ASTM B277-95(2006)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:B277–95(Reapproved2006)
Standard Test Method for
Hardness of Electrical Contact Materials
This standard is issued under the fixed designation B277; 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 contact materials are attached to backings of a different
material, the thickness limitations imposed for a solid piece
1.1 This test method covers the determination of the hard-
shall apply to the contact material portion of such composite
ness of metallic materials used for electrical contacts. Rock-
pieces.
well, Rockwell superficial, Brinell, and microhardness tests are
included, along with information on the limitations and use of
NOTE 1—As a matter of information, it may be stated that tests on fine
these tests.
silver showed that on annealed samples having a Rockwell 15T hardness
of 27, the readings were not affected on thicknesses ⁄16 in. (1.6 mm) or
1.2 The values stated in inch-pound units are to be regarded
over. On thicknesses of ⁄32 in. (0.8 mm) Rockwell 15T scale readings of
as the standard. The SI units in parentheses are for information
72 and higher were not affected.
only.
1.3 This standard does not purport to address all of the 3.2 The microhardness test is of questionable significance
when the metallic phases in a material are so large that the
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to become familiar indentation does not represent an accurate average hardness.
Sintered contact materials usually contain segregates differing
will all hazards including those identified in the appropriate
Material Safety Data Sheet (MSDS) for this product/material greatly in hardness from the matrix hardness and may destroy
the validity of microhardness readings.
as provided by the manufacturer, to establish appropriate
safety and health practices, and determine the applicability of 3.3 Other aspects of significance and use shall be as
described in the particularASTM test method used, as listed in
regulatory limitations prior to use.
Section 2.
2. Referenced Documents
2 4. Sampling
2.1 ASTM Standards:
E10 Test Method for Brinell Hardness of Metallic Materials 4.1 Prepare test samples in accordance with the method
E18 Test Methods for Rockwell Hardness of Metallic Ma- selected from those listed in Section 2 and, where applicable,
supplemented with the requirements in 5.3.
terials
E384 Test Method for Microindentation Hardness of Mate-
5. Procedure
rials
5.1 Determine the hardness in accordance with one of the
3. Significance and Use
following:
5.1.1 Test Methods E18 subject to the additional require-
3.1 The Rockwell hardness and Rockwell superficial tests
are useful when the test specimens are sufficiently thick (in ments and precautions in 3.1, 5.2, and 5.3.
5.1.2 Test Method E384 subject to the additional require-
relation to the indentor load) to ensure that the results are not
affected by the flow of metal on the surface of the anvil. On a ments and precautions in 3.2 and 5.4.
5.1.3 Test Method E10.
solid piece the flow of metal on the under surface may be
detectedbyabulgeormarking.Oncompositepieceswherethe 5.2 When employing the Rockwell superficial hardness test
(Test Methods E18) the specimen hardness shall be within the
range of the selected scale, as shown in Table 1.
This test method is under the jurisdiction of ASTM Committee B02 on
5.3 When using the Rockwell or Rockwell superficial hard-
Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee
ness tests on contacts which are in rivet form,
...