Impact of Process Parameters on Machining-Induced Micro-Hardness in Dry End Milling of Inconel 625 Using Coated Tool

Abstract

Super alloys, such as nickel-based alloy Inconel 625, are capable of maintaining their excellent mechanical properties, even after extended contact with high temperatures. The class of super alloys was mainly developed for the components of aircraft turbine engines as well as turbo-superchargers and many other industrial uses, such as oil and petroleum refineries, chemical plants, gas turbines and rocket engines. However, they are difficult to cut during the machining process and induce high micro-hardness on machined surface. Machining-induced micro-hardness has been generally recognized as one of the key factors among all surface integrity parameters. Micro-hardness measurements are considered significant in the determination of wear and corrosion resistance as well as to obtain an in depth understanding of machining-affected region. This study was carried out to investigate the machining-induced micro-hardness of Inconel 625, during the end milling under dry environments with ultra-hard coating. ANOVA in combination with mean effect plot was applied for the analyses of micro-hardness. ANOVA results indicated the R² value as 98.16%, very close to 1, implying that the model terms are significant. Cutting speed and depth of cut were observed as the prime factors on machining-induced micro-hardness. Minimum micro-hardness (266 HV) was obtained at a higher feed per tooth, lower cutting speed, higher depth of cut and positive radial rake angle.