A study of thick plate ultra-narrow-gap multi-pass multi-layer laser welding technology combined with laser cleaning

In the present paper, the application of laser cleaning technology in thick plate ultra-narrow gap multi-pass multi-layer laser non-autogenous welding process was described. The comparison between weld cross sections and the amount of oxide on the weld surface before and after welding tested by environmental scanning electron microscopy (ESEM) proved the laser cleaning method does play an important role in cleaning the weld. The influence rule of some cleaning parameters to welded joints, including groove angle, laser power, defocusing amount, and cleaning speed, was studied, and the welding defects decreased obviously with the optimal cleaning parameters. Combining this cleaning technology and the laser non-autogenous welding system comprised of the laser autogenous welding, laser wire filling welding, and the laser arc hybrid welding, a 40-mm-thick plate was welded well using a 4-kW fiber laser.