Cutting performance and wear mechanisms of TiAlN PVD-coated cemented carbide tool in high speed turning of Ti-5Al-2Sn-2Zr-4Mo-4Cr alloy

Abstract

The high-speed finish turning tests of Ti-17 titanium alloy (Ti-5Al-2Sn-2Zr-4Mo-4Cr) were carried out by using PVD cemented carbide tools with TiAlN coating. The machinability behaviors in terms of cutting forces, cutting temperatures, surface roughness, and tool service life were measured and evaluated under different machining parameter conditions, and the empirical prediction model of these variables were established depending on the cutting parameters. Incorporating the measured results of scanning electron microscopy (SEM) as well as energy dispersive spectroscopy (EDS), the initial tool wear patterns and the eventual wear patterns when the tool wear states meet the failure criteria were comparably investigated and analyzed. It was found that during the initial wear stage, the sticking wear zone and the sliding wear zone can be distinguished on the tool wear interface. The main wear patterns of are peeling off of coating material, crater wear of rake face, edge breakage and edge wear of tool tip after reaching the tool failure rejection criterion. The cutting tool wear mechanisms were systematically studied, and the results show that the wear mechanisms of a TiAlN PVD-coated carbide cutting tool in turning Ti-17 titanium alloy were dominated by the interaction wear effect among the adhesion, oxidation and diffusion between cemented carbide substrate and workpiece material.