ASTM B930-03

Standard Test Method for Rating Grain Size and Frequency of Abnormally Large Grains in Cemented Tungsten Carbides (Hardmetals)

SIGNIFICANCE AND USE
The microstructure and grain growth of cemented tungsten carbides affect the material’mechanical and physical properties. The grain size and distribution will affect the material’wear resistance and fracture toughness. Abnormally large grains as compared to the background may introduce an area of weakness in a sintered part.
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

• Status: Historical
• Publication Date: 30-Sep-2003
• ICS: 77.160 - Powder metallurgy
• Technical Committee: B09 - Metal Powders and Metal Powder Products
• Drafting Committee: B09.06 - Cemented Carbides

Relations

• Replaced By: ASTM B930-03(2008) - Standard Test Method for Rating Grain Size and Frequency of Abnormally Large Grains in Cemented Tungsten Carbides (Hardmetals)
• Effective Date: 01-Apr-2008

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:B930–03
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 B 930; 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 categorized as: (1)The number of grains larger than a specified
size, or (2) The largest grain observed, or both.
1.1 This test method describes a procedure for measuring
abnormally large grains and the frequency of those grains in
5. Significance and Use
cemented tungsten carbides (hardmetals).
5.1 The microstructure and grain growth of cemented tung-
1.2 This standard does not purport to address all of the
sten carbides affect the material’s mechanical and physical
safety concerns, if any, associated with its use. It is the
properties. The grain size and distribution will affect the
responsibility of the user of this standard to establish appro-
material’s wear resistance and fracture toughness. Abnormally
priate safety and health practices and determine the applica-
large grains as compared to the background may introduce an
bility of regulatory limitations prior to use.
area of weakness in a sintered part.
2. Referenced Documents 5.2 This test method may be used in acceptance testing of
cemented tungsten carbide materials or the tungsten carbide
2.1 ASTM Standards:
powderusedintheirmanufacture.Thespecifiedgrainsizeused
B 243 Terminology of Powder Metallurgy
for the E-Rating is to be agreed upon between purchaser and
B 406 Test Method for Transverse Rupture Strength of
supplier.
Cemented Carbides
B 657 Test Method for Metallographic Determination of
6. Apparatus
Microstructure in Cemented Tungsten Carbides
6.1 Metallographic Microscope, capable of magnifications
B 665 Guide for Metallographic Sample Preparation of
of up to 15003.
Cemented Tungsten Carbides
6.2 Ordinary metallurgical laboratory equipment.
3. Terminology 6.3 Equipment for specimen preparation as outlined in
Guide B 665.
3.1 Definitions—Definitions of powder metallurgy terms
can be found in Terminology B 243.
7. Test Specimens
3.2 Definitions of Terms Specific to This Standard:
7.1 Specimen Size—The recommended specimen shall be
3.2.1 E-Rating—the number/cm of grains larger than a
the standard transverse rupture specimen as specified in Test
specified size in a fully-etched specimen.
Method B 406; that is, ground to the following dimensions:
3.2.2 L-Rating—the size, in µm, of the largest grain ob-
5.00 6 0.25 mm (0.200 6 0.010 in) thick by 6.25 6 0.25 mm
served in a fully-etched specimen.
(0.250 6 0.010 in) wide by 19.0 mm (0.750 6 in) long.
4. Summary of Test Method Alternatively, the specimen shall be a size to provide a
minimum 0.5 cm surface area of examination, or it may
4.1 Apolished and fully etched specimen/specimens having
consist of several samples that provide this minimum area.
a minimum observable area of 0.5 cm is examined using a
7.2 Specimen Preparation:
metallograph. Abnormally large grains, compared to the finer-
7.2.1 Polish the specimen/specimens accord
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