铝/钢异种金属的超声振动强化搅拌摩擦焊接工艺

采用新型超声振动强化搅拌摩擦焊接工艺实现了6061-T6铝合金以及QP980高强钢的搭接焊, 对比分析了有无超声作用下, 接头的宏观形貌、微观组织和拉伸剪切性能, 同时研究了超声振动对焊接载荷的影响。结果表明: 焊接前对母材施加超声振动, 可以起到软化母材的作用, 促进了材料的塑性流动, 扩大了铝/钢界面区和焊核区, 使更多的钢颗粒随搅拌针旋转进入铝合金侧, 在界面区边缘形成钩状结构, 进而提高了接头的失效载荷; 超声改变了FSW接头断裂位置和断口形貌, 提高了接头力学性能, 在本实验工艺参数范围内, 接头最大的平均失效载荷为4.99 kN; 当焊接速度为90 mm/min, 下压量为0.1 mm时, 施加超声振动使接头的平均失效载荷提高了0.98 kN, 拉剪性能提升28.24%;施加超声振动后轴向力F_z、搅拌头扭矩M_t和主轴输出功率分别下降2.46%, 6.44%和4.59%。

Ultrasonic vibration enhanced friction stir welding process of aluminum/steel dissimilar metals

A novel ultrasonic vibration enhanced friction stir welding(UVeFSW)process was employed to join the 6061-T6 aluminum alloy and QP980 high-strength steel.The macro morphology,microstructure and tensile shear properties of the joint with or without ultrasonic energy were compared and analyzed.Meanwhile,the effects of ultrasonic energy on the welding load were studied.The results show that the ultrasonic vibration applied to the base metal before welding can soften the base metal,promote the plastic flow of the material,expand interface zone and nugget zone of the aluminum/steel,make more steel particles rotate into the aluminum alloy side with the stirring needle,forming a hook structure at the edge of the interface zone which can improve the failure load of the joint.The fracture position and fracture morphology of FSW joint are changed by ultrasonic,and the mechanical properties of FSW joint are improved.Under the welding parameters conducted in the experiment,the maximum average failure load of the joint is 4.99 kN.Under the conditions of a welding rate of 90 mm/min and a depth of 0.1 mm,the application of ultrasonic vibration makes the average failure load of the joint increase by 0.98 kN and the tensile shear performance increase by 28.24%.After applying ultrasonic vibration,the axial force F_z,the tool torque M_t and the spindle power decrease by 2.46%,6.44%and 4.59%respectively.