Influence of cusp external magnetic field on deposition rate of two-electrode TIG welding

Abstract

Experiments have been conducted to investigate the influence of the cusp external magnetic field (EMF) on deposition rate of two-electrode tungsten insert gas (T-TIG) welding.T-TIG arc parameters such as arc shape, arc voltage, arc pressure and arc plasma information were acquired respectively. Results showed compared to TIG, a higher welding current could be allowed for T-TIG, due to its low arc pressure characteristic. Under the effect of the cusp EMF, the arc shape was compressed along x-axis of T-TIG, while elongated along y-axis of T-TIG. Besides, the peak arc pressure of T-TIG was not significantly increased by the cusp EMF.Moreover, with the action of the cusp EMF, the maximum values of the electron temperature (Te) and electron density (Ne) of T-TIG were not significantly increased, but along y-axis, the increments of the two parameters were gradually increased and their distributions were widened. Therefore, more arc energy was allocated on y-axis of T-TIG by the cusp EMF, which could improve the preheating and the melting of the filler wire along y-axis, so the deposition rate of T-TIG could be increased by 17.6% under the effect of the cusp EMF.

Effects of Magnetic Fields in Arc Welding, Laser Welding, and Resistance Spot Welding: A Review

“…Interestingly, this phenomenon still exists for two-electrode TIG (T-TIG) welding. [28,83] To explore the arc characteristics of T-TIG under the CMF, a serious studies was conducted by Liu et al [28,83] With the help of high-speed camera and spectrograph, the arc morphologies of T-TIG under different excitation currents are shown in Figure 7.…”

“…To explore the arc characteristics of T‐TIG under the CMF, a serious studies was conducted by Liu et al [ 28,83 ] With the help of high‐speed camera and spectrograph, the arc morphologies of T‐TIG under different excitation currents are shown in Figure . Two arcs emitting from the tungsten electrode can couple into a larger arc due to self‐induced Lorentz force.…”

“…When a filler wire was feeding, the melting efficiency along the long axis of arc can be improved by 17.6%. [ 28 ] However, due to the structure of CMF, the molten pool is subjected to a very small Lorentz force. Thus, the microstructure barely changed after applying the CMF.…”

“…In addition to the conventional uniform magnetic field, there is a kind of cusp magnetic field (CMF), which can change the arc shape from circular to ellipse by applying electromagnetic force and has the ability to improve the penetration ability [27] and deposition rate. [28] Based on the results of the aforementioned researchers, some basic effects of the magnetic field on the arc and the molten pool can be summarized. The magnetic field is classified as static constant magnetic field or alternating magnetic field depending on whether it changes direction.…”

“…In addition to the conventional uniform magnetic field, there is a kind of cusp magnetic field (CMF), which can change the arc shape from circular to ellipse by applying electromagnetic force and has the ability to improve the penetration ability [ 27 ] and deposition rate. [ 28 ]…”