Microstructure of cast irons — Part 4: Test method for evaluating nodularity in spheroidal graphite cast irons

This document specifies a test method for evaluating nodularity in spheroidal graphite cast irons by comparative visual analysis and image analysis techniques. This document provides figures for different levels of nodularity and graphite particle count of spheroidal graphite cast irons for visual analysis.

Microstructure des fontes — Partie 4: Méthode d’essai pour l'évaluation de la nodularité des fontes à graphite sphéroïdal

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Status
Published
Publication Date
02-May-2019
Current Stage
6060 - International Standard published
Due Date
17-Sep-2019
Completion Date
03-May-2019
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INTERNATIONAL ISO
STANDARD 945-4
First edition
2019-05
Microstructure of cast irons —
Part 4:
Test method for evaluating nodularity
in spheroidal graphite cast irons
Microstructure des fontes —
Partie 4: Méthode d’essai pour l'évaluation de la nodularité des fontes
à graphite sphéroïdal
Reference number
ISO 945-4:2019(E)
©
ISO 2019

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ISO 945-4:2019(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
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
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Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

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ISO 945-4:2019(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Designations . 2
4.1 Graphite classification by visual analysis . 2
4.2 Graphite classification by image analysis . 3
5 Sampling and sample preparation . 3
6 Procedure for graphite classification . 3
6.1 General . 3
6.2 Procedure for visual analysis . 4
6.3 Procedure for image analysis . 4
6.4 Calculation of nodularity . 4
6.5 Examination fields . 5
6.6 Evaluation of the results . 5
7 Reference images . 5
8 Test report . 5
Annex A (normative) Reference images for nodularity . 7
Annex B (normative) Reference images for graphite particle count .18
Annex C (informative) Roundness of different graphite particles .29
Bibliography .30
© ISO 2019 – All rights reserved iii

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ISO 945-4:2019(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
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 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
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
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 25, Cast irons and pig irons.
A list of all parts in the ISO 945 series can be found on the ISO website.
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 © ISO 2019 – All rights reserved

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ISO 945-4:2019(E)

Introduction
The shape of the graphite particles is an important characteristic of spheroidal graphite cast irons. It
has a critical effect on the mechanical and physical properties of these materials.
© ISO 2019 – All rights reserved v

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INTERNATIONAL STANDARD ISO 945-4:2019(E)
Microstructure of cast irons —
Part 4:
Test method for evaluating nodularity in spheroidal
graphite cast irons
1 Scope
This document specifies a test method for evaluating nodularity in spheroidal graphite cast irons by
comparative visual analysis and image analysis techniques.
This document provides figures for different levels of nodularity and graphite particle count of
spheroidal graphite cast irons for visual analysis.
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 945-1, Microstructure of cast irons — Part 1: Graphite classification by visual analysis
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
maximum Féret diameter
maximum length of an object whatever its orientation
Note 1 to entry: The maximum Féret diameter of a graphite particle is shown in Figure 1.
Key
l maximum Féret diameter of the graphite particle
m
A area of the circle diameter l
m m
A area of the graphite particle
Figure 1 — Illustration of maximum Féret diameter of a graphite particle
© ISO 2019 – All rights reserved 1

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ISO 945-4:2019(E)

3.2
roundness
area of a graphite particle divided by the area of the circle where the diameter is the maximum Féret
diameter (3.1) of the same graphite particle, calculated according to Formula (1):
2
ρ ==AA//4Alπ⋅ (1)
mm
where ρ is the roundness of a graphite particle
3.3
spheroidal graphite
graphite particles classified as form VI and V in accordance with ISO 945-1 or graphite particles with
roundness (3.2) ≥ 0,6 to 1,0
3.4
spheroidal graphite cast iron
cast material, iron, silicon and carbon-based, the carbon being present mainly in the form of spheroidal
graphite (3.3) particles
3.5
nodularity
assessment of the proportion of spheroidal graphite (3.3) particles in a cast iron sample
Note 1 to entry: Nodularity is generally expressed as a percentage.
3.6
graphite particle count
number of graphite particles per unit area
4 Designations
4.1 Graphite classification by visual analysis
To characterize the graphite particles observed, information is generally necessary on the nodularity,
the size and the number of the graphite particles. For this purpose, the following symbols shall be used
at different positions of the designation.
a) Nodularity is designated by a percentage, in increments of five percentage points; see the reference
images of Figure A.1.
NOTE 1 Nodularity of spheroidal graphite cast irons is 50 % as a minimum. Maximum nodularity is
usually about 95 %.
b) Graphite particle size is designated by numbers from 3 to 8 in accordance with ISO 945-1. For
determining the size range, the largest graphite particle in the field of view is used in accordance
with ISO 945-1. If the graphite particles observed in different areas of view cover two sizes,
reference to both is possible in accordance with ISO 945-1.
NOTE 2 The reference images given in ISO 945-1 do not represent all the graphite particle sizes that can
be present in each of the graphite particle size ranges. The reference image schematics in ISO 945-1 show
some graphite particles smaller than the minimum size graphite particles for that size range. The schematics
represent what can be seen when viewing a two-dimensional sectioned view of a three-dimensional
structure where a normal sized particle is sectioned not through its centreline appears smaller than its
actual size.
c) Graphite particle count is designated by numbers; see the reference images of Figure B.1.
EXAMPLE 1 For a spheroidal graphite cast iron, the nodularity, graphite particle size and graphite
2
particle count are 90 %, size 7 and 200 particles/mm , respectively. The structure is described as follows:
2 © ISO 2019 – All rights reserved

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ISO 945-4:2019(E)

2
Nodularity 90 %; size 7; 200 particles/mm .
EXAMPLE 2 For a spheroidal graphite cast iron, the nodularity and graphite particle count are evaluated
2
to be 90 % and 200 particles/mm and the graphite sizes cover size 6 and size 7. The structure is described
as follows:
2
Nodularity 90 %; size 6/7; 200 particles/mm .
The predominant size may be emphasized by underlining the number.
4.2 Graphite classification by image analysis
When a cast iron material is examined using the image analysis method in accordance with
ISO/TR 945-2, the graphite particles should be classified by the following elements.
a) Nodularity, designated by a percentage number calculated according to Formulae (1) and (2). The
results should be reported in whole numbers. For example, 92,6 % is reported as 93 %.
b) Size, designated by numbers from 3 to 8 in accordance with ISO 945-1. For determining the size
range, the largest graphite particle in the field of view is used in accordance with ISO 945-1. If the
graphite particles observed in different fields of view cover two sizes or more, reference to these
size ranges is possible.
c) Graphite particle count, designated by numbers.
EXAMPLE 1 For a spheroidal graphite cast iron, the calculated nodularity, graphite size and graphite
2
particle count are 92,4 %, s
...

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