A study of welding process in connecting borosilicate glass by picosecond laser pulses based on response surface methodology

Picosecond laser welding process was investigated on connecting borosilicate glass. A three-factor with five-level central composite rotatable design was utilized in the experimental study. The response surface methodology (RSM) was used to optimize the key process parameters which determined the weld quality, which includes laser power, welding speed and repetition frequency. The micro-hardness, surface microscopic morphologies and weld width were also characterized respectively. Energy dispersive spectrometer (EDS) line scans were performed to analyze the diffusion and migration of network formers elements during the laser welding process. The lap-shear strength of welded joints was determined by an electronic universal testing machine. The results indicated that the weld seam was continuous and uniform by using optimized process parameters with the lapshear strength ranging from 3.25 to 6.92 MPa and the weld width ranging from 250.9 to 430.8 mu m. The diffusion of Si and O elements occurred during the laser welding process, which was also one of the reasons for the improvement of the micro-hardness of the welded zone. The established mathematical model can precisely reflect the interactive influence of the picosecond laser welding process parameters on the lap-shear strength and weld width. Furthermore, the optimized prediction results were consistent with test results.