Recent developments in standard hardness machines and microform calibration techniques have made it possible to establish a worldwide unified Rockwell hardness scale with metrological traceability. This includes the establishments of the reference standards (standard machines and diamond indenters) traceable to fundamental measurements of force, time, and length, and the reference testing conditions (a standardized common testing cycle) based on an international agreement. Standard grade Rockwell diamond indenters play a key role to a worldwide unified Rockwell hardness scale. In 1994, NIST (National Institute of Standard and Technology) established a microform calibration system with sufficiently small measurement uncertainty for calibrating standard Rockwell indenters. In 1995, NIST calibrated a group of 11 Rockwell diamond indenters which were characterized both by high geometrical uniformity and hardness performance uniformity. One of them was used as NIST master standard indenter for calibrating NIST SRM (Standard Reference Material) Rockwell hardness blocks. After about three years of use for more than 3000 indentations, this NIST master indenter was re-calibrated. The calibration results showed high stability for both the microform geometry and hardness performance of the NIST standard Rockwell diamond indenters, as well as high measurement reproducibility for the NIST microform calibration system.
Proceedings Title: Proceedings of 1998 International Symposium on Advances in Hardness Measurement
Conference Dates: September 21-23, 1998
Conference Location: Beijing, CN
Conference Title: International Symposium on Advances in Hardness Measurement
Pub Type: Conferences
diamond indenter, HRC, Rockwell hardness, traceability, worldwide unified Rockwell scale