Constant displacement loading under gaseous charging at elevated pressure over a long time is a convenient method for determining the resistance of materials against hydrogen-induced cracking (HIC). This work investigates the feasibility of using compact tension (CT) specimens loaded by double-tapered wedges, as the combination of CT specimens and wedge loading benefits not only from small specimens that can be easily manufactured, but also from a straightforward loading method. As recalculating the applied stress intensity factor (SIF) after HIC testing is challenging for a wedge-loaded CT specimen, an experimental-numerical method is proposed for determining the SIF. Firstly, the separation load between the wedge and the specimen was experimentally obtained from a lift-off curve and, secondly, a correction factor calculated using finite element analysis (FEA) was applied to predict the equivalent contact load between the wedge and the specimen. To verify the proposed approach, the threshold SIF (\: K₈₇) of high-strength steel (HSS) DIN 55NiCrMoV7 in gaseous hydrogen was determined using wedge-loaded CT specimens as well as standard bolt-loaded compact specimens. The comparison of \: K₈₇ obtained with both types of specimens revealed a good agreement, which confirmed the feasibility of the proposed method.
Jabbari et al. (Thu,) studied this question.
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