Analysis of microstructure and properties in friction-stir welding of 2219 thick plate

Friction stir welding of 2219 aluminum plate with 30 mm thickness were completed in a single pass.When the rotating speed is 1600 r/min and the welding speed is 20 mm/min, the good welds are achieved, and the tensile strength of the weld reaches 278 MPa.For the effect of stirring and temperature in three zones of welds, structure and particles are obviously different. θ(Al₂Cu) micro-particle which strengthen base metal separated out and agglomerated after welding, and it formed lots of large θ particles by reason of thermal recycle of welding, and large agglomerated θ particles whose size is between 10 μm and 50 μm will decrease the tensile strength of welds.