Experiment study and regression analysis of molten pool in laser welding

Relationship between welding parameters and molten pool morphology was investigated by experiment analysis. The welding experiments were designed by Taguchi L27 method, while laser power, welding speed and defocusing distance were considered. The periodical change of molten pool had been observed. Defining and extracting the length of the molten pool, the width of the molten pool, the area of the molten pool in one period. The oscillation period of the molten pool also can be obtained. The influence of laser power on molten pool morphology was greater than that of welding speed and defocusing distance. Welding speed play a negative effect on molten pool morphology and oscillation period. Defocusing distance had a complicated effect on molten pool morphology and little effect on oscillation period. Applying statistical analysis, four nonlinear regression equations were established between process parameters and molten pool morphology. Mean relative errors were less than 5%, which mean the predicted value of the regression equations matched well with the actual value.