Significance of limiting (equivalent) tip radius and crack tip deformation for cleavage induced fracture in structural steels

Abstract

In two structural steels, the limiting crack tip radius (LTR) and the crack tip blunting radius have been evaluated at the instant of fracture initiation by cleavage. The effect of yield strength on LTR and the blunting radius has been investigated. The relationship between the limiting and the blunting tip radius has been studied. The limiting tip radius has been found to be of the order of the plastic zone radius in the structural steels investigated.

Ductile vs. brittle behavior of pre-cracked nanocrystalline and ultrafine-grained materials

“…The influence of the blunting radius, characterizing crack tip curvature, on fracture toughness has been investigated in Refs. [23][24][25][26][27]. It appears that fracture toughness decreases with a decrease in the crack tip radius, at least until the crack tip radius becomes smaller than some critical value at which fracture toughness reaches a constant limiting value.…”