Abstract
Tandem-pulsed gas metal arc welding (TP-GMAW) simultaneously uses two wire-electrodes to enhance the material deposition rate, leading to the generation of a finger-shaped penetration as one of the arcs penetrates deeper than the other. On the other hand, workpiece vibration is one of the techniques used to control the microstructure of weld metal and a heat-affected zone. It is incidentally found that a specific vibration condition changes the finger-shaped penetration into pan-bottom shaped penetration in the TP-GMAW even though the vibration energy is much lower than the arc energy. Microstructure observation and elemental analysis are carried out for the welds fabricated without vibration and with three kinds of vibration modes, namely sine, random, and shock. The specific sine-mode vibration exhibits pan-bottom. The other modes of vibration in the same welding conditions exhibited invariable finger-shaped penetration. The Si atoms as a tracer distribute uniformly in the sine-mode. However, Si atoms segregate at the bottom of the finger-shaped weld metal with the random-mode and shock-mode workpiece vibrations. The weld pool shape change is prominent at a specific frequency. A resonance phenomenon between the droplet flow pattern and the molten material flow in the weld pool is likely to play a vital role in the change.
Highlights
Vibration-assisted welding (VAW) is known as a successful replacement of post-weld treatments of arc welds
The present study aims to investigate the shape change phenomenon along with the metallurgical aspects of change in vibration frequency, acceleration, welding speed, and time of workpiece vibrations considering different vibration modes
The article presents an experimental study on effect of vibration on weld pool formation in tandem pulse gas metal arc welding
Summary
Vibration-assisted welding (VAW) is known as a successful replacement of post-weld treatments of arc welds. Many benefits of vibration effect on the performance of the welds have been reported over the past decades. Morphology modification, and reducing residual stresses are advantages that lead to improving mechanical properties in the weld zone [1]. The vibration of the arc due to pulsed current leads to agitation in the weld pool. The weld pool oscillation behavior in the case of gas tungsten arc welding (GTAW) has been studied extensively [11,12,13,14] and is likely best understood. The oscillations are triggered by applying an external force on the weld pool such as superimposing a high current pulse on the welding current or mechanical
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