Effects of Aging under Stress on Mechanical Properties and Microstructure of EN AW 7075 Alloy

Abstract

In the present study, microstructural and mechanical properties of EN AW 7075 following stress-aging were assessed. For this purpose, properties of stress-aged samples were compared with values obtained for conventionally aged counterparts. It is revealed that the strength and hardness of EN AW 7075 can be increased by the presence of external stresses during aging. Precipitation kinetics were found to be accelerated. The effects of conventional and stress-aging on the microstructure were analyzed using synergetic techniques: the differently aged samples were probed by differential scanning calorimetry (DSC) in order to characterize the precipitation processes. DSC was found to be an excellent screening tool for the analysis of precipitation processes during aging of this alloy with and without the presence of external stresses. Furthermore, using electron microscopy it was revealed that an improvement in mechanical properties can be correlated to changes in the morphologies and sizes of precipitates formed.

Low‐Cycle‐Fatigue Performance of Stress‐Aged EN AW‐7075 Alloy

“…The electron-transparent specimens and d) schematic highlighting the process (Reproduced under terms of the CC-BY license. [17] Copyright 2022, S.V. Sajadifar et al, published by Metals).…”

“…[15,16] Recently, novel thermomechanical treatments were employed to further improve the mechanical behavior of EN AW-7075 alloy. [12][13][14]17] Stress aging was found to be capable of enhancing the mechanical properties. [17,18] Previous studies showed that external stress or strains induced during aging considerably accelerate the precipitation kinetics, [17,18] as this approach can provide additional nucleation sites for precipitates.…”

“…[24] The precipitation process in Al alloys can successfully be analyzed in situ using differential scanning calorimetry (DSC) at various temperatures and scanning rates. [17,25] During heating of precipitation-hardened Al alloys in solution-heat-treated and quenched condition, second-phase particles are formed and dissolved according to the temperature changes. Dissolution and precipitation in Al alloys can be distinguished as endothermic and exothermic peaks, respectively.…”

“…Previously, DSC measurements confirmed that the enhancement in the strength of the EN AW-7075 alloy induced via aging under stress is connected to the increased fraction of strengthening η 0 precipitates formed. [17] Numerous components are subjected to cyclic loading while in service; hence, investigating the fatigue performance of parts is essential. Several studies concentrated on the fatigue performance of high-strength Al alloys.…”

Cooling rate as a process parameter in advanced roll forming to tailor microstructure, mechanical and corrosion properties of EN AW 7075 tubes

“…The T6 heat treatment, i. e. solution heat treatment followed by water quenching and subsequent artificial aging, can considerably enhance the strength of EN AW 7075 alloy [3]. Generally, the ultimate tensile strength of EN AW 7075 alloy in T6 condition was reported to be above 500 MPa, which is the highest value among the commercially available high-strength aluminum alloys [4][5][6][7]. In addition to the high ultimate tensile strength of this alloy, its acceptable formability in temperature-supported forming processes makes it a promising alternative for numerous engineering demands [8].…”