Experimental and Numerical Investigation of Mechanical Properties of Laser-Welded Additively Manufactured Inconel 718

This study investigates the effects of different welding and heat treatment sequences on the mechanical and microstructural properties of laser powder bed fusion (PBF-LB) fabricated Inconel 718. Three conditions were examined: laser welding of as-built material (LW-built), welding after heat treatment (HT-LW), and welding followed by post-weld heat treatment (LW-HT). Tensile testing, microscopy, fractography, and finite element simulations were used to evaluate performance. The LW-HT condition exhibited the highest strength (UTS ~1430 MPa) and the most uniform stress distribution, attributed to the re-precipitation of laves/δ phases during post-weld aging. In contrast, the HT-LW condition showed localized softening and early failure due to precipitate dissolution in the fusion zone. Fracture surface analysis confirmed enhanced ductility in LW-built and refined microstructural features in LW-HT. These findings demonstrate that post-weld heat treatment (LW-HT) is the most effective route for optimizing strength and structural stability in welded PBF-LB Inconel 718, with some trade-off in ductility.