EN ISO 18595:2007

SLOVENSKI STANDARD
01-april-2008
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Resistance welding - Spot welding of aluminium and aluminium alloys - Weldability,
welding and testing (ISO 18595:2007)
Widerstandsschweißen - Punktschweißen von Aluminium und Aluminiumlegierungen -
Schweißeignung, Schweißen und Prüfungen (ISO 18595:2007)
Soudage par résistance - Soudage par points de l'aluminium et des alliages d'aluminium
- Soudabilité, soudage et essais (ISO 18595:2007)
Ta slovenski standard je istoveten z: EN ISO 18595:2007
ICS:
25.160.10 Varilni postopki in varjenje Welding processes
77.120.10 Aluminij in aluminijeve zlitine Aluminium and aluminium
alloys
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 18595
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2007
ICS 25.160.10
English Version
Resistance welding - Spot welding of aluminium and aluminium
alloys - Weldability, welding and testing (ISO 18595:2007)
Soudage par résistance - Soudage par points de Widerstandsschweißen - Punktschweißen von Aluminium
l'aluminium et des alliages d'aluminium - Soudabilité, und Aluminiumlegierungen - Schweißeignung, Schweißen
soudage et essais (ISO 18595:2007) und Prüfungen (ISO 18595:2007)
This European Standard was approved by CEN on 8 August 2007.
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 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 Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 18595:2007: E
worldwide for CEN national Members.

Contents Page
Foreword.3

Foreword
This document (EN ISO 18595:2007) has been prepared by Technical Committee ISO/TC 44 "Welding and
allied processes" 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 March 2008, and conflicting national standards shall be withdrawn at
the latest by March 2008.
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, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 18595:2007 has been approved by CEN as a EN ISO 18595:2007 without any modification.

INTERNATIONAL ISO
STANDARD 18595
First edition
2007-09-01
Resistance welding — Spot welding of
aluminium and aluminium alloys —
Weldability, welding and testing
Soudage par résistance — Soudage par points de l'aluminium et des
alliages d'aluminium — Soudabilité, soudage et essais

Reference number
ISO 18595:2007(E)
©
ISO 2007
ISO 18595:2007(E)
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ii © ISO 2007 – All rights reserved

ISO 18595:2007(E)
Contents Page
Foreword. iv
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 2
4 Symbols. 5
5 Material. 6
5.1 Form. 6
5.2 Types of aluminium alloys. 6
6 Surface conditions. 6
7 Edge distance, edge conditions, form of component and weld spacing. 6
8 Electrodes. 7
8.1 Materials. 7
8.2 Dimensions. 7
8.3 Cooling electrodes. 9
9 Weld assessment. 9
9.1 General. 9
9.2 Weldability test procedure. 9
9.3 Procedure qualification tests . 10
9.4 Production tests. 11
9.5 Frequency of testing. 11
10 Weld quality requirements. 11
10.1 Weld diameter. 11
10.2 Weld dimensions . 12
10.3 Weld fracture mode . 12
10.4 Weld strength. 12
10.5 Weld appearance — Surface condition . 12
11 Multi-weld arrays. 13
Annex A (informative) Recommendations for spot welding equipment. 15
Annex B (informative) Typical spot welding conditions . 16
Annex C (informative) Non-exhaustive list of aluminium alloys covered by this International
Standard . 17
Annex D (informative) Typical information to appear on a welding procedure sheet for spot
welding. 19
Bibliography . 21

ISO 18595:2007(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 18595 was prepared by Technical Committee ISO/TC 44, Welding and allied processes, Subcommittee
SC 6, Resistance welding.
Requests for official interpretations of any aspect of this International Standard should be directed to the
Secretariat of ISO/TC 44/SC 6 via your national standards body, a complete listing of which can be found at
www.iso.org.
iv © ISO 2007 – All rights reserved

INTERNATIONAL STANDARD ISO 18595:2007(E)

Resistance welding — Spot welding of aluminium and
aluminium alloys — Weldability, welding and testing
1 Scope
This International Standard specifies requirements for resistance spot welding in the fabrication of assemblies
of aluminium sheet, extrusions (both work- and age-hardening alloys) and/or cast material comprising two or
three thicknesses of metal, where the maximum single (sheet) thickness of components to be welded is within
the range 0,6 mm to 6 mm.
This International Standard is applicable to the welding of sheets or plates of 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 machines is within the scope of this International Standard:
⎯ pedestal welding machines;
⎯ gun welders;
⎯ automatic welding equipment where the components are fed by robots or automatic feeding equipment;
⎯ multi-welders;
⎯ robotic welders.
Information on appropriate welding equipment is given in Annex A and on spot welding conditions in Annex B.
The latter are for guidance only and may require modification depending on service conditions of the
fabrication, type of welding equipment, characteristics of the secondary circuit, electrode material and
geometry.
The welding of coated material, e.g. zinc-coated or anodised material, is not within the scope of this
International Standard.
2 Normative references
The following referenced documents are indispensable for the application 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 669:2000, Resistance welding — Resistance welding equipment — Mechanical and electrical
requirements
ISO 5182, Welding — Materials for resistance welding electrodes and ancillary equipment
ISO 5184, Straight resistance spot welding electrodes
ISO 5821, Resistance spot welding electrode caps
ISO 18595:2007(E)
ISO 5830, Resistance spot welding — Male electrode caps
ISO 10447, Resistance welding — Peel and chisel testing of resistance spot and projection welds
ISO 14329:2003, Resistance welding — Destructive tests of welds — Failure types and geometric
measurements for resistance spot, seam, and projection welds
ISO 15614-12, Specification and qualification of welding procedures for metallic materials — Welding
procedure test — Part 12: Spot, seam and projection welding
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 669:2000 and ISO 14329:2003 and
the following apply.
3.1
corona bond zone
zone outside the weld nugget in which solid phase bonding has occurred
NOTE 1 See Figure 1.
NOTE 2 This zone can contribute towards the strength of the joints but may not be considered for design purposes.
3.2
corona bond diameter
d
c
outer diameter of the corona bond zone
NOTE See Figure 1.
3.3
cross-tension test
test to determine the load-carrying behaviour of a spot-welded joint subjected to cross-tension loading
3.4
interface failure
fracture through the weld nugget between the sheets in the plane of the interface
NOTE See Figure 1.
3.5
nugget diameter
d
n
mean of the maximum and minimum diameters of the fused nugget in the plane of the interface between the
pieces joined, measured on a metallographic section taken transversely through the centre of the nugget
NOTE See Figure 1. The nugget diameter is the parameter on which the mechanical behaviour of a structure is
based. Other parameters such as the plug or weld diameter can be influenced by the type of destructive test.
3.6
plug failure
slug/button failure
fracture in the base metal, the heat-affected zone, or the nugget leaving attached metal pulled through
thickness from the opposing sheet
NOTE See Figure 2.
2 © ISO 2007 – All rights reserved

ISO 18595:2007(E)
3.7
partial plug failure
fracture partly in the base material or the heat-affected zone and partly in the nugget leaving attached metal
pulled through thickness from the opposing sheet
NOTE See Figure 2.
3.8
shear test
tensile shear test
test to determine the load-carrying behaviour of a spot-welded joint subjected to shear tension loading
3.9
weld diameter
d
〈in an interface failure〉 mean diameter of the fused zone measured at the interface omitting the corona bond
3.10
weld diameter
d
〈in a plug failure〉 mean diameter of the plug
NOTE See Figure 2 a) and b).
3.11
weld diameter
d
〈in a partial plug failure〉 mean diameter of the fused zone measured at the interface, omitting the corona bond
area and the maximum diameter of the plug component of the failure
NOTE 1 See Figure 2 c).
NOTE 2 The minimum diameter of the plug component of the fracture is reported separately (see Figures 1 and 2).
NOTE 3 The plug diameter in aluminium spot welds is generally less than or equal to the diameter of the (weld) nugget.
3.12
weld nugget
lenticular zone in a resistance weld where metal from both (all) sheets has melted and resolidified
3.13
plug diameter
d
p
mean diameter of the plug in both plug and partial plug failure modes
NOTE See Figure 2.
ISO 18595:2007(E)
Key
a
1 weld with interfacial fracture (d ≈ d ) Corona bond diameter.
n
b
2 corona bond zone Nugget diameter.
c
3 molten material of the nugget Weld diameter (d or d ).
1 2
4 rough fracture zone
Figure 1 — Measurement of weld size — Weld with interface failure

a
a)  Symmetrical plug failure
a
b)  Asymmetrical plug failure

4 © ISO 2007 – All rights reserved

ISO 18595:2007(E)
b
c)  Partial plug failure
a
d = d = (d + d )/2
p 1 2
b
d = (d + d )/2 and d = (d + d )/2
1 2 p 2 3
Figure 2 — Measurement of weld size — Weld with plug (slug) failure
4 Symbols
Symbol Term Unit
d weld diameter mm
d corona bond diameter mm
c
d initial or set-up weld diameter mm
i
d nugget diameter mm
n
d plug diameter mm
p
d initial electrode tip diameter mm
t
t sheet thickness mm
P shear strength of weld kN
s
R ultimate strength of aluminium being welded MPa
m
ISO 18595:2007(E)
5 Material
5.1 Form
The material shall be flat rolled, extruded or cast and shall be free from harmful imperfections.
5.2 Types of aluminium alloys
A partial list of aluminium alloys is given in Annex C.
6 Surface conditions
Prior to welding, all surfaces shall be checked for their suitability for spot welding. The surfaces should be free
from oil, grease, lubricant, visible oxidation, paint, dirt, or excessive scratches. If necessary, appropriate
surface treatment, e.g. chemical etching, shall be carried out. Mill-finish surfaces are generally not suitable for
spot welding; however, aluminium manufacturers can supply surface-treated material suitable for spot welding,
e.g. with TiZr conversion coating. Extrusions shall also be in the mill-finish condition and will generally require
pre-treatment. Die-cast material shall be free from excessive surface roughness and imperfections, e.g. as
caused by washing out of the die material. Excessive quantities of dissolved gases in die-cast material shall
be avoided. In addition, coated material can be supplied with chromate or phosphate passivation. Phosphated
aluminium may be used in certain applications. These materials can be spot welded, although adjustment to
the welding parameters will generally be necessary as outlined in Annex B.
NOTE In most countries, chromate passivation treatment will be prohibited in the near future to avoid health risks.
7 Edge distance, edge conditions, form of component and weld spacing
The components to be welded shall be free from burrs or other defects, which may, in any way, interfere with
interface contact or require excessive force to fit the parts together.
The shape of the component shall be such that there is satisfactory interfacial contact in the area where welds
are to be made. The distance from the edge of the component to the centre of the weld (edge distance) shall
be not less than 1,25d (see Figure 3), where d is the initial weld diameter as defined in 8.2. The use of edge
distances lower than the recommended values will adversely influence weld quality. Edge distances lower
than the recommended values should be used only when expressly specified. In this case the nominal weld
size specified may be less than that given in 8.2, and therefore due allowance needs to be made for a lower
weld strength (see 10.4).
The weld pitch, i.e. the centre-to-centre distance between adjacent spot welds (see Figure 3), shall not be less
than 6d and preferably larger. Tolerances for distances between the centres of two adjacent spot welds should
not exceed ± 10 % provided that the pitch does not fall below the minimum value. Smaller weld pitches may
be specified provided that the current is increased after the first weld to compensate for the effect of shunting
and the required weld quality can be achieved.
NOTE In the case of aluminium alloys, the shunting effect is much greater due to the higher electrical conductivity as
compared to steel.
6 © ISO 2007 – All rights reserved

ISO 18595:2007(E)
Key
d weld diameter
Figure 3 — Recommended edge distance and weld pitch
8 Electrodes
8.1 Materials
The electrode materials shall be copper alloy and should possess high thermal and electrical conductivity and
shall comply with, and be used in accordance with ISO 5182.
8.2 Dimensions
The welding electrodes shall be of sufficient cross-sectional area and strength to carry the welding current and
electrode force without overheating, excessive deformation, or excessive deflection. If possible, from the point
of accessibility, electrodes with a minimum diameter, D, of 20 mm should be used.
The electrode dimensions shall, where practicable, conform to ISO 5184 for straight electrodes, ISO 5821 for
female electrode caps, or ISO 5830 for male electrode caps, as applicable. In cases where these standards
do not apply, the dimensions of the electrode shall be specified such that welds conforming to this
International Standard are produced.
When welding two sheets of thickness up to 3 mm using truncated cone-type electrodes, the initial electrode
tip diameter, d , in millimetres, shall be chosen according to the following equation unless otherwise specified:
t
dt=+62 (1)
t
where t is the thickness, in millimetres, of the sheet in contact with the electrode.
When using truncated cone electrodes, the initial or set-up weld diameter, d , in millimetres, should be greater
i
than or equal to the diameter of the electrode tip, in accordance with Expression (2):
ddW=+62
...