Fracture toughness evaluation of reactor pressure vessel steels by master curve method using Mini-CT specimens

Tobita, Toru; Nishiyama, Yutaka ; Otsu, Takuyo; Udagawa, Makoto; Katsuyama, Jinya  ; Onizawa, Kunio 

Mini-CT (0.16T-CT) specimens up to eight can be taken from broken halves of surveillance Charpy specimens. We conducted a series of fracture toughness tests based on the Master curve method for several specimen size and shapes, such as 0.16T-CT, pre-cracked Charpy type, 0.4T-CT and 1T-CT specimens, in commercially manufactured 5 kinds of A533B class1 steels with different impurity contents and fracture toughness levels. Reference temperature To of 0.16T-CT specimens was approximately equal to those of 1T-CT and other type of specimens for all materials. We also examined a loading rate effect on TO of Mini-CT specimens for some materials within the specified range in the test method. Higher loading rate gave rise to slightly higher TO. The difference in TO between upper and lower loading rate of the standard was approximately 10C.