PREDICTION ON INITIATION OF HYDROGEN-INDUCED DELAYED CRACKING IN HIGH-STRENGTH STEEL BASED ON COHESIVE ZONE MODELING

This study presents prediction on initiation of hydrogen induced delayed cracking (HIDC) in hydrogen pre-charged high-strength steel notched bars under a constant load based on hydrogen influenced cohesive zone modeling (CZM). The prediction is implemented by using a three-step sequential coupling finite element procedure including elastic-plastic stress analysis, stress-assisted hydrogen diffusion analysis and cohesive stress analysis with cohesive elements embedded along the potential crack path. Hydrogen influenced linear traction separation law is applied to the cohesive elements. The predicted initiation time of HIDC gives a good agreement with the experimental fracture time reported in a literature. The prediction reproduces the experimental trend that the critical hydrogen concentration for crack initiation is independent of the initial hydrogen concentration, while decreases with increasing load or stress concentration factor of the notch. CZM has a potential to predict HIDC of high-strength steel.