Prediction of corrosion fatigue lives of aluminium alloy on the basis of corrosion pit growth law

摘要

Tension-compression and rotating-bending fatigue tests were carried out using aluminium alloy 2024-T3, in 3% NaCl solution. The corrosion pit growth characteristics, and also the fatigue crack initiation and propagation behaviour were investigated in detail. The results obtained are summarized as follows: (i) Most of corrosion fatigue life (60-80%) is occupied with a period of corrosion pit growth at low-stress amplitude. The corrosion pit growth law can be expressed as functions of stress amplitude sigma(a) and an elapsed time t. (ii) The critical stress intensity factor for crack initiation from the corrosion pit was determined as 0.25 MPa root m. This value is the same as the threshold stress intensity factor range for crack propagation. (iii) Corrosion fatigue life can be estimated on the basis of corrosion pit growth law and crack propagation law. The estimated fatigue lives agree well with the experimental data.