Fracture at V-notches with contained plasticity

Fracture at V-notches with contained plasticity was studied. The tested material was a soft annealed tool steel, AISI O1, at −50°C. The material behaviour at this temperature was brittle for a standard fracture toughness test and ductile for a tensile test. Single-edge notched tension and three-point bend specimens were tested, with notch angles ranging from 0° to 140°. For the same notch angle, both brittle and ductile fracture occurred depending on the geometry. However, transferability between different geometries prevailed if the fracture was brittle. re loci derived from simple point-stress or mean-stress criteria were fitted to the experimental results. The trend of the experimental results was followed well even though the fracture loci were derived under the assumption of linear elastic stresses. However, a fracture criterion based on the fracture toughness and a tension test alone will provide a conservative fracture locus. fect of introducing a notch radius on the used fracture criteria is discussed within the context of linear elastic analysis. As expected, a mean-stress criterion is more sensitive to changes in the notch radius than a point-stress criterion. For both criteria, the sensitivity for changes in the notch radius is less for larger notch angles.