Effects of Brass Interlayer on Mechanical Properties of Friction Stir Welded AA 6061-T6 Joint

The most important issues in the joining of similar aluminum alloy are softening of weld zone and reduction in tensile strength of joints. Use of a metallic interlayer can resolve these issues. In the present research work, effect of brass interlayer on the properties of friction stir welded 6061-T6 aluminum alloy was studied. X-ray diffraction analysis was carried out to investigate the phase composition with brass interlayer. Al2Cu and Al4Cu9 intermetallic compounds were formed at the welded zone. Mechanical properties were examined through the tensile and microhardness testing. Tensile test results reveal that the use of brass interlayer is a good solution to improve the joint strength, as the insertion of brass interlayer enhances the joint strength up to 36%. In addition, use of brass interlayer enhances the microhardness at the weld zone and the softening issue has been resolved to some extent. Field emission scanning electron microscopy was used to investigate the mechanism of fracture behavior in fractured tensile specimens. However, insertion of brass interlayer slightly changes the ductile fracture toward brittle fracture.