Abstract
The rational pre-stretching can contribute to obtaining better mechanical properties. This paper studies the effect of creep stain, mechanical properties, and microstructures of 7055 alloy under different pre-stretching conditions. The results show that compared with solid-quenched alloy, the 7055-T6 alloy is the optimal scheme to attain more creep strain, and the range of pre-stretching from 1.6% to 3.3% is suitable for creep-aged 7055-T6 alloy to obtain better mechanical properties. Further examination by TEM test shows that pre-stretching promotes the formation of dislocations, which provides superior nucleation regions for ή phase resulting in a higher strength alloy. Meanwhile, a unified creep-aging constitutive model for 7055-T6 alloy is established which can be used to accurately predict its creep behavior under the different pre-stretching.
Highlights
Aluminum alloy 7055, as a kind of Al-Zn-Mg-Cu alloy with higher alloy forming properties, exhibits better comprehensive performance such as high-strength, high-toughness, strong propagation ability of anti-fatigue crack, and good fracture toughness, is widely used in aeronautical structures such as aircraft wings [1]
For 7055 alloys in solid solution state in Figure 3a, it is worth noting that all creep-strain profiles show an increasing trend with the increase in stress
Micrographs of the un-stretched alloys pre-stretched) 7055 alloys and the microstructure evolution that occurs in creep-aging of the with states treated by the solutionizing and T6 treating before the creep-aging process
Summary
Aluminum alloy 7055, as a kind of Al-Zn-Mg-Cu alloy with higher alloy forming properties, exhibits better comprehensive performance such as high-strength, high-toughness, strong propagation ability of anti-fatigue crack, and good fracture toughness, is widely used in aeronautical structures such as aircraft wings [1]. Precise regulations of both deformed shape and material properties are very difficult due to the strong interactions between dislocations deriving from pre-strain and creep behavior in the CAF process. In this way, the influence of pre-straining level on the change in creep deformation and failure of 316H stainless steel has been investigated [9]. There is a huge scientific research value and engineering application significance to present the effect of mechanical properties and microstructures of creep-aged 7055 alloy under different pre-stretching conditions and its creep constitutive model with the pre-stretching conditions. This work was beneficial in choosing a reasonable range of pre-stretching, manufacture satisfying 7055 alloy materials and in promoting the wide application of the studied alloy
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