Study on the Back Formation of Root Welding by MAG-TIG Twin-arc Welding in Thick Plate

doi:10.3901/JME.2018.10.078

Abstract

Abstract: Backing welding is a key procedure in thick plate multi-pass welding and has a crucial impact on the performance of weld joints. Due to the low degree of automation and low production efficiency for back welding, among shipbuilding, marine engineering, heavy machinery and other industries, the metal active gas-tungsten inert gas (MAG-TIG) twin-arc tandem root welding process on thick plate with 20 mm is carried out, welding process and weld seam forming mechanism are investigated. Furthermore, arc plasma behaviors and molten pool state are studied during interaction between metal active gas (MAG) arc and tungsten inert gas (TIG) arc plasma. The results indicate that TIG arc has regulation effect on MAG arc heat distribution when arc discharges. Combined with arc plasma behaviors and molten pool state, a result can be found that, when the bead back formation is optimum, TIG arc accelerates the weld pool to flow backwards. Thus the quantity of liquid metal is reduced at the bottom of the molten pool and at the blunt edge of the plate. At this condition, molten pool with balance stress and steady state is obtained, and a sound, uniform and stable surface appearance back weld is acquired.

Key words: high efficient welding, MAG-TIG double arc tandem welding, mild steel thick plate, one-side welding with back formation, root/backing welding

CLC Number:

TG444

ZHOU Yanbin, SHI Jipeng, LIU Liming. Study on the Back Formation of Root Welding by MAG-TIG Twin-arc Welding in Thick Plate[J]. Journal of Mechanical Engineering, 2018, 54(10): 78-84.

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