Parametric optimization and microstructural characterization of friction welded aeronautic aluminum alloy 2024
(1. Key Laboratory for Liquid-Solid Structure Evolution and Processing of Materials, Ministry of Education, Shandong University, Ji’nan 250061, China;
2. Institute of Materials Joining, Shandong University, Ji’nan 250061, China;
3. Harbin Welding Institute, Chinese Academy of Machinery Science and Technology, Harbin 150028, China)
2. Institute of Materials Joining, Shandong University, Ji’nan 250061, China;
3. Harbin Welding Institute, Chinese Academy of Machinery Science and Technology, Harbin 150028, China)
Abstract: Continuous drive friction welding was employed to join the aeronautic aluminum alloy 2024. Parametric optimization and microstructural characterization were investigated. Results show that friction pressure is the most significant factor influencing the tensile strength of joints. To obtain a high joint efficiency, the combination of moderate friction pressure, less friction time and higher upset pressure is recommended. The optimized joint efficiency from Taguchi analysis reaches 92% of base metal. Under the optimized experimental condition, the interfacial peak temperature is calculated analytically in the range of 779-794 K, which is validated by experimental data. Fine recrystallized grains caused by the high temperature and plastic deformation are observed in the friction interface zone. The grain refinement is limited in the thermo-mechanically affected zone, where most of matrix grains are deformed severely. The extensive dissolution and limited re-precipitation of strengthening phases result in a lower microhardness in the friction interface zone than that in the thermo-mechanically affected zone.
Key words: AA2024 alloy; continuous drive friction welding; Taguchi analysis; microstructure evolution; mechanical properties