铜/钢异种金属搅拌摩擦焊搭接工艺

采用SKD61模具钢搅拌头对2 mm厚铜/钢异种金属进行搅拌摩擦焊搭接，分析了搭接接头微观组织和力学性能. 结果表明，当搅拌针与钢母材直接接触时，随焊接过程的进行搅拌针不断磨损甚至发生断裂. 焊核区前进侧出现流线区域，在搭接界面结合处形成机械冶金结合. 显微硬度测试显示，铜侧焊核区硬度最高，在搭接界面处硬度分布呈中间高两边低的趋势，接头厚度方向搭接界面处硬度最高. 形成良好结合的搭接接头在拉剪试验中断裂于铜侧热影响区，拉伸断口存在大量韧窝，呈典型韧性断裂模式.

Process study for friction stir lap welding of copper/steel dissimilar metals

T2 copper and Q235 steel dissimilar metals were friction stir lap welded (FSLWed) using the stir tool made by SKD61 die steel. The microstructure and mechanical properties of FSLWed joints were studied. The results showed that the stirring on the Q235 steel of the stir tool leaded to constant wear even fractured. There was stream-lined structure in the advancing side of nugget zone and mechanical and metallurgical bonding was formed in interface zone (IZ). The micro-hardness test showed that the micro-hardness of weld nugget zone (WNZ) was the highest in copper side. The micro-hardness of interface zone (IZ) in weld center was higher than that of the both sides, which meaned that the micro-hardness of IZ was the highest along the thickness direction. The defect-free joint fractured in the heat affect zone (HAZ) of copper side in the tensile-shear test. The fracture surface morphology of lap joints was characterized by dimples, showing that it was ductile fracture.