Mitigating high temperature hydrogen attack with interphase precipitation

• Published in: International journal of hydrogen energy 2024-01, Vol.50, p.189-198
• Main Authors: Alshahrani, M.A.M., Ooi, S.W., Divitini, G., Bhadeshia, H.K.D.H.
• Format: Article
• Language: English
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2023.09.179

The attack on steel by reaction with high-pressure hydrogen at elevated temperatures can jeopardise structural integrity in oil & gas industries. Following dissociation, the hydrogen penetrates the steel to react with the carbon present in the ferrite to form methane bubbles within the microstructure. This depletion of carbon in the ferrite causes the dissolution of carbides in order to maintain the ferrite-carbide equilibrium. Therefore, thermodynamically more stable carbides which cause a reduced activity of carbon improve the stability of the steel to hydrogen attack. In this work, we investigate specifically the response of the interphase precipitation of alloy carbides that form during the transformation from γ to α, on hydrogen attack. It is demonstrated quantitatively that the vanadium carbides thus produced enhance the resistance to attack when compared with data from an earlier study involving current, commercially-used steel in the petrochemical industries. •Isothermally heat-treated vanadium steel was shown to mitigate hydrogen attack.•Vanadium carbides reduced carbon activity, hence resisted depletion by hydrogen.•Undesirable martensite formation led to high carbon activity and methane formation.•Heat treatment is a must-include parameter in standards to reduce carbon activity.