Effects of circular oscillating laser on microstructure and mechanical property of nickel-based superalloy by laser melting deposition

•A laser melting deposition technology with circular oscillating laser beam was proposed, and the multilayer deposition layer of GH3536 nickel-based superalloy was successfully fabricated.•Compared with Gaussian distribution laser, the dilution ratio and heat affected zone of circular oscillating laser are smaller.•Increasing the oscillating frequency of the laser beam can reduce the grain size of the deposited layer and promote the transformation from columnar dendrite to equiaxed crystal.•The GH3536 alloy coating deposited by circular oscillating laser has higher solid solubility, and the volume fraction and size of Laves phase are reduced.•The GH3536 alloy deposited by the oscillating laser has stronger toughness and smaller difference in mechanical properties in the vertical and horizontal directions. GH3536 nickel-based superalloy was fabricated by circular oscillating laser melting deposition and traditional Gaussian laser melting deposition in the present investigation. The effects of circular oscillating laser beam on the macro morphology, microstructure evolution and mechanical properties of the GH3536 alloy were studied. The results show that the dilution ratio and heat affected zone of circular oscillating laser are smaller than those of Gaussian laser. The oscillating laser beam drives the melt flow, destroys the growth of columnar dendrites, promotes the diffusion of elements and inhibits the precipitation of Laves phase. The volume fraction of Laves phase is about 30.03% lower than that of Gaussian laser. Increasing the oscillating frequency or amplitude can refine the grain. The ultimate tensile strength of GH3536 alloy deposited by circular oscillating laser in parallel and vertical directions is 683.64 ± 17.02 MPa and 687.23 ± 5.89 MPa respectively, which is 6.57% and 9.96% lower than that of Gaussian laser, respectively; The elongation in parallel and vertical directions is 35.86% and 38.1%, which is 91.36% and 41.22% higher than that of Gaussian laser, respectively. The circular oscillating laser can significantly improve the toughness of GH3536 alloy and improve the difference of mechanical properties in different sampling directions.