中文摘要：

分别采用搅拌摩擦焊（FSW）单道焊和双道焊工艺方法制备铝合金T型接头，对比分析单道、双道FSW-T型接头的缺陷、显微组织、硬度及拉伸性能。结果表明：相对单道焊接头，双道焊工艺可有效降低FSW-T型接头缺陷尺寸及改善缺陷分布状态，隧道缺陷消失或面积降低，吻接缺陷长度降低；双道焊接头在前进侧和后退侧的组织和性能不均匀性明显降低，软化区范围和差异减小；双道焊接头拉伸性能明显提高，在筋板和壁板方向其拉伸性能普遍为母材的80%以上，明显高于单道焊接头的拉伸性能。

英文摘要：

6061-T4 aluminum alloy T-joints were jointed by friction stir welding under single pass and double passes. The welding defects, microstructure, hardness profiles and tensile strength under different welding passes were observed and discussed. The results show that, compared with the single pass welding joints, double passes welding joints have such advantages as follows, the size and distribution of defects are modified, the area of tunnel defects decreases or disappears and the kiss bonding decreases; the inhomogeneity of microstructure and property at advancing side and retreating side decreases greatly; besides, the area and difference of softened zone reduce; the tensile property improves evidently to 80% of that of the base metal, which is better than that of the single pass welding joints.