Hydrogen-assisted cracking (HAC) of high-strength steels as a function of the hydrogen pre-charging time

Abstract

This work demonstrates that by performing hydrogen-assisted cracking (HAC) as a function of hydrogen pre-charging time, highly symmetric circumferential cracks can be generated in circumferentially notched or grooved round bars made of high-strength steels, which can be used to study HAC in terms of fracture mechanics. Using the simple-to-perform method, control over hydrogen-assisted crack initiation is achieved by applying low hydrogen pre-charging times and by determining a threshold minimum preload to failure LHAC. The uniaxial tensile testing at LHAC under constant displacement results in a characteristic load-time-curve as well as a high-symmetry circumferential crack for each material investigated in this study. Finally, the minimum preload to failure, the time to failure and the critical crack length are each exhibited as a function of hydrogen pre-charging time and an approach to the application of fracture mechanics with the aim of determining the threshold stress intensity KIHAC is discussed.