Plastic zone evolution near a crack tip and its role in environmentally assisted cracking

摘要

This paper analyzes the effects of crack tip plastic strains and compressive residual stresses, createdby fatigue pre-cracking, on environmentally assisted cracking of pearlitic steel subjected to localized anodicdissolution and hydrogen assisted fracture. In both situations, cyclic crack tip plasticity improves the behavior ofthe steel. In the respective cases, the effects are supposed to be due to accelerated local anodic dissolution ofthe cyclic plastic zone (producing chemical crack blunting) or to the delay of hydrogen entry into the metalcaused by residual compressive stresses, thus increasing the fracture load in aggressive environment.