ISO/TR 20580:2022

Preparation of metallographic specimens

This document presents a list of common practices in preparation methods of metallographic specimens for optical and scanning electron microscopy, including preliminary preparation, grinding and polishing of specimens as well as microstructure revelation methods covering the optical method, etching methods (chemical, electrolytic, constant potential, ion sputtering and high temperature relieving) and the interface layer method [1][2].

Confection des éprouvettes métallographiques

General Information

• Status: Published
• Publication Date: 30-Jun-2022
• ICS: 77.080.20 - Steels
• Technical Committee: ISO/TC 17/SC 7 - Methods of testing (other than mechanical tests and chemical analysis)
• Drafting Committee: ISO/TC 17/SC 7 - Methods of testing (other than mechanical tests and chemical analysis)
• Current Stage: 6060 - International Standard published
• Start Date: 01-Jul-2022
• Completion Date: 01-Jul-2022

Standards Content (Sample)

TECHNICAL ISO/TR
REPORT 20580
First edition
2022-07
Preparation of metallographic
specimens
Confection des éprouvettes métallographiques
Reference number
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Preliminary preparation . 1
4.1 Selection of metallographic specimens . 1
4.1.1 General . 1
4.1.2 General studies or routine work . 1
4.1.3 Study of failures . 1
4.2 Selection of type of section to be examined . 2
4.3 Size of metallographic specimens . 3
4.4 Cutting of metallographic specimens. 3
4.5 Marking of metallographic specimens . 3
4.6 Cleaning . 3
4.7 Mounting . 3
4.7.1 General . 3
4.7.2 Mechanical mounting . 4
4.7.3 Plastic mounting: . 4
5 Grinding. 5
5.1 Planar or rough grinding . 5
5.2 Fine grinding . 5
5.2.1 General . 5
5.2.2 Manual methods . 5
5.2.3 Automated methods . 6
6 Polishing . 6
6.1 General . 6
6.2 Mechanical polishing . 6
6.2.1 Rough polishing . 6
6.2.2 Fine polishing . 6
6.3 Electrolytic polishing . 6
6.4 Chemical polishing . 7
6.5 Vibratory polishing . 7
7 Microstructure revelation . 7
7.1 General . 7
7.2 Optical method . 7
7.3 Etching method . 7
[13]
7.3.1 Chemical etching . 7
[21]
7.3.2 Electrolytic etching . 7
7.3.3 Constant potential etching . 8
7.3.4 Ion sputtering etching (cathode vacuum etching) . 8
7.3.5 High temperature relieving etching. 8
7.4 Interference layer method . . 8
Annex A (informative) Etchants for metals . 9
Bibliography .16
iii
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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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
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
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 7, Methods of
testing (other than mechanical tests and chemical analysis).
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
TECHNICAL REPORT ISO/TR 20580:2022(E)
Preparation of metallographic specimens
1 Scope
This document presents a list of common practices in preparation methods of metallographic
specimens for optical and scanning electron microscopy, including preliminary preparation, grinding
and polishing of specimens as well as microstructure revelation methods covering the optical method,
etching methods (chemical, electrolytic, constant potential, ion sputtering and high temperature
[1][2]
relieving) and the interface layer method .
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Preliminary preparation
4.1 Selection of metallographic specimens
4.1.1 General
Because the metallographic examination serves a specified purpose that differs from case to case,
there is no one single way to select and prepare specimens. However, it is the accepted state of the art
to select specimens that are representative of the material that is being studied. The location, type of
section and number of the specimens to be studied are usually dictated by the manufacture method of
metals, examination intent or purpose, related standards or agreement upon enquiry.
4.1.2 General studies or routine work
Specimens are generally chosen from locations most likely to reveal the maximum variations within
[3]
the material under study . For example, specimens could be taken from a casting in the zones
wherein maximum segregation might be expected to occur as well as specimens from sections where
[4]
segregation could be at a minimum ; in the examination of strip or wire, test specimens are often
[5]
taken from each end of the coils ; heat or surface treated specimens are often taken so as to include
[6]
all the heat or surface treated layers ; welding specimens often incorporate the welding seam, heat
[7]
affected zone and base metal .
4.1.3 Study of failures
In nearly all situations, test specimens are taken as closely as possible to the fracture or to the initiation
of the failure. Before taking the metallographic specimens, study of the fracture surface is completed,
[8]
or at the very least, the fracture surface is documented . In many cases, specimens are taken from a
sound area for a comparison of structures and properties.
4.2 Selection of type of section to be examined
4.2.1 Having established the location of the metallographic samples, the type of section to be
examined is decided. The locations of surfaces examined are always given in reporting results an
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