Feasibility study of advanced manufacturing processes: Integrating LPBF and LMD for Inconel 718

Abstract

Laser hybrid manufacturing combines Laser Powder Bed Fusion (LPBF) and Laser Melt Deposition (LMD) to overcome LPBF's size constraints and LMD's lower geometric precision. This study explores the feasibility of hybrid LPBF-LMD processing for Inconel 718, focusing on interface properties and mechanical performance. Hybrid samples were first fabricated using LPBF, followed by LMD, with LMD process parameters optimized using a second-order parabolic model. Two LPBF variants as-built and solution-annealed were evaluated to assess their influence on interface characteristics. Microstructural analysis revealed a fine-grained LPBF region and a coarser LMD region with distinct texture, both demonstrating defect-free metallurgical bonding. Microhardness measurements showed a gradient at the LPBF interface, increasing from 346 ± 20 HV at the build plate to 410 ± 18 HV, influenced by solidification and thermal gradients. The LMD region exhibited a lower hardness of 314 ± 12 HV, correlating with its coarser microstructure. Tensile tests showed that as-built LPBF-LMD samples had higher elongation (26.76 ± 2 %) compared to solution-annealed samples (8.29 ± 2 %), with the LPBF region contributing more to ductility. These findings provide key insights into optimizing hybrid LPBF-LMD processing for high-performance components, enabling improved repair strategies and multifunctional part design in aerospace, energy, and other critical applications.