铜/铝异质金属层状复合板搅拌摩擦焊接技术研究

Research on Friction Stir Welding Technology of Al-Cu Composite Plates

选用复层占比约23%的6.5 mm厚铜(复层)/铝(基层)金属层状复合板作为焊接对象,研究对其进行搅拌摩擦焊接(FSW)的可行性;同时重点研究焊接工具的作用位置(复层在上和基层在上)对于焊接过程的影响;此外,结合有限元模拟技术,分析FSW过程中焊接工具的热力耦合作用对于铜复层流动行为的影响,以及接头中微观组织,尤其是界面区组织的变化。结果表明,在下压量为0.2 mm、焊接速度为150 mm/min和旋转速度为900 r/min的焊接参数下,当采用铝基层在上的焊接方式时,铜复层侧受焊接工具热机作用影响较弱,向上迁移作用较小,并且由于底部作用温度较低、铜复层熔点较高以及导热性较强,因此容易导致在接头底部形成明显的隧道缺陷;当铜复层在上时,可以获得成形良好的FSW接头,由于焊接过程中后退侧和前进侧温度存在差异,在温度较低的后退侧中的铝-铜界面区域,仅形成了少量的Al-Cu金属间化合物层;在温度较高的前进侧中铝-铜界面区域,则由较厚的脆性Al-Cu金属间化合物层组成,该FSW接头的平均抗拉强度为85.2 MPa,约为母材抗拉强度的62.7%。

In this research,6.5 mm thick Al/Cu composite plates with Cu cladding plate fraction of 23%were selected for friction stir welding(FSW).The influence of welding position(Cu cladding plate up and Al base plate up)on the welding process was investigated emphatically.In addition,the influence of thermo-mechanical coupling on the flow behavior of Cu cladding plate,the microstructure evolution mechanisms in the welded joint,especially the interfacial microstructure were analyzed combined with numerical simulation technology.The results show that when Al base plate is placed upon the Cu cladding plate,the tunnel defect is created under the process parameters of 0.2 mm plunge depth,900 r/min rotation speed and 150 mm/min welding speed in the weld joint,because of the weakly influence of the action of thermal mechanical coupling on the Cu cladding plate,the weakly interaction of upward migration,the lower temperature effect on high-melting point high-conductivity copper cladding plate.When Cu cladding plate is placed upon the Al base plate,the joint with perfect appearance could be prepared under the same welding parameters.Due to the temperature variations of the advancing side and the retreating side during the FSW process,a small number of Al-Cu intermetallic compound interlayer are formed in the Cu/Al interface of the lower temperature retreating side and hook zone,and the thick Al-Cu intermetallic compound interlayer is formed in the Cu/Al interface of the higher temperature advancing side.The average tensile strength of the joint is 85.2 MPa,which is about 62.7%of the tensile strength of the base metal.