Hydrogen-induced Crack Growth Research Articles

Guided analysis of fracture toughness and hydrogen-induced embrittlement crack growth rate in quenched-and-tempered steels using machine learning

This study focuses on developing a machine learning (ML) model, specifically a Bayesian-optimized deep neural network, leveraging numerical simulation data for the prediction of fracture toughness (KIC) and crack growth rate (CGR) in Quenched-and-Tempered Steel (AISI 4140 alloy) under hydrogen embrittlement conditions. The proposed model demonstrated superior accuracy with Root Mean Squared Error (RMSE) values of 0.052 for KIC and 0.084 for CGR, surpassing conventional ML models including random forest (0.094 for KIC, 0.139 for CGR), gradient boosting (0.184 for KIC, 0.196 for CGR), support vector regression (0.142 for KIC, 0.110 for CGR), and decision tree regression (0.119 for KIC, 0.133 for CGR). The findings also revealed that input parameters such as temperature, hydrogen concentration, and hydrostatic stress carry higher weight factors compared to other parameters in predicting KIC. Similarly, the prediction of high CGR values, ranging from 5.9 × 10−5 to 9.5 × 10−5 m/s, was associated with the importance of hydrostatic stress, strain rate, and initial crack length in the prediction model. This underscores the model's ability to capture the intricate dependencies of output objectives on input features. Furthermore, a comprehensive case study, informed by the ML model, highlights the potential for tuning specific processing input parameters to manage hydrogen embrittlement effectively, contributing to a deeper understanding of its dynamics.

A coupled diffusional-mechanical model accounting for hydrogen enhancements of strain-induced dislocations and vacancies

Informed by the current understanding of hydrogen-dislocations/vacancies interactions, a coupled diffusional-mechanical model accounting for hydrogen-enhanced strain-induced dislocations and vacancies is developed. This model is applied to capture hydrogen diffusion and trapping in the uniaxially tensioned column and type-I loaded crack specimens of nickel alloy, with special attentions paid to the influence of hydrogen-vacancies interaction on them, which is seldom discussed in previous studies. The results show that the hydrogen-enhanced hardening rate and the hydrogen-promoted vacancy enrichment for the nickel alloys observed in experiments can be addressed well by the present model. The strain-induced vacancies rather than dislocations dominate the hydrogen trapping behavior, due to their higher hydrogen binding energies for the nickel alloy. The hydrogen-saturated state of vacancies can heavily impact hydrogen diffusion/trapping, which could be characterized by the effective trap concentration. The supersaturated vacancies caused by hydrogen-enhanced strain-induced vacancies can promote void growth through vacancy condensation, thus accelerating plastic localization or interface rupture. For the type-I loaded blunt crack specimen, the hydrogen-enhanced dislocation multiplication contributes to intergranular cracking in the pressure valley, while hydrogen-enhanced vacancy generation facilitates void growth in the plastic zone, both of which can exacerbate plastic localization ahead of crack tip. A quantitative model for plasticity localization that accounts for the influences of hydrogen-induced IG cracking and void growth would be helpful in physically based modeling of hydrogen embrittlement.

A review of hydrogen embrittlement in gas transmission pipeline steels

Abstract Hydrogen transport by blending hydrogen into natural gas transmission pipelines and by pure-hydrogen pipelines is a prospective mode of energy transmission during the transition to renewables. The risk of hydrogen embrittlement (HE) in pipeline steels must first be quantified to ensure safe pipeline operation. This review provides an overview of HE in pipeline steels. Most pipeline steels have reduced ductility when exposed to hydrogen partial pressures of 100 bar and above. Higher-strength pipeline steels (X80 and X100) have been found to undergo HE at ∼50 bar hydrogen. Hydrogen-induced subcritical crack growth in pipeline steels has not been reported in the literature. There are few articles on HE in pipeline welds, with some indications that the weld is more susceptible to HE, and some indications that it is less. The relationship between hydrogen pressure and absorbed hydrogen concentration has not been evaluated. Gaps in knowledge are identified in the conclusions.

Effects of inclusions on the fatigue life of SNCM439 steel in high-pressure hydrogen gas

Four heats of commercially available JIS SNCM439 steel are prepared, and fatigue tests are conducted in air and hydrogen gas. The materials evaluated are all martensitic steel with a tensile strength of 900 MPa or less and contain nonmetallic inclusions of different sizes. A decrease in the fatigue limit is observed in the specimens with large nonmetallic inclusions, but the fatigue limit in air is approximately equal to the fatigue strength at 300,000 cycles in hydrogen. However, in the finite life region, the fatigue life in hydrogen significantly decreases owing to the presence of large nonmetallic inclusions. It was observed that hydrogen considerably affects the fatigue life even at low stress amplitudes close to the fatigue limit. This effect is considered to be dependent on the size of the initial crack originating from the nonmetallic inclusions; large nonmetallic inclusions accelerate the hydrogen-induced fatigue crack growth rate.

Towards the prediction of hydrogen–induced crack growth in high–graded strength steels

This work addresses a hydrogen–induced cracking methodology incorporating the fully coupled problems of elastoplastic deformation and hydrogen transport within cohesive–interface elements framework to predict ductile tearing in high strength steels. In the present work, on one hand, the flow stress declines with escalating hydrogen concentration and, as a result, taking into account the hydrogen impact on enhancing plastic deformation in the lattice through the hydrogen enhanced localized plasticity (HELP) model. On the other hand, to implement hydrogen impact into the cohesive–interface elements in the hydrogen enhanced decohesion (HEDE) manner, a phenomenological decohesion model is adopted, leading to combining the both mechanisms (HELP + HEDE). Furthermore, a nonlinear traction–separation relationship based on the Park–Paulino–Roesler (PPR) model determines the constitutive response of the zero thickness cohesive–interface elements while the finite–strain, incremental plasticity model is accounted for the bulk material. The hydrogen–degraded PPR model provides a flexibility and control over various softening behaviours, from a convex brittle to a concave ductile shape. This computational framework is established to simulate ductile crack extension in a C(T) specimen made of AISI 4130 high strength steels. Afterwards, the parameters involved in the hydrogen–degraded PPR model are properly calibrated with experimental data for the uncharged and hydrogen–charged C(T) specimens. The key contributions of this study are to shed light on the hydrogen concentration (lattice and trapped) effects on the crack growth resistance curves and stress triaxiality. Based on the results obtained for AISI 4130 high strength steels, it has been concluded that the lattice hydrogen has the dominating factor in the hydrogen degradation compared with trapped hydrogen.

The dependence of fatigue crack growth on hydrogen in warm-rolled 316 austenitic stainless steel

The fatigue crack growth rate of warm-rolled AISI 316 austenitic stainless steel was investigated by controlling rolling strain and temperature in argon and hydrogen gas atmospheres. The fatigue crack growth rates of warm-rolled 316 specimens tested in hydrogen decreased with increasing rolling temperature, especially 400 °C. By controlling the deformation temperature and strain, the influences of microstructure (including dislocation structure, deformation twins and α′ martensite) and its evolution on hydrogen-induced degradation of mechanical properties were separately discussed. Deformation twins deceased and dislocations became more uniform with the increase in rolling temperature, inhibiting the formation of dynamic α′ martensite during the crack propagation. In the cold-rolled 316 specimens, deformation twins accelerated hydrogen-induced crack growth due to the α′ martensitic transformation at the crack tip. In the warm-rolled specimens, the formation of α′ martensite around the crack tip was completely inhibited, which greatly reduced the fatigue crack growth rate in hydrogen atmosphere.

A New Model For Hydrogen-Induced Crack (HIC) Growth in Metal Alloy Pipelines Under Extreme Pressure

Pipeline failure caused by Hydrogen-Induced Cracking (HIC), also known as Hydrogen Embrittlement (HE), is a pressing issue for the oil and natural gas industry. Bursts in pipelines are devastating and extremely costly. The explosive force of a bursting pipe can inflict fatal injuries to workers, while the combined loss of product and effort to repair are highly costly to producers. Further, pipeline failures due to HIC have a long lasting impact on the surrounding environment. Safe use and operation of such pipelines depend on a good understanding of the underlying forces that cause HIC. Specifically, a reliable way to predict the growth rate of hydrogen-induced cracks is needed to establish a safe duration of service for each length of pipeline. Pipes that have exceeded or are near the end of their service life can then be retired before the risk of HIC-related failures becomes too high. However, little is known about the mechanisms that drive HIC. To date, no model has been put forth that accurately predicts the growth rate of fractures due to HIC under extreme pressures, such as in the context of natural gas and petroleum pipelines. Herein, a mathematical model for the growth of fractures by HIC under extreme pressures is presented. This model is derived from first principles, and the results are compared with other models. The implications of these findings are discussed, and a description of future work based on these findings is presented.

Effect of hydrogen-gas pressure on threshold of hydrogen-induced crack growth for carbon steel JIS-SM490B, low-alloy steel JIS-SCM435 and stainless steel JIS-SUS304

Effect of hydrogen-gas pressure on threshold of hydrogen-induced crack growth for carbon steel JIS-SM490B, low-alloy steel JIS-SCM435 and stainless steel JIS-SUS304

Modeling of the Slow Crack Growth Caused by Internal Hydrogen in Metals

Hydrogen-induced slow crack growth exhibits, in general, three distinct stages of crack growth kinetics, and stages I and II are controlled by hydrogen diffusion. A model that describes the kinetics of crack growth caused by internal hydrogen (in stages I and II) is proposed on the basis of the linear elastic fracture mechanics, stress-induced hydrogen diffusion theory and hydrogen-enhanced decohesion mechanism for hydrogen-induced cracking. The model predicts the crack growth rate da/dt for both stages I and II as a function of the stress intensity factor KI and the initial level of hydrogen concentration. Some experimental data reported in the literature are used to validate the model and good agreement is obtained.

115 MPa水素ガス中におけるSCM435の水素誘起き裂進展下限界値<i>K</i><sub>I,H</sub>を求める試験方法

115 MPa水素ガス中におけるSCM435の水素誘起き裂進展下限界値<i>K</i><sub>I,H</sub>を求める試験方法

Comprehensive Understanding of Ductility Loss Mechanisms in Various Steels with External and Internal Hydrogen

Hydrogen-induced ductility loss and related fracture morphologies are comprehensively discussed in consideration of the hydrogen distribution in a specimen with external and internal hydrogen by using 300-series austenitic stainless steels (Types 304, 316, 316L), high-strength austenitic stainless steels (HP160, XM-19), precipitation-hardened iron-based super alloy (A286), low-alloy Cr-Mo steel (JIS-SCM435), and low-carbon steel (JIS-SM490B). External hydrogen is realized by a non-charged specimen tested in high-pressure gaseous hydrogen, and internal hydrogen is realized by a hydrogen-charged specimen tested in air or inert gas. Fracture morphologies obtained by slow-strain-rate tensile tests (SSRT) of the materials with external or internal hydrogen could be comprehensively categorized into five types: hydrogen-induced successive crack growth, ordinary void formation, small-sized void formation related to the void sheet, large-sized void formation, and facet formation. The mechanisms of hydrogen embrittlement are broadly classified into hydrogen-enhanced decohesion (HEDE) and hydrogen-enhanced localized plasticity (HELP). In the HEDE model, hydrogen weakens interatomic bonds, whereas in the HELP model, hydrogen enhances localized slip deformations. Although various fracture morphologies are produced by external or internal hydrogen, these morphologies can be explained by the HELP model rather than by the HEDE model.

Unified evaluation of hydrogen-induced crack growth in fatigue tests and fracture toughness tests of a carbon steel

To investigate the effect of hydrogen on fatigue life characteristics and crack growth behaviors through the entire fatigue life of a carbon steel, tension-compression fatigue tests and elasto-plastic fracture toughness tests were conducted in a hydrogen gas environment under the pressures of 0.7 and 115MPa. The fatigue tests revealed that the fatigue life and fracture morphology vary drastically with the hydrogen gas pressure. This study demonstrates that such differences can be explained by the combination of fatigue crack growth properties and fracture toughness properties in hydrogen gas at each pressure.

Hydrogen diffusivity and tensile-ductility loss of solution-treated austenitic stainless steels with external and internal hydrogen

The effects of external and internal hydrogen on the slow-strain-rate tensile (SSRT) properties at room temperature were studied for ten types of solution-treated austenitic stainless steels containing a small amount of additive elements. The hydrogen diffusivity and solubility of the steels were measured with high-pressure hydrogen gas. The remarkable tensile-ductility loss observed in the SSRT tests was attributed to hydrogen-induced successive crack growth (HISCG) and was successfully quantified according to the nickel-equivalent content (Nieq), which represents the stability of the austenitic phase. The relative reduction in area (RRA) of the steels with a larger Nieq was influenced by the hydrogen distribution, whereas that of the steels with a smaller Nieq was not. This unique trend was interpreted with regard to the hydrogen distribution and fracture morphology (HISCG or microvoid coalescence).

炭素鋼の高圧水素ガス中SSRT試験における水素誘起表面き裂進展に及ぼすパーライトの影響

炭素鋼の高圧水素ガス中SSRT試験における水素誘起表面き裂進展に及ぼすパーライトの影響

Critical assessment 19: mechanisms of hydrogen induced cracking in pipeline steels

Hydrogen induced cracking (HIC) remains a prominent issue for oil and gas exploration in challenging environments. This assessment discusses HIC in light of hydrogen transport through pipeline steel microstructures and crack initiation and propagation processes. While there has been significant research in hydrogen permeation through steel alloys, additional understanding is necessary in microstructures specific to pipeline steels. Furthermore, a standard model for crack initiation and propagation processes needs to be established; a fracture mechanics based model, which has been used by some researchers, is presented in the present paper to predict crack propagation. Advanced characterisation techniques can help elucidate mechanisms of hydrogen induced crack growth. Ultimately, linking hydrogen transport and cracking processes during HIC will enable optimised alloy and microstructure design.

Effect of inside diameter on design fatigue life of stationary hydrogen storage vessel based on fracture mechanics

Design fatigue life of stationary hydrogen storage vessel constructed of the practical materials of low alloy steels was analyzed based on fracture mechanics in hydrogen and air of 45, 85 and 105 MPa using cylindrical model with inside diameter (Di) of 150, 250 and 350 mm. Design fatigue life of five typical model materials was also analyzed to discuss the effect of Di on the design fatigue life by hydrogen-induced crack growth of the vessel. KIC of all the practical materials qualified the leak before burst. Design fatigue life generally increased slightly with increasing Di in air, while design fatigue life by KIH was much shorter than that in air. Hydrogen influence on design fatigue life increased with increasing Di due to that KI at initial crack increased with increasing Di. The design fatigue life data of the model materials under the conditions of Di, pressure, ultimate tensile strength, KIH, fatigue crack growth rate and regulations in both hydrogen and air were proposed quantitatively for materials selection and development for stationary hydrogen storage vessel.

Hydrogen Fatigue-resisting Carbon Steels

Hydrogen fatigue-resistant carbon steels that show dramatically reduced hydrogen-induced fatigue crack growth acceleration were successfully produced, as results of combining the addition of carbide-forming elements and the refinement of ferrite crystal grains. When carbon steels with the carbide-forming elements Vanadium (V), Titanium (Ti) and Niobium (Nb) added individually were caliber-rolled at 833K, fine carbides (VC, TiC or NbC) were precipitated and the ferrite crystal grain size became less than or equal to 1μm.

Recent Advances in the Study of Structural Materials Compatibility with Hydrogen

Hydrogen is a ubiquitous element that enters materials from many different sources. It almost always has a deleterious effect on mechanical properties. In non-hydride-forming systems, research to date has identified hydrogen-enhanced localized plasticity and hydrogen-induced decohesion as two viable mechanisms for embrittlement. However, a fracture prediction methodology that associates macroscopic parameters with the degradation mechanisms at the microscale has not been established, as of yet. In this article, we report recent work on modeling and simulation of hydrogen-induced crack initiation and growth. Our goal is to develop methodologies to relate characteristics of the degradation mechanisms from microscopic observations and first-principles calculations with macroscopic indices of embrittlement. The approach we use involves finite element analysis of the coupled hydrogen transport problem with hydrogen-assisted elastoplastic deformation, thermodynamic theories of decohesion, and ab initio density functional theory calculations of the hydrogen effect on grain boundaries.

Morphological study of supported thin Pd and Pd–25Ag membranes upon hydrogen permeation

Morphological change of Pd and Pd–25Ag membranes supported by V–15Ni alloy upon hydrogen permeation was investigated in the temperature range 423–673 K. The supported Pd–25Ag membrane exhibited higher resistance to hydrogen-induced cracking and grain growth than the supported Pd membrane. Long-term permeation of Pd–25Ag/V–15Ni composite membrane was carried out at 573 and 673 K for 200 h. There was no strong metallic interdiffusion between the Pd–25Ag membrane and the V–15Ni support after the long-term permeation at 573 K but small amounts of oxide had formed on the surface of Pd–25Ag membrane. Whisker and fissure-oxide morphologies were dominant on the exit and entrance side of the Pd–25Ag/V–15Ni composite membrane, respectively, accompanied by severe metallic interdiffusion after the long-term permeation at 673 K. AES and FE-SEM results revealed that metallic interdiffusion and selective oxidation of vanadium were responsible for the deterioration of Pd–25Ag membrane at 673 K. Hydrogenation–dehydrogenation of Pd and Pd–25Ag membranes supported by stainless steel and V–15Ni alloy were in situ examined by an optical microscope. The formation of hydride was uniform in the Pd/V–15Ni sample but localized in the Pd–25Ag/V–15Ni sample, suggesting that the hydrogen transfer through interface was strongly dependent on the composition of Pd alloy membranes. As for the stainless steel supported samples, both Pd and Pd–25Ag membranes had fractured.

Influence of Cyclic Preloading on the Hydrogen Degradation of Materials

We present the results of numerical analysis of the influence of the mode of preliminary cyclic loading on hydrogen-induced crack growth in high-strength steel with regard for the stress-strain state and diffusion of hydrogen. The elastoplastic stress-strain state at the crack tip under cyclic loading followed by monotonic loading is simulated for the case of high strains. The diffusion of hydrogen at the crack tip is modeled by taking into account the evolution of the stress-strain state from postcyclic compression to tension in the course of hydrogenation. It is shown that the accumulation of hydrogen in the process zone depends on the distribution of residual stresses induced by cyclic preloading.