高クロム-フェライト鋼の耐食性に及ぼす475°C脆化処理の影響

抄録

Influence of 475°C embrittlement of high-Cr ferritic steels on their corrosion resistances was investigated mainly by potentiostatic method. The results obtained are summarized as follows: (1) Materials aged at 475°C do not lose in the corrosion resistance in active state and have a tendency to gain it more than the annealed materials. (2) The Flade potential of materials aged at 475°C is less noble by 0.1 to 0.15 V than that of the annealed materials. The critical current density for passivation is decreased by aging treatment 475°C. (3) The resistance to intergranular corrosion is decreased by aging treatment at 475°C. (4) In over-passive state, the anodic current has a tendency to decrease by aging treatment and a secondary passive state is clearly observed. (5) These changes are observed most clearly at 475°C and are apparent in proportion to the length of aging time at 475°C. (6) These corrosion behaviors of 475°C aging materials can be well explained by postulating a Fe₃Cr-type superlattice.