Review and perspective on approaches of evaluating cleavage fracture toughness of pressure vessel steels

Although efforts have been made to establish cleavage fracture model in the past 30 years or so, uncertainties remain in predicting the cleavage fracture toughness behavior of reactor pressure vessel steels in the transition region. Confusions may be raised in cases such as that there are still outliers while ASME fracture toughness curve indexed to the reference temperature is generally considered as very conservative. The advantage and potentials of using Finite Element method to predict the cleavage fracture behavior of irradiated materials are obvious. However, its effectiveness depends on the rightness of the physical model and criteria established. In this paper, approaches of describing cleavage fracture toughness of pressure vessel steels in the transition region are discussed and compared. The need for focusing on the physical fundamental and criteria of cleavage fracture is addressed. (authors)