中文摘要：

为了揭示不同轴肩端面对双轴肩搅拌摩擦焊接质量的影响,采用凹/凸四种组合的轴肩对8 mm厚的6061铝合金进行焊接试验,结合焊接转矩、输入功率、前导区温度检测手段,详细分析了不同组合焊缝表面成形、横截面宏观形貌、接头组织形态及力学性能。研究结果表明,在四种轴肩组合中,上凹下凹、上凹下凸的组合能产生纹路细腻、成形美观的焊缝,试样拉伸断口形貌呈典型的韧性断裂;凹/凹组合和凸/凸组合的焊缝关于厚度中心对称,但凹/凸组合的焊缝不再关于厚度中心对称;凹肩表面成形效果强于凸肩,凹肩侧表层焊缝的宽度明显大于凸肩侧对应宽度,且凸肩产生表面沟槽缺陷倾向大于飞边倾向;搅拌区凸肩一侧硬度明显高于凹肩一侧硬度,而在两侧的热影响区,凸肩一侧硬度均低于凹肩一侧硬度。

英文摘要：

In order to reveal the effect of different shoulder on bobbin tool friction stir welding quality,four kinds of combination by concave and convex shoulder are tested for welding aluminum alloy 6061-T6 with thickness 8 mm. Based on the detection of welding torque and leading zone temperature,the weld appearances,visual inspection and hardness of the cross section,microstructure and mechanical properties of BT-FSW joint have been analyzed. The result indicate that two combinations by top concave and bottom convex,top concave and bottom concave can generate the appropriate weld and the corresponding tensile fracture morphology of the joint is typical ductile fracture. The joint is symmetry on the center of thickness when top and bottom shoulder have same shape,but is no longer symmetry when two shoulders have different shape. Compared with the shoulder, concave shoulder has better surface forming effect,the seam close to the concave shoulder has greater width than the seam close to the convex shoulder; convex shoulder prone to produce surface groove defects,but has less tendency to produce flash. The hardness of welding nugget is not uniform,the layer near the convex shoulder side has higher hardness. However, the hardness of the layer near the convex shoulder side was lower than that of the concave shoulder side in the heat affected zone.