钛/铝冷弧MIG+激光双面复合熔钎焊界面结构演变与性能调控研究

Key difficulties and bottlenecks in welding-brazing titanium to aluminum are the interfacial microstructure inhomogeneity and the excessive formation of brittle intermetallics. A novel cold arc MIG + laser double side hybrid welding technology is proposed to welding-brazing Ti/Al dissimilar joint in the subject. In order to improve the distribution of welding heat input along the Ti/Al interface, low-power pulsed laser is adopted to the back of the seam. Mechanical properties improvement of the welded-brazed joint could be realized thanks to suppression of the Ti-Al intermetallics formation and homogenization of the interfacial microstructure. The key point of the research is to investigate the evolution rules of Ti/Al interfacial microstructure with the variation of welding process. Relational model of welding-brazing process, welding heat input distribution and Ti/Al interfacial microstructure would be established based on experimental analysis and numerical simulation. Internal relations among welding-brazing process, Ti/Al interfacial microstructure and mechanical properties of the joint should be acquired by further study on correlations among the interfacial microstructure, weld shaping and the joint properties, and eventually regulation mechanism of weld shaping compatibility with Ti/Al interfacial microstructure should be revealed. The conduct and completion of the research would be of experimental and theoretical significance for reliable joining of Ti/Al dissimilar alloys using fusion welding technologies.

Ti/Al界面结构的不均匀性和过量脆性金属间化合物的生成是钛/铝熔钎焊面临的瓶颈和关键问题。本项目拟采用冷弧MIG+激光双面复合焊接技术对钛与铝进行熔钎焊研究。通过焊缝正面冷弧MIG输入、背面低功率脉冲激光输入来调节和改善Ti/Al界面的热输入分布，在抑制Ti-Al金属间化合物生成的同时基本实现界面结构的均匀化，达到强化接头性能的目的。本项目重点研究不同连接工艺下Ti/Al界面结构的演变规律，通过试验分析和模拟计算构建熔钎焊工艺—界面热输入分布—界面结构之间的理论关系模型。通过深入研究接头焊缝成形、Ti/Al界面结构与接头力学性能的相关性，揭示复合焊工艺下接头焊缝成形与Ti/Al界面结构的兼容调控机理。本项目的实施和完成，可为采用熔焊工艺实现钛与铝的可靠连接提供重要的理论基础和技术依据。

钛/铝复合结构在航空航天和汽车工业的轻量化结构中具有良好的应用前景，必须要解决钛/铝熔钎焊面临的组织结构不均和脆性金属间化合物过量形成问题。项目针对钛与铝冷弧MIG+激光双面复合熔钎焊中Ti/Al界面结构演变和接头性能调控机理展开研究，顺利完成了计划任务书要求的研究内容。获得的主要成果有：（1）构建了复合焊工艺—Ti/Al界面热输入分布—Ti/Al界面结构的理论关系；（2）获得了接头焊缝成形、Ti/Al 界面特性对接头力学性能的影响规律。基于项目研究内容，共发表科技论文9篇，其中SCI、EI收录论文7篇；申请国家发明专利6项；出版学术专著《钛/铝特种氩弧焊工艺》1部。项目组成员参与国内会议8人次，会议特邀报告2人次。依托项目，共培养已毕业博士研究生1名，硕士研究生2名；培养在读研究生3名。.项目揭示了复合焊工艺下Ti/Al 界面结构的演变行为，揭示了接头焊缝成形与Ti/Al 界面特性的兼容调控机理。通过优化工艺，获得了焊缝成形、界面特性及力学性能俱佳的Ti/Al熔钎焊接头。为采用熔焊工艺实现钛与铝的可靠连接提供了重要的理论基础和技术依据。