A probabilistic model for prediction of cleavage fracture in the ductile-to-brittle transition region and the effect of temperature on model parameters

This paper presents a modified Weibull stress model which accounts for the effects of plastic strain and stress triaxiality at the crack tip region. The proposed model is applied to predict cleavage fracture in a modified A508 pressure vessel steel. It is demonstrated that the Weibull modulus (m  ) remains a constant in the temperature range considered. The threshold value for the Weibull stress model, σw−minσw−min, decreases with temperature due to decrease of the yield stress with temperature. The Weibull stress scale parameter, σu, increases with temperature reflecting the combined effects of temperature on material flow properties and toughness. The proposed Weibull stress model accurately predicts the scatter of the measured fracture toughness data and the strong effects of constraint and temperature on cleavage fracture toughness.