A dislocation model for crack tip blunting in slightly predeformed low alloy steels

Previous experimental results have shown that there is a marked increase in fracture toughness in a slightly predeformed low alloy steel, namely AISI 4340 steel. This increase in toughness was attributed to an excessive blunting at the crack tip due to the presence of a high mobile dislocation density. A dislocation model is proposed to explain the crack tip blunting in predeformed low alloy steels which leads to an equation relating the …