Papers by Keyword: Subsize Specimen

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Authors: Michal Falcnik, Petr Novosad, Pavel Pesek, Mylos Kytka
Abstract: The advancement of proper methodology to determination of VVER reactor pressure vessel (RPV) materials transition behaviour has been followed. The project included selection of proper specimen geometries (standard 10x10x55 mm, sub-size 3x4x27 mm and 5x5x27.5 mm Charpy-V samples) and impact as well as dynamic fracture toughness testing. All the fundamental criterions have been applied to consider an applicability of small-sized specimens to Cr-Mo-V and Cr-Ni-Mo-V steel radiation embrittlement studies. Selected specimen geometries have been found to be fully valid for impact and dynamic fracture data and capable for prediction of standard specimen behaviour from the small specimens. Within testing of irradiated materials, it has been found not fully validity of all the compared transition temperatures.
Authors: Chang Sung Seok, Hyung Ick Kim, Dae Jin Kim, Bong Kook Bae, Sang Pil Kim
Abstract: When huge energy transfer systems like nuclear power plants and steam power plants are operated for long times at high temperatures, mechanical properties change and ductile-brittle transition temperature increases by degradation. So we must estimate the degradation in order to assess safety, life expectancy, and other operation parameters. The sub-sized specimen test method using the surveillance specimen, and BI (Ball Indentation) method were developed for evaluating the integrity of metallic components. In this study, we will present the evaluation of the ductile-brittle transition temperature using the BI test and the sub-sized specimen test. The four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method. The tensile test, the fracture toughness test, and the BI test were performed. The results of the fracture toughness tests using the sub-sized specimens were compared with those of the BI test. The evaluation technique of the ductile-brittle transition temperature using the BI test was also discussed. Our results show that the ductile-brittle transition temperatures rose as the aging time increased. We suggested that the fracture toughness results of the sub-sized specimen test and the IEF results of the BI test could be used in the estimation of the ductile-brittle transition temperature as material degrades.
Authors: Hyung Ick Kim, Yong Huh, Jae Sil Park, Chang Sung Seok
Abstract: The safety and reliability of industrial machineries and structures used in various, and severe conditions has become an increasing concern. This study proposes ductile-brittle transition temperature (DBTT) evaluation technique by the sub-sized specimen test to prevent cleavage fracture. Four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared. The fracture toughness tests were performed on sub-sized specimens both at room and low temperatures. The results of the fracture toughness tests were analyzed to obtain the DBT behaviours of the specimen materials
Authors: Hyung Seop Shin, Dong Kyun Ko, Young Jin Jung, Sang Yeob Oh, Jung Ho Ahn
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