Characterization of transition temperature behavior of HY130 steel by the [formula omitted] fracture toughness parameter

Abstract

The objectives of this study were to determine whether the J-R curve approach could be used to evaluate the ductile to brittle temperature performance of a high yield strength structural steel (HY130) and to demonstrate that the single specimen unloading compliance method is applicable to evaluate J Ic values and J-R curves for compact specimens tested at temperatures from −192 to 150°C. The major conclusions of this work are that J Ic and the complete J-R curve can be obtained using the single specimen method over the above temperature range and that J Ic does define a ductile to brittle transistion temperature for HY130 steel which should be more valuable for structural design than that found from Charpy V or dynamic tear specimens because it is based on a fracture toughness parameter. The comparison of the Ic transition temperature and that from Charpy V specimens shows that the Charpy V transition temperture is more conservative for the HY130 steel tested. In transitional J I specimens which demonstrated a ductile crack tearing followed by a brittle failure, scanning microscope stereo pair fractography showed that the transition from ductile to brittle behavior was very gradual in comparison to the distinct crack tips obtained on ductile specimens broken in a brittle fashion at a cryogenic temperature.