振镜扫描激光微焊接是激光微焊接的发展方向。采用基模光纤激光器及振镜系统对厚度为100 μm的AISI304不锈钢箔进行平板扫描焊接,对比研究了氩气保护与无气体保护时的激光微焊接工艺,建立了两种条件下激光微焊接的工艺窗口。结果表明:无气体保护时,激光微焊接会产生不稳定过渡区,其产生机理不是热导焊接模式和深熔焊接模式的交替出现,而是氧化导致的深熔焊接过程不稳定;气体保护可以避免不稳定过渡区的产生,并扩大焊接工艺窗口。

Laser-micro-welding based on galvanometer scanning has attracted great interest. Herein, bead-on-plate scanning micro-welding of 100-μm-thick AISI304 stainless steel foil is conducted by using a single-mode fiber laser equipped with a galvanometer scanning system. A comparative study is conducted on the laser-micro-welding processes with/without Ar-gas protection, and process windows of laser-micro-welding for the both conditions are established. Results show that an unstable transition zone exists during laser-micro-welding without gas shielding. The unstable transition zone is generated during the deep penetration welding mode alone, rather than during the alternation of thermal conductivity welding mode and deep penetration welding mode, as reported previously. The oxidation during laser-micro-welding results in an unstable deep penetration welding mode, during which a transition zone is formed. Furthermore, by applying gas shielding, we find that the unstable transition zone is eliminated, and the welding-process window is expanded.