ASTM B930-03(2012)
(Test Method)Standard Test Method for Rating Grain Size and Frequency of Abnormally Large Grains in Cemented Tungsten Carbides (Hardmetals)
Standard Test Method for Rating Grain Size and Frequency of Abnormally Large Grains in Cemented Tungsten Carbides (Hardmetals)
SIGNIFICANCE AND USE
5.1 The microstructure and grain growth of cemented tungsten carbides affect the material's mechanical and physical properties. The grain size and distribution will affect the material's wear resistance and fracture toughness. Abnormally large grains as compared to the background may introduce an area of weakness in a sintered part.
5.2 This test method may be used in acceptance testing of cemented tungsten carbide materials or the tungsten carbide powder used in their manufacture. The specified grain size used for the E-Rating is to be agreed upon between purchaser and supplier.
SCOPE
1.1 This test method describes a procedure for measuring abnormally large grains and the frequency of those grains in cemented tungsten carbides (hardmetals).
1.2 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
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Standards Content (Sample)
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Designation: B930 − 03 (Reapproved 2012)
Standard Test Method for
Rating Grain Size and Frequency of Abnormally Large
Grains in Cemented Tungsten Carbides (Hardmetals)
This standard is issued under the fixed designation B930; 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.
1. Scope metallograph. Abnormally large grains, compared to the finer-
grained background material, are identified. These grains are
1.1 This test method describes a procedure for measuring
categorized as: ( 1) The number of grains larger than a
abnormally large grains and the frequency of those grains in
specified size, or ( 2) The largest grain observed, or both.
cemented tungsten carbides (hardmetals).
1.2 This standard does not purport to address all of the
5. Significance and Use
safety concerns, if any, associated with its use. It is the
5.1 The microstructure and grain growth of cemented tung-
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- sten carbides affect the material’s mechanical and physical
properties. The grain size and distribution will affect the
bility of regulatory limitations prior to use.
material’s wear resistance and fracture toughness.Abnormally
2. Referenced Documents
large grains as compared to the background may introduce an
area of weakness in a sintered part.
2.1 ASTM Standards:
B243 Terminology of Powder Metallurgy
5.2 This test method may be used in acceptance testing of
B406 Test Method for Transverse Rupture Strength of Ce-
cemented tungsten carbide materials or the tungsten carbide
mented Carbides
powderusedintheirmanufacture.Thespecifiedgrainsizeused
B657 GuideforMetallographicIdentificationofMicrostruc-
for the E-Rating is to be agreed upon between purchaser and
ture in Cemented Carbides
supplier.
B665 Guide for Metallographic Sample Preparation of Ce-
mented Tungsten Carbides
6. Apparatus
3. Terminology
6.1 Metallographic Microscope, capable of magnifications
of up to 1500×.
3.1 Definitions—Definitions of powder metallurgy terms
can be found in Terminology B243.
6.2 Ordinary metallurgical laboratory equipment.
3.2 Definitions of Terms Specific to This Standard:
6.3 Equipment for specimen preparation as outlined in
3.2.1 E-Rating—the number/cm of grains larger than a
Guide B665.
specified size in a fully-etched specimen.
3.2.2 L-Rating—the size, in µm, of the largest grain ob-
7. Test Specimens
served in a fully-etched specimen.
7.1 Specimen Size—The recommended specimen shall be
4. Summary of Test Method
the standard transverse rupture specimen as specified in Test
Method B406; that is, ground to the following dimensions:
4.1 Apolished and fully etched specimen/specimens having
5.00 6 0.25 mm (0.200 6 0.010 in) thick by 6.25 6 0.25 mm
a minimum observable area of 0.5 cm is examined using a
(0.250 6 0.010 in) wide by 19.0 mm (0.750 6 in) long.
Alternatively, the specimen shall be a size to provide a
This test method is under the jurisdiction of ASTM Committee B09 on Metal 2
minimum 0.5 cm surface area of examination, or it may
Powders and Metal Powder Productsand is the direct responsibility of Subcommit-
consist of several samples that provide this minimum area.
tee B09.06 on Cemented Carbides.
Current edition approved
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