Fundamental Research On Laser-MIG Hybrid Welding And Its Application

Laser–arc hybrid welding is a new special welding technique in laser processing, in which the laser beam and the arc act on the same molten pool, the synergistic actions of the laser and the arc were exploited, improving the welding efficiency compared with the individual processes.A descriptive term of laser–arc processes should include the laser type(i.e. CO2, Nd:YAG) and the arc welding process(TIG, Plasma, MIG/MAG), and hybrid laser–MIG welding becomes one of the most significant laser welding technologies in industry due to its higher welding efficiency, higher tolerance to gaps between plates, and adjustment of composition and microstrcture of the weld metal.Based on summarization of the current research on hybrid welding technique, a program of experimental work was undertaken to investigate the hybrid laser–MIG welding process and its application in this paper. First a paraxial CO2 laser–MIG hybrid welding system was set up and produced bead–on–plate runs on carbon steel under different welding conditions, the weld bead shape were measured. The results show that the laser–MIG hybrid welding can increase penetration and width, improve the quality of weld bead formation compared with laser and arc welding, and the higher the laser power, the more significant the effect.Then a Nd:YAG laser–MIG hybrid welding system was used to study the relationship between hybrid welding parameters and bead geometry, the parameters like laser power, arc power, welding speed, welding direction etc greatly influenced the weld bead. Influence of interaction between laser and arc energy on bead geometry was analyzed, it was found that under stated condition the weld penetration mainly depends on the laser power and the width depends on the arc power, the reciprocity of laser and arc contributes a positive effect on penetration, but a negative effect on weld width. With a certain constant power of Nd:YAG laser combined with the arc, the weld penetration went deeper at first and then reduced as the arc power increased, when penetration was in peak value, the energy ratio of arc power to hybrid power was about 0.6. Later the advantages of hybrid welding compared with laser or MAG welding alone were assessed, and a series of adaptability experiments of laser–MIG hybrid welding were carried out. The results indicate that the laser–MIG hybrid welding improves welding efficiency and owns good welding adaptability.At last, the application of laser–MIG hybrid welding on ZL114 aluminum alloy was realized on the 2–8mm thick plates and cylinders butt joints.