Benchmark on the determination of the cleavage triggering sites in a RPV steel in the DBT range

This paper presents the work undertaken as a benchmark on fracture micromechanisms. A systematic investigation of the nature and position of cleavage initiating sites has been carried out on selected specimens of an ASTM A508 C1.3 steel by seven laboratories. Observations were carried out on three different kinds of specimens, i.e. Charpy V-Notch, Compact Tension and Notched Tensile specimens, at different testing temperatures in the ductile-to-brittle (DBT) range. Participants were asked to follow a proposed methodology to determine both the main cleavage triggering site and its location with respect to the given reference frame. A correct agreement was found between participants for the determination of the cleavage initiating site as far as CVN and CT specimens were concerned. For NT specimens, the presence of a ductile damage zone with debonded inclusions only enabled participants to agree on the mesoscopic scale.