Welding process stability in narrow-gap oscillating laser-MIG hybrid welding of titanium alloys with various oscillating patterns

• Published in: Journal of manufacturing processes 2025-01, Vol.133, p.151-162
• Main Authors: Cai, Chuang, Yu, Jie, Chen, Zilin, Li, Zhenxin, Chen, Hui, Tang, Ping, Xiong, Fashuai
• Format: Article
• Language: English
• Subjects: Laser oscillating pattern; Narrow-gap oscillating laser-MIG hybrid welding; Titanium alloys; Welding stability
• ISSN: 1526-6125
• DOI: 10.1016/j.jmapro.2024.11.036

Revealing the mechanism of laser oscillating patterns on the laser-MIG hybrid welding process stability was of great significance for improving weld formation and controlling porosity defect of titanium alloys. Convex welds were formed with poor surface formation using linear, 8-shaped and infinity oscillating laser. A circular oscillating laser with more uniform energy distribution favored the formation of concave weld. Weld porosity decreased by approximately 60 % when compared to laser with linear oscillating pattern. A keyhole with the maximum opening size was formed and fluctuated slightly. More laser-induced plasma (LIP) was ejected from the keyhole, which favored the enhancement of electric channel. Particle exchange between the arc and LIP was enhanced. Additionally, the arc burnt stably. The wire melting was accelerated to form smaller droplets, and the droplet transfer frequency increased by about 9.2 % compared with that via linear oscillating laser. Furthermore, the droplet impact force decreased by about 27.3 %. The liquid ridge (LR), formed by the droplet impact, was cushioned by the circular flow of molten metal. The droplet disturbance impact on keyhole wall was suppressed. Besides, when laser oscillated with circle pattern, the liquid metal was sufficiently diffused to rear part of molten pool, thereby suppressing convex welds.