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The paper presents an investigation that was conducted to determine the possibility of the occurrence of the process of dynamic recrystallization in 2024 alloy during monotonic tensile and creep tests at the elevated temperatures of 100 °C, 200 °C, and 300 °C. As-extruded material was subjected to creep process with constant force at elevated temperatures, until two varying degrees of deformation were reached. After cooling at ambient temperature, the pre-deformed material was subjected to monotonic and fatigue tests as well as metallographic analysis. The process of dynamic recrystallization was determined in monotonic tests to occur at low strain rate (0.0015/s) only at the temperature of 300 °C. However, in the creep tests, this process occurred with varying efficiency, both during creep at 200 °C and 300 °C. Dynamic recrystallization was indicated to have a significant influence on the monotonic and cyclic properties of the material.

This paper presents results of monotonic tensile and creep tests conducted on typical Al-Cu-Mg alloy (commercial 2024) specimens. Tensile tests carried out at room (20 • C) and elevated (100 • C, 200 • C, 300 • C) temperatures made it possible to determine strength properties of the material (Young's modulus, yield stress, ultimate tensile strength). Creep tests were performed at elevated temperature (100 • C, 200 • C and 300 • C) with a constant force. In order to obtain material creep characteristics, creep-rupture tests were carried out. Then creep tests were conducted with two different strain values: one corresponding to the beginning of the secondary creep and the other corresponding to a certain value of the tertiary creep. After preliminary creep deformation at two various strain levels, specimens were cooled at ambient temperature and then subjected to monotonic tensile tests. The characteristics of the material were obtained for pre-strained specimens at different temperatures. Specimens fracture surfaces obtained as a result of tensile (at elevated and room temperature), creep and combined tests were analyzed.

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The paper is focused on creep-rupture tests of samples made of the 2024 alloy in the T3511 temper under uniaxial tensile stress conditions. The basic characteristics of the material at the temperatures of 100, 200 and 300 °C were determined, such as the Young’s modulus E, yield point σy, ultimate tensile strength σc and parameters K and n of the Ramberg–Osgood equation. Creep tests were performed for several different levels of nominal axial stress (load) at each temperature. It was observed that in the process of creep to failure at 200 and 300 °C, as the stress decreases, the creep time increases and, at the same time, the strain at rupture increases. However, such a regularity is maintained until a certain transition stress value σt is reached. Reducing the stress below this value results in a decreased value of the strain at rupture. A simple model of creep damage accumulation was proposed for the stress range above the transient value. In this model, the increase in the isotropic damage state variable was made dependent on the value of axial stress and the increase in plastic axial strain. Using the results of experimental creep-rupture tests and the failure condition, the parameters of the proposed model were determined. The surface of fractures obtained in the creep tests with the use of SEM technology was also analyzed.