Analysis of welding process stability and weld quality by droplet transfer and explosion in MAG-laser hybrid welding process

The metallic vapor and molten pool include plenty of welding information in the manufacturing process of MAG (Metal Active Gas Arc Welding)-laser hybrid welding. In this work, double high speed cameras are used to take the real-time images of the top-vapor and bottom-molten pool in the hybrid welding process. In order to monitor welding process status and weld quality, this paper proposes a method which combines the period of droplet transfer and droplet explosion. In time domain, the morphological features include the area of top-vapor, area of spatters, number of spatters and the average gray value of the bottom-molten pool, those features are used to research the stability of short circuiting transfer as well as the mechanism of the welding process. Besides, the welding process stability and weld quality are analyzed by features including the period of droplet transfer and droplet explosion in time and frequency domain. The experimental results show the period of droplet transfer and droplet explosion can effectively reflect welding process and weld quality. It provides a basis for monitoring and controlling MAG-laser hybrid welding process status.