T-scaling method for stress distribution scaling under small-scale yielding and its application to the prediction of fracture toughness temperature dependence

Abstract

In this paper, a new method for scaling the crack-tip stress distribution under small-scale yielding conditions is proposed and named the T-scaling method. This method enables identification of the different stress distributions for materials with different tensile properties but identical load in terms of K or J. Then, by assuming that the temperature dependence of a material is represented by the stress-strain relationship temperature dependence, a method to predict the fracture load at an arbitrary temperature from the already known fracture load at a reference temperature is proposed. This method is combined with the T-scaling method and the knowledge that the “fracture stress for slip induced cleavage fracture is temperature independent.” Once the fracture load is assumed, the fracture toughness Jc at the temperature under consideration can be evaluated by running elastic-plastic finite element analysis. Finally, the above-mentioned framework for predicting the Jc temperature dependence of a material in the ductile-to-brittle temperature region was validated for 0.55% carbon steel JIS S55C and reactor pressure vessel steel A533B. The proposed framework seems to be able to solve the problem faced by the master curve in the relatively high temperature region by requiring only tensile tests.