A probabilistic model to predict specimen geometry effects on fracture toughness in ferritic–pearlitic steels

This work describes a probabilistic framework for cleavage fracture of ferritic–pearlitic steels incorporating experimental measurements of microcrack distribution associated with the cracking of the pearlitic microstructure. A central objective of this study is to explore and further extend application of a probabilistic framework incorporating the statistics of microcracks to predict specimen geometry effects on the fracture toughness distribution for a typical ferritic–pearlitic structural steel. Fracture toughness values for an ASTM A572 Grade 50 structural steel derived from fracture tests using conventional SE(B) specimens with varying thickness and $a/W$-ratios provide the cleavage fracture resistance data needed to assess specimen geometry effects on the probability distribution of $J_c$-values. The present exploratory study successfully predicts the measured statistical distribution of cleavage fracture toughness in shallow crack specimens and provides further support of the proposed probabilistic model as a more advanced and effective engineering-level procedure in fracture assessment methodologies.