ASTM B277.pdf

Designation: B 277 – 95 (Reapproved 2006)

Standard Test Method for

Hardness of Electrical Contact Materials

1

This standard is issued under the fixed designation B 277; 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

1.1 This test method covers the determination of the hard-

only.

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

Material Safety Data Sheet (MSDS) for this product/material

as provided by the manufacturer, to establish appropriate

safety and health practices, and determine the applicability of

regulatory limitations prior to use.

2. Referenced Documents

E 384 Test Method for Microindentation Hardness of Ma-

terials

3. 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

3.2 The microhardness 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

4. Sampling

4.1 Prepare test samples in accordance with the method

selected from those listed in Section

2 and, where applicable,

supplemented with the requirements in 5.3.

5. Procedure

5.1 Determine the hardness in accordance with one of the

following:

5.1.1 Test Methods

E18 subject to the additional require-

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.

5.3 When using the Rockwell or Rockwell superficial hard-

ness tests on contacts which are in rivet form, the shanks of

such rivets may have insufficient cross-sectional area to sup-

port the test pressure. In such cases the shank shall be removed

to form a flat surface for placement against the anvil. The

approved in 1952. Last previous edition approved in 2001 as B 277 – 95 (2001).

For referenced ASTM standards, visit the ASTM website, www.astm.org, or

contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM

Standards volume information, refer to the standard’s Document Summary page on

the ASTM website.