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Effect of pre-deformation on quench-induced inhomogeneity of microstructure and hardness in 7050 aluminum alloy

2019; Elsevier BV; Volume: 158; Linguagem: Inglês

10.1016/j.matchar.2019.110005

1873-4189

X.W. Yu, J.H. Chen, J.Y. Li, Cuilan Wu, Xiaorong Yang,

Microstructure and Mechanical Properties of Steels

7xxx aluminum alloys usually have high quenching sensitivity, which results in the inhomogeneous microstructure and mechanical properties of large-size components. The effect of pre-deformation on the quench-induced inhomogeneity of the microstructure and properties in a high strength 7050 aluminum alloy was investigated by means of the end-quenching technique, transmission electron microscopy (TEM) and three-dimensional electron tomography (3DET). The size of the η′ precipitates and quench-induced precipitates (QP) and the width of the grain boundary (GB) precipitate-free zones (PFZ) increased with the decrease of the quenching rate, leading to a decrease in hardness along the long axial direction of the end-quenching sample. However, after introducing 20% pre-deformation, the PFZ around the GB and QP in the slow-cooled end of the aged samples was significantly reduced, and dispersive η′ precipitates were formed around the GB and QP instead, which greatly improved the strength of the slow-cooled end. Compared with the sample without pre-deformation, the introduction of 20% pre-deformation increased the hardness of the slow-cooled end by 30% without obviously reducing the hardness of the water-quenched end, which means that the 20% pre-deformation effectively reduced the hardness inhomogeneity of the 7050 aluminum alloy. This work provides a new method for reducing the quench-induced inhomogeneity of aluminum alloys.