the tensile properties of the all-weld metal deposit.4
5.3.1 Multi-run technique . .4
5.3.2 Two-run technique – system B only .5
5.4 Symbol for the impact properties of the multi-run or two-run technique .5
5.5 Symbol for the type of welding flux .6
5.6 Symbol for the chemical composition of solid wire electrodes and of the all-weld metal
from tubular cored electrode-flux combinations .6
5.7 Symbol for post-weld heat treatment . 12
5.8 Optional symbol for hydrogen content of deposited metal . 13
6 Mechanical tests . 14
6.1 Multi-run technique .14
6.1.2 Preheating and interpass temperature .14
6.1.3 Welding conditions and pass sequence . 15
6.2 Two-run technique – system B only .16
7 Chemical analysis . .16
8 Rounding procedure .16
9 Retests . 17
10 Technical delivery conditions . 17
11 Examples of designation . 17
11.1 General .17
11.2 Example 1 – Classification by yield strength and 47 J impact energy – system A .17
11.3 Example 2 – Classification by tensile strength and 27 J impact energy – system B .18
11.4 Example 3 – Classification by yield strength and 47 J impact energy – system A .18
11.5 Example 4 – Classification by tensile strength and 27 J impact energy – system B .18
11.6 Example 5 – Classification by yield strength and 47 J impact energy – system A .18
11.7 Example 6 – Classification by tensile strength and 27 J impact energy – system B .18
11.8 Example 7 – Classification by yield strength and 47 J impact energy – system A .19
11.9 Example 8 – Classification by tensile strength and 47 J impact energy – system B .19
Annex A (informative) Possible risk of weld metal hydrogen cracking .20
Bibliography .21

iii
ISO 26304:2025(en)
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, 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 www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 44, Welding and allied processes, Subcommittee
SC 3, Welding consumables, in collaboration with the European Committee for Standardization (CEN)
Technical Committee CEN/TC 121, Welding and allied processes, in accordance with the Agreement on
technical cooperation between ISO and CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 26304:2017), which has been technically
revised.
The main changes are as follows:
— this document has been reformatted in single column showing System A and System B in tables and
separate clauses and subclauses, some which are new;
— a new paragraph has been added to the end of Clause 1, Scope;
— normative references updated;
— Table 1 was updated;
— Table 3 values for System B were revised to reflect those in ISO 18275 and ISO 18276
— Table 7 and Table 8 were revised and new footnotes added; header of the last column was revised;
— Table 11, H8 was added;
— Table 12, System B was revised;
— Subclause 5.3 was revised;
— Subclause 6.2 was revised;
— Clause 11, examples updated and expanded.

iv
ISO 26304:2025(en)
Any feedback or questions on this document should be directed to the user’s
national standards body. A complete listing of these bodies can be found at
www.iso.org/members.html. Official interpretations of ISO/TC 44 documents, where they exist, are
available from this page: https://committee.iso.org/sites/tc44/home/interpretation.html.

v
ISO 26304:2025(en)
Introduction
This document recognizes that there are two somewhat different approaches in the global market to classifying
a given solid wire electrode, tubular cored electrode, and electrode-flux combination, and allows for either or
both to be used, to suit a particular market need. Application of either type of classification designation (or
of both where suitable) identifies a product as classified in accordance with this document. The classification
in accordance with system A was originally based on EN 14295 which has been withdrawn and replaced by
this document. The classification in accordance with system B is mainly based on standards used around the
Pacific Rim. Future revisions aim to merge the two approaches into a single classification system.
This document provides a classification for the designation of solid wire electrodes in terms of their
chemical composition, tubular cored electrodes in terms of the deposit composition obtained with a
particular submerged arc flux, and, where required, electrode-flux combinations in terms of the yield
strength, tensile strength, elongation, and impact properties of the all-weld metal deposit. The ratio of yield
to tensile strength of weld metal is generally higher than that of parent material. Users should note that
matching weld metal yield strength to parent metal yield strength does not necessarily ensure that the weld
metal tensile strength matches that of the parent material. Thus, where the application requires matching
tensile strength, selection of the consumable should be made by reference to columns 3 or 6 of Table 3, as
appropriate.
Although combinations of electrodes and fluxes supplied by individual companies can have the same system
A classification, it is possible that the combination of an electrode with a flux from one manufacturer and the
same electrode with a flux from another manufacturer, both fluxes having the same classification, may not
be interchangeable unless verified in accordance with this document. Two tubular cored wires of the same
classification can likewise produce different results with the same flux.
The mechanical properties of the all-weld metal test specimens used to classify the electrode-flux
combinations vary from those obtained in production joints because of differences in welding procedures
such as electrode size, width of weave, welding position, and material composition.

vi
International Standard ISO 26304:2025(en)
Welding consumables — Solid wire electrodes, tubular cored
electrodes and electrode-flux combinations for submerged
arc welding of high strength steels — Classification
1 Scope
This document specifies requirements for classification of solid wire electrodes, tubular cored electrodes,
and electrode-flux combinations (the all-weld metal deposits) in the as-welded condition and in the post-
weld heat-treated condition for submerged arc welding of high strength steels with a minimum yield
strength greater than 500 MPa or a minimum tensile strength greater than 570 MPa. One flux can be tested
and classified with different electrodes. One electrode can be tested and classified with different fluxes. The
solid wire electrode is also classified separately based on its chemical composition.
This document is a combined specification providing for classification utilizing a system based on the yield
strength and average impact energy of 47 J for the all-weld metal, or utilizing a system based on the tensile
strength and average impact energy of 27 J for the all-weld metal.
a) Clauses, subclauses and tables which carry the suffix “system A” are applicable only to solid wire
electrodes, tubular cored electrodes and the all-weld metal deposits classified to the system based on
the yield strength and the average impact energy of 47 J for the all-weld metal obtained with electrode-
flux combinations in accordance with this document.
b) Clauses, subclauses and tables which carry the suffix “system B” are applicable only to solid wire
electrodes, tubular cored electrodes and the all-weld metal deposits classified to the system based on
the tensile strength and the average impact energy of 27 J for the all-weld metal obtained with electrode-
flux combinations in accordance with this document.
c) Clauses, subclauses and tables which do not have either the suffix “system A” or “system B” are applicable
to all solid wire electrodes, tubular cored electrodes and electrode-flux combinations classified in
accordance with this document.
For comparison purposes, some tables include requirements for electrodes classified in accordance with
both systems, placing individual electrodes from the two systems, which are similar in composition and
properties, on adjacent lines in the particular table. In a particular line of the table that is mandatory in
one system, the symbol for the similar electrode from the other system is indicated in parentheses. By
appropriate restriction of the formulation of a particular electrode, it is often, but not always, possible to
produce an electrode that can be classified in both systems, in which case the electrode, or its packaging,
can be marked with the classification in either or both systems.
For system B only, electrode flux combinations for the single-run and two-run techniques are classified on
the basis of the two-run technique.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 544, Welding consumables — Technical delivery conditions for filler materials and fluxes — Type of product,
dimensions, tolerances and markings
ISO 3690, Welding and allied processes — Determination of hydrogen content in arc weld metal

ISO 26304:2025(en)
ISO 6847, Welding consumables — Deposition of a weld metal pad for chemical analysis
ISO 13916, Welding — Guidance on the measurement of preheating temperature, interpass temperature and
preheat maintenance temperature
ISO 14174, Welding consumables — Fluxes for submerged arc welding and electroslag welding — Classification
ISO 14344, Welding consumables — Procurement of filler materials and fluxes
ISO 15792-1:2020, Welding consumables — Test methods — Part 1: Preparation of all-weld metal test pieces
and specimens in steel, nickel and nickel alloys
ISO 15792-2:2020, Welding consumables — Test methods — Part 2: Preparation of single-run and two-run
technique test pieces and specimens in steel
ISO 80000-1:2022, Quantities and units — Part 1: General
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Classification
4.1 General
Classification designations are based on two approaches to indicate the tensile properties and the impact
properties of the all-weld metal obtained with a given electrode-flux combination. The two designation
approaches include additional designators for the chemical composition of a solid wire electrode or
the chemical composition of the all-weld metal deposit obtained with a tubular cored electrode and a
specific flux. The two designation approaches include additional designators for some other classification
requirements, but not all, as is clear from the following clauses. A given commercial product may be classified
to the classification requirements in both systems; then either or both classification designations may be
used for the product.
The classification includes the all-weld metal properties obtained with a specific electrode-flux combination
as given in 4.2.
A solid wire electrode shall be classified in accordance with its chemical composition in Table 7.
A tubular cored electrode shall be classified in accordance with the all-weld metal deposit composition in
Table 8, obtained with a specific flux.
When the solid wire electrode or tubular cored electrode is classified in combination with a flux for
submerged arc welding, the classification shall be prefixed with a symbol in accordance with Clause 5 as
appropriate.
4.2 Classification systems
Each classification system, A and B, is split into parts as given in Table 1.

ISO 26304:2025(en)
Table 1 — Parts of the classification systems, A and B
Classification system
Part of classifi-
System A System B
cation designa-
Classification by yield strength and 47 J im- Classification by tensile strength and 27 J
tion
pact energy impact energy
1 symbol indicating the product or process to be identified
symbol indicating the strength and elongation symbol indicating the strength and elongation of
of all-weld metal for multi-run technique (see all-weld metal, and whether it was tested in the
Table 3). as-welded or post-weld heat-treated condition.
The symbol also indicates whether the weld
metal was deposited in the multi-run or two-run
technique. (see Table 3 and Table 4).
symbol indicating the impact properties of the symbol indicating the impact properties of
all-weld metal (see Table 5). the all-weld metal or welded joint in the same
condition as specified for the tensile strength
3 (see Table 5). The letter “U” after this designa-
tor indicates that the deposit meets an average
optional requirement of 47 J at the designated
impact test temperature;
symbol indicating the type of flux used (see 5.5). symbol indicating the chemical composition of
the solid wire electrode used (see Table 7), or of
the all-weld metal deposited by a tubular cored
electrode-flux combination (see Table 8);
symbol indicating the chemical composition of optional symbol indicating the diffusible hy-
the solid wire electrode used (see Table 7) or of drogen content of the weld metal determined in
the all-weld metal deposited by a tubular cored accordance with ISO 3690.
electrode-flux combination (see Table 8).
symbol indicating the postweld heat treatment
6 —
if this is applied.
optional symbol indicating the diffusible hy-
7 drogen content of the weld metal determined in —
accordance with ISO 3690.
5 Symbols and requirements
5.1 General
A solid wire electrode can be classified separately based on its chemical composition, as specified in
Table 7. The all-weld metal deposit composition and mechanical properties obtained with a particular
solid wire electrode or tubular cored electrode vary somewhat depending on the flux used. Accordingly,
the classification of the all-weld metal deposit obtained with a particular solid wire electrode or tubular
cored electrode can be different for different fluxes. However, deposit composition is only a classification
requirement for tubular cored electrode-flux combinations.
5.2 Symbol for the product or process
The symbol for the electrode-flux combination or weld deposit produced by a solid wire electrode or by a
tubular cored electrode using the submerged arc welding process with a specific flux, shall be the letter “S”
placed at the beginning of the designation.
The additional symbols in Table 2 shall be applied respectively to system A and system B

ISO 26304:2025(en)
Table 2 — Additional symbols for product or process
System A System B
Classification by yield strength and 47 J impact en- Classification by tensile strength and 27 J impact
ergy energy
The symbol for the solid wire electrode for use in the The symbol for the solid wire electrode for use in the
submerged arc welding process shall be the letter “S” submerged arc welding process shall be the letters “SU”
placed at the beginning of the solid wire electrode desig- placed at the beginning of the solid wire electrode desig-
nation. nation.
The symbol for the tubular cored electrode for use in the The symbol for the tubular cored electrode for use in the
submerged arc welding process shall be the letter “T” submerged arc welding process shall be the letters “TU”
placed at the beginning of the tubular cored electrode placed at the beginning of the tubular cored electrode
designation. designation.
5.3 Symbols for the tensile properties of the all-weld metal deposit
5.3.1 Multi-run technique
The symbols in Table 3 indicate:
a) System A – the yield strength, tensile strength, and elongation of the all-weld metal in the as-welded
condition or in the post-weld heat treated condition in accordance with Table 3, and 5.7 determined in
accordance with Clause 6
b) System B – the tensile strength, yield strength, and elongation of the all-weld metal in the as-welded
condition or in the post-weld heat-treated condition in accordance with Table 3, and 5.7 determined in
accordance with Clause 6
Table 3 — Symbols for the tensile properties of the all-weld metal deposit – multi-run technique
System A System B
Symbol for the tensile Symbol for the tensile
properties by multi-run technique(Classification by properties by multi-run technique (Classification by
yield strength and 47 J impact energy) tensile strength and 27 J impact energy)
a
Minimum Minimum
b
Tensile Minimum Tensile Minimum
a c
Symbol yield Symbol yield
b
strength elongation strength elongation
d
strength strength
MPa MPa % MPa MPa %
55 550 640 to 820 18 59X 590 to 790 490 16
62 620 700 to 890 18 62X 620 to 820 530 15
69 690 770 to 940 17 69X 690 to 890 600 14
79 790 880 to 1 080 16 76X 760 to 960 670 13
89 890 940 to 1 180 15 78X 780 to 980 690 13
83X 830 to 1 030 740 12
a
For yield strength, the lower yield strength, R , is used when yielding occurs, otherwise the 0,2 % proof strength, R , is
eL p0,2
used.
b
Gauge length is equal to five times the test specimen diameter.
c
X is “A” or “P”, where “A” indicates testing in the as-welded condition and “P” indicates testing in the post-weld heat-treated
condition.
d
For yield strength, the 0,2 % proof strength, R , is used.
p0,2
ISO 26304:2025(en)
5.3.2 Two-run technique – system B only
For products suitable for two-run welding, the symbols in Table 4 indicate the minimum tensile strength of
the weld metal from two-run welding tests satisfactorily completed in accordance with 6.2.
NOTE The two-run technique is not applicable to system A as the 47 J impact energy requirement is difficult to
achieve.
Table 4 — Symbols for tensile properties by two-run technique
(Classification by tensile strength and 27 J impact energy) – System B
Minimum tensile strength
a
Symbol
of the weld metal
MPa
59TX 590
62TX 620
69TX 690
76TX 760
78TX 780
83TX 830
a
T indicates two run technique.
5.4 Symbol for the impact properties of the multi-run or two-run technique
The symbols in Table 5 indicate the temperature at which a minimum average impact energy of 47 J or 27 J is
achieved under the conditions given in Clause 6 in the as-welded condition or after post-weld heat treatment.
Table 5 — Symbol for the impact properties of the all-weld metal or welded joint
Temperature for minimum
a, b b
average impact energy of 47 J or 27 J
Symbol
°C
Z No requirements
a b
A or Y +20
0 0
2 –20
3 –30
4 –40
5 –50
6 –60
a
When classified in accordance with system A.
b
When classified in accordance with system B.
The test specimens shall be tested in accordance with Table 6.

ISO 26304:2025(en)
Table 6 — Testing of impact specimens
System A System B
Classification by yield strength and 47 J impact ener- Classification by tensile strength and 27 J impact
gy energy
Three test specimens shall be tested. Five test specimens shall be tested
The average value shall be at least 47 J. Only one individu- The lowest and highest values obtained shall be dis-
al value may be lower than 47 J but not lower than 32 J. regarded. Two of the three remaining values shall be
greater than the specified 27 J level, one of the three may
be lower but shall not be less than 20 J. The average of the
three remaining values shall be at least 27 J.
The addition of the optional symbol U, after the symbol
for the impact designator indicates that the supplemental
requirement of 47 J impact energy at the normal 27 J im-
pact test temperature has also been satisfied. For the 47 J
impact requirement, the number of specimens tested and
values obtained shall meet the requirements of Table 6,
System A.
5.5 Symbol for the type of welding flux
The symbols for welding flux only for system A shall be in accordance with ISO 14174.
5.6 Symbol for the chemical composition of solid wire electrodes and of the all-weld metal
from tubular cored electrode-flux combinations
The symbols in Table 7 indicate the chemical composition of the solid wire electrode, determined under the
conditions given in Clause 7.
The symbols in Table 8 indicate the chemical composition of the all-weld metal deposit obtained with the
tubular cored electrode and a specific flux, determined under the conditions given in Clause 7.

ISO 26304:2025(en)
Table 7 — Chemical composition requirements for solid wire electrodes
Chemical composition
a
Symbol for chemical composition
b
% (by mass)
Classification by ten-
Classification by yield Other speci-
sile strength and 27 J
c
strength and 47 J impact C Si Mn P S Cr Ni Mo Cu V fied elements
impact energy
d
energy ISO 26304-A
ISO 26304-B
e, f
SUN1M3 0,10 to 0,18 0,20 1,70 to 2,40 0,025 0,025 — 0,40 to 0,80 0,40 to 0,65 0,35 — —
e, f
SUN2M1 0,12 0,05 to 0,30 1,20 to 1,60 0,020 0,020 — 0,75 to 1,25 0,10 to 0,30 0,35 — —
e, f
SUN2M3 0,15 0,25 0,80 to 1,40 0,020 0,020 0,20 0,80 to 1,20 0,40 to 0,65 0,40 — —
SUN2M11 0,07 to 0,15 0,05 to 0,30 1,20 to 1,60 0,020 0,020 — 0,75 to 1,25 0,10 to 0,30 0,35 — —
e, f
SUN2M31 0,15 0,25 1,30 to 1,90 0,020 0,020 0,20 0,80 to 1,20 0,40 to 0,65 0,40 — —
e, f
SUN2M32 0,15 0,25 1,60 to 2,30 0,020 0,020 0,20 0,80 to 1,20 0,40 to 0,65 0.40 — —
e, f
SUN2M33 0,10 to 0,18 0,30 1,50 to 2,40 0,025 0,025 — 0,70 to 1,10 0,40 to 0,65 0,35 — —
f, g
S2Ni1Mo (SUN2M2) 0,07 to 0,15 0,05 to 0,25 0,80 to 1,30 0,020 0,020 0,20 0,80 to 1,20 0,45 to 0,65 0,30 — —
f, g
S3Ni1Mo (SUN2M2) 0,07 to 0,15 0,05 to 0,35 1,30 to 1,80 0,020 0,020 0,20 0,80 to 1,20 0,45 to 0,65 0,30 — —
e
(S2Ni1Mo, S3Ni1Mo) SUN2M2 0,07 to 0,15 0,15 to 0,35 0,90 to 1,70 0,025 0,025 — 0,95 to 1,60 0,25 to 0,55 0,35 — —
f, g
S3Ni1,5Mo 0,07 to 0,15 0,05 to 0,25 1,20 to 1,80 0,020 0,020 0,20 1,20 to 1,80 0,30 to 0,50 0,30 — —
Ti: 0,10
e
SUN3M2 0,10 0,20 to 0,60 1,25 to 1,80 0,010 0,015 0,30 1,40 to 2,10 0,25 to 0,55 0,25 0,05 Zr: 0,10
Al: 0,10
e, f
SUN3M3 0,15 0,25 0,80 to 1,40 0,020 0,020 0,20 1,20 to 1,80 0,40 to 0,65 0,40 — —
e, f
SUN3M31 0,15 0,25 1,30 to 1,90 0,020 0,020 0,20 1,20 to 1,80 0,40 to 0,65 — — —
e
SUN4C1M31 0,07 to 0,15 0,10 to 0,30 1,45 to 1,90 0,015 0,015 0,20 to 0,55 1,75 to 2,25 0,40 to 0,65 0,35 — —
e, f
SUN4M1 0,12 to 0,19 0,10 to 0,30 0,60 to 1,00 0,015 0,020 0,20 1,60 to 2,10 0,10 to 0,30 0,35 — —
e
SUN4M3 0,15 0,25 1,30 to 1,90 — — — 1,80 to 2,40 0,40 to 0,65 0,40 — —
e
SUN4M31 0,15 0,25 1,60 to 2,30 — — — 1,80 to 2,40 0,40 to 0,65 0,40 — —
a
A designation in parentheses, e.g. (S2NiMo) or (SUN2M2), indicates a near match in the other designation system, but not an exact match. The correct designation for a given composition range is the one not in parentheses. A
given product may, by having a more restricted chemical composition which fulfils both sets of designation requirements, be assigned both designations independently.
b
Single values are maxima.
c
The copper limit includes any copper coating that may be applied to the electrode.
d
Analysis for B is required to be reported if intentionally added, or if it is known to be present at levels greater that 0,001 0 %.
e
The electrode shall be analysed for the specific elements for which values are shown. If the presence of other elements is indicated in the course of this work, the amount of those elements shall be determined to ensure that
their total (excluding iron) does not exceed 0,50 % (by mass).
f
This solid wire electrode composition, with a lower strength requirement, is also found in ISO 14171.
g
If not specified: Al, Sn, As and Sb ≤ 0,02 % (by mass) each and Ti, Pb and N ≤ 0,01 % (by mass) each.
h
Consumables for which the chemical composition is not listed shall be symbolized similarly and prefixed by the letters “SZ” under ISO 26304-A or simply “SUG” under ISO 26304-B. The chemical composition ranges are not
specified and it is possible that two electrodes with the same classification are not interchangeable.

ISO 26304:2025(en)
Table 7 (continued)
Chemical composition
a
Symbol for chemical composition
b
% (by mass)
Classification by ten-
Classification by yield Other speci-
sile strength and 27 J
c
strength and 47 J impact C Si Mn P S Cr Ni Mo Cu V fied elements
impact energy
d
energy ISO 26304-A
ISO 26304-B
Ti: 0,10
e
SUN4M2 0,10 0,20 to 0,60 1,40 to 1,80 0,010 0,015 0,55 1,90 to 2,60 0,25 to 0,65 0,25 0,04 Zr: 0,10
Al: 0,10
g
S2Ni2Mo 0,05 to 0,09 0,15 1,10 to 1,40 0,015 0,015 0,15 2,00 to 2,50 0,45 to 0,60 0,30 — —
Ti: 0,10
e
SUN5M3 0,10 0,20 to 0,60 1,40 to 1,80 0,010 0,015 0,60 2,00 to 2,80 0,30 to 0,65 0,25 0,03 Zr: 0,10
Al: 0,10
e
SUN5M4 0,15 0,25 1,60 to 2,30 — — 0,20 2,20 to 3,00 0,40 to 0,90 — — —
e
(S2Ni3Mo) SUN6M1 0,15 0,25 0,80 to 1,40 — — — 2,40 to 3,70 0,15 to 0,40 — — —
g
S2Ni3Mo (SUN6M1) 0,08 to 0,12 0,10 to 0,25 0,80 to 1,20 0,020 0,020 0,15 2,80 to 3,20 0,10 to 0,25 0,30 — —
e
SUN6M11 0,15 0,25 1,30 to 1,90 — — — 2,40 to 3,70 0,15 to 0,40 — — —
e
SUN6M3 0,15 0,25 0,80 to 1,40 — — — 2,40 to 3,70 0,40 to 0,65 — — —
e
SUN6M31 0,15 0,25 1,30 to 1,90 — — — 2,40 to 3,70 0,40 to 0,65 — — —
e
SUN1C1M1 0,16 to 0,23 0,15 to 0,35 0,60 to 0,90 0,025 0,030 0,40 to 0,60 0,40 to 0,80 0,15 to 0,30 0,35 — —
e
(S3Ni1,5CrMo) SUN2C1M3 0,15 0,40 1,30 to 2,30 — — 0,05 to 0,70 0,40 to 1,75 0,30 to 0,80 — — —
g
S3Ni1,5CrMo (SUN2C1M3) 0,07 to 0,14 0,05 to 0,15 1,30 to 1,50 0,020 0,020 0,15 to 0,35 1,50 to 1,70 0,30 to 0,50 0,30 — —
e
SUN2C2M3 0,15 0,40 1,00 to 2,30 — — 0,50 to 1,20 0,40 to 1,75 0,30 to 0,90 — — —
e
SUN4C2M3 0,15 0,40 1,20 to 1,90 — — 0,50 to 1,20 1,50 to 2,25 0,30 to 0,80 — — —
e
(S3Ni2,5CrMo) SUN4C1M3 0,15 0,40 1,20 to 1,90 0,018 0,018 0,20 to 0,65 1,50 to 2,25 0,30 to 0,80 0,40 — —
g
S3Ni2,5CrMo (SUN4C1M3) 0,07 to 0,15 0,10 to 0,25 1,20 to 1,80 0,020 0,020 0,30 to 0,85 2,00 to 2,60 0,40 to 0,70 0,30 — —
g
S1Ni2,5CrMo 0,07 to 0,15 0,10 to 0,25 0,45 to 0,75 0,020 0,020 0,50 to 0,85 2,10 to 2,60 0,40 to 0,70 0,30 — —
e
(S4Ni2CrMo) SUN5C2M3 0,10 0,40 1,30 to 2,30 — — 0,60 to 1,20 2,10 to 3,10 0,30 to 0,70 — — —
g
S4Ni2CrMo (SUN5C2M3) 0,08 to 0,11 0,30 to 0,40 1,80 to 2,00 0,015 0,015 0,85 to 1,00 2,10 to 2,60 0,55 to 0,70 0,30 — —
a
A designation in parentheses, e.g. (S2NiMo) or (SUN2M2), indicates a near match in the other designation system, but not an exact match. The correct designation for a given composition range is the one not in parentheses. A
given product may, by having a more restricted chemical composition which fulfils both sets of designation requirements, be assigned both designations independently.
b
Single values are maxima.
c
The copper limit includes any copper coating that may be applied to the electrode.
d
Analysis for B is required to be reported if intentionally added, or if it is known to be present at levels greater that 0,001 0 %.
e
The electrode shall be analysed for the specific elements for which values are shown. If the presence of other elements is indicated in the course of this work, the amount of those elements shall be determined to ensure that
their total (excluding iron) does not exceed 0,50 % (by mass).
f
This solid wire electrode composition, with a lower strength requirement, is also found in ISO 14171.
g
If not specified: Al, Sn, As and Sb ≤ 0,02 % (by mass) each and Ti, Pb and N ≤ 0,01 % (by mass) each.
h
Consumables for which the chemical composition is not listed shall be symbolized similarly and prefixed by the letters “SZ” under ISO 26304-A or simply “SUG” under ISO 26304-B. The chemical composition ranges are not
specified and it is possible that two electrodes with the same classification are not interchangeable.

ISO 26304:2025(en)
Table 7 (continued)
Chemical composition
a
Symbol for chemical composition
b
% (by mass)
Classification by ten-
Classification by yield Other speci-
sile strength and 27 J
c
strength and 47 J impact C Si Mn P S Cr Ni Mo Cu V fied elements
impact energy
d
energy ISO 26304-A
ISO 26304-B
e
SUN5CM3 0,10 to 0,17 0,20 1,70 to 2,20 0,010 0,015 0,25 to 0,50 2,30 to 2,80 0,45 to 0,65 0,50 — —
e
SUN7C3M3 0,08 to 0,18 0,40 0,20 to 1,20 — — 1,00 to 2,00 3,00 to 4,00 0,30 to 0,70 0,40 — —
e
SUN10C1M3 0,08 to 0,18 0,40 0,20 to 1,20 — — 0,30 to 0,70 4,50 to 5,50 0,30 to 0,70 0,40 — —
h h h
SZ SUG Any other agreed composition
a
A designation in parentheses, e.g. (S2NiMo) or (SUN2M2), indicates a near match in the other designation system, but not an exact match. The correct designation for a given composition range is the one not in parentheses. A
given product may, by having a more restricted chemical composition which fulfils both sets of
...