Calibration of Weibull parameters using the conventional mechanism-based strain gradient plasticity

This paper recalibrates the Weibull modulus and the threshold fracture toughness in a three-parameter Weibull stress model for the cleavage assessment of the pressure vessel steel reported in a European Union Project. The description of the near-tip stress field, which contributes to the primary force driving the unstable cleavage fracture, utilizes the conventional, mechanism-based strain gradient plasticity theory. The thus calibrated Weibull modulus and threshold toughness do not exhibit significant dependence on the material length scale. The calibrated Weibull stress model based on this plasticity theory predicts an increased probability of fracture compared to that based on the classical plasticity.