Mixed-mode stress-corrosion cracking of high-strength steel: the role of cyclic load history

This work describes experimental evidence of mixed-mode stress-corrosion cracking of high-strength steel and discusses the role of cyclic load history. To this end, finite deformation analysis of a plane strain crack subjected to mode I loading under small scale yielding was performed and different continuum mechanics variables analysed throughout the pre-loading route, in particular the equivalent plastic strain as a measure of mechanical damage. Results of the computational elastoplastic analysis of stress-strain evolution in the vicinity of the crack tip subjected to fatigue and subsequent rising loading are consistent with the experimental fact of anisotropic cracking behaviour of prestressing steel in corrosive environment. It can explain (if coupled with the inherent anisotropy associated with the oriented microstructure of the steel) why crack branching takes place at a deflection angle in relation to mode I crack extension.