A methodology for the numerical assessment of autofrettage influence on hydrogen content near a notch in a 4130 steel pressure vessel

摘要

Highlights?A vessel storing hydrogen at 70MPa is simulated in a Finite Element model.?Hydrogen concentrations are calculated in the vicinity of the notch.?The optimum autofrettage pressure is found by means of response surfaces.?Notch size influence is also analysed.AbstractThe introduction of compressive residual stresses, e.g. by means of an autofrettage process, is a common strategy in industry for the improvement in fatigue life of high-pressure vessels. The application of autofrettage process in a vessel, storing hydrogen at 70MPa, is evaluated here. Compressive stresses make difficult the entry of hydrogen in the metal lattice, however the produced plastic strain might be related to the creation of trapping sites for hydrogen. The balance between these two phenomena is analysed. In addition, the likely presence of notches is considered since stress concentrators increase the level of hydrostatic stress and p