Wear mechanisms and tool performance of TiAlN PVD coated inserts during machining of AISI 4140 steel

The tribological influences of PVD-applied TiAlN coatings on the wear of cemented carbide inserts and the microstructure wear behaviors of the coated tools under dry and wet machining are investigated. The turning test was conducted with variable high cutting speeds ranging from 210 to 410 m/min. The analyses based on the experimental results lead to strong evidences that conventional coolant has a retarded effect on TiAlN coatings under high-speed machining. Micro-wear mechanisms identified in the tests through SEM micrographs include edge chipping, micro-abrasion, micro-fatigue, micro-thermal, and micro-attrition. These micro-structural variations of coatings provide structure-physical alterations as the measures for wear alert of TiAlN coated tool inserts under high speed machining of steels.