Effect of Root Flaw on Tensile Behavior of Friction Stir Welded A6061-T6 Aluminum Alloy

摘要

The tensile behavior of friction stir joints containing root flaw in A6061-T6 aluminum alloys was investigated. First, plates of this material were butt-jointed by friction stir welding, and the metallographic observation and micro-hardness analysis were made on the cross-section of the weld. Then, tensile tests were performed in MTS 810 testing machine, and a digital CCD camera was used to monitor the process during testing.. Finally, the tensile fracture surface analysis was examined by scanning electron microscopy (SEM).The results show that the root flaw has no apparent effect on the tensile properties. However, it was observed that a crack about 0.3 mm in length occurred in the root part of the weld center in the early stage of tensile test, and the crack did not further propagate during the sequent tensile experiment. The tensile specimens were all fractured in the heat-affected zone (HAZ) of the retreating side, which is the area coincident with the region of maximum local strain and lowest hardness.