Effect of Heavy Ion Irradiation on the Electrochemical Behavior of 321 Stainless Steel

Abstract

Aiming to the environment for 321 SS in the primary circuit of PWR, it is unclear how heavy ion irradiation affects the electrochemical behaivor of alloy. This work reveals that the corrosion resistances decrease in the order of 2 dpa > 0 dpa > 10 dpa > 60 dpa at room temperature, consistent with the sequence of δ-phase content near the surface. The optimal performance of the SS irradiated to 2 dpa is attributed to the highest Cr-rich δ-phase content. The pits occur in the C enrichment zone, accompanied by the increase of O content and the presence of a small amount of Si and Mn elements, while no pits occurred in the Ti enrichment area. The results provide a reference for the irradiated SS with heavy ion to acquire optimal pitting resistence.

Keywords: 321 SS；Heavy ion irradiatio；Electrochemical corrosion；Pitting；δ phase