Abstract
Petrochemical vessels exposed to high temperature and high pressure hydrogen gas may suffer from high temperature hydrogen attack (HTHA). HTHA is a hydrogen-induced degradation of carbon steels whereby internal hydrogen reacting with carbides forms methane gas bubbles, mainly on grain boundaries (GBs), with an associated loss in strength that can result in premature fracture of structural components. The design of equipment against HTHA is primarily based on the use of the empirical Nelson curves which are phenomenological and do not account for the underlying failure mechanisms and the material microstructure. Starting from the underlying deformation and fracture mechanisms, we present a simple constraint-based model for failure of steels by HTHA which involves growth of GB voids due to coupled diffusion of atoms along the GBs and creep of the matrix surrounding the voids. Since voids form only on some of the GBs, the uncavitated GBs geometrically constrain the growth of voids on the cavitated ones. The model is used to study void growth in HTHA of 21/4Cr–1Mo steel both in the presence and absence of externally applied stress. In the latter case, the model predictions are in good agreement with experimental results. Lastly, the model is used to develop a Nelson-curve type diagram in the presence of external stress in which the curves demarcating the safe/no-safe regimes are functions of the time to failure. This diagram though should be viewed as the result of the application of a new methodology toward devising mechanism-based Nelson curves and not as proposed new Nelson curves for the steel under investigation.
| Original language | English |
|---|---|
| Journal | International Journal of Fracture |
| Volume | 219 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Sep 1 2019 |
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All Science Journal Classification (ASJC) codes
- Computational Mechanics
- Modelling and Simulation
- Mechanics of Materials
Cite this
A model for high temperature hydrogen attack in carbon steels under constrained void growth. / Dadfarnia, Mohsen; Martin, May L.; Moore, David E.; Orwig, Steve E.; Sofronis, Petros Athanasios.
In: International Journal of Fracture, Vol. 219, No. 1, 01.09.2019.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A model for high temperature hydrogen attack in carbon steels under constrained void growth
AU - Dadfarnia, Mohsen
AU - Martin, May L.
AU - Moore, David E.
AU - Orwig, Steve E.
AU - Sofronis, Petros Athanasios
PY - 2019/9/1
Y1 - 2019/9/1
N2 - Petrochemical vessels exposed to high temperature and high pressure hydrogen gas may suffer from high temperature hydrogen attack (HTHA). HTHA is a hydrogen-induced degradation of carbon steels whereby internal hydrogen reacting with carbides forms methane gas bubbles, mainly on grain boundaries (GBs), with an associated loss in strength that can result in premature fracture of structural components. The design of equipment against HTHA is primarily based on the use of the empirical Nelson curves which are phenomenological and do not account for the underlying failure mechanisms and the material microstructure. Starting from the underlying deformation and fracture mechanisms, we present a simple constraint-based model for failure of steels by HTHA which involves growth of GB voids due to coupled diffusion of atoms along the GBs and creep of the matrix surrounding the voids. Since voids form only on some of the GBs, the uncavitated GBs geometrically constrain the growth of voids on the cavitated ones. The model is used to study void growth in HTHA of 21/4Cr–1Mo steel both in the presence and absence of externally applied stress. In the latter case, the model predictions are in good agreement with experimental results. Lastly, the model is used to develop a Nelson-curve type diagram in the presence of external stress in which the curves demarcating the safe/no-safe regimes are functions of the time to failure. This diagram though should be viewed as the result of the application of a new methodology toward devising mechanism-based Nelson curves and not as proposed new Nelson curves for the steel under investigation.
AB - Petrochemical vessels exposed to high temperature and high pressure hydrogen gas may suffer from high temperature hydrogen attack (HTHA). HTHA is a hydrogen-induced degradation of carbon steels whereby internal hydrogen reacting with carbides forms methane gas bubbles, mainly on grain boundaries (GBs), with an associated loss in strength that can result in premature fracture of structural components. The design of equipment against HTHA is primarily based on the use of the empirical Nelson curves which are phenomenological and do not account for the underlying failure mechanisms and the material microstructure. Starting from the underlying deformation and fracture mechanisms, we present a simple constraint-based model for failure of steels by HTHA which involves growth of GB voids due to coupled diffusion of atoms along the GBs and creep of the matrix surrounding the voids. Since voids form only on some of the GBs, the uncavitated GBs geometrically constrain the growth of voids on the cavitated ones. The model is used to study void growth in HTHA of 21/4Cr–1Mo steel both in the presence and absence of externally applied stress. In the latter case, the model predictions are in good agreement with experimental results. Lastly, the model is used to develop a Nelson-curve type diagram in the presence of external stress in which the curves demarcating the safe/no-safe regimes are functions of the time to failure. This diagram though should be viewed as the result of the application of a new methodology toward devising mechanism-based Nelson curves and not as proposed new Nelson curves for the steel under investigation.
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U2 - 10.1007/s10704-019-00376-8
DO - 10.1007/s10704-019-00376-8
M3 - Article
VL - 219
JO - International Journal of Fracture
JF - International Journal of Fracture
SN - 0376-9429
IS - 1
ER -