超声冲击处理对2A12铝合金焊接接头表层组织性能的影响

Effect of Ultrasonic Impact Treatment on Microstructure and Properties of Surface Layer of 2A12 Aluminum Alloy Weld Joint

用手工氩弧焊(TIG)、ER5356焊丝对2A12铝合金板进行了焊接,用超声冲击处理技术对焊接接头进行了全覆盖强化处理;借助金相显微镜、X射线衍射仪、透射电镜和显微硬度计对超声冲击强化处理前后接头表层的组织和性能进行了分析。结果表明,超声冲击处理可在接头表层形成尺寸均匀、取向随机分布的细晶组织,大幅消除了气孔、缩松等焊接缺陷,接头显微硬度显著提高。讨论了超声冲击导致的晶粒细化和位错增殖对接头强度的影响。

Aluminum alloy 2A12 was welded using ER5356 welding wire of TIG. Then the welded joint was strengthened by ultrasonic impact treatment （UIT）. The weld toe, weld zone, heat affect zone （HAZ） and parent zone were treated by ultrasonic impact treatment （UIT）. The microstructure and properties of the plastic deformation layer were characterized by optical microscopy, X-ray diffraction （XRD）, transmission electron microscopy （TEM） and micro-hardness test. Results indicate that the dentric coarse grains near the surface of weld joint were refined into ultra fine grains with random crystallographic orientations. Defects such as gas cavity and shrinkage porosity in the weld zone were reduced substantially after UIT. The metallurgical structure of the near surface material of the weld zone was densified. The hardness of the surface of the welded joint was also improved distinctly. The strengthening mechanism of grain refinement and dislocation multiplication by UIT was discussed.