THE EFFECT OF IRRADIATION-INDUCED MATRIX BARRIER HARDENING ON IRRADIATION-ASSISTED STRESS CORROSION CRACKING (IASCC) IN AUSTENITIC STEELS AND NICKEL BASED ALLOYS

摘要

Mechanistic models for inter-granular (IG) fracture are reviewed. The favoured approach considers a propagating IG crack with plastic deformation occurring at the crack tip. The key parameter in controlling the ease of crack propagation is the work offracture, which is linked to the fracture toughness. It will be shown that the work of fracture can be estimated through a series of equations that consider: 1) surface energy; 2) work hardening exponent; 3) grain boundary (GB) energy; 4) GB segregation of embrittling elements; and 5) GB structure. In particular, the effects of barrier hardening on the GB energy (item 3)) will be reviewed. New equations describing the influence of irradiation-induced: 1) dislocation loop damage; 2) precipitation; on the GB energy, will be discussed. The relation of fracture toughness predicted by the model to IASCC growth rates and initiation times will be assessed. Applications of the new model to IASCC in austenitic steels and nickel based alloys will be described.