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对1.2 mm厚DC56D+ZF镀锌钢和1.15 mm厚6016铝合金平板试件进行了添加中间夹层Cu、Pb的激光搭接焊实验研究,利用体视显微镜、卧式金相显微镜、扫描电镜、X射线衍射仪、微机控制的电子万能试验机等手段研究了钢/铝焊缝的表面成形性、接头各区域的金相组织、界面元素分布、断口形貌、主要物相与接头力学性能。结果表明:添加中间夹层Cu、Pb,焊接接头的平均抗拉强度分别为49.44、73.51 MPa,伸长率分别为1.63%、2.37%,与未添加夹层相比,抗拉强度和伸长率提高,其中Pb提高效果优于Cu;不加夹层,钢/铝试样断口呈明显脆性断裂特征;加入夹层Cu,脆性断裂特征不明显;而加入夹层Pb,试样断口呈韧性断裂特征;添加夹层Pb,钢/铝界面连接处Fe、Al、Zn、Mg、Pb元素变化剧烈,混合区宽度大,新生成Mg2Pb金属间化合物的结构比FeAl金属间化合物稳定,能抑制脆性FeAl金属间化合物生成。这是添加夹层Pb明显改善钢/铝焊接接头力学性能的重要原因。
The laser lap welding experiment of adding intermediate Cu and Pb was carried out on 1.2 mm thick DC56D + ZF galvanized steel and 1.15 mm thick 6016 aluminum alloy flat plate specimen. The stereoscopic microscope, horizontal optical microscope, scanning electron microscope, X-ray diffraction and computer-controlled electronic universal testing machine were used to study the surface formability of steel / aluminum weld, the metallographic structure, the interface element distribution, the fracture morphology, the main phase and the mechanical properties of joints. The results show that the tensile strength and elongation of Cu, Pb and welded joints are 49.44 and 73.51 MPa respectively, the elongation rates are 1.63% and 2.37% respectively, Among them, the effect of Pb is better than that of Cu; the fracture of steel / aluminum specimen is obviously brittle fracture without intercalation; while the addition of intercalation Cu, brittle fracture characteristics are not obvious; when intercalated Pb is added, the fracture of specimen shows ductile fracture; The Fe, Al, Zn, Mg and Pb elements change sharply at the interface of steel / aluminum, and the width of the mixed zone is large. The structure of the newly formed Mg2Pb intermetallic compound is more stable than that of the FeAl intermetallic compound and can inhibit the formation of the brittle FeAl intermetallic compound. This is an important reason that the addition of interlayer Pb significantly improves the mechanical properties of steel / aluminum welded joints.