Application of Miniature Specimens for Off-Center Tension Aimed at Determination of Fracture Toughness of Steels of VVER-1000 Reactor Vessel in the Ductile–Brittle Transition Zone

The article presents the results of testing miniature CT-0.16 specimens made from materials of the VVER-1000 reactor pressure vessel materials in both unirradiated and irradiated conditions, as well as after thermal aging, treated using the master curve method (ASTM E1921). A comparative analysis of the obtained transition temperatures T0 and results previously obtained for standard three-point bending of PCV specimens was conducted, showing a similarity of these values. An assessment of metal heterogeneity on the basis of the conducted tests according to the SINTAP procedure was carried out, indicating the need to increase the number of CT-0.16 specimens in the test series for the correct determination of the parameter T0. A conclusion was drawn regarding the prospects of using CT-0.16 type specimens for determining fracture toughness of reactor pressure vessel steels in conditions of limited volume of metal.