Effect of plasma welding current on heat source penetration ability of plasma-GMAW hybrid welding

Abstract

In the plasma-gas metal arc welding (GMAW) hybrid welding of aluminum alloy, the weld penetration under different plasma welding currents was compared. When the plasma welding current was lower than 150 A, the hybrid welding penetration was greater than the sum of the single plasma welding and the single GMAW penetration. When the plasma welding current reached 130 A, with the increase of the plasma welding current, the advantage of the weld penetration of the hybrid welding was gradually weakened compared with that of the single welding. The above change mechanism is revealed from the perspectives of heat source energy distribution and molten pool stress. The results show that when the plasma welding current is lower than 110 A, the area of the high-temperature region in the arc zone of GMAW in the hybrid welding increases compared with that in the single GMAW. The trend of arc energy transfer to the penetration direction increases under the action of arc pressure, arc shear force, electromagnetic force, and droplet impact. With the increase of plasma welding current, the hightemperature area of the GMAW arc rst increases and then decreases. When the plasma current reaches 130 A, the effect of arc pressure, arc shear force, electromagnetic force, and droplet impact on increasing the penetration begins to weaken.1 Introduction gas metal arc welding (GMAW) is widely used in aluminum alloy welding because of its easy automation and high production e ciency [1,2]. When welding thick-plated high-strength aluminum alloys using GMAW process, the weld requires multilayer welding because the GMAW arc energy is not concentrated. However, high heat input will lead to a series of welding problems, such as coarse grain, crack and so on, which will reduce the mechanical properties of welded joints [3]. In order to solve the above problems, the high energy beam was combined with GMAW to increase the penetration and reduce the welding heat input. The most common is laser -GMAW hybrid welding and plasma -GMAW hybrid welding. For laser-GMAW hybrid welding, aluminum alloy has a strong re ection on laser, and plasma absorbs laser energy, which reduces laser e ciency. Moreover, due to the high welding speed, pores are easily formed [4].Plasma-GMAW hybrid welding can effectively avoid the above problems.According to the relative position of the heat source space, plasma-GMAW hybrid welding is divided into coaxial and paraxial. In 1972, Essers et al. [5] in Philips Research Laboratories rstly introduced the coaxial plasma-GMAW process. The wire is surrounded by double arcs and the number of melting coating increases [6][7][8]. However, due to the plasma arc surrounding the GMAW arc, the plasma arc compression effect decreases. Nonetheless, given the coaxial welding torch structure and the coupling effects between the plasma and GMAW arc [9, 10], the arc divergence has the effect of reducing the speed of the droplets arriving at the weld pool [11,12]. Divergence of plasma arc and reduction of droplet momentum are unfavorable to weld p...

A Review of Numerical Simulation of Laser–Arc Hybrid Welding

“…In LAHW, welding parameters (such as laser power, arc current, and wire spacing), heat source parameters, and process parameters (such as shielding gas flow rate and welding speed) have great influence on laser-arc interaction, and help to achieve the control of weld formation, welding process stability, and welding defects and other purposes [55][56][57]. Gas hole defect is the key research object of welding-related subjects because it can reduce the effective working section of the weld seam, lead to stress concentration, and then reduce the mechanical properties of the weld seam.…”