ステンレス鋼における成分依存型粒界腐食機構

抄録

Intergranular corrosion (IGC) in stainless steels can be well explained by following two mechanisms; "Composition dependent IGC" and "Compound dependent IGC". In this paper, the composition dependent IGC mechanism was discussed. In this mechanism, it has been confirmed that IGC was induced only by the difference of corrosion rates at grainboundaries (GB) and the matrix, due to the change of the chemical composition of GB from that of the matrix.
The high concentration of P due to the GB segregation causes very severe IGC at active state corrosion potentials as in H₂SO₄ solution, where the Cr depleted zone never induces IGC. The Cr depleted zone is responsible for IGC in the passive state corrosion potential region as in most of standardized IGC test solutions, where only the high concentration of P at GB is not responsible for IGC.
In the next paper, the compound dependent IGC mechanism will be presented.