Defect tolerance under environmentally assisted cracking conditions

Notch sensitivity effects under environmentally assisted cracking (EAC) conditions have been recently quantified considering the tolerance to short cracks that may start at their tips and become nonpropagating after growing for a while, a behavior that depends on the stress gradients ahead of the notch tips and on the basic material resistances to crack initiation and propagation inside an aggressive medium. This model can provide a powerful alternative design tool for the pass/nonpass criterion traditionally used to deal with such mechanical-chemical problems, since it properly considers and quantifies the stress analysis issues that affect them. The model uses the analogy between the notch sensitivity behavior under fatigue and under EAC conditions, so it quantifies how the stress gradient around the notch tips affects the tolerance to mechanically short cracks that depart from there, considering the characteristics of the loading and of the notch geometry, as well as the basic material properties inside the given environment, expressed by its EAC resistances to crack initiation from a smooth surface S-EAC and to crack propagation K-IEAC, without the need for any data fitting parameter. Moreover, since this model has been validated by proper tests, it can be used to propose a defect-tolerant design criterion under EAC conditions that includes the unavoidable notch effects always present in actual structural components.