采用SEM,TEM等对接头界面的微观结构组织进行了表征.结果表明,铜铝套管挤压电阻焊缝组织主要由固溶体和金属间化合物(α,AL2Cu和Al4Cu9)构成.分析认为,铜铝接头接触面上因电阻热和压力引起了温度升高,焊缝区域的高温使界面快速熔化并形成新相,而芯棒施加的压力起到了类似热压焊的作用,挤出共晶组织增加接头焊接接触面积,由于芯棒对焊缝的冷却作用,容易在焊缝中形成柱状晶粒.开发出套管挤压电阻焊接技术,不使用助剂和填充材料,可获得内部洁净度高、接头内无缩径、有效区域内不含共晶组织的铜铝管焊接接头.%The extrusion-resistance welding was developed to join Cu-Al casing pipe. The welded joints have characteristics of high cleanliness and high peel strength, without assistants and filling material. This technology has been widely used in refrigeration industry for the welding of various sized pipes. The micro-structure of the Cu-Al joint was analyzed by SEM and TEM. The results show that Cu-Al joints made by extrusion-resistance welding are mainly composed of solid solution and intermetallic compounds (IMCs)(a, Al2Cu and Al4Cu9). The high temperature generated by the resistance heat and pressure leads to the formation of new phase. The pressure exerted by the mandril extrudes the brittle composition, and enlarges the contact area, which makes the columnar grain easily formed.
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