Experimental investigations on WEDM performance characteristics of FGH99 powder metallurgy superalloy

Abstract

In response to challenges posed by conventional machining methods, an exploratory experimental investigation was conducted to assess the effectiveness of wire electric discharge machining (WEDM) in fabricating turbine disc slots from powder metallurgy superalloy FGH99. The present study conducted a single-factor experiment on WEDM using FGH99 alloys, with the aim of investigating the impact of different WEDM parameters on the material removal rate, surface roughness, and surface morphology. Additionally, the analysis encompassed the characterization of both the heat-affected zone and plastic deformation zone on the workpiece surface. Results show that there is a positive correlation between surface roughness and variables such as pulse width, pulse gap, servo voltage, and wire tension. Conversely, wire speed exhibits an inverse relationship with surface roughness. Notably, the impact of pulse width on surface roughness surpasses that of other parameters. Metallographic examination reveals that under the selected process parameters, while ensuring the efficiency of material removal, superior machining quality was achieved. The absence of conspicuous recast layers on the workpiece surface, with an average thickness of the plastic deformation layer measured at 3.97 µm, indicating favorable processing outcomes. The aforementioned findings provide valuable experimental insights into the WEDM process of FGH99 alloys and offer foundational engineering data for the fabrication of turbine disc slots made from this material.