Cutting Performance And Failure Mechanisms Of Coated Tools When Milling Inconel718

High-temperature alloys are a kind of the indispensable materials in the field of national defense and economic construction. Because of the superior properties, Inconel718is widely used in aerospace, nuclear and petrochemical industry, and is a typical difficult-to-machine material with stable structure organization, low thermal conductivity and high tendency to work-hardening. And the high cutting force and temperature when machining, as well as the severe tool wear restrict the machined surface quality. In this thesis, tool selection, chip formation, surface roughness, cutting force, and tool failure mechanisms in milling of Inconel718with coated carbide tools were systematically investigated.Thermal residual stress in the deposition process of coated carbide tools is analyzed by using finite element analysis software. In the simulation, Thermal residual stresses of both single-layer and multi-layer coated tools are considered. The effect of coating and substrate material properties and coating structure on Thermal residual stress are also discussed. This research provides a theoretical guidance for the selection of coated carbide tools when machining Inconel718.Gibbs free energy is calculated in the cutting process applying the thermodynamics theory. The results indicate that chemical reaction exist among tool material, workpiece material and surrounding medium, which provide a theoretical basis for analysis of nickel-base alloy machining process and tool failure.Milling experiments for Inconel718were conducted with solid carbide coated tools. At first, the influence of the cutting parameters on the machined surface roughness in milling experiments was discussed and the effects of the chip morphology on the machining performance were revealed. Secondly, the transient cutting forces in the experiments were measured, the magnitude and variation of the cutting force were analyzed, and the influence of the different cutting parameters on the cutting force was discussed. At last, the milling experiments are carried out on Inconel718with indexable coated carbide inserts, and the influence of tool wear on the cutting force was investigated. Combining the analysis of SEM and EDS, the wear patterns and failure mechanisms of coated carbide tools were revealed. This provides the basis for optimizing the cutting process, improving the machined surface quality and tool life.