Numerical and experimental study of the effect of side assisting gas during laser welding

The influences of side assisting gas flow conditions on the behaviour of laser induced plasma during laser welding process were studied using a two-dimensional model assuming compressible flow. The distributions of temperature, velocity and static pressure within plasma plume under different side gas flow conditions were calculated. The dynamic behaviour of the induced plasma in laser welding process was recorded with the aid of high-speed imaging. The results show that the side assisting gas flow conditions, such as side nozzle height, side assisting gas flow rate and the side nozzle inclination angle, can significantly affect the plasma plume characteristic, the coupling of laser energy into the workpiece and the resultant weld geometry. Modelling results concerning the influences of side assisting gas on plasma characteristics are reasonably consistent with experiment results.