Analysis of Metallic Plume Image Characteristics During High Power Disk Laser Welding

摘要

Metallic plume is an important phenomenon during high power disk laser deep-penetration welding, which can reflect the welding quality. To study this laser-induced plume characteristics and its relation to welding quality, an extraviolet and visible sensitive high speed color camera was used to capture the metallic plumes in a high-power disk laser bead on plate deep-penetration welding of Type 304 austenitic stainless steel plates at a continuous laser power of 10 kW. These captured digital images were firstly processed in RGB color spaces, and then were transferred to the Hue-Saturation-Intensity (HSI) color spaces from the RGB color spaces. The area of metallic plume was segmented and defined as the plume eigenvalue. The fluctuation of weld bead width was used to evaluate the welding stability. To monitor the plume behavior, a short-time Fourier transform was applied to obtain the time-frequency characteristics of plume images. Also, the hierarchical clustering was analyzed for the time-frequency characteristics of plume images. The results of hierarchical clustering showed there existed relationship between the metallic plume area and welding quality, and the fitting curve of clustering could reflect the fluctuation trend of the weld bead width effectively.