铝合金与镀锌钢光纤激光深熔钎焊试验研究

Experimental Investigation of Fiber Laser Keyhole Welding-Brazing of Aluminum to Galvanized Steel

采用光纤激光对车用6016铝合金与镀锌钢无坡口对接接头进行深熔填丝钎焊,对接头焊缝的成形、微观结构和显微组织,以及力学性能进行了分析。扫描电镜(SEM)分析表明,在镀锌钢与钎焊缝界面存在一层薄金属间化合物,不同位置中间层的厚度不尽相同,平均厚度约为4.12μm;能谱(EDS)和X射线衍射(XRD)分析表明生成的金属间化合物主要为τ5-Al8Fe2Si,θ-Al13Fe4和ζ-Al2Fe。拉伸试验中试样断裂于铝合金母材的热影响区,抗拉强度可达162 MPa,断裂接头发生明显的"缩颈"现象;断口分析表明,接头的断裂主要是韧窝断裂。

The butt joint of automotive 6016 aluminum alloy to galvanized steel was achieved by fiber laser keyhole welding-brazing without any grooves. The seam appearance and the microstructures as well as the mechanical properties of the joints were analyzed. The SEM analysis shows that there was a thin layer of the intermetallic compositions （IMCs） on the interface between the galvanized steel and the brazed seam. The thickness of IMCs layer was varied with the joint zone, and the average thickness was 4.12 μm. The EDS and XRD analyses show that the main IMCs were τs-Al8Fe2Si, θ-Al13Fe4 and ξ-A12Fe. The tensile test indicates that the joint was fractured at the heat affected zone （HAZ） of the aluminum plate with obvious appearance of necking in tension. The maximum tensile strenh of the butt ioint was up to 162 MPa. The fracture mode of the joint was ductile fracture.