Stirring friction welding was employed in the butt welding of the 7075 Al alloy with 8mm thickness in single pass. The desirable joint with tensile strength of 390 MPa can be achieved with the rotating speed of stirring joint at 1180r/min and welding speed at 37.5 mm/min

which is 78% of that of the matrix materials. The microstructure of the joint exhibits typical stirring friction joint structure

consisting of fine equiaxed grain with size of 6

7

μm and finding the absence of enhancing phase in the welding nugget. Micro-hardness of the joint is symmetrically distributed along the welding line

however

the micro-hardness of TMAZ/HAZ transition zone and welding nugget zone is lower than that of the matrix materials

which should be the weak zone of the welds.