Effect of non-isothermal aging process on microstructure and properties of 7050 aluminum alloy

doi:10.13251/j.issn.0254-6051.2020.03.033

Abstract

Abstract:

Effects of different non-isothermal aging processes on the microstructure, fracture morphology and properties of 7050 aluminum alloy were studied by using TEM, SEM, Vickers hardness tester, electronic universal testing machine and eddy current conductivity tester, then the properties of the aged alloy were compared with that in T74 state. The results show that, after aging at 190 ℃, the main intracrystalline precipitation phase is η′ and the phase spacing is relatively large. The intragranular precipitates increase and the spacing decreases with the decrease of the aging temperature, and accompanied by secondary precipitation of needle-like precipitates. The precipitates at the grain boundary become coarser continuously, and tend to change from continuous to necklace-like to semi-continuous then to disconnected distribution, and the width of PFZ (precipitate-free zone) has little change. The hardness and tensile strength of the alloy increase first and then decrease, their peak values can be obtained when aged at 130 ℃. The conductivity of the alloy shows a monotonous upward trend and it tends to be stable when aged at 110 ℃. Compared with that in T74 state, the alloy can obtain a better comprehensive properties after solution treatment at (475+3) ℃ for 40 min and non-isothermal aging from 210 ℃ to 130 ℃ by a cooling rate of 20 ℃/h, with a reduction of the process time of 24 h.

Key words: non-isothermal aging, 7050 aluminum alloy, microstructure, properties

CLC Number:

TG156

Chen Geng, Miao Jingguo, Fang Qin, Sun Wenwen, Zhang Guangming, Wang Zhengyun. Effect of non-isothermal aging process on microstructure and properties of 7050 aluminum alloy[J]. HTM, 2020, 45(3): 169-173.

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