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随焊超声旋压对7075铝合金焊接接头微观组织与力学性能的影响

Effect of ultrasonic spinning with welding on the microstructure and mechanical properties of 7075 aluminum alloy welded joints

  • 摘要: 随焊超声旋压法是一种机械力场和超声能场相结合,随焊控制薄壁件焊接变形的新方法焊接过程中,在熔池后方的特定塑形恢复温度区间施加超声旋压,一方面试件发生高频超声振动,另一方面通过聚能器的高速旋转使高温金属产生塑性变形. 通过超声振动和旋转挤压的复合作用,延展凝固金属的收缩变形,细化晶粒尺寸,达到控制焊接变形,改善焊接接头微观组织,提升力学性能的作用. 设计搭建随焊超声旋压焊接平台,开展7075铝合金的相关焊接试验,获得变形控制效果与焊枪—聚能器间距关系,对焊接接头进行显微组织和力学性能分析. 电子背散色衍射技术(electron back scatter diffraction,EBSD)结果表明,7075铝合金焊缝区晶粒明显得到细化,平均晶粒尺寸由60减小至46.8 μm,柱状晶数目减少,等轴晶数目增加,焊接接头硬度和抗拉强度均得到提升,焊缝区平均硬度由109.7提高到128 HV,抗拉强度由294.71提高到324.64 MPa.

     

    Abstract: The ultrasonic spinning with welding method is a novel approach combining mechanical force field and ultrasonic energy field to control welding deformation of thin-walled components during welding. Its core lies in applying ultrasonic spinning within the specific plastic recovery temperature range behind the molten pool during the welding process, which generates high-frequency ultrasonic vibration in the workpiece while inducing plastic deformation of high-temperature metal through high-speed rotation of the concentrator. Through the combined action of ultrasonic vibration and rotational compression, this method extends the shrinkage deformation of solidified metal, refines grain size, achieving control of welding deformation, improvement of welded joint microstructure, and enhancement of mechanical properties. An ultrasonic spinning with welding platform was designed and constructed, and relevant welding experiments were conducted on 7075 aluminum alloy. The relationship between deformation control effectiveness and torch-concentrator distance was obtained, while microstructural and mechanical property analyses were performed on the welded joints. Electron back scatter diffraction (EBSD) results demonstrate that the weld zone of 7075 aluminum alloy processed by this method exhibits significant grain refinement, with average grain size decreasing from 60 μm to 46.8 μm, accompanied by reduced columnar crystal quantity and increased equiaxed crystal quantity. The welded joints obtained through this method show improved hardness and tensile strength, with average weld zone hardness increasing from 109.7 HV to 128 HV, and tensile strength rising from 294.71 MPa to 324.64 MPa.

     

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