异种合金激光-MIG复合熔钎焊界面组织不均匀性与接头力学性能调控机理研究

项目名称： 异种合金激光-MIG复合熔钎焊界面组织不均匀性与接头力学性能调控机理研究

项目编号： No.51475006

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 机械、仪表工业

项目作者： 崔丽

作者单位： 北京工业大学

项目金额： 80万元

中文摘要： 目前国内外对薄板异种合金激光熔钎焊已进行了大量研究，可获得较高力学性能的接头，但是激光熔钎焊存在界面组织不均匀性的问题，随着板厚的增加，界面组织不均匀性问题将更加严重，对接头力学性能影响更为重要。目前对中厚板激光熔钎焊界面组织不均匀性的研究鲜见报道，对界面组织不均匀性的形成机理及其与接头力学性能相关性还缺乏认识。本项目以中厚板铝/钢异种合金对接接头为对象，提出一种聚焦的光纤激光-MIG复合热源熔钎焊新方法，通过接头温度场分布的模拟计算，研究不同工艺参数对界面组织不均匀性及接头力学性能的影响；通过热物理模拟实验、热力学分析计算和生长动力学实验，对界面组织不均匀性进行深入研究，揭示界面金属间化合物不均匀性的形成机理，探讨界面金属间化合物不均匀性对接头拉伸断裂行为的影响，建立界面金属间化合物不均匀性与接头抗拉强度的定量关系，为中厚板异种合金激光-MIG复合熔钎焊的工程应用提供理论基础。

中文关键词： 激光熔钎焊；激光-MIG复合焊；异种材料连接；组织不均匀性；力学性能

英文摘要： Considerable work has been performed on laser welding-brazing of steel to aluminum alloys in thin sheets at home and abroad. The results show that the relatively high tensile strength of the joints has been achieved. However, it has been found that the microstructural inhomogeneity of brittle intermetallic compounds is formed at the welding-brazing interface. With increasing the thickness of the welded joint, the problem of the microstructural inhomogeneity formed at the welding-brazing interface will become more serious. The inhomogeneity of intermetallic compounds formed at the welding-brazing interface has a significant detrimental effect on the mechanical properties of the welded joints. However, very few data have been published on the microstructural inhomogeneity of the intermetallic compounds at the welding-brazing interface for the welded joints in the middle-thickness plates. In addition, the understanding of the formation mechanism of the microstructural inhomogeneity occurred at the welding-brazing interface and the correlation between the microstructural inhomogeneity and the mechanical properties of the joints is inadequate. Therefore, in this study, a novel laser-MIG hybrid welding-brazing process will be proposeded to joining of aluminum to steel plates in the middle thickness, in a butt configuration. The welding temperature field for the laser-MIG hybrid welding-brazing interface by means of the numerical simulation will be calculated to obtain the promising temperature field distribution at the welding-brazing interface. The effects of the different welding parameters on the weld geometry and mechanical properties of the joints will be studied. Based on the the above results, a further investigation on the microstructural evolution of the welding-brazing interface will be carried out by the thermodynamic analysis of the formation of intermetallic compounds and growth kinetics experiment of the intermetallic compounds at the welding-brazing interface. The formation mechanism of the microstructural inhomogeneity of the intermetallic compounds at the laser-MIG hybrid welding-brazing interface will be elucidated. The effects of the microstructural inhomogeneity of the intermetallic compounds at the welding-brazing interface on the tensile fracture properties will be discussed in details. The quantitive relationships between the microstructural inhomogeneity of the intermetallic compounds at the welding-brazing interface and the tensile strength of the welded joints will be established. The results and findings of this study will contribute to an improved understanding of the laser-MIG hybrid welding-brazing process and provide a theoretical basis for laser-MIG hybrid welding-brazing joining of aluminum to steel plates in the middle thickness for future practical engineering applications.

英文关键词： Laser welding-brazing;Laser-MIG hybrid welding;Joining of different materials;Microstructural inhomogeneity;Mechanical properties