Examining The Phase Formation of Aging and Shallow Cryogenic Process Applied to Aluminum Alloys with Thermal Analysis

Year 2024, Volume: 12 Issue: 1, 324 - 331, 25.03.2024

Gözde Altuntaş , Bulent Bostan

https://doi.org/10.29109/gujsc.1446429

Abstract

In this study, cryogenic treatment was applied to the 7*** series alloy, which is one of the aluminum alloys frequently used in the aviation and space industry, after the retrogression and re-aging process, and the phase formations were examined by thermal analysis. First of all, solution heat treatment was applied at 480 °C for 2 hours and water was given. After quenching, artificial aging heat treatment was applied at 120 °C for 24 hours. To start the RRA (retrogression and re-aging) heat treatment, after artificial aging, retrogression was performed at 200 °C for 10 minutes and quenched. Then, re-aging was performed at 120 °C for 24 hours and the aging process was completed. After the RRA heat treatment, cryogenic treatment was applied for 2 hours at -40 °C, -80 °C respectively. The heat treated samples were analyzed with a differential thermal analyzer and the transformations of GP, η′ and η phases were found. Since the η′ phase is known as the strength-increasing phase in the structure, the activation energies of each sample were calculated using the Augis-Bennet and Kissinger equations. The results showed that the activation energy of the sample treated with -40 cryogenic treatment was 50% less than the sample without cryogenic treatment. This situation proved with the Arrhenius equation that the formation of the η′ phase would be easier.

Keywords

7075 Al alloy, thermal analysis, cryogenic treatment, retrogression and re-aging

Supporting Institution

gazi üniversitesi BAP

Project Number

This study was supported by Gazi University scientific research projects number FGA-2024-9104. We would like to thank our university BAP coordinatorship.

Thanks

This study was supported by Gazi University scientific research projects number FGA-2024-9104. We would like to thank our university BAP coordinatorship.

References

• [1] Karakoca, Y. E., & AYTAÇ, A. (2022). Investigation of Drillability of CFRP/Al 7075 Stack. Mechanics, 28(6), 430-438.
• [2] Altuntaş, G., Altuntaş, O., & Bostan, B. (2021). Characterization of Al-7075/T651 alloy by RRA heat treatment and different pre-deformation effects. Transactions of the Indian Institute of Metals, 74, 3025-3033.
• [3] Altuntaş, G., & Bostan, B. (2022). Metallurgical characterization of natural aging effects on pre-deformed Al 7075/T651 alloy during retrogression and re-aging heat treatment. Kov. Mater, 60(4), 209-222.
• [4] Altuntaş, O. (2022). Enhancement of impact toughness properties of Al 7075 alloy via double aging heat treatment. Gazi University Journal of Science Part C: Design and Technology, 10(2), 195-202.
• [5] Mavi, A., Kaplan, Y., & Aksoz, S. (2021). Effects of aging and deep cryogenic treatment on wear behavior of Al7075 Alloy. Journal of Tribology, 143(12), 121702.
• [6] Ozer, M., Dalli, K., & Ozer, A. (2023). Effect of ball-burnishing on surface integrity and fatigue behaviour of 7175-T6 AA. Materials Science and Technology, 39(2), 248-257.
• [7] Ozer, M., Kaplan, Y., Ozer, A., & Aksoz, S. (2023). Influence of different sintering techniques on the wear properties of Al-15Si-2.5 Cu-0.5 Mg/B4C composites. Science of Sintering, (00), 60-60.
• [8] Cina, B. M., and Gan, R. (1974). Reducing the susceptibility of alloys, particularly aluminium alloys, to stress corrosion cracking. US patent, 3856584.
• [9] Holt, R. T., Rosario, V., & Durham, K. (1995). RRA Treatment of 7075-T6 Material from a CC130 Hercules Sloping Longeron. NRC/IAR Report LTR-ST-2021.
• [10] Park, J. K., & Ardell, A. J. (1984). Effect of retrogression and reaging treatments on the microstructure of Ai-7075-T651. Metallurgical and Materials Transactions A, 15, 1531-1543.
• [11] Danh, N. C., Rajan, K., & Wallace, W. (1983). A TEM study of microstructural changes during retrogression and reaging in 7075 aluminum. Metallurgical Transactions A, 14, 1843-1850.
• [12] Naeem, H. T., Ahmad, K. R., Mohammad, K. S., & Rahmat, A. (2014). Evolution of the retrogression and reaging treatment on microstructure and properties of aluminum alloy (Al-Zn-Mg-Cu). Advanced materials research, 925, 258-262.
• [13] Ohnishi, T., Ibaraki, Y., & Ito, T. (1989). Improvement of fracture toughness in 7475 aluminum alloy by the RRA (retrogression and re-aging) process. Materials transactions, JIM, 30(8), 601-607.
• [14] 57. Xu, X., Zhao, Y., Ma, B., & Zhang, M. (2015). Electropulsing induced evolution of grain-boundary precipitates without loss of strength in the 7075 Al alloy. Materials Characterization, 105, 90-94.
• [15] Khalfallah, A., Raho, A. A., Amzert, S., & Djemli, A. (2019). Precipitation kinetics of GP zones, metastable η′ phase and equilibrium η phase in Al− 5.46 wt.% Zn− 1.67 wt.% Mg alloy. Transactions of Nonferrous Metals Society of China, 29(2), 233-241.
• [16] Altuntaş, G., Özdemir, A. T., & Bostan, B. (2023). A survey of the effect of cryogenic treatment and natural ageing on structural changes and second-phase precipitation in Al–Zn–Mg–Cu alloy. Journal of Thermal Analysis and Calorimetry, 1-13.
• [17] Callister, W. D., and Rethwisch, D. G. (2011). Materials science and engineering (Vol. 5). NY: John Wiley and Sons.
• [18] Robinson J. S., Cudd R. L., Tanner D. A., Dolan G. P., Quench Sensitivity and Tensile Property Inhomogeneity in 7010 Forgings, Journal of Materials Processing Technology, 2001, 119, 261-267
• [19] Ferragut, R., Somoza, A., & Tolley, A. (1999). Microstructural evolution of 7012 alloy during the early stages of artificial ageing. Acta Materialia, 47(17), 4355-4364.
• [20] Berg, L. K., Gjønnes, J., Hansen, V. X., Li, X. Z., Knutson-Wedel, M., Schryvers, D., & Wallenberg, L. R. (2001). GP-zones in Al–Zn–Mg alloys and their role in artificial aging. Acta materialia, 49(17), 3443-3451.
• [21] Elder, J. P. (1985). The general applicability of the Kissinger equation in thermal analysis. Journal of thermal analysis, 30, 657-669.
• [22] Augis, J. A., & Bennett, J. E. (1978). Calculation of the Avrami parameters for heterogeneous solid state reactions using a modification of the Kissinger method. Journal of thermal analysis, 13, 283-292.
• [23] Sha, G., & Cerezo, A. (2004). Early-stage precipitation in Al–Zn–Mg–Cu alloy (7050). Acta materialia, 52(15), 4503-4516.
• [24] Karabulut, Ş., & Karakoç, H. (2017). Investigation of surface roughness in the milling of Al7075 and open-cell SiC foam composite and optimization of machining parameters. Neural Computing and Applications, 28, 313-327.
• [25] Khalfallah, A., Raho, A. A., Amzert, S., & Djemli, A. (2019). Precipitation kinetics of GP zones, metastable η′ phase and equilibrium η phase in Al− 5.46 wt.% Zn− 1.67 wt.% Mg alloy. Transactions of Nonferrous Metals Society of China, 29(2), 233-241.