Microstructure and mechanical properties of Al-Zn-Mg-Cu (7075) alloy tubes prepared via power stagger spinning
(1. College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan 030024, China;
2. Shanxi Key Laboratory of Intelligent Underwater Equipment, Taiyuan 030024, China;
3. College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China)
2. Shanxi Key Laboratory of Intelligent Underwater Equipment, Taiyuan 030024, China;
3. College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China)
Abstract: The tubes of 7075 aluminum alloy were fabricated by power stagger spinning at 400 °C (HS) and room temperature (RTS), and then the microstructure evolution and mechanical properties were investigated. Results show that the grains after spinning are refined prominently, and the tubes after 60% and 70% thickness reduction (HS-60% and HS-70%) are dominated by the deformed structure, while the recrystallized structure is dominant in the tube after 85% thickness reduction at 400 °C (HS-85%). Furthermore, a bimodal grain structure with a weak Cube texture is obtained in the HS-85% sample due to the emergence of the dynamic recrystallization (DRX) and abnormal grain growth. As the thickness reduction increases from 0% to 85% during spinning at 400 °C, the yield strength (YS) and ultimate tensile strength (UTS) increase first and then decrease, while the elongation decreases first and then increases. Compared with that of the HS-85% sample, the UTS and YS of RTS-85% sample are 613.5 and 567.9 MPa, respectively, which are improved by 33.7% and 57.4%, while the elongation is only 7.3%.
Key words: 7075 aluminum alloy; power stagger spinning; microstructure evolution; bimodal grain structure; abnormal grain growth; mechanical properties