Effect of pre-corrosion on the fatigue behavior of AA7B04 and life forecast

The fatigue lives of 7B04-T6 aluminum alloys (AA7B04-T6) samples after corrosion in different environments were investigated. Corrosion pits resulting from different environments exhibited different morphologies and resulted in different fatigue lives. The environment conditions included a range of chloride concentrations (0.05–5% wt), electrolyte pH values (2–7), corrosion times (50–150 h), and temperatures (20–40 °C). An orthogonal test with four factors and three levels was designed. The order of impact of environment factors on the fatigue life are chloride concentration > corrosion time > temperature > electrolyte pH. The fatigue life of AA7B04 after corrosion was forecasted by measuring the corrosion current from potentiodynamic polarization curve testing. By entering the environment data, an expression for the fatigue life was obtained, which was validated using other conditions.