In-situ corrosion fatigue performance and fracture mechanism of aviation aluminum alloy

Abstract

In order to study the fatigue properties of 2024 aluminum alloy under different corrosion fatigue conditions, First, an in-situ corrosion fatigue platform was established, and then non-corrosion fatigue test, pre-corrosion fatigue test and in-situ corrosion fatigue test were used to comparatively study the fatigue life and fracture mechanism of 2024 aluminum alloy. Scanning electron microscopy(SEM) was used to characterize the macro and micro fracture characteristics and explore the failure mechanism. The results show that the samples with the same corrosion environment and corrosion time, the fatigue life in in-situ corrosion fatigue test and in pre-corrosion fatigue test is 92% and 42% of corrosion fatigue life, respectively. Under the condition of in-situ corrosion fatigue, the squeeze and the extrusion of slip zone leads to the increase of surface roughness, which adsorbs more corrosive medium, exacerbates pit evolution, accelerates the initiation of crack and forms multiple crack sources. The connection of cracks forms a larger size of damage, and rapidly expands inside the material. A lot of brittle fringes are observed in the fracture of the pre-corrosion and in-situ corrosion fatigue test specimens, and the average distance between the fringes under in-situ corrosion fatigue is about two times larger than that under non-corrosion fatigue, indicating the crack propagation rate is faster under the in-situ corrosion fatigue condition.

Keywords

• aviation aluminum alloy
• in-situ corrosion fatigue
• fatigue life
• fracture mechanism