The meaning of the thresholds of hydrogen-assisted cracking

Abstract

We analyze the concept of threshold stress intensity factor K~AC and its importance for the processes of hydrogen-assisted cracking (HAC). We discuss the self-similarity of the zone near the crack tip welldescribed by the stress intensity factors K, indicate the ambiguities encountered in the determination of KHAC and the experimental parameters affecting the thresholds of hydrogen-assisted cracking parallel with K. It is shown that KnA c has the physical meaning of the lower bound of the stress-intensity factors corresponding to the initiation of hydrogen-assisted cracking (if all other conditions are arbitrary). To obtain reliable estimates of KnAc, one must impose additional restrictions on the experimental procedure of its evaluation.

Failure analysis of pre‐stressed high strength steel bars used in a wind turbine foundation: Experimental and FE simulation

“…Low alloy high strength steels are often used as bars or cables in the structures to withstand the prestress. However, in recent years, failure events due to sudden fracture of the high strength steel bars or cables have been frequently reported, and the fracture has been related to hydrogen-assisted cracking (HAC) [1][2][3][4][5][6][7], which is a well-known phenomenon often giving rise to the fracture of many high strength structures containing internal hydrogen or being exposed to hydrogen-containing environments [1][2][3][4][5][6][7].…”