Hydrogen Embrittlement Behavior Research Articles

Hydrogen Embrittlement Behavior of X42 Pipeline Steel in Gaseous Hydrogen with Different Pressures

Hydrogen Embrittlement Behavior of X42 Pipeline Steel in Gaseous Hydrogen with Different Pressures

Experimental Study on Hydrogen Embrittlement Behavior of X80 and X70 Pipeline Steels Evaluated by Hydrogen Permeation and Slow Strain Rate Tensile Tests

Experimental Study on Hydrogen Embrittlement Behavior of X80 and X70 Pipeline Steels Evaluated by Hydrogen Permeation and Slow Strain Rate Tensile Tests

Hydrogen-induced cracking behaviors of Ni–Cr–Mo-based superalloy fabricated by wire arc additive manufacturing under different solution temperature

The hydrogen embrittlement behavior of Ni–Cr–Mo-based superalloy fabricated by wire arc additive manufacturing (WAAM) with or without solution treatment was investigated by electrochemical hydrogen charging. The results show that the dissolution of the Laves phase promotes the precipitation of the δ phase in the matrix of WAAM superalloy after solution treatment at 980 °C. When the solution temperature goes up to 1080 °C, the large Laves phase disappears and only MC exists in the matrix. The interfaces between the Laves phase/δ phase and matrix generally could act as hydrogen traps, which would reduce the motion of hydrogen and lead to high hydrogen embrittlement resistance of the WAAM and ST-980 °C samples. However, hydrogen mainly accumulates on grain boundaries in the ST-1080 °C due to the disappearance of the Laves phase and δ phase. Hydrogen-induced intergranular brittle fracture occurs during the slow strain rate tensile test and the ST-1080 °C samples exhibit higher hydrogen embrittlement susceptibility than that of the WAAM and ST-980 °C samples.

The regulation of dislocation and precipitated phase improving hydrogen embrittlement resistance of pipeline steel in high pressure hydrogen environment

In this study, the hydrogen embrittlement behavior of quenched pipeline steel tempered at 550 °C to 650 °C in a high-pressure hydrogen environment was analyzed. Hydrogen permeation tests and microstructural analyses indicated that the dislocation density of the steel decreases with increasing tempering temperature, while precipitates gradually nucleate and grow. These hydrogen traps interact with hydrogen atoms, resulting in significantly higher diffusible hydrogen content in steel tempered at 550 °C compared to that tempered at 600 °C and 650 °C. Fatigue crack growth (FCG) test results show that steel tempered at 600 °C and 650 °C exhibits significantly better hydrogen embrittlement resistance than steel tempered at 550 °C. This is primarily due to the combined effect of the high hydrogen concentration, high dislocation density and low nano carbide content in the steel tempered at 550 °C, which inhibits dislocation slip and emission, leading to high crack tip stress and rapid crack propagation. In contrast, the low dislocation density and and dispersed nano carbides in steel tempered at 600 °C and 650 °C facilitate some dislocation slip and emission, result in crack tip stress relaxation and reduced crack propagation rate. Properly controlling the initial dislocation density and increasing the density of irreversible hydrogen traps can enhance the strength of materials while improving their resistance to hydrogen embrittlement.

Hydrogen Embrittlement Behavior of API X70 Linepipe Steel under Ex Situ and In Situ Hydrogen Charging.

This study investigates the hydrogen embrittlement behavior of API X70 linepipe steel. The microstructure was primarily composed of a dislocation-rich bainitic microstructure and polygonal ferrite. Slow strain-rate tests (SSRTs) were performed under both ex situ and in situ electrochemical hydrogen charging conditions to examine the difference between hydrogen diffusion and trapping behaviors. The ex situ SSRTs showed almost the same tensile properties as air and a limited brittle fracture confined to near the surface. In contrast, the in situ SSRTs showed an abrupt failure after the maximum tensile load, leading to a brittle fracture across the entire fracture surface with stress-oriented hydrogen-induced cracking (SOHIC). The crack trace analysis results indicated that SOHIC propagation paths were influenced by localized hydrogen accumulation due to high-stress fields. As a result, the dominant hydrogen embrittlement mechanisms, such as hydrogen-enhanced localized plasticity (HELP) and hydrogen-enhanced decohesion (HEDE), changed. These findings provide critical insights into the microstructural factors affecting hydrogen embrittlement, which are essential for the design of hydrogen-resistant steels in hydrogen infrastructure applications.

Hydrogen and vacancy concentrations in [formula omitted]-iron under high hydrogen gas pressure and external stress: A first-principles neural network simulation study

The metal-hydrogen-vacancy interaction in α-iron is crucial for understanding hydrogen embrittlement behavior and developing reliable materials for green gaseous hydrogen applications; however, it remains underexplored, particularly in contexts involving external stress and high hydrogen gas pressure. In this study, we performed quantitative analyses of metal-vacancy–hydrogen interactions in α-iron, measured by hydrogen solubility and the thermodynamics of vacancy–hydrogen complexes, under such challenging conditions using a reliable first-principles neural network potential. High hydrogen gas pressures reaching up to 2 GPa were investigated. As the atomic concentration surpasses approximately 0.01, hydrogen solubility is dominated by hydrogen-induced lattice distortion (primarily volumetric expansion) and the interactions between hydrogen atoms within the metal matrix, resulting in significant deviations from Sieverts’ law. Our results reveal a significant effect of shear stress on hydrogen solubility, deviating from previously used equations. Moreover, the influence of external stress on the thermodynamics of the vacancy–hydrogen complex, particularly vacancy formation free energy, is uniquely characterized by hydrogen solubility, regardless of the external stress magnitude. It thereby offers a rapid method to estimate the vacancy properties under external stress based on readily accessible external-stress-free data.

Effect of I-phase formation on hydrogen embrittlement behaviour of as-cast Mg-8 wt%Li based alloys

By performing microstructural characterization, tensile testing and failure analysis, the effects of electrochemical H-charging on microstructure and mechanical behaviour of two as-cast Mg-8Li (in wt%) based alloys were investigated and compared. Due to the in-situ formation of I-phase, the failure elongation ratio for Mg-8Li-6Zn-1Y alloy was 31.2 % and its hydrogen embrittlement (HE) susceptibility was about 1/4 that of Mg-8Li alloy after H-charging for 24 h. Moreover, the preferential location of H-induced pores transferred from two matrix phases to I-phase/matrix eutectic pockets due to the preferential H absorption of I-phase, resulting in the higher HE resistance of Mg-8Li-6Zn-1Y alloy.

Hydrogen embrittlement in Nickel oligocrystals: Experimentation and crystal plasticity-phase field fracture modeling

This work investigates the hydrogen embrittlement (HE) behavior of Nickel-201 alloy using experimental and numerical approaches. In experimentation, the effect of electrochemical hydrogen charging on the deformation behavior of tensile oligocrystals is investigated at different strain rates. Irrespective of the strain rate levels, all the hydrogen-charged tensile oligocrystals exhibited intergranular (IG) fracture exclusively along the random high-angle grain boundaries (RHAGBs). At the same time, no crack was observed along the coincident site lattice (CSL) Σ3 type grain boundaries. The absence of an interconnected grain boundary network, lower stress levels, and insensitivity of H-induced IG fracture to the strain rate levels of investigated FCC oligocrystals (with low lattice hydrogen diffusion coefficient) established the insignificance of dynamic H-redistribution toward HE. In numerical simulations, a crystal plasticity-phase field fracture finite element model simulates the macroscopic tensile response and corresponding microscopic fracture evolution behavior for hydrogen-free and hydrogen-charged tensile oligocrystals. The experimental results corroborated by numerical simulations, validate that the reduction in fracture energy of RHAGBs, induced by hydrogen segregation through thermodynamic equilibrium during hydrogen charging prior to deformation, is the dominating factor governing HE.

A Review on hydrogen embrittlement behavior of steel structures and measurement methods

Hydrogen can be found within metals under a variety of industrial and environmental conditions. Hydrogen-metal interactions can take place through hydrogen embrittlement, hydrogen sulfide corrosion, or hydrogen absorption. Steel and other metals that are exposed to hydrogen may experience a difficulty known as hydrogen embrittlement that affects their mechanical properties. The material's ductility and toughness may be reduced as a result of this phenomena, it also increasing the risk of brittle fracture. In steel, atomic hydrogen mainly diffuses into the microstructure of the steel, causing hydrogen embrittlement. Localized weakening of the bonds between the metal atoms might result from hydrogen atoms occupying interstitial positions in the metal lattice. Especially when under stress, this may lead to a more susceptible to fracture and cracking. Concerns with hydrogen embrittlement arise in sectors like aerospace and oil and gas that use high-strength steels. If not appropriately handled, it may result in catastrophic failures. Use of hydrogen-resistant alloys, appropriate heat treatments, and protection from conditions that promote hydrogen uptake are examples of preventive measures. This literature review paper covers the definition of hydrogen embrittlement (HE), mechanisms causing HE, measurement of hydrogen concentration and preventive measures that restrict hydrogen diffusion to the steel.

Enhanced hydrogen embrittlement resistance of additive manufacturing Ti-6Al-4V alloy with basket weave structure

The hydrogen embrittlement (HE) behavior of tungsten inert gas arc additive manufacturing (AM) Ti-6Al-4V alloy was studied through tensile tests with/without hydrogen charging. The influence of hydrogen on the microstructure and crack propagation of AM Ti-6Al-4V alloy was investigated. The results indicated that the AM Ti-6Al-4V alloy with a basket weave structure alleviated local stress at grain boundaries during deformation, thus avoiding intergranular cracking and brittle fracture. The AM alloy displayed less HE susceptibility than that of the wrought alloy, which was due to the basket weave structure hindering the propagation of hydrogen-induced cracks, thereby improving the HE resistance.

Influence of Nb on the hydrogen-assisted cracking behaviour in multiphase stainless steel: Phase fractions, stacking fault energies, and nanosized NbC precipitation

Nb alloying has been reported to deteriorate the hydrogen embrittlement resistance of multiphase steels, which contrasts to the case of single-phase metallic materials. This study clarifies the impact of Nb alloying on the hydrogen embrittlement behaviour of a novel multiphase stainless steel. The findings revealed a 17 % reduction in the hydrogen embrittlement sensitivity upon Nb incorporation. It was found that higher austenite fractions in the Nb-bearing steels impeded hydrogen ingress. The austenite phase in such Nb-bearing steels possesses a higher stacking fault energy, thereby delaying martensitic transformation and crack initiation. The precipitation of nanometre-sized NbC in the matrix obstructed hydrogen diffusion, which indirectly inhibited crack initiation and propagation.

Effect of heat treatment on hydrogen embrittlement susceptibility of Al0.25CoCrFeNi high entropy alloy

In this study, the influences of annealing and aging treatments on the hydrogen embrittlement (HE) behavior of the cryo-rolled Al0.25CoCrFeNi high entropy alloy (HEA) were investigated through tensile tests and electrochemical hydrogen charging experiments. The results found that the aged sample showed high strength but was more susceptible to HE. A trade-off between the strength and HE resistance was achieved in the annealed + aged sample. Electron backscatter diffraction analysis and fracture characteristics were performed to clarify the HE mechanism. The high dislocation density and aggregated second phase along the grain boundaries in the aged sample were the important factors to help the initiation of HE crack, and then increasing the HE susceptibility. The annealed + aged sample with low dislocation density and aging precipitation reduced the risk of hydrogen-induced cracking and resulting in the excellent HE resistance. This work offered the method to obtain a comprehensive improvement in the strength and HE resistance of this alloy.

The Impact of Impurity Gases on the Hydrogen Embrittlement Behavior of Pipeline Steel in High-Pressure H2 Environments.

The use of hydrogen-blended natural gas presents an efficacious pathway toward the rapid, large-scale implementation of hydrogen energy, with pipeline transportation being the principal method of conveyance. However, pipeline materials are susceptible to hydrogen embrittlement in high-pressure hydrogen environments. Natural gas contains various impurity gases that can either exacerbate or mitigate sensitivity to hydrogen embrittlement. In this study, we analyzed the mechanisms through which multiple impurity gases could affect the hydrogen embrittlement behavior of pipeline steel. We examined the effects of O2 and CO2 on the hydrogen embrittlement behavior of L360 pipeline steel through a series of fatigue crack growth tests conducted in various environments. We analyzed the fracture surfaces and assessed the fracture mechanisms involved. We discovered that CO2 promoted the hydrogen embrittlement of the material, whereas O2 inhibited it. O2 mitigated the enhancing effect of CO2 when both gases were mixed with hydrogen. As the fatigue crack growth rate increased, the influence of impurity gases on the hydrogen embrittlement of the material diminished.

Effects of lattice misfit of γ/γ′ phases on hydrogen embrittlement behavior in Ni-based single crystal superalloy

The effect of γ/γ′ phase lattice misfit on hydrogen embrittlement (HE) behavior was fundamentally investigated by utilizing a Ni-based single crystal CMSX-4 superalloy with a simple microstructure that can exclude the H-trapping effects of grain boundary, c-vacancy, and misfit dislocation. Increasing isothermal aging time increased γ′ precipitate size while maintaining its volume fraction and a fully coherent interface. The magnitude of negative lattice misfit between the γ and γ′ phases increased from −0.08 to −0.22% according to γ′ precipitate coarsening, resulting in a well-developed tensile-strain field within the γ′ precipitate. The increased tensile-strain field enhanced activation energy for H-desorption in the γ′ precipitate from 31.9 to 35.1 kJ/mol. Therefore, H is preferentially distributed along the γ/γ′ interface within the γ′ precipitate even before deformation. H basically promotes the slip planarity through the H-enhanced localized plasticity (HELP) mechanism in Ni-based single crystal alloys, in which slip is the dominant deformation behavior. As the superalloy possesses a larger negative lattice misfit, H becomes trapped as diffusible-state at the tensile-strain field of the γ/γ′ interface, resulting in cuboidal brittle fracture along the {001} planes. In this process, the HELP mechanism facilitated H localization at the γ/γ′ interface. Thus, the HE behavior distinctly transitioned from HELP to an interaction between HELP and H-enhanced decohesion mechanisms (HEDE) with an increase in the magnitude of the lattice misfit. The HE behavior was investigated by correlating microstructural characterization, H-trapping behavior, and crystallographic fracture mechanism analysis.

Correlation between pre-strain and hydrogen embrittlement behavior in medium-Mn steel

In this study, we investigated the correlation between the pre-strain and hydrogen embrittlement (HE) mechanisms in medium-Mn steel. Intercritically annealed Fe-7Mn-0.2C-3Al (wt.%) steel, which showed a two-phase microstructure comprising α ferrite and γR retained austenite, was used as a model alloy. As the pre-strain level increased from 0 % to 45 %, the volume fraction of γR gradually decreased owing to the strain-induced α′ martensite transformation accompanied by an increase in dislocation density. The HE resistance decreased with increasing the pre-strain level because the sample with a higher pre-strain level revealed a higher amount of dissolved hydrogen, combined with a more extensive brittle fracture region owing to the enhanced diffusion and permeation of hydrogen from the reduced γR fraction. Additionally, the H-assisted crack in the sample without pre-strain was initiated and propagated from the γR grains when the strain-induced α′ phase was formed, because most of the dissolved hydrogen was concentrated in the γR grains, and these grains were predominantly deformed compared to the other phases. However, the pre-strained sample showed more pronounced multiple H-assisted cracking at the constituent phases, such as α and α′, because it exhibited relatively well-dispersed hydrogen atoms and reduced microstrain localization at the γR grains, due to the reduced γR fraction.

Inhibiting stress corrosion cracking of a prefabricated surface‐defective magnesium alloy thanks to biological organic components

AbstractBiomedical magnesium (Mg) alloys remain a challenge for their mainstream application, because the combination of bio‐mechanical stress and corrosive physiological environment leading to stress corrosion cracking (SCC). It is crucial to avoid the sudden brittle fracture of Mg alloys in vivo for predicting their service duration. However, the key factors, such as surface or physiological environment features, determining the origination or propagation of SCC behavior are still unclear. In the present study, a prefabricated surface defects coating was prepared by the phytic acid (PA, C6H18O24P6) conversion treatment. Four mimicking physiological media were used, ranging from simple to equivalent (Dulbecco's Modified Eagle Medium and Protein [DMEM+Pro]). The results showed that the PA film with numerous micro‐cracks provided limited protective ability in synthetic biological media. A striking finding was determined that although initial high corrosion rate of samples in DMEM+Pro led to an increased SCC nucleation, significant ductile fracture with elongation to failure (14.86%) was observed. Combined with the fracture features, the adsorption or deposition of biological composition into the tunnel of SCC cracks significantly inhibited the hydrogen embrittlement (HE) behavior. These results indicate that preventing the propagation of SCC crack by biological composition, rather than nucleation, plays a key role in avoiding the sudden fracture of Mg alloys. It provides a novel perspective to determine the non‐brittle fracture of Mg alloys for biomedical applications.

Investigation of Hydrogen Embrittlement of Haynes 617 and Hastelloy X Alloys Using Electrochemical Hydrogen Charging

This study explores the hydrogen embrittlement behaviour of two Ni-based superalloys using electrochemical hydrogen charging. Two types of tensile specimens with different geometry for the Haynes 617 and Hastelloy X alloys were electrochemically hydrogen-charged, and then a slow strain rate test was conducted to investigate the hydrogen embrittlement behaviour. Unlike the ASTM standard specimens, two-step dog-bone specimens with a higher surface-area-to-volume ratio showed higher sensitivity to hydrogen embrittlement because hydrogen atoms are distributed mostly on the surface area. On the other hand, the Haynes 617 alloy had a lower hydrogen embrittlement resistance than that of the Hastelloy X alloy due to its relatively large grain size and the presence of precipitates at grain boundaries. The Haynes 617 alloy primarily showed an intergranular fracture mode with cracks from the slip band, whereas the Hastelloy X alloy exhibited a combination of transgranular and intergranular fracture behavior under hydrogen-charged conditions.

Hydrogen embrittlement behaviors during SSRT tests in gaseous hydrogen for cold-worked type 316 austenitic stainless steel and iron-based superalloy A286 used in hydrogen refueling station

To consider an appropriate evaluation method for hydrogen compatibility, slow strain rate tensile (SSRT) tests were conducted on high strength piping materials, cold-worked type 316 austenitic stainless steel (SUS316CW) and iron-based superalloy A286, used in hydrogen stations for two years.SUS316CW, used at room temperature in 82 MPa gaseous hydrogen, contained 7.8 mass ppm hydrogen. The SSRT test of SUS316CW was conducted in nitrogen at −40 °C. The fracture surface showed dimples, and no hydrogen embrittlement behavior was observed. While, the SSRT test of SUS316CW in 70 MPa gaseous hydrogen at −40 °C showed a slight decrease in reduction area and a brittle fracture morphology in the outer layer. This was considered to be the effect of high-pressure gaseous hydrogen during the SSRT test in addition to the pre-contained hydrogen.A286, used at −40 °C in 82 MPa gaseous hydrogen, contained negligible hydrogen (0.14 mass ppm). SSRT tests were conducted at 150 °C in 70 MPa gaseous hydrogen and in air, and showed a low relative reduction in area (RRA) value. To investigate the decrease in the RRA, we switched the gas from hydrogen to air in the middle of the SSRT test and closely examined the RRA values and fracture morphology including side cracks. The hydrogen embrittlement was found to originate from the elastic deformation region. Stress cycling in the elastic deformation region also accelerated the effect of hydrogen. These were attributed to an increase in the lattice hydrogen content. While in the plastic deformation region, hydrogen trapped in the defects and hydrogen through the generated surface cracks increased the hydrogen content at the crack tips, reducing the RRA value. And there was a good correlation between the crack lengths and RRA values.Then, hydrogen embrittlement mechanism depends on the operating conditions (stress and temperature) of the material, and evaluating the hydrogen compatibility of materials by controlling their hydrogen content and strain according to the service environment is desirable.

Investigation into hydrogen assisted fracture in Nickel oligocrystals

This study investigates the hydrogen embrittlement (HE) behavior of Nickel-201 alloy using the oligocrystal approach. To comprehend the influence of microstructure toward HE, various types of tensile oligocrystals (True-oligocrystals, Quasi-oligocrystals, Identical-oligocrystals, and Bi-crystal type oligocrystals) with diverse microstructure (in terms of Schmid factor distribution and grain boundary types) are generated using a combination of heat treatment and slicing method. The electron backscatter diffraction (EBSD) analysis is used to validate the development of the desired tensile oligocrystal samples. Identical oligocrystal samples established the transition in fracture mode from ductile transgranular (TG) to brittle intergranular (IG), solely driven by hydrogen uptake. Post-tensile deformation analysis validated the hydrogen-induced IG fracture initiation and propagation along the random high-angle grain boundaries (RHAGBs) only. Bi-crystal type oligocrystals with low angle grain boundaries (LAGBs) and coincident-site lattice (CSL) Σ3 grain boundaries exhibited resistance to hydrogen-induced intergranular fracture, thus establishing the ‘special’ nature of these grain boundaries against the HE under current testing conditions.

Study of hydrogen embrittlement behavior and mechanism of Ti-2.5Al-2Zr-1Fe by slow strain rate method

The Ti-2.5Al-2Zr-1Fe used as hull structural material, is susceptible to hydrogen embrittlement induced by corrosion and hydrogen evolution in marine environments. Considering the long-term service of ships, the hydrogen embrittlement behavior under slow strain rate is crucial for evaluating the alloy’s service performance and ensuring long-term ship structural safety. In order to investigate the hydrogen embrittlement mechanism of Ti-2.5Al-2Zr-1Fe alloy under slow strain rate conditions, this study combines slow tension and constant displacement loading techniques to systematically evaluate the attenuation of mechanical properties and the dynamic changes in hydrogen embrittlement sensitivity of hydrogen-containing Ti-2.5Al-2Zr-1Fe alloy. Employing scanning electron microscopy (SEM), we thoroughly analyze the microstructural features of fracture surfaces. Meanwhile, the close correlation between the brittle zone at the fracture site and the macroscopic distribution of hydrogen atoms is elucidated by using secondary ion mass spectrometry (SIMS). Additionally, theoretical analysis based on diffusion equations reveals a notable increase in hydrogen diffusion distance within the Ti-2.5Al-2Zr-1Fe alloy as hydrogen charging time increases. Further, using the dislocation-hydrogen interaction model, we derive a critical strain rate threshold <inline-formula><tex-math id="M1">\begin{document}$ {\varepsilon _0} = {{\left( {30RT} \right)} {/ } {\left( {\rho DE} \right)}} $\end{document}</tex-math></inline-formula> for dislocation-mediated hydrogen transport in titanium alloys. When the externally applied strain rate <i>ε</i> falls below this threshold, dislocations efficiently capture and transport hydrogen atoms, enhancing hydrogen diffusion depth and significantly augmenting the alloy’s hydrogen embrittlement sensitivity, thereby accelerating material embrittlement. The Vickers-hardness (HV) test further elucidates the dual nature of hydrogen’s influence on titanium alloy properties: although moderate hydrogen content slightly enhances surface hardness, exceeding a specific threshold leads to a major negative influence on plasticity, far exceeding the benefits of surface hardening, resulting in a substantial decline in overall mechanical performance. To comprehensively decipher the hydrogen embrittlement mechanism of Ti-2.5Al-2Zr-1Fe alloy, transmission electron microscopy (TEM) is employed to analyze the phase composition in regions of high hydrogen concentration, crack tips, and their vicinities. The analysis results indicate that no direct precipitation of hydrides is observed; instead, hydrogen atoms preferentially accumulate in the <i>β</i>-phase, prompting microcrack propagation along <i>β</i>-phase boundaries. According to the aforementioned experimental data and microstructural analysis, we propose that the hydrogen embrittlement mechanism in Ti-2.5Al-2Zr-1Fe alloy is primarily governed by the HEDE mechanism. Furthermore, when the strain rate falls below <i>ε</i><sub>0</sub>, it synergizes with the dislocation-mediated hydrogen transport mechanism, vastly expanding the influence scope of the HEDE mechanism and exacerbating the alloy’s hydrogen embrittlement sensitivity.