Fluid Flow Characteristics and Weld Formation Quality in Gas Tungsten Arc Welding of a Thick-Sheet Aluminum Alloy Structure by Varying Welding Position
This study aims to reveal the cause of different weld formation quality for varying welding position in the GTAW (Gas Tungsten Arc Welding) of a thick-sheet aluminum alloy structure. The fluid flow characteristics of weld pools are investigated by CFD (Computational Fluid Dynamic) modeling and high-...
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MDPI AG
2018-07-01
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| Series: | Applied Sciences |
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| Online Access: | http://www.mdpi.com/2076-3417/8/8/1215 |
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| author | Baohua Chang Hong Xiao Jinle Zeng Shuo Yang Dong Du Jianling Song Guoliang Han |
| author_facet | Baohua Chang Hong Xiao Jinle Zeng Shuo Yang Dong Du Jianling Song Guoliang Han |
| author_sort | Baohua Chang |
| collection | DOAJ |
| description | This study aims to reveal the cause of different weld formation quality for varying welding position in the GTAW (Gas Tungsten Arc Welding) of a thick-sheet aluminum alloy structure. The fluid flow characteristics of weld pools are investigated by CFD (Computational Fluid Dynamic) modeling and high-speed imaging for the climbing and flat welding positions, which correspond to the start and finish ends of the welds of the structure, respectively. Results show that the directions of gravity relative to weld pools may notably affect the fluid flows in weld pools for different welding positions. For flat welding, gravity will accelerate the fluid flow in the direction of sheet thickness only and in turn result in a high velocity downwards, which implies a good penetrating capability. Welds of good formation with smooth surface and consistent width can be produced under flat welding position. In contrast, for climbing welding, gravity will act on the molten metal in both the direction of sheet thickness and the lateral direction of the weld pool. As a result, the velocity in sheet-thickness direction is decreased, which implies a decreased penetrating capability. Meanwhile, the velocity backwards is increased in the top portion of the weld pool, which makes the molten metal apt to flow out of the weld pool. Both the decreased penetrating capability and the accelerated molten metal outflow would render the climbing welding process unstable, and result in welds of poor formation with uneven weld surface and inconsistent weld width. Based on the study, possible methods are proposed that could be used to improve the weld formation quality when welding thick-sheet aluminum alloys structures using various welding positions. |
| first_indexed | 2024-12-23T19:20:53Z |
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| institution | Directory Open Access Journal |
| issn | 2076-3417 |
| language | English |
| last_indexed | 2024-12-23T19:20:53Z |
| publishDate | 2018-07-01 |
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| series | Applied Sciences |
| spelling | doaj.art-97189745b0654ed7b45e852c65608da32022-12-21T17:34:10ZengMDPI AGApplied Sciences2076-34172018-07-0188121510.3390/app8081215app8081215Fluid Flow Characteristics and Weld Formation Quality in Gas Tungsten Arc Welding of a Thick-Sheet Aluminum Alloy Structure by Varying Welding PositionBaohua Chang0Hong Xiao1Jinle Zeng2Shuo Yang3Dong Du4Jianling Song5Guoliang Han6State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, ChinaTianjin Long March Launch Vehicle Manufacturing Co., Ltd., Tianjin 300462, ChinaState Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, ChinaState Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, ChinaState Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, ChinaTianjin Long March Launch Vehicle Manufacturing Co., Ltd., Tianjin 300462, ChinaTianjin Long March Launch Vehicle Manufacturing Co., Ltd., Tianjin 300462, ChinaThis study aims to reveal the cause of different weld formation quality for varying welding position in the GTAW (Gas Tungsten Arc Welding) of a thick-sheet aluminum alloy structure. The fluid flow characteristics of weld pools are investigated by CFD (Computational Fluid Dynamic) modeling and high-speed imaging for the climbing and flat welding positions, which correspond to the start and finish ends of the welds of the structure, respectively. Results show that the directions of gravity relative to weld pools may notably affect the fluid flows in weld pools for different welding positions. For flat welding, gravity will accelerate the fluid flow in the direction of sheet thickness only and in turn result in a high velocity downwards, which implies a good penetrating capability. Welds of good formation with smooth surface and consistent width can be produced under flat welding position. In contrast, for climbing welding, gravity will act on the molten metal in both the direction of sheet thickness and the lateral direction of the weld pool. As a result, the velocity in sheet-thickness direction is decreased, which implies a decreased penetrating capability. Meanwhile, the velocity backwards is increased in the top portion of the weld pool, which makes the molten metal apt to flow out of the weld pool. Both the decreased penetrating capability and the accelerated molten metal outflow would render the climbing welding process unstable, and result in welds of poor formation with uneven weld surface and inconsistent weld width. Based on the study, possible methods are proposed that could be used to improve the weld formation quality when welding thick-sheet aluminum alloys structures using various welding positions.http://www.mdpi.com/2076-3417/8/8/1215aluminum alloyswelding positionsfluid flow behaviorsComputational Fluid Dynamics (CFD)weld formation |
| spellingShingle | Baohua Chang Hong Xiao Jinle Zeng Shuo Yang Dong Du Jianling Song Guoliang Han Fluid Flow Characteristics and Weld Formation Quality in Gas Tungsten Arc Welding of a Thick-Sheet Aluminum Alloy Structure by Varying Welding Position Applied Sciences aluminum alloys welding positions fluid flow behaviors Computational Fluid Dynamics (CFD) weld formation |
| title | Fluid Flow Characteristics and Weld Formation Quality in Gas Tungsten Arc Welding of a Thick-Sheet Aluminum Alloy Structure by Varying Welding Position |
| title_full | Fluid Flow Characteristics and Weld Formation Quality in Gas Tungsten Arc Welding of a Thick-Sheet Aluminum Alloy Structure by Varying Welding Position |
| title_fullStr | Fluid Flow Characteristics and Weld Formation Quality in Gas Tungsten Arc Welding of a Thick-Sheet Aluminum Alloy Structure by Varying Welding Position |
| title_full_unstemmed | Fluid Flow Characteristics and Weld Formation Quality in Gas Tungsten Arc Welding of a Thick-Sheet Aluminum Alloy Structure by Varying Welding Position |
| title_short | Fluid Flow Characteristics and Weld Formation Quality in Gas Tungsten Arc Welding of a Thick-Sheet Aluminum Alloy Structure by Varying Welding Position |
| title_sort | fluid flow characteristics and weld formation quality in gas tungsten arc welding of a thick sheet aluminum alloy structure by varying welding position |
| topic | aluminum alloys welding positions fluid flow behaviors Computational Fluid Dynamics (CFD) weld formation |
| url | http://www.mdpi.com/2076-3417/8/8/1215 |
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