Effect of Pre-Deformation on Microstructure and Mechanical Properties of Ultra-High Strength Al-Zn-Mg-Cu Alloy After Ageing Treatment
Received date: 2019-11-25
Revised date: 2020-03-26
Online published: 2020-04-09
Supported by
Defense Industrial Technology Development Program(JCKY2017205B032);National Natural Science Foundation of China(51971206)
Ultra-high strength Al-Zn-Mg-Cu alloy is a promising lightweight structural material, and there is still room to improve its mechanical property. As a typical precipitation strengthening material, controlling the size and distribution of precipitate is an effective way to enhance the mechanical properties of the ultra-high strength Al-Zn-Mg-Cu alloy. The influence of pre-deformation on the microstructures and properties of the ultra-high strength Al-Zn-Mg-Cu alloy after ageing treatment was studied by TEM, XRD, SEM, DSC and tensile tests. The microstructures and the tensile mechanical properties of Al-Zn-Mg-Cu alloy without pre-deformation and with 3% and 4% pre-deformation were compared. It is found that the pre-deformation can promote the ageing precipitation rate and enhance the precipitate density in the Al-Zn-Mg-Cu alloy, and the pre-deformation ratio of 3% can promote the dispersion of the precipitate phase in the grain interiors, but the pre-deformation ratio of 4% may result in coarsening of precipitate. The size of precipitate along the grain boundaries and the width of precipitation free zones decreased in the pre-deformation treated ultra-high strength Al-Zn-Mg-Cu alloys. The tensile strength and yield strength of the pre-deformation treated ultra-high strength Al-Zn-Mg-Cu alloys increased, and the elongation also increased slightly, in which the tensile strength and elongation of 3% pre-deformation alloy combined with 80 ℃ for 12 h and 120 ℃ for 8 h ageing were (813±4) MPa and 10.10%±0.77%, respectively. The results show that the dislocations produced by pre-deformation may provide more heterogeneous nucleation sites for the precipitate formation, and improve the precipitate's distribution.
Baoshuai HAN , Lijun WEI , Yanjin XU , Xiaoguang MA , Yafei LIU , Hongliang HOU . Effect of Pre-Deformation on Microstructure and Mechanical Properties of Ultra-High Strength Al-Zn-Mg-Cu Alloy After Ageing Treatment[J]. Acta Metall Sin, 2020 , 56(7) : 1007 -1014 . DOI: 10.11900/0412.1961.2019.00402
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