CHARACTER OF MELTING AND EVAPORATION IN LASER-BEAM WELDING OF 2 ALUMINUM-ALLOYS

The phenomenon of evaporation within the keyhole during laser beam wel ding of aluminum Alloys A5052 and A5083 was investigated under differe nt welding conditions. The character of the molten pool was compared a nd analyzed. It was found that the evaporation of the main alloying el ement for these alloys, magnesium, greatly influenced the reaction for ce induced between the metal vapor and thermal plasma, which in turn a ffected the degree of penetration. The results of these experiments al so confirmed that increasing shielding gas flow rate, within a limit, and a slight increase in the entrance angle of the laser beam improved meltability and increased penetration depth. Surface preparation was also observed to improve beam absorption and increase penetration.