Microform calibration uncertainties of Rockwell diamond indenters
- National Inst. of Standards and Technology, Gaithersburg, MD (United States)
The Rockwell hardness test is a mechanical testing method for evaluating a property of metal products. National and international comparisons in Rockwell hardness tests show significant differences. Uncertainties in the geometry of the Rockwell diamond indenters are largely responsible for these differences. By using a stylus instrument, with a series of calibration and check standards, and calibration and uncertainty calculation procedures, the authors have calibrated the microform geometric parameters of Rockwell diamond indenters. These calibrations are traceable to fundamental standards. The expanded uncertainties are {+-} 0.3 {micro}m for the least-squares radius; {+-} 0.01{degree} for the cone angle; and {+-} 0.025 for the holder axis alignment calibrations. Under ISO and NIST guidelines for expressing measurement uncertainties, the calibration and uncertainty calculation procedure, error sources, and uncertainty components are described, and the expanded uncertainties are calculated. The instrumentation and calibration procedure also allows the measurement of profile deviation from the least-squares radius and cone flank straightness. The surface roughness and the shape of the spherical tip of the diamond indenter can also be explored and quantified. The calibration approach makes it possible to quantify the uncertainty, uniformity, and reproducibility of Rockwell diamond indenter microform geometry, as well as to unify the Rockwell hardness standards, through fundamental measurements rather than performance comparisons.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 170267
- Journal Information:
- Journal of Research of the National Institute of Standards and Technology, Journal Name: Journal of Research of the National Institute of Standards and Technology Journal Issue: 5 Vol. 100; ISSN 1044-677X; ISSN JRITEF
- Country of Publication:
- United States
- Language:
- English
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