Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Establishing a World-Wide Unified Rockwell Hardness Scale Using Standard Diamond Indenters



S Desogus, A Germak, H Ishida, T Polzin, H Yang, Jun-Feng Song, Samuel Low, David J. Pitchure


Recently developed microform measurement techniques have reduced the measurement uncertainties in the geometry of Rockwell diamond indenters. It is now possible to establish standard grade Rockwell diamond indenters characterized by high geometry uniformity, High hardness performance uniformity, interchangeability and reproducibility. By using the standard indenters under different national standard machines and a standardized testing cycle a worldwide unified Rockwell hardness scale could be established with metrological traceability, stability and reproducibility. Geometrical measurements and hardness tests in five laboratories have shown that tightly controlled indenter geometry can significantly improve the consistency of Rockwell C hardness (HRC) measurements. These results support the feasibility of establishing a worldwide unified HRC scale with an expanded uncertainty (k = 2) of approximately +0.2 HRC and without significant bias with respect to an ideal scale.


diamond indenter, HRC, Rockwell hardness


Desogus, S. , Germak, A. , Ishida, H. , Polzin, T. , Yang, H. , Song, J. , Low, S. and Pitchure, D. (2017), Establishing a World-Wide Unified Rockwell Hardness Scale Using Standard Diamond Indenters, Measurement (Accessed April 23, 2024)
Created February 19, 2017