Keyhole dynamic status and spatter behavior during welding of stainless steel with adjustable-ring mode laser beam

A novel adjustable-ring mode laser (ARM) welding of SUS304L stainless steel sheet was investigated in this work. The ARM laser consists of two parts: ring laser beam as outer part; circular laser beam as center part. A Phantom high-speed camera with image processing algorithm was used to monitor the keyhole dynamic behavior. The spatter ejection, molten pool, and keyhole status were observed from the top view position. The characteristics of spatters were monitored from the side position of the camera. Experimental results showed that the pure circular laser beam (regular Gaussian beam) generated a periodic opening and collapsing keyhole with plenty of spatters in the welding process. However, the pure ring laser beam generated a continuously opening keyhole-inlet in the welding process. Because of the ring laser on welding, the dual-mode ring/circular laser (ARM laser) maintained a relatively opening keyhole with a smaller number of spatters comparing to pure circular laser welding. This work provided a full understanding of the process mechanism regarding the welding with shaped laser beam. The adjustable-ring mode laser is expected to be applied in a high-quality industrial manufacturing process.