基于塑性涡流的铝合金搅拌摩擦焊根部弱连接缺陷消除研究

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Abstract：Frictionstir welding（FSW），asanadvancedsolid-state joining technique，has beenwidelyappliedinthe welding of aluminum alloys.However，owing to factors such as the tool structure and the inherent properties of the materials，the jointsare prone toroot kising bond （KB）defects.This kindofdefects notonlyseverelyimpairs the mechanical propertiesof the joints butisalso dificult todetect using non-destructive testing methods.Toadress this issue，this study explores a novel process—vortex flow-based friction stir welding （VFSW）—to eliminate KB defects formed during the FSW of aluminum alloys. Comparative experiments between VFSW and FSW were conducted to investigate the mechanism by which VFSW eliminates KB defects.On this basis，process validation of the VFSW process were carried out on2219 aluminum alloy to identify the appropriate process parameter window. The joint quality was then evaluated through microstructural analysis and mechanical properties testing.The results show that the plastic material vortex formed at the botom of the stir pin during VFSW can drive the material flowing sufficientlyat the root of the weld，effectively eliminating KB defects. Under optimized process parameters，sound welds free of KB defects were achieved. The tensile strength ofthe joints increased with welding speed，reaching up to 330.5MPa ，and fracture did not occur in the regions prone to KB defects.These findings confirm the feasibility of VFSW in eliminating KB defects，providinganeffective approach for achieving high-quality joints in aluminum alloy FSW and laying a theoretical foundation for its engineering application.

Keywords： friction stir welding; aluminum alloy; plastic vortex;root kissing bonc

1序言

在现代工业中，随着对结构轻量化、材料强度与可靠性要求的不断提高，铝合金凭借其高比强度、优异的耐腐蚀性能及良好的成形性，已成为最重要的结构材料之一。（剩余7713字）