Electron beam welding of rolled and laser powder bed fused Inconel 718

This paper explores the feasibility of welding Inconel 718 (IN718) and compares the quality of electron beam welded samples produced by hot rolling and laser powder bed fusing (L-PBF). Electron beam heat input, varying in the range 175-300 J/mm, was the main parameter in welding. Microhardness, tensile properties, and fractography study using both optical and scanning electron microscopy were employed to analyze and compare the quality of the welded samples. Energy-dispersive X-ray analysis was used to identify chemical compositions of different phases on the fractured surfaces. Large voids were observed at high heat inputs (>= 213 J/mm). Excellent weld penetration was obtained and was proportional to the beam heat input. Both yield and tensile strength of the welded L-PBF materials exceeded those of rolled materials and met the minimum requirement from ASTM specification; however, the ductility of welded L-PBF material did not. The brittleness of these L-PBF materials came from the brittle Laves phase and Al-Ti-O compounds in the microstructure and non-optimal L-PBF parameters. These drawbacks can be further reduced by adjusting the L-PBF parameters and suitable post-processing techniques before electron beam welding.