DEVELOPMENT OF NIST STANDARD REFERENCE METERIAL (SRM) ROCKWELL HARDNESS DIAMOND INDENTERS |
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| J. Song, S. Low |
- Abstract:
- The National Institute of Standards and Technology (NIST) is developing Standard Reference Material (SRM) Rockwell Hardness Diamond Indenters to support Rockwell hardness standardization in the U.S. One of the key steps is the geometrical calibration of the SRM indenters. Most tolerances for the geometrical parameters of the SRM indenters are adopted from those of the calibration grade Rockwell diamond indenters specified in the ASTM and ISO standards except for the form deviation from tip radius which was specified with a smaller tolerance of ± 0.8 µm. From the initial calibration results of the SRM indenters, it was found that the 0.5 µm tolerance for the cone flank straightness specified for the calibration grade diamond indenters by the ISO standard might be too tight to fit in the current production capability of the diamond manufacturers in different countries. As a result, although most SRM diamond indenters calibrated at NIST could meet all the technical requirements including the ± 0.8 µm reduced tolerance for the form deviation from the tip radius, none could meet the 0.5 µm tolerance of the cone flank straightness specified in the ISO standard when the calibrations were performed under the nominal window size. Furthermore, the window size and location for the geometrical calibration of the Rockwell diamond indenters are not clearly specified in the current standards, that also makes the geometrical calibration of Rockwell diamond indenter more difficult.
- Keywords:
- Rockwell hardness, diamond indenter, form deviation, microform calibration, standard reference material
- Download:
- IMEKO-WC-2012-TC5-O5.pdf
- DOI:
- -
- Event details
- Event name:
- XX IMEKO World Congress
- Title:
Metrology for Green Growth
- Place:
- Busan, REPUBLIC of KOREA
- Time:
- 09 September 2012 - 12 September 2012