Microstructural, mechanical and corrosion properties of handheld laser-welded Inconel 625 joints: a comparison between autogenous welding and ERNiCrMo-3 filler wire addition

This study investigates the microstructural, mechanical, and corrosion properties of Inconel 625 alloy joints produced by fiber laser welding, both autogenously and with ERNiCrMo-3 filler metal. Macrostructural analysis confirmed defect-free welds with increased weld metal volume in filler-added joints. Autogenous welding yielded finer grain structure, but higher concentrations of brittle Laves phase precipitates, leading to increased hardness yet reduced ductility and early crack initiation. Conversely, filler metal welds exhibited coarser grains, lower Laves phase formation, and superior tensile strength and elongation. Corrosion testing revealed the base material possessed the highest corrosion resistance, while filler metal welds demonstrated increased corrosion rates attributed to grain coarsening. These findings highlight the critical influence of welding metallurgy on joint performance, indicating that filler metal use enhances mechanical properties at a moderate compromise in corrosion resistance, guiding optimal welding strategies for Inconel 625 applications.