Size effects in the Charpy V-notch test

Abstract

Issues related to the size dependence of the upper shelf energy (USE) and the ductile-to-brittle transition temperature (DBTT) in the Charpy V-notch test are investigated. Emphasis is placed on the interplay between inertial, strain rate hardening, strain hardening, thermal softening and material length scale effects. Geometrically similar specimens are considered first. For such specimens, the ductile-to-brittle transition temperature is found to increase with specimen size, with the amount of the increase depending on the material properties. To model available experiments, calculations are also carried out for Charpy specimens where only the ligament size is varied and two classes of pipe steels are considered. For a relatively high strength pipe steel, the experimental results exhibit no size dependence of the DBTT. On the other hand, a significant shift in the DBTT is obtained for a low strength steel. The numerical studies are used to understand the difference between these two classes of steels. The extent to which the size effect is material dependent is investigated.