Rockwell hardness testing is one of the more important methods 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 Rockwell hardness testing the only test method to be considered in evaluating cemented carbides.

1.1 This test method covers the hardness testing of cemented carbides by use of a Rockwell hardness tester performing tests in the Rockwell HRA scale (regular scale, diamond indenter, 10 kgf (98.07 N) preliminary test force, and 60 kgf (588.4 N) load) in the range of Rockwell 80 HRA and above. Also covered are the procedures for the testing and selection of diamond indenters, the management and traceability of the four levels of standardized test blocks, and the making and calibration of Primary, Secondary, and Working standardized 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 The latest version of Test Methods E18 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 except that force and length values associated with the Rockwell hardness testers will comply with E18 with force values specified as N (kgf) and indenter length values specified as mm.

1.5 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.