ASTM E2142-01
(Test Method)Standard Test Methods for Rating and Classifying Inclusions in Steel Using the Scanning Electron Microscope
Standard Test Methods for Rating and Classifying Inclusions in Steel Using the Scanning Electron Microscope
SCOPE
1.1 This test method covers procedures to obtain particle size distribution, chemical classification, and E45 ratings of inclusions in steels using an automated scanning electron microscope (SEM) with X-ray analysis and automatic image analysis capabilities.
1.2 There are three discrete methods described. Method 1 is the SEM analog of E1122, which uses image analysis and light microscopy to produce automated E45 ratings. Method 2 produces similar ratings based predominantly on sorting inclusions by chemistry into the traditional classes defined in E45. Method 3 is recommended when explicit detail is needed on particular inclusion types, not necessarily defined in E 45, such as to verify the composition of inclusions in inclusion-engineered steel. Method 3 reports stereological parameters such as volume or number fraction, rather than E45 type ratings.
1.3 This test method deals only with the recommended test methods and nothing in it should be construed as defining or establishing limits of acceptability for any grade of steel or other alloy where the method is appropriate.
1.4 The values stated in SI units are to be regarded as the standard. Values in parentheses are conversions and are approximate, and for information only.
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.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E 2142 – 01
Standard Test Methods for
Rating and Classifying Inclusions in Steel Using the
Scanning Electron Microscope
This standard is issued under the fixed designation E 2142; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope E 766 Practice for Calibrating the Magnification of a Scan-
ning Electron Microscope
1.1 This test method covers procedures to obtain particle
E 768 Practice for Preparing and Evaluating Specimens for
size distribution, chemical classification, and E 45 ratings of
Automated Inclusion Analysis of Steel
inclusions in steels using an automated scanning electron
E 1122 Practice for Obtaining Inclusion Ratings Using
microscope (SEM) with X-ray analysis and automatic image
Automatic Image Analysis
analysis capabilities.
E 1245 Practice for Determining the Inclusion or Second-
1.2 There are three discrete methods described. Method 1 is
Phase Constituent Content of Metals by Automatic Image
theSEManalogofE 1122,whichusesimageanalysisandlight
Analysis
microscopy to produce automated E 45 ratings. Method 2
E 1508 Guide for Quantitative Analysis by Energy Disper-
produces similar ratings based predominantly on sorting inclu-
sive Analysis
sions by chemistry into the traditional classes defined in E 45.
2.2 Adjuncts:
Method 3 is recommended when explicit detail is needed on
ANSI/IEEE STD 759 IEEE Standard Test Procedure for
particular inclusion types, not necessarily defined in E 45, such
Semiconductor X-Ray Energy Spectrometers
as to verify the composition of inclusions in inclusion-
engineered steel. Method 3 reports stereological parameters
3. Terminology
such as volume or number fraction, rather than E 45 type
3.1 Definitions—For definitions of terms used in this test
ratings.
method, see Terminology E 7.
1.3 This test method deals only with the recommended test
3.2 Definitions of Terms Specific to This Standard:
methods and nothing in it should be construed as defining or
3.2.1 Analysis Rules—
establishing limits of acceptability for any grade of steel or
3.2.1.1 acquisition analysis rules—include the criteria to
other alloy where the method is appropriate.
terminate X-ray collection (counts or time, or both), the list of
1.4 The values stated in SI units are to be regarded as the
elements to be analyzed, the number of fields or particles to be
standard. Values in parentheses are conversions and are ap-
analyzed, morphologies of particles from which spectra will be
proximate, and for information only.
collected, etc. (seeAppendix X1 for a more complete listing of
1.5 This standard does not purport to address all of the
typical Acquisition Rules).
safety concerns, if any, associated with its use. It is the
3.2.1.2 post-acquisition analysis rules—define ratios of
responsibility of the user of this standard to establish appro-
X-rayintensitiesorelementalcompositionsrequiredtoidentify
priate safety and health practices and determine the applica-
aninclusionasbelongingtoaparticularchemicalclassification
bility of regulatory limitations prior to use.
and, for Methods 1 and 2 herein, define the main inclusion
2. Referenced Documents class (A, B, or C) to which each chemical classification
belongs.
2.1 ASTM Standards:
3.2.2 chemical classification—defined compositional cat-
E3 Practice for Preparation of Metallographic Specimens
egoriesinwhichinclusionsareplacedaccordingtotheanalysis
E 7 Terminology Relating to Metallography
rules. Categories may be broad (e.g., sulfide, aluminate,
E45 Test Methods for Determining the Inclusion Content
silicate) or more precise (e.g., calcium sulfide, calcium silicate,
of Steel
anorthite, etc.).
These test methods are under the jurisdiction of ASTM Committee E04 on
Metallography and are the direct responsibility of Subcommittee E04.11 on X-Ray
and Electron Metallogrpahy jointly with E04.09 on Steel Inclusions.
Current edition approved April 10, 2001. Published June 2001. This standard is available from The Institute of Electrical and Electronics
Annual Book of ASTM Standards, Vol 03.01. Engineers, Inc., 345 East 47th Street, New York, NY 10017.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E2142–01
3.2.3 critical aspect ratio—the aspect ratio of a single are non-deformable oxides (typically alumina), and Type C
inclusion that defines the boundary between “globular” and inclusions are deformable oxides (typically silicates). Each
“elongated”. defined chemical class is assigned to one of these categories.
3.2.4 discontinuous stringer—two or more Type C or three Once classifications are made based on chemistry, the globular
or moreType B inclusions aligned in a plane parallel to the hot particles from each classification, or from designated classifi-
workingaxisandoffsetfromthestringercenterlinebynomore cations, can be re-classified as Type D inclusions. With regard
than 15 µm (.0006 in), with a separation of < 40 µm (.0016 in.) to morphology, Method 2 differs from Method 1 in that uses a
between any two nearest neighbor inclusions. critical AR of 3 rather than 5. E 45-equivalent ratings are
3.2.5 stringer—an individual oxide inclusion that is highly determined and recorded, and reported particles are usually
elongated in the deformation direction; or two or moreType C, limited to those$ 2 µm in size (see 12.7.1).
or three or more Type B, inclusions aligned in a plane parallel 4.3.3 Method 3 allows inclusions to be analyzed and re-
to the hot working axis and offset (from the stringer centerline) ported in a manner individualized to the material and applica-
by no more than 15 µm (.0006 in.), with a separation of < 40 tion of interest. It allows complete freedom in formulating
µm (.0016 in.) between any two nearest neighbor inclusions. chemical classes.Aspect ratio definitions can be chosen appro-
priately for the application. Termination of the analysis can be
4. Summary of Test Method
based on detecting a certain number of inclusions rather than
4.1 A properly prepared as-polished metallographic speci-
sample area. Size and morphology distributions of all inclu-
men is mounted in a computer-controlled SEM equipped with
sions by chemical class are determined. Indirect terminology
image analysis and X-ray analysis subsystems such that
such as “Type A, B, C and D” and “thin” and “heavy” is not
inclusions intersecting the plane of polish can be imaged and
used; rather, inclusions are classified directly by chemical class
analyzed.
and size range of interest. Particles may be further subdivided
4.2 During analysis, an inclusion is detected by its gray
by morphology. Method 3, as in Practice E 1245, reports basic
level in the back-scattered electron signal. Once detected, size
stereological parameters, such as volume and number fractions
parameters of the inclusion are automatically determined and
of inclusions within each field, as well the maximum Feret’s
its X-ray spectrum collected. Particle morphology, chemistry,
diameter for each inclusion. This method would be used for
and location are stored in the computer, allowing re-
custom analyses, such to report all non-sulfide particles by
examination of the data or the particle itself. In this manner, a
thickness, as may be useful in tire cord applications.
complete or partial size distribution of inclusions by chemical
5. Significance and Use
class can be determined.
4.3 There are three methods described (see Fig. 1): 5.1 This test method is established to cover automated
4.3.1 Method 1 is most similar to Practice E 1122 which SEM/EDX-based procedures for:
useslightmicroscopy,andisintendedtobeitsSEManalog.As 5.1.1 Rating the inclusion content of steels based on proce-
such, it uses morphology as the primary basis for sorting dures listed in Standards E45, E 1122 and E 1245, with the
particles into classes. As in E 1122, a critical aspect ratio of 5 significant difference that the composition of the individual
is defined. Chemistry is used to identify sulfide inclusions and inclusions, as determined by X-ray analysis, is utilized to sort
to discriminate among sulfides when more than one type is them into chemical classes.
present, as well as to ensure that exogenous inclusions and 5.1.2 Determining the number, size and morphological dis-
surface scratches and debris are not included in the ratings. tribution of inclusions in steels sorted by chemical class.
Inclusions will be classified into four categories,TypesA, B, C 5.2 Methods 1 and 2 of this test method are primarily
and D as described in StandardsE45 and E 1122. Elongated intended for rating the inclusion content of steels deoxidized
sulfides are Type A. Other inclusions are oxides and are with silicon or aluminum, both silicon and aluminum, or
classified as Types B, C or D, depending on their morphology, vacuum-treated steels without either silicon or aluminum
as follows: discontinuous stringers of three or more inclusions additions. Guidelines are provided to rate inclusions in steel
with member particles having low aspect ratio are Type B; treatedwithrareearthadditionsorcalcium-bearingcompounds
discontinuousstringersoftwoormoreinclusionswithmember (sections 12.8 and 13.4). When such steels are evaluated, the
particles having high aspect ratio and single elongated oxide test report should describe the nature of the inclusions rated
inclusions are Type C; remaining isolated inclusions are Type according to each inclusion category (A, B, C, D).
D.The categories will be further subdivided as thin, heavy and 5.3 Methods 1 and 2 will provide a quantitative rating of the
oversized, according to their width (as described in 12.7 and inclusion content in half-severity number increments from 0 to
tabulated in Table 1). E 45-equivalent ratings are determined 5 for each inclusion type and thickness (Method D of Test
andrecorded,andreportedparticlesareusuallylimitedtothose MethodE45), as described in 12.10 and in tabulated in Table
$ 2 µm in size (see 12.7.1). 2. E45 ratings by SEM may differ from those determined
4.3.2 The inclusion classification strategy in Method 2 is following E 1122 because of the use of chemistry in the
based predominantly on chemistry, but uses morphology when classifications, and, in the case of Method 2, because of the use
necessary, such as to classify Type D (globular) inclusions and of a smaller critical AR (see 11.14). In order to differentiate
tocomputeseverityratingsforTypeBandCinclusions(which E45 ratings obtained using the SEM from traditional ratings
require determination of stringer lengths). Method 2 is based using light microscopy, the ratings obtained using Method 1 or
on the underlying intention of Test MethodE45, namely, that 2 of this Test Method shall be identified as E 45-SEM1 and
Type A inclusions are deformable sulfides, Type B inclusions E 45-SEM2, respectively.
E2142–01
FIG. 1 Illustration of Classification Methods
E2142–01
TABLE 1 Inclusion Width Parameters
Thin Heavy Oversize
Inclusion Minimum Maximum Minimum Maximum Minimum
Type Width (µm) Width (µm) Width (µm) Width (µm) Width (µm)
A $2 4 >4 12 >12
B $2 9 >9 15 >15
C $2 5 >5 12 >12
D $2 8 >8 13 >13
TABLE 2 Minimum Values for Inclusion Severity Rating Levels
6.1.4 Backscattered Electron Detector and electronics with
for Measurements in Micrometers (For expression in other units,
ability to set one or more thresholds to enable discrimination
see E 1122,Table2)
between inclusions and matrix.
Test MethodE45 Rating Limits (µm at 13 or count)
6.1.5 Control and Image Collection Software to control the
Severity A B C D
beam and stage and to collect images and spectra according to
0.5 37.0 17.2 17.8 1
user-specified parameters.
1.0 127.0 76.8 75.6 2
6.2 Automated Feature-Analysis Software, capable of:
1.5 261.0 184.2 176.0 4
6.2.1 Allowing analysis rules to be set such that chemical
2.0 436.1 342.7 320.5 9
2.5 649.0 554.7 510.3 16
classifications can be made and features sorted according to
3.0 898.0 822.2 746.1 25
chemistry as well as size and morphology.
3.5 1181.0 1147.0 1029.0 36
6.2.2 Distinguishing between elongated and globular par-
4.0 1498.0 1530.0 1359.0 49
4.5 1898.0 1973.0 1737.0 81
ticles based on aspect ratio.
5.0 2230.0 2476.0 2163.0 100
6.2.3 Separating the stringered oxides according to the
difference in morphology (Type B or C) and measuring the
stringer lengths per field of each type.
5.4 Method 3 defines procedures to analyze and report
6.2.4 Connecting stringers which cross field boundaries.
inclusions by arbitrary size distribution and chemical classifi-
6.2.5 Generating standardized reports.
cations. It may be made applicable to any material by appro-
6.3 Special Considerations—The environment housing the
priate choice of these classifications.
equipment must be controlled. Computer equipment, SEMs
5.4.1 Method3determinesandreportsbasic(asusedinTest
and EDX systems all require control of temperature and
Method E 1245) stereological measurements (for example,
humidity and the air must be relatively dust free.
volume fraction of sulfides and oxides, the number of sulfides
oroxidespersquaremillimeter,andsoforth).Thistestmethod,
7. Sampling
however, does not address the measurement of such param-
7.1 Sampling is done in accordance with the guidelines
eters.E45 ratings are not produced in Method 3 because the
given in Test MethodE45.
inclusion classifications do not follow those defined in Test
MethodE45 and Practice E 1122.
8. Test Specimens
5.5 The quantitative results are intended to provide a de-
8.1 The location and orientation of test specimens shall be
scription of the types and amounts of inclusions in a heat of
as described in Test Method E45. In all cases, the polished
steel. This test method contains no guidelines for such use.
surface shall be parallel to the hot-working axis. Studies have
6. Apparatus
demonstrated that inclusion length measurements are signifi-
cantly affected if the plane of polish is angled more than 6
6.1 An automated computer-controlled Scanning Electron
degrees from the longitudinal hot-working direction. Test
Microscope equipped with the following accessories:
specimens should not be cut from areas influenced by shearing
6.1.1 Digital Imaging hardware and software.
which alters the true orientation of the inclusions.
6.1.2 Computer-Controlled Motorized X-Y Stage. It is con-
8.2 The surface to be polished must be at least 160
ceivable that the method described in this standard may be
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.