In-Beam Stress Corrosion Tests for Welded 308 Stainless Steel in Pure Water at 473 K

Abstract

Stress corrosion tests were performed for welded 308 stainless steel under proton irradiation at 473 K. The concentration of oxygen and hydrogen in the feed water was controlled to be below 5 and 10 ppb, respectively. The in-beam loading condition was 0 and 300 MPa in tension under an irradiation dose rate of 1.3 × 10−7 dpa/s. The electrochemical corrosion potential (ECP) was also measured during the tests. After the corrosion tests, the specimen surface at the fusion zone was examined by SEM for all specimens. Extensive electrochemical reactions on the specimen surface were implied by ECP measurement under the in-beam loading condition. The initiation of surface cracking followed by coalescence of numerous larger corrosion pits at the boundaries of ferrite phases in the austenitic matrix was detected for the in-beam specimens at 300 MPa. Thus, the initial process of stress corrosion cracking at weld metal would be accelerated under irradiation.