Machining of Inconel 718 with a defined geometry tool or by electrical discharge machining

Inconel 718 alloy is the most used nickel-based superalloy owing to its characteristics of excellent mechanical and chemical properties at high temperatures and relatively low cost in comparison with other alloys. Nevertheless, the mechanical properties and components with intricate geometric shapes usually lead to difficulty in machining this alloy. This article reports a literature review on the machining performance of Inconel 718 alloy using conventional machining processes as well as electrical discharge machining. Based on the literature review, it is possible to highlight that for conventional machining, non-uniform flank wear and notch at the depth of cut are the leading causes for cutting tool failure when machining Inconel 718. Abrasion is the prominent wear mechanism, followed by diffusion, adhesion, and chipping. Regarding the assessed literature, 65 % used cemented carbide as cutting tool material, 20% used ceramic cutting tools, and 15% applied CBN tools. For ED-machining, copper is the most used material as a tool electrode, followed by brass and graphite. Regarding the electrical variables, discharge currents applied are from 10 to 20 A, and the pulse duration varies from 50 to 200 µs. The thickness of the white layer, varying from 3 to 50 μm, depends directly on the combination of process parameters, which involves the variation of discharge current and pulse duration.