Volume 24, Issue 2 (March 1996)
Minimum Thickness Requirements for Rockwell Hardness Testing
A study was performed in an attempt to resolve the conflicting thickness requirements for Rockwell hardness testing specified in ASTM Standard Test Methods E 18-93 and in ISO Standard 6508. Commercial standardized hardness test blocks were machined to “steps” of various thicknesses using a wire EDM (electrical discharge machining) process. Rockwell hardness tests were performed on the original standardized surface of these “stepped” blocks in an attempt to determine the minimum thicknesses required for reliable Rockwell hardness testing. The extremes of test force and hardness were investigated for both the diamond brale and 1/16 in. (1.588 mm) ball indenters.