2013 Volume 62 Issue 7 Pages 259-266
In order to clarify the influence of sulfur content on the pitting corrosion behavior of surface, L-section （longitudinal section）and T-section（transverse section）of stainless steel plate, cyclic corrosion test（CCT）and anodic polarization measurement in 0.85 M NaCl aqueous solution have conducted. Thick plate specimens （t 25 mm）of type 304 stainless steels containing 7, 29 and 57 ppm S were subjected to these tests. In CCT, rusting was more significant over T-section than surface and L-section. However, the number of initial rust spots over the T-section decreased with a reduction of S content. In pH 7 solution, the pitting potential（Epit）for 57 ppm S specimen was less noble at T-section than surface and L-section. But Epit at the T-section was shifted toward noble side with a reduction of S content. On the other hand, in pH 1 solution, Epit was low value regardless of S content. Furthermore, the cross-sectional shape of pits originated from MnS inclusion at the T-section was investigated. The MnS inclusion stretched into the steel matrix along the rolling direction and the growth of pitting corrosion along the MnS inclusion were observed.