Effect of assist gas flow on the gas shielding during laser deep penetration welding

Gas shielding is very important for the titanium alloys in the laser deep penetration welding. The laser keyhole during welding Ti-6Al-4V is simulated initially based control volume method using a combination volumetric heat source. Then, the equations of species, mass, momentum and energy are solved. Important differences have been observed between Ar gas shield and He gas shield. All these experiments have also been simulated using the 3D hydrodynamic software FLUENT. It has been seen that the characteristic size of argon gas shield is larger than that of helium gas shield, that the smaller the nozzle inclination angle, the larger characteristic shield size of the assist gas will be. The effective protection zone will be increased when the flux rate of the nozzle assist gas is increased. Finally, weld cross-sections and plasma plume images at different assist gas rates are experimented. (c) 2006 Elsevier B.V. All rights reserved.