Effects of two-stage creep-aging processing on mechanical properties of an Al–Cu–Mg alloy

•Two-stage creep-aging behaviors of an Al–Cu–Mg alloy are achieved.•Two-stage creep-aging processing of an Al–Cu–Mg alloy greatly improves its mechanical properties.•In particular, increasing the second stage creep-aging temperature enhances the yield strength.•The yield stress decreases, whilst the ultimate tensile strength and elongation first increase then decrease with increasing external stress applied during creep-ageing.

Two-stage creep-aging behavior of an Al–Cu–Mg alloy are studied by uniaxial tensile creep tests over wide ranges of temperature and external stress. Effects of creep-aging temperature and external stress on mechanical properties are discussed. It is found that the mechanical properties of the studied Al–Cu–Mg alloy are strongly sensitive to the creep-aging parameters. The two-stage creep-aging processing can change the characteristics of aging precipitates and dislocations, which greatly affects the mechanical properties of the studied Al–Cu–Mg alloy. With the increase of the second stage creep-aging temperature, the yield strength increases, while the ultimate tensile strength and elongation decrease. Meanwhile, the yield strength decreases with the increase of external stress. However, the ultimate tensile strength and elongation first increase and then decrease when the external stress is continuously increased within the tested conditions. Additionally, the mechanical properties of the two-stage creep-aged alloy are better than those of one-stage creep-aged and stress-free aged alloys.

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