The Evaluation of Ductile-Brittle Transition Temperature Before and afterNeutron Irradiation in RPV Steels Using a Small Punch Test

摘要

A small punch (SP) test was performed to evaluate the ductile-brittle transition temperature before and afterrnneutron irradiation in reactor pressure vessel (RPV) steels produced by different manufacturing (refining) processes.rnThe results were compared to the standard transition temperature shifts from the Charpy test and Master Curve fracturerntoughness test in accordance with the ASTM standard E1921. The samples were taken from 1/4t location of the vesselrnthickness and machined into a 10x10x0.5mm dimension. Irradiation of the samples was carried out in the researchrnreactor at KAERI (HANARO) at about 290 ℃ of the different fluence levels respectively. SP tests were performed inrnthe temperature range of RT to -196℃ using a 2.4mm diameter ball. For the materials before and after irradiation, SPrntransition temperatures (TSP), which are determined at the middle of the upper and lower SP energies, showed a linearrncorrelation with the Charpy index temperature, T41J. Tsp from the irradiated samples was increased as the fluence levelrnincreased and was well within the deviation range of the unirradiated data. The TSP had a correlation with the referencerntemperature (T0) from the master curve method using a pre-cracked Charpy V-notched (PCVN) specimen.