SIST EN ISO 13383-1:2016

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01-junij-2016
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Fine ceramics (advanced ceramics, advanced technical ceramics) - Microstructural
characterization - Part 1: Determination of grain size and size distribution (ISO 13383-
1:2012)
Hochleistungskeramik - Mikrostrukturelle Charakterisierung - Teil 1: Bestimmung der
Korngröße und der Korngrößenverteilung (ISO 13383-1:2012)
Céramiques techniques - Caractérisation microstructurale - Partie 1: Détermination de la
grosseur du grain et de la distribution granulométrique (ISO 13383-1:2012)
Ta slovenski standard je istoveten z: EN ISO 13383-1:2016
ICS:
81.060.30 Sodobna keramika Advanced ceramics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 13383-1
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2016
EUROPÄISCHE NORM
ICS 81.060.30 Supersedes EN 623-3:2001
English Version
Fine ceramics (advanced ceramics, advanced technical
ceramics) - Microstructural characterization - Part 1:
Determination of grain size and size distribution (ISO
13383-1:2012)
Céramiques techniques - Caractérisation Hochleistungskeramik - Mikrostrukturelle
microstructurale - Partie 1: Détermination de la taille Charakterisierung - Teil 1: Bestimmung der Korngröße
et de la distribution des grains (ISO 13383-1:2012) und der Korngrößenverteilung (ISO 13383-1:2012)
This European Standard was approved by CEN on 18 March 2016.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 13383-1:2016 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
European foreword
The text of ISO 13383-1:2012 has been prepared by Technical Committee ISO/TC 206 “Fine ceramics”
of the International Organization for Standardization (ISO) and has been taken over as EN
ISO 13383-1:2016 by Technical Committee CEN/TC 184 “Advanced technical ceramics” the secretariat
of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by October 2016, and conflicting national standards shall
be withdrawn at the latest by October 2016.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
This document supersedes EN 623-3:2001.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 13383-1:2012 has been approved by CEN as EN ISO 13383-1:2016 without any
modification.
INTERNATIONAL ISO
STANDARD 13383-1
First edition
2012-09-01
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Microstructural characterization —
Part 1:
Determination of grain size and size
distribution
Céramiques techniques — Caractérisation microstructurale —
Partie 1: Détermination de la grosseur du grain et de la distribution
granulométrique
Reference number
ISO 13383-1:2012(E)
©
ISO 2012
ISO 13383-1:2012(E)
© ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any
means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the
address below or ISO’s member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved

ISO 13383-1:2012(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Significance and use . 3
5 Apparatus . 4
5.1 Sectioning equipment . 4
5.2 Mounting equipment . 4
5.3 Grinding and polishing equipment . 4
5.4 Etching equipment. 4
5.5 Microscope . 4
5.6 Calibrated rule or scale . 5
5.7 Circle template . 5
6 Test piece preparation . 5
6.1 Sampling . 5
6.2 Cutting . 5
6.3 Mounting . 5
6.4 Grinding and polishing . 5
6.5 Etching . 6
7 Photomicrography . 6
7.1 General aspects . 6
7.2 Optical microscopy . 6
7.3 Scanning electron microscopy . 6
7.4 Calibration micrographs . 7
8 Measurement of micrographs . 7
8.1 General . 7
8.2 Method A1 . 8
8.3 Method A2 . 8
8.4 Method B . 8
8.5 Use of automatic or semi-automatic image analysis for methods A and B . 9
9 Calculation of results .10
9.1 Method A1 .10
9.2 Method A2 .10
9.3 Method B .10
10 Interferences and uncertainties .11
11 Test report .12
Annex A (informative) Grinding and polishing procedures .14
Annex B (informative) Etching procedures .16
Annex C (informative) Setting Köhler illumination in an optical microscope .18
Annex D (informative) Round-robin verification of Method A1.19
Annex E (informative) Round-robin verification of Method B .20
Annex F (informative) Grain size distribution measurement .21
Annex G (informative) Results sheet: Grain size in accordance with ISO 13383-1 .22
Bibliography .23
ISO 13383-1:2012(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
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.
ISO 13383-1 was prepared by Technical Committee ISO/TC 206, Fine ceramics.
ISO 13383 consists of the following parts, under the general title Fine ceramics (advanced ceramics,
advanced technical ceramics) — Microstructural characterization:
— Part 1: Determination of grain size and size distribution
— Part 2: Determination of phase volume fraction by evaluation of micrographs
iv © ISO 2012 – All rights reserved

INTERNATIONAL STANDARD ISO 13383-1:2012(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Microstructural characterization —
Part 1:
Determination of grain size and size distribution
1 Scope
This part of ISO 13383 describes manual methods of making measurements for the determination of
grain size of fine ceramics (advanced ceramics, advanced technical ceramics) using photomicrographs
of polished and etched test pieces. The methods described in this part do not yield the true mean grain
diameter, but a somewhat smaller parameter depending on the method applied to analyse a two-
dimensional section. The relationship to true grain dimensions depends on the grain shape and the
degree of microstructural anisotropy. This part contains two principal methods, A and B.
Method A is the mean linear intercept technique. Method A1 applies to single-phase ceramics, and to
ceramics with a principal crystalline phase and a glassy grain-boundary phase of less than about 5 % by
volume for which intercept counting suffices. Method A2 applies to ceramics with more than about 5 %
by volume of pores or secondary phases, or ceramics with more than one major crystalline phase where
individual intercept lengths are measured, which can optionally be used to create a size distribution.
This latter method allows the pores or phases to be distinguished and the mean linear intercept size for
each to be calculated separately.
NOTE A method of determining volume fraction(s) of secondary phase(s) can be found in ISO 13383:2; this
will provide a means of determining whether Method A1 or Method A2 should be applied in borderline cases.
Method B is the mean equivalent circle diameter method, which applies to any type of ceramic with or
without a secondary phase. This method may also be employed for determining grain aspect ratio and
a size distribution.
Some users of this part of ISO 13383 may wish to apply automatic or semiautomatic image analysis to
micrographs or directly captured microstructural images. This is permitted by this part provided that
the technique employed simulates the manual methods (see Clause 4 and 8.4).
2 Normative references
The following referenced documents are indispensable for the application 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/IEC 17025, General requirements for the competence of testing and calibration laboratories
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
grain size
size of the distinct crystals in a material, and for the purposes of this method of test, that of the primary
or major phase
ISO 13383-1:2012(E)
3.2
mean linear intercept grain size
g
mli
average value of the distance between grain boundaries as shown by randomly positioned lines drawn
across a micrograph or other image of the microstructure
3.3
equivalent circle grain diameter
d
ci
diameter of a circle which closely matches the perimeter of a grain
See Figure 1.
3.4
maximum (Feret) grain size
d
ci, max
maximum dimension of a grain viewed in two dimensions
See Figure 1.
NOTE This is also termed maximum caliper diameter in ASTM E930.
3.5
maximum orthogonal grain size
d
ci, perp
for the purposes of determination of grain aspect ratio, the largest dimension of a grain normal to its
maximum (Feret) grain dimension, viewed in two dimensions
See Figure 1.
3.6
grain aspect ratio
ratio of maximum (Feret) grain size to the maximum orthogonal grain size measured perpendicular to it
2 © ISO 2012 – All rights reserved

ISO 13383-1:2012(E)
Key
1 Equivalent circle grain diameter, d
ci
2 Maximum grain (Feret) size, d
ci, max
3 Maximum orthogonal grain size perpendicular to 2, d
ci, perp
Figure 1 — Equivalent circle diameter and definition of aspect ratio
4 Significance and use
The mean grain size and the distribution of grain sizes of a ceramic material play an important role in
determining many properties, and thus grain size characterization is an important tool for ensuring
consistency of manufacture. There are many measures of grain size and/or shape, and these are usually
of different numerical values for a given microstructure.
NOTE The Bibliography contains sources dealing with stereology and methods of sizing three-
dimensional objects.
The principal purpose of this part of ISO 13383 is to permit characterization of the major phases.
However, in materials which contain more than one phase, the phases may be continuous or as isolated
grains. It may be necessary to characterize the different phases separately. The same intercept principle
as for single-phase materials can be used, but the individual intercept lengths across each phase must
be measured, rather than just counted. The characterization of minor phases may require different
treatment, which is outside the scope of this part of ISO 13383.
Method A, the linear intercept method, provides the simplest possible method from a two-dimensional
section through the material. However, it must be recognized that the numerical value obtained for
the mean linear intercept size is somewhat smaller than most other measures of grain size because
intercepts can cross grains at any position, and not necessarily along the largest axis. The relationship
between mean linear intercept size and a true three-dimensional grain size is not simple, and depends
on the grain shape and the average number of facets. This part of ISO 13383 provides simple methods of
measuring intercept distances in single-phase materials based on counting the number of intersections
along given lengths of randomly orientated and positioned lines or randomly positioned circles drawn
onto a micrograph of a suitably sectioned, polished and etched test piece. The length of lines crossing
large pores residing at grain boundaries can be ignored, thus eliminating any bias that porosity may
introduce, but small pores within grains should be ignored.
ISO 13383-1:2012(E)
Method B, the mean equivalent circle diameter method, provides an alternative approach based on
identifying the radius of a circle which most closely approximates the boundary of the grain. This
measure usually gives a result which is a little larger than that from the mean linear intercept method
because it is based on area and not random intercept length. The method may also be used to measure
grain aspect ratio, and is therefore more appropriate for microstructures with elongated grains.
[1]
NOTE This method is taken from JIS R1670 .
If the material possesses a microstructure which has a preferred orientation of the primary or
secondary phases, the results of this measurement may not be representative of the true character of
the material. Rather than using randomly orientated lines, it may be necessary to make measurements
restricted to specific orientations. If undertaken, this must be reported in the Test Report. Method B
may be more appropriate.
This part of ISO 13383 does not cover methods of measuring mean grain size by counting using calibrated
microscope stage movement or projection onto screens, accompanied by visual observation. While this
latter method may produce an equivalent result to the analysis of micrographs, it does not provide a
means of verification of the results of the measurement, since no permanent record is obtained.
If automatic or semiautomatic image analysis (AIA) is to be used, it must be recognized that different
AIA systems approach the measurement in different ways, usually based on pixel counting. In order
to obtain results equivalent to those of the manual methods described in this part of ISO 13383, the
AIA system needs to be programmed to operate in a similar way to the manual method. By agreement
between the parties concerned, such a near-equivalent AIA method may be used as an alternative to the
manual method, and if undertaken must be reported in the Test Report.
5 Apparatus
5.1 Sectioning equipment
A suitable fine-grained diamond-bladed cut-off saw with a liquid cooling or other device to prepare the
initial section for investigation.
[2]
NOTE A grit size of 125 µm to 150 µm is recommended, designated as D151 in ISO 6106 .
5.2 Mounting equipment
Suitable metallurgical mounting equipment and media for providing firm gripping of the test pieces
for polishing.
5.3 Grinding and polishing equipment
Suitable grinding and polishing equipment, employing diamond abrasive media.
NOTE Annex A recommends techniques and abrasives.
5.4 Etching equipment
Etching equipment appropriate to the etching process to be used to reveal grain boundaries in the
material being examined.
NOTE Annex B provides some guidelines for etching methods.
5.5 Microscope
An optical or scanning electron microscope with photomicrographic facilities. A calibrated stage
micrometer is required for determination of magnification in an optical microscope, and a reference
square grid or latex spheres are required for calibration of magnification in a scanning electron
4 © ISO 2012 – All rights reserved

ISO 13383-1:2012(E)
microscope. In all cases, the calibration of dimensions of the references shall be traceable to national or
international standards of length measurement.
An optical microscope is additionally required for assessing the quality of polishing (see 6.4).
5.6 Calibrated rule or scale
A calibrated rule or scale reading to 0,5 mm or better, and accurate to 0,5 % or better.
5.7 Circle template
For method B, a stencil cut with circles of diameter in 1 mm increments, or a transparent sheet with circles
drawn in a series of 1 mm increments. The line thickness on a transparent sheet shall not exceed 0,2 mm.
6 Test piece preparation
6.1 Sampling
The test pieces shall be sampled in a manner subject to agreement between the parties concerned.
NOTE Guidance on this issue may be found in EN 1006 (see Bibliography [3]). Depending on the objectives
of the measurement, it is desirable to maintain full knowledge of the positions within components or test pieces
from which sections are prepared.
6.2 Cutting
The required section of the test piece shall be cut using the sectioning device (see 5.1).
NOTE For routine inspection of materials, a small area of not more than 10 mm side is normally adequate as
the section to be polished.
6.3 Mounting
Mount the test piece using an appropriate mounting medium. If the ceramic is suspected to have
significant open porosity in some regions (see Clause 1), it is advisable to vacuum impregnate the test
piece with liquid mounting resin before encapsulating as this will provide some support during polishing.
NOTE It is not essential to encapsulate the test piece. For example, it could be affixed to a metal holder.
However, encapsulation in a polymer-based medium allows easy gripping and handling, especially of small
irregularly shaped test pieces and of weak, friable materials. The method of mounting selected should take into
account the etching procedure to be used; see Annex B.
6.4 Grinding and polishing
Grind and polish the surface of the test piece. Care should be taken to ensure that grinding produces
a planar surface with a minimum of damage. Employ successively smaller grit sizes, at each stage
removing the damage from the previous stage until there is no change in appearance when examined by
an optical microscope (see 5.5) at high magnification. The final surface shall be free from optically visible
scratches, or other damage introduced by polishing, which would interfere with the determination.
NOTE Care should be taken in choosing the sequence of grits and lap types. It is impossible within the scope
of this part of ISO 13383 to make specific recommendations for all types of material. The general principle to be
adopted is the minimization of subsurface damage, and its removal by progressively finer grits while retaining a
flat surface. Some guidelines on grinding and polishing are given in Annex A.
ISO 13383-1:2012(E)
6.5 Etching
When a good quality surface has been achieved, the test piece shall be etched if necessary to reveal grain
boundaries. Any suitable technique appropriate to the ceramic material class shall be used, subject to
agreement between the parties concerned. Excessive intensity of etching shall be avoided.
NOTE Some general guidelines recommending etching procedures for various commonly available advanced
technical ceramics are given in Annex B.
7 Photomicrography
7.1 General aspects
Either optical microscopy or scanning electron microscopy may be used, the latter being required if the
grain structure is on a scale finer than can be resolved adequately by optical microscopy, according to
the requirements for the minimum observed sizes of grains or second phases in the prepared images.
NOTE Typically, if the mean linear intercept size of the principal phase is less than about 2 µm for Method A1,
or less than about 4 µm for Methods A2 and B, then scanning electron microscopy should be used.
7.2 Optical microscopy
Set up Köhler illumination in the microscope.
NOTE 1 Guidance on setting up Köhler illumination is given in Annex C.
Examine the test piece at a magnification sufficient to resolve the individual grains clearly. If the contrast
obtained is insufficient, e.g. in white or translucent materials, apply a suitable thin metallic coating by
evaporation or sputtering. Prepare micrographs of at least three different areas of the test piece surface.
NOTE 2 The important aspect of area selection is that it should be random and representative of the test
material. Depending on the purpose of the investigation, it should be agreed between the parties concerned
whether it is more important to employ several images from a single polished sample, or individual images from
a number of samples in a batch. Furthermore, if the material appears to be inhomogeneous, or to have a wide
distribution of grain sizes, it may be advantageous to evaluate more areas less intensively than in the case of a
very uniform microstructure.
As a guideline for Method A, the average size of each distinct grain should appear at least 2 mm and
preferably at least 3 mm across in the evaluated image. For Method B, the typical size of discrete phase
areas or pores should appear at least 5 mm across. If the grains or phase areas appear smaller than
these levels, increase the magnification and prepare fresh micrographs. Printed micrographs should be
typically of a size at least 100 mm x 75 mm, but may with advantage be enlarged to aid evaluation.
7.3 Scanning electron microscopy
Mount the test piece on the test piece holder of the microscope. If the test piece is not electrically
conducting, apply a thin evaporated or sputtered conductive coating. Insert the test piece into the
microscope, ensuring that the surface to be characterized is normal to the electron beam to within 5°.
NOTE 1 This ensures that the image does not suffer from excessive distortion or loss of focus due to the
angle of viewing.
Prepare micrographs at a suitable magnification (see 7.2) from at least three different areas of the test
piece, using the same visual guidelines as for optical images.
NOTE 2 The appearance of micrographs may vary depending on the accelerating voltage employed. Voltages of
less than 15 kV may be advantageous in improving contrast.
6 © ISO 2012 – All rights reserved

ISO 13383-1:2012(E)
7.4 Calibration micrographs
7.4.1 Optical microscopy
For optical microscopy, unless already undertaken, prepare a micrograph of a calibrated stage
micrometer at the same magnification as that used for preparing micrographs in order to provide a
calibration of magnification. Measure the size of the spacing of the calibrated stage micrometer as
shown by a micrograph and calculate the magnification.
7.4.2 Scanning electron microscopy
For calibration of the lateral (X-direction) and vertical (Y-direction) magnifications of the scanning
electron micrographs, prepare similar images of a calibrated grid, or of calibrated spheres, at the same
operating voltage and working distance of the microscope stage as that used for taking micrographs.
NOTE The photographic screen or image capture system in the microscope may not have constant
magnification at all points. A square grid makes a suitable reference for ascertaining the degree of distortion
in the field of view, since it is easy to detect distortions of the grid. If the image distortion is uniform across the
field of view, i.e. X and Y magnifications appear to be constant but different, it is possible to make corrections
when measuring the micrographs. The effective magnification of each drawn line (see 8.2) can be calculated
by noting its angle relative to the X direction on the micrographs and applying an angular correction to the X
direction magnification. This procedure may only be adopted by agreement between the parties concerned, and
be reported (see Clause 11).
Use the same procedure as for optical micrographs (see 7.4.1) to calculate the X and Y direction
magnifications. If calibration spheres have been used, measure the horizontal and vertical dimensions
of at least six spheres and calculate the respective mean values. If the calculated X and Y direction
magnifications are different by more than 5 % or individually vary by more than 5 % across the screen,
the distortion of the image is not acceptable for the purposes of this part of ISO 13383.
8 Measurement of micrographs
8.1 General
Inspect the micrographs. If they appear to be essentially single phase and to contain less than 5 % of a
secondary phase, use Method A1 or Method B. If they appear to contain 5 % or more of a secondary phase,
either continuous or as discrete grains, employ the procedure given in Method A2 as an alternative to A1.
If the requirement is for determining additionally a grain size distribution, use Method A2 or Method B.
Whichever method is employed, the confidence in the average grain size determination depends on the
spread of apparent grain sizes and the number of independent grain dimensions measured. For a single-
phase ceramic with visually uniform and isotropic size and shape of grains, counting about 100 grains
or grain intercepts in total over all micrographs employed will provide an estimate of average grain
size to within about ±10 % of the true average. For ceramics which do not meet this criterion, a larger
number of grains or grain intercepts generally needs to be counted to achieve this level of confidence. If
a more accurate estimate is required, a larger number of grains or grain intercepts needs to be counted.
Thus, for routine quality control purposes on a uniform-grained material which has demonstrable
consistency, counting about 100 grains in total over three representative areas may be sufficient. For a
material with initially unknown microstructure, or which may be multiphase, or which has a preferred grain
orientation or a wide grain size distribution, typically 300, perhaps 500, grains in total may be required.
NOTE 1 For some applications, it may be more important to sample systematically a large number of test items
or areas within a test piece rather than focus on the minimum of three randomly selected areas.
NOTE 2 If it is uncertain whether sufficient grains or grain intercepts have been counted, a ‘cumulative moving
average’ size should be computed as the count proceeds. Plotting the cumulative moving average against the
number of grains or intercepts counted provides a visual trend of progress towards a stable final result within
the uncertainty band required for the estimate.
ISO 13383-1:2012(E)
Methods A1 (see 8.2), A2 (see 8.3) and B (see 8.4) are intended for manual measurement of printed
micrographs of a material treated as ‘unknown’ and requiring precautions in measurement. Additional
factors when using semi-automatic or fully automatic image analysis systems are described in 8.5. The
described requirement for at least five randomly orientated drawn lines in Methods A1 and A2 may,
with justification, be appropriately relaxed when the material is known to be of uniform, isotropic
and consistent microstructure. Similarly, the total number of intersections or grains counted may be
reduced, but in no case shall less than 100 features be counted (a minimum of 30 per micrograph).
8.2 Method A1
Unless otherwise justified, draw at least five thin straight lines of random position and orientation
across each micrograph intersecting at least 100, preferably up to 300, grains in total over the minimum
of three micrographs.
NOTE 1 On a micrograph of typical size 100 mm x 75 mm showing grains averaging 3 mm across satisfying
the requirements of 7.1, five lines of length 75 mm will provide an adequate number of grain intersections for
this test method.
NOTE 2 Random orientation of the lines ensures that the influence of any texture, local or general, is minimized.
Measure each line length to the nearest 0,5 mm using the calibrated rule or scale (see 5.6) and calculate
the total line length L(t). Count the number N(i) of intersections of the lines with grain boundaries. If the
line intersects the junction of three grains, count this as 1,5 intersections. If the line intersects a large
pore, a wide grain boundary, or a minor secondary phase, either discrete or continuous, count this as
one intersection. Measure the total length of line that crosses large pores or inclusions, L(p). If the line
runs exactly along a grain boundary, count this as one intersection.
Alternatively, on each micrograph draw at least three circles of diameter not less than 10 times the
expected mean grain size, using a pair of compasses and randomly positioning the circle centres.
Measure the diameters of the circles d to the nearest 0,5 mm using the calibrated rule or scale (see 5.5),
and calculate the sum of their circumferences L(t). Count the number N(i) of intersections of each circle
with the grain boundaries. If the intersection coincides with the junction of three grains, count this as
1,5 intersections. If the line intersects a large pore, a wide grain boundary, or a minor secondary phase,
either discrete or continuous, count this as one intersection. Measure the approximate arc length that
crosses large pores L(p).
NOTE 3 For the purposes of this part of ISO 13383, a large pore is one which resides at grain boundaries. Small
pores entrained within grains should be ignored.
8.3 Method A2
Unless otherwise justified, draw at least five randomly positioned and randomly orientated straight lines
across each micrograph such that a total of at least 100, preferably up to 300, discrete phase regions or
pores of the type to be assessed are intersected. Ignore grains which touch the edge of the micrograph.
Using a visual aid as necessary, measure the distance, L , between intersections of grain boundaries
i
across each phase region or pore to the nearest 0,5 mm using the calibrated rule or scale (see 5.6). Count
the total number of phase regions or pores, N(g), measured.
8.4 Method B
Overlay the micrographs in turn with the stencil or transparent sheet. For each complete grain in the
micrograph (i.e. ignoring grains intersected by the micrograph border), identify the circle that best fits
the boundary of the grain using the visual criterion that approximately equal areas of grain should be
inside the circle as outside (see Figure 2). Note the circle diameter. All complete grains in the micrographs
shall be measured. At least 100 grains, preferably up to 300, shall be measured.
If it is required to measure the grain aspect ratio, use the same procedure, but for each grain match the
circles to the longest (Feret) grain diameter and to the maximum grain diameter perpendicular to the
longest grain diameter (see Figure 1). Note these diameters. Alternatively, a calibrated rule may be used.
8 © ISO 2012 – All rights reserved

ISO 13383-1:2012(E)
Figure 2 — Use of a stencil, 1, overlaid on a micrograph, 2, and visually matched to the selected
grain being measured.
8.5 Use of automatic or semi-automatic image analysis for methods A and B
If it is desired to apply an automatic or semi-automatic image analyser to the measurement of micrographs
or directly recorded images, in order that the results are comparable with the manual method described
in this part of ISO 13383, the following points are to be noted:
a) Care must be taken that the contrast change at a grain boundary is sufficient for the detection
system to identify it as such. If the captured image requires enhancement in order to reveal grain
boundaries more clearly, this should be performed manually rather than using any proprietary
software until confidence is built up that the software method produces equivalent results.
b) For Methods A1 and A2, the image should be line-scanned in at least five random directions, which
may be achieved either through software design or by rotating the image to random orientations
and taking horizontal line scans. Scanning in only one direction on the test piece is not generally
acceptable since it does not allow for anisotropy unless justified by inspection.
c) The equivalent image analysis approach to Method B is to measure individual grain areas that do
not intersect the edges of the micrographs, using pixel counting, and then to compute individual
equivalent circle diameters. Care is needed to ensure uniform contrast across each grain and
narrow grain boundaries, otherwise an underestimate of grain size will result.
d) The analyser must be calibrated for magnification using micrographs or images of a graticule or
grid, as for the manual methods.
e) The calculation routine incorporated in the software must operate in the same way as this manual
method in order that large pores are discounted.
f) The Test Report shall contain full documentation of the procedure employed.
NOTE Failure to observe these points will produce results which may be substantially at variance with the
manual method.
ISO 13383-1:2012(E)
9 Calculation of results
9.1 Method A1
For both line and circle methods, calculate the mean linear intercept distance, g , expressed in
mli
micrometres, for each micrograph using the equation:
L (t)(- L p) ×10
[]
g = (1)
mli
N (i)× m
where
L(t) is the total line length expressed in millimetres; in the case of circles, the total circum-
ference of the circles, expressed in millimetres;
L(p) is the total line length that crosses large pores or inclusions, expressed in millimetres;
N(i) is the counted number of intersections on each micrograph;
m is the calibrated magnification of the micrograph.
Calcul
...