Wear and micromechanical performance of novel mono/bi-layered PVD-coated WC tools in high-speed turning of Ti-5Al-5V-5Mo-3Cr alloy

The Ti-5Al-5V-5Mo-3Cr alloy is utilized in the aerospace, biomedical, and military industries for its exceptional thermomechanical properties. However, its comparatively higher strength and toughness render it more difficult-to-cut than traditionally employed Ti alloys such as Ti-64. Despite its growing demand, a noticeable gap concerning the finish turning of Ti-5553 using coated carbide tools was identified. This paper aims to address this gap by conducting a comprehensive investigation of the tool life and micromechanical performance of novel mono/bi-layered PVD-coated WC tools under high-speed finish turning and wet conditions. A commercial AlTiN-based coating serves as the baseline reference layer and was compared with mono-layered ta-C (diamond-like carbon, DLC), AlCrN, and TiAlSiN coatings deposited atop the AlTiN base on three separate cutting tools. The study focused on evaluating the tool life and surface finish results of all the coatings. Demonstrating that the AlTiN/AlCrN coated tool exhibited the longest tool life, improvement of ~ 9.02% with reference to the baseline, while imparting the smoothest surface finish, an improvement of ~ 31.81%, on the workpiece material due to its optimal micromechanical properties and conducive oxide formation. The results obtained offer valuable insight into understanding the relationship between machining performance and coating properties, consequently allowing the industrial sector to refine its selection criteria to aid with productivity and quality assurance.