Effect of Oscillating Amplitude on Microstructure and Mechanical Property of Laser Welding of Dissimilar Stainless Steel

The development of oscillating laser beam welding (OLBW) provides an opportunity to improve the weld formation of dissimilar stainless steels. In this paper, the influence of oscillating amplitude on the weld formation, microstructure, and mechanical properties of dissimilar 430/5Cr15MoV stainless steel was studied. The results showed that the weld morphology became smooth and uniform with an increase in the oscillating amplitude, and there was no obvious defect on the surface. The formation mechanism of weld overflow defects on the weld surface was discussed. The width of the weld metal increased with an increase in oscillation amplitude. The influence of beam oscillation on the microstructure of the weld center was significant, i.e., the proportion of equiaxed grains in the center of the welds increased as the oscillation amplitude increased. The maximum microhardness of the weld was obtained at an amplitude of 1.5 mm. Moreover, the tensile strength of the welds reached 477 MPa, which was comparable to the tensile strength of the 430 stainless steel base material. The fracture modes of all welds were typical ductile fractures, which suggests that the oscillation amplitude had a minor effect on the fracture mechanism of the welds. This study provided a new approach to welding dissimilar stainless steels and offers guidance for the selection of an optimum oscillation amplitude.