汽车轻量化及对车身安全性的需求，使得先进高强钢与铝合金异质材料的连接构件在汽车制造领域具有广阔的应用前景。然而物理冶金及化学性能的巨大差异使其连接的可靠性成为影响构件安全运行的关键。双光束激光熔钎焊由于其独特的优点成为异质材料连接中最有前途的方法之一，然而由于该方法在国内尚属起步阶段，为深入理解异质材料构件双光束激光熔钎焊过程特征及接头服役的关键基础问题，研究熔钎焊接头的界面行为及其破坏机理十分必要。因此，本课题拟采用双光束激光熔钎焊方法对DP980与AA7003异质材料构件进行连接，系统研究异质金属熔钎焊接头成形特征，建立双光束激光过程参数与熔钎焊接头成形质量的内在联系；基于接头物相结构的系统表征，掌握界面处物相的形成和演化特征，揭示界面层微观组织与过程参数的内在关联机制；同时开展接头疲劳破坏试验研究，阐明微观组织结构对熔钎焊接头疲劳裂纹萌生及扩展的影响机制，为构件失效分析提供理论基础。

The increasing requirement of reduction weight and safety for vehicle induces a promising application for the components advanced-high strength steel/Al alloy dissimilar materials in automobile manufacturing. However, it is a big issue affecting the high quality of joint due to the great difference in physical metallurgy and chemical properties. As a new joining method for dissimilar materials, dual beam laser welding-brazing technology is a best choice for its unique advantage. It is necessary to be elucidated on phase formation and damage mechanism happened in welding-brazing process and service. In this proposal, dual beam laser welding-brazing technology will be employed to join DP980/AA7003, the joint formation process will be systematic investigated and then to build the correction between process parameters and joint quality. Based on the characterization of phases structure to pursue the formation and evaluation of phases in the interface, therefor to reveal the relationship between heat input and microstructure. And also the fatigue test of welding-brazing joint will be carried out to clarify the influence of phase morphology and size on fatigue behavior, and reveal the damage mechanism of joint.