【摘要】 目的 针对超薄板铝/钢微搅拌摩擦搭接焊中形变翘曲及界面结合难以有效控制的问题，通过调节旋转速度来研究其对接头成形、界面组织及力学性能的影响规律。方法 以5052铝合金与304不锈钢为研究对象，在不同旋转速度条件下进行微搅拌摩擦搭接焊实验，结合焊缝表面成形、界面微观组织结构表征及拉剪性能测试，分析材料塑性流动行为随工艺参数变化所呈现的接头成形及力学性能的变化规律。结果 当采用无针式搅拌头、旋转速度为375 r/min时，热输入不足，搅拌区塑性流动受限，焊核区存在轻微回填不充分现象；在旋转速度为475 r/min下，材料流动与热输入达到平衡，成形质量最佳；当旋转速度为600～750 r/min时，热输入过大，板材翘曲变形严重，材料挤出及堆积加剧，导致焊核区回填不足，与接头区域减薄增大。当旋转速度超过最优参数区间后，减薄量显著增加，有效承载面积减小，成为力学性能下降的主导因素。在旋转速度475 r/min条件下，焊缝表面成形较为平整，拉剪力可达860 N，继续提高转速将导致断裂区域由界面转移至铝侧热机影响区。结论 合理控制旋转速度是实现超薄板铝/钢微搅拌摩擦焊中接头成形与界面冶金结合协同调控的关键，旋转速度过高会引起形变翘曲缺陷的产生，进而导致材料塑性流动失稳与接头减薄加剧，劣化了接头的力学性能。更多还原

【Abstract】 To address the difficulty in effectively controlling deformation warping and interface bonding in the micro friction stir lap welding(μFSLW) of ultra-thin aluminum/steel plates, the work aims to systematically investigate the effect of adjusting the rotation speed on the formation, interfacial microstructure, and mechanical properties of joints. With 5052 aluminum alloy and 304 stainless steel as research objects, experiments on micro friction stir lap welding were conducted at different rotation speeds. By analyzing weld surface formation, characterizing interfacial microstructure, and conducting lap-shear performance tests, the variations in joint formation and mechanical properties due to changes in material plastic flow behavior with process parameters were examined. When a pinless stirring tool was used at a rotation speed of 375 r/min, the heat input was insufficient, limiting plastic flow in the stirring zone and resulting in slight insufficient backfilling in the weld nugget zone. At a rotation speed of 475 r/min, the material flow and heat input reached a balance, achieving optimal forming quality. When the rotation speed ranged from 600 to 750 r/min, excessive heat input caused severe plate warping deformation, intensified material extrusion and accumulation, leading to insufficient backfilling in the weld nugget zone and increased thinning in the joint region. When the rotation speed exceeded the optimal parameter range, the thinning amount increased significantly and the effective load-bearing area decreased, which became the dominant factor in the decline of mechanical properties. At a rotation speed of 475 r/min, the weld surface exhibited relatively smooth formation, and the lap shear strength reached 860 N. Further increasing the rotation speed would cause the fracture location to shift from the interface to the thermo-mechanically affected zone on the aluminum side. Effectively controlling the rotation speed is the key to achieving coordinated regulation of joint formation and interfacial metallurgical bonding in ultra-thin Al/steel by micro friction stir welding. Excessively high rotation speed can induce deformation and warping defects, which in turn leads to instability in material plastic flow and increased joint thinning, thereby degrading the mechanical properties of the joint.更多还原