Friction stir welding of small-dimension Al3003 and pure Cu pipes

Small-dimension Al3003 pipe and pure copper pipe of thin wall (Al: 1.5 mm; Cu: 1 mm) and small diameter (19 mm) were successfully joined by a developed welding method with a specially-designed friction stir welding (FSW) system. A distinctive temperature history due to heat accumulation was identified as an important feature for FSW of small-dimension pipes, leading to distinctive variations of surface condition, macro-/micro-structure along the circumferential weld seam. Hardness distribution, tensile strength, ductility and fracture modes were found to change correspondingly along the weld seam.