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Establishing a Worldwide Unified Rockwell Hardness Scale With Metrology Traceability



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


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 national 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 of approximately ¿ 0.2 HRC and without significant bias with respect to an ideal scale.


diamond indenter, HRC, Rockwell hardness


Song, J. , Low, S. , Pitchure, D. , Germak, A. , Desogus, S. , Polzin, T. , Yang, H. , Ishida, H. and Barbato, G. (1997), Establishing a Worldwide Unified Rockwell Hardness Scale With Metrology Traceability, Metrologia (Accessed March 3, 2024)
Created December 31, 1996, Updated October 12, 2021