Gas Tungsten Arc Welding with Synchronized Magnetic Oscillation

Abstract

The search for improvements in mechanized/automated welding techniques has been intense due to skilled labour shortage. In this line, the combination of operational modes (polarity and/or metal transfer mode) within a process has gained attention, since it expands the adjustability of the arc energy. By combining this feature with arc motion, the arc energy delivered to the workpiece can be optimally distributed. Therefore, this work exploits the synchronization between arc magnetic oscillation and gas tungsten arc welding (GTAW) process to control weld bead formation. A system was devised to control the magnetic oscillation and a welding power source synchronously. Characterization of the synchronized magnetic oscillation was carried out based on highspeed filming and electrical data. The welding process was then synchronized with the magnetic oscillation varying the level of welding current according to the arc timeposition, being the effect on weld bead width considered for analysis. Welding without oscillation and with unsynchronized magnetic oscillation were taken as references. The synchronized magnetic oscillation made possible to achieve larger weld bead width on the side with higher current level and longer lateral stop time and vice versa. This technique might be beneficial to applications where extreme weld bead control is required.

Study of the behavior of the electric arc in pulsed GMAW influenced by magnetic oscillation using shielding gas mixtures with different CO2 content

“…In addition, a relatively small arc deflection may be noticed even during the base period. Although this may be related to a lower magnetic field density during the recorded events, an alternate possible factor is the shorter arc length immediately after restarting [22].…”

“…Larquer et al [22] developed a model considering that the arc deflection is hindered by the plasma jet. This gas jet is caused by the unbalance of magnetic forces in regions of the arc close to the electrode and the base metal and its strength (is) proportional to the arc length and the welding current squared [23].…”

“…This effect may be linked to the aforementioned effect of CO 2 increasing energy losses by arc [18]. • Additionally, as arc deflection is stronger during the base current periods and magnetic deflection tend to be inversely proportional to the welding current [21,22], the tendency to arc elongation can be reduced by increasing the base current value. However, at least, for the conditions used in the present study, the CO 2 content in the shielding mixture was the most determinant factor to the process stability.…”

The Impact of EMS on the Temperature Fluctuations, Appearance, and Microstructure of GTA Stainless Steel Welds

“…The reduction of segregation and pores, as well as the grain refinement in the weld, are the additional benefits of EMS [4,6,9,14,32,33]. The author's previous study [8] showed that EMS could make the grain boundaries less tortuous and the transformed austenite smaller in the HAZs.…”

“…The welding parameters employed could alter the microstructure-related properties such as the mechanical properites and corrosion resistance of welds [3]. Consequently, electromagnetic force in various forms has been applied to stabilize welding arcs and reduce welding defects, as a means to improve the quality of the welds by gas tungsten arc welding (GTAW) and plasma arc welding (PAW) processes [2,[4][5][6]. The mechanical properties and corrosion resistance of weldments were improved as well [5,[7][8][9][10].…”