ASTM E768-99(2005)
(Practice)Standard Guide for Preparing and Evaluating Specimens for Automatic Inclusion Assessment of Steel
Standard Guide for Preparing and Evaluating Specimens for Automatic Inclusion Assessment of Steel
SIGNIFICANCE AND USE
Inclusion ratings done either manually using Test Methods E 45 or automatically using Practice E 1122 or E 1245 are influenced by the quality of specimen preparation. This guide provides examples of proven specimen preparation methods that retain inclusions in polished steel specimens.
This guide provides a procedure to determine if the prepared specimens are of suitable quality for subsequent rating of inclusions. None of these methods should be construed as defining or establishing specific procedures or limits of acceptability for any steel grade.
SCOPE
1.1 This guide² covers two preparation methods for steel metallographic specimens that will be analyzed for nonmetallic inclusions with automatic image analysis (AIA) equipment. The two methods of preparation are offered as accepted methods used to retain nonmetallic inclusions in steel. This guide does not limit the user to these methods.
1.2 A procedure to test the suitability of the prepared specimen for AIA inclusion work, using differential interference contrast (DIC), is presented.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:E768–99 (Reapproved 2005)
Standard Guide for
Preparing and Evaluating Specimens for Automatic
Inclusion Assessment of Steel
This standard is issued under the fixed designation E768; 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.
1. Scope ADJE0768 Differential Interference Contrast Magnification
2 100X and 500X (6 micrographs)
1.1 This guide covers two preparation methods for steel
metallographicspecimensthatwillbeanalyzedfornonmetallic
3. Terminology
inclusions with automatic image analysis (AIA) equipment.
3.1 Definitions:
The two methods of preparation are offered as accepted
3.1.1 For definitions used in this practice, refer to Termi-
methods used to retain nonmetallic inclusions in steel. This
nology E7.
guide does not limit the user to these methods.
3.1.2 differential interference contrast microscopy—a com-
1.2 A procedure to test the suitability of the prepared
prehensive definition appears in Guide E883, paragraph 11.8.
specimen for AIA inclusion work, using differential interfer-
3.2 Definitions of Terms Specific to This Standard:
ence contrast (DIC), is presented.
3.2.1 rigid grinding disk—a non-fabric support surface,
2. Referenced Documents such as a composite of metal/ceramic or metal/polymer,
charged with an abrasive (usually 6 to 15-µm diamond par-
2.1 ASTM Standards:
ticles), and used as the fine grinding operation in a metallo-
E3 Guide for Preparation of Metallographic Specimens
graphic preparation procedure.
E7 Terminology Relating to Metallography
E45 TestMethodsforDeterminingtheInclusionContentof
4. Significance and Use
Steel
4.1 Inclusion ratings done either manually usingTest Meth-
E883 Guide for Reflected−Light Photomicrography
ods E45 or automatically using Practice E1122 or E1245 are
E1122 Practice for Obtaining JK Inclusion Ratings Using
4 influenced by the quality of specimen preparation. This guide
Automatic Image Analysis
provides examples of proven specimen preparation methods
E1245 Practice for Determining the Inclusion or Second-
that retain inclusions in polished steel specimens.
Phase Constituent Content of Metals by Automatic Image
4.2 This guide provides a procedure to determine if the
Analysis
5 prepared specimens are of suitable quality for subsequent
2.2 ASTM Adjuncts:
rating of inclusions. None of these methods should be con-
strued as defining or establishing specific procedures or limits
ThisguideisunderthejurisdictionofASTMCommitteeE04onMetallography
of acceptability for any steel grade.
and is the direct responsibility of Subcommittee E04.01 on Sampling Specimen
Preparation, and Photography.
5. Preparation Methods
CurrenteditionapprovedMy1,2005.PublishedMay2005.Originallyapproved
in 1999. Last previous edition approved in 2004 as E768–99(2004). DOI: 10.1520/ 5.1 Background:
E0768-99R05.
5.1.1 The inclusions in the plane of polish must be fully
Supporting data have been filed atASTM International Headquarters and may
preserved and clearly visible. Preparation should not produce
be obtained by requesting Research Report RR:E04-1002.
excessive relief around the perimeter of the inclusions that
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
would exaggerate the size and number of inclusions on the
Standards volume information, refer to the standard’s Document Summary page on
plane of polish. In many cases, the preparation of specimens
the ASTM website.
4 for inclusion rating is more readily performed after the
Withdrawn. The last approved version of this historical standard is referenced
on www.astm.org. specimens have been hardened by a suitable heat treatment
Acolored plate, consisting of six micrographs that illustrate the use of DIC in
procedure (austenize, quench to fully martensitic structure,
determining a properly prepared sample (at 100x and 500x), is available from
temper at a relatively low temperature).
ASTM Headquarters. Order Adjuct: ADJE0768.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E768–99 (2005)
5.1.2 Cleanliness is an important consideration in all stages correlation between these two systems and the approximate
of specimen preparation. median particle diameter for a given grit size in micrometres.
5.1.2.1 Heat-treated specimens should be wire brushed or
5.1.6 Most preparation systems apply pressure on the speci-
shot blasted or have the surface ground to remove adherent
mens being processed. The best pressure to be used for each
scale.
preparationstepshouldbedeterminedexperimentally.Conver-
5.1.2.2 After completing the grinding steps and before
sions between applied force and pressure are discussed in the
performing the polishing steps, the specimens and specimen
Appendix X1.
holders must be cleaned to prevent contamination of the next
NOTE 1—Care must be taken to protect the polished specimen surface
preparationstep.Cleaningthespecimensandspecimenholders
from scratches or contaminants when using a specimen leveling device.
between each grinding step can eliminate contamination of
coarse abrasives to the following finer preparation step.
5.2 Silicon Carbide Procedure:
5.1.2.3 After the preparation is complete, swab the surface
5.2.1 A summary of the silicon carbide procedure can be
carefully with cotton and a water/soap solution containing a
found in Table 2.
corrosion inhibitor such as a machine coolant or ethyl alcohol
5.2.2 When using a semi-automatic polishing equipment,
solution to remove any films or other debris that would
grinding and polishing should be performed using approxi-
interfere with the inclusion rating.
mately 18 kPa pressure per specimen. (For a specimen holder
5.1.2.4 It is advisable to perform the inclusion analysis as
containing six 32-mm mounts, a force of approximately 87 N
soonaspossibleafterpreparationtominimizestainingorother
must be applied (see X1.4.2).
problems that can affect the analysis.
5.2.2.1 Low pressures are recommended to ensure the
5.1.3 The two methods that follow have been found to be
retention of an assortment of inclusion types found in a variety
reliableproceduresforretaininginclusionsinsteelandachiev-
of steel grades. The relatively low pressures suggested in this
ing the desired results when evaluated by DIC.There are other
procedurewillnotnecessarilyresultinasatisfactorypolishfor
methods that will result in a quality specimen as revealed by
etching and the further evaluation of the specimen’s general
DIC. Each laboratory should develop preparation procedures
microstructure. The pressures used in the following rigid disk
for their materials so that the prepared surfaces meet the
procedure are more likely to result in a surface more satisfac-
requirements presented in 6 of this guide.
tory for revealing general microstructures.
5.1.4 As described in Prractice E3, the specimens may be
5.2.3 Grind the specimens on ANSI 80 grit (P80 FEPA)
sectioned and mounted to ease handling during preparation. It
silicon carbide paper to ensure all sectioning artifacts and
is advisable to use a mounting medium that is hard enough to
deformation damage have been removed and the entire speci-
preserve edges and maintain flatness.
men surface is co-planar to the grinding surface.
5.1.5 Abrasive grit size designations in this guide are
expressedintheAmericanNationalStandardsInstitute(ANSI)
NOTE 2—If the sectioning method resulted in a smooth face and little
or Coated Abrasives Manufacturers Institute (CAMI) system deformation damage, and if after securing the specimens in a fixture for
polishing,theentiresurfaceofinterestisco-planartothegrindingsurface,
units with the corresponding Federation of EuropeanAbrasive
then finer grit papers, such asANSI 180 to 240 (P180 to P240 FEPA) can
Procedure (FEPA) numbers in parentheses. Table 1 provides a
be used for the initial grinding step.
5.2.3.1 An adequate flow of water should remove all loos-
TABLE 1 Comparison of ANSI (CAMI) versus FEPA versus
ened abrasive and grinding debris from the paper during the
Median Diameter of Grit Size in Micrometers
grinding procedure. The flow of water should ensure the
A B C
ANSI (CAMI) FEPA Approximate Median
specimen is kept cool during grinding.
Diameter
(µm)
5.2.4 Continue grinding through the sequence of silicon
60 P60 250
carbide papers listed in Table 2. It may be necessary to clean
80 P80 180
the samples between every grinding step to prevent contami-
100 P100 150
nation of the next preparation step.
120 P120 125
150 P150 90
5.2.5 After completing the entire grinding operation, clean
180 P180 75
the specimens thoroughly, using ethyl alcohol and cotton, then
220 P220 63
240 P240 58.5
rinse and dry. Ultrasonic cleaning can be used.
P280 52.2
5.2.5.1 Theuseofasoapandwatersolutioninanultrasonic
280 P320 46.2
320 P360 40.5 cleaner can attack non-metallic inclusions in some carbon and
P400 35.0
low alloy steels, leading to an exaggeration in the inclusion’s
360 P500 30.2
apparent size. Adding an inhibitor (such as that used as a
400 P600 25.8
P800 21.8 machining coolant) may reduce this size exaggeration.
500 P1000 18.3
5.2.6 Polishthespecimensusing3-µmdiamondabrasiveon
600 P1200 15.3
a low nap cloth, such as woven wool, for 50 s. Clean and dry
800 P2400 8.4
D
1200 P4000 3.0
the specimens as described in 5.2.5.
A
ANSI - American National Standards Institute
5.2.7 Polish the specimens using a 1-µm diamond abrasive
B
CAMI - Coated Abrasives Manufacturers Institute
C on a high nap cloth for 50 s. Clean and dry the specimens as
FEPA - Federation of European Abrasive Producers
D
Not a FEPA designation described in 5.2.5.
E768–99 (2005)
TABLE 2 Preparation Method I Silicon Carbide Abrasive Paper Grinding
C
Surface Coolent/ Abrasive Size/Type Time Force Surface Relative Rotation
A B
Lubricant ANSI [FEPA] (seconds) newtons [lbs] Speed
RPM
Planar Grinding
D
Paper Water 80 [P80] grit SIC 60 14 [2] 300 Complementary
Fine Grinding
Paper Water 120 [P120] grit SIC 14 [2] 300 Complementary
Paper Water 240 [P240] grit SIC 60 14 [2] 300 Complementary
Paper Water 320 [P50
...
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