Stability and Heat Input Controllability of Two Different Modulations for Double-Pulse MIG Welding

Abstract

Aluminum alloy welding frequently experiences difficulties such as heat input control, poor weld formation, and susceptibility to pore generation. We compared the use of two different modulations for double-pulse metal inert gas (MIG) welding to reduce the heat input required to generate oscillations in the weld pool. The stabilities of rectangular wave-modulated and trapezoidal wave-modulated double-pulse MIG welding (DP-MIG and TP-MIG) were analyzed by examining their welding processes and weld profiles. We found that the transitional pulse in TP-MIG welding results in smoother current transitions, softer welding arc sounds, and a highly uniform fish-scale pattern. Therefore, TP-MIG welding is more stable than DP-MIG welding. The effects of these double-pulse modulation schemes on welding input energy are presented. We propose methods for reducing welding input energy by varying the number of pulses or the pulse base time of low-energy pulse train while keeping the welding current and welding arc stable and unchanged. Compared to DP-MIG welding, TP-MIG welding reduces the input energy by 12% and produces finer grain sizes, which increases weld hardness. Therefore, TP-MIG welding offers a new approach for heat input control in DP-MIG welding of aluminum alloys. The results of this work are significant for aluminum alloy welding.

Comparative Study of Droplet Transfer Modes on Appearance, Microstructure, and Mechanical Properties of Weld during Pulsed GMAW

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Modified Linear Technique for the Controllability and Observability of Robotic Arms

“…T HE concept of controllability denotes the ability to move a robotic arm around in its entire configuration space using only certain admissible manipulations. The exact definition varies slightly within the framework or the kind of applied robotic arms [1], [2], [3]. Controllability and observability are dual aspects of the same problem.…”

Effect of low heat-input double-pulse gas metal arc welding on weld formation and microstructure of 6061 aluminium alloy

“…At present, the current research on DP-GMAW is mainly focuses on the following two aspects: reducing the heat input and increasing the stirring effect of the molten pool. First, the heat input during the welding process can be reduced by using different current waveforms, such as median pulsed current waveform [15], trapezoidal wave-modulated current waveform [16], and gaussian pulsed current waveform [17]. Wu et al [18] introduced a dual-wire DP-GMAW with a median current waveform based on the conventional rectangular pulse and found that changed the median current, the average welding current also changed.…”