【摘要】 目的 为了得到力学性能较好的TA2搅拌摩擦搭接焊接头，研究搅拌头旋转速度对接头宏观成形、微观组织和力学性能的影响规律。方法 采用搅拌摩擦搭接焊方法对1 mm厚的TA2钛金属薄板进行焊接，随后使用Zeiss型图像采集设备和光学显微镜等表征方法，分析接头宏观成形和微观组织变化；采用显微硬度计以及WDS-100型万能拉伸试验机来评估接头的拉剪性能。结果 在保持焊接速度75mm/min不变的情况下，采用旋转速度190 r/min焊接，此时接头成形良好，内部无明显缺陷；当旋转速度增至235 r/min时，焊缝底部开始出现弱连接和微孔缺陷；继续增加旋转速度至300r/min，焊缝底部出现了明显的孔洞缺陷。分析接头显微组织发现，所有接头焊核区均发生了不同程度的动态再结晶，形成了细小的等轴晶，随着旋转速度的增加，焊核区的等轴晶晶粒尺寸反而逐渐变大。接头力学性能测试结果表明，接头的显微硬度呈倒“V”型分布，焊核区的显微硬度明显高于母材硬度，其中当旋转速度为190 r/min时，焊核区上部的最高显微硬度值为269HV，接头的拉剪性能最好，达到4 253.7 N。结论 在焊接速度达到75 mm/min并且旋转速度为190 r/min的情况下，接头展现出最佳的力学性能。更多还原

【Abstract】 The work aims to study the influence of rotation speed on the macro formation, microstructure and mechanical properties of FSLW joints to obtain TA2 friction stir lap welding(FSLW) joints with good mechanical properties. Friction stir lap welding was used to weld TA2 pure titanium sheets with 1 mm thickness. Subsequently, Zeiss-type image acquisition equipment and optical microscopy were used to analyze the formation and microstructure in the joints. A microhardness tester and a WDS-100 universal tensile tester were used to evaluate tensile-shearing properties of the joints. At a constant welding speed of 75 mm/min, when a rotation speed of 190 r/min was applied, the joint was formed well and there were no obvious defects. As the rotation speed increased to 235 r/min, kiss bonding and microporous defects began to appear at the bottom of the weld. Continuously increasing the rotation speed to 300 r/min, obvious hole-defects appeared at the weld bottom. The microstructure analysis revealed that dynamic recrystallization with different degrees occurred into the nugget zone, forming fine equiaxed grains. As the rotation speed increased, the equiaxed grain size gradually increased. The mechanical performances testing results found that the microhardness distribution of FSLW joint presented an inverted "V" shape, and its average microhardness was significantly higher than that of base metal. When the rotation speed was 190 r/min, the highest microhardness value in the upper of the weld nugget zone was 269HV, and the tensile-shearing properties of the joint was the best, the tensile-shearing load reached 4 253.7 N. In conclusion, at a welding speed of 75 mm/min and a rotational speed of 190 r/min, the welded joints show the best mechanical properties.更多还原