Research on molten pool flow characteristic in all-position LP-LMH welding

Abstract

ABSTRACTThe flow characteristics of keyhole and molten pool impact the real-time process stability and seam formation severely in all-position low-power laser MAG hybrid (LP-LMH) welding. To probe into the molten pool’s real-time dynamics at various spatial welding positions, the high-speed camera images of metal transfer and molten pool were sensed. Meanwhile, a novel spatial flow model of molten pool was developed, and the functions of spatial position and gravity on the molten pool flow were investigated. The results proved that as the spatial position increases, the location of where droplet striking molten pool changes accordingly, further disturbing the keyhole’s stability. Meanwhile, the spatial position seriously affects the molten pool’s flow. The driving forces of molten pool flow at various spatial welding positions are basically the same, and gravity affects the overall movement of molten pool, thereby affecting the vortexes and heat transmission inside the molten pool, as reflected in weld penetration.