Hydrogen embrittlement mechanisms in advanced high strength steel
Gong, Peng and Turk, Andrej and Nutter, John and Yu, Feng and Wynne, Bradley and Rivera-Diaz-del-Castillo, Pedro and Rainforth, W. Mark (2021) Hydrogen embrittlement mechanisms in advanced high strength steel. Acta Materialia, 223. 117488. ISSN 1359-6454 (https://doi.org/10.1016/j.actamat.2021.117488)
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Abstract
Hydrogen embrittlement is increasingly important in advanced high strength steels (AHHS) as strength levels increase well above 1000MPa. This work developed a detailed understanding of the embrittling mechanism in model AHHS steels based on Fe-Ti-Mo and Fe-V-Mo, both strengthened through interphase precipitation. Hydrogen charging led to an increase in the dislocation density and an enlarged strain field around precipitates, resulting in an increase in residual stress. This was much greater for the Ti-Mo steel compared to the V-Mo. Important differences in the hydrogen trapping behaviour was seen between the two steels, with hydrogen believed to be trapped at the matrix/precipitate interface for the Ti-Mo steel, but within the precipitate for the V-Mo steel. The effects of hydrogen were investigated in detail for slow strain rate tensile tests and double notched tensile samples. Hydrogen charging resulted in a loss in strength and ductility, with the Ti-Mo steel failing at yield, while the V-Mo steel exhibited a ∼13% loss in strength and a ∼ 35% loss of ductility. Crack initiation in tensile samples occurred at high strain gradient dislocation boundaries. However, crack propagation rapidly became quasi-cleavage, along the {100} plane in ferrite, and also along the martensite/ferrite grain boundaries on the {110} plane in the martensite. Minimal plasticity was observed associated with the crack tip, which was believed to be a result of the suppression of dislocation emission at the crack tip by the hydrogen.
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Item type: Article ID code: 78687 Dates: DateEvent16 November 2021Published16 November 2021Published Online13 November 2021AcceptedSubjects: Technology > Mechanical engineering and machinery Department: Faculty of Engineering > Mechanical and Aerospace Engineering Depositing user: Pure Administrator Date deposited: 24 Nov 2021 16:28 Last modified: 28 Nov 2024 03:48 URI: https://strathprints.strath.ac.uk/id/eprint/78687