LCF behavior of 2024AA under uni- and biaxial loading taking into account creep pre-deformation

Abstract

This study presents the results of experimental low-cycle fatigue (LCF) tests of aluminum 2024 alloy T3511 temper in uni- and biaxial loading states. Tests were carried out on both the as-received material (hardened extruded rods) and material with different pre-deformation histories. These deformations were carried out in the creep process at 200 °C and 300 °C for two different levels of at each temperature. The pre-deformed material’s basic fatigue characteristics were determined and compared with the appropriate characteristics of the as-received material. In-depth macro- and microscopic analysis (SEM) of fracture surfaces was done. The effect of preliminary creep on LCF behavior of investigated alloy was characterized for both uni- and biaxial loading. An increase of fatigue life occurs for large plastic strains in the case of cyclic tension/compression. For in-phase biaxial loading, improvement of life is observed only for material with pre-deformation at 300 °C. Crack initiates in the plane of maximum shear strains for both biaxial loading and pure torsion. For tension/compression – in the plane of maximum principal stress (strain).