ASTM B277-18(2024)
(Test Method)Standard Test Method for Hardness of Electrical Contact Materials
Standard Test Method for Hardness of Electrical Contact Materials
SIGNIFICANCE AND USE
3.1 The Rockwell hardness and Rockwell superficial tests are useful when the test specimens are sufficiently thick (in 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 solid piece the flow of metal on the under surface may be detected by a bulge or marking. On composite pieces where the contact materials are attached to backings of a different material, the thickness limitations imposed for a solid piece shall apply to the contact material portion of such composite pieces.
Note 1: As a matter of information, it may be stated that tests on fine silver showed that on annealed samples having a Rockwell 15T hardness of 27, the readings were not affected on thicknesses 1/16 in. (1.6 mm) or over. On thicknesses of 1/32 in. (0.8 mm) Rockwell 15T scale readings of 72 and higher were not affected.
3.2 The microindentation hardness test is of questionable significance when the metallic phases in a material are so large that the indentation does not represent an accurate average hardness. Sintered contact materials usually contain segregates differing greatly in hardness from the matrix hardness and may destroy the validity of microindentation hardness readings.
3.3 Other aspects of significance and use shall be as described in the particular ASTM test method used, as listed in Section 2.
SCOPE
1.1 This test method covers the determination of the hardness of metallic materials used for electrical contacts. Rockwell, Rockwell superficial, Brinell, and microindentation hardness tests are included, along with information on the limitations and use of these tests.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.3 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 become familiar will all hazards including those identified in the appropriate Safety Data Sheet (SDS) for this product/material as provided by the manufacturer, to establish appropriate safety, health, and environmental practices, and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: B277 − 18 (Reapproved 2024)
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 3. Significance and Use
3.1 The Rockwell hardness and Rockwell superficial tests
1.1 This test method covers the determination of the hard-
are useful when the test specimens are sufficiently thick (in
ness of metallic materials used for electrical contacts.
relation to the indentor load) to ensure that the results are not
Rockwell, Rockwell superficial, Brinell, and microindentation
affected by the flow of metal on the surface of the anvil. On a
hardness tests are included, along with information on the
solid piece the flow of metal on the under surface may be
limitations and use of these tests.
detected by a bulge or marking. On composite pieces where the
1.2 The values stated in inch-pound units are to be regarded
contact materials are attached to backings of a different
as standard. The values given in parentheses are mathematical
material, the thickness limitations imposed for a solid piece
conversions to SI units that are provided for information only
shall apply to the contact material portion of such composite
and are not considered standard.
pieces.
1.3 This standard does not purport to address all of the
NOTE 1—As a matter of information, it may be stated that tests on fine
safety concerns, if any, associated with its use. It is the
silver showed that on annealed samples having a Rockwell 15T hardness
responsibility of the user of this standard to become familiar
of 27, the readings were not affected on thicknesses ⁄16 in. (1.6 mm) or
will all hazards including those identified in the appropriate
over. On thicknesses of ⁄32 in. (0.8 mm) Rockwell 15T scale readings of
72 and higher were not affected.
Safety Data Sheet (SDS) for this product/material as provided
by the manufacturer, to establish appropriate safety, health,
3.2 The microindentation hardness test is of questionable
and environmental practices, and determine the applicability
significance when the metallic phases in a material are so large
of regulatory limitations prior to use.
that the indentation does not represent an accurate average
1.4 This international standard was developed in accor-
hardness. Sintered contact materials usually contain segregates
dance with internationally recognized principles on standard-
differing greatly in hardness from the matrix hardness and may
ization established in the Decision on Principles for the
destroy the validity of microindentation hardness readings.
Development of International Standards, Guides and Recom-
3.3 Other aspects of significance and use shall be as
mendations issued by the World Trade Organization Technical
described in the particular ASTM test method used, as listed in
Barriers to Trade (TBT) Committee.
Section 2.
2. Referenced Documents
4. Sampling
2.1 ASTM Standards:
4.1 Prepare test samples in accordance with the method
E10 Test Method for Brinell Hardness of Metallic Materials
selected from those listed in Section 2 and, where applicable,
E18 Test Methods for Rockwell Hardness of Metallic Ma-
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
following:
5.1.1 Test Methods E18 subject to the additional require-
This test method is under the jurisdiction of ASTM Committee B02 on
ments and precautions in 3.1, 5.2, and 5.3.
Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee
B02.05 on Precious Metals and Electrical Contact Materials and Test Methods.
5.1.2 Test Method E384 subject to the additional require-
Current edition approved April 1, 2024. Published May 2024. Originally
ments and precautions i
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