Microstructure and Mechanical properties of friction stir welded joints in 7A60-T6 super high-strength aluminum alloy

摘要

Friction stir welding of 7A60 aluminum plate of 6 mm thickness were completed in a single pass welding, the weld joints were observed and characterized with metallographic microscope OM, scanning electron microscope SEM, transmission electron microscopy TEM and other tests studied the microstructure of welded joints. The experiment results demonstrate that the tensile strength was affected by welding tool figuration .When the rotating speed is 300 r/min and the wielding speed is 200 mm /min , the good weld is achieved ,and the tensile strength of the joint reaches 488.7 MPa, about 75% of the ultimate strength of the base material with higher welding efficiency. The fracture mode is ductile and brittle mixed fracture. The profile of hardness traverse across the weld exhibits like W and that the heat-affect zone(HAZ) has serious softening. Compared with base metal, the microstructures in the nugget contains fined, equiaxed grains.