Effect of Retrogression Heat Treatment on Fatigue and Electrical Properties of 2024 Al alloy.
DOI:
https://doi.org/10.65568/gujes.2026.020201Keywords:
Retrogression and re-aging, Fatigue, Electrical conductivity, crack growth, StrengthAbstract
The fatigue behavior of 2024 aluminum alloy is strongly influenced by heat treatment conditions, particularly T6 and retrogression and re-ageing (RRA) processes. In this study, specimens obtained from 2024 alloy plates were solution heat-treated at 520°C /2 h and subsequently aged to the T4 condition at 120°C/24 h. All samples were then subjected to a natural ageing (shelf life) period of 15 days before undergoing retrogression at approximately 220°C/3 min, followed by re-ageing at 165°C for 2h. The heat treated samples were evaluated using tensile testing, electrical conductivity in %IACS and high cycle fatigue testing after all proposed heat treatment cycles. The samples were further tested under high-cycle fatigue conditions. The results indicate that both tensile properties and electrical conductivity were adversely affected after the 15-day shelf life. Distinct differences in fatigue behavior were observed between the retrogression and T6 (re-ageing) treated alloys. The retrogression treatment for a short time for the samples after 15 days, exhibited an improvement of mechanical strength and electrical conductivity. However, re-aging of these samples for 165/2hr shows a beak strength with decrease in electrical conductivity. Although, T6 condition provides superior strength, the Retrogression treatment offers a more favorable balance between strength and fatigue performance by improving crack growth resistance, making it a more suitable choice for applications requiring enhanced fatigue durability.
References
[1] Hatch, J.E.: Aluminum: Properties and Physical Metallurgy. ASM, Metals Park (1984)
[2] Heat Treatment of Wrought Aluminum Alloy Parts, Aerospace Material Specification, AMS 2770G, April, 2003
[3] F. Bahaideen, et.al, "Fatigue Behavior of Aluminum Alloy at Elevated Temperature", Modern Applied Science, April 2009.
[4] Xiao Li , ―Effect of thermal process on the mechanical properties of AA2024, AA2014 and AA2618 Al alloys, Oregon State University, MSC Thesis, 1993.
[5] D. A. P. Reis, et al., "Effect of artificial aging on the mechanical properties of an aerospace aluminum alloy 2024, Defect Diff.". Forum, 326–328, 193–198 (2012). D. A. P.
[6] G. İpek Selimoğlu, Merve Halimler, "The Retrogression and Re-Aging of AA2048", 19th International Metallurgy & Materials Congress, IMMC 2018, P 228-231.
[7] A. Meyveci, U. Caligulu, H. Durmuş, "Pin-on-disc characterization of 2xxx and 6xxx aluminium alloys aged by precipitation age hardening", Journal of Alloys and Compounds 491 (2010) 278–283.
[8] Ferrer, C.P., Koul, M.G., Connolly, B.J., Moran, A.L., "Improvements in Strength and Stress Corrosion Cracking Properties in Aluminum Alloy 7075 via Low-Temperature Retrogression and Re-Aging Heat Treatments", Corrosion, vol. 59, no. 6, June, 2003, pp.520-528.
[9] G. Akoz, B. Tuna, A. Kurban, "The Effect of Aging Time on Mechanical and Microstructural Properties in Precipitation Hardening of AA 2024 Aluminum Alloy", Kırşehir Ahi Evran Üniversitesi Fen Bilimleri Enstitüsü Dergisi (KUJINAS), 3(2), 2025, PP( 60-71).
[10] O. Olivira et.al., "Relationship between Electrical Conductivity and the Stage of the Heat Treatments of Aging and Overaging of AA2024" Materials Science Forum, Vol. 930, pp 400-404.
[11] S. Khangholi et.al., "Effect of Ag and Cu addition on the strength and electrical conductivity of Al-Mg-Si alloys using conventional and modified thermo-mechanical treatments".
[12] C. H. Gur, I. Yidiz, "Determining the Impact Toughness of Age-hardened AA2024 by Nondestructive Measurements" Divid Publishing 2004.
Downloads
Published
Issue
Section
License
Copyright (c) 2026 Gharyan University Journal of Engineering Science (GUJES)
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
