Experimental and numerical investigation of laser hot wire welding

With respect to autogenous laser welding, laser welding assisted by a hot wire was capable of saving the consumption of laser power, tailoring the mechanical and physical properties of welds, and improving the gap-bridging capability. In this work, the influences of welding parameters were investigated to combine the positive aspects of laser beam and hot wire. Sound welds were obtained when the laser beam was focused inside the samples. The welding direction had a significant effect on the gap-bridging capability, while the offset distance between the laser focal spot and hot wire tip determined the stability of the feeding of the hot wire into the molten pool. The effect of hot wire on the temperature field and thermally induced residual stress of laser welding was investigated by using the finite element method. X-ray diffraction technique was used to measure the residual stress at the obtained weld beads, and a good agreement between the experimental and numerical results was achieved. Results showed that the transverse and longitudinal stresses prevailed in the laser hot wire welding process, and the thermal stress concentration occurred in the weld pool. When the hot wire voltage was lowered, the residual stresses, especially the transverse residual stress, were markedly reduced.