Evaluation of a worn out WC-Co-TiAlN cutting tool used in industry

In this work, a cutting tool with premature wear was characterized by Rockwell hardness test, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). In addition, electrochemical impedance spectroscopy (EIS) measurements were carried out in order to investigate the characteristic properties of the wear coating (TiAlN) of tool (WC-Co substrate). The substrate hardness was 90 HRA, which is in accordance with the observed microstructure of a cobalt matrix with tungsten carbides. SEM-EDS analysis confirmed the presence of a TiAlN coating and of typical features of an adhesive wear mechanism. EIS results revealed typical behavior of a porous WC-C substrate. Hence, premature wear of cutting tool could be explained in terms of an inadequate performance of the defects of coating deposited on the WC-Co substrate, as suggested by porosity revealed in the SEM images and the EIS measurements.