Effect of Arc Pressure on the Digging Process in Variable Polarity Plasma Arc Welding of A5052P Aluminum Alloy
1
Engineering Research Center of Advanced Manufacturing Technology for Automotive Components, Ministry of Education, Beijing University of Technology, Beijing 100124, China
2
Joint and Welding Research Institute, Osaka University, Osaka 5670047, Japan
3
Beijing Engineering Researching Center of laser Technology, Beijing 100124, China
*
Author to whom correspondence should be addressed.
Materials 2019, 12(7), 1071; https://doi.org/10.3390/ma12071071
Received: 11 March 2019
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Revised: 26 March 2019
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Accepted: 29 March 2019
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Published: 1 April 2019
(This article belongs to the Special Issue Welding, Joining and Coating of Metallic Materials)
The keyhole digging process associated with variable polarity plasma arc (VPPA) welding remains unclear, resulting in poor control of welding stability. The VPPA pressure directly determines the dynamics of the keyhole and weld pool in the digging process. Here, through a high speed camera, high frequency pulsed diode laser light source and X-ray transmission imaging system, we reveal the potential physical phenomenon of a keyhole weld pool. The keyhole depth changes periodically corresponding to the polarity conversion period if the current is same in the electrode negative (EN) phase and electrode positive (EP) phase. There exist three distinct regimes of keyhole and weld pool behavior in the whole digging process, due to the arc pressure attenuation and energy accumulation effect. The pressure in the EP phase is smaller than that of the EN phase, causing the fluctuation of the weld pool free surface. Based on the influence mechanism of energy and momentum transaction, the arc pressure output is balanced by separately adjusting the current in each polarity. Finally, the keyhole fluctuation during the digging process is successfully reduced and welding stability is well controlled.
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Keywords:
VPPA welding; keyhole; digging process; plasma arc pressure; electrode energy balance; X-ray transmission system
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MDPI and ACS Style
Xu, B.; Tashiro, S.; Jiang, F.; Chen, S.; Tanaka, M. Effect of Arc Pressure on the Digging Process in Variable Polarity Plasma Arc Welding of A5052P Aluminum Alloy. Materials 2019, 12, 1071. https://doi.org/10.3390/ma12071071
AMA Style
Xu B, Tashiro S, Jiang F, Chen S, Tanaka M. Effect of Arc Pressure on the Digging Process in Variable Polarity Plasma Arc Welding of A5052P Aluminum Alloy. Materials. 2019; 12(7):1071. https://doi.org/10.3390/ma12071071
Chicago/Turabian StyleXu, Bin, Shinichi Tashiro, Fan Jiang, Shujun Chen, and Manabu Tanaka. 2019. "Effect of Arc Pressure on the Digging Process in Variable Polarity Plasma Arc Welding of A5052P Aluminum Alloy" Materials 12, no. 7: 1071. https://doi.org/10.3390/ma12071071
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