Corrosion Behavior of Stainless Steels in Crevice under Cyclic Corrosion Test- Effect of Alloying Elements -

Abstract

Cyclic corrosion tests, consisting of 0.86 kmol･m^‒3 NaCl solution spraying, drying, and wetting process, were conducted using a crevice-structured spot-weld specimen of ferritic stainless steels in order to investigate the effect of alloying elements on the corrosion behavior. The addition of Ni to 18Cr1Mo ferritic stainless steels was the most effective in decreasing the maximum corrosion depth in the crevice. Mo was an effective alloying element and the increase of Cr was not effective. Ni and Mo acted as effective elements decreasing the critical passive current densities and the addition of Ni was the most effective in lowering repassivation pH in acidic NaCl aqueous solutions. The result that the maximum corrosion depth decreases remarkably in the crevice could be attributed to the benefitical effect of Ni that inhibit anodic dissolution and accelerate repassivation.