Chemical potential and surface energy in stress–corrosion cracking

Abstract

The energy-balance approach has been further utilized to demonstrate that toughness is sensitive to surface energy, even when extensive plasticity develops during fracture. It is assumed that the plastic work done is directly proportional to the effective surface energy and this is justified with reference to a ‘microbrittle’ model. The reduction in critical stress intensity is therefore directly attributable to changes in free energy caused by the embrittling environment. Published data have been used to illustrate the model for hydrogen embrittlement and for yield-assisted anodic dissolution mechanisms. These indicate that errors due to micro plastic tearing and to non-singular tractions in the crack plane can be largely disregarded.