Subcritical Crack Growth

Subcritical Crack Growth

Subcritical crack growth (SCG) refers to the slow growth of a Subcritical flaw as a result of its exposure to the combined effect of stress and a corrosive environment. The combination of a reactive atmosphere and a stress concentration can greatly enhance the rate of crack propagation. For instance, silica will dissolve in water at a rate of 10^-17m/s, whereas the application of stress can cause cracks to grow at speeds greater than 10^-3 m/s. The insidiousness of, and hence the importance of understanding, this phenomenon lies in the fact that as the crack tip advances, the material is effectively weakened and eventually can give way suddenly and catastrophically after years of service.