ASTM B665-92(1997)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: B 665 – 92 (Reapproved 1997)
Standard Practice for
Metallographic Sample Preparation of Cemented Tungsten
Carbides
This standard is issued under the fixed designation B 665; 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 and diamond powders for lapping. The grinding practices
differ, to a minor degree, with respect to grit size of diamond.
1.1 This practice prescribes a method for preparing ce-
In all practices, however, the final polish is produced by
mented carbides for metallographic examination.
extremely fine diamond powder lapping, and in all practices
1.2 This standard does not purport to address all of the
care must be exercised to retain the microstructure in its true
safety concerns, if any, associated with its use. It is the
form and to avoid pull-out of the softer matrix material (usually
responsibility of the user of this standard to establish appro-
cobalt). While it is accepted that other procedures may be used
priate safety and health practices and determine the applica-
successfully, this procedure has proved satisfactory in many
bility of regulatory limitations prior to use.
laboratories.
2. Referenced Documents
5.1.1 Mounting—Where possible, specimens should be
mounted in a plastic material such as phenol-formaldehyde or
2.1 ASTM Standards:
poly(methyl methacrylate) to facilitate polishing without
B 390 Practice for Evaluating Apparent Grain Size and
rounding the edges. Larger specimens may be polished without
Distribution of Cemented Tungsten Carbides
mounting. When specimens are too large they may be sec-
B 657 Test Method for Metallographic Determination of
tioned using a diamond cut-off wheel or they may be fractured
Microstructure in Cemented Tungsten Carbides
(appropriate safety precautions should be utilized when frac-
3. Significance and Use
turing specimens). The area selected for examination should
represent, as nearly as possible, the entire cross section.
3.1 This sample preparation procedure may be used to
5.1.2 Rough Grinding—The surface to be examined may be
prepare metallographic samples for Test Method B 657 and
ground flat on a surface grinder with a resin-bonded diamond
Practice B 390. It does not include all variations of sample
wheel (100 to 220 grit) operated at 5000 to 5500 surface feet
preparation.
per minute (25 to 28 m/s). After the surface is flat, several
4. Selection of Specimen
clean-up passes are required; the maximum depth of cut is
0.0005 in. (13 μm) per pass and copious amounts of coolant are
4.1 Cemented tungsten carbides are very often in the form
used.
of relatively small pieces; it is possible to select and mount the
5.1.3 Polishing—Polishing is done in three steps using
entire piece in such manner as to permit examination of the
diamond powder or paste on a synthetic short-napped cloth (the
entire cross section. When pieces are too large for this,
reverse side of photographic paper, or manila file folders may
however, they should be sectioned, using a diamond cutoff
also be used). When automatic polishing equipment is used, a
wheel, to allow viewing as much of a representative cross
r
...