prEN ISO 4499-2

SLOVENSKI STANDARD oSIST prEN ISO 4499-2:2018 01-september-2018

QMHYHOLNRVWL]UQ7UGLQH0HWDORJUDIVNRGRORþHYDQMHPLNURVWUXNWXUHGHO0HUMH

Hardmetals - Metallographic determination of microstructure - Part 2: Measurement of

Hartmetalle - Metallographische Bestimmung der Mikrostruktur - Teil 2: Messung der WC

Métaux-durs - Détermination métallographique de la microstructure - Partie 2: Mesurage

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms, definitions, abbreviations, symbols and units .................................................................................................. 2

3.1 General ........................................................................................................................................................................................................... 2

3.2 Terms and definitions ....................................................................................................................................................................... 2

3.3 Symbols, abbreviations and units ........................................................................................................................................... 3

4 General information ......................................................................................................................................................................................... 4

5 Apparatus ..................................................................................................................................................................................................................... 5

6 Calibration .................................................................................................................................................................................................................. 5

7 Grain-size measurement by the linear-intercept method ......................................................................................... 6

7.1 General ........................................................................................................................................................................................................... 6

7.2 Sampling ....................................................................................................................................................................................................... 6

7.2.1 Sampling of products ................................................................................................................................................... 6

7.2.2 Sampling of microstructure .................................................................................................................................... 7

7.3 Measurement errors .......................................................................................................................................................................... 7

7.3.1 Systematic and random errors ............................................................................................................................ 7

7.3.2 Large WC grain sizes..................................................................................................................................................... 8

7.3.3 Smallest measurable intercept ............................................................................................................................ 8

8 Reporting ...................................................................................................................................................................................................................... 9

Annex A (informative) Measurement case study ..................................................................................................................................10

Annex B (informative) Report proforma .......................................................................................................................................................15

Bibliography .............................................................................................................................................................................................................................17

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

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

Any trade name used in this document is information given for the convenience of users and does not

For an explanation on 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 the following

This document was prepared by Technical Committee ISO/TC 119, Powder metallurgy, Subcommittee

This third edition cancels and replaces the second edition (ISO 4499-2:2008), which has been technically

— Clause 7.3.3, Table 1, row "Electron Back Scatter Diffraction" added and in row "Scanning electron

microscope" the value for the "Minimum visible intercept length" corrected from 200 nm into 400 nm.

This document gives guidelines for the measurement of hardmetal grain size by metallographic

techniques only using optical or electron microscopy. It is intended for sintered WC/Co hardmetals

(also called cemented carbides or cermets) containing primarily WC (de: Wolframcarbid, en: tungsten

carbide) as the hard phase. It is also intended for measuring the grain size and distribution by the

— linear analysis techniques, to acquire sufficient statistically meaningful data;

This document is supported by a measurement case study to illustrate the recommended techniques

— Recommendations on shape measurements. Further research is needed before recommendations

Measurements of coercivity are sometimes used for grain-size measurement, but this current guide is

concerned only with a metallographic measurement method. It is also written for sintered hardmetals

and not for characterising powders. However, the method could, in principle, be used for measuring the

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 3369, Impermeable sintered metal materials and hardmetals — Determination of density

ISO 3738-2, Hardmetals — Rockwell hardness test (scale A) — Part 2: Preparation and calibration of

ISO 4499-1, Hardmetals — Metallographic determination of microstructure — Part 1: Photomicrographs

ISO 4499-4, Hardmetals — Metallographic determination of microstructure — Part 4: Characterisation of

A very wide range of terms are used to describe powders or sintered hardmetals of different sizes. For

None of these terms have commonly agreed or well-defined size ranges among users and producers of

Consequently, following discussion in the hardmetal community, the following terms for the sizes

The uncertainty associated with the measurement of linear-intercept grain size is about 10 %, if

typically (200 to 300) grains are counted. Thus, measurements on or close to the class boundaries

should be treated carefully. It is recommended that measurements that fall within 10 % of any of the

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

Note 1 to entry: Measured by the mean-linear-intercept method described in this document.

Note 1 to entry: Measured by the mean-linear-intercept method described in this document.

Note 1 to entry: Measured by the mean-linear-intercept method described in this document.

Note 1 to entry: Measured by the mean-linear-intercept method described in this document.

Note 1 to entry: Measured by the mean-linear-intercept method described in this document.

Note 1 to entry: Measured by the mean-linear-intercept method described in this document.

Note 1 to entry: Measured by the mean-linear-intercept method described in document.

For the purposes of this document, the following symbols, abbreviations and units apply.

This part of ISO 4499 addresses the issue of good practice for the measurement of a mean value for WC

grain size. It recommends the use of a linear-intercept technique for obtaining data. The measurements

shall be made using good practice for the preparation of suitable microstructures for examination

The properties and performance of hardmetals are directly dependent on the microstructure developed

during manufacture, which in turn is controlled by the character of the starting powder batch.

Understanding the microstructure is the key to controlling or improving properties, and therefore the

measurement of microstructural features, particularly grain size and size distribution, is of paramount

Methods of metallographic preparation and etching techniques are as important as the grain-size

measurement method (see [1] to [4]), and are included in ISO 4499-1. The principal type of hardmetal

considered is WC with a Co binder. However, the procedure can be used for hardmetals that contain

The most direct way to measure the WC grain size is to polish and etch a cross-section of the

microstructure and then to use quantitative metallographic techniques to measure a mean value for

There are three ways by which the mean size by number of the WC grains can be defined:

A number average is obtained by counting each measurement of the parameter of interest (length, area

or volume) and dividing the total value of the parameter (length, area or volume) by the number of this

The value most used to date has been a length parameter. This can be obtained in several ways, for

— by linear intercept, called the Heyn method, from a straight line drawn across the structure;

— by the equivalent circle diameter; this is obtained by measuring grain areas and then taking the

diameter of a circle of equivalent area. It is possible, for equiaxed grains, to convert an equivalent

circle diameter (ECD) grain size to a linear intercept (LI) value using Equation (1).

An additional method is that established by Jefferies, where the number of grains per unit area can be

— the Jefferies method is not intended for use on multiphase materials such as hardmetals.

The recommended technique for measurement of hardmetal grain size is the linear-intercept method.

Grain-size measurements are obtained from images of the microstructure. ISO 4499-1, ASTM B657

and ASTM B665 should be consulted for best practice in the preparation of surfaces for imaging.

Hardmetal structural images are usually generated by either optical microscopy, scanning electron

microscopy (SEM) or Electron Back Scatter Diffraction (EBSD). For accurate measurements, it is better

to use scanning electron-microscopic images. Even in coarse-grained materials, the imaged surface

cuts through a substantial number of the corners of grains, giving a proportion of small intercepts that

Measurements of intercept lengths from the acquired images can be obtained manually or

semiautomatically using image analysis. Automatic image analysis can be used in some circumstances

when the images are fairly coarse and good contrast can be obtained, but for many materials, especially

those with very fine grain sizes, good images are difficult to acquire and are generally not amenable to

For the ultrafine and nano grades, good images are particularly difficult to acquire using conventional

scanning electron microscopes with tungsten-filament electron sources. For these materials, it is

recommended that a field emission SEM (FESEM) be used. These systems give significantly higher

resolution images, sufficient to measure materials with mean intercept sizes of about 0,1 µm to 0,2 µm.

For materials with ever smaller grain sizes, it may be necessary to use transmission electron microscopy

(TEM). However, the problems of sampling and specimen preparation are particularly severe (see [7]).

Careful specimen preparation for good images is vital for these materials, and often a combination of

To give reliable quantitative measurements, images shall be calibrated against a stage micrometer or