In-Beam Stress Corrosion Behavior of Welded 308 Stainless Steel at 473 K in Aerated and Hydrogenated Water Conditions

Abstract

Stress corrosion tests were performed for welded 308 stainless steel under proton irradiation at 473 K in aerated water (DO: 0.150.22 ppm, DH: <10 ppb) and hydrogenated water (DH: 1.01.4 ppm, DO: <5 ppb) conditions. The in-beam loading condition was 0 and 300 MPa in tension under an irradiation dose rate of 1.3 © 10 ¹7 dpa/s. In situ measurement of electrochemical corrosion potential (ECP) and subsequent SEM analysis were also conducted for all the specimens. In the aerated water condition, the process of stress corrosion cracking (SCC) was significantly accelerated under irradiation, while the in-beam effect on SCC was suppressed in the hydrogenated water condition. The in-beam stress corrosion behavior is discussed in terms of both water radiolysis and radiation-induced microstructures.

Selective Dissolution of Delta Ferrite Phase in Welded 308 Stainless Steel under Proton Irradiation

“…3. In the in-beam corrosion tests conducted in the previous study 13) , the in situ ECP measurement con rmed a slight negative proportion of ECP during the tests. Although Cl − ions were not present in the aerated water solution at the inbeam corrosion tests, radiolytic products such as radical oxygens would act as electric charge carriers under irradiation.…”

“…The specimen examined by EBSD measurement was welded 308 stainless steel corroded at 0 MPa and 473 K for 2.16 × 10 5 s in aerated water conditions (DO: 0.15-0.22 ppm, DH: <10 ppb) under proton irradiation in the previous study 13) . The chemical composition of welded 308 stainless steel and the specimen preparation process for SCC tests are shown in Table 1 and Fig.…”

“…The total amount of dose level was estimated at 0.028 dpa for the inbeam specimen under a constant displacement damage rate of 1.3 × 10 −7 dpa/s. Details of the welding conditions, specimen preparation, in-beam stress corrosion apparatus, and ir- 13,14) . The in-beam corroded specimen was chemically cleansed by hydrochloric acid solution (35%, 200 ml) with pure water (200 ml) and hexamethylenetetramine (1.4 g) for 600 s at room temperature, and then mechanically polished by a choroidal silica suspension (powder diameter of 0.06 μm) for about 1800 s to a mirror nish for EBSD measurements.…”

“…In the previous study 13) , stress corrosion tests loaded at 0 and 300 MPa were conducted under 17 MeV proton irradiation for welded 308 stainless steel in aerated water condi-tions at 473 K. In situ measurement of electrochemical corrosion potential (ECP) and subsequent SEM analysis were also performed for all specimens. The process of SCC was signi cantly accelerated under irradiation, and the in-beam effect on SCC was discussed in terms of both water radiolysis and radiation-induced microstructures.…”