Effect of heat treatment on microstructure and mechanical properties of extruded Al-Zn-Mg-Cu alloy

doi:10.13251/j.issn.0254-6051.2020.05.029

Abstract

Abstract: The microstructure evolution and mechanical properties of Al-12Zn-2.4Mg-1.1Cu-0.3Zr-0.15Ni-0.12Mn (mass fraction, %) alloy under three different heat treatments were investigated by means of scanning microscope, hardness test, tensile test, and impact test. The results show that the microstructure of T6-treated alloy consists of α-Al matrix, η′ and η precipitation phases. The average microhardness and tensile strength of T6-treated alloy reach 210 HV and 597 MPa respectively, which are superior to that of T4-treated and T5-treatd alloy. The elongation of T6-treated alloy is slightly lower than that of T4-treated alloy because η′ and η precipitation phases have a certain mobility relative to the matrix which reduces the plasticity of the alloy. The impact fracture mechanism of T4-treated and T5-treatd alloy is brittle fracture. The impact property of T6-treated alloy is obviously improved and the fracture mechanism is ductile-brittle mixed fracture. T6 heat treatment should be adopted to the extruded Al-Zn-Mg-Cu alloy.

Key words: Al-Zn-Mg-Cu alloy, heat treatment, microstructure, mechanical properties

CLC Number:

TG146.2⁺1

Wei Di, Yang Li, Zhang Yaocheng, Lu Wangzhang, Pang Song, Zhi Yating. Effect of heat treatment on microstructure and mechanical properties of extruded Al-Zn-Mg-Cu alloy[J]. Heat Treatment of Metals, 2020, 45(5): 152-156.

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