ISO/FDIS 4967

ISO/TC 17/SC 7/WG 4
Secretariat: AFNOR
Date: 2025-112026-01-20
Steel — Determination of the non-metallic inclusion content —
Micrographic method
Acier — Détermination de la teneur en inclusions non métalliques — Méthode micrographique
FDIS stage
ISO/DISFDIS 4967(E:2026(en)
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ii
introuvable.
Contents
Foreword . iv
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 3
5 Principle . 5
6 Sampling . 7
7 Preparation of specimens . 16
8 Determination of the content of inclusions . 16
8.1 Method of observation . 16
8.2 Actual examination . 19
9 Expression of results . 21
9.1 General . 21
9.2 Case of method A . 21
9.3 Case of method B . 22
10 Test report . 22
Annex A (normative) ISO chart images for inclusion types A, B, C, D and subgroup DS . 23
Annex B (normative) Examples of assessment of inclusions . 50
Annex C (informative) Examples of assessment of complex inclusions . 57
Annex D (informative) Illustration of the width definitions . 61
Annex E (informative) Assessment result examples and global inclusion content metrics . 65
Annex F (informative) Relationship between indices and inclusion measurements . 80
Bibliography . 86

iii
ISO/DISFDIS 4967(E:2026(en)
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
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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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
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related to conformity assessment, as well as information about ISO's adherence to the World Trade
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This document was prepared by Technical Committee 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 4967:2013), which has been technically revised.
The main changes are as follows:
— — addingadded the mandatory clauses normative references (see 2Clause 2)) and terms and definitions
(see 3Clause 3),), and renumberingrenumbered the subsequent clauses;
— — modifyingmodified the proximity conditions for stringers (allowing for legacy conditions): the new
transverse conditions mirror the conditions used longitudinally and remove ambiguity;
— — changingchanged the width definition (allowing for legacy/alternative definitions): the new definition
avoids the sensitivity to misalignment of the bounding box and the underestimation of the “largest
particle” approach;
— — addingadded further illustrations of width definitions, including the largest particle approach to
inclusions with overlapping particles;
— — clarifyingclarified the treatment of inclusions intersecting the field of view, particularly for long
inclusions (allowing for legacy treatment);
iv
introuvable.
— — clarifyingclarified the treatment of B/C hybrid stringers;
— — modifying Tables 2modified 0 and 03;;
— — addingadded sampling specifications and the possibility to use stacking and/or rectangular fields for
cross-section thicknesses under 0,71 mm;
— — includingincluded the DS subgroup into D thick rating;
— — clarifyingclarified the treatment of DS inclusions in Method B;
— — clarifyingclarified the averaging of cross sections in Method A;
— — modifyingmodified most of the chart diagrams;
— — replacingreplaced the global metrics for Method B (allowing for legacy metrics);
— — addingadded more analysis examples.
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.
v
ISO/DISFDIS 4967(E:2026(en)
Introduction
Every routine inclusion rating by necessity applies the analysis of an incomplete sample to an entire heat. On
the one hand, only a very small fraction of the total material volume is analysed, and on the other hand the
analysis is performed on a two-dimensional section of three-dimensional inclusions. Standards like the
currentthis document cannot eliminate the associated statistical uncertainties but can strive to add as little
uncertainty as possible by defining the process as clearly as possible.
Despite the statistical shortcomings, methods like those described in this document are widely used to assess
the suitability of a steel product for a given use. However, since it is difficult to achieve reproducible results
owing to the distributional randomness of non-metallic inclusions, even with a large number of specimens,
precautions should be taken when using the method.
One way to reduce the scatter inherent to the method is to avoid relying on subjective human judgment. Image
analysis has shown itself to be a useful tool to improve reproducibility— — if the hardware is appropriately
configured and if the rules in the standard are indisputably clear for the software developer. This document
addresses the minimal system requirements for resolution and reduces ambiguity in its rules compared to the
previous revision.
However, it is acknowledged that neither can steel producers and customers can instantly change
specifications, nor can software developers immediately change the rules for evaluation. To allow for an
adaptation period, where methods and definitions have changed, it is permitted to continue to use the
methods and definitions that have been established in the past. This document refers to such methods and
definitions as well as derived interpretations as “legacy.” Because of the ambiguities of previous editions, there
is no one legacy approach, but instead a variety of legacy approaches.
Another clarification relative to the 2013 revision concerns the DS inclusions. There was much ambiguity
surrounding them because they were presented as another type of inclusions. This made it unclear whether
large globular particles were part of the D rating as well, since one important rule of inclusion rating is to rate
every inclusion once and only once. With the redefinition of DS as a subgroup of type D designed for easy
rating and reporting of oversized type D inclusions it is clear that every DS particle is rated in the Dthick rating,
just as every oversized sulfide is rated in the A rating.
thick
Historically, this standardISO 4967 has always shown a significant similarity to the ASTM E 45 standard. With
the revised definitions, particularly those defining proximity limits, there is a greater separation between the
standards, though due to the inherent statistical uncertainties the ratings will correlate in most instances.
However, these increased differences convinced the ISO TC17 SC7 WG4TC 17 SC 7 to continue using the terms
“fine” and “thick” in order to more clearly distinguish ISO 4967 results from ASTM E 45 results.
Revisions always take place on a strict timeline and often the deadline forces the publication of a standard that
is good enough, but not yet perfect. Topics that further revisions couldcan address include the treatment of
particle clusters, easier oversized reporting for Types A to C, and more guidelines on computer-assisted rating.
It is worth remembering that the changes in this inclusion rating method do not change a good steel into a bad
steel, but serve the goal of a clearer, more differentiated description of the steel.
vi
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Final Draft International Standard ISO/FDIS 4967:2025(en)

Steel — Determination of the non-metallic inclusion content —
Micrographic method
1 Scope
This document specifies a micrographic method of determining the non-metallic inclusions in rolled or forged
steel products having a reduction ratio of at least 3 using the images of a standard reference chart or direct
measurement by image analysis technologies.
ThisThe standard reference chart described in this document is not entirely applicable for certain types of
steel (e.g. free cutting steels).
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— — ISO Online browsing platform: available at www.iso.org/obp
— — IEC Electropedia: available at www.electropedia.org
3.1 3.1
particle
single precipitate, in general non-metallic
3.2 3.2
stringer
arrangement of at least 2 particles for type A and C inclusions and 3 particles for type B, aligned in a plane
parallel to the hot working axis and offset by no more than 10 µm, with a separation of no more than 40 µm
between any two nearest neighbour particles
3.3 3.3
inclusion
general designation of a rateable feature composed of at least one particle, defined by the size and proximity
of its constituents
Note 1 to entry: The inclusion can describe a single particle or a single stringer.
3.4 3.4
length
l
dimension of a particle or an inclusion in the main deformation direction, usually larger than the width
ISO/DISFDIS 4967(E:2026(en)
3.5
3.5
width
w
largest local dimension of a particle or an inclusion measured perpendicular to the main deformation direction
(calliper width), as shown in 0Figure 1
Note 1 to entry: The calliper width clarifies an ambiguity in previous editions. A “largest particle” and a “bounding box”
approach were among the most frequent alternatives. Further illustrations are shown in Annex DAnnex D.

Figure 1 — Schematic of particle and inclusion width
3.6 3.6
aspect ratio
ratio of length to width
3.7 3.7
diameter
d
dimension of a globular particle or inclusion in the main deformation direction
introuvable.
3.8 3.8
worst-field rating
rating in which the specimen is rated for each group and subgroup of inclusion by assigning the value for the
highest severity rating observed of that inclusion group and subgroup anywhere on the evaluated area of the
specimen
3.9 3.9
type
categorization of inclusions according to morphology, colour, and proximity
3.10 3.10
class
categorization by width or diameter within types (fine and thick)
3.11 3.11
group
categorization by type and class
3.12 3.12
globular particle
particle with an aspect ratio less than 3
3.13 3.13
elongated particle
particle with an aspect ratio more than or equal to 3
3.14 3.14
hybrid stringer
stringer consisting of both globular and elongated particles
3.15 3.15
reduction ratio
ratio between original and final cross-sectional area after rolling or forging
3.16 3.16
calibration factor
parameter indicating the actual size on the specimen surface corresponding to the pixel length
4 Symbols
The symbols used are given in 0Table 1.
Table 1 — Symbols
Symbols Definitions Values
A Area of an individual inclusion 𝐴
𝜋
A bar above the symbol indicates an average.
= (𝑙×𝑤)(𝑙×𝑤)
Superscripts used: variable index i, “excess”,
variable class
Subscripts used: selected type/class/group, “tot”
(total), S (specimen), “ox” (“oxidic”), “glob”
(globular), fixed index (e. g. “i = 0,5”)
b Length of sample in rolling direction of tube as
shown in 0Figure7
ISO/DISFDIS 4967(E:2026(en)
Symbols Definitions Values
t Wall thickness
C Weighted global severity indices
i
Superscripts used: selected type/class/group,
“tot” (total)
The subscript “i” stands for “inclusion” and is not
the index number.
d Dimension of a globular particle or inclusion in
the main deformation direction
A bar above the symbol indicates an average.
Superscripts used: variable class c, variable
index i
Subscripts used: “min”, “max”, and selected
type/class/group
e Longitudinal distance between particles as
shown in 0Figures 11-12-0
f Inclusion area fractions
Subscripts used: “tot” (total), “ox” (“oxidic”),
“glob” (globular)
f Inclusion number frequency
number
Superscripts used: selected type/class/group
i Index
l Dimension of a particle or an inclusion in the
main deformation direction, usually larger than
the width
A bar above the symbol indicates an average.
Superscripts used: index i
Subscripts used: “min”, “max”
n Number of type D globular oxides per field
A bar above the symbol indicates an average.
Superscripts used: index i
Subscripts used: “min”
N Number of rated fields
r Width of plate as shown in 0Figures 4-6-0
R Relative area fractions
Superscripts used: selected type/class/group or
combination thereof such as “ox” (“oxidic”)
Subscripts used: Ratio expressed, e. g. “B:C”, “f:t”
(fine to thick), “G:nG” (globular to elongated)
s Transverse distance between particles as shown
in 0Figures 11-12-0
S Specimen area
introuvable.
Symbols Definitions Values
w Dimension of a particle or an inclusion
perpendicular to the main deformation direction
A bar above the symbol indicates an average.
Superscripts used: class c, index i
Subscripts used: “min”, “max”, selected
type/class/group
x Inclusion interdistance
Subscripts used: selected type/class/group
Legacy global metrics
Ct Cleanness index (“t” stands for “total”) 𝐶
t
=( 𝑛 ×𝐹)
∑
𝑖 𝑖
𝑖=0
𝐶 =( 𝑛 ×𝐹)
t ∑ 𝑖 𝑖
𝑖=0
×
𝑆 1 000
×
𝑆
𝑖−2,5 𝑖−2,5
F Weighting factor of index i, always rounded to
i
1,5 1,5
𝐹 =10 10
𝑖
one significant digit
𝑖
i Mean index for the entire assessed surface
moy tot
𝑖 = 𝑖
moy moy
𝑁
𝑖
tot
=
𝑁
i Total index for the entire assessed surface 𝑖
tot
tot
= 𝑖×𝑛 𝑖
∑ 𝑖 tot
𝑖=0
= 𝑖×𝑛
∑
𝑖
𝑖=0
ni Total number of fields (A, B, C, and D) and
inclusions (DS) rated as index i
5 Principle
5.1 5.1 The method consists of comparing the observed field to the chart images defined in this
document and taking in consideration separately each group and subgroup of inclusions. In the case of image
analysis, fields will beare rated according to 0, 0Table 2, Table 3,, and the relationships given in
Annex FAnnex F. Automatic image analysis can be used provided that the accuracy of the method has
previously been validated. Digitized images should have a calibration factor of 1 µm/pixel or preferably finer.
5.2 5.2 The chart images correspond to square fields of view, each with an area of 0,50 mm , as
obtained with a longitudinal plane-of-polish and as observed with bright field illumination at 100×.
5.3 5.3 According to the grey level, shape, and distribution of the inclusions, the chart images are
divided into four main types, bearing the reference A, B, C, and D. These four types represent the most
commonly observed inclusion types and morphologies:
— — Type A (“sulfide” type): highly malleable, individual light grey elongated particles with a wide range
of aspect ratios and generally rounded ends;
— — Type BTypeB (“aluminate” type): numerous non deformable, angular, low aspect ratio (<3), black
or bluish particles (at least three) aligned in the deformation direction;
ISO/DISFDIS 4967(E:2026(en)
— — Type CTypeC (“silicate” type): highly malleable, individual black or dark grey elongated particles
with a wide range of aspect ratios (≥ 3) and generally smooth outlines, often with sharp ends;
— — Type D (globular “oxide” type): non deformable, angular or circular, low aspect ratio (< 3), black or
bluish, randomly distributed particles.
NOTE The chemical composition of the inclusions present in a steel sample cannot be determined with the methods
described in this document. The apparent chemical names attributed to the types A, B, C, and D derive from the typical
composition historically found when analysing inclusions of such morphology and colour. The same is true for the non-
traditional inclusion types in the paragraphs that follow.
5.4 5.4 Non-traditional inclusion types may also be rated based on their morphology compared to the
above four types and a statement about their apparent chemical nature. As an example, globular sulfides
would be rated as a D type and denoted with a descriptive subscript (e.g. D ) defined in the test report.
sulf
Examples of subscripts include D (globular calcium sulfides); D (globular rare earth sulfides); and D
cas RES Dup
(globular duplex inclusions, such as calcium sulfide surrounding an aluminate). The treatment of complex
inclusions should be separately agreed between the parties. Examples are given in Annex CAnnex C.
5.5 5.5 Types of precipitate, such as borides, carbides, carbonitrides or nitrides may also be rated
based on their morphology compared to the above four types and a statement about their apparent chemical
nature as described in 5.45.4. Examination at a magnification greater than 100 × may be used to identify the
nature of the non-traditional inclusions before performing the test.
5.6 5.6 The categorization of inclusions into types A, B, C and D is based on their grey level and then,
after forming stringers, on their morphologies. Each of the four types isshall be further categorized into two
classes based on their width or diameter, as specified in Annex Afor, which six images representing
increasing inclusion content are provided in Annex A. The images for indices 3,5 and higher and the limit
values for indices 5,5 and higher are not given in this document. For simplifying the frequent oversized
reporting for Type D inclusions with a diameter > 13 μm an additional subgroup DS is defined. Oversized Type
D inclusions are rated as D and also as DS.
thick
5.7 5.7 The chart images in Annex AAnnex A carry an index number, i, from 0,5 to 3, the numbers
increasing with the inclusion lengths (Types A, B, C) or by the number (Type D) or by the diameter (Subgroup
DS), as defined in 0Table 2,, and categorized by thickness, as defined in 0Table 3. The total length of
inclusions, or number of inclusions, or diameter of the inclusion in each chart image is the lower boundary
value of 0Table 2. For example, the images for A 2 depict inclusions with a morphology in accordance with
type A and with the-total length corresponding to the lower boundary value of i = 2. For indices larger than
3.,0, the rating is performed by comparing measured values with 0Table 2.

Table 2 — Inclusion rating limits
Type Subgroup
Index
A B C DS
D
i
total length total length total length diameter
count number
µm µm µm µm
0,5 ≥ 37 ≥ 17 ≥ 18 ≥ 1 > 13
1,0 ≥ 127 ≥ 77 ≥ 76 ≥ 4 ≥ 19
introuvable.
Type Subgroup
Index
A B C DS
D
i
total length total length total length diameter
count number
µm µm µm µm
1,5 ≥ 261 ≥ 184 ≥ 176 ≥ 9 ≥ 27
2,0 ≥ 436 ≥ 343 ≥ 320 ≥ 16 ≥ 38
2,5 ≥ 649 ≥ 555 ≥ 510 ≥ 25 ≥ 53
3,0 ≥ 898 ≥ 822 ≥ 746 ≥ 36 ≥ 76
3,5 ≥ 1 181 ≥ 1 147 ≥ 1 029 ≥ 49 ≥ 107
4,0 ≥ 1 498 ≥ 1 530 ≥ 1 359 ≥ 64 ≥ 151
4,5 ≥ 1 848 ≥ 1 973 ≥ 1 737 ≥ 81 ≥ 214
5,0 ≥ 2 230 ≥ 2 476 ≥ 2 163 ≥ 100 ≥ 303
(< 2 641) (< 3 042) (< 2 639) (< 121) (< 429)
⁞ ⁞ ⁞ ⁞ ⁞ ⁞
Table 3 — Inclusion width and diameter parameters
Type Fine class Thick class
µm µm µm µm
A (width) ≥ 2 ≤ 4 > 4 ≤ 12
B (width) ≥ 2 ≤ 9 > 9 ≤ 15
C (width) ≥ 2 ≤ 5 > 5 ≤ 12
D (diameter) ≥ 2 ≤ 8 > 8 ≤ 13
NOTE Type D inclusions with a width less than 2 µm are also not included in the inclusion rating.
6 Sampling
6.1 6.1 The shape of the inclusion depends to a large extent on the reduction ratio of the steel;
therefore, comparative measurements should only be carried out on prepared specimens taken from samples
with a similar reduction ratio.
6.2 6.2 Unless something else is defined in the product standard or agreed by the parties involved, the
polished surface of the specimen used to determine the content of inclusions should be about 200 mm .
6.3 6.3 When the cross-section thickness is insufficient to prepare a single specimen of 200 mm , more
than one specimen shall be taken from the same sampling location to conform to 6.26.2. Where reaching
200 mm or more is onerous, the total length of the longitudinal pieces taken from each sampling location
shall not be less than 100 mm. These specimens shall be analysed as one whole specimen.
6.4 6.4 In general, single sections less than 0,71 mm in thickness are not analysed using this document,
since this is restricted by the field side length. However, as part of a mutual agreement, narrower sections may
be assessed by
a) stacking two or more sections together and thereby creating a thicker aggregate section, making sure that
no small gaps or edge artifactsartefacts between the stacked sections are categorised as inclusions
b) using a rectangular field as long as the field area is 0,5 mm², mm , e.g. 1,0×0,5 mm, provided that the
rectangular fits within the visual field of the microscope at the applied magnification.
ISO/DISFDIS 4967(E:2026(en)
6.5 6.5 The method of sampling, including the sampling location and the number of sampling locations,
shall be defined in the product standard or subject to agreement between the parties.
6.6 6.6 In the absence of such specifications, the sampling procedure should be as follows:
— — bar, wire rod, or wire with a diameter less than or equal to 25 mm: the surface to be examined consists
of the full diametral section of length sufficient to obtain a surface conform to 6.26.2 (see 0Figure 2););
— — bar, wire rod, wire, or billet with a diameter greater than 25 mm and less than or equal to 40 mm: the
surface to be examined consists of at least half the diametral section (from the centre to the edge of the
sample) (see 0Figure 3););
— — bar, wire rod, wire, or billet with diameters greater than 40 mm: the surface to be examined consists
of a part of diametral section located halfway between the outer surface and the centre (see 0Figure 4););
— — plate with a thickness less than or equal to 25 mm: the surface to be examined consists of the whole
thickness, and located at the quarter of the width (see 0Figure 5););
— — plate with a thickness greater than 25 mm and less than or equal to 40 mm: the surface to be examined
consists of at least half the thickness from the surface to the centre and is located at the quarter of the
width (see 0Figure 6););
— — plate with a thickness greater than 40 mm: the surface to be examined consists of quarter the thickness
and is located halfway between the outer surface and the middle of the thickness and at the quarter of the
width (see 0Figure 7););
— — tube or pipe with a wall thickness less than or equal to 25 mm: the surface to be examined consists of
the full diametral section of a length sufficient to obtain a sufficient surface, and, for welded products,
located far away from the welding bead (see 0Figure 8););
— — tube or pipe greater than 25 mm: the surface to be examined consists of a part of the diametral section
located halfway between the outer diameter and the inner diameter, and, for welded products, far away
from the welding bead (see 0Figure 9).).
6.7 6.7 The number of samples to be taken is defined in the product standard or by special agreement.
For any other product, the sampling procedures shall be subject to agreement between the parties.
introuvable.
Figure 2 — Sample from bar with a diameter ≤ 25 mm
ISO/DISFDIS 4967(E:2026(en)
Figure 3 — — Sample from bar or billet with a diameter or length of side > 25 mm and ≤ 40 mm
introuvable.
Figure 4 — Sample from bar or billet with a diameter or length of side > 40 mm
ISO/DISFDIS 4967(E:2026(en)
Key
r width
a rolling direction
r width
a rolling direction
Figure 5 — Sample from plate with thickness ≤ 25 mm
introuvable.
Key
r width
a rolling direction
r width
a rolling direction
Figure 6 — Sample from plate with thickness > 25 mm and ≤ 40 mm
ISO/DISFDIS 4967(E:2026(en)
Key
r width
a rolling direction
r width
a rolling direction
Figure 7 — Sample from plate with thickness > 40 mm
introuvable.
Figure 8 — Sample from tube or pipe with a wall thickness ≤ 25 mm
ISO/DISFDIS 4967(E:2026(en)
Key
t wall thickness
t wall thickness
Figure 9 — Sample from tube or pipe with a wall thickness > 25 mm
7 Preparation of specimens
7.1 7.1 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.
7.2 7.2 When polishing specimens, it is important to avoid any tearing out or deformation of the
inclusions, or contamination of the polished surface, so that the surface is as clean as possible, and the shape
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. In certain cases, it can be necessary for the specimen to be
heat treated before polishing in order to give it the maximum possible hardness.
8 Determination of the content of inclusions
8.1 Method of observation
8.1.1 8.1.1 Examination with the microscope may be by one of two methods:
introuvable.
— — by images on the computer screen, ground glass, or other similar device;
— — by observation by means of an eyepiece.
8.1.2 8.1.2 The method of observation chosen shall be maintained throughout the test.
8.1.3 8.1.3 If the image is displayed on a computer screen, ground glass, or other similar device, the
magnification shall be 100 × ± 2 × on the screen. It is recommended to place an overlay (see 0Figure 9)) of a
71 mm ± 1 mm square (0,50 mm true area) over or behind the computer screen, ground glass, or other
projection screen. The image within the 71 mm square is compared to the chart images of the standard chart
as specified in Annex A(see Annex A).
8.1.4 8.1.4 If the inclusions are examined through the microscope eyepieces, insert a reticle with the test
pattern equivalent to the one shown in 0Figure 9 in the microscope at the appropriate location so that the
test grid area is 0,50 mm at the image plane. In some cases, a magnification greater than 100 × may be used,
provided that the same reference field size (0,5 mm ) is applied for the standard images. This approach shall
be recorded in the test report.
NOTE Separating the scale (one eyepiece) from the square and the reference shapes (the other eyepiece) allows for
measuring the length and width of an inclusion by rotating the scale independently and leaving the field reference fixed.
ISO/DISFDIS 4967(E:2026(en)
Figure 10 — Suggested test pattern for grid overlays or reticles
introuvable.
8.2 Actual examination
8.2.1 General
Two methods are defined as described in 8.2.28.2.2 and 8.2.38.2.3. For both methods, if different types of
inclusions or inclusions of the same type but of a different class are observed in the same field, they shall be
assessed separately.
8.2.2 Method A
Method A is a worst-field rating method. The entire polished surface is examined and, for each type and class
of inclusions, a note is made of the index number i of the chart image which corresponds to the worst field
examined.
8.2.3 Method B
8.2.3.1 8.2.3.1 Method B is a field frequency method. The entire polished surface is examined,
and each field of the specimen is compared with the chart images. The index number i of the field which best
corresponds to the field examined for each type and class of inclusions is noted. AnEach inclusion group shall
be assessed separately, as specified in the assessment example in Annex B, B.1of inclusions of a field can be
seen in B.1 of Annex B.
8.2.3.2 8.2.3.2 In order to minimize the cost of examination, it may be agreed upon to make a
partial examination of the specimen by studying a reduced number of fields, distributed in accordance with a
fixed scheme. Both the number of fields examined, and their distribution shall be arranged by prior agreement.
In general, at least 100 fields are examined.
8.2.4 General rules for methods A and B
8.2.4.1 8.2.4.1 Each field observed is compared with the chart images. If a field of inclusions
falls between two chart images, it is rated following the lower image.
NOTE The presence of numerous elongated inclusions oriented in a consistently different direction from the
presumed main deformation direction indicates a need to rotate the sample. The presence of numerous elongated
inclusions oriented in various different directions indicates that the sample is not suitable for the standard.
8.2.4.2 8.2.4.2 Individual inclusions that have a length greater than the field side length
(0,710 mm) or a width or diameter greater than the thick class maximum (see 0Table 3)) will be rated as
oversized by length, width, or diameter. The oversized dimensions of the inclusion shall be noted separately.
However, the total length of these inclusions shall be included in the overall rating of that field. An as specified
in the assessment example of oversized inclusions in Annex B, B.2can be seen in B.2 of Annex B. .
Legacy processes of dealing with inclusions longer than the field side length are permitted but shall be
declared in the report.
NOTE Custom methods of rating the severity of the oversized inclusions A, B, and C are a matter of agreement
between the parties.
8.2.4.3 8.2.4.3 Any inclusion intersecting the edge of the field of view shall be assigned to a
field of view if the centre of gravity of the inclusion lies within the field for Method A. For Method B, it shall be
assigned to a single field using a process that assigns all inclusions to exactly one field (e.g. centre of gravity,
first found).
Legacy processes of assigning inclusions to fields are permitted but shall be declared in the report.
8.2.4.4 8.2.4.4 All oversized type D inclusions shall be rated as D thick and shall also be rated
as subgroup DS inclusions. For Method A, the DS rating of a specimen is the DS rating of the largest oversized
type D inclusion. For Method B, all the oversized type D inclusions shall be individually tallied and rated,
ISO/DISFDIS 4967(E:2026(en)
regardless of the proximity of other DS inclusions. An assessment example of oversized inclusions can be seen
in B.3B.3 of Annex BAnnex B.
8.2.4.5 8.2.4.5 The reproducibility of measurements is improved if actual measurements
(inclusion lengths of A, B or C types, diameter of DS subgroup) and counts (D types) are made. Use a grid
overlay or reticle, as shown in 0Figure 10,, the measurement limits in 0Tables 2 and 03,, and the
morphological descriptions in 5Clause 5,, as illustrated in the chart.
8.2.4.6 8.2.4.6 Non-traditional inclusion types are rated according to the chart type and
subgroup (A, B, C, D, DS) that best corresponds to their morphology. Compare the length, number, thickness,
or diameter of the inclusions to each type shown in Annex AAnnex A or determine their total length, number,
thickness, or diameter, and use 0Tables 2 and 03 to assign the appropriate index and class. Where necessary,
a higher magnification is used to better discern the individual constituents of complex inclusions. An
assessment example of complex inclusions can be seen in Annex CAnnex C.
8.2.4.7 8.2.4.7 Stringers are formed from single particles of the same grey level category that
meet the following conditions. For type A and C inclusions, two individual particles of lengths l and l are
1 2
considered as one inclusion or stringer if the longitudinal distance e is lower than or equal to 40 μm and if the
distance s (the distance between facing tangent lines of particles) is lower than or equal to 10 μm (see
0Figure 11 and 0F.3).). For type B inclusions, three individual particles of lengths l1, l2 and l3 are considered
as one inclusion or stringer if the longitudinal distance e is lower than or equal to 40 μm and if the distance s,
(the distance between facing tangent lines of particles) is lower than or equal to 10 μm (see 0Figure 12 and
0F.3).). The distance between centreline and centreline of particles is allowed to be used as a legacy definition.
It will gradually be phased out in future revisions. The use of legacy definitions shall be noted in the report.
Deleted Cells
s ≤ 10 µm, 0 ≤ e ≤ 40 µm
s ≤ 10 µm,  0 ≤ e ≤ 40 µm
Figure 11 — Stringer for type A Figure 12 — Stringer for type B inclusions
and C inclusions
8.2.4.8
introuvable.
8.2.4.8 Figure 11 — Stringer for type A and C inclusions

s ≤ 10 µm, 0 ≤ e ≤ 40 µm
Figure 12 — Stringer for type B inclusions
8.2.4.98.2.4.8 In the case of an inclusion with particles of different width, the width to be considered is the
calliper width of the inclusion (see 0Figures 11 and 012)) unless the largest particle width or a legacy
definition is agreed on between the parties.
8.2.4.108.2.4.9 8.2.4.9 Hybrid stringers composed of both globular and elongated black
“oxide” particles are classified as type B or type C. If the number of particles with l/w < 3 is less than 3, the
inclusion is categorized as type C. If the number of particles with l/w < 3 is three or larger, the inclusion is
categorized as type B if the total length of all individual particles with l/w ≥ 3 constitutes less than 50% of the
total inclusion length; otherwise, the inclusion is categorized as type C.
NOTE 0Figure C.2 of Annex CAnnex C shows examples of how to categorize hybrid stringers when specific
information on the chemistry is available.
9 Expression of results
9.1 General
Unless otherwise stated in the product standard or agreement in parties, the results may be expressed as
described in 9.29.2 and 9.39.3 depending on the method used (method A or method B). Any subscripts used
to identify non-traditional inclusion types shall be defined.
9.2 Case of method A
9.2.1 9.2.1 For each specimen and each type and class of inclusions (see Annex BAnnex B),), the index i of
the worst field shall be reported, with the presence of an oversized inclusion being indicated by the letter s.
The dimension of the largest oversized inclusion shall be noted as well. For a single specimen, the notation
may be made using an “e” to indicate the rating for the “thick” class. The specimen 1 in 0Table E.1 would be
noted A 2,0 / Ae 1,0 / B 2,0 / D 1,5 / Des 0,5 / DS 1,0.
9.2.2 9.2.2 On the basis of the index numbers relating to each specimen, an arithmetic mean may be
assessed per cast for each type and class. A typical result is given in E.1E.1 of Annex EAnnex E.
ISO/DISFDIS 4967(E:2026(en)
9.2.3 9.2.3 If fewer than three specimens per cast are rated, or if the surveyed area differs significantly
between specimens, the individual specimen ratings should be reported.
9.3 Case of method B
9.3.1 9.3.1 The number of fields corresponding to each index i, per specimen and per group and subgroup,
shall be reported along with the total number of fields observed (N). It is recommended to formulate
acceptance criteria for Method B as the maximum number of fields of a certain group per inspected area.
9.3.2 9.3.2 The set of results from 9.3.1 9.3.1 may be used in special treatments for expressing results as
global metrics, subject to agreement between the parties. Calculations and typical results are given in
Annex EAnnex E.
10 Test report
The test report shall contain the following information, if available and applicable:
a) a) a dated reference to this document and the method used, e.g. ISO 4967:20YY2026 Method A;
b) b) the use of legacy approaches or alternative definitions for
1) width,
2) proximity conditions,
3) oversized inclusion length,
4) assignation to field of view, and
5) global metrics;
c) c) the steel grade and the cast number;
d) d) the nature (sheet, wire, rod, etc.) and dimensions of the product;
e) e) the relevant sampling information;
f) f) the magnification if greater than 100 ×, or the calibration factor for digital assessments;
g) g) the number of observed fields or the total area examined;
h) h) the results of the examination (including the number, size and type of oversized inclusions or
stringers);
i) i) statement of subscripts used to define any non-traditional inclusion type;
j) j) unique report identification;
k) k) name of operator or unique operato
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