Investigation of wear mechanisms for the rake face of a cutting tool with a multilayer composite nanostructured Cr-CrN-(Ti,Cr,Al,SON coating in high-speed steel turning

The article considers the wear pattern for the rake face of a cutting tool with the Cr-CrN-(Ti,Cr,Al, SON multilayer composite nanostructured coating in turning 1045 steel at nu(c) = 300 m/min. Attention was paid to the diffusion and oxidation processes and effect of high temperature because these wear factors prevailed at high cutting speeds. Studies were conducted using a high-resolution transmission electron microscope and energy-dispersive X-ray spectroscopy. The study of the wear-crater boundary area revealed a layer with lost nanostructure (destruction layer) in the outer coating area. The thickness of the layer was 100-700 nm, depending on its location relative to the wear crater. The layer, which was formed under simultaneous exposure to high temperatures and diffusion and oxidation processes, was characterized by variable thickness and chemical composition, depending on its location relative to the wear crater. In particular, there are large volumes of oxygen in areas with freer access to air, while the oxygen content is significantly lower in the area of the bridge between the wear crater and cutting edge. The Al content increased significantly as the layer approached the cutting-edge area due to an increase in temperature and intensification of the spinodal decomposition process.