SIST EN ISO 7539-8:2008

SLOVENSKI STANDARD
01-julij-2008
Korozija kovin in zlitin - Preskušanje napetostne korozije - 8. del: Priprava in
uporaba preskušancev za ovrednotenje varjenih delov (ISO 7539-8:2000)
Corrosion of metals and alloys - Stress corrosion testing - Part 8: Preparation and use of
specimens to evaluate weldments (ISO 7539-8:2000)
Korrosion der Metalle und Legierungen - Prüfung der Spannungsrisskorrosion - Teil 8:
Vorbereitung und Anwendung von Proben zur Bewertung von Schweißverbindungen
(ISO 7539-8:2000)
Corrosion des métaux et alliages - Essais de corrosion sous contrainte - Partie 8:
Préparation et utilisation des éprouvettes pour évaluer les assemblages soudés (ISO
7539-8:2000)
Ta slovenski standard je istoveten z: EN ISO 7539-8:2008
ICS:
77.060 Korozija kovin Corrosion of metals
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 7539-8
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2008
ICS 77.060
English Version
Corrosion of metals and alloys - Stress corrosion testing - Part
8: Preparation and use of specimens to evaluate weldments
(ISO 7539-8:2000)
Corrosion des métaux et alliages - Essais de corrosion Korrosion der Metalle und Legierungen - Prüfung der
sous contrainte - Partie 8: Préparation et utilisation des Spannungsrisskorrosion - Teil 8: Vorbereitung und
éprouvettes pour évaluer les assemblages soudés (ISO Anwendung von Proben zur Bewertung von
7539-8:2000) Schweißverbindungen (ISO 7539-8:2000)
This European Standard was approved by CEN on 21 March 2008.
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.
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EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7539-8:2008: E
worldwide for CEN national Members.

Contents Page
Foreword.3

Foreword
The text of ISO 7539-8:2000 has been prepared by Technical Committee ISO/TC 156 “Corrosion of metals
and alloys” of the International Organization for Standardization (ISO) and has been taken over as EN ISO
7539-8:2008 by Technical Committee CEN/TC 262 “Metallic and other inorganic coatings” the secretariat of
which is held by BSI.
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 October 2008, and conflicting national standards shall be withdrawn at
the latest by October 2008.
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.
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 7539-8:2000 has been approved by CEN as a EN ISO 7539-8:2008 without any modification.

INTERNATIONAL ISO
STANDARD 7539-8
First edition
2000-07-01
Corrosion of metals and alloys — Stress
corrosion testing —
Part 8:
Preparation and use of specimens to
evaluate weldments
Corrosion des métaux et alliages — Essais de corrosion sous contrainte —
Partie 8: Préparation et utilisation des éprouvettes pour évaluer les
assemblages soudés
Reference number
ISO 7539-8:2000(E)
©
ISO 2000
ISO 7539-8:2000(E)
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ii © ISO 2000 – All rights reserved

ISO 7539-8:2000(E)
Contents Page
Foreword.iv
1 Scope .1
2 Normative references .1
3 Terms and definitions .2
4 Special considerations for weldments .3
5 Specimen types.4
6 Preparation of weldments and test specimens .8
7 Testing Procedures .10
8 Assessment.11
9 Test report .11
Annex A (informative) Terms and definitions which have not been internationally agreed .13
Bibliography.18
ISO 7539-8:2000(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 3.
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 part of ISO 7539 may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 7539-8 was prepared by Technical Committee ISO/TC 156, Corrosion of metals and
alloys.
ISO 7539 consists of the following parts, under the general title Corrosion of metals and alloys — Stress corrosion
testing:
� Part 1: General guidance on testing procedures
� Part 2: Preparation and use of bent-beam specimens
� Part 3: Preparation and use of U-bend specimens
� Part 4: Preparation and use of uniaxially loaded tension specimens
� Part 5: Preparation and use of C-ring specimens
� Part 6: Preparation and use of pre-cracked specimens
� Part 7: Slow strain rate testing
� Part 8: Preparation and use of specimens to evaluate weldments
� Part 9: Preparation and use of pre-cracked specimens for tests under rising load or rising displacement
Annex A of this part of ISO 7539 is for information only.
iv © ISO 2000 – All rights reserved

INTERNATIONAL STANDARD ISO 7539-8:2000(E)
Corrosion of metals and alloys — Stress corrosion testing —
Part 8:
Preparation and use of specimens to evaluate weldments
1 Scope
This part of ISO 7539 covers the procedures available for stress corrosion testing of welded specimens and
examines the additional factors which must be taken into account when conducting tests on welded specimens. In
particular this part of ISO 7539 gives recommendations for the choice of specimens and test procedures to
determine the resistance of a metal to stress corrosion when it is welded.
The term “metal”, as used in this part of ISO 7539, includes alloys.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this part of ISO 7539. For dated references, subsequent amendments to, or revisions of, any of these publications
do not apply. However, parties to agreements based on this part of ISO 7539 are encouraged to investigate the
possibility of applying the most recent editions of the normative documents indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain
registers of currently valid International Standards.
ISO 857-1:1998, Welding and allied processes — Vocabulary — Part 1: Metal welding processes.
ISO 7539-2:1989, Corrosion of metals and alloys — Stress corrosion testing — Part 2: Preparation and use of
bent-beam specimens.
ISO 7539-3:1989, Corrosion of metals and alloys — Stress corrosion testing — Part 3: Preparation and use of
U-bend specimens.
ISO 7539-4:1989, Corrosion of metals and alloys — Stress corrosion testing — Part 4: Preparation and use of
uniaxially loaded tension specimens.
ISO 7539-5:1989, Corrosion of metals and alloys — Stress corrosion testing — Part 5: Preparation and use of
C-ring specimens.
1)
ISO 7539-6:— , Corrosion of metals and alloys — Stress corrosion testing — Part 6: Preparation and use of pre-
cracked specimens.
ISO 7539-7:1989, Corrosion of metals and alloys — Stress corrosion testing — Part 7: Slow strain rate testing.
IEC 60050-851 (1991-08), International Electrotechnical Vocabulary — Chapter 851: Electric Welding.
1) To be published. (Revision of ISO 7539-6:1989)
ISO 7539-8:2000(E)
3 Terms and definitions
For the purposes of this part of ISO 7539 the following terms and definitions apply.
3.1
welding
operation which unites materials by means of heat or pressure, or both, in such a way that there is continuity in the
nature of the materials which have been joined and in which filler metal, the melting temperature of which is of the
same order as that of the parent metal(s), may or may not be used
NOTE This definition also includes surfacing.
[ISO 857-1]
3.1.1
fusion welding
welding involving localized melting without the application of force and with or without the addition of filler metal
[ISO 857-1]
3.1.2
arc welding
fusion welding in which heat for welding is obtained from an electric arc or arcs
[ISO 857-1; IEC 60050-851]
3.1.3
diffusion welding
pressure welding in which the workpieces are kept in contact under a specified continual pressure and are heated,
either on their faying surfaces or in their entirety, at a defined temperature for a controlled time
NOTE 1 This process results in local plastic deformation and also, owing to the very close contact between the surfaces, the
diffusion of the atoms through the interface. The end result is thus complete continuity of the material.
NOTE 2 The operation may take place in a vacuum, under a gas shield or in a fluid, preferably without the addition of a filler
metal.
SeeFigure1.
[ISO 857-1]
2 © ISO 2000 – All rights reserved

ISO 7539-8:2000(E)
Key
1 Induction heating element
2 Work chamber
3Workpiece
4Weld
Figure 1 — Diffusion welding
3.2
arc voltage
voltage across the arc, including the anode and cathode voltage drop, measured as near as possible to the arc
[IEC 60050-851]
See annex A.
4 Special considerations for weldments
4.1 General
The factors given in this clause may all influence the corrosion and/or mechanical properties of a weldment relative
to that of the parent metal and their effects may require consideration in stress corrosion test procedures. Whilst
the considerations listed below are relevant to the more common fusion welding processes, similar consideration
shall also be given to solid phase (non-fusion) welding processes and diffusion welding.
Weld regions are more likely than the parent metal to contain defects which may influence corrosion and stress
corrosion behaviour, e.g. microcracking, lack of fusion and porosity. For this reason, examination of the weld shall
be undertaken to assess whether the failure of any specimen is the result of pre-existing defects rather than stress
corrosion.
It is recommended that the weldment be characterized with regard to residual welding stresses, surface condition
and weld defects prior to testing. See clause 7.
4.2 Changes in microstructure
In fusion welding, the application of heat to a parent metal produces microstructural changes in the heat affected
zone (HAZ) of the parent metal adjacent to the weld junction. A rapidly-cooled weld metal differs microstructurally
ISO 7539-8:2000(E)
and chemically from the parent metal and is more typical of a cast structure. These differences may influence both
weldment corrosion and mechanical properties, as well as susceptibility to stress corrosion cracking.
Some alloys such as C-Mn steels display a visible HAZ. However, in some alloys, welding may also produce
precipitation and segregation effects within the parent metal remote from the visible HAZ.
4.3 Non-metallic inclusions
In addition to changes in chemical composition, the welding procedure and conditions used may result in a weld
metal with a non-metallic inclusion content and distribution different from that of the parent metal. This may
influence weldment corrosion and stress corrosion cracking behaviour.
4.4 Stress concentration effects
Shrinkage stresses following welding will introduce residual welding stresses which will be both transverse and
longitudinal with respect to the welding direction (and through thickness in thick-walled samples). Tensile stresses
are usually generated at the weld, with balancing compressive stresses in the parent metal. In addition, weld
geometry may cause further stress concentration effects.
5 Specimen types
5.1 General
The design and type of specimen used depend on the form of the metal from which the specimen is to be made
and on the objective of the test.
The test specimens described in ISO 7539 parts 2-7 are suitable for tests on weldments, subject to the additional
considerations presented in this part of ISO 7539. In addition, a number of other types of specimens, as described
in 5.2.1 to 5.2.8 below, can be used.
Specimens can be prepared from weldments in the as-welded or post-weld heat-treated conditions. It is
recommended that specimens be tested in the same condition of heat treatment as that of the intended application.
5.2 Types of specimen
5.2.1 Flat weldment
SeeFigure2.
This type of weldment is applicable for all tension and bend specimens and for any welding procedure whether
involving single- or multi-pass welds. The weldment may also be used to evaluate the effect of residual welding
stresses.
5.2.2 Circular bead weldment
SeeFigure3.
The welding procedure involves one circular bead deposit of weld metal. The circular weld develops residual
welding stresses. It is applicable to any material form that can be machined to the recommended size as specified
in Figure 3.
4 © ISO 2000 – All rights reserved

ISO 7539-8:2000(E)
5.2.3 Bead-on-bar weldment
SeeFigure4.
The longitudinal fusion welds at diametrically opposite positions on the bar develop residual welding stresses in the
bar. Hence, this weldment can be used to evaluate the tendency for stress corrosion cracking of the parent metal. It
is applicable to materials that can be machined to approximately 25 mm diameter.
5.2.4 Direct tension specimen
SeeFigure5.
This specimen type is stressed in uniaxially loaded tension (see ISO 7539-4 and ISO 7539-7). Notches, with or
without pre-cracks, may be introduced into the weld metal, parent metal or heat affected zone (see ISO 7539-6).
These specimens also may be made exclusively from weld metal.
5.2.5 U-bend specimen
SeeFigure6.
The U-bend specimen is applicable to any weldment that can be formed into a U-shape without mechanical
cracking or localized bending in the heat affected zone (see ISO 7539-3). The bending operation after welding
creates high levels of elastic and plastic strain resulting in a wide range of stresses in a single specimen. The
presence of residual welding stresses makes this a particularly severe test procedure.
5.2.6 Bent-beam specimens
SeeFigure7.
These specimens are machined from welded plate into rectangular bar with the welding direction normal to or
parallel to the axis of the specimen (see ISO 7539-2). They can be loaded in 3-point or 4-point bending to measure
the stress corrosion tendencies in the weld region.
5.2.7 Pre-cracked specimens
SeeFigure8.
Pre-cracked specimens can be used to measure the tendency for stress corrosion cracking (see ISO 7539-6) in
various parts of the weldment. Caution should be exercise
...