ISO 5490

Steel — Rating and classifying nonmetallic inclusions using the scanning electron microscope

This test method covers procedures to obtain particle size distribution, chemical classification, and ratings of nonmetallic inclusions in steels using an scan¬ning electron microscope (SEM) with X-ray analysis and automatic image analysis capabilities

Acier — Classement et classification des inclusions non métalliques à l'aide du microscope électronique à balayage

General Information

• Status: Not Published
• 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: 6000 - International Standard under publication
• Start Date: 04-Sep-2025
• Completion Date: 13-Sep-2025

Standards Content (Sample)

FINAL DRAFT
International
Standard
ISO/FDIS 5490
ISO/TC 17/SC 7
Steel — Rating and classifying
Secretariat: AFNOR
nonmetallic inclusions using the
Voting begins on:
scanning electron microscope
2025-07-09
Acier — Classement et classification des inclusions non
Voting terminates on:
métalliques à l'aide du microscope électronique à balayage
2025-09-03
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/FDIS 5490:2025(en) © ISO 2025

FINAL DRAFT
ISO/FDIS 5490:2025(en)
International
Standard
ISO/FDIS 5490
ISO/TC 17/SC 7
Steel — Rating and classifying
Secretariat: AFNOR
nonmetallic inclusions using the
Voting begins on:
scanning electron microscope
Acier — Classement et classification des inclusions non
Voting terminates on:
métalliques à l'aide du microscope électronique à balayage
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2025
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO/FDIS 5490:2025(en) © ISO 2025

ii
ISO/FDIS 5490:2025(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principles . 2
5 Equipment and software . 4
6 Calibration and inspection of equipment . 5
7 Sampling . 5
8 Preparation of specimens . 5
9 Procedure . 5
10 Rating and statistical analysis of inclusions . 7
10.1 Rating method . . .7
10.1.1 Morphology rating method .7
10.1.2 Chemistry rating method .8
10.2 Statistical analysis method .9
11 Test report . 10
Annex A (informative) Typical acquisition analysis rules to be set for SEM analysis.11
Annex B (informative) Example of test results using morphology rating method .12
Annex C (informative) Examples of test results using statistical analysis method . 14
Bibliography . 19

iii
ISO/FDIS 5490:2025(en)
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.
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see 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
FINAL DRAFT International Standard ISO/FDIS 5490:2025(en)
Steel — Rating and classifying nonmetallic inclusions using
the scanning electron microscope
1 Scope
This document specifies procedures for the rating and statistical analysis of non-metallic inclusions
(referred to as inclusions hereafter) using a scanning electron microscope (SEM) with an energy dispersive
X-ray spectrometer (EDS), a backscattered detector (BSD) and automatic image analysis capabilities.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 4967, Steel — Determination of content of non-metallic inclusions — Micrographic method using standard
diagrams
ISO 15632, Microbeam analysis — Selected instrumental performance parameters for the specification and
checking of energy-dispersive X-ray spectrometers (EDS) for use with a scanning electron microscope (SEM) or
an electron probe microanalyser (EPMA)
ISO 16700, Microbeam analysis — Scanning electron microscopy — Guidelines for calibrating image
magnification
ISO 22309, Microbeam analysis — Quantitative analysis using energy-dispersive spectrometry (EDS) for
elements with an atomic number of 11 (Na) or above
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 16700, ISO 22309 and the
following apply.
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/
3.1
maximum Feret’s diameter
maximum distance between the two parallel lines tangent to outer boundary of the particle measured in all
directions, as shown in Figure 1
Note 1 to entry: It is a parameter used to describe the size of irregular particles.

ISO/FDIS 5490:2025(en)
Figure 1 — Schematic of maximum Feret's diameter
3.2
equivalent circle diameter
ECD
diameter of the circle with an area equivalent to the particle
3.3
length
l
dimension of a particle or an inclusion in the main deformation direction, usually larger than the width
3.4
width
w
largest local dimension of a particle or an inclusion perpendicular to the main deformation direction
(“calliper width”)
3.5
aspect ratio
AR
ratio of length to width
3.6
analysis area
certain region of the specimen used to detect inclusions
3.7
rating area
square field of 0,5 mm
Note 1 to entry: It is the specified area of rating inclusions in ISO 4967.
4 Principles
4.1 This document specifies two methods: rating method and statistical analysis method.
4.2 Rating method can use morphology or chemistry as the primary basis for sorting particles into types.
When morphology is mainly used to sort inclusions with chemistry as auxiliary means, it produces the same
ratings as ISO 4967, as illustrated in Figure 2. However, the rating is performed using a fully automated SEM
image analysis system. When agreed by mutual parties, it is also allowed to sort inclusions mainly according
to chemistry, but use morphology as auxiliary means, as illustrated in Figure 3. In this case, it might produce
different ratings from ISO 4967. The two rating methods are called morphology rating method and chemistry

ISO/FDIS 5490:2025(en)
rating method, respectively. The rating method is intended for inclusions larger than 2 micrometre in rolled or
forged steel products with a reduction ratio of at least 3. The rating method used shall be listed in the result.
4.3 Statistical analysis method is used for statistics of inclusions and does not produce ratings as shown
in Figure 4. This method defines procedures to analyse and report inclusions by arbitrary size distribution
and chemical classifications. It may be applied to all size of inclusions in a variety of billets or rolled steels
by appropriate choice of these classifications. Statistical analysis method determines and reports basic
stereological measurements (for example, area fraction of sulfides or oxides, the number of sulfides or oxides
per square millimetre, and so forth).
Figure 2 — Illustration of morphology rating method

ISO/FDIS 5490:2025(en)
Figure 3 — Illustration of chemistry rating method
Figure 4 — Illustration of statistical analysis method
5 Equipment and software
5.1 An automated computer-controlled scanning electron microscope(SEM) shall be equipped, and the
SEM shall have accessories of EDS and backscattered electron (BSE) detector. The resolution of EDS detector
shall conform to ISO 22309. If analysis of carbon, boron, or nitrogen is requested, a light element detector
shall be equipped with a sufficiently thin window to effectively transmit the low energy X rays characteristic
of the elements below sodium.
ISO/FDIS 5490:2025(en)
5.2 The SEM shall have an automated image analysis software. The software shall meet the following
requirements.
a) It shall allow controlling the beam and stage and collecting of i
...

Style Definition
ISO/FDIS 5490(E) .
Formatted: French (Switzerland)
ISO/TC 17/SC 7
Formatted: French (Switzerland)
Secretariat: AFNOR
Date: 2025-05-2606-25
Formatted
...
Steel — Rating and classifying nonmetallic inclusions using the
scanning electron microscope
Acier — Classement et classification des inclusions non métalliques à l'aide du microscope électronique à
balayage
Formatted: English (United Kingdom)
FDIS stage
ISO/FDIS 5490:2025(en)
Formatted: English (United Kingdom)
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
Formatted: French (Switzerland)
E-mail: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO/FDIS 5490:2025(en)
Formatted: English (United Kingdom)
Contents
Foreword . iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principles . 2
5 Equipment and software . 4
6 Calibration and inspection of equipment . 5
7 Sampling . 5
8 Preparation of specimens . 5
9 Procedure . 5
10 Rating and statistical analysis of inclusions . 7
10.1 Rating method . 7
10.1.1 Morphology rating method . 7
10.1.2 Chemistry rating method . 9
10.2 Statistical analysis method . 9
11 Test report . 10
Annex A (informative) Typical acquisition analysis rules to be set for SEM analysis . 11
Annex B (informative) Example of test results using morphology rating method . 12
Annex C (informative) Examples of test results using statistical analysis method . 14
Bibliography . 19

Foreword . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principles . 3
5 Equipment and software . 6
6 Calibration and inspection of equipment . 6
7 Sampling . 7
8 Preparation of specimens . 7
9 Procedure . 7
10 Rating and statistical analysis of inclusions . 9
11 Test report . 11
Annex A (informative) Typical acquisition analysis rules to be set for SEM analysis . 13
Annex B (informative) Example of test results using morphology rating method . 14
Annex C (informative) Examples of test results using statistical analysis method . 17
Bibliography . 24
iii
ISO/FDIS 5490:2025(en)
Formatted: English (United Kingdom)

iv
ISO/FDIS 5490:2025(en)
Formatted: English (United Kingdom)
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.
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents.www.iso.org/patents. ISO shall not be held responsible for identifying any or all such
patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.htmlwww.iso.org/iso/foreword.html.
Formatted: English (United Kingdom)
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.
Formatted: English (United Kingdom)
Formatted: English (United Kingdom)
Field Code Changed
Formatted: English (United Kingdom)
v
ISO/DISFDIS 5490:2025(en)
Formatted
Steel — Rating and classifying nonmetallic inclusions using the
scanning electron microscope
1 Scope
This document specifies procedures for the rating and statistical analysis of non-metallic inclusions (referred
to as inclusions hereafter) using a scanning electron microscope (SEM) with an energy dispersive X-ray
spectrometer (EDS), a backscattered detector (BSD),) and automatic image analysis capabilities.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 4967, Steel — Determination of content of non-metallic inclusions — Micrographic method using standard
diagrams
ISO 15632, Microbeam analysis — Selected instrumental performance parameters for the specification and
checking of energy-dispersive X-ray spectrometers (EDS) for use with a scanning electron microscope (SEM) or
an electron probe microanalyser (EPMA)
ISO 16700, Microbeam analysis — Scanning electron microscopy — Guidelines for calibrating image
magnification
ISO 22309, Microbeam analysis — Quantitative analysis using energy-dispersive spectrometry (EDS) for
elements with an atomic number of 11 (Na) or above
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 16700, ISO 22309 and the following
apply.
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/
3.1
3.1 Maximum
maximum Feret’s diameter
Formatted: English (United Kingdom)
maximum distance between the two parallel lines tangent to outer boundary of the particle measured in all
Formatted: English (United Kingdom)
directions, as shown in Figure 1
Formatted: English (United Kingdom)
Note 1 to entry: It is a parameter used to describe the size of irregular particles.
Formatted: English (United Kingdom)
Formatted: FooterPageNumber
ISO/DISFDIS 5490:2025(en)
Figure 1 — Schematic of Maximummaximum Feret's diameter
Formatted: English (United Kingdom)
Formatted: English (United Kingdom)
3.2 3.2
Formatted: TermNum2
equivalent circle diameter
ECD
diameter of the circle with an area equivalent to the particle
3.3 3.3
Formatted: TermNum2
length
l
dimension of a particle or an inclusion in the main deformation direction, usually larger than the width
3.4 3.4
Formatted: TermNum2, Space Before: 0 pt, After: 0 pt,
width
Adjust space between Latin and Asian text, Adjust space
w between Asian text and numbers
largest local dimension of a particle or an inclusion perpendicular to the main deformation direction (“calliper
width”)
3.5 3.5
Formatted: TermNum2, Space Before: 0 pt, After: 0 pt,
aspect ratio
Adjust space between Latin and Asian text, Adjust space
AR between Asian text and numbers
ratio of length to width
3.6 3.6
Formatted: TermNum2
analysis area
certain region of the specimen used to detect inclusions
Formatted: FooterPageNumber
ISO/DISFDIS 5490:2025(en)
3.7 3.7
Formatted: Dutch (Netherlands)
rating area
Formatted: TermNum2
2 2
square field of 0,5mm 5 mm
Formatted: English (United Kingdom)
Note 1 to entry: It is the specified area of rating inclusions in ISO 4967.
Formatted: English (United Kingdom)
4 Principles
4.1 4.1 This document specifies two methods: rating method and statistical analysis method.
Formatted: Font: 11 pt, Not Bold
Formatted: Font: Not Bold
4.2 4.2 Rating method can use morphology or chemistry as the primary basis for sorting particles into
Formatted: p2
types. When morphology is mainly used to sort inclusions with chemistry as auxiliary means, it produces the
same ratings as ISO 4967, as illustrated in Figure 2. However, the rating is performed using a fully automated
Formatted: Font: 11 pt, Not Bold
SEM image analysis system. When agreed by mutual parties, it is also allowed to sort inclusions mainly
Formatted: Font: Not Bold
according to chemistry, but use morphology as auxiliary means, as illustrated in Figure 3. In this case, it might
produce different ratings from ISO 4967. The two rating methods are called morphology rating method and
Formatted: Font: 11 pt, Not Bold
chemistry rating method, respectively. The rating method is intended for inclusions larger than 2
Formatted: Font: 11 pt, Not Bold, Font color: Auto
micrometer micrometre in rolled or forged steel products with a reduction ratio of at least 3. The rating
method used shall be listed in the result. Formatted: Font: 11 pt, Not Bold
Formatted: Font: Not Bold
4.3 4.3 St
...