Mechanism of laser welding for SiCw/6061Al composite

SiCw/6061Al composite was welded by pulse laser welding successfully. The influence of the parameters such as surface treatment state, laser output power, welding speed, protective atmosphere, and pulse frequency on the welding quality was studied. The results show that laser output power and welding speed are the main factors which affect the microstructure and the property of weld, and change of laser pulse frequency has the definite influence on them. However, surface treatment state has little influence on the properties of joint. At the same time, we obtained good effect by using nitrogen gas instead of argon gas. The microstructure of joint was observed and the strength loss of joint was analyzed by SEM and TEM. The main reason for the decrease of the strength of welded joint is that when laser welding was used, SiC whisker reacted with Al to form brittle Al4C3. Therefore, the conception of the critical activity α[Si]min was put forward.