Towards a micro-mechanical description of the fracture behaviour for RAFM steels in the ductile-to-brittle transition regime

A combined experimental and continuum mechanics approach is used to interpret cleavage fracture results of the F82Hmod reduced activation steel. Cleavage fracture parameters are obtained by numerical evaluation of tensile tests using axisymmetrically notched and pre-cracked specimens and subsequent statistical analysis. Prediction of fracture origin distribution was performed using the cleavage fracture results and fractographic examinations were used to compare prediction and experimental results. The local risk of rupture is defined and utilized as quantity for transferability assessment between different specimen geometries. The role of large strains preceding cleavage fracture is addressed. While results are very satisfactory for small fracture strains, the presence of large strains and transferability to pre-cracked specimens poses some difficulties. A possible explanation for this is given.