镀锌钢/铝添加中间夹层Cu、Pb的激光搭接焊研究

Laser Lap Welding of Steel and Aluminum Alloy with Cu, Pb Metal Sandwich Addition

摘要:

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

Abstract:

The laser lap welding experiment with Cu, Pb metal sandwich addition was carried out based on the DC56D+ZF galvanized steel of 1.2 mm thickness and the 6016 aluminum alloy of 1.15 mm thickness. Using optical microscopy, scanning electron microscopy, X-ray diffraction and tensile test, the forming of welding, microstructure, element distribution, fracture morphology and the main phase of the welded joint region and mechanical properties of joints were studied. The results show that when Cu and Pb sandwich is added in steel/aluminum, the average tensile strength and elongation of the steel/aluminum laser welding joints is 49.44 MPa and 1.63% as well as 73.51 MPa and 2.37%, respectively. Compared with that without Cu or Pb sandwich addition, the strength and elongation are improved, and Pb is considered as the best metal sandwich based on improved mechanical properties of joints. Steel and aluminum joint specimen fracture shows a brittle fracture characteristic without metal sandwich, the brittle characteristic is not obvious with Cu metal sandwich, while the ductile characteristic is found with Pb sandwich. When Pb sandwich is added, Fe, Al, Zn, Mg and Pb elements change a lot and the mixing zone width is larger in the transition region of steel/aluminum joints. In addition, a new Mg2Pb intermetallic compound is produced with the better stability, FeAl brittle intermetallic compounds are inhibited, and the mechanical properties of weld metal is improved significantly with Pb sandwich addition