基于CuSi3焊丝的激光熔钎焊钢/铝异种金属工艺分析

采用直径1.6 mm的CuSi3焊丝对钢/铝异种金属进行激光填丝熔钎焊.使用光学显微镜观察了焊缝宏观成形，利用SEM，EDS，XRD分析了接头微观组织，通过原位纳米压痕仪和拉伸试验机测试了接头力学性能.结果表明，采用CuSi3焊丝实现了6061铝合金和镀锌板的激光搭接熔钎焊，优化了工艺参数，获得了成形良好的焊缝.焊缝呈现三个特征区:钢侧界面区、焊缝中心区和铜焊丝/铝过渡区.进一步研究表明，铜焊丝/铝过渡区组织包含Cu₉Al₄和CuAl₂金属间化合物，呈现带状、粗大骨架状、细小骨架状夹杂层片状和树枝状四种形貌.铜焊丝/铝过渡区硬度远高于相邻区域，粗大骨架状区域硬度最高达到9.97 GPa，拉伸断裂于粗大骨架状区域，断口呈现脆性断裂.

Microstructure and mechanical properties of laser welding-brazed aluminum alloy to steel with CuSi3 filler metal

Laser welding-brazing of 6061 aluminum alloy to galvanized steel with CuSi3 filler metal was investigated by full-factor experiments. The surface appearances, microstructures and mechanical properties of joints were studied in detail by optical microscope, scanning electron microscope (SEM), EDX analysis and tensile tests. The results indicated that steel-aluminum dissimilar metal lap joint was successfully realized by laser welding-brazing with CuSi3 filler wire, and the joint showed good appearance. The lap joint presented three feature areas:the interface at the side of steel, weld center and the copper solder wire/aluminum transition area at the side of aluminum. Further studies had shown that the copper solder wire/aluminum transition region composed of Cu₉Al₄ and CuAl₂.presented four different morphologies:ribbon, large skeleton-like, small skeleton-like mixed with small amounts of lamellar and dendritic. The hardness of copper solder wire/aluminum transition zone is much higher than that of the adjacent zone, which was up to 9.97 GPa at the coarse skeletal zone. The tensile fracture was in the coarse skeletal zone and the fracture appeared brittle fracture.