FprEN ISO 643
(Main)Steel - Micrographic determination of the apparent grain size (ISO/FDIS 643:2015)
Steel - Micrographic determination of the apparent grain size (ISO/FDIS 643:2015)
2020-11-26: WI cancelled. CEN/BT C218/2020
2020-11-16: Request to BT to cancel this WI circulated on 2020-10-28
2019-09-16: TC will launch CIB to withdraw this WI, then a BT decision is needed to drop positive voting results
2016-02-09: WI ON HOLD - ISO WI cancelled at ISO level - ECISS/TC to advise on the future of this project at CEN level.
Stahl - Mikrophotographische Bestimmung der erkennbaren Korngröße (ISO/FDIS 643:2015)
Acier - Détermination micrographique de la grosseur de grain apparente (ISO/FDIS 643:2015)
Jekla - Mikrografsko ugotavljanje navidezne velikosti kristalnih zrn (ISO/FDIS 643:2015)
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Standards Content (Sample)
SLOVENSKI STANDARD
01-junij-2015
Jekla - Mikrografsko ugotavljanje navidezne velikosti kristalnih zrn (ISO/FDIS
643:2015)
Steel - Micrographic determination of the apparent grain size (ISO/FDIS 643:2015)
Acier - Détermination micrographique de la grosseur de grain apparente (ISO/FDIS
643:2015)
Ta slovenski standard je istoveten z: FprEN ISO 643
ICS:
77.040.99 Druge metode za Other methods of testing of
preskušanje kovin metals
77.080.20 Jekla Steels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 643
ISO/TC 17/SC 7
Steel — Micrographic determination
Secretariat: AFNOR
of the apparent grain size
Voting begins on:
201504 02
Acier — Détermination micrographique de la grosseur de grain
apparente
Voting terminates on:
201506 02
Please see the administrative notes on page iii
RECIPIENTS OF THIS DRAFT ARE INVITED TO
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OF ANY RELEVANT PATENT RIGHTS OF WHICH
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DOCUMENTATION.
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Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
ISO/FDIS 643:2015(E)
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. ISO 2015
ISO/FDIS 643:2015(E)
© ISO 2015
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ii © ISO 2015 – All rights reserved
ISO/FDIS 643:2015(E)
ISO/CEN PARALLEL PROCESSING
This final draft has been developed within the International Organization for Standardization (ISO), and pro
cessed under the ISO-lead mode of collaboration as defined in the Vienna Agreement. The final draft was
established on the basis of comments received during a parallel enquiry on the draft.
This final draft is hereby submitted to the ISO member bodies and to the CEN member bodies for a parallel
twomonth approval vote in ISO and formal vote in CEN.
Positive votes shall not be accompanied by comments.
Negative votes shall be accompanied by the relevant technical reasons.
ISO/FDIS 643:2015(E)
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 2
5 Principle . 2
6 Selection and preparation of the specimen . 5
6.1 Test location . 5
6.2 Revealing ferritic grain boundaries . 5
6.3 Revealing austenitic and prioraustenitic grain boundaries . 5
6.3.1 General. 5
6.3.2 “Bechet-Beaujard” method by etching with aqueous saturated picric
acid solution . . 5
6.3.3 “Kohn” method by controlled oxidation . 6
6.3.4 “McQuaid-Ehn” method by carburization at 925 °C . 7
6.3.5 Proeutectoid ferrite method . 8
6.3.6 Bainite or gradientquench method . 8
6.3.7 Sensitization of austenitic stainless and manganese steels . 9
6.3.8 Other methods for revealing prioraustenitic grain boundaries . 9
7 Characterization of grain size . 9
7.1 Characterization by an index . 9
7.1.1 Formulae . 9
7.1.2 Assessment by comparison with standard grain size charts .10
7.1.3 Planimetric method .10
7.1.4 Estimation of the index .10
7.2 Characterization by the intercept method .10
7.2.1 Linear intercept segment method .11
7.2.2 Circular intercept segment method .12
7.2.3 Assessment of results .13
8 Test report .14
Annex A (informative) Summary of methods for revealing ferritic, austenitic, or prior-
austenitic grain boundaries in steels .15
Annex B (normative) Determination of grain size — Standard charts taken from ASTM E112 .16
Annex C (normative) Evaluation method .31
Bibliography .37
iv © ISO 2015 – All rights reserved
ISO/FDIS 643:2015(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 on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 17, Steel, Subcommittee SC 7, Methods of testing
(other than mechanical tests and chemical analysis).
This fourth edition cancels and replaces the third edition (ISO 643:2012), of which it constitutes a minor
revision. A note was added after the first paragraph of 7.1.2.
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 643:2015(E)
Steel — Micrographic determination of the apparent grain
size
1 Scope
This International Standard specifies a micrographic method of determining apparent ferritic or
austenitic grain size in steels. It describes the methods of revealing grain boundaries and of estimating
the mean grain size of specimens with unimodal size distribution. Although grains are three-dimensional
in shape, the metallographic sectioning plane can cut through a grain at any point from a grain corner
to the maximum diameter of the grain, thus, producing a range of apparent grain sizes on the two-
dimensional plane, even in a sample with a perfectly consistent grain size.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 3785, Metallic materials — Designation of test specimen axes in relation to product texture
ASTM E112, Standard Test Methods for Determining Average Grain Size
3 Terms a nd definiti ons
For the purposes of this document, the following terms and definitions apply.
3.1
grain
closed polygonal shape with more or less curved sides, which can be revealed on a flat cross-section
through the sample, polished and prepared for micrographic examination
3.1.1
austenitic grain
crystal with a face-centered cubic crystal structure which may or may not contain annealing twins
3.1.2
ferritic grain
crystal with a body-centered cubic crystal structure which never contains annealing twins
Note 1 to entry: Ferritic grain size is generally estimated for non-alloy steels with a carbon content of 0,25 %
or less. If pearlite islands of identical dimensions to those of the ferrite grains are present, the islands are then
counted as ferrite grains.
3.2
index
positive, zero, or possibly negative number G which is derived from the mean number m of grains counted
in an area of 1 mm of the section of the specimen
Note 1 to entry: By definition, G = 1 where m = 16; the other indices are obtained by the formula
G
m=×82 .
ISO/FDIS 643:2015(E)
3.3
intercept
N
number of grains intercepted by a test line, either straight or curved
Note 1 to entry: See Figure 1.
Note 2 to entry: Straight test lines will normally end within a grain. These end segments are counted as 1/2 an
interception. N is the average of a number of counts of the number of grains intercepted by the test line applied
randomly at various locations. N is divided by the true line length, L , usually measured in millimetres, in order
T
to obtain the number of grains intercepted per unit length, N .
L
3.4
intersection
P
number of intersection points between grain boundaries and a test line, either straight or curved
Note 1 to entry: See Figure 1.
Note 2 to entry: P is the average of a number of counts of the number of grain boundaries intersected by the test
...
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