Influence of Hydrogen on Crack Growth Resistance of Steels for Energy Infrastructure Applications

The aim of this study was to develop a methodology to investigate hydrogen effects on crack growth resistance in low alloy ferritic steels using cathodic hydrogen precharging with the focus on stable crack growth in pressure vessel steel grade P355NH. Inert gas fusion measurements (IGF) were performed to determine hydrogen uptake and estimate diffusion behavior. Numerical calculations allowed a first prediction of the concentration profile in compact tension specimens. To assess the influence of internal hydrogen on crack growth resistance, fatigue precracking was performed and J-Δa-curves were measured. Accelerated fatigue crack growth was observed for high stress intensities and low frequencies. In the J-Δa-analysis, the crack growth resistance in hydrogen charged material was reduced in contrast to uncharged specimens. However, no unstable crack growth was perceivable. In conclusion, the steel remains predominately ductile with the applied charging conditions.