New method and mechanism for quickly obtaining quenching sensitivity temperature range of 7055 aluminum alloy
(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. School of Materials Science and Engineering, Hubei University of Automotive Technology, Shiyan 442002, China;
3. Light Alloy Research Institute, Central South University, Changsha 410083, China;
4. State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, China;
5. School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China)
2. School of Materials Science and Engineering, Hubei University of Automotive Technology, Shiyan 442002, China;
3. Light Alloy Research Institute, Central South University, Changsha 410083, China;
4. State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, China;
5. School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China)
Abstract: An alternating temperature heat treatment (ATHT) method with time-saving and resource-saving advantages was employed to measure the quenching sensitivity temperature range of the spray-deposited 7055 aluminum alloy based on hardness and electrical conductivity. Additionally, the microstructure evolution during ATHT was characterized by transmission electron microscopy (TEM). It was found that during ATHT of the 7055 alloy, the solute atoms precipitated, grew, and redissolved as the temperature increased. When the temperature reached 200 °C, the hardness of the alloy increased sharply, and the electrical conductivity increased modestly. As the temperature was increased above 400 °C, the electrical conductivity of this alloy declined rapidly and the solute atoms in the alloy redissolved quickly. Meanwhile, the η'''' strengthening phase in the alloy gradually evolved into the η equilibrium phase. By analyzing the hardness and electrical conductivity curves, the temperature range of quenching sensitivity for the current alloy was 200-400 °C, which was consistent with the results measured by the traditional graded heat preservation method.
Key words: aluminum alloy; alternating temperature heat treatment; quenching sensitivity temperature range; microstructure evolution