Investigation of Residual Stress Effect on Cleavage Fracture Toughness in the Transition Temperature Region by Considering the Crack-Tip Constraint

An advanced standard method for predicting fracture in the ductile-to-brittle transition region is the fracture toughness master curve. When the master curve is applied to a structure with a low-constraint geometry, utilizing the standard fracture toughness method may result in an overly conservative estimation of structural performance. In this study, the effect of residual stresses on the fracture toughness of ferritic steels was investigated in the transition region, and the applicability of the fracture toughness master curve to evaluate the integrity of structures with different geometries was enhanced. In this study, specimens made of ferritic steel with varying crack-tip constraints but the same level of residual stresses were examined. This study determined the fracture toughness in the transition regime for these specimens. Level of crack-tip constraint for specimens with residual stress was determined using a novel method. A comparison of the results of the reference temperature of the non-residual stress specimens with the results of the experimental tests shows that the presence of tensile residual stresses in the specimens with different crack-tip constraint levels leads to an increase in the reference temperature by at least 24 °C for specimens with high crack-tip constraint.