Achievement of nearly-equal-strength repaired exceeded tolerance hole of 2024 aluminum alloy by ultrasonic-assisted radial-additive friction stir repairing
Shude Ji, Jirui WANG, Zhiqing Zhang, Hua Liu, Yifei Sun, Yumei Yue
Abstract
Radial-Additive Friction Stir Repairing (R-AFSR), which has been developed in recent years for the exceeded tolerance hole, is an innovative technology to realize the one-step repairing. Enhancing the repair strength of exceeded tolerance hole is necessary and meaningful from the perspective of suiting more and more wide-scrapped equipment in the industrial field. Ultrasonic-Assisted R-AFSR (UA-RAFSR) is proposed as a strategy to achieve the 2024 aluminum (Al) alloy repaired hole with high strength. Analyses of microstructure formation indicate that the addition of ultrasonic eliminated the kissing bond and “S” line, refined the grain size, enlarged the interfacial bonding area and enhanced the atomic diffusion. Thus, the mechanical properties of 2024 Al alloy repaired hole were heightened by ultrasonic, and the maximum compressive shear and tensile strengths respectively reached 214.5 MPa and 297.3 MPa, which were 98.6% and 94.0% of those of the standard mechanical hole. The research results confirm that the UA-RAFSR is a powerful technology for the nearly-equal-strength repair of exceeded tolerance hole.