Prediction of Characteristic Length and Fracture Toughness in Ductile-Brittle Transition Available to Purchase

Finite element method was used to analyze the three-point bend experimental data of A533B-1 pressure vessel steel obtained by Sherry, Lidbury, and Beardsmore [1] from −160 to −45 °C within the ductile-brittle transition regime. As many researchers have shown, the failure stress (σ_f) of the material could be approximated as a constant. The characteristic length, or the critical distance (r_c) from the crack tip, at which σ_f is reached, is shown to be temperature dependent based on the crack tip stress field calculated by the finite element method. With the J-A₂ two-parameter constraint theory in fracture mechanics, the fracture toughness (J_C or K_JC) can be expressed as a function of the constraint level (A₂) and the critical distance r_c. This relationship is used to predict the fracture toughness of A533B-1 in the ductile-brittle transition regime with a constant σ_f and a set of temperature-dependent r_c. It can be shown that the prediction agrees well with the test data for wide range of constraint levels from shallow cracks (a/W = 0.075) to deep cracks (a/W = 0.5), where a is the crack length and W is the specimen width.