Influence and simulation of protective gas on joint morphology and droplet transition

In order to study effect of protective gas flow on morphology and droplet transition of hybrid welding joint, theoretical analysis and experimental verification of laser arc hybrid welding test were carried out by using 5mm thick high strength steel sheet. The morphology of welding seam under different gas flow, arc and droplet image during the welding process were obtained. The results show that the welding depth first increases and then decreases with the increase of shelding gas flow. The welding depth reaches the maximum with shelding gas flow of 25L/min. The welding seams have good spreading and less splash. Shelding gas flow affects droplet transition frequency by affecting droplet transition form. Droplet transition frequency reduces with the increase of shelding gas flow. Droplet transition frequency is stable with shelding gas flow of 25L/min. FLUENT software was used to simulate gas flow. The larger the gas flow, the greater the shelding gas flow rate, the smaller the action area on the workpiece surface. The results lay the foundation for the preparation of high quality welding seam with shelding gas flow in practical engineering.