Abstract:The restraint effects of pulse frequency and pulse duty cycle on the precipitates of harmful needle like Al₄C₃ phase were studied in CO₂ impulsed laser welding through the experiment on the SiC_p/6063 composite, and the microstructures of the weld under the different process parameters (pulse time from 1ms to 20ms,duty cycle from 50% to 91%) were analyzed. In order to compare, CO₂ continuous laser was conducted under the same efficiency. The results demonstrate that the proper laser pulse frequency and duty cycle can restrain the formation of Al₄C₃ effectively. However, the burning loss of SiC is more serious and the fluidity of molten pool is less in continuous laser welding than in impulsed laser welding.

Key words:  laser beam welding; microstructure; aluminum metal matrix composites