SIST EN ISO 7539-5:1999

Corrosion of metals and alloys - Stress corrosion testing - Part 5: Preparation and use of C-ring specimens (ISO 7539-5:1989)

Covers procedures for designing, preparing, stressing, exposing and inspecting C-ring specimens. These versatile, economical specimens may be used to test a variety of product forms including parts joined by welding. C-ring specimens may be stressed to predeterminded levels, using simple equipment for application of either constant load or constant strain.

Korrosion der Metalle und Legierungen - Prüfung der Spannungsrißkorrosion - Teil 5: Vorbereitung und Anwendung von C-Ring-Proben (ISO 7539-5:1989)

Der vorliegende Teil von ISO 7539 behandelt Verfahren für die Gestaltung, Vorbereitung, Belastung, Auslagerung und Kontrolle von C-Ring-Proben zur Untersuchung der Anfälligkeit von Metallen für Spannungsrißkorrosion. Eine Analyse der Spannungsart und -verteilung in der C-Ring-Probe wird vorgestellt. In diesem Teil von ISO 7539 werden mit der Benennung "Metall" auch Legierungen erfaßt.

Corrosion des métaux et alliages - Essais de corrosion sous contrainte - Partie 5: Préparation et utilisation des éprouvettes en forme d'anneau en C (ISO 7539-5:1989)

1.1 La présente partie de l'ISO 7539 couvre les procédures de définition, de préparation, de mise sous contrainte, d'exposition et d'examen d'éprouvettes en forme d'anneau en C, servant à évaluer la sensibilité d'un métal à la corrosion sous contrainte. Elle présente une analyse de l'état et de la distribution de la contrainte dans l'anneau en C. Pour les besoins de la présente partie de l'ISO 7539, le terme « métal » inclut également les alliages. 1.2 L'anneau en C constitue une éprouvette économique et polyvalente pour déterminer la sensibilité à la corrosion fissurante sous contrainte de tous les types de métaux entrant dans la composition d'une multitude de formes de produits. Il est particulièrement bien adapté aux essais de tubes, barres et tôles (voir figure 1). Des éprouvettes entaillées peuvent également être utilisées (voir 5.3.8). 1.3 Les éprouvettes en anneau en C peuvent être mises sous contrainte à des niveaux prédéterminés par un équipement simple appliquant une charge ou une déformation croissante.

Korozija kovin in zlitin - Ugotavljanje pokanja zaradi napetostne korozije - 5. del: Priprava in uporaba preskušancev v obliki C-obročev (ISO 7539-5:1989)

General Information

• Status: Published
• Publication Date: 30-Sep-1999
• ICS: 77.060 - Corrosion of metals
• Technical Committee: IPKZ - Protection of metals against corrosion
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Oct-1999
• Due Date: 01-Oct-1999
• Completion Date: 01-Oct-1999
• Ref Project: EN ISO 7539-5:1995 - Corrosion of metals and alloys - Stress corrosion testing - Part 5: Preparation and use of C-ring specimens (ISO 7539-5:1989)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 7539-5:1999
01-oktober-1999
.RUR]LMDNRYLQLQ]OLWLQ8JRWDYOMDQMHSRNDQMD]DUDGLQDSHWRVWQHNRUR]LMHGHO
3ULSUDYDLQXSRUDEDSUHVNXãDQFHYYREOLNL&REURþHY,62
Corrosion of metals and alloys - Stress corrosion testing - Part 5: Preparation and use of
C-ring specimens (ISO 7539-5:1989)
Korrosion der Metalle und Legierungen - Prüfung der Spannungsrißkorrosion - Teil 5:
Vorbereitung und Anwendung von C-Ring-Proben (ISO 7539-5:1989)
Corrosion des métaux et alliages - Essais de corrosion sous contrainte - Partie 5:
Préparation et utilisation des éprouvettes en forme d'anneau en C (ISO 7539-5:1989)
Ta slovenski standard je istoveten z: EN ISO 7539-5:1995
ICS:
77.060 Korozija kovin Corrosion of metals
SIST EN ISO 7539-5:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 7539-5:1999

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SIST EN ISO 7539-5:1999

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SIST EN ISO 7539-5:1999

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SIST EN ISO 7539-5:1999
INTERNATIONAL
ISO
STANDARD
7539-5
First edition
1989-12-15
Corrosion of metals and alloys - Stress
corrosion testing -
Part 5:
Preparation and use of C-ring specimens
Corrosion des mhtaux et alfiages - Essais de corrosion sous contrainte -
Partie 5: Prhparation et utilisation des hprouvettes en forme d’anneau en C
Reference number
ISO 7539-5 : 1989 (El

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SIST EN ISO 7539-5:1999
ISO 7539-5 : 1989 (El
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. Esch 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, govern-
mental 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.
Draft International Standards adopted by the technical committees are circulated to
the member bodies for approval before their acceptance as International Standards by
the ISO Council. They are approved in accordance with ISO procedures requiring at
least 75 % approval by the member bodies voting.
International Standard ISO 7539-5 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 altoys - S tress corrosion tes ting :
-
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 uniaxialy 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 welded specimens
Annex A forms an integral part of this part of ISO 7539.
0 ISO 1989
All rights reserved. No patt of this publication may be reproduced or utilized in any form or by any
means, electronie or mechanical, including photocopying and microfiim, without Permission in
writing from the publisher.
International Organization for Standardization
Case postale 56 l CH-121 1 Geneve 20 l Switzerland
Printed in Switzerland

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SIST EN ISO 7539-5:1999
ISO 7539-5 : 1989 (EI
Introduction
This part of ISO 7539 is one of a series giving procedures for designing, preparing and
using various forms of test specimen to carry out tests to establish a metals resistance
to stress corrosion.
Esch of the Standards in the series needs to be read in association with ISO 7539-1.
This helps in the choice of an appropriate test procedure to suit particular
circumstances as well as giving guidance towards assessing the significance of the
results of the tests.

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SIST EN ISO 7539-5:1999
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SIST EN ISO 7539-5:1999
INTERNATIONAL STANDARD ISO 7539-5 : 1989 (E)
Corrosion of metals and alloys - Stress corrosion
testing -
Part 5:
Preparation and use of C-ring specimens
3 Definitions
1 Scope
For the purposes of this part of ISO 7539, the definitions given
1.1 This part of ISO 7539 covers procedures for designing,
in ISO 7539-1 are applicable.
exposing and inspecting C-ring test
preparing, stressing,
specimens for investigating the susceptibility of a metal to
stress corrosion. Analysis of the state and distribution of stress
in the C-ring is presented.
4 Principle
The term “metal” as used in this part of ISO 7539 includes
4.1 The test consists of subjecting a specimen to constant
alloys.
load or to constant strain with a view to determining stress cor-
rosion susceptibility by reference to one or more of the
1.2 The C-ring is a versatile, economical specimen for deter-
/
Parameters enumerated in clause 7.
mining the susceptibility to stress corrosion cracking of all
types of metals in a wide variety of product forms including
Parts joined by welding. lt is particularly suitable for tests of
4.2 Corrosive environments may Cause a deterioration of the
tube, rod and plate (sec figure 1). Notched specimens may also
proper-Ges of stressed materials beyond those observed with
be used (sec 5.3.8).
the same combination of environment and material when the
latter is not subjected to stress. This enhanced deterioration
1.3 C-ring specimens may be stressed to predetermined
may be expressed in a number of different ways for the purpose
levels, using simple equipment for application of either con-
of assessing stress corrosion susceptibility.
stant load or constant strain.
4.3 The commonest form of deterioration due to stress cor-
2 Normative references
rosion involves the initiation and growth of Cracks, one or more
of which may eventually lead to total failure of a specimen if the
The following Standards contain provisions which, through
test is conducted for an appropriate time.
reference in this text, constitute provisions of this part of
ISO 7539. At the time of publication, the editions indicated
were valid. All Standards are subject to revision, and Parties to 4.4 Wide variations in test results may be obtained for a
given metal and environment even when testing nominally
agreements based on this part of ISO 7539 are encouraged to
investigate the possibility of applying the most recent editions identical specimens and the replication of tests is frequently
necessary. If specimens are prepared to different sizes or orien-
of the Standards indicated below. Members of IEC and ISO
tations or are subjected to different stressing procedures, test
maintain registers of currently valid International Standards.
results may be even more variable.
ISO 7539-1 : 1987, Corrosion of metals and alle ys - Stress
corrosion testing - Part 1: General guidance on testing pro-
4.5 The time required for Cracks to appear after exposure of
cedures.
stressed specimens to the test environment or the threshold
stress below which Cracks do not appear tan be used as a
ISO 7539-6 : 1989, Corrosion of metals and alloys - Stress
corrosion testing - Part 6: Preparation and use of pre-cracked measure of the stress corrosion resistance of the material in the
test environment at the stress level employed.
specimens.
1

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SIST EN ISO 7539-5:1999
ISO 7539-5 : 1989 (E)
Rod and bar
Long
Figure 1 - Sampling procedure for testing various products

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SIST EN ISO 7539-5:1999
ISO 7539-5 : 1989 (El
varies across the width of the ring to an extent which depends
5 Spetimens
on the width-to-thickness and diameter-to-thickness ratios. In
general, if loaded as shown in figure 3a) and b), the tensile
5.1 Specimen design
stress on the outer surface is greater at the edges than at the
centre, while if loaded as shown in figure 3~1, the tensile stress
5.1 .l The size of C-rings may be varied over a wide range, but
on the inner surface is less at the edges than at the centre.
C-rings with an outside diameter less than 15 mm are not
recommended because of increased diff iculties in machining
5.2.2 Another characteristic of the stress System in the
and decreased precision in stressing. The dimensions of the
ring tan affect the stress state, and these considerations are C-rings is the presence of biaxial Stresses; that is, transverse as
well as circumferential Stresses are developed. The transverse
discussed in 5.2. Figure 2 is a drawing showing typical dimen-
sions for the manufacture of a C-ring. axial stress varies from a maximum at the mid-width to zero at
the edges, and has the same sign as the circumferential stress.
In general, the transverse stress decreases with decreasing
5.1.2 In testing thick sections that have a directional grain
width-to-thickness and increasing diameter-to-thickness ratios.
structure, it is essential that the C-ring should be orientated in
the section so that the direction of the principal stress is normal
to the plane of minimum resistance to stress corrosion crack- 5.2.3 In the case of the notched C-ring a triaxial stress state is
present adjacent to the root of the notch. In addition, the cir-
ing. If the ring is not so orientated it will tend to Crack off-centre
at a location where the stress is unknown and lower than the cumferential stress at the root of the notch will be greater than
the nominal stress and generally may be expected to be in the
calculated stress (sec 5.3.3). Appropriate instructions should
therefore be given to Workshop personnel. C-ring specimens plastic range.
may be used as notched or fatigue pre-cracked specimens, the
stress states of which are considered in 5.3.8 for notched
5.2.4 When C-rings are machined from products that contain
specimens and in ISO 7539-6 for pre-cracked specimens.
appreciable residual stress or are subjected to heat treatment
involving quenching after being machined, internal Stresses
may be present. These may introduce errors in the calculated
5.2 Stress considerations
stress.
5.2.1 The stress of principal interest in the C-ring specimen is
lt is necessary to measure the tubing diameter before and after
the circumferential stress. This is not uniform: there is a
the axial tut is made and to use these measurements to calcu-
gradient through the thickness, varying from a maximum in
late the residual Stresses in the tube.
tension on one surface to a maximum in compression on the
opposite surface. The stress varies also around the cir-
The possibility of relaxation during the exposure period
5.2.5
cumference of the C-ring from zero at each bolt hole to a maxi-
should be considered, especially when specimens are exposed
mum at the centre of the arc opposite the stressing bolt. The
at elevated temperatures. Relaxation tan be estimated if creep
stress calculated according to annex A is present only along a
data are available for both the ring and the stressing bolt.,
line across the ring at the middle of the arc. Thus, if the stress is
determined by measuring the strain on the tension surface sf
NOTE - If the ring and bolt have different coefficients of thermal
the C-ring, the strain gauge should be positioned at the middle expansion, the applied stress may be significantly changed when
of the arc in Order to indicate the maximum strain. The stress testing at elevated temperatures. Also, if plastic insulators are used to
Dimensions in millimetres
@ext t0,05
19 min. 20,4
Example of C-ring specimen
Figure 2 -
3

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SIST EN ISO 7539-5:1999
ISO 7539-5 : 1989 EI
avoid galvanic corrosion, the possibility of stress relaxation should be
anticipated.
E is the modulus of elasticity, in newtons Square
Per
5.3 Stressing methods metre;
5.3.1 C-ring specimens are usually loaded under constant is Poisson’s ratio;
P
displacement conditions with tensile stress produced on the
exterior of the ring by tightening a bolt centred on the diameter
is the circumferential strain;
%
of the ring [sec figure 3a)l.
is the transverse strain.
%
5.3.2 C-rings tan alternatively be stressed in the reverse dir
...