Investigation of the machinability of the inconel 718 nickel alloys by electro - thermal machining processes

Investigation of The Machinability of The Inconel 718 Nickel Alloys by Electro - Thermal Machining ProcessesAlthough a widespread usage area of Inconel 718 nickel based superalloys, these alloys are classified as difficult to cut materials due to the low thermal conductivity, hardness, work hardening. Considering the usage areas of these alloys, it is restricted to machine these alloys in high tolerances and complex shapes by traditional machining processes, especially for the big size plates. Thus, the thermal machining processes facilitate to machine this alloy by a more economical way. Owing to these reasons, in this study, the different age hardened Inconel 718 nickel based superalloy at different temperature and times was machined by there different thermal processes namely, laser beam machining (LBM), plasma arc cutting (PAC) and wire electrical discharge machining (WEDM). The effects of cutting parameters on the machining quality were investigated experimentally and by the help of computer programmers for the each processes. At the end of the experiments, the surface and heat affected zones of the samples were metallographically observed by scanning electron microscope (SEM), atomic force microscope (AFM), dispersive spectrograph (EDS), X ? ray diffraction (XRD) and surface hardness measurements. Some characteristic changes such as the roughness of the machined surfaces, microstructural changes, recast layer thickness, kerf wides, kerf taper ratios and the effect of thermal conductivity factor of the material on the machining quality were the main performance characteristics under investigation. The relative effects of machining parameters were evaluated statistically and optimized for the three machining processes. Additionally, the processes were modeled by using the linear regression approach. The adequacies of models were checked by analysis of variance (ANOVA) and residual analysis techniques. As a consequence, it is concluded that the developed models could be used to predict the all machining processes without making experiments for the future works.Keywords: Inconel 718, laser cutting, plasma arc cutting, wire electrical discharge machining, analysis of variance, modeling.