铝合金摆动激光-电弧复合焊接特性及匙孔、熔池动态行为

Porosity defects and softening behavior of the joints are the main problems in laser-arc welding of thick-section aluminum alloys. The thermal and flow fields are optimized by applying the weaving laser. Porosity defects in the weld are suppressed, since the keyhole stability is improved and less bubbles are generated. Besides, bubbles could escape from the molten pool easily due to the stirring effect. The mechanical properties of the joints are improved, because the weld microstructures are improved and weld defects are suppressed. In the present study, the arc and droplet transfer behaviors are investigated during the weaving laser-arc hybrid welding process. The influences of weaving laser and arc interaction on droplet transfer behavior are illuminated. The main weaving laser parameters and the optimized parameter range are obtained. The relationship of weaving parameters, weld formation and porosity defects are analyzed. Based on the process monitoring and numerical simulation results, the heat and mass transfer mechanisms of molten pool are clarified. The effects of keyhole and molten pool dynamic behaviors on the porosity defects are discussed. The influences of thermal cycle and molten pool flow behavior on the microstructures and solidification characteristics of the weld are studied. The effects of weld microstructures and defects on the mechanical properties of joints are analyzed. The research achievements will lay the theoretical and technical foundation for the application and development of weaving laser-arc hybrid welding.

针对厚板铝合金激光-电弧复合焊焊缝气孔缺陷多及接头软化问题，通过激光束的摆动优化熔池热场和流场，增强匙孔的稳定性减少气泡的产生，对熔池的搅拌作用有助于气泡逃逸，有效抑制焊缝气孔缺陷；改善焊缝组织及缺陷状态提高接头的力学性能。本项目研究摆动激光作用下铝合金激光-电弧复合焊电弧及熔滴过渡行为，阐明摆动激光与电弧的交互作用机制及其对熔滴过渡行为的影响；系统分析不同激光摆动参数下焊缝成形机制及气孔分布特征，建立激光摆动参数-焊缝成形-气孔特征之间的相关性；进一步，研究摆动激光-电弧复合焊匙孔、熔池的动态行为并阐明其对焊缝气孔的影响及抑制机制；明确摆动激光-电弧复合焊温度场分布及熔池流场特性对焊缝金属凝固行为的影响，建立焊缝组织特征、缺陷状态与接头力学性能之间的相关性。通过本项目的研究，为铝合金摆动激光-电弧复合焊接新方法的应用与发展奠定理论和技术基础。

针对厚板铝合金激光-电弧复合焊焊缝气孔缺陷多及接头软化的问题，通过激光束的摆动，改善匙孔的稳定性，对熔池的搅拌作用有助于气泡逃逸，有效抑制焊缝气孔缺陷，改善焊缝组织及缺陷状态提高接头的力学性能。本项目系统研究了摆动激光作用下铝合金激光-电弧复合焊电弧及熔滴过渡行为，阐明了摆动激光与电弧的交互作用机制对熔滴过渡行为的影响；系统分析了不同激光摆动参数下焊缝成形及气孔分布特征，建立摆动参数-焊缝成形-气孔特征之间的相关性；进一步，研究了摆动激光-电弧复合焊匙孔、熔池的动态行为并阐明其对焊缝气孔的影响及抑制机制；明确摆动激光-电弧复合焊温度场分布及熔池流场对焊缝金属凝固行为的影响，建立了焊缝组织特征、缺陷状态与接头力学性能之间的相关性。本项目的研究成果，为铝合金摆动激光-电弧复合焊接新方法的应用与发展奠定技术基础。