Effect of corrosion on the mechanical behaviour of aircraft aluminum alloys

Abstract

A brief overview of aircraft aluminum alloys, along with a discussion of their susceptibility to corrosion and the various types of corrosion damage is provided. The significance of the effect of corrosion on mechanical behaviour under static and fatigue loading conditions is demonstrated. For this purpose, experimental results concerning the tensile and fatigue behaviour of pre-corroded aluminum specimens are presented. The results, which are supported by metallographic observations, are discussed in terms of the synergetic effect of corrosion damage and corrosion-induced hydrogen embrittlement of the material. The fatigue crack growth and fracture behaviour of pre-corroded aluminum alloys is also examined. Experimental results demonstrate the essential influence of prior corrosion exposure on the material's damage tolerance performance. Corrosion, being a time-dependent and diffusion-controlled process degrades the material properties in a local scale. To describe the fracture behaviour of pre-corroded aluminum alloys, the concept of local fracture toughness is introduced. A mechanical model for assessing the local fracture toughness is presented and incorporated into a fatigue crack growth code for fatigue life assessment of pre-corroded material under irregular loading. © 2009 Woodhead Publishing Limited. All rights reserved.