Fracture behavior of austenitic stainless steels irradiated in PWR

摘要

Fracture behavior of cold-worked 316 stainless steels irradiated up to 73 dpa in a pressurized water reactor was investigated by impact testing at -196, 30 and 150 degrees C, and by conventional tensile and slow tensile testing at 30 and 320 degrees C. In impact tests, brittle IG mode was dominant at -196 degrees C at doses higher than 11 dpa accompanying significant decrease in absorbed energy. The mixed IG mode, which was characterized by isolated grain facets in ductile dimples, appeared at 30 and 150 degrees C whereas the fracture occurred macroscopically in a ductile manner. The sensitivity to IG or mixed IG mode was more pronounced for higher dose and lower test temperature. In uniaxial tensile tests, IG mode at a slow strain rate appeared only at 320 degrees C whereas mixed IG mode appeared at both 30 and 320 degrees C at a fast strain rate. A compilation of the results and literature data suggested that IG fracture exists in two different conditions, low-temperature high-strain-rate (LTHR) and high-temperature low-strain-rate (HTLR) conditions. These two conditions for IG fracture likely correspond to two different deformation modes, twining and channeling. (C) 2008 Elsevier B.V. All rights reserved.