Calibration of three-parameter Weibull stress model for 15Kh2NMFA RPV steel

Weibull stress model represents a basic local approach model used in the ductile-to-brittle transition region for description and prediction of cleavage fracture for materials of both PWR and WWER reactor pressure vessels. In the Weibull stress model used most frequently until now [1], the parameters are determined by a calibration procedure using the fracture toughness values of high and low constraint specimens. In the present paper, the results of SEN(B) pre-cracked specimens of 10 × 20 × 120 mm size, with deep and shallow cracks, are utilized. Specimens were made of material of WWER-1000 reactor pressure vessel, and were tested at Nuclear Research Institute Rez. Determination of Weibull stress was performed for both the case of including plastic strain correction into the Weibull stress formula and without it.