Influence of low-pulsed frequency on arc profile and weld formation characteristics in double-pulsed VPTIG welding of aluminium alloys

Abstract

AA2219 aluminium alloy plates were processed by double pulsed variable polarity tungsten inert gas (DP-VPTIG) welding, and the influence of low-pulsed frequency on arc profile, weld appearance and penetration characteristics were investigated. An image processing algorithm was proposed for arc edge extraction and arc feature sizes acquisition. The arc energy equations in low-frequency pulse peak stage (tp) and base stage (tb) were established based on the electrical parameters. The arc profile periodically expanded in tp and shrunk in tb, resulted from the difference in arc energy of the two stages. The pulsation effects in arc profile, weld appearance and penetration, caused by the pulsed arc were observed to exhibit a decreasing trend with the increase of low-pulsed frequency (fL). The pulsation effects were obvious when fL was 0.5 Hz, then became weak and tended to disappear as fL increased above 3 Hz. The empirical correlations between fL and the pulsation effects of arc profile, weld appearance and penetration were respectively developed. It is recommended to use fL in the range of 1-2 Hz to properly exert the low-frequency pulsation effect. The results provide a valuable basis for controlling and optimizing the DP-VPTIG process in the high efficiency welding of aluminum alloys.

Characterization of pulsed-tungsten inert gas (PTIG) welding on AA5754-H111 alloy: mechanical properties and microstructural analysis

“…With increasing low-pulsed frequency (fL), pulsed arc pulsation effects on arc profile, weld appearance, and penetration decreased. Pulsation effects were prominent at 0.5 Hz but less reliable and perished above 3 Hz [33]. It was found that base metal samples had greater mechanical properties than welded ones.…”

Mechanisms of Gravitational Influence on Weld Pool Behavior and Weld Bead Performance in Variable Polarity Plasma Arc Welding across Different Welding Position

“…Variable polarity plasma arc (VPPA) welding gained widespread application in the field of aluminum alloy structural connections due to its cathode cleaning effect and concentrated arc energy characteristics [1][2][3][4][5][6]. Compared to traditional arc welding techniques, VPPA welding, with its unique keyhole welding mode, effectively eliminates porosity, resulting in superior welding quality and properties of welding bead [7].…”