TEST-LOCATION SPECIFICATION BY MEANS OF HARDNESS MAPPING

Abstract The non-uniformity of the hardness reference block is one of the important factors, which influence the hardness measurement. For calibration of hardness reference block, the elementary idea to reduce the error from this factor is to make the indentations at the distributed location as though covering the entire test surface with limited number of indentations. The principle to decide the appropriate numbers and locations of the measurement is to consider the trend and frequency of hardness distribution. Stratified sampling was introduced to the study on the assumption that the confidence of average hardness estimation would be increase with an appropriate test location. Six Vickers hardness reference blocks of 200, 600, 900 HV from 2 different manufacturers were selected for the experiment