Experimental study of the low-cycle fatigue life under multiaxial loading of aluminum alloy EN AW-2024-T3 at elevated temperatures

This paper presents the results of an experimental study conducted on technical aluminum alloy EN AW-2024-T3 specimens under multiaxial low-cycle-fatigue loading at elevated temperatures. An original experimental setup, consisting of a biaxial servo-hydraulic MTS 858 MiniBionix material testing system, Maytec resistance furnace, high-temperature MTS extensometer and hydraulic grips of original design, was used in tests. Tubular specimens were subjected to multiaxial fatigue loading, proportional and non-proportional (with phase shift), under isothermal conditions of the air atmosphere. Multiaxial tests were performed under combined axial-torsional loading. Fractography analysis were conducted on the tested samples, and crack initiation mechanism under conditions of multiaxial loads at elevated temperatures were identified. Obtained fatigue life values were analyzed, particularly from the perspective of the possibility of approximating them by means of simple relations.