Character of Melting and Beam Welding of Two Evaporation in Laser Aluminum Alloys The evaporation of magnesium, the main alloying element for A5052 and A5083 aluminum, influences weld penetration

ABSTRACT. The phenomenon of evaporation within the keyhole during laser beam welding of aluminum Alloys A5052 and A5083 was investigated under different welding conditions. The character of the molten pool was compared and analyzed. It was found that the evaporation of the main alloying element for these alloys, magnesium, greatly influenced the reaction force induced between the metal vapor and thermal plasma, which in turn affected the degree of penetration. The results of these experiments also 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

Experimental investigation of hydrodynamics of melt layer during laser cutting of steel

In laser cutting process, understanding of hydrodynamics of melt layer is significant, because it is an important factor which controls the final quality. In this work, we observed hydrodynamics of melt layer on kerf front in the case of laser cutting of steel with inert gas. The observation shows that the melt flow on the kerf front exhibits strong instability, depending on cutting velocity. In intermediate range of velocity, the flow on the central part of the kerf front is continuous, whereas the flow along the sides is discontinuous. It is firstly confirmed that the instability in the side flow is the cause of the striation initiation from the top part of the kerf. The origin of the instability is discussed in terms of instabilities in thermal dynamics and hydrodynamics. The proposed model shows reasonable agreement with experimental results