A theoretical model for determination of fracture toughness of reactor pressure vessel steels in the transition region from automated ball indentation test

A theoretical model is proposed to estimate the fracture toughness of ferritic steels in the transition region from ball indentation test data, The key concept of the model is that the indentation energy to a critical load is related to the fracture energy of the material. By applying the new model, the fracture parameters of reactor pressure vessel steel base and weld metals were estimated from the indentation load-depth curves. The estimated fracture stresses agreed well with those of the Wilshaw et al. model. The temperature dependence of the estimated K-JC was almost the same as that of the ASTM K-JC master curve. Also, the reference temperature obtained from the estimated K-JC versus temperature curve correlated well with the index temperature of 41 J Charpy impact energy, T-41J. Additionally, the ball indentation deformation was simulated by ABAQUS code to evaluate the stress state and the result was compared with that at the crack tip. (C) 1998 Elsevier Science B.V.