This study was conducted to investigate the effect of Electron Beam Welding parameters on the weld quality of thick rolled Inconel 718 plate and to optimize the same. A full-factorial experiment having nine heat inputs (three different levels of welding speed and beam current) was designed. The weld quality was characterized based on weld geometry, microhardness, and mechanical properties. The transverse section of a weld bead when observed under a high magnification microscope showed a typical nail-head-shaped fusion zone. Scanning Electron Microscopy with Energy Dispersive Spectroscopy was performed on fractured surfaces to analyze the material composition and inclusion defects. The fusion area and weld penetration depth were found to be directly proportional to the heat input. At the lowest heat input, the microhardness measurements at the beam entrance showed a softer and wider weld zone compared to the weld-bottom regions. The hardness values increased and became uniform at different weld depths post-heat treatment. Keyhole defects at the highest beam power can be removed by a suitable machining process post welding. All samples but one had tensile strength exceeding the specification for as-received rolled IN718; ductility of welded specimens also met the specification when welded with low heat input. At lower heat inputs, the welded samples fractured outside of the weld zone showing ductile fracture characteristics and indicated their exceptional weld strengths. These results provided a benchmark for comparison with a parallel study on Electron Beam Welding of Selective Laser Melted Inconel 718.
