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Assessment of Error Sources in Rockwell Hardness Measurements



Walter S. Liggett Jr, Samuel Low, David J. Pitchure, Jun-Feng Song


In the use of hardness test blocks, the uncertainty due to block non-uniformity can be reduced if one is willing to make measurements at specified locations on the blocks. Statistical methods for achieving this reduction are explained in this paper. The test block uses considered include assessment of repeatability and reproducibility and comparison of testing machines and indenters. The methods are based on measurement at the vertices and centers of regular hexagons laid out on block surfaces. Measurements from such locations can be combined to give results that would not be influenced by block non-uniformity were the hardness to have constant gradient across individual hexagons. Although they do not eliminate the effects of block non-uniformity completely, the methods described reduce these effects and, in addition, allow them to be more easily treated in the analysis of the measurements.


experimental design, indentation hardness, measurement uncertainty, statistical methods, trend elimination


Liggett Jr, W. , Low, S. , Pitchure, D. and Song, J. (2008), Assessment of Error Sources in Rockwell Hardness Measurements, IMEKO TC (Accessed April 12, 2024)
Created October 16, 2008