Effects of superposed continuous diode laser on welding characteristics for aluminum alloy in pulsed Nd:YAG laser welding

The efficient welding of aluminum alloy has been strongly required for lightening the electronic products and automobiles, and a pulsed Nd:YAG laser is widely used for its application. However, the low absorption of a Nd:YAG laser makes it difficult to weld the aluminum alloy efficiently. Therefore, a pulsed Nd:YAG laser of 1064nm in wavelength and a continuous diode laser of 808nm in wavelength were spatially superposed, since the absorption rate of the continuous diode laser to the aluminum alloy is much higher than that of a pulsed Nd:YAG laser. The maximum temperature of specimen surface in the vicinity of laser irradiation area increased 50K by the superposition of continuous diode laser and pulsed Nd:YAG laser, and the energy of Nd:YAG laser was absorbed efficiently. Moreover, the thermal analysis indicated that the temperature of specimen surface with the continuous diode laser and the pre-heating pulse could be kept approximately 200K higher than that without these processes. The combination of pre-heating pulse and diode laser made it possible to increase the penetration depth even from the beginning of laser scanning.