ASTM B294-92(2006)
(Test Method)Standard Test Method for Hardness Testing of Cemented Carbides
Standard Test Method for Hardness Testing of Cemented Carbides
SIGNIFICANCE AND USE
Rockwell hardness is one of the more important properties used to evaluate cemented carbides. For compositional groups of cemented carbides, hardness is an indication of wear resistance and toughness. Lower hardness grades usually indicate less wear resistance but greater toughness. For a specific grade of cemented carbide, hardness is an indication of the metallurgical quality of the material. In no case is hardness the only property to be considered in evaluating cemented carbides.
SCOPE
1.1 This test method covers the hardness testing of cemented carbides by use of the Rockwell hardness tester with the Rockwell A scale (diamond indenter and 588.4 N (60 kgf) load) in the range of Rockwell A80 and above. Also covered are the procedures for the testing and selection of diamond indenters, the management and traceability of the four levels of standard test blocks, the acquisition of secondary standard test blocks, and the making and calibration of working standard test blocks.
1.2 The Rockwell hardness tester is a convenient and reliable means of measuring the hardness of cemented carbides. A hardness value is obtained easily, but it is subject to considerable error unless certain precautions are observed.
1.3 Test Methods E 18 shall be followed except where otherwise indicated in this test method.
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
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.
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Designation:B294–92(Reapproved 2006)
Standard Test Method for
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Hardness Testing of Cemented Carbides
This standard is issued under the fixed designation B 294; 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 ISO 3738-2 Hardmetals—Rockwell hardness test (Scale
A)—Part 2, Preparation and calibration of standard test
1.1 This test method covers the hardness testing of ce-
blocks
mented carbides by use of the Rockwell hardness tester with
the Rockwell A scale (diamond indenter and 588.4 N (60 kgf)
3. Significance and Use
load) in the range of Rockwell A80 and above. Also covered
3.1 Rockwell hardness is one of the more important prop-
are the procedures for the testing and selection of diamond
erties used to evaluate cemented carbides. For compositional
indenters,themanagementandtraceabilityofthefourlevelsof
groups of cemented carbides, hardness is an indication of wear
standard test blocks, the acquisition of secondary standard test
resistance and toughness. Lower hardness grades usually
blocks,andthemakingandcalibrationofworkingstandardtest
indicate less wear resistance but greater toughness. For a
blocks.
specificgradeofcementedcarbide,hardnessisanindicationof
1.2 The Rockwell hardness tester is a convenient and
the metallurgical quality of the material. In no case is hardness
reliable means of measuring the hardness of cemented car-
the only property to be considered in evaluating cemented
bides. A hardness value is obtained easily, but it is subject to
carbides.
considerable error unless certain precautions are observed.
1.3 Test Methods E18 shall be followed except where
4. Apparatus
otherwise indicated in this test method.
4.1 Scale—All hardness tests shall be made on the regular
1.4 The values stated in SI units are to be regarded as
(asopposedtosuperficial)Rockwelltester,usinga588.4N(60
standard. The values given in parentheses are for information
kgf) load (Rockwell A scale).
only.
4.2 Effect of Vibration—The Rockwell hardness tester
1.5 This standard does not purport to address all of the
should be located in a vibration-free area in order to avoid
safety concerns, if any, associated with its use. It is the
erroneous results. If this is not possible, the tester shall be
responsibility of the user of this standard to establish appro-
mounted so as to minimize vibrations, since vibrations tend to
priate safety and health practices and determine the applica-
cause erratic readings.
bility of regulatory limitations prior to use.
4.3 Indenter—The standard indenter shall be selected, in
2. Referenced Documents accordance with the Annex to this test method, from diamond
2 cone indenters specified for Rockwell A scale use and in
2.1 ASTM Standards:
conformance with Test MethodsE18.
E18 Test Methods for Rockwell Hardness and Rockwell
4.3.1 The indenter, and an indentation made with it, in
Superficial Hardness of Metallic Materials
hardened steel or cemented carbide should be examined
E29 Practice for Using Significant Digits in Test Data to
optically at approximately 50-diameter magnification for de-
Determine Conformance with Specifications
3 fects, conformance to shape, and mounting of the diamond.
2.2 ISO Standard:
Examination should be made when selecting an indenter,
occasionally during use, and whenever some event may be
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suspected of having damaged the diamond or its mounting.
This test method is under the jurisdiction of ASTM Committee B09 on Metal
Powders and Metal Powder Products and is the direct responsibility of Subcom-
4.4 Anvils—Select an anvil suitable for the specimen to be
mittee B09.06 on Cemented Carbides.
tested. The shoulder of the screw and the mating surface of the
Current edition approved April 1, 2006. Published April 2006. Originally
anvil should be clean. Seat the anvil securely. For the best
approved in 1954. Last previous edition approved in 2001 as B 294 – 92 (2001).
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accuracy, flat test pieces should be tested on a flat anvil of
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
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contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approximately 6-mm ( ⁄4-in.) diameter. The bearing surface of
Standards volume information, refer to the standard’s Document Summary page on
this anvil, with a Rockwell C hardness of at least 60, shall be
the ASTM website.
3 polished smooth and be free of pits and heavy scratches. The
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036. test piece should be supported suitably, with the test surface
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