EFFECT OF POTENTIAL ON THE CORROSION FATIGUE CRACK GROWTH RATE IN AISI 304 STAINLESS STEEL IN SODIUM SULFATE SOLUTION AT 250 C.

The corrosion fatigue crack growth (FCG) behavior of sensitized AlSl 304 stainless steel was studied in 0. 01M Na//2SO//4 solution at 250 C. Crack growth rates at different frequencies ranging from 1. 0 to 8 multiplied by 10** minus **3 Hz and at different electrochemical potentials were measured with a sinusoidal loading waveform at a load ratio of 0. 5. The results show that the FCG rate and fracture morphology depend on frequency and applied potential. At low frequencies (below 8 multiplied by 10** minus **2 Hz), there is a critical potential (between minus 450 and minus 200 mV//H) above which the FCG rates are enhanced over those observed at lower potentials. Fracture morphology depends on potential as well as frequency. At low potentials and/or higher frequencies, transgranular cracking is the principal mode of failure; however, at high potentials and/or at low frequencies, fatigue cracks propagate intergranularly.