ASTM B390-92(2006)
(Practice)Standard Practice for Evaluating Apparent Grain Size and Distribution of Cemented Tungsten Carbides (Withdrawn 2010)
Standard Practice for Evaluating Apparent Grain Size and Distribution of Cemented Tungsten Carbides (Withdrawn 2010)
SIGNIFICANCE AND USE
The apparent size and distribution of tungsten carbide grains in cemented carbides affects the material’wear resistance and fracture. For a given chemical composition, an increase in the average grain size will result in increased toughness and decreased wear resistance. This practice illustrates representative micro-structures for a wide range of tungsten carbide-cobalt grades. This is not intended to be used as a specification for carbide grades; producers and users may use the micrographs and the grain size chart as a guide in developing their own specifications.
SCOPE
1.1 This practice for the visual comparison and classification of the apparent grain size and distribution of cemented tungsten carbides is limited to cemented tungsten carbides that contain approximately 6, 10, and 18 % cobalt.
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.
WITHDRAWN RATIONALE
This practice for the visual comparison and classification of the apparent grain size and distribution of cemented tungsten carbides was limited to cemented tungsten carbides that contain approximately 6, 10, and 18 % cobalt.
Formerly under the jurisdiction of Committee B09 on Metal Powders and Metal Powder Products, this practice was withdrawn in September 2010. This practice was withdrawn without replacement since it has shown little use in the industry. Also, all of the photomicrographs needed to be replaced with photomicrographs with micron markers, which would be difficult to reproduce.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: B390 – 92 (Reapproved 2006)
Standard Practice for
Evaluating Apparent Grain Size and Distribution of
Cemented Tungsten Carbides
This standard is issued under the fixed designation B390; 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 tungsten carbide-cobalt grades. This is not intended to be used
as a specification for carbide grades; producers and users may
1.1 This practice for the visual comparison and classifica-
use the micrographs and the grain size chart as a guide in
tion of the apparent grain size and distribution of cemented
developing their own specifications.
tungsten carbides is limited to cemented tungsten carbides that
contain approximately 6, 10, and 18 % cobalt.
5. Specimen Preparation
1.2 This standard does not purport to address all of the
5.1 Specimens shall be prepared for metallographic exami-
safety concerns, if any, associated with its use. It is the
nation in accordance with a procedure suitable for this type of
responsibility of the user of this standard to establish appro-
cemented carbides.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
NOTE 1—A suitable procedure is described in Test Method B657 and
Practice B665.
2. Referenced Documents
6. Procedure
2.1 ASTM Standards:
6.1 Examine metallographically the entire surface of an
B657 Guide for Metallographic Identification of Micro-
structure in Cemented Carbides etched specimen at a magnification of 1500 diameters. Select a
representative area and make a comparison with the photomi-
B665 Guide for Metallographic Sample Preparation of Ce-
mented Tungsten Carbides crographs in Figs. 1-3.
6.2 The nominal analyses of the cemented tungsten carbide
3. Terminology
samples that were used to prepare the nine photomicrographs
3.1 Definitions of Terms Specific to This Standard: shown in Figs. 1-3 are as follows:
3.1.1 apparent grain size—the average diameter of a tung- 6.2.1 Fig. 1—Tungsten carbide plus 6 % cobalt,
sten carbide particle as measured on an etched metallographi- 6.2.2 Fig. 2—Tungsten carbide plus 10 % cobalt, and
cally polished surface of a specimen of sintered cemented 6.2.3 Fig. 3—Tungsten carbide plus 18 % cobalt.
carbide. The apparent grain size is expressed in micrometres 6.3 The grain size for each of these specimens may be
and is generally reported as a range. designated as follows:
Type F—Fine grain,
4. Significance and Use
Type M—Medium grain, and
4.1 The apparent size and distribution of tungsten carbide
Type C—Coarse grain.
grains in cemented carbides affects the material’s wear resis-
7. Evaluation
tance and fracture. For a given chemical composition, an
increase in the average grain size will result in increased 7.1 The grain size rating of a cemented tungsten carbide
toughness and decreased wear resistance. This practice illus- specimen is accomplished by selecting the photomicrographs
trates representative micro-structures for a wide range of in Figs. 1-3 that most nearly match the field observed on the
specimen being evaluated (see Appendix X1).
7.2 A range of numerical values for various concentrations
This practice is under the jurisdiction of ASTM Committee B09 on Metal
of tungsten carbide particles, even though arbitrary, is sug-
Powders and Metal Powder Products and is the direct responsibility of Subcom-
gested in Table 1.
mittee B09.06 on Cemented Carbides.
Current edition approved April 1, 2006. Published April 2006. Originally
approved in 1962. Last previous edition approved
...
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