Since the 1980's, the European Community (EC) has established a unified Rockwell C hardness (HRC) scale by averaging several national scales, which come from each country''s national hardness machines and diamond indenters. These indenters have significant differences in both microform geometry measurements and hardness tests. A hardness comparison and correction method is used to offset these differences. This method lacks metrological traceability and reproducibility. The EC unified scale has an unknown offset to an ideal scale. Instead, we propose a metrological approach using NIST standard grade Rockwell indenters whose development is motivated by a recently implemented microform calibration system. The proposed standard indenters would be characterized by high uniformity in both microform geometry and hardness performance, and, therefore, would be interchangeable and reproducible. By using standard indenters in standard hardness machines under a standardized testing cycle, it should be possible to establish a worldwide unified Rockwell scale with metrological traceability and reproducibility, and without significant bias to the ideal scale. Recent geometric measurements and hardness testing results support this approach.
Proceedings Title: Proceedings of 1996 National Conference of Standards Laboratories Workshop and Symposium
Conference Dates: January 1, 1996
Conference Location: Unknown, USA
Conference Title: 1996 National Conference of Standards Laboratories Workshop and Symposium
Pub Type: Conferences
calibration, diamond indenter, HRC, microform, Rockwell hardness, traceability