Effect of Cathodic Protection Potential on Corrosion Fatigue Crack Growth of a Duplex Stainless Steel in Synthetic Sea Water

Corrosion fatigue crack growth rate (da/dN) of (α+γ) dual-phase stainless steel SUS 329 J1 has been measured in synthetic sea water under free corrosion and the various cathodic potentials at a frequency of 0.17Hz. The effect of cathodic potential on da/dN as a function of ΔK was discussed in the range of ΔK≥20MPa·m1/2. The da/dN under the cathodic potential of -0.40--0.80V (Ag/AgCl) became much larger than that in open circuit. Cathodically polarized potential gave rise to the large acceleration of crack growth rate due to hydrogen embrittlement.