Research progress of the quenching characteristic of 7XXX (Al-Zn-Mg-Cu) aluminum alloy

The quenching characteristics and hardenability of 7XXX series (Al-Zn-Mg-Cu) aluminum alloys are reviewed. The hardenability of aluminum alloy is the property related to the quenching rate and the performance after quenching. By summarizing the mechanism of hardenability of aluminum alloys and the evaluation method of hardenability, we analyzed the factors affecting hardenability from the chemical composition, preparation process and microstructure of aluminum alloys. The results show that enhancing the hardenability is the key factor to obtain high-performance 7XXX series (Al-Zn-Mg-Cu) aluminum alloys. This paper introduces the research methods of hardenability of aluminum alloys, including the quenching-hardness testing method for determining the depth of aluminum alloy hardened layers, the isothermal aging-conducting method for determining the TTT curve of aluminum alloys, and the isothermal aging-mechanics for measuring TTP curves, performance test method, continuous cooling and phase change test method, to determine the curves of aluminum alloy CCT. In order to improve the hardenability of aluminum alloys, it is necessary to improve the aluminum alloy hardenability test methods.