Brittle Fracture Initiation of Steel at the Temperature of the Ductile-to-Brittle Transition Region : 2nd Report, Estimation of the Fracture Toughness

Abstract

In the previous paper, it was shown that the strain energy release rate at brittle fracture initiation could be employed as the criterion for the ductile-to-brittle transition in the Charpy test. In this paper, the relation between the strain energy release rate at the temperature of the ductile-to-brittle transition region and the fracture toughness at low temperature is discussed. For the purpose the Charpy impact test for specimens with pre-fatigue crack and the three point bending fracture toughness test were carried out. Consequently, it was shown that the strain energy release rate corresponded to the fracture toughness obtained from the three point bending test in accordance with the ASTM E 399-72 standard.