Fatigue Characteristic Analysis of New ECO7175v1 Extruded Aluminum Alloy

Abstract

This paper investigates the fatigue characteristics of a new extruded aluminum 7175, with an experimental composition which uses a magnesium-calcium alloy during the alloying process instead of the standard pure magnesium. This new aluminum 7175, dubbed aluminum ECO7175v1, results in a cleaner manufacturing process and improves mechanical properties. The fatigue behavior of the new aluminum ECO7175v1 T74 temper is investigated. Experimental data show that the fatigue life of ECO7175v1-T74 aluminum can exceed 107 cycles with a fatigue strength of approximately 207 MPa, about 36% of its tensile strength. Fractography results show that failure modes are predominately ductile near the surface and brittle toward the center. In addition, at higher stresses, crack initiation points are typically at the surface of the specimens, compared with those at lower stresses. Irrespective of the stresses to which the specimens are subjected, all crack initiation points are located at the surface and no inclusions to act as stress concentrators are seen.