Influence of Loading Waveforms on Corrosion Fatigue Crack Growth for D36 Steel

The corrosion fatigue crack growth curves were measured under triangle, sinusoidal and square waveforms using gaps unilateral standard three-point bend specimens. The influence of loading waveforms on corrosion fatigue crack growth rate(CFCGR) for D36 steel was studied in natural seawater solution at different applied potentials. The results show that the CFCGR under sinusoidal waveform was the same as that under triangular waveform and was lower than the value under square waveform without cathodic protection. The acceleration of square waveform was more noticeable in the low stress intersity factor range. Under cathodic protection condition, the difference of the CFCGR between square waveform and sinusoidal waveform became wider. Whereas, the acceleration of square waveform on fatigue crack growth rate was reduced under anodic polarization condition.