Enhanced fatigue properties of AA5086 friction stir weld joints by Cu-reinforcement

AA5086-H116 plates were welded, with and without copper (Cu)-reinforcement, using friction stir welding. Cu-reinforcement during the solid state welding process developed a localized composite (AA5086/Cu) which was processed using single-pass and double-pass, both. A significant improvement of similar to 15%, similar to 13% in the microhardness, and similar to 95%, similar to 98% in the weld joint efficiency was achieved during the single-pass and double-pass of the Cu-reinforced joints, respectively. The uniaxial load-controlled cyclic tests under fully-reversed conditions were performed in ambient environment to study the fatigue response of the welded joints. The fatigue strength of single-pass (= 65 MPa) and double-pass (= 65 MPa) Cu-reinforced weld joints was improved by similar to 18%, as compared to the simple weld joints (= 55 MPa) without any reinforcement. The location of failures in the samples tested under fatigue loading was shifted from thermo-mechanical affected zone in simple weld to base material in the double-pass Cu-reinforced welded joints. A deeper analysis of broken specimens revealed the role of surface irregularities, residual stresses and microstructural inhomogeneity in the improved fatigue properties and the associated damage mechanisms, which are shown and discussed in this study.

Automated summary

AA5086-H116 plates were welded with and without copper (Cu)-reinforcement using friction stir welding. Single-pass and double-pass processes were applied to develop a localized composite (AA5086/Cu). The addition of Cu-reinforcement improved the microhardness, weld joint efficiency, and fatigue strength of the welded joints.