Role of grain boundary segregation in corrosion fatigue process of high strength aluminium alloy

Effects of grain boundary segregation on fatigue crack growth in 7050 aluminium alloy have been investigated under various aging conditions in a humid air environment. The results show that with increased aging, the concentration of Mg segregation on the grain boundary decreases, resulting in a reduction in the fatigue crack growth rate for the same humidity and value of ΔK. The effect of grain boundary Mg segregation on the fracture stress has been calculated using the quasi-chemical method. The result indicates that Mg segregation induces fracture reduction and grain boundary embrittlement.