ASTM E1245-03(2008)
(Practice)Standard Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis
Standard Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis
SIGNIFICANCE AND USE
This practice is used to assess the indigenous inclusions or second-phase constituents of metals using basic stereological procedures performed by automatic image analyzers.
This practice is not suitable for assessing the exogenous inclusions in steels and other metals. Because of the sporadic, unpredictable nature of the distribution of exogenous inclusions, other methods involving complete inspection, for example, ultrasonics, must be used to locate their presence. The exact nature of the exogenous material can then be determined by sectioning into the suspect region followed by serial, step-wise grinding to expose the exogenous matter for identification and individual measurement. Direct size measurement rather than application of stereological methods is employed.
Because the characteristics of the indigenous inclusion population vary within a given lot of material due to the influence of compositional fluctuations, solidification conditions and processing, the lot must be sampled statistically to assess its inclusion content. The largest lot sampled is the heat lot but smaller lots, for example, the product of an ingot, within the heat may be sampled as a separate lot. The sampling of a given lot must be adequate for the lot size and characteristics.
The practice is suitable for assessment of the indigenous inclusions in any steel (or other metal) product regardless of its size or shape as long as enough different fields can be measured to obtain reasonable statistical confidence in the data. Because the specifics of the manufacture of the product do influence the morphological characteristics of the inclusions, the report should state the relevant manufacturing details, that is, data regarding the deformation history of the product.
To compare the inclusion measurement results from different lots of the same or similar types of steels, or other metals, a standard sampling scheme should be adopted such as described in Practice E 45.
The test measureme...
SCOPE
1.1 This practice describes a procedure for obtaining stereological measurements that describe basic characteristics of the morphology of indigenous inclusions in steels and other metals using automatic image analysis. The practice can be applied to provide such data for any discrete second phase.
Note 1—Stereological measurement methods are used in this practice to assess the average characteristics of inclusions or other second-phase particles on a longitudinal plane-of-polish. This information, by itself, does not produce a three-dimensional description of these constituents in space as deformation processes cause rotation and alignment of these constituents in a preferred manner. Development of such information requires measurements on three orthogonal planes and is beyond the scope of this practice.
1.2 This practice specifically addresses the problem of producing stereological data when the features of the constituents to be measured make attainment of statistically reliable data difficult.
1.3 This practice deals only with the recommended test methods and nothing in it should be construed as defining or establishing limits of acceptability.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: E1245 − 03(Reapproved 2008)
Standard Practice for
Determining the Inclusion or Second-Phase Constituent
Content of Metals by Automatic Image Analysis
This standard is issued under the fixed designation E1245; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Thispracticemaybeusedtoproducestereologicalmeasurementsthatdescribetheamount,number,
size,andspacingoftheindigenousinclusions(sulfidesandoxides)insteels.Themethodmayalsobe
applied to assess inclusions in other metals or to assess any discrete second-phase constituent in any
material.
1. Scope 2. Referenced Documents
1.1 Thispracticedescribesaprocedureforobtainingstereo- 2.1 ASTM Standards:
logical measurements that describe basic characteristics of the E3Guide for Preparation of Metallographic Specimens
morphologyofindigenousinclusionsinsteelsandothermetals E7Terminology Relating to Metallography
using automatic image analysis.The practice can be applied to E45Test Methods for Determining the Inclusion Content of
provide such data for any discrete second phase. Steel
E768Guide for Preparing and Evaluating Specimens for
NOTE 1—Stereological measurement methods are used in this practice
Automatic Inclusion Assessment of Steel
to assess the average characteristics of inclusions or other second-phase
particles on a longitudinal plane-of-polish. This information, by itself,
does not produce a three-dimensional description of these constituents in
3. Terminology
space as deformation processes cause rotation and alignment of these
3.1 Definitions:
constituents in a preferred manner. Development of such information
requiresmeasurementsonthreeorthogonalplanesandisbeyondthescope 3.1.1 For definitions of terms used in this practice, see
of this practice.
Terminology E7.
3.2 Symbols:
1.2 This practice specifically addresses the problem of
producing stereological data when the features of the constitu-
A¯ = the average area of inclusions or particles, µm .
ents to be measured make attainment of statistically reliable
A = the area fraction of the inclusion or constituent.
A
data difficult.
A = the area of the detected feature.
i
1.3 This practice deals only with the recommended test
A = the measurement area (field area, mm ).
T
H = the total projected length in the hot-working
methods and nothing in it should be construed as defining or
T
establishing limits of acceptability. direction of the inclusion or constituent in the
field, µm.
1.4 The values stated in SI units are to be regarded as
L¯ = the average length in the hot-working direction
standard. No other units of measurement are included in this
of the inclusion or constituent, µm.
standard.
L = the true length of scan lines, pixel lines, or grid
T
1.5 This standard does not purport to address all of the
lines (number of lines times the length of the
safety concerns, if any, associated with its use. It is the
lines divided by the magnification), mm.
responsibility of the user of this standard to establish appro-
n = the number of fields measured.
priate safety and health practices and determine the applica-
N = the number of inclusions or constituents of a
A
bility of regulatory limitations prior to use.
given type per unit area, mm .
This practice is under the jurisdiction of ASTM Committee E04 on Metallog-
raphy and is the direct responsibility of Subcommittee E04.14 on Quantitative
Metallography. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2008. Published January 2009. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1988. Last previous edition approved in 2003 as E1245–03. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E1245-03R08. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1245 − 03 (2008)
identification and individual measurement. Direct size mea-
N = the number of inclusions or constituent particles
i
surement rather than application of stereological methods is
or the number of feature interceptions, in the
employed.
field.
N = the number of interceptions of inclusions or
L
5.3 Because the characteristics of the indigenous inclusion
constituentparticlesperunitlength(mm)ofscan
population vary within a given lot of material due to the
lines, pixel lines, or grid lines.
influence of compositional fluctuations, solidification condi-
PP = the number of detected picture points.
i
tions and processing, the lot must be sampled statistically to
PP = the total number of picture points in the field
T
assess its inclusion content. The largest lot sampled is the heat
area.
lotbutsmallerlots,forexample,theproductofaningot,within
s = the standard deviation.
the heat may be sampled as a separate lot. The sampling of a
t = a multiplier related to the number of fields
given lot must be adequate for the lot size and characteristics.
examined and used in conjunction with the
5.4 Thepracticeissuitableforassessmentoftheindigenous
standarddeviationofthemeasurementstodeter-
inclusionsinanysteel(orothermetal)productregardlessofits
mine the 95% CI
sizeorshapeaslongasenoughdifferentfieldscanbemeasured
V = the volume fraction.
V
X¯ = the mean of a measurement. to obtain reasonable statistical confidence in the data. Because
X = an individual measurement. thespecificsofthemanufactureoftheproductdoinfluencethe
i
λ = the mean free path (µm) of the inclusion or
morphological characteristics of the inclusions, the report
constituent type perpendicular to the hot-
should state the relevant manufacturing details, that is, data
working direction.
regarding the deformation history of the product.
∑X = the sum of all of a particular measurement over
5.5 To compare the inclusion measurement results from
n fields.
2 different lots of the same or similar types of steels, or other
∑X = the sum of all of the squares of a particular
metals, a standard sampling scheme should be adopted such as
measurement over n fields.
described in Practice E45.
95% CI = the 95% confidence interval.
% RA = the relative accuracy, %.
5.6 The test measurement procedures are based on the
statisticallyexactmathematicalrelationshipsofstereology for
4. Summary of Practice planar surfaces through a three-dimensional object examined
using reflected light (see Note 1).
4.1 The indigenous inclusions or second-phase constituents
5.7 The orientation of the sectioning plane relative to the
in steels and other metals are viewed with a light microscope
or a scanning electron microscope using a suitably prepared hot-working axis of the product will influence test results. In
general, a longitudinally oriented test specimen surface is
metallographic specimen. The image is detected using a
television-type scanner tube (solid-state or tube camera) and employed in order to assess the degree of elongation of the
malleable (that is, deformable) inclusions.
displayed on a high resolution video monitor. Inclusions are
detected and discriminated based on their gray-level intensity
5.8 Oxide inclusion measurements for cast metals, or for
differences compared to each other and the unetched matrix.
wroughtsectionsthatarenotfullyconsolidated,maybebiased
Measurements are made based on the nature of the discrimi-
by partial or complete detection of fine porosity or micro-
nated picture point elements in the image. These measure-
shrinkage cavities and are not recommended. Sulfides can be
ments are made on each field of view selected. Statistical
discriminated from such voids in most instances and such
evaluation of the measurement data is based on the field-to-
measurements may be performed.
field or feature-to-feature variability of the measurements.
5.9 Results of such measurements may be used to qualify
material for shipment according to agreed upon guidelines
5. Significance and Use
between purchaser and manufacturer, for comparison of differ-
5.1 This practice is used to assess the indigenous inclusions
ent manufacturing processes or process variations, or to pro-
or second-phase constituents of metals using basic stereologi-
vide data for structure-property-behavior studies.
cal procedures performed by automatic image analyzers.
6. Interferences
5.2 This practice is not suitable for assessing the exogenous
6.1 Voids in the metal due to solidification, limited hot
inclusions in steels and other metals. Because of the sporadic,
ductility,orimproperhotworkingpracticesmaybedetectedas
unpredictable nature of the distribution of exogenous
oxides because their gray level range is similar to that of
inclusions, other methods involving complete inspection, for
oxides.
example, ultrasonics, must be used to locate their presence.
The exact nature of the exogenous material can then be
6.2 Exogenous inclusions, if present on the plane-of-polish,
determined by sectioning into the suspect region followed by
will be detected as oxides and will bias the measurements of
serial, step-wise grinding to expose the exogenous matter for
the indigenous oxides. Procedures for handling this situation
are given in 12.5.9.
3 4
Vander Voort, G. F., “Image Analysis,” Vol 10, 9th ed., Metals Handbook: Underwood, E. E., Quantitative Stereology, Addison-Wesley Publishing Co.,
Materials Characterization, ASM, Metals Park, OH, 1986, pp. 309–322. Reading, MA, 1970.
E1245 − 03 (2008)
6.3 Improper polishing techniques that leave excessively are the same as described in Practice E45 (Microscopical
large scratches on the surface, or create voids in or around Methods) or as defined by agreements between manufacturers
inclusions, or remove part or all of the inclusions, or dissolve and users.
water-solubleinclusions,orcreateexcessivereliefwillbiasthe
8.2 Characterization of the inclusions in a given heat lot, or
measurement results.
a subunit of the heat lot, improves as the number of specimens
testedincreases.Testingofbilletsamplesfromtheextremetop
6.4 Dust, pieces of tissue paper, oil or water stains, or other
and bottom of the ingots (after discards are taken) will define
foreign debris on the surface to be examined will bias the
worst conditions of oxides and sulfides. Specimens taken from
measurement results.
interior billet locations will be more representative of the bulk
6.5 If the programming of the movement of the automatic
of the material. Additionally, the inclusion content will vary
stage is improper so that the specimen moves out from under
with the ingot pouring sequence and sampling should test at
theobjectivecausingdetectionofthemountorair(unmounted
least the first, middle and last ingot teemed. The same trends
specimen), measurements will be biased.
are observed in continuously cast steels. Sampling schemes
6.6 Vibrations must be eliminated if they cause motion in must be guided by sound engineering judgment, the specific
processing parameters, and producer-purchaser agreements.
the image.
6.7 Dust in the microscope or camera system may produce
9. Test Specimens
spurious indications that may be detected as inclusions.
9.1 Ingeneral,testspecimenorientationwithinthetestlotis
Consequently, the imaging system must be kept clean.
the same as described in Practice E45 (Microscopical Meth-
ods).Theplane-of-polishshouldbeparalleltothehot-working
7. Apparatus
axis and, most commonly, taken at the quarter-thickness
7.1 A reflected light microscope equipped with bright-field
location. Other test locations may also be sampled, for
objectives of suitable magnifications is used to image the
example, subsurface and center locations, as desired or re-
microstructure. The use of upright-type microscope allows for
quired.
easier stage control when selecting field areas; however, the
9.2 The surface to be polished should be large enough in
specimenswillrequirelevelingwhichcancreateartifacts,such
area to permit measurement of at least 100 fields at the
as scratches, dust remnants and staining, on the polished
necessary magnification. Larger surface areas are beneficial
surface (see 12.2.1). The use of inverted microscopes usually
whenever the product form permits. A minimum polished
result in a more consistent focus between fields, thereby,
surface area of 160 mm is preferred.
requiring less focussing between fields and a more rapid
9.3 Thinproductformscanbesampledbyplacinganumber
completion of the procedure. A scanning electron microscope
of longitudinally oriented pieces in the mount so that the
also may be used to image the structure.
sampling area is sufficient.
7.2 A programmable automatic stage to control movement
9.4 Practice E768 lists two accepted methods for preparing
in the x and y directions without operator attention is recom-
steel samples for the examination of inclusion content using
mended (but not mandatory) to prevent bias in field selection
image analysis. The standard also lists a procedure to test the
and to minimize operator fatigue.
quality of the preparation using differential interference con-
7.3 An automatic focus device may also be employed if
trast (DIC).
found to be reliable. Such devices may be unreliable when
testing steels or metals with very low inclusion contents.
10. Specimen Preparation
10.1 Metallographicspecimenpreparationmustbecarefully
7.4 Anautomaticimageanalyzerwithacameraofadequate
controlled to produce acceptable quality surfaces for image
sensitivity is employed to detect the inclusions, perform
analysis. Guidelines and recommended practices are given in
discrimination, and make measurements.
Methods E3, and Practices E45 and E768.
7.5 A computer is used to store and analyze the measure-
10.2 Thepolishingproceduremustnotalterthetrueappear-
ment data.
ance of the inclusions on the plane-of-polish by producing
7.6 A printer is used to output the data and relevant
excessive relief, pitting, cracking or pullout. Minor fine
identification/background information in a convenient format.
scratches, such as from a 1-µm diamond abrasive, do not
usually interfere with inclusion detection but heavier scratches
7.7 This equipment must be housed in a location relatively
aretobeavoided.Propercleaningofthespecimenisnecessary.
free of airborne dust. High humidity must be avoided as
Use of automatic grinding and polishing devices is recom-
stainingmayoccur;verylowhumiditymustalsobeavoidedas
mended.
static electricity may damage electronic components.
Vibrations, if excessive, must be isolated.
10.3 Establishment of polishing practices should be gui
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:E1245–03 Designation: E 1245 – 03 (Reapproved 2008)
Standard Practice for
Determining the Inclusion or Second-Phase Constituent
Content of Metals by Automatic Image Analysis
This standard is issued under the fixed designation E 1245; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Thispracticemaybeusedtoproducestereologicalmeasurementsthatdescribetheamount,number,
size, and spacing of the indigenous inclusions (sulfides and oxides) in steels. The method may also be
applied to assess inclusions in other metals or to assess any discrete second-phase constituent in any
material.
1. Scope
1.1 This practice describes a procedure for obtaining stereological measurements that describe basic characteristics of the
morphology of indigenous inclusions in steels and other metals using automatic image analysis. The practice can be applied to
provide such data for any discrete second phase.
NOTE 1—Stereologicalmeasurementmethodsareusedinthispracticetoassesstheaveragecharacteristicsofinclusionsorothersecond-phaseparticles
on a longitudinal plane-of-polish. This information, by itself, does not produce a three-dimensional description of these constituents in space as
deformation processes cause rotation and alignment of these constituents in a preferred manner. Development of such information requires measurements
on three orthogonal planes and is beyond the scope of this practice.
1.2 This practice specifically addresses the problem of producing stereological data when the features of the constituents to be
measured make attainment of statistically reliable data difficult.
1.3 Thispracticedealsonlywiththerecommendedtestmethodsandnothinginitshouldbeconstruedasdefiningorestablishing
limits of acceptability.
1.4The measured values are stated in SI units, which are to be regarded as standard. Equivalent inch-pound values are in
parentheses and may be approximate.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
E3 Methods of Preparation of Metallographic Specimens Guide for Preparation of Metallographic Specimens
E7 Terminology Relating to Metallography
E45 Test Methods for Determining the Inclusion Content of Steel
E 768 PracticeGuide for Preparing and Evaluating Specimens for Automatic Inclusion Assessment of Steel
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this practice, see Terminology E 7.
3.2 Symbols:
ThispracticeisunderthejurisdictionofASTMCommitteeE04onMetallographyandisthedirectresponsibilityofSubcommitteeE04.14onQuantitativeMetallography.
Current edition approved Jan. 10, 2003. Published April 2003. Originally approved in 1988. Last previous edition approved in 2000 as E1245–00.
Current edition approved Oct. 1, 2008. Published January 2009. Originally approved in 1988. Last previous edition approved in 2003 as E 1245 – 03.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
, Vol 03.01.volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 1245 – 03 (2008)
¯
A = the average area of inclusions or particles, µm .
A = the area fraction of the inclusion or constituent.
A
A = the area of the detected feature.
i
A = the measurement area (field area, mm ).
T
H = the total projected length in the hot-working direction of the inclusion or constituent in the field, µm.
T
¯
L = the average length in the hot-working direction of the inclusion or constituent, µm.
L = the true length of scan lines, pixel lines, or grid lines (number of lines times the length of the lines divided by the
T
magnification), mm.
n = the number of fields measured.
N = the number of inclusions or constituents of a given type per unit area, mm .
A
N = the number of inclusions or constituent particles or the number of feature interceptions, in the field.
i
N = the number of interceptions of inclusions or constituent particles per unit length (mm) of scan lines, pixel lines, or
L
grid lines.
PP = the number of detected picture points.
i
PP = the total number of picture points in the field area.
T
s = the standard deviation.
t = a multiplier related to the number of fields examined and used in conjunction with the standard deviation of the
measurements to determine the 95 % CI
V = the volume fraction.
V
¯
X = the mean of a measurement.
X = an individual measurement.
i
l = the mean free path (µm) of the inclusion or constituent type perpendicular to the hot-working direction.
(X = the sum of all of a particular measurement over n fields.
(X = the sum of all of the squares of a particular measurement over n fields.
95 % CI = the 95 % confidence interval.
% RA = the relative accuracy, %.
4. Summary of Practice
4.1 The indigenous inclusions or second-phase constituents in steels and other metals are viewed with a light microscope or a
scanning electron microscope using a suitably prepared metallographic specimen. The image is detected using a television-type
scanner tube (solid-state or tube camera) and displayed on a high resolution video monitor. Inclusions are detected and
discriminated based on their gray-level intensity differences compared to each other and the unetched matrix. Measurements are
made based on the nature of the discriminated picture point elements in the image. These measurements are made on each field
of view selected. Statistical evaluation of the measurement data is based on the field-to-field or feature-to-feature variability of the
measurements.
5. Significance and Use
5.1 This practice is used to assess the indigenous inclusions or second-phase constituents of metals using basic stereological
procedures performed by automatic image analyzers.
5.2 This practice is not suitable for assessing the exogenous inclusions in steels and other metals. Because of the sporadic,
unpredictable nature of the distribution of exogenous inclusions, other methods involving complete inspection, for example,
ultrasonics,mustbeusedtolocatetheirpresence.Theexactnatureoftheexogenousmaterialcanthenbedeterminedbysectioning
into the suspect region followed by serial, step-wise grinding to expose the exogenous matter for identification and individual
measurement. Direct size measurement rather than application of stereological methods is employed.
5.3 Because the characteristics of the indigenous inclusion population vary within a given lot of material due to the influence
of compositional fluctuations, solidification conditions and processing, the lot must be sampled statistically to assess its inclusion
content.Thelargestlotsampledistheheatlotbutsmallerlots,forexample,theproductofaningot,withintheheatmaybesampled
as a separate lot. The sampling of a given lot must be adequate for the lot size and characteristics.
5.4 The practice is suitable for assessment of the indigenous inclusions in any steel (or other metal) product regardless of its
size or shape as long as enough different fields can be measured to obtain reasonable statistical confidence in the data. Because
the specifics of the manufacture of the product do influence the morphological characteristics of the inclusions, the report should
state the relevant manufacturing details, that is, data regarding the deformation history of the product.
5.5 To compare the inclusion measurement results from different lots of the same or similar types of steels, or other metals, a
standard sampling scheme should be adopted such as described in Practice E 45.
5.6 The test measurement procedures are based on the statistically exact mathematical relationships of stereology for planar
surfaces through a three-dimensional object examined using reflected light (see Note 1).
Vander Voort, G. F., “Image Analysis,” Vol 10, 9th ed., Metals Handbook: Materials Characterization, ASM, Metals Park, OH, 1986, pp. 309–322.
Underwood, E. E., Quantitative Stereology, Addison-Wesley Publishing Co., Reading, MA, 1970.
E 1245 – 03 (2008)
5.7 The orientation of the sectioning plane relative to the hot-working axis of the product will influence test results. In general,
a longitudinally oriented test specimen surface is employed in order to assess the degree of elongation of the malleable (that is,
deformable) inclusions.
5.8 Oxide inclusion measurements for cast metals, or for wrought sections that are not fully consolidated, may be biased by
partial or complete detection of fine porosity or microshrinkage cavities and are not recommended. Sulfides can be discriminated
from such voids in most instances and such measurements may be performed.
5.9 Results of such measurements may be used to qualify material for shipment according to agreed upon guidelines between
purchaser and manufacturer, for comparison of different manufacturing processes or process variations, or to provide data for
structure-property-behavior studies.
6. Interferences
6.1 Voids in the metal due to solidification, limited hot ductility, or improper hot working practices may be detected as oxides
because their gray level range is similar to that of oxides.
6.2 Exogenous inclusions, if present on the plane-of-polish, will be detected as oxides and will bias the measurements of the
indigenous oxides. Procedures for handling this situation are given in 12.5.9.
6.3 Improper polishing techniques that leave excessively large scratches on the surface, or create voids in or around inclusions,
or remove part or all of the inclusions, or dissolve water-soluble inclusions, or create excessive relief will bias the measurement
results.
6.4 Dust, pieces of tissue paper, oil or water stains, or other foreign debris on the surface to be examined will bias the
measurement results.
6.5 If the programming of the movement of the automatic stage is improper so that the specimen moves out from under the
objective causing detection of the mount or air (unmounted specimen), measurements will be biased.
6.6 Vibrations must be eliminated if they cause motion in the image.
6.7 Dust in the microscope or camera system may produce spurious indications that may be detected as inclusions.
Consequently, the imaging system must be kept clean.
7. Apparatus
7.1 A reflected light microscope equipped with bright-field objectives of suitable magnifications is used to image the
microstructure. The use of upright-type microscope allows for easier stage control when selecting field areas; however, the
specimens will require leveling which can create artifacts, such as scratches, dust remnants and staining, on the polished surface
(see 12.2.1). The use of inverted microscopes usually result in a more consistent focus between fields, thereby, requiring less
focussingbetweenfieldsandamorerapidcompletionoftheprocedure.Ascanningelectronmicroscopealsomaybeusedtoimage
the structure.
7.2 Aprogrammable automatic stage to control movement in the x and y directions without operator attention is recommended
(but not mandatory) to prevent bias in field selection and to minimize operator fatigue.
7.3 Anautomaticfocusdevicemayalsobeemployediffoundtobereliable.Suchdevicesmaybeunreliablewhentestingsteels
or metals with very low inclusion contents.
7.4 An automatic image analyzer with a camera of adequate sensitivity is employed to detect the inclusions, perform
discrimination, and make measurements.
7.5 A computer is used to store and analyze the measurement data.
7.6 A printer is used to output the data and relevant identification/background information in a convenient format.
7.7 This equipment must be housed in a location relatively free of airborne dust. High humidity must be avoided as staining
may occur; very low humidity must also be avoided as static electricity may damage electronic components. Vibrations, if
excessive, must be isolated.
8. Sampling
8.1 In general, sampling procedures for heat lots or for product lots representing material from a portion of a heat lot are the
same as described in Practice E 45 (Microscopical Methods) or as defined by agreements between manufacturers and users.
8.2 Characterizationoftheinclusionsinagivenheatlot,orasubunitoftheheatlot,improvesasthenumberofspecimenstested
increases. Testing of billet samples from the extreme top and bottom of the ingots (after discards are taken) will define worst
conditions of oxides and sulfides. Specimens taken from interior billet locations will be more representative of the bulk of the
material. Additionally, the inclusion content will vary with the ingot pouring sequence and sampling should test at least the first,
middle and last ingot teemed. The same trends are observed in continuously cast steels. Sampling schemes must be guided by
sound engineering judgment, the specific processing parameters, and producer-purchaser agreements.
9. Test Specimens
9.1 In general, test specimen orientation within the test lot is the same as described in Practice E 45 (Microscopical Methods).
The plane-of-polish should be parallel to the hot-working axis and, most commonly, taken at the quarter-thickness location. Other
test locations may also be sampled, for example, subsurface and center locations, as desired or required.
E 1245 – 03 (2008)
9.2 The surface to be polished should be large enough in area to permit measurement of at least 100 fields at the necessary
magnification. Larger surface areas are beneficial whenever the product form permits. A minimum polished surface area of 160
2 2
mm (0.25 in. ) is preferred. is preferred.
9.3 Thin product forms can be sampled by placing a number of longitudinally oriented pieces in the mount so that the sampling
area is sufficient.
9.4 Practice E 768 lists two accepted methods for preparin
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:E1245–00 Designation: E 1245 – 03 (Reapproved 2008)
Standard Practice for
Determining the Inclusion or Second-Phase Constituent
Content of Metals by Automatic Image Analysis
This standard is issued under the fixed designation E1245; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Thispracticemaybeusedtoproducestereologicalmeasurementsthatdescribetheamount,number,
size,andspacingoftheindigenousinclusions(sulfidesandoxides)insteels.Themethodmayalsobe
applied to assess inclusions in other metals or to assess any discrete second-phase constituent in any
material.
1. Scope
1.1 This practice describes a procedure for obtaining stereological measurements that describe basic characteristics of the
morphology of indigenous inclusions in steels and other metals using automatic image analysis. The practice can be applied to
provide such data for any discrete second phase.
NOTE 1—Stereologicalmeasurementmethodsareusedinthispracticetoassesstheaveragecharacteristicsofinclusionsorothersecond-phaseparticles
on a longitudinal plane-of-polish. This information, by itself, does not produce a three-dimensional description of these constituents in space as
deformationprocessescauserotationandalignmentoftheseconstituentsinapreferredmanner.Developmentofsuchinformationrequiresmeasurements
on three orthogonal planes and is beyond the scope of this practice.
1.2 This practice specifically addresses the problem of producing stereological data when the features of the constituents to be
measured make attainment of statistically reliable data difficult.
1.3 Thispracticedealsonlywiththerecommendedtestmethodsandnothinginitshouldbeconstruedasdefiningorestablishing
limits of acceptability.
1.4The measured values are stated in SI units, which are to be regarded as standard. Equivalent inch-pound values are in
parentheses and may be approximate.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
E3 Methods of Preparation of Metallographic Specimens Guide for Preparation of Metallographic Specimens
E7 Terminology Relating to Metallography
E45 Test Methods for Determining the Inclusion Content of Steel
E768 PracticeGuide for Preparing and Evaluating Specimens for Automatic Inclusion Assessment of Steel
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this practice, see Terminology E7.
3.2 Symbols:Symbols: Symbols:
ThispracticeisunderthejurisdictionofASTMCommitteeE04onMetallographyandisthedirectresponsibilityofSubcommitteeE04.14onQuantitativeMetallography.
Current edition approved Oct. 10, 2000. Published March 2001. Originally published as E1245–88. Last previous edition E1245–95.
Current edition approved Oct. 1, 2008. Published January 2009. Originally approved in 1988. Last previous edition approved in 2003 as E1245–03.
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.For Annual Book of ASTM Standards
, Vol 03.01.volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 1245 – 03 (2008)
¯
A = the average area of inclusions or particles, µm .
A = the area fraction of the inclusion or constituent.
A
A = the area of the detected feature.
i
A = the measurement area (field area, mm ).
T
H = the total projected length in the hot-working direction of the inclusion or constituent in the field, µm.
T
¯
L = the average length in the hot-working direction of the inclusion or constituent, µm.
L = the true length of scan lines, pixel lines, or grid lines (number of lines times the length of the lines divided by the
T
magnification), mm.
n = the number of fields measured.
N = the number of inclusions or constituents of a given type per unit area, mm .
A
N = the number of inclusions or constituent particles or the number of feature interceptions, in the field.
i
N = the number of interceptions of inclusions or constituent particles per unit length (mm) of scan lines, pixel lines, or
L
grid lines.
PP = the number of detected picture points.
i
PP = the total number of picture points in the field area.
T
s = the standard deviation.
t = a multiplier related to the number of fields examined and used in conjunction with the standard deviation of the
measurements to determine the 95% CI
V = the volume fraction.
V
¯
X = the mean of a measurement.
X = an individual measurement.
i
l = the mean free path (µm) of the inclusion or constituent type perpendicular to the hot-working direction.
(X = the sum of all of a particular measurement over n fields.
(X = the sum of all of the squares of a particular measurement over n fields.
95% CI = the 95% confidence interval.
% RA = the relative accuracy, %.
4. Summary of Practice
4.1 The indigenous inclusions or second-phase constituents in steels and other metals are viewed with a light microscope or a
scanning electron microscope using a suitably prepared metallographic specimen. The image is detected using a television-type
scanner tube (solid-state or tube camera) and displayed on a high resolution video monitor. Inclusions are detected and
discriminated based on their gray-level intensity differences compared to each other and the unetched matrix. Measurements are
made based on the nature of the discriminated picture point elements in the image. These measurements are made on each field
ofviewselected.Statisticalevaluationofthemeasurementdataisbasedonthefield-to-fieldorfeature-to-featurevariabilityofthe
measurements.
5. Significance and Use
5.1 This practice is used to assess the indigenous inclusions or second-phase constituents of metals using basic stereological
procedures performed by automatic image analyzers.
5.2 This practice is not suitable for assessing the exogenous inclusions in steels and other metals. Because of the sporadic,
unpredictable nature of the distribution of exogenous inclusions, other methods involving complete inspection, for example,
ultrasonics,mustbeusedtolocatetheirpresence.Theexactnatureoftheexogenousmaterialcanthenbedeterminedbysectioning
into the suspect region followed by serial, step-wise grinding to expose the exogenous matter for identification and individual
measurement. Direct size measurement rather than application of stereological methods is employed.
5.3 Because the characteristics of the indigenous inclusion population vary within a given lot of material due to the influence
of compositional fluctuations, solidification conditions and processing, the lot must be sampled statistically to assess its inclusion
content.Thelargestlotsampledistheheatlotbutsmallerlots,forexample,theproductofaningot,withintheheatmaybesampled
as a separate lot. The sampling of a given lot must be adequate for the lot size and characteristics.
5.4 The practice is suitable for assessment of the indigenous inclusions in any steel (or other metal) product regardless of its
size or shape as long as enough different fields can be measured to obtain reasonable statistical confidence in the data. Because
the specifics of the manufacture of the product do influence the morphological characteristics of the inclusions, the report should
state the relevant manufacturing details, that is, data regarding the deformation history of the product.
5.5 To compare the inclusion measurement results from different lots of the same or similar types of steels, or other metals, a
standard sampling scheme should be adopted such as described in Practice E45.
5.6 The test measurement procedures are based on the statistically exact mathematical relationships of stereology for planar
surfaces through a three-dimensional object examined using reflected light (see Note 1).
Vander Voort, G. F., “Image Analysis,” Vol 10, 9th ed., Metals Handbook: Materials Characterization, ASM, Metals Park, OH, 1986, pp. 309–322.
Underwood, E. E., Quantitative Stereology, Addison-Wesley Publishing Co., Reading, MA, 1970.
E 1245 – 03 (2008)
5.7 The orientation of the sectioning plane relative to the hot-working axis of the product will influence test results. In general,
a longitudinally oriented test specimen surface is employed in order to assess the degree of elongation of the malleable (that is,
deformable) inclusions.
5.8 Oxide inclusion measurements for cast metals, or for wrought sections that are not fully consolidated, may be biased by
partial or complete detection of fine porosity or microshrinkage cavities and are not recommended. Sulfides can be discriminated
from such voids in most instances and such measurements may be performed.
5.9 Results of such measurements may be used to qualify material for shipment according to agreed upon guidelines between
purchaser and manufacturer, for comparison of different manufacturing processes or process variations, or to provide data for
structure-property-behavior studies.
6. Interferences
6.1 Voids in the metal due to solidification, limited hot ductility, or improper hot working practices may be detected as oxides
because their gray level range is similar to that of oxides.
6.2 Exogenous inclusions, if present on the plane-of-polish, will be detected as oxides and will bias the measurements of the
indigenous oxides. Procedures for handling this situation are given in 12.5.9.
6.3 Improper polishing techniques that leave excessively large scratches on the surface, or create voids in or around inclusions,
or remove part or all of the inclusions, or dissolve water-soluble inclusions, or create excessive relief will bias the measurement
results.
6.4 Dust, pieces of tissue paper, oil or water stains, or other foreign debris on the surface to be examined will bias the
measurement results.
6.5 If the programming of the movement of the automatic stage is improper so that the specimen moves out from under the
objective causing detection of the mount or air (unmounted specimen), measurements will be biased.
6.6 Vibrations must be eliminated if they cause motion in the image.
6.7 Dust in the microscope or camera system may produce spurious indications that may be detected as inclusions.
Consequently, the imaging system must be kept clean.
7. Apparatus
7.1 A reflected light microscope equipped with bright-field objectives of suitable magnifications is used to image the
microstructure. The use of upright-type microscope allows for easier stage control when selecting field areas; however, the
specimens will require leveling which can create artifacts, such as scratches, dust remnants and staining, on the polished surface
(see 12.2.1). The use of inverted microscopes usually result in a more consistent focus between fields, thereby, requiring less
focussingbetweenfieldsandamorerapidcompletionoftheprocedure.Ascanningelectronmicroscopealsomaybeusedtoimage
the structure.
7.2 Aprogrammable automatic stage to control movement in the x and y directions without operator attention is recommended
(but not mandatory) to prevent bias in field selection and to minimize operator fatigue.
7.3 Anautomaticfocusdevicemayalsobeemployediffoundtobereliable.Suchdevicesmaybeunreliablewhentestingsteels
or metals with very low inclusion contents.
7.4 An automatic image analyzer with a camera of adequate sensitivity is employed to detect the inclusions, perform
discrimination, and make measurements.
7.5 A computer is used to store and analyze the measurement data.
7.6 A printer is used to output the data and relevant identification/background information in a convenient format.
7.7 This equipment must be housed in a location relatively free of airborne dust. High humidity must be avoided as staining
may occur; very low humidity must also be avoided as static electricity may damage electronic components. Vibrations, if
excessive, must be isolated.
8. Sampling
8.1 In general, sampling procedures for heat lots or for product lots representing material from a portion of a heat lot are the
same as described in Practice E45 (Microscopical Methods) or as defined by agreements between manufacturers and users.
8.2 Characterizationoftheinclusionsinagivenheatlot,orasubunitoftheheatlot,improvesasthenumberofspecimenstested
increases. Testing of billet samples from the extreme top and bottom of the ingots (after discards are taken) will define worst
conditions of oxides and sulfides. Specimens taken from interior billet locations will be more representative of the bulk of the
material.Additionally, the inclusion content will vary with the ingot pouring sequence and sampling should test at least the first,
middle and last ingot teemed. The same trends are observed in continuously cast steels. Sampling schemes must be guided by
sound engineering judgment, the specific processing parameters, and producer-purchaser agreements.
9. Test Specimens
9.1 In general, test specimen orientation within the test lot is the same as described in Practice E45 (Microscopical Methods).
The plane-of-polish should be parallel to the hot-working axis and, most commonly, taken at the quarter-thickness location. Other
test locations may also be sampled, for example, subsurface and center locations, as desired or required.
E 1245 – 03 (2008)
9.2 The surface to be polished should be large enough in area to permit measurement of at least 100 fields at the necessary
magnification. Larger surface areas are beneficial whenever the product form permits. A minimum polished surface area of 160
2 2
mm (0.25 in. ) is preferred. is preferred.
9.3 Thinproductformscanbesampledbyplacinganumberoflongitudinallyorientedpiecesinthemountsothatthesampling
area is sufficient.
9.4 Practice E768 lists two accepted methods for preparing steel samples for the examination of inclusion content using image
analysis. The standard also lis
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