Comparative study on the weldability and mechanical performance of IN718, ATI 718Plus alloy in laser beam welding

Laser beam welding (LBW) has recently attracted worldwide research attention as a candidate of joining technology for the repair and assembly of aero-engine components. Nickel-based superalloys are the primary structural materials for hot-end components, in the present work, the weld profile, microstructure configuration, and relevant mechanical properties of nickel-based IN718, 718Plus similar/dissimilar LBW joints were comparatively investigated. The single-pass butted LBW on IN718/IN718 thin plates without wire filling obtained a continuously penetrated weld with a wineglass-shaped morphology. In comparison, the implementation of LBW on 718Plus/718Plus faced several challenges that it was difficult to form a continuous and stable weld profile, even when the weld penetration was continuous, the depth-to-width ratio was insufficiently larger to cause an exaggerated weld reinforcement, weld pool collapsing and other issues, the joints with bowl-shaped weld profile showed significantly degraded tensile properties than IN718/IN718 joints. The dissimilar welding of IN718/718Plus was attempted to improve the weldability of 718Plus, which achieved a continuously symmetrical wineglass-shaped weld profile with enhanced depth-to-width ratio, reduced reinforcement and superior tensile properties compared to 718Plus/718Plus joints. The results provide vital data for understanding the weldability of IN718 and 718Plus superalloys, and open a novel thought resolving the problems of 718Plus LBW joints via introducing IN718 as dissimilar weldment.