Fracture Toughness Assessment of 15Kh2NMFA-A Steel Based on Local Fracture Models

Experimental and computational methods to assess the fracture toughness of 15Kh2NMFA-A reactor vessel steel are analyzed based on the local fracture models: Rice–Tracey and developed in Pisarenko Institute of Problems of Strength of the National Academy of Sciences of Ukraine. The master curve was experimentally constructed, and parameters used in examined models were obtained. The Rice–Tracey model modification, which takes into account the averaging of the relative void radius in the vicinity of the crack tip, extending at each loading step, is shown to confirm a previously made assumption as to the fracture toughness assessment regardless of the finite element size near the crack tip. Since in the ductile-brittle transition region, the crack initiation is ductile, i.e., through void nucleation, growth, and coalescence, the fracture toughness assessment based on local ductile fracture models gained theoretical substantiation and demonstrated satisfactory agreement with experimental results.