1、Designation: B277 95 (Reapproved 2012)B277 18Standard Test Method forHardness of Electrical Contact Materials1This standard is issued under the fixed designation B277; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of las
2、t revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the hardness of metallic materials used for electrical contacts. Rockwell,Ro
3、ckwell superficial, Brinell, and microhardness microindentation hardness tests are included, along with information on thelimitations 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 mathematicalconversions to SI uni
4、ts 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 responsibilityof the user of this standard to become familiar will all hazards including those identified in
5、the appropriate Material Safety DataSheet (MSDS)(SDS) for this product/material as provided by the manufacturer, to establish appropriate safety safety, health, andhealthenvironmental practices, and determine the applicability of regulatory limitations prior to use.1.4 This international standard wa
6、s developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced
7、Documents2.1 ASTM Standards:2E10 Test Method for Brinell Hardness of Metallic MaterialsE18 Test Methods for Rockwell Hardness of Metallic MaterialsE384 Test Method for Microindentation Hardness of Materials3. Significance and Use3.1 The Rockwell hardness and Rockwell superficial tests are useful whe
8、n the test specimens are sufficiently thick (in relationto 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 piecethe flow of metal on the under surface may be detected by a bulge or marking. On composite pieces where the cont
9、act materialsare attached to backings of a different material, the thickness limitations imposed for a solid piece shall apply to the contactmaterial portion of such composite pieces.NOTE 1As a matter of information, it may be stated that tests on fine silver showed that on annealed samples having a
10、 Rockwell 15T hardness of27, the readings were not affected on thicknesses 116 in. (1.6 mm) or over. On thicknesses of 132 in. (0.8 mm) Rockwell 15T scale readings of 72 andhigher were not affected.3.2 The microhardness microindentation hardness test is of questionable significance when the metallic
11、 phases in a material areso large that the indentation does not represent an accurate average hardness. Sintered contact materials usually contain segregatesdiffering greatly in hardness from the matrix hardness and may destroy the validity of microhardness microindentation hardnessreadings.3.3 Othe
12、r aspects of significance and use shall be as described in the particular ASTM test method used, as listed in Section2.1 This test method is under the jurisdiction of ASTM Committee B02 on Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee B02.11 onElectrical Contact Test
13、Methods.Current edition approved May 1, 2012April 1, 2018. Published May 2012May 2018. Originally approved in 1952. Last previous edition approved in 20062012 asB277 95 (2006).(2012). DOI: 10.1520/B0277-95R12.10.1520/B0277-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or co
14、ntactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standardsstandards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what chang
15、es have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the offici
16、al document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Sampling4.1 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. P
17、rocedure5.1 Determine the hardness in accordance with one of the following:5.1.1 Test Methods E18 subject to the additional requirements and precautions in 3.1, 5.2, and 5.3.5.1.2 Test Method E384 subject to the additional requirements and precautions in 3.2 and 5.4.5.1.3 Test Method E10.5.2 When em
18、ploying the Rockwell superficial hardness test (Test Methods E18) the specimen hardness shall be within the rangeof the selected scale, as shown in Table 1.5.3 When using the Rockwell or Rockwell superficial hardness tests on contacts which are in rivet form, the shanks of suchrivets may have insuff
19、icient cross-sectional area to support the test pressure. In such cases the shank shall be removed to form aflat surface for placement against the anvil. The welding projection on contacts designed for assembly by projection welding shallalso be removed. Some rivet contacts are too small for the use
20、 of Rockwell superficial hardness testing, in which case themicrohardness microindentation hardness tests may be used.5.4 When employing the microhardness microindentation hardness test (Test Method E384) the minimum indentor load shallbe 100 gf, except for specimens that have a thickness or diamete
21、r less than 0.005 in. (0.13 mm) in which case a 25 or 50 gf loadshall be used.5.4.1 When microhardness microindentation hardness tests (Test Method E384) are employed at 100 gf or less load, make aminimum of five indentations. Obtain the reported microhardness microindentation hardness value by aver
22、aging these indentations.6. Reports6.1 In addition to the requirements of the applicable hardness method used, the report shall include the following:6.1.1 When it is necessary to make measurements on thin sections of material where results will be affected, this fact shall bestated in reporting the
23、 results, stating the thickness of the material tested.6.1.2 When tests are made on surfaces having a spherical or cylindrical curvature, the radius of curvature shall be given in thereport.7. Precision and Bias7.1 The precision and bias of this test method are as stated in the particular ASTM Test
24、Method used (see 2.1 and Note 1).NOTE 2Interlaboratory Knoop hardness tests at 100 gf on noble alloys in the range of approximately 170 to 230 HK indicate that measured diagonallengths have a standard deviation of approximately 1.4 m that corresponds to 5.3 to 7.5 Knoop numbers respectively.8. Keywo
25、rds8.1 contacts; electrical contact materials; hardness; microhardness microindentation hardnessASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determin
26、ation of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or wit
27、hdrawn.Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that you
28、r comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (sing
29、le or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 1 Permissible Hardness RangesScale Permitted Range15T 209030T 209045T 109015N 7010030N 4010045N 20100B277 182
