Effect of variable laser incident angles on microstructure and mechanical properties of laser-cladded Inconel 718

In the laser cladding process of complex components, laser deflection is a significant issue that greatly affects manufacturing quality. This study investigates the influence of different incident angles on the microstructure and wear resistance of laser-clad layers. Firstly, an Inconel 718 coating was prepared on an Inconel 718 substrate using an IPG fiber laser. Next, the macrostructure and microstructure of the coating were observed using electron microscopy. Finally, the microhardness of the coating was measured, and the underlying mechanisms affecting wear resistance due to incident angle were revealed. The results show that with an increase in the laser incident angle, the laser energy distribution becomes more divergent, leading to a shift in the peak energy density and changes in the macroscopic morphology of the melt pool, exhibiting a non-Gaussian distribution and resulting in increased cellular dendrite count and coarsened grains. Laser deflection causes variations in microstructure and properties between inner and external angles, where higher laser energy density and temperature gradients at the inner angle result in finer grains and more numerous smaller secondary dendrites on the dendritic arms, along with less severe element segregation and higher microhardness at the inner angle.