Study on tensile and fracture properties of 7050-T7451 aluminum alloy based on material forming texture characteristics

Abstract

The 7050-T7451 aluminum alloy sheets after rolling show some texture features in three orthogonal directions, rolling direction (RD), transverse direction (TD) and normal direction (ND). After the rolled sheet is stretched, the inner crystal grains of the material are elongated in the stretching direction, forming a relatively obvious texture structure in the RD and TD. So there is obvious anisotropy in dynamic tensile properties in the three directions. In order to study its anisotropy, dynamic tensile test of aluminum alloy 7050-T7451 was carried out in the three directions. The strain rate of the test was 4000 s−1. Scanning electron microscopy (SEM) and electron back scattering diffraction (EBSD) direction imaging analysis were performed on the cross sections of specimens before and after tensile deformation. After the analysis of dynamic mechanical properties and microstructure morphology, it was found that texture was the main reason leading to anisotropy of dynamic mechanical properties of the material. After the dynamic tensile, the material was recrystallized and a fine secondary phase was produced, and then it shown the anisotropy in the tensile properties at different directions, in other words, shown to the obvious difference in the stress-strain curve of the dynamic tension. The ultimate tensile strength of TD direction was the largest and the ND is the smallest. The failure strain in RD was the largest and that in the ND was the smallest. The fracture surfaces in the three directions are all quasi cleavage fracture mixed of ductile fracture and cleavage brittle fracture. Transgranular fracture was obvious in ND direction, and intergranular fracture was obvious in RD and TD.