Effect of cold deformation before aging on microstructure and mechanical properties of Al-15Zn-0.5Mg-0.5Sc alloy

doi:10.13251/j.issn.0254-6051.2022.10.030

Abstract

Abstract: Solution-aging and solution-cold rolling-aging treatment were carried out for the hot rolled Al-15Zn-0.5Mg-0.5Sc alloy, and microstructure and mechanical properties of the alloy were studied by optical microscope, scanning electron microscope, transmission electron microscope and universal mechanical testing machine. The results show that cold rolling can decompose the saturated Al-Zn solid solution and dynamically precipitate Zn phase. At the same time, cold rolling also promotes the grain refinement and dislocation multiplication of the alloy. Artificial aging can lead to precipitation of high density η′ phase in the alloy. The high-density dislocations caused by cold rolling promote the precipitation process and accelerate the η′ phase transformation to η phase. Cold rolling before aging can obviously optimize the mechanical properties of the Al-15Zn-0.5Mg-0.5Sc alloy. After solution-cold rolling-artificial aging at 70 ℃, the yield strength and ultimate tensile strength of the Al-15Zn-0.5Mg-0.5Sc alloy are 413 MPa and 462 MPa, respectively. The strengthening mechanisms include fine grain strengthening, dislocation strengthening and precipitation strengthening. However, aging at 120 ℃ will accelerate dislocation annihilation and weaken the dislocation strengthening effect of the alloy.

Key words: Al-Zn alloy, cold deformation, heat treatment, microstructure, mechanical property

CLC Number:

TG146.21

Xiao Jijin, Liu Chongyu, Shi Lei, Sun Haoming, Zhang Lei. Effect of cold deformation before aging on microstructure and mechanical properties of Al-15Zn-0.5Mg-0.5Sc alloy[J]. Heat Treatment of Metals, 2022, 47(10): 179-184.

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