Effects of Beam Shape on the Microstructures and Mechanical Properties during Thin-Foil Laser Welding

In this study, a fiber laser at a wavelength of 1070 nm with different beam shapes (spot, dough-nut, and spot-wobble) was used to weld thin 316 L stainless steel foils. The welding speed was varied from 400 to 1000 mm/s in the absence of shielding gas. The weld geometry, microstructure, lap shear strength, and crystallographic grain structure of the micro-joints were analyzed and correlated with the beam shape and welding speed. The results indicate that the laser beam shape significantly affected the weld width and penetration depth, and the best welding speed was 500 mm/s. This study proved for the first time that a spot-wobble laser beam could achieve better mechanical properties and microstructural characteristics than a doughnut beam during the high-power laser welding of thin-foil stainless steel plates.

Automated summary

In this study, a fiber laser with a wavelength of 1070 nm was used to weld thin 316 L stainless steel foils using different beam shapes. The effects of beam shape and welding speed on the weld geometry, microstructure, lap shear strength, and crystallographic grain structure were analyzed. The results showed that the laser beam shape significantly influenced the weld characteristics, and the spot-wobble beam at a welding speed of 500 mm/s achieved the best results. This study demonstrated the superiority of the spot-wobble beam over the doughnut beam in high-power laser welding of thin-foil stainless steel plates.