Surface integrity analysis of WEDMed specimen of Inconel 825 superalloy

WEDM has evolved as a well admired technique for machining of difficult to cut materials such as superalloys. WEDM produces intricate shape and profiles of superalloys by thermoelectric erosion process. But as the process is carried out at very high temperature, the formation of heat affected zone, microcracks, recast layer, porosity etc. resulted in decreased surface integrity of machined specimen and becomes a big problem in WEDM. Discharge energy is the most influencing param-eters that affect the surface integrity of WEDmed samples. In this study, Inconel 825, widely used in aerospace industry for making of combustor casing and turbine blades, was machined with WEDM under different discharge energy. The surface topography of the WEDMed specimen was carried cut by using SEM, XRD and EDX techniques. It was observed from the SEM micrograph that the machined surface includes cracks, pockmarks, craters, and pulled out material. The density and sice of craters increase with increase in discharge energy. Surface crack density of 0.0138 μm/μm2 and recast layer thickness of 34.62μm was obtained for the machined sample at high value of discharge energy while at low value surface crack density of 0.0016 μm/μm2 and recast layer thickness of 20.99μm was observed. EDX and XRD analysis of the specimen showed that an ap-preciable amount of elements viz. Fe (Ferrous), Cr (Chromium), Cu (Copper), Ni (Nickel) are mi-grated to the surface of the workpiece at high value of pulse on time