304ステンレス鋼の高温水中における粒界応力腐食割れ防止に及ぼす酸素酸イオンの影響

抄録

Effect of oxyanions such as MoO^2-₄, WO^2-₄, and CrO^2-₄ on the intergranular stress corrosion cracking (IGSCC) of Type 304 stainless steel in high temperature water was studied. The results obtained are as follows :
1) Addition of such oxyanion as MoO^2-₄, WO^2-₄, and CrO^2-₄ suppresses IGSCC of sensitized Type 304 stainless steel in high temperature nondeaerated water. The effectiveness of the inhibitive action by the oxyanion is ranked in the order of MoO^2-₄>WO^2-₄>CrO^2-₄.
2) The mechanism of IGSCC inhibition by MoO^2-₄ ion for sentized Type 304 stainless steel in high temperature water is considered as follows, i.e., the presence MoO^2-₄ ion decreases the dissolution rate of Cr depleted zone at grain boundaries to the level of matrix by helping the formation of the Cr rich film containing MoO₃ or adsorbed MoO^2-₄ ion on the surface of Type 304 stainless steel.