Informativeness of measurements of impact toughness

Measurements of the geometry of a specimen and a fracture are a useful supplement to measurements of the impact toughness and are more reliable than the determination of the “fraction of the ductile component.” Optimum (with respect to the maximum likelihood principle) estimation of the reliability of the shift of serial curves of impact toughness and critical temperatures is suggested. A Mesnager specimen may be more sensitive to the brittleness due to grain boundaries and to banded arrangement of structure than a Charpy specimen; for this reason the replacement of the norms of KCU impact toughness by KCV is not always valid.