Abstract
In this study, aluminum alloy 7010 was subjected to three different ageing treatments i.e., peak ageing (T6), over ageing (T7451) and retrogression and re-ageing (RRA) to study the influence of precipitate microstructure on the fatigue crack growth rate (FCGR) behavior. The microstructural modifications were studied by using TEM to examine the change in size and morphology of the precipitates. The size of the precipitates in the matrix range from 16–20 nm in T7451, 5–6 nm in RRA and 2–3 nm in T6 alloys, respectively. The FCGR tests were performed on standard compact tension (CT) specimens as per ASTM E647 standard in a computer controlled servo-hydraulic test machine with applied stress ratio, R = 0.1 and loading frequency of 10 Hz. The crack growth was measured by adopting compliance technique using a CMOD gauge attached to the CT specimen. The fatigue crack growth rate was higher in T7451 and lowest in RRA treated alloy. The RRA treated alloy showed higher ∆Kth compared to T7451 and T6 treated alloys. The measured ∆Kth was 11.1, 10.3 and 5.7 MPam½ in RRA, T6 and T7451 alloys, respectively. In the near-threshold regime, the RRA treated alloy exhibited nearly 2–3 times reduction in the crack growth rate compared to the T6 alloy. The growth rate in the RRA alloy was one order lower than that of the T7451 condition. The surface roughness of RRA treated alloy was more pronounced. The reduction in FCGR observed in RRA alloy was correlated to partial crack closure due to tortuous crack path and partially due to increased spacing between the matrix precipitates. The reduction in near-threshold FCGR and increase in ∆Kth is expected to benefit the damage tolerant capability of the aircraft structural components under service loads.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
ASTM E647-13a1.: Standard test method for measurement of fatigue crack growth rates. ASTM Intern., West Conshohocken, PA, 1–49 (2015)
Bai, S., Liu, Z., Gu, Y., Zhou, X., Zeng, S.: Microstructures and fatigue fracture behavior of an Al-Cu-Mg-Ag alloy with a low Cu/Mg ratio. Mater. Sci. Eng., A 530, 473–480 (2011)
Bai, S., Liu, Z., Li, Y., Hou, Y., Chen, X.: Microstructures and fatigue fracture behavior of an Al–Cu–Mg–Ag alloy with addition of rare earth Er. Mater. Sci. Eng., A 527(7–8), 1806–1814 (2010)
Borrego, L.P., Costa, J.M., Silva, S., Ferreira, J.M.: Microstructure dependent fatigue crack growth in aged hardened aluminium alloys. Int. J. Fatigue 26(12), 1321–1331 (2004)
Chen, X., Liu, Z., Lin, M., Ning, A., Zeng, S.: Enhanced fatigue crack propagation resistance in an Al-Zn-Mg-Cu alloy by retrogression and reaging treatment. J. Mater. Eng. Perform. 21(11), 2345–2353 (2012)
Cina, B.: Reducing the susceptiibility of alloys, particularly aluminium alloys, to stress corrosion cracking. US Patent 3856584 (1974)
Desmukh, M.N., Pandey, R.K., Mukhopadhyay, A.K.: Effect of aging treatments on the kinetics of fatigue crack growth in 7010 aluminum alloy. Mater. Sci. Eng., A 435–436, 318–326 (2006)
Fooladfar, H., Hashemi, B., Younesi, M.: The effect of the surface treating and high-temperature aging on the strength and SCC susceptibility of 7075 aluminum alloy. J. Mater. Eng. Perform. 19, 852–859 (2009)
Nandana, M.S., Udaya Bhat, K., Manjunatha, C.M.: Effect of retrogression heat treatment time on microstructure and mechanical properties of AA7010. J. Mater. Eng. Perform. 27(4), 1628–1634 (2018)
Rout, P.K., Ghosh, M.M., Ghosh, K.S.: Microstructural, mechanical and electrochemical behaviour of a 7017 Al-Zn-Mg alloy of different tempers. Mater. Charact. 104, 49–60 (2015)
Silva, G., Rivolta, B., Gerosa, R., Derudi, U.: Study of the SCC behavior of 7075 aluminum alloy after one-step aging at 163 & #xB0; C. J. Mater. Eng. Perform. 22, 210–214 (2012)
Wang, Y.L., Pan, Q.L., Wei, L.L., Li, B., Wang, Y.: Effect of retrogression and reaging treatment on the microstructure and fatigue crack growth behavior of 7050 aluminum alloy thick plate. Mater. Des. 55, 857–863 (2014)
Williams, J.C., Starke, E.A.: Progress in structural materials for aerospace systems. Acta Mater. 51, 5775–5799 (2003)
Xia, P., Liu, Z., Bai, S., Lu, L., Gao, L.: Enhanced fatigue crack propagation resistance in a superhigh strength Al–Zn–Mg–Cu alloy by modifying RRA treatment. Mater. Charact. 118, 438–445 (2016)
Acknowledgements
All the authors would like to thank the Director NITK and the Director CSIR-NAL for the support provided during the research work.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2020 Springer Nature Switzerland AG
About this paper
Cite this paper
Nandana, M.S., Udaya, B.K., Manjunatha, C.M. (2020). Influence of Heat Treatment on Near-Threshold Fatigue Crack Growth Behavior of High Strength Aluminum Alloy 7010. In: Niepokolczycki, A., Komorowski, J. (eds) ICAF 2019 – Structural Integrity in the Age of Additive Manufacturing. ICAF 2019. Lecture Notes in Mechanical Engineering. Springer, Cham. https://doi.org/10.1007/978-3-030-21503-3_35
Download citation
DOI: https://doi.org/10.1007/978-3-030-21503-3_35
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-030-21502-6
Online ISBN: 978-3-030-21503-3
eBook Packages: EngineeringEngineering (R0)