SIST EN ISO 11463:2008
(Main)Corrosion of metals and alloys - Evaluation of pitting corrosion (ISO 11463:1995)
Corrosion of metals and alloys - Evaluation of pitting corrosion (ISO 11463:1995)
Gives guidance on the selection of procedures that can be used in the identification and examination of pits and in the evaluation of pitting corrosion.
Korrosion von Metallen und Legierungen - Bewertung der Lochkorrosion (ISO 11463:1995)
Diese Internationale Norm bietet Hinweise zur Auswahl von Verfahren, die zum Nachweis und Untersuchen von Löchern und zur Bewertung der Lochkorrosion angewendet werden können.
Corrosion des métaux et alliages - Évaluation de la corrosion par piqures (ISO 11463:1995)
La présente Norme internationale constitue un guide destiné à aider à choisir des méthodes pouvant être utilisées dans l'identification et l'examen des piqûres et dans l'évaluation de la corrosion par piqûres.
Korozija kovin in zlitin - Vrednotenje jamičaste korozije (ISO 11463:1995)
General Information
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Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 11463:2008
01-julij-2008
.RUR]LMDNRYLQLQ]OLWLQ9UHGQRWHQMHMDPLþDVWHNRUR]LMH ,62
Corrosion of metals and alloys - Evaluation of pitting corrosion (ISO 11463:1995)
Corrosion des métaux et alliages - Évaluation de la corrosion par piqures (ISO
11463:1995)
Ta slovenski standard je istoveten z: EN ISO 11463:2008
ICS:
77.060 Korozija kovin Corrosion of metals
SIST EN ISO 11463:2008 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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EUROPEAN STANDARD
EN ISO 11463
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2008
ICS 77.060
English Version
Corrosion of metals and alloys - Evaluation of pitting corrosion
(ISO 11463:1995)
Corrosion des métaux et alliages - Évaluation de la Korrosion von Metallen und Legierungen - Bewertung der
corrosion par piqûres (ISO 11463:1995) Lochkorrosion (ISO 11463:1995)
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.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
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 11463:2008: E
worldwide for CEN national Members.
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EN ISO 11463:2008 (E)
Contents Page
Foreword.3
2
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EN ISO 11463:2008 (E)
Foreword
The text of ISO 11463:1995 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
11463:2008 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 11463:1995 has been approved by CEN as a EN ISO 11463:2008 without any modification.
3
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INTERNATIONAL ISO
STANDARD 11463
First edition
1995-12-15
Corrosion of metals and alloys - Evaluation
of pitting corrosion
Corrosion des mk taux et alliages - Evaluation de Ia corrosion par piqfires
Reference number
ISO 11463:1995(E)
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ISO 11463:1995(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. 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, 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.
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.
International Standard ISO 11463 was prepared by Technical Committee
ISO/TC 156, Corrosion of metals and alloys.
Annexes A and B of this International Standard are for information only.
0 ISO 1995
All rights reserved. Unless otherwise specified, no part of this publication may be
reproduced or utilized in any form or by any means, electronie or mechanical, including
photocopying and microfilm, without Permission in writing from the publisher.
International Organization for Standardi zation
Case Postale 56 l CH-121 IG eneve 20 l Switzerland
Printed in Switzerland
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ISO 11463:1995(E)
@ ISO
Introduction
lt is important to be able to determine the extent of pitting, either in a
Service application where it is necessary to estimate the remaining life in a
metal structure, or in laboratory test Programmes that are used to select
pitting-resistant materials for a particular Service (see [l] in annex B).
The application of the materials to be tested will determine the minimum
pit size to be evaluated and whether total area covered, average pit depth,
maximum pit depth or another criterion is the most important to measure.
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INTERNATIONAL STANDARD o Iso
ISO 11463:1995(E)
Corrosion of metals and alloys - Evaluation of pitting
corrosion
removal of particulate corrosion products should be
1 Scope
followed and reserved for future identification.
This International Standard gives guidance on the
3.12 To expose the pits fully, it is recommended
selection of procedures that tan be used in the
that cleaning procedures should be used to remove
identification and examination of pits and in the
the corrosion products and avoid solutions that attack
evaluation of pitting corrosion.
the base metal excessively (see ISO 8407). lt may be
advisable during cleaning to probe the pits with a
pointed tool to determine the extent of undercutting
2 Normative reference or subsurface corrosion (see figure 1). However,
scrubbing with a stiff-bristle brush will often enlarge
the pit openings sufficiently by removal of corrosion
The following Standard contains provisions which,
products or undercut metal to make the pits easier to
through reference in this text, constitute provisions of
evaluate.
this International Standard. At the time of publication,
the edition indicated was valid. All Standards are sub-
3.1.3 Examine the cleaned metal surface to deter-
ject to revision, and Parties to agreements based on
mine the approximate size and distribution of pits.
this International Standard are encouraged to investi-
Follow this procedure by a more detailed examination
gate the possibility of applying the most recent edition
through a microscope using low magnification
of the Standard indicated below. Members of IEC and
(approximately X 20).
ISO maintain registers of currently valid International
Standards.
3.1.4 Determine the size, shape and density of pits.
ISO 8407:1991, Corrosion of metals and alloys -
3.1.4.1 Pits may have various sizes and shapes. A
Removal of corrosion products from corrosion test
visual examination of the metal surface may show a
specimens.
round, elongated or irregular opening, but it seldom
provides an accurate indication of corrosion beneath
the surface. Thus it is often necessary to cross-sec-
3 Identification and examination of pits
tion the pit to see its actual shape and to determine its
true depth. Several variations in the Cross-sectioned
shape of pits are shown in figure 1.
3.1 Visual inspection
3.1.4.2 lt is difficult to determine pit density by
A visual examination of the corroded metal surface
counting pits through a microscope eyepiece, but the
with or without the use of a Iow-power magnifying
task may be made easier by the use of a plastic grid.
glass may be used to determine the extent of cor-
Place the grid, containing 3 mm to 6 mm squares, on
rosion and the apparent location of pits. lt is often
the metal surface. Count and record the number of
advisable to Photograph the corroded surface so that
pits in each Square, and move across the grid in a sys-
it tan be compared with the clean surface after the
tematic manner until all the surface has been covered.
removal of corrosion products.
This approach minimizes eye-strain because the eyes
3.1.1 If the metal specimen has been exposed to an tan be taken from the field of view without fear of
unknown environment, the composition of the cor- losing the area of interest. Enlarged Photographs of
rosion products may be of value in determining the the area of interest may also be used to reduce eye-
Cause of corrosion. Recommended procedures in the strain.
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@ ISO
ISO 11463:1995(E)
a) Narrow, deep
b) Elliptical c) Wide, shallow
/
T
v
T
d) Subsurface
e) Undercutting
(Horizontal)
(Vertical)
f) Microstructural orientation
Figure 1 - Variations in the Cross-sectional shape of pits
3.1.5 To carry out a metallographic examination sel- metal thickness to be detected. This technique has
ect and tut out a representative Portion of the metal only slight application to pitting detection, but it might
surface containing the pits and prepare a metal- be useful for comparing specimens before and after
lographic specimen in accordance with recommended corrosion to determine whether pitting has occurred
procedures. If corrosion products are to be examined and whether it is associated with previous porosity. lt
in Cross-section, it may be necessary to fix the surface may also be useful to determine the extent of subsur-
in a mounting compound before cutting. Examine face and undercutting pitting (see figure 1).
microscopically to determine whether there is a
relation between pits and inclusions or microstructure,
3.2.2 Electromagnetit
or whether the cavities are true pits or might have re-
sulted from metal loss caused by intergranular cor-
3.2.2.1 Eddy currents may be used to detect defects
rosion, dealloying, etc.
or irregularities in the structure of electrically conduc-
tive materials. When a specimen is exposed to a
varying magnetic field, produced by connecting an
3.2 Non-destructive inspection
alternating current to a coil, eddy currents are induced
in the specimen and they in turn produce a magnetic
A number of techniques has been developed to assist
field of their own. Materials with defects will produce
in the detection of Cracks or cavities in a metal surface
a magnetic field that is different from that of a refer-
without destroying the material. See [l] in annex B.
ence material without defects, and an appropriate de-
These methods are less effective for locating and de-
tection instrument is required to determine these dif-
fining the shape of pits than some of those previously
ferences.
described, but they merit consideration because they
are often used in situ, and thus are more applicable to
3.2.2.2 The induction of a magnetic field in ferro-
field applications.
magnetic materials is another approach that is used.
Discontinuities that are transverse to the direction of
3.2.1 Radiographit the magnetic field Cause a leakage field to form above
the surface of the part. Ferromagnetic particles are
Radiation, such as X-rays, Passes through the Object. placed on the surface to detect the leakage field and
The intensity of the emergent rays varies with the to outline the size and shape of the discontinuities.
thickness of the material. Imperfections may be de- Rather small imperfections tan be detected by this
tected if they Cause a Change in the absorption of X- method. However, the method is limited by the re-
rays. Detectors or films are used to provide an image quired directionality of defects to the magnetic field,
of interior imperfections. The metal thickness that tan by the possible need for demagnetization of the ma-
be inspected is dependent on the available energy
terial and by the limited shape of Parts that tan be
output. Pores or pits must be as large as 0,5 % of the
examined.
2
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@ ISO ISO 11463:1995(E)
3.2.3 Sonics 4.2 Pit depth measurement
In the use of ultrasonics, pulses of Sound energy are
4.2.1 Metallography
transmitted through a couplant, such as oil or water,
on to the metal surface where waves are generated.
Pit depth may be determined by sectioning vertically
The reflected echoes are converted to electrical sig-
through a preselected pit, mounting the cross-sec-
nals that tan be interpreted to show the location of
tioned pit metallographically and polishing the surface.
flaws or pits. Both contact and immersion methods
A better or alternative way is to section slightly away
are used. The test shall be carried out from the non-
from the pit and slowly grind until the pit is in the
pitted face. The test has good sensitivity, although it is
Cross-section. Sectioning through a pit tan be difficult
unlikely to detect pits of less than 1 mm diameter or
and one may miss the deepest Portion. The depth of
within 1 mm of a non-pitted face, and provides instan-
the pit is measured on the flat, polished surface by the
taneous information about the size and location of
use of a microscope with a calibrated eyepiece. The
flaws. However, reference Standards are required for
method is very accurate, but it requires good Operator
comparison and training is needed to interpret the re-
skill and good judment in the selection of the pit and
sults properly.
good technique in cutting through the pit. Its
limitations are that it is time-consuming, the deepest
pit may not have been selected and the pit may not
3.2.4 Penetrants
have been sectioned at the deepest Point of
Defects opening to the surface tan be detected by
Penetration. The method, however, is the only suit-
the application of a penetrating liquid that sub-
able for the evaluation of the pit shape as in figure 1.
sequently exudes from the surface after the excess
penetrant has been removed. Defects are located by
4.2.2 Machining
spraying the surface with a developer that reacts with
a dye in the penetrant, or the penetrant may contain a
See [Zl and [3] in annex B.
fluorescent material that is viewed under ultra-violet
light. The size of the defect is shown by the intensity
4.2.2.1 This method requires a Sample that is fairly
of the colour and the rate of bleed-out. This technique
regular in shape, and it usually involves the destruc-
provides only an approximation of the depth and size
tion of the specimen. Measure the thickness of the
of pits.
specimen between two areas that have not been af-
fected by general corrosion. Select a Portion of the
3.2.5 Replication
surface on one side of the specimen that is relatively
unaffected; then machine the opposite surface where
Images of a pitted surface tan be created by applying
the pits are located on a precision lathe, grinder or mill
a material to the surface which conforms to the shape
until all signs of corrosion have disappeared. Some
of the pits and tan be removed without damaging its
difficulty from galling and smearing may be encoun-
shape. This method will not work however, for pits of
tered with soft metals and pits may be obliterated.
subsurface or undercut type. The removed material
Conversely, inclusions may be removed from the
contains a replica of the original surface which, in
metal thus confusing examination. Measure the thick-
some cases, is easier to analyze than the original.
ness of the specimen between the unaffected surface
Replication is particularly useful for analysis of very
and subtract from the original thickness to give the
small pits.
maximum depth of pitting. Repeat this procedure on
the unmachined surface unless the thickness has
been reduced by 50 % or more during the machining
of the first side.
4 Extent of pitting
4.2.2.2 Thi
...
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