Abstract
The effects of retrogression and re-aging (RRA) treatment on intergranular corrosion (IGC), exfoliation corrosion (EXCO), stress corrosion cracking (SCC) behavior and microstructure of spray formed Al-7075 were investigated by a scanning electron microscope, a transmission electron microscope, slow strain rate test, and EXCO and IGC test. The results show that the precipitates are redissolved in the matrix of the alloy after retrogression at 200 °C for a suitable time (8 min), and the grain boundary precipitates are discrete and the obvious precipitate free zones are left at the grain boundaries. After RRA with suitable retrogressed time, thin homogeneous dispersive precipitates are separated out again in the matrix. After retrogression at 200 °C for 8 min and re-aging, the ultimate tensile strength, elongation, IGC depth, EXCO rating, and SCC index of spray formed Al-7075 are 791 MPa, 8.5%, 29.8 μm, EA, and 0.155, respectively.
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T. Hu, K. Ma, T.D. Topping, J.M. Schoenung, and E.J. Lavernia: Precipitation phenomena in an ultrafine-grained Al alloy. Acta Mater. 61, 2163–2178 (2013).
K. Ma, H. Wen, T. Hu, T.D. Topping, D. Isheim, D.N. Seidman, E.J. Lavernia, and J.M. Schoenung: Mechanical behavior and strengthening mechanisms in ultrafine grain precipitation-strengthened aluminum alloy. Acta Mater. 62, 141–155 (2014).
S.L. George and R.D. Knutsen: Composition segregation in semi-solid metal cast AA7075 aluminium alloy. J. Mater. Sci. 47, 4716–4725 (2012).
T. Marlaud, A. Deschamps, F. Bley, W. Lefebvre, and B. Baroux: Influence of alloy composition and heat treatment on precipitate composition in Al–Zn–Mg–Cu alloys. Acta Mater. 58, 248–260 (2010).
M. Jeyakumar, S. Kumar, and G.S. Gupta: Microstructure and properties of the spray-formed and extruded 7075 Al alloy. Mater. Manuf. Processes 25, 777–785 (2010).
M. Jeyakumar, S. Kumar, and G.S. Gupta: The influence of processing parameters on characteristics of an aluminum alloy spray deposition. Mater. Manuf. Processes 24, 693–699 (2009).
R.M. Su, Y.D. Qu, J.H. You, and R.D. Li: Study on a new retrogression and re-aging treatment of spray formed Al–Zn–Mg–Cu alloy. J. Mater. Res. 31, 573–579 (2016).
J.L. Shi, H.G. Yan, B. Su, J.H. Chen, S.Q. Zhu, and G. Chen: Preparation of a functionally gradient aluminum alloy metal matrix composite using the technique of spray deposition. Mater. Manuf. Processes 26, 1236–1241 (2011).
R.E. Ricker, E.U. Lee, R. Taylor, C. Lei, B. Pregger, and E. Lipnickas: Chloride ion activity and susceptibility of Al alloys 7075-T6 and 5083-H131 to stress corrosion cracking. Metall. Mater. Trans. A 44, 1353–1364 (2013).
S. Rajakumar and V. Balasubramanian: Predicting grain size, and tensile strength of friction stir welded joints of AA7075-T6 aluminium alloy. Mater. Manuf. Processes 27, 78–83 (2012).
G. Silva, B. Rivolta, R. Gerosa, and U. Derudi: Study of the SCC behavior of 7075 aluminum alloy after one-step aging at 163 °C. J. Mater. Eng. Perform. 22, 210–214 (2013).
E.M. Arnold, J.J. Schubbe, P.J. Moran, and R.A. Bayles: Comparison of SCC thresholds and environmentally assisted cracking in 7050-T7451 aluminum plate. J. Mater. Eng. Perform. 21, 2480–2486 (2012).
H. Fooladfar, B. Hasnemi, and M. Younesi: 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 (2010).
M.J. Starink and S.C. Wang: A model for the yield strength of overaged Al–Zn–Mg–Cu alloys. Acta Mater. 51, 5131–5150 (2003).
D. Wang, D.R. Ni, and Z.Y. Ma: Effect of pre-strain and two-step aging on microstructure and stress corrosion cracking of 7050 alloy. Mater. Sci. Eng., A 494, 360–366 (2008).
B.M. Cina: Reducing the susceptibility of alloys, particularly aluminium alloys, to stress corrosion cracking. U.S. Patent No. 3.856.584, December 24, 1974.
G. Peng, K. Chen, S. Chen, and H. Fang: Influence of repetitious-RRA treatment on the strength and SCC resistance of Al–Zn–Mg–Cu alloy. Mater. Sci. Eng., A 528, 4014–4018 (2011).
Y. Reda, R. Abdel-Karim, and I. Elmahallawi: Improvements in mechanical and stress corrosion cracking properties in Al-alloy 7075 via retrogression and reaging. Mater. Sci. Eng., A 485, 468–475 (2008).
R.M. Su, Y.D. Qu, and R.D. Li: Effect of aging treatments on the mechanical and corrosive behaviors of spray-formed 7075 alloy. J. Mater. Eng. Perform. 23, 3842–3848 (2014).
R.M. Su, Y.D. Qu, J.H. You, and R.D. Li: Study on microstructure, mechanical properties and corrosion behavior of spray formed 7075 alloy. Mater. Today Commun. 4, 109–115 (2015).
T. Ohnishi, Y. Ibaraki, and T. Ito: Improvement of fracture toughness in 7475 aluminum alloy by the RRA (retrogression and re-aging) process. Mater. Trans. JIM 30, 601–607 (1989).
A.F. Oliveira, Jr., M.C. De Barros, K.R. Cardoso, and D.N. Travessa: The effect of RRA on the strength and SCC resistance on AA7050 and AA7150 aluminium alloys. Mater. Sci. Eng., A 379, 321–326 (2004).
T. Marlaud, A. Deschamps, F. Bley, W. Lefebvre, and B. Baroux: Evolution of precipitate microstructures during the retrogression and re-ageing heat treatment of an Al–Zn–Mg–Cu alloy. Acta Mater. 58, 4814–4826 (2010).
X.J. Wu, M.D. Raizenne, R.T. Holt, C. Poon, and W. Walllace: Thirty years of retrogression and re-aging (RRA). Can. Aeronaut. Space J. 47, 131–138 (2001).
P. Bai, X. Hou, X. Zhang, C. Zhao, and Y. Xing: Microstructure and mechanical properties of a large billet of spray formed Al–Zn–Mg–Cu alloy with high Zn content. Mater. Sci. Eng., A 508, 23–27 (2009).
E. Salamci: Ageing behaviour of spray cast Al–Zn–Mg–Cu alloys. Turk. J. Eng. Environ. Sci. 25, 681–686 (2001).
E. Salamci: Mechanical properties of spray cast 7XXX series aluminum alloys. Turk. J. Eng. Environ. Sci. 26, 345–352 (2002).
G. Sha and A. Cerezo: Early-stage precipitation in Al–Zn–Mg–Cu alloy (7050). Acta Mater. 52, 4503–4516 (2004).
L.K. Berg, J. Gjønnes, V. Hansen, X.Z. Li, M. Knutson-Wedel, G. Waterloo, D. Schryvers, and L.R. Wallenberg: GP-zones in Al–Zn–Mg alloys and their role in artificial aging. Acta Mater. 49, 3443–3451 (2001).
H. Jiang and R.G. Faulkner: Modelling of grain boundary segregation, precipitation and precipitate-free zones of high strength aluminium alloys—I. The model. Acta Mater. 44, 1857–1864 (1996).
H. Jiang and R.G. Faulkner: Modelling of grain boundary segregation, precipitation and precipitate-free zones of high strength aluminium alloys—II. Application of the models. Acta Mater. 44, 1865–1871 (1996).
ACKNOWLEDGMENTS
This research was financially supported by the National Natural Science Foundation of China (51574167), China Postdoctoral Science Foundation (2016M601334), Program for Innovative Research Team in University of Liaoning Province (LT2015020), and Science and Technology Program of Liaoning Provincial Department of Education (LGD2016003).
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Su, R., Su, J., Qu, Y. et al. Retrogression on corrosion behavior of spray formed Al-7075. Journal of Materials Research 32, 2621–2627 (2017). https://doi.org/10.1557/jmr.2017.220
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DOI: https://doi.org/10.1557/jmr.2017.220