Effect of solid solution time on microstructure and crushing performance of Al-5.7Zn-0.7Mg aluminum alloy profiles

doi:10.13251/j.issn.0254-6051.2021.10.017

Abstract

Abstract: Solid solution treatment at 470 ℃for different time and two-stage aging treatment for Al-5.7Zn-0.7Mg aluminum alloy thin-walled profiles were carried out to investigate the effects of grain microstructure and recrystallisation on the crushing performance such as average load (F_m), peak load (F_p), energy absorption (U) by means of optical microscopy (OM), electron backscattered diffraction (EBSD), quasi-static axial crushing test and room temperature tensile test, and the characteristics of crushing deformation and the causes of cracking of the alloy were studied. The results show that the recrystallization degree of the aluminum alloy profiles increases with the solution time increasing, while the strength decreases gradually, and the peak load, energy absorption and average load of the aluminum alloy thin-walled beam also decreases gradually. The peak load and absorbed energy of the aluminum alloy profiles after online water quenching are 406 kN and 33.3 kJ, respectively. After solid solution treated for 120 min, the peak load and energy absorption are 359 kN and 30.7 kJ, which reduced by 11.5% and 8% compared with onhine water quenching, respectively. When solid solution for a long time, the recrystallization degree of the aluminum alloy profiles increases significantly, and the recrystallized grains are generally with large-angle grain boundaries along which the cracks are more likely to propagate, and the specimens are more likely to crack.

Key words: aluminum alloy, grain microstructure, quasi-static axial crushing, absorbed energy, crack propagation mode

CLC Number:

TG146.2

Pan Renjie, Chen Kangmin, Guo Hui, Fan Shitong. Effect of solid solution time on microstructure and crushing performance of Al-5.7Zn-0.7Mg aluminum alloy profiles[J]. Heat Treatment of Metals, 2021, 46(10): 101-107.

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