Induction-assisted laser welding of IN-738 nickel–base superalloy

Induction-assisted laser welding was performed with filler metal additions to weld IN-738, a nickel–base superalloy. IN-738 powder was added through a coaxial nozzle to the weld pool in order to reduce the weld defects, such as underfill and porosity in the welds. This was particularly important for the square-groove butt joints due to the presence and opening of gaps in the welding process. Crack-free laser welds were obtained by induction preheating at approximately 800 °C, however, some scattered pores were still observed in the welded specimen. Tensile testing indicated that the strength of the weld metal was comparable to that of the base metal at 850 °C. Stress-induced precipitation of fine γ′ particles was also observed on IN-738 specimens subjected to tensile loading. The preliminary results of this study demonstrated that the quality and performance of laser-welded IN-738 specimens were acceptable. However, more works on the process optimization are required to further improve the weld quality.