The bilateral comparison APMP.M.H-S2 of hardness measurement for Rockwell scales A and B was arranged by the National Institute of Metrology of Thailand, NIMT, as the pilot laboratory, comparing with Physikalisch-Technische Bundesanstalt of Germany, PTB. The objective of this comparison was to confirm the calibration and measurement capabilities of NIMT in hardness measurement. The period of measurement covered March to August 2009. There were two sets of artefacts: scale A artefact set and scale B artefact set. The scale A artefact set consisted of seven hardness blocks: 35 HRA, 40 HRA, 55 HRA, 60 HRA, 70 HRA, 80 HRA, 85 HRA. The artefact set for scale B consisted of nine hardness blocks: 25 HRB, 30 HRB, 40 HRB, 50 HRB, 60 HRB, 70 HRB, 80 HRB, 90 HRB, 100 HRB. Laboratories had to ensure that the primary Rockwell hardness machines passed the verification process according to ISO 6508-3. Then participants measured the hardness value by making ten indentations in a designated area of each artefact block. Hardness measurement results and uncertainty budget were then reported to the pilot laboratory and were used to compute the degrees of equivalence in terms of the Comparison Reference Value (CRV) and E_n ratio.

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The final report has been peer-reviewed and approved for publication by APMP, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).