Enhanced Formability and Accelerated Precipitation Behavior of 7075 Al Alloy Extruded Rod by High Temperature Aging
Abstract
:1. Introduction
2. Experiment Procedure
3. Results and Discussion
3.1. The Microstructure of 7075 Aluminum Alloy Extruded Rod after Various Post-Process Heat Treatments (PPHTs)
3.2. Tensile Properties of 7075 Aluminum Alloy Extruded Rod after Various PPHTs at Room Temperature
3.3. The Tensile Fracture and the Working Hardness of PPHT Specimens
4. Conclusions
- High temperature aging can decrease precipitate hardening by the formation of an η phase.
- The high temperature aging at 280 °C, 12 h had fewer large particles (Al-Cu phase) in the Al matrix than full annealing did. The nucleation of microvoid and microcrack was located frequently around the large particles. The defects form cracks mainly and cause the fractures of the sample. Hence, the high temperature aging at 280 °C, 12 h presented to be superior over full annealing in regard to the work hardening rate and formability.
- High temperature aging can increase ductility only in a temperature range. At aging temperatures beyond 280 °C, the dissolution of η becomes endothermic, inducing natural aging and lower ductility.
Author Contributions
Funding
Conflicts of Interest
References
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Zn | Mg | Cu | Cr | Fe | Si | Al |
---|---|---|---|---|---|---|
5.80 | 2.53 | 1.64 | 0.23 | 0.09 | 0.05 | Bal. |
Symbol | Procedure |
---|---|
HTA240-8 | Heating at 490 ℃ for 1 h then quenching, and heating at 240 ℃ for 8 h and air cooling. |
HTA280-6 | Heating at 490 °C for 1 h then quenching, and heating at 280 ℃ for 6 h and air cooling. |
HTA280-12 | Heating at 490 °C for 1 h then quenching, and heating at 280 ℃ for 12 h and air cooling. |
HTA280-18 | Heating at 490 °C for 1 h then quenching, and heating at 280 ℃ for 18 h and air cooling. |
O | Heating at 415 °C for 2 h then furnace cooling at 20 ℃/h cooling rate to 230 ℃, holding for 6 h and furnace cooling. |
Al | Zn | Mg | Cu | |
---|---|---|---|---|
A | 59.4 | 0.6 | 21.0 | 19.0 |
B | 81.2 | 0.7 | 1.4 | 16.7 |
Al | Zn | Mg | Cu | |
---|---|---|---|---|
A | 87.7 | 0 | 1.1 | 11.2 |
B | 60.0 | 5.06 | 2.71 | 31.32 |
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Ku, M.-H.; Hung, F.-Y.; Lui, T.-S.; Lai, J.-J. Enhanced Formability and Accelerated Precipitation Behavior of 7075 Al Alloy Extruded Rod by High Temperature Aging. Metals 2018, 8, 648. https://doi.org/10.3390/met8080648
Ku M-H, Hung F-Y, Lui T-S, Lai J-J. Enhanced Formability and Accelerated Precipitation Behavior of 7075 Al Alloy Extruded Rod by High Temperature Aging. Metals. 2018; 8(8):648. https://doi.org/10.3390/met8080648
Chicago/Turabian StyleKu, Ming-Hsiang, Fei-Yi Hung, Truan-Sheng Lui, and Jyun-Jhih Lai. 2018. "Enhanced Formability and Accelerated Precipitation Behavior of 7075 Al Alloy Extruded Rod by High Temperature Aging" Metals 8, no. 8: 648. https://doi.org/10.3390/met8080648