Estimation of stress intensity factor for corrosive environment

Abstract

Corrosion fatigue refers to the damage and failure of material under the combined action of cyclic stresses and corrosive environment, which affect the life of fatigue critical structures, such as, aero structures, submarine hulls, offshore structures etc. Several surveys have shown that 20-40 % of all engineering failures are due to corrosion fatigue [1]. The corrosive environment may be considered as a condition of enhanced crack growth rate (under constant stress intensity factor) or decrease in net ΔK to maintain the same crack growth rate. In the present investigation an attempt has been made to develop a model to correlate net ΔK with crack length and frequency. The developed model was validated using experimental data generated for 7475-T7351 alloy in aqueous solution of 3.5% NaCl. It is also noticed that the frequency significantly does affect the crack growth rate (constant ΔK) and the maximum crack growth rate is usually achieved at an intermediate frequency.