Evaluation of charpy impact properties and fracture toughness for irradiated ferritic steels (3)

not registered

Four kinds of ferritic steels, 61FK, 61FS, ASTM A213T9 (F9S) and NSCR9, were irradiated in SMIR-10 at 823 K to (3.2-9.0)10 n/m (E 0.1 MeV) and subjected to instrumented Charpy impact tests. The absorbed energy, dynamic yield and maximum loads, brittle fracture load and the deflection to brittle fracture were measured as a function of test temperature and ductile-to-brittle transition temperature (DBTT) and the upper shelf energy (USE) were evaluated. For the test, Charpy V-notch specimens, JIS-4, were used which had the dimensions of 10 2 55 mm and V-notch geometry of notch root radius of 0.25㎜, notch depth of 2 mm and notch angle of 45 degrees. Main results obtained are as follows. (1)The DBTT was less dependent on neutron dose. The DBTT for the higher dose of (8.8-9.0)10 n/m increased in th order of 61FK, NSCR9, 61FS and F9S. (2)As the neutron dose increased, the USE decreased for 61FK, while it stayed almost constant for 61GS and increased for F9S. The USE for the higher dose decreased in the order of 61FK, NSCR9, 61FS and F9S, which was the same as the increasing order of DBTT. (3)The DBTT shifts, DBTT, due to irradiation with the higher dose level increased in the order of 61FK, 61FS and NSCR9, except for F9S, where the DBTT in the unirradiated state is not available, (4)The change in USE, USE, due to irradiation with the higher dose increased in the order of 61FS, 61FK and NSCR9, except for F9S. (5)Comparison of the present results with the previous ones irradiated at 723K in SMIR-10 showed that 823K irradiation caused considerably larger embrittlement than 723K irradiation, especially for F9S and 61FK.