ABSTRACT
In this chapter, the authors deal with Environment-Assisted Cracking (EAC) that occurs under sustained and cyclic loading at temperatures below the levels at which creep becomes a significant consideration. In the 1960s exploratory experiments were performed to document the effects of environment on subcritical crack growth in high strength materials. The crack initiated on the internal surface of the tube by a mechanism called delayed hydride cracking. Hydride cracking has been simulated in Zirconium alloys in the laboratory and has been observed in other hydride forming metals. Atomic hydrogen diffuses into the crack tip region and degrades the strength of atomic bonds. The chapter discusses the fracture mechanics approach for measuring and correlating the kinetics of crack growth during EAC, regardless of the underlying mechanism.
