Environment-induced fatigue cracking behavior of aluminum alloys and modification methods

Abstract

AbstractThis paper reviews the current corrosion fatigue strength issues of light metals, which include the corrosion fatigue cracking behaviors, such as the prior-corrosion pit deformation mechanism, the synergistic interaction between prior-corrosion pits and local stress/strain, the coupling damage behavior under mechanical fatigue loading, and the surrounding environmental factors such as a high humidity and a current 3.5 wt.% or 5.0 wt.% NaCl aqueous solution. The characterization of corrosion fatigue crack growth rate based on simple and measurable parameters (crack propagation length and applied stress amplitude or stress intensity factor) is also of great concern in engineering application. In addition, an empirical model to predict S-N curves of aluminum alloys at the environmental conditions was proposed in this paper. One of the main aims was to outline the corrosion fatigue cracking mechanism, which favors the corrosion fatigue residual life prediction of aluminum alloys subjected to the different environmental media that are often encountered in engineering services. Subsequently, this paper explores recently various surface modification technologies to enhance corrosion fatigue resistance and to improve fatigue strength. For example, the fatigue strength of 2024-T4 aluminum alloy has been modified using plasma electrolytic oxidation coating with the impregnation of epoxy resin modification method to compare with other oxide coating or uncoated substrate alloy.