Defects inhibition and process optimization for thick plates laser welding with filler wire

One of the challenges in laser welding of thick plates is the formation of lack of fusion defects. In this paper, it is found that the formation of such defects has relations with the surface profile of the weld joint. Experiment results indicate that the weld joints can form perfect fusion when the surface of solidified filling metals is concave. Then the author studied the relations between input welding parameters and single bead geometry, which can affect the surface shape of solidified metals, filling passes and defects formations during the multi-pass laser welding process. Further investigations and analysis show that P/Vf (the radio of laser power to wire feed rate) and Vf/Vw (the radio of wire feed rate to welding speed) can be used to quantify the input variables and impede the formation of lack of fusion defects. Verification results show that the optimized parameters for perfect fusion are: P/Vf  > 1.5 and Vf/Vw < 6.