Investigation on microstructure and texture evolution of linear friction welded IN718 superalloy joints

Linear friction welding tests under different process parameters were performed on IN718 Ni-based superalloy. The microstructure and texture of the joint was characterized by using OM, SEM and EBSD. The results show that a better joint could be obtained with the parameters of friction pressure of 169MPa, amplitude of 3mm, frequency of 35Hz and friction time of 6s, but oxides and carbides are still presented in the root of the flash. The δ phase in the weld zone has been completely dissolved, just with a small amount of NbN, while the δ phase in the heat-affected zone has been partly dissolved with some liquefied grain boundaries, which results in the formation of Laves phase. The full dynamic recrystallization occurs in the weld zone with the fine equiaxed grains, and a shear texture C was formed under the shear stress, while partial dynamic recrystallization occurs in the thermomechanically affected zone, which induced the formation of texture of (335)[I86].