EN 10247:2007

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Micrographic examination of the non-metallic inclusion content of steels using standard picturesDétermination micrographique de la teneur en inclusions non-métalliques des aciers a l'aide d'images-typesMetallographische Prüfung des Gehaltes nichtmetallischer Einschlüsse in Stählen mit BildreihenTa slovenski standard je istoveten z:EN 10247:2007SIST EN 10247:2007en,fr,de77.040.99Druge metode za preskušanje kovinOther methods of testing of metalsICS:SIST ENV 10247:2000/AC:2001SIST ENV 10247:20001DGRPHãþDSLOVENSKI
STANDARDSIST EN 10247:200701-september-2007

EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 10247April 2007ICS 77.040.99Supersedes ENV 10247:1998
English VersionMicrographic examination of the non-metallic inclusion contentof steels using standard picturesDétermination micrographique de la teneur en inclusionsnon-métalliques des aciers à l'aide d'images-typesMetallographische Prüfung des Gehaltes nichtmetallischerEinschlüsse in Stählen mit BildreihenThis European Standard was approved by CEN on 13 January 2007.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN 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 translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2007 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 10247:2007: E

2 Contents Foreword.5 Introduction.6 1 Scope.7 2 Normative references.7 3 Principles.7 4 Terms and definitions.8 4.1 General.8 4.2 Proximity.9 4.3 Parameters.9 4.4 Classes.10 4.5 Others.10 5 Symbols and abbreviations.11 6 Sampling.13 6.1 General.13 6.2 Minimum reduction.13 6.3 Size and location of test area.13 6.4 Number of specimens.14 6.5 Preparation of specimens.14 7 Test method.14 7.1 Magnification.14 7.2 Field of view.15 7.3 Definition of the pictures of the chart.15 7.3.1 Size and Shape.15 7.3.2 Parameters.15 7.3.3 Arrangement of the pictures.15 7.4 Procedure.15 7.4.1 General.15 7.4.2 Several inclusions of mixed sizes in one field.16 7.4.3 Scanning.16 7.4.4 Assessment and evaluation.16 7.4.5 Evaluation of different types of inclusions.17 7.4.6 Default assumptions.17 7.4.7 Recording of results.17 8 Types of assessment.17 8.1 Worst inclusion method: method P.17 8.1.1 Principle.17 8.1.2 Evaluation of PL (worst length).17 8.1.3 Evaluation of Pd (worst diameter).18 8.1.4 Evaluation of Pa (worst area).18 8.2 Worst field method: method M.18 8.2.1 Principle.18 8.2.2 Evaluation of Mn (rating according to number).18 8.2.3 Evaluation of ML (rating according to length).18 8.2.4 Evaluation of Md (rating according to diameter).18 8.2.5 Evaluation of Ma (rating according to area).18 8.3 Average field method: method K.19

Type of inclusions.34 Annex B (normative)
Parameters and assessments to be used if not otherwise specified.36 Annex C (informative)
Examples for inclusions of different types.37 Annex D (informative)
Shape factor.41 Annex E (informative)
Examples for magnification.42 Annex F (informative)
Details of the eyepiece graticules.44 Annex G (normative)
Manufacturing of eyepiece graticule.45 G.1 General.45 G.2 Narrow field microscopes.45 G.3 Broad field microscopes.46 Annex H (normative)
Calculation basis for the pictures of the chart.49 Annex K (normative)
Rules for classification.51 K.1 Definition of classes.51 K.2 Classification of length.51 K.3 Classification of width.51 K.4 Classification of diameter.51 K.5 Classification of area.52 Annex L (informative)
Comparison of inclusion types in different standards.53 Annex M (informative)
Worst inclusion assessment.54 Annex N (informative)
Worst field assessment.56 N.1 General.56 N.2 Evaluation of Mn.56 N.3 Evaluation of Mn, ML and Md.56 N.4 Evaluation of Mn and Ma.57 Annex P (informative)
Average field assessment.60 P.1 General.60 P.2 Evaluation of Kn, KL and Kd.60 P.3 Evaluation of Kn and Ka.60 P.4 Restricted values.60 Annex Q (normative)
Calculation basis for the assessment.69 Q.1 Worst inclusion assessment.69 Q.2 Worst field assessment.69 Q.2.1 Calculation of Mn.69 Q.2.2 Calculation of ML.69 Q.2.3 Calculation of Md.70 Q.2.4 Calculation of Ma.70 Q.3 Average field.70 Annex R (normative)
Determination of precision and scanning parameters for average field assessment.72 Annex S (informative)
Edge Errors correction.75 S.1 General.75 S.2 Field by field measurement.75 Annex T (normative)
Calculation of average values of parameters for one class.77

4 Annex U (normative)
Average values of parameters.79 Annex V (informative)
Comments of the working group.80 V.1 General.80 V.2 Length.80 V.3 Width.80 V.4 Number.80 V.5 Resolution.80 V.6 Area.81 V.7 Description of inclusions.81 V.8 Globular particles.82 V.9 Shape factor.82 V.10 Combined inclusions.83 V.11 Measuring frame.83 Bibliography.84

6 Introduction This document establishes procedures for the assessment of inclusions in steels, based on their morphology using standard pictures. These procedures include principles that are coherent with physical results obtained from inclusion measurements. The results are in physical units: length in µm/ mm2, number/ mm2, areas in µm2/ mm2. In comparison to other inclusion rating standards, in this standard the order of the classification begins with the length (row index q).These results can be transposed into other standard's ratings for comparison purposes. The conditions of assessments, for instance the rules to scan fields on the specimen, are defined such that there is an optimization between magnification and the number of fields to be assessed. The same precision level is achieved by using the same method in manual evaluation and computer controlled measurements. The chart of standard pictures is derived from mathematical principles. The results and their precision may be directly computed from field assessments.

LLL≤<µm (1)
8 The width wx is classified in column k if: kx1-k
www≤< µm (2) In Figure 5 the first row on the top without number and the first column on the left without number and a thicker surrounding contain the lower limiting pictures. Inclusions with a length shorter than that given in that row or a width smaller than that given in that column are not taken into account for classification. Inclusions classified as columns 6 and 11 are called globular. The parameters measured are number, length, width and area. The results of the evaluations can give expressions of worst inclusion, worst field or an average field value, all of which have physical dimensions. In addition to these values, this method gives an estimation of distribution of the inclusions within the test specimens. The entire chart is mathematically based. It has a limited number of pictures, which limits choice and hence improves reproducibility when used in a manual method. The mathematical basis permits use by manual and image analysis methods providing potential for higher statistical precision. The data produced gives a wide range of features for cleanness definition. The chart employs different shapes and magnifications allowing an application to cleaner steels where shape control is of interest. This European Standard contains several different methods of evaluation. The choice of method shall be defined by the product standard or be agreed between the involved parties. By default, the methods of evaluation used are the worst inclusion and the average field method; parameters are given in Annex B. The methods PL, Pd; Kn, KL and Kn, Kd are proposed as standard methods. 4 Terms and definitions For the purposes of this document, the following terms and definitions apply. 4.1 General 4.1.1 particle single precipitate, in general non-metallic 4.1.2 inclusion general designation of particles in association, defined by the size and proximity of particles. It describes a single, separated particle as well as an arrangement of at least 2 particles (see Figure 2a) if the distance t
is ≤ 10 µm and the distance e is ≤ 40 µm and the main axis of the particles are parallel within ± 10 °. For an arrangement of only two globular particles, each particle shall be considered as an individual inclusion. An inclusion can also be formed by several stringers if the distances t and e are ≤ 10 µm and ≤ 40 µm (see Figure 2b). Particles with L < 3 µm or w < 2 µm are not taken into account (see Figure 2c). Special cases: If elongated and more or less spherical particles are combined, see Figure 2d, in general it is treated as one inclusion. In case 4 the width of the largest particle is consulted for the width of the inclusion. If in this case w1 > 3 w2 then the particles w1 and w2 are treated separately. For an example see Figure 2e. Some examples for inclusions are given in Figure 2f

NOTE For example see Annex C. This is defined in one field of view 4.3 Parameters 4.3.1 length dimension of an inclusion in the main direction of deformation, always assumed to be greater than the width 4.3.2 diameter maximum dimension of inclusion classified according to column 6 (globular inclusion) 4.3.3 width Maximum width perpendicular to the direction of principal deformation. This is the width of the ellipse inscribed to the confining rectangle and having the same length as the inclusion. For manual evaluation this value can only be estimated. The width is the maximum width perpendicular to the direction of principal deformation for inclusions with only one particle. The width w of an inclusion with 2 particles is given by the largest particle (see Figure 2a). Width of a stringer (see Figure 1b): The width of a stringer is defined as the width of an ellipse inscribed to the confining rectangle and having the same length as the stringer Width of an inclusion out of several stringers (see Figure 2b). The distance t between two stringers is defined as the shortest distance between the confining rectangles in a transverse direction. The distance e is defined as the shortest distance between the confining rectangles in a machine direction. Case a) for 0 ≤ e ≤ 40 µm, t ≤ 10 µm: is the width of an inclusion out of two stringers defined as the width of the widest stringer. (wtotal = w1, w1 > w2) (see Figure 2b, a)).

10 Case b) for e < 0 µm, t ≤ 10 µm: is the width of an inclusion out of two stringers defined as the sum of the stringers' widths and the distance t (wtotal = w1 + w2 + t) (see Figure 2b, b). The width of an inclusion, which consists of several stringers, is determined by the width of the widest stringer. This is identified under consideration of the neighboring stringers corresponding to case a) and b), see Figure 2b, c) 4.3.4 area area of the ellipse inscribed to the confining rectangle and having the same length as the inclusion (see 4.3.3 and Figures 1a, 1b) 4.3.5 shape factor exponent f in the equation  cL
=aL2f4 (3) NOTE For details see Annex D 4.4 Classes 4.4.1 elongated particles particles with elliptical shape (see Figure 1a) 4.4.2 globular particles circular or rectangular particles classified as column 6 4.4.3 type types of inclusions are separated according to their colour, shape and arrangement and not by chemical composition (see Annex A).
4.5 Others 4.5.1 lot unit of material processed at one time and subject to similar processing variables 4.5.2 restricted values values of the average field assessment restricted to inclusions greater than a defined length, shape factor or area

5 Symbols and abbreviations Symbol Unit Designation a µm2 area of inclusions b
width of the plate c µm factor, 1 µm d µm diameter of inclusions e µm interparticle distance (elongation axis) f
shape factor b
black coloured g
grey coloured (as sulphides) h
coloured (pink or yellow) (as nitrides) i
inclusion index j
field index k
column number m
type of inclusion index max
index of maximum value of n, L, w, d, a (in j or s) n
number of assessed particles, inclusions ns
number of assessed inclusions per specimen o
black coloured (as oxides) p
particle index q
row number s
specimen index t µm interparticle distance (transverse axis) u µm scale unit in microscope eyepiece v
width of polished surface w µm width of inclusions x
variable av or −
average value of n, L, w, a .

12 .
scattered, elongated inclusion type .g
scattered, elongated, grey coloured inclusion type .b
scattered, elongated, black coloured inclusion type .gb
scattered, elongated, grey / black coloured inclusion type ß
aligned, globular inclusion type ßb
aligned, globular, black coloured inclusion type,
aligned, elongated inclusion type b
aligned, elongated, black coloured inclusion type g
aligned, elongated, grey coloured inclusion type /
scattered, globular inclusion type /b
scattered, globular, black coloured inclusion type /g
scattered, globular grey coloured inclusion type /gb
scattered, globular, grey / black coloured inclusion type A µm2 area of field of view on the specimen B
polished surface D
diameter of product MD
main direction of deformation (e. g. rolling direction) E mm length of test area G
magnification H µm length of measuring frame on the specimen I
length of an stage micrometer K - , µm, µm2/mm2 average field assessment L µm length of inclusions M -, µm, µm2/mm2 worst field assessment Nj
number of fields Ns
number of specimens P
worst inclusion assessment Q
factor for K-assessment R
restricted values
nj, nj
number of inclusions in a field;
jn, jn average number of inclusions per field. 6 Sampling 6.1 General Unless otherwise specified in the technical delivery conditions, the following requirements apply. 6.2 Minimum reduction The shape of the inclusions depends, to a large extent, on the degree of reduction of the steel. The chart can only be used if the shape of inclusions in the specimen can be compared with that given in the pictures of the chart. NOTE It is recommended that products should have a minimum reduction by a factor of five. If the deformation is less than a factor of five, care should be taken to differentiate between porosity and inclusions, both of which may be present. 6.3 Size and location of test area The polished surface of the specimen used to determine the content of inclusions shall be a minimum of 200 mm2 with a minimum length greater than 20 mm and a minimum width greater than 10 mm (e. g. 25 mm × 20 mm). It should be possible within this area to define a rectangular test area of 200 mm2 for evaluation with a length to width ratio of 2 (e. g. 20 mm × 10 mm). The longer side of the test area shall be parallel to the direction of the main deformation (e. g. rolling direction). The sampling and the number of specimens shall be specified in the product standard or shall be subject to agreement between parties. In the absence of an agreement, the sampling procedure shall be as follows, see Figure 3: a) bar or billets with a diameter above 50 mm: the test area shall be located halfway between the outer surface and the centre (see Figure 3a); b) bar with a diameter greater than 25 mm and less than or equal to 50 mm: the surface to be examined consists of half the diametral section (from the center to the edge of the specimen) (see Figure 3b); c) bar with a diameter less than or equal to 25 mm: the surface to be examined consists of the full diametral section of sufficient length to obtain a total surface of 200 mm2 (see Figure 3c); d) plates with a thickness less than 25 mm: the specimen contains the whole thickness (see Figure 3d); e) plates with a thickness between 25 mm and 50 mm: the specimen contains half the thickness, position between surface and centre; f) plates with a thickness greater than 50 mm: the specimen contains one quarter of the thickness. The position is not defined. The positions of the measuring planes for tubes are given in Figure 3e.

14 For thin products one sample could comprise several specimens. In this case the test area is smaller than 200 mm2 per specimen. For any other product, the sampling procedures shall be subject to agreement between parties. 6.4 Number of specimens Single specimens do not provide a representative index of the content of inclusions of a cast or a batch and therefore the test is to be carried out on a number of specimens. If the number of specimens taken is not defined in the product standard or by special agreement, the content of inclusions shall be determined on not less than six specimens. 6.5 Preparation of specimens The specimen shall be cut so as to obtain a surface for examination. In order to achieve a flat surface and to avoid rounding the edges of the specimen when polishing, the specimen may be held mechanically or may be mounted. When polishing specimens, it is important to avoid any tearing out or deformation of the inclusions or contami-nation of the polished surface, so that the surface is as clean as possible and the appearance of the inclusions is not affected. These precautions are of particular importance when the inclusions are small. It is advisable to use diamond paste for polishing. The kind of lubricant can depend on the inclusion type (water may not be an acceptable lubricant for certain types of inclusions, e.g. sulfides). No particles of a grinding or polishing agent shall be pressed into the polished surface. In certain cases it may be necessary for the specimen to be hardened before polishing in order to retain inclusions. 7 Test method 7.1 Magnification The magnification G is defined only by the size of the measuring square frame on the specimen. To use the chart with different magnifications, the length H of the side of the measuring frame on the specimen shall have one of the three following values:
H = 350 µm, H = 710 µm, H = 1 410 µm. These values shall be used with an accuracy of ± 0,02 mm for manual evaluation. The area A of one measuring frame on the specimen is given in Table 1. Table 1 — Area A in function of the measuring frame H A Magnification µm mm2
350 710 1 410 0,13 0,5 2,0 200:1 100:1 50:1 EXAMPLE see Annex E. The length of 710 µm is to be used if nothing else is specified. If it is not possible to use this value, other magnifications can be used and shall be recorded. The magnification shall not be changed during one measurement. NOTE When analysing images the resolution of the picture is higher than the shortest length to be determined. Magnifying hundredfold (lens of size 10), it should be 1 µm / pixel or finer and orientate oneself at the optical resolution of the complete system, which ranges up to 0,3 µm in the ideal case.

16 For this comparison a chart in original size shall be used, not the pictures of Figure 5. The pictures are upper limits of the classes (see clause 3 and Annex K). To make comparison easier, eyepiece graticules may be used (see Figure 4). The scale dimensions are correct only for the magnification for which the eyepiece was designed. In addition to their size, inclusions may be classified by the colour, shape and arrangement (see Annex A). 7.4.2 Several inclusions of mixed sizes in one field 7.4.2.1 General To simplify the manual evaluation where many inclusions occur in one field of view, the following approximations can be employed. 7.4.2.2 Elongated inclusions Length, width or area (indirectly). Up to 3 stretched inclusions; these are evaluated separately. If there are more than three inclusions in one field of view, evaluation shall be carried out in three steps: a) inclusions with a length greater than a quarter of the length of the longest inclusion present are evaluated as individuals according to the chart; b) for the rest of the inclusions, the average length of all inclusions and the average width are estimated. Chart classification (row, column and number) is established using these parameters; c) number of inclusions is recorded for the class defined in
b). This number can be estimated using column 11 (see Figure 5). 7.4.2.3 Globular inclusions If the inclusions are greater or equal to 11 µm, then each shall be evaluated separately. In other cases, evaluation shall be carried out in three steps: a) inclusions with a diameter greater than half the diameter of the largest inclusions in the field are evaluated as individuals according to the chart; b) for the rest of the inclusions the average diameter is estimated and chart classification is carried out by comparison with the pictures of column 6; c) number of inclusions is determined and recorded for that class. This number can be estimated using column 11 (see Figure 5). 7.4.3 Scanning For the worst inclusion assessment and the worst field assessment the whole test area shall be scanned . For the average field assessment there are different methods (see 8.3). 7.4.4 Assessment and evaluation Three types of assessments are defined and used in agreement with the customer or the product standard: a) worst inclusion assessment (see 8.1); b) worst field assessment (see 8.2); c) average field assessment (see 8.3).

N and Annex
P, or derived arrangements adapted to the needs of the laboratory. As a default, heterogeneous inclusions partly or completely encapsulated (type EAD), shall be considered as one particle. The product standard or agreement between the parties shall establish for inclusions with mixed particles such as Figure 2d, example 2, whether the two different types are one particle or two types of particles mixed. Without an agreement, if an inclusion consists of both stretched and globular particles, it shall be analyzed according to the predominant shape. Numbers lower than 10 are exactly quoted with two digits after the comma, all other values are mathematically rounded to integers. 8 Types of assessment 8.1 Worst inclusion method: method P 8.1.1 Principle The whole test area must be scanned field by field. The field size is H
= 710 µm for any case, see clause 7.1. On each test area, for each type of inclusion, only the inclusion having the greatest value of the selected parameter (L, d or a) is evaluated by comparison with the chart and recorded. An inclusion crossing the measuring frame shall be resited by a stage movement to lie within the frame. The result of the evaluation is the average of the individual values of the Ns assessed specimens. The equations for this m
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