搭接方式对铝/钢异种金属激光焊接接头组织性能的影响

Effect of Lap Mode on Microstructure and Properties of Al/Steel Dissimilar Metal Laser Welded Joints

采用激光深熔焊对2 mm厚的AA6061-T4铝合金和1.5 mm厚的Q235镀锌钢异种金属进行焊接,主要针对铝上钢下和铝下钢上两种搭接方式进行比较研究。从接头截面形貌、组织表征、相分析、拉伸剪切性能等方面对两种搭接方式得到的铝/钢接头进行了比较。结果表明:铝上钢下接头的深宽比小于1,铝下钢上接头的深宽比大于1。接头中有氢气孔、锌蒸气孔及工艺型气孔等缺陷的生成。铝上钢下接头的整个焊缝金属由铁铝金属间化合物组成,该接头的平均抗剪强度为74.2 N/mm。铝下钢上接头仅在焊缝金属和铝基体之间形成一层金属间化合物,该接头的平均抗剪强度为163.4 N/mm。

The welding of dissimilar metals of 2 mm thick AA6061-T4 and 1.5 mm thick galvanized Q235 carbon structural steel was carried out by using laser keyhole welding process, and the two overlap modes of Al-on-steel and steel-on-Al were investigated comparatively. The Al/steel joints obtained by the two overlap modes were compared from the following views: morphology of the cross-section of the joints, microstructure characterization and phase analysis, tensile shear properties, etc. The results show that the depth-to-width ratio is lower than 1 for the joints with Al-on-steel, while the depth-to-width ratio is higher than 1 for the joints with steel-on-Al. Defects like hydrogen pore, Zn pore and porosity could be observed. The entire weld metal of the joints with Al-on-steel is composed of Fe-Al intermetallic compounds(IMCs), and the average shear strength of the joints is 74.2 N/mm. Only a Fe-Al IMCs layer between the weld metal and Al substrate in the joints with steel-on-Al is formed, and the average shear strength of the joints is 163.4 N/mm.