SIST EN ISO 14373:2015

SLOVENSKI STANDARD
SIST EN ISO 14373:2015
01-junij-2015
1DGRPHãþD
SIST EN ISO 14373:2007
8SRURYQRYDUMHQMH3RVWRSHNWRþNRYQHJDYDUMHQMDQHSUHYOHþHQLKLQSUHYOHþHQLK
PDORRJOMLþQLKMHNHO,62
Resistance welding - Procedure for spot welding of uncoated and coated low carbon
steels (ISO 14373:2015)
Widerstandsschweißen - Verfahren zum Punktschweißen von niedriglegierten Stählen
mit oder ohne metallischem Überzug (ISO 14373:2015)
Soudage par résistance - Mode opératoire pour le soudage par points des aciers à bas
carbone revêtus et non revêtus (ISO 14373:2015)
Ta slovenski standard je istoveten z: EN ISO 14373:2015
ICS:
25.160.10 Varilni postopki in varjenje Welding processes
SIST EN ISO 14373:2015 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 14373:2015

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SIST EN ISO 14373:2015

EUROPEAN STANDARD
EN ISO 14373

NORME EUROPÉENNE

EUROPÄISCHE NORM
March 2015
ICS 25.160.10 Supersedes EN ISO 14373:2007
English Version
Resistance welding - Procedure for spot welding of uncoated
and coated low carbon steels (ISO 14373:2015)
Soudage par résistance - Mode opératoire pour le soudage Widerstandsschweißen - Verfahren zum Punktschweißen
par points des aciers à bas carbone revêtus et non revêtus von niedriglegierten Stählen mit oder ohne metallischem
(ISO 14373:2015) Überzug (ISO 14373:2015)
This European Standard was approved by CEN on 3 January 2015.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14373:2015 E
worldwide for CEN national Members.

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SIST EN ISO 14373:2015
EN ISO 14373:2015 (E)
Contents Page
Foreword .3

2

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SIST EN ISO 14373:2015
EN ISO 14373:2015 (E)
Foreword
This document (EN ISO 14373:2015) has been prepared by IIW “International Institute of Welding“ in
collaboration with Technical Committee CEN/TC 121 “Welding” the secretariat of which is held by DIN.
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 2015, and conflicting national standards shall be
withdrawn at the latest by September 2015.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 14373:2007.
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, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 14373:2015 has been approved by CEN as EN ISO 14373:2015 without any modification.
3

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SIST EN ISO 14373:2015

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SIST EN ISO 14373:2015
INTERNATIONAL ISO
STANDARD 14373
Second edition
2015-03-15
Resistance welding — Procedure for
spot welding of uncoated and coated
low carbon steels
Soudage par résistance — Mode opératoire pour le soudage par
points des aciers à bas carbone revêtus et non revêtus
Reference number
ISO 14373:2015(E)
©
ISO 2015

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SIST EN ISO 14373:2015
ISO 14373:2015(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2015
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
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2015 – All rights reserved

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SIST EN ISO 14373:2015
ISO 14373:2015(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviated terms . 2
5 Materials . 3
5.1 Form . 3
5.2 Steel grades . 3
6 Surface conditions . 3
7 Edge conditions, form of component, and weld spacing . 3
8 Electrodes . 3
8.1 Materials . 3
8.2 Dimensions . 3
8.3 Cooling of electrodes . 5
9 Weld assessment . 6
9.1 General . 6
9.2 Weldability tests . 6
9.3 Production tests . 6
9.4 Frequency of testing . 6
10 Weld quality requirements . 7
10.1 Weld diameter . 7
10.2 Weld penetration and indentation . 7
10.3 Failure description of welds . 7
10.4 Tensile shear strength . 7
10.5 Weld appearance . 8
10.5.1 Surface condition . 8
10.5.2 Distortion . 8
11 Multi-weld arrays . 9
Annex A (informative) Recommendations for spot welding equipment .11
Annex B (informative) Typical spot welding conditions .12
Annex C (informative) Partial list of steel types applicable to this International Standard .14
Bibliography .15
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SIST EN ISO 14373:2015
ISO 14373:2015(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
ISO 14373 was prepared by IIW, International Institute of Welding, Commission III. Requests for official
interpretations of any aspect of this International Standard should be directed to the ISO Central
Secretariat, who will forward them to the IIW Secretariat for an official response.
This second edition cancels and replaces the first edition (ISO 14373:2006), which has been technically
revised to align it with ISO 17677-1.
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SIST EN ISO 14373:2015
ISO 14373:2015(E)

Introduction
This International Standard no longer includes figures showing failure types and modes for tensile shear
and cross tension testing in accordance with ISO 14329.
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SIST EN ISO 14373:2015

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SIST EN ISO 14373:2015
INTERNATIONAL STANDARD ISO 14373:2015(E)
Resistance welding — Procedure for spot welding of
uncoated and coated low carbon steels
1 Scope
This International Standard specifies requirements for resistance spot welding in the fabrication of
assemblies of uncoated and metallic coated low carbon steel, comprising two or three sheets of metal,
where the maximum single sheet thickness of components to be welded is within the range 0,4 mm to
3 mm, for the following materials:
— uncoated steels;
— hot-dip zinc or iron-zinc alloy (galvannealed) coated steel;
— electrolytic zinc, zinc-iron, or zinc-nickel coated steel;
— aluminium coated steel;
— zinc-aluminium coated steel.
This International Standard is applicable to welding of sheets of the same or dissimilar thickness, where
the thickness ratio is less than or equal to 3:1. It applies to the welding of three thicknesses, where the
total thickness is less than or equal to 9 mm.
Welding with the following types of equipment is within the scope of this International Standard:
a) pedestal welding equipment;
b) gun welders;
c) automatic welding equipment where the components are fed by robots or automatic feeding
equipment;
d) multi welders;
e) robotic welders.
Information on appropriate welding equipment is given in Annex A, and information on spot welding
conditions is given in Annex B. This information is provided for guidance only.
Depending on the service conditions of the fabrication, the type of welding equipment, the characteristics
of the secondary circuit, the electrode material, and the shape, it is possible that certain modifications
are necessary. In such cases, further information can be obtained from the relevant application standard,
where one exists.
The welding of organic coated or primer coated steels is not within the scope of this International
Standard.
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 5182, Resistance welding — Materials for electrodes and ancillary equipment
ISO 10447, Resistance welding — Peel and chisel testing of resistance spot and projection welds
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SIST EN ISO 14373:2015
ISO 14373:2015(E)

ISO 14270, Resistance welding — Specimen dimensions and procedure for mechanized peel testing resistance
spot, seam and embossed projection welds
ISO 15609-5, Specification and qualification of welding procedures for metallic materials — Welding
procedure specification — Part 5: Resistance welding
ISO 15614-12, Specification and qualification of welding procedures for metallic materials — Welding
procedure test — Part 12: Spot, seam and projection welding
ISO 17677-1, Resistance welding — Vocabulary — Part 1: Spot, projection and seam welding
ISO 18278-1, Resistance welding — Weldability — Part 1: Assessment of weldability for resistance spot,
seam and projection welding of metallic materials
ISO 18272-2, Resistance welding — Weldability — Part 2: Alternative procedures for the assessment of
sheet steels for spot welding
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 17677-1 and the following
apply.
3.1
cross-tension test
test to determine the load-carrying capability of a spot welded joint subjected to cross tension loading
3.2
tensile shear test
test to determine the load-carrying capability of a spot welded joint subjected to shear tension loading
3.3
weld nugget
lenticular zone in a resistance weld, where metal from both (all) sheets has melted and resolidified
3.4
weld pitch
centre-to-centre distance between adjacent spot welds
3.5
edge distance
distance from the edge of the component to the centre of a weld
4 Symbols and abbreviated terms
See Table 1.
Table 1 — Symbols and definitions
Symbol Term Dimension
d weld diameter (see ISO 17677-1) mm
w
d corona bond diameter mm
c
d electrode tip diameter mm
e
d nugget diameter mm
n
t sheet thickness mm
P tensile shear strength of a weld (TSS) kN
s
R ultimate tensile strength of steel being welded MPa
m
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SIST EN ISO 14373:2015
ISO 14373:2015(E)

5 Materials
5.1 Form
The steel shall be flat rolled, in coil or cut to length, and shall be free from harmful imperfections.
5.2 Steel grades
A partial list of steel grades to which this International Standard is applicable is given in Annex C.
6 Surface conditions
Prior to welding, all surfaces of components to be spot-welded shall be free from grease, scale, rust,
paint, dirt, or excessive pitting. Uncoated hot rolled steel shall be in the pickled condition. Coated steels
can be supplied with a chromate or phosphate passivation treatment. Phosphated mild steel may be
used in certain applications. These materials can be spot welded, although adjustment may be required
to the welding parameters outlined in Annex B. Generally speaking, only thin phosphate pretreatment
of steel is acceptable prior to spot welding.
NOTE Certain surface treatments, such as the application of paint primers, rust preventatives, and oils, can
be applied before welding, provided that the coating is uniform in thickness and it has been shown that consistent
welds conforming to this International Standard can be obtained. Excessive use of surface pretreatment reduces
the length of electrode life.
7 Edge conditions, form of component, and weld spacing
The components to be welded shall be free from any burrs or other defects which may interfere with
interface contact in some way, or which may necessitate excessive force in fitting the parts together.
The shape of the component should be such that there is satisfactory interfacial contact in the area
where the welds are to be made. The edge distance should not be less than 1,25 d (see Figure 1), where
w
d is the weld diameter as defined in 8.2. The use of edge distances less than the recommended values
w
influences weld quality adversely. In such cases, the nominal weld size specified may be less than that
given in 8.2, and therefore due allowance is needed for a lower weld strength (see 10.4).
The distance between adjacent spot welds (see Figure 1) should not be less than 16 t, and preferably
greater. Tolerances for the distance between the centres of two adjacent spot welds should not exceed
±10 %, provided that it does not fall below the minimum value.
8 Electrodes
8.1 Materials
The electrode materials shall be a copper alloy and should possess high thermal and electrical
conductivity. They should comply with, and be used in accordance with, ISO 5182.
8.2 Dimensions
The welding electrodes should be of sufficient cross sectional area and strength to carry the welding
current and electrode force without overheating, excessive deformation, or excessive deflection.
The electrode dimensions should conform to ISO 5184 for straight electrodes, ISO 5830 for male
electrode caps, and ISO 5821 for female electrode caps, as applicable.
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SIST EN ISO 14373:2015
ISO 14373:2015(E)

Key
d weld diameter
w
t sheet thickness
r corner radius
NOTE Corner radius r is recommended to be between one and three times of sheet thickness t.
Figure 1 — Recommended edge conditions and weld pitch
When welding two sheets of thickness of maximum 3 mm using truncated cone type electrodes, the
electrode tip diameter should be chosen from standard sizes according to Formula (1).
de = 5√t (1)
where
de is the initial tip diameter, in mm;
t is the thickness of the sheet in contact with the electrode, in mm.
When using truncated cone electrodes, the initial (or set-up) weld diameter should be equal to the
diameter of the electrode tip; i.e.
d = de = 5√t (2)
w
where
d is the weld diameter, in mm.
w
CAUTION — The use of a smaller weld size than that given by Formula (2) may result in lower
tensile shear strength (TSS). This needs to be taken into account in all design calculations (see
Table 2).
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SIST EN ISO 14373:2015
ISO 14373:2015(E)

When using domed electrodes with small tip radii or electrodes with very small working faces,
Formula (1) does not always apply, in which case the electrode dimensions depend on accessibility and
flange width. In such cases, the electrode tip dimensions and welding conditions are selected to give
a weld diameter as specified in Formula (2), and they meet the minimum requirements outlined in
Clause 10.
When welding two sheets of dissimilar thickness, the electrode dimensions and the required weld size
should be specified with reference to the thinner sheet thickness. In the case of three thicknesses, the
thinner sheet of each combination should be used as the reference.
Where a pad or mandrel is used as the second electrode, its surface shall be maintained to match the
profile of the work piece.
Table 2 — Typical minimum tensile shear strength values for low carbon steel
Nominal 3,5√t Nominal 4√t Nominal 5√t Nominal 6√t
Sheet
Weld Weld Weld Weld
Weld Weld Weld Weld
thickness
strength strength strength strength
diameter diameter diameter diameter
TSS TSS TSS TSS
mm mm kN mm kN mm kN mm kN
0,6 2,7 1,3 3,1 1,6 3,9 2,0 4,6 2,3
0,8 3,1 2,3 3,6 3,0 4,5 3,6 5,4 4,2
1,0 3,5 3,2 4,0 3,7 5,0 4,3 6,0 5,1
1,2 3,8 4,1 4,4 4,6 5,5 5,4 6,6 6,2
1,6 4,4 5,5 5,1 6,0 6,3 7,4 7,6 8,3
2,0 5,0 7,2 5,7 8,4 7,1 10,8 8,5 13,5
2,5 5,5 10,6 6,3 11,8 7,9 14,5 9,5 17,3
3,0 6,0 12,0 6,9 14,0 8,6 17,8 10,4 22,0
NOTE These values can be used for design calculations. Higher values are generally obtained in practice. Higher strengths
are also obtained with higher strength steels.
During normal production, electrodes tend to mushroom, leading to an increase in electrode tip
diameter. The diameter of at least one of the electrodes should not normally be allowed to increase
above a value which results in a reduction in weld size to less than the acceptable minimum, e.g. 3,5√t.
When this diameter has been reached (if not before), the electrode should be replaced or redressed to
its initial size and contour.
Where electrode tips of different diameters are in contact with the work, the permissible increase over
the initial diameter should apply to the smaller of the two electrode tips.
A greater increase in electrode tip diameter is permissible only if tests prove that the strength of the
weld does not fall below the desired requirements.
In cases where automatic weld current increase is used (i.e. stepper controls), the increase in electrode
tip diameter can be greater. The acceptable increase can be determined by empirical means, provided
that the weld size does not fall below that specified in Formula (2).
8.3 Cooling of electrodes
The bore of the cooling water hole and pipe should conform to ISO 5184, ISO 5830, or ISO 5821, whichever
is applicable.
It is recommended that the water flow be a minimum of 4 l/min per electrode for welding two uncoated
steel sheets of thickness up to and including 3,0 mm. Higher flow rates are recommended when welding
coated steels. The internal water-cooling feed tube should be arranged to ensure that the water impinges
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SIST EN ISO 14373:2015
ISO 14373:2015(E)

onto the back working face of the electrode. The distance between the back and the working face of the
electrode should not exceed the values given in the relevant International Standard.
9 Weld assessment
9.1 General
A procedure shall be established in accordance with ISO 15609-5 for the welding equipment, sheet
thickness, material, or combinations thereof, used in the component being welded. The procedure shall
be qualified in accordance with ISO 15614-12.
9.2 Weldability tests
The weldability of a particular steel can be assessed by determining weldability lobes and the electrode
life in accordance with ISO 18278-1 and ISO 18278-2. These tests are also used to assess whether a
particular set of welding equipment is suitable for producing a specific components.
Guidelines for the welding equipment and welding conditions are given in Annexes A and B.
9.3 Production tests
The following tests shall be carried out to ensure consistent spot weld quality under production
conditions:
a) a visual examination, in accordance with Clause 10;
b) either a peel or chisel test (manual or mechanized), in accordance with ISO 10447 or ISO 14270.
Alternatively, other equivalent non-destructive tests may be used.
In addition, other tests, such as tensile shear tests, may be carried out.
9.4 Frequency of testing
When practicable, actual components shall be used for testing. When it is not practicable to use actual
components, test pieces of the same material with relevant flange widths shall be used, and there shall
be sufficient material associated with the test piece in the throat of the machine to approximate the
magnetic effect of the work piece under production conditions.
Tests should be carried out on each of the following occasions:
a) at the beginning of each shift or daily work period;
b) immediately before and after new or reconditioned electrodes are fitted to the machine;
c) whenever any of the following occurs: major maintenance, repairs, change in key machine
components, or machine settings;
d) immediately following a change of supply sources for materials or components to be welded.
Manufacturing shall not start until a satisfactory test weld has been obtained at the beginning of each
period specified above. In the event of the test piece failing at the end of the shift or work period, 2 % or
10 pieces (whichever is greater) shall be selected from the production during the period following the
previous test on that machine, and they shall be tested in accordance with Clause 10. In the event of any
of the selected
...