The influence of geometrical tolerances of Vickers indenter on the accuracy of measured hardness

¹ Faculty of Engineering, Cairo University, Gamaet El Qahera St. Giza, Giza, Egypt
² National Institute for Standards (NIS), 136 Tersa St., Mahatet El Matbaa, EL HARAM, Cairo, Egypt

^⋆ Correspondence: rihamhegazy@yahoo.com

Received: 27 March 2012
Accepted: 27 March 2012

Abstract

This paper reports work carried out to determine the influence of the Pyramidal indenter geometrical errors and tolerances on the accuracy of Vickers hardness measurements. The angle between the opposite faces and line of conjunction of nine indenters were measured by the optical comparator. The influence of the indenter geometry on the hardness accuracy is investigated. Three calibrated reference hardness test blocks were used to check the Vickers hardness test using the nine selected indenters. The results show that the geometrical error of the indenters (specially the angles) considerably affects the accuracy of the hardness measurement. Finite element analysis of the indentation process into metallic test pieces was conducted. Comparison of the experimental results with the numerical findings was discussed. Errors in the experimental values are correlated with measured tolerances in the angles between faces.