摘要: |
铝合金等轻质合金由于具有较低的密度与较高的强度,在交通运载器具制造领域得到越来越广泛的应用。搅拌摩擦焊(FSW),作为低热输入的固相连接工艺,是其重要的成形工艺。其中,搅拌头倾角作为保障焊缝成型的重要参量,其对焊接过程的影响还缺乏认识。因此,本研究通过数值模拟的方式,在1.5°、2.5°与4°三组搅拌头倾角条件下,定量分析倾角对焊接过程传热传质的影响规律。在模型中考虑由倾角引起的不完全接触区域及其偏转,并采用非均匀轴向应力、滑移率和摩擦系数。发现当倾角从1.5°增加到4°时,搅拌头后方材料流动能力增强,材料向前进侧迁移的能力提升;界面热流密度增大,剪切层内粘性耗散产热率增大,焊接温度升高。 |
关键词: 搅拌摩擦焊;搅拌头倾角;产热传热;材料流动;数值分析 |
基金项目:国家自然科学基金项目(520**005) |
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The Influence of Tool Tilt Angle on Heat and Mass Transfer in Aluminum Friction Stir Welding Process |
Zhai Ming1, Wu ChuanSong2, Shi Lei2, Song HongTu1
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1. Metals and Chemistry Research Institute, China Academy of Railway Sciences Co. Ltd., Beijing 100081;2. MOE Key Lab for Liquid-Solid Structure Evolution and Materials Processing, Shandong University, Jinan 250061
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Abstract: |
Aluminum alloys are widely applied in manufacturing sector of transportation vehicles because of the low density and high strength. Friction stir welding (FSW), as a solid joining process with low heat input, is the important forming method. The tool tilt angle is an important parameter to ensure weld formation. However, the effects of the tool tilt angle are still unclear. In this research, the influences of tool tilt angle on heat and mass transfer are quantitatively analyzed with three levels of tool tilt angle (1.5°, 2.5° and 4°) in the numerical analysis. The incomplete contact region and the deflection caused by the tool tilt angle are considered in the numerical model. And the non-uniform axial stress, slip rate and friction coefficient are used. It is found that when the tool tilt angle increases from 1.5° to 4°, the flow ability of the material at the trailing side is enhanced, and the material moves farther to the advancing side. The heat flux at the tool/workpiece interface and the viscous dissipation in the shear layer increase, which promotes the welding temperature. |
Key words: friction stir welding;tool tilt angle;heat generation;material flow;numerical analysis |