Experimental research on creep aging behavior of Al-Cu-Mg alloy with tensile and compressive stresses

Complex aircraft panels are generally manufactured by creep age forming process (CAF). In CAF, an aluminum panel is mainly subjected to bending, in which one side of the component is in tension and the other side is in compression. The tension and compression creep aging behaviors of Al-Cu-Mg alloy are investigated through creep tests, hardness tests and transmission electron microscope observations. It is found that the creep strains under compressive stresses are smaller than those under tensile stresses. When comparing to the microstructure of creep-aged alloy, the compressive stress can promote the formation of S phase in aluminum matrix and inhibit the generation of grain boundary precipitates, which leads to the improvement of hardness of the compression creep aged alloy. A unified creep constitutive model to describe the creep aging behavior of 2524 aluminum alloy with different stress roles was established based on the Hyperbolic Sine method, and a good agreement between the experimental results and model predictions is obtained.