Journal ArticleDOI
A statistical, physical-based, micro-mechanical model of hydrogen-induced intergranular fracture in steel
TLDR
In this paper, the authors present a comprehensive physical-based statistical micro-mechanical model of hydrogen embrittlement which they use to quantitatively predict the degradation in fracture strength of a high-strength steel with increasing hydrogen concentration, with the predictions verified by experiment.Abstract:
Intergranular cracking associated with hydrogen embrittlement represents a particularly severe degradation mechanism in metallic structures which can lead to sudden and unexpected catastrophic fractures. As a basis for a strategy for the prognosis of such failures, here we present a comprehensive physical-based statistical micro-mechanical model of such embrittlement which we use to quantitatively predict the degradation in fracture strength of a high-strength steel with increasing hydrogen concentration, with the predictions verified by experiment. The mechanistic role of dissolved hydrogen is identified by the transition to a locally stress-controlled fracture, which is modeled as being initiated by a dislocation pile-up against a grain-boundary carbide which in turn leads to interface decohesion and intergranular fracture. Akin to cleavage fracture in steel, the “strength” of these carbides is modeled using weakest-link statistics. We associate the dominant role of hydrogen with trapping at dislocations; this trapped hydrogen reduces the stress that impedes dislocation motion and also lowers the reversible work of decohesion at the tip of dislocation pile-up at the carbide/matrix interface. Mechanistically, the model advocates the synergistic action of both the hydrogen-enhanced local plasticity and decohesion mechanisms in dictating failure.read more
Citations
More filters
Journal ArticleDOI
Hydrogen Embrittlement Understood
Ian M. Robertson,Ian M. Robertson,Petros Athanasios Sofronis,Petros Athanasios Sofronis,Akihide Nagao,May L. Martin,Shuai Wang,Shuai Wang,D. W. Gross,Kelly E. Nygren +9 more
TL;DR: The connection between hydrogen-enhanced plasticity and the hydrogen-induced fracture mechanism and pathway is established through examination of the evolved microstructural state immediately beneath fracture surfaces including voids, quasi-cleavage, and intergranular surfaces as discussed by the authors.
Journal ArticleDOI
Hydrogen Embrittlement Understood
Ian M. Robertson,Ian M. Robertson,Petros Athanasios Sofronis,Petros Athanasios Sofronis,Akihide Nagao,May L. Martin,Shuai Wang,Shuai Wang,D. W. Gross,Kelly E. Nygren +9 more
TL;DR: The connection between hydrogen-enhanced plasticity and the hydrogen-induced fracture mechanism and pathway is established through examination of the evolved microstructural state immediately beneath fracture surfaces including voids, quasi-cleavage, and intergranular surfaces as discussed by the authors.
Journal ArticleDOI
The synergistic action and interplay of hydrogen embrittlement mechanisms in steels and iron: Localized plasticity and decohesion
TL;DR: In this paper, a review of the synergistic interplay of hydrogen embrittlement mechanisms in STEEL and IR is presented, with a particular emphasis on the proposal of the novel and unified HELP+HEDE model based on the specific microstructural mapping of the dominant HE mechanisms with implications on the fracture process and resulting hydrogen-assisted fracture modes.
Journal ArticleDOI
Dislocation interactions with grain boundaries
TL;DR: In this article, a review of recent progress in understanding dislocation interactions with grain boundaries and interfaces in metallic systems via static and in situ dynamic experimental approaches is reviewed, as well as a comparison of different experimental approaches.
Journal ArticleDOI
On the formation and nature of quasi-cleavage fracture surfaces in hydrogen embrittled steels
TL;DR: In this paper, a combination of topographical reconstruction of secondary electron microscope fractographs and a transmission electron microscopy study of the microstructure from site-specific locations is shown that the features on quasi-cleavage surfaces are ridges that can be correlated with sub-surface intense and highly localized deformation bands.
References
More filters
Book
Theory of Dislocations
John Price Hirth,Jens Lothe +1 more
TL;DR: Dislocations in Isotropic Continua: Effects of Crystal Structure on Dislocations and Dislocation-Point-Defect Interactions at Finite temperatures.
Journal ArticleDOI
Effects of hydrogen on the properties of iron and steel
TL;DR: In this paper, the effects of hydrogen on the physical and mechanical properties of iron and steel are reviewed and a new mechanism for the cold work peak for hydrogen in iron is considered.
Journal ArticleDOI
Hydrogen-enhanced localized plasticity—a mechanism for hydrogen-related fracture
TL;DR: In this article, a theory of hydrogen shielding of the interaction of dislocations with elastic stress centres is outlined, which can account for the observed hydrogen-enhanced dislocation mobility.
Journal ArticleDOI
On the relationship between critical tensile stress and fracture toughness in mild steel
TL;DR: In this paper, the critical value of tensile stress (a) for unstable cleavage fracture to the fracture toughness (K,,) for a high-nitrogen mild steel under plane strain conditions.
Journal ArticleDOI
The diffusion and trapping of hydrogen in steel
TL;DR: In this paper, the mobility of dissolved hydrogen in an iron lattice having a population of extraordinary, or trapping, sites for hydrogen is analyzed under the assumption of local equilibrium between the mobile and the trapped populations.