Effects of temperature and loads on hardness and surface failure modes of cemented carbide

Abstract

Cemented carbide is a common cutting material with a hardness that significantly affects its usability. A Vickers indentation test was performed to analyse changes in the hardness of cemented carbide cutters with temperature and loads to understand its variation law. Moreover, indentation-induced surface damage was observed, and its elements were analysed. Crack distributions on the indentation surface were detected and analysed through an etching method. The results demonstrate that the hardness of cemented carbide decreases with greater temperatures and loads. At room temperature, the hardness of cemented carbide decreased from 1321 to 996 MPa when the loads increased from 300 to 800 N. When the external load was fixed at 500 N, the hardness of the cemented carbide decreased from 1113 to 939 MPa as the temperature increased from 25 to 350 °C. Moreover, the density of the indentation-induced surface damages increased with a reduction of the Vickers hardness. In addition, the mean free path of the binding phase for the cemented carbide with large grain sizes was relatively high. Therefore, it is difficult to generate diagonal cracks under large loads and high temperatures, which are beneficial to prevent cutter flaking.