prEN ISO 4969

SLOVENSKI STANDARD
01-oktober-2026
Jeklo - Metoda jedkanja za makroskopsko preiskavo (ISO 4969:2015)
Steel - Etching method for macroscopic examination (ISO 4969:2015)
Acier - Méthode d'attaque pour examen macroscopique (ISO 4969:2015)
Ta slovenski standard je istoveten z: prEN ISO 4969
ICS:
77.040.99 Druge metode za Other methods of testing of
preskušanje kovin metals
77.080.20 Jekla Steels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 4969
Second edition
2015-07-01
Steel — Etching method for
macroscopic examination
Acier — Méthode d’attaque pour examen macroscopique
Reference number
ISO 4969:2015(E)
©
ISO 2015
ISO 4969:2015(E)
© ISO 2015, Published in Switzerland
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ii © ISO 2015 – All rights reserved

ISO 4969:2015(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Principle . 1
3 Sampling . 1
4 Preparation . 2
5 Solutions . 2
6 Procedure. 3
7 Preservation of test pieces . 5
8 Test report . 6
Bibliography . 9
ISO 4969:2015(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
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electrotechnical standardization.
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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
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to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 17, Steel, Subcommittee SC 7, Methods of testing
(other than mechanical tests and chemical analysis).
This second edition cancels and replaces the first edition (ISO 4969:1980), which has been technically revised.
iv © ISO 2015 – All rights reserved

INTERNATIONAL STANDARD ISO 4969:2015(E)
Steel — Etching method for macroscopic examination
1 Scope
This International Standard establishes guidelines for the macroscopic examination of steel by hot
etching, room temperature etching and electrolytic etching.
The method has very wide application. Selection of the type, concentration and temperature of the
reagent, the etching apparatus and the conditions of surface preparation of the test piece make it
possible to achieve the required aim.
NOTE It might be difficult to see fine voids and cracks and discriminate between them and determine their
nature by macroetching.
2 Principle
2.1 The use of the test and the conditions for interpreting the results observed depend on the particular
case, details are presented in product standards or shall be subject to special agreement.
2.2 Macroscopic etching reveals the macrostructure of a metal test piece and any gross physical or
chemical irregularities present.
2.3 The reagent acts by dissolving different parts of the metal surface at unequal rates, and thus,
produces differences in level which makes observation possible.
2.4 Macroscopic examination after etching reveals lack of chemical uniformity (segregation of elements),
lack of physical uniformity (cracks, porosity), and any intentional or accidental structural variations such
as those caused, for instance, by hardening, decarburization or case hardening.
2.5 In addition, enhanced sensitivity can be achieved by altering the conditions of preparation and
attack. For instance, it is possible to reveal the dendritic structure of a metal or the presence of inclusions
or very small defects.
2.6 Observation of the etched surface is carried out with the unaided eye and/or with a magnifying
glass, or with a stereomicroscope.
3 Sampling
3.1 The position and number of sampling shall be determined according to the requirements of the
product standard, specification, contract or order. In the absence of any special requirements, sampling
must be planned according to the details of the manufacturing process and the grade being evaluated.
3.2 The macroetching test, as applied to the inspection of steel products of this method, is carried out
on slices, usually 13 mm to 25 mm in thickness. Disks or specimens are usually cut to reveal a transverse
surface, but the requirements of the specification, contract, or order can include the preparation and
examination of a longitudinal surface. In most cases, a longitudinally-oriented macroetching disc is taken
with the plane to be etched along the centre line of the wrought product and it includes both outside
surfaces with a length in the longitudinal direction, usually 1,5 times greater than the thickness or diameter.
ISO 4969:2015(E)
3.3 Samples may be cold cut from the source by any convenient fashion; saws and abrasive cut-off
wheels are particularly effective. The use of torch cutting or hot cutting should be used only when
necessary to cut a sample from a large piece. It is advisable to locate the test surfaces well, away from the
hot-cut surface avoiding sampling defects, such as deformations, heat affected zone, cracks, and so on.
3.4 Large cross sections can be cut into smaller pieces to facilitate handling and to comply with safety
requirements. The sectioning of the large specimens should be done so as not to disturb the central
portion of the section.
4 Preparation
4.1 The degree of surface preparation necessary depends on the precision required for macroscopic
examination by acid etching.
4.2 While rough machining, resulting in relatively coarse surfaces, can be sufficient in certain cases
(routine inspection to reveal shrinkage holes, for example), more careful machining is generally required.
4.3 The criteria to be observed when machining are as follows:
a) cutting-tool marking should not be pronounced, for example, as the result of incorrect adjustment,
excessively deep cuts or heavy feeds on the lathe or the shaping machine; good results are generally
obtained with a feed of approximately 0,1 mm;
b) there should be as little cold working of the surface as possible, due for instance
1) to a type of tool which is not suitable for the metal, or which is badly sharpened, and
2) to the use of unsuitable grinding wheels (less than 100 grit).
4.4 The main types of machining generally used are the following:
a) grinding, with or without preliminary machining;
b) shaping or turning, provided that the lathe is fitted with a speed adjuster.
4.5 Where acid etching is used to reveal very fine defects or structural irregularities (different welding
zones for instance), careful polishing is recommended; the finer the polishing, the better the definition. In
general, it is recommended that a machined surface finish with a Ra less than 30 μm be obtained.
4.6 After surface preparation, the sample is cleaned carefully with suitable solvents. Any grease, oil,
or other residue will produce uneven attack. Once cleaned, care s
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