Adjustable Ring Mode (ARM) laser welding of stainless steels

As a combination of the annular laser beam and gaussian laser beam, adjustable ring mode (ARM) laser is a promising technology for stabilizing laser-based welding process. Process status and fusion efficiency of laser-materials processing was investigated experimentally under different shape of laser modes, including ring laser mode, center laser spot alone, and ring/center dual spots, with welding speeds ranging from 5 to 100 mm/s. The process characteristics of the keyhole entrance, including the area, length, and width were monitored and quantified by a high-speed CCD camera with the selected image processing method. The process intensity of metallic vapor and plasma was further monitored by a spectrometer, and the relationship between plasma intensity and the keyhole entrance geometry was analyzed correspondingly. Additionally, individual effects of shaped laser beam on the geometric characteristics of the fusion zone across the weld cross-sections such as effective depth of penetration, and the area and width of the fusion zone were analyzed accordingly. Experimental results showed that the process variation of the keyhole entrance differ with different welding energy modes, and the main difference came from the variation of keyhole length. The plasma intensity had a positive relationship with the keyhole entrance in different shape of laser beam welding. The fusion efficiency of cross-section was quite different with different laser beams. This work provided a new investigation for researchers and engineers to have a better understanding of shaped laser beam on materials welding.