Influence of grinding parameters on Inconel 625 surface grinding

Abstract

Nickel-based alloys have been increasingly employed due to their ability to maintain high mechanical strength and high chemical inertia at high temperatures. However, these outstanding properties can impair their machinability, so they are termed difficult-to-machine materials. Since machining of nickel alloys becomes even more difficult when the grinding process is needed, and because of poor thermal conductivity of both workpiece and the abrasive grinding wheel, more attention from machinists is required to determine proper grinding parameters that should be more moderate than those usually selected for grinding hardened steels. Because of the peculiar properties of Inconel 625 alloy, such as resistance to aqueous solutions, hot corrosion, high strength and resistance to creep, it makes it well suited for a wide range of applications, such as aerospace and marine applications as well as oil and gas industries. The grinding operation is generally the first option to enhance the combinations of narrow dimensional and geometric deviations in most of aeronautical components. In this context and motivated by the lack of information about grindability of this alloy, this work evaluates the influence of the several grinding parameters on surface integrity, grinding forces (Ft and Fn) and specific grinding energy of nickel-based, Inconel 625 alloy. A fractional factorial design of experiments (DOE) was adopted to use the wheel speed, work speed, depth of cut, abrasive mesh and grinding direction (up and down grinding) as measures of variation in the grinding process. Surface integrity was assessed in terms of surface roughness (Ra and Rz), observations of SEM images and microhardness. The results showed that Inconel 625 is highly susceptible to work hardening during grinding. The grinding wheel speed (vs) was the parameter of greatest effect and the best results were obtained when vs=15 m/s.