Estimation of Fracture Toughness for A508-III Steel in Ductile-to-Brittle Transition Region Using a Strain-Energy–Density-Based Fracture Failure Model

According to the assumption of intrinsic relationship between ultimate strain energy density and microcrack nucleation, this work developed a fracture failure model to estimate the fracture toughness of A508-III steel in the ductile-to-brittle transition region. The fracture toughness and uniaxial tension tests at different temperatures were carried out to determine the relationship between nucleation parameter and ultimate strain energy density, from which the evolutions of fracture toughness of A508-III ferritic steel for different cumulative failure probabilities at different temperatures were predicted. The fracture failure model can well describe the fracture toughness distribution of A508-III steel in the ductile-to-brittle transition region. Compared with the master curve method, this model has better temperature adaptability. It is more convenient to calibrate the parameters of this model compared with the traditional Beremin model, and without complex finite element analysis.