Fracture Toughness Evaluation of Reactor Pressure Vessel Steels by Master Curve Method Using Mini-CT Specimens

To examine the applicability of Mini-CT (0.16T-CT) specimens to fracture toughness evaluation by Master Curve method, we conducted fracture toughness tests using specimens with different size and shapes such as pre-cracked Charpy-type, 0.4T-CT and 1T-CT in addition to 0.16T-CT specimens for commercially manufactured five kinds of SA533B Cl.1 steels with different ductile-to-brittle transition temperature. Reference temperature T_o determined by 0.16T-CT specimens were approximately equal to those of 1T-CT specimens for all materials. The Weibull slope of 0.16T-CT specimens was similar to those of other larger specimens. We also examined a loading rate effect on T_o of 0.16T-CT specimens within the quasi-static loading range prescribed by ASTM E1921. There was no loading rate effect peculiar to 0.16T-CT specimens, while the higher loading rate gave rise to slightly higher T_o.