1989 年 40 巻 6 号 p. 762-765
It is well known that resistance of stainless steel to atmospheric corrosion is influenced by the surface finish, and this has been attributed to Cr depletion near the surface and changes in surface film composition.
There has, however, been little quantitative investigation of this phenomenon. The author has previously proposed a quick and easy electrochemical technique for measuring the depth profile of Cr near the surface of Fe-Cr and Fe-Cr-Ni alloys. In the present study, the depth profiles of Cr were measured by this method for SUS 304 stainless steel samples with various surface finishes. Accelerated atmospheric corrosion tests were also carried out to estimate the corrosion resistance of the various samples. These tests showed that the resistance to atmospheric corrosion changed in accordance with the Cr concentration at the surface of SUS 304 matrix. For example Cr concentration was 18.08% in the matrix, but was 15.7% with dry emery polishing and much rust formed on the surface. With wet emery polishing in 30% HNO3, however, it was 17.25% and virtually no rust formed.