MECHANISM OF CREVICE CORROSION AND ITS APPLICATION IN TESTING.

The mechanism of crevice corrosion in stainless steels was studied using an electrochemical technique. Experiments were based on the hypothesis that the rate of crevice corrosion could be determined by combining the crevice potential and the polarization curve in low pH high Cl** minus solutions, simulating the solution within the crevice. The rate of dissolution indicated by the polarization curve in 5M NaCl, pH 2, and the measured crevice potential was in good agreement with the corrosion rate obtained by immersion of the crevice specimen in neutral 3. 5% NaCl solutions. It is demonstrated that the electrochemical cell controlling crevice corrosion can be described quantitatively in terms of potentials inside and outside of the crevice, solution resistance in the crevice, and the polarization behavior in the crevice solution. The application of the results to crevice corrosion testing is also discussed.