High-pressure Hydrogen Gas Research Articles

Nickel-Catalyzed Enantioselective Reductive Amination of Ketones with Both Arylamines and Benzhydrazide.

An asymmetric reductive amination of ketones using both arylamines and benzhydrazide in the presence of nickel catalysts was developed. A one-pot synthesis of tetrahydroquinoxalines was also developed starting directly from α-ketoaldehydes and 1,2-diaminobenzene. Formic acid was used as a safe and economic surrogate for high-pressure hydrogen gas. Strongly σ-donating bis(alkylphosphine)s are crucial ancillary ligands for both stereoselective hydride insertion and decarboxylation of the formate.

Effect of strain rate on hydrogen embrittlement susceptibility of twinning-induced plasticity steel pre-charged with high-pressure hydrogen gas

The effects of tensile strain rate on the hydrogen-induced mechanical and microstructural features of a twinning-induced plasticity (TWIP) steel were investigated using a Fe-23Mn-0.5C steel with a saturated amount of hydrogen. To obtain a homogeneous hydrogen distribution, high-pressure hydrogen gas pre-charging was performed at 423 K. Similar to previous studies on hydrogen embrittlement, the deterioration in the tensile properties became distinct when the strain rate was decreased from 0.6 × 10−3 to 0.6 × 10−4 s−1. In terms of microstructural features, hydrogen-precharging decreased the thickness of deformation twin plates, and it localized dislocation slip. Moreover, facets of the hydrogen-induced quasi-cleavage feature on the fracture surface became smoother with decreasing strain rate. In this study, we proposed that a combined effect of hydrogen segregation, slip localization, and thinning of twin plates causes the hydrogen embrittlement of TWIP steels, particularly at a low strain rate.

Determination of hydrogen compatibility for solution-treated austenitic stainless steels based on a newly proposed nickel-equivalent equation

The nickel-equivalent equation for the materials selection of solution-treated austenitic stainless steels in present Japanese regulations does not consider nitrogen, which can improve resistance to hydrogen embrittlement. For the authorization of various austenitic stainless steels for use in high-pressure hydrogen gas and based on investigations of eight types of solution-treated austenitic stainless steels, this paper presented a newly proposed nickel-equivalent equation considering nitrogen. After tensile testing to the true strain ε of 0.3 in air at both room temperature (RT) and 228 K, the strain-induced martensite content VM was measured by a saturation magnetization technique; the VM correlated well with the proposed nickel-equivalent equation. For slow strain rate tensile (SSRT) testing in hydrogen gas at RT, the relative reduction in area (RRA) was consistently lower with increased VM for ε = 0.3 at 228 K. This suggests that the austenitic phase stability is crucial in determining the RRA of the present austenitic stainless steels and the RRA was successfully quantified by the proposed equation.

Hydrogen Embrittlement of Two Austenitic High-Manganese Steels Using Tensile Testing under High-Pressure Gaseous Hydrogen

The hydrogen embrittlement of two austenitic high-manganese steels was investigated using tensile testing under high-pressure gaseous hydrogen. The test results were compared with those of different kinds of austenitic alloys containing Ni, Mn, and N in terms of stress and ductility. It was found that the ultimate tensile stress and ductility were more remarkably decreased under high-pressure gaseous hydrogen than under high-pressure gaseous argon, unlike the yield stress. In the specimens tested under high-pressure gaseous hydrogen, transgranular fractures were usually observed together with intergranular cracking near the fracture surface, whereas in those samples tested under high-pressure gaseous argon, ductile fractures mostly occurred. The austenitic high-manganese steels showed a relatively lower resistance to hydrogen embrittlement than did those with larger amounts of Ni because the formation of deformation twins or microbands in austenitic highmanganese steels probably promoted planar slip, which is associated with localized deformation due to gaseous hydrogen.

Analysis of fatigue behaviour of stainless steels under hydrogen influence

Three stainless steels – ASTM 304, 316 and 316L - used in hydrogen utilization equipment are under investigation at conditions of tension-compression, rotating-bending and fretting fatigue. Fatigue tests are carried out with hydrogen charged and uncharged specimens. Hydrogen charging includes cathodic type of charging and exposure to high pressure hydrogen gas. The experiments under rotating bending and tensioncompression fatigue are conducted under different frequencies in three different laboratories: at The University of Chemical Technology and Metallurgy, Sofia, Bulgaria; at Sandia National Laboratory, California and The University of Tufts, Medford, Massachusetts, USA; The HYDROGENIUS Institute at Kyushu University, Japan. The fretting fatigue tests are presented by The HYDROGENIUS Institute at Kyushu University, Japan. The obtained results are presented in Wohler curves complemented by plots Short fatigue crack length– Number of cycles and “Tangential force coefficient–Stress amplitude”. The found fatigue characteristics are analyzed and compared at different loading conditions, showing the best performance of Steel 316L.

Optimization of compressed hydrogen gas cycling test system based on multi-stage storage and self-pressurized method

Hydrogen gas cycling test can provides stress factors associated with rapid and simultaneous interior pressure and temperature swings and infusion of hydrogen into materials; therefore, it is considered as an effective method to detect the safety of the compressed hydrogen storage system. However, the energy consumption of gas cycling test is high. In order to reduce energy consumption, an optimization gas cycling test system was designed based on multi-stage storage and self-pressurized method in this paper. A dynamic simulation model which considers the process of refueling, pressure control, pre-cooling and discharging was also established to calculate the energy consumption. Using the model, the energy consumption of different system with different storage stages, different pressure, and different volumes was calculated. The results show that with the increase of gas storage stages, total energy consumption of the system decreases, but taking into account the complexity of the system, the stages should be less than three; In the range of 20–50 MPa and 1–4 m3, lower pressure and smaller volume of low pressure tank can not only reduce the gas the construction cost, but also reduce the energy consumption; In the range of 45–60 MPa and 1–3 m3, the effect of medium pressure tank on the energy consumption is not significant. This study provides a new optimization design method for compressed hydrogen cycling test system, has an important significance in development of high pressure hydrogen gas cycling test.

FE analysis of hydrogen diffusion around a crack tip in an austenitic stainless steel

Hydrogen-assisted cracking (HAC) is a coupled phenomenon between crack growth rate and hydrogen diffusion to the region ahead of crack tip. To understand the cracking mechanism and to control or predict the HAC rate, knowledge of hydrogen diffusion around a crack tip is essential. Metastable austenitic stainless steels can be severely embrittled by hydrogen due to strain-induced α′ martensite transformation around crack tip, as the hydrogen diffusivity in α′ martensite is much higher than in γ austenite while the solubility is lower. However, the effect of induced α′ martensite on local diffusion of hydrogen around a loaded crack tip has not been intuitively demonstrated. This study first reveals the quantitative relations of hydrogen diffusivity and solubility with induced α′ martensite amount, and then performs FE analysis of hydrogen diffusion around a crack tip in a 304L ASS cylinder storing high pressure gaseous hydrogen with considering the combined effect of α′ martensite transformation and hydrostatic stress on diffusion. The hydrostatic stress exhibits a peak value at a distance away from crack tip, while the peak α′ martensite volume fraction locates at the crack tip. Compared to the analysis only considering stress effect, the presence of induced α′ martensite can not only significantly accelerate the hydrogen transport to the critical region ahead of crack tip, but also markedly elevate the level that the peak hydrogen concentration reaches. The peak hydrogen concentration doesn't locate at the peak hydrostatic stress site as generally expected, but at the site in the γ austenite-rich region abutting the α′ martensite-rich region at crack tip vicinity, because this site possesses very high hydrogen solubility and close to the high hydrogen diffusivity region, consequently accommodating the hydrogen getting off the α′ martensite diffusion “highway”.

A parametric study on exergetic sustainability aspects of high-pressure hydrogen gas compression

This paper presents a parametric study on exergetic sustainability aspects of high-pressure-hydrogen gas compression process in terms of exergy. In this regard, a single stage, two-stage, three-stage and four-stage-hydrogen gas compression processes have been considered to make a parametric evaluation in terms of the exergetic sustainability parameters including i) exergetic efficiency, ii) waste exergy ratio, iii) exergy recoverability ratio, iv) exergy destruction ratio, v) environmental effect factor, vi) exergetic sustainability index. Here, hydrogen is assumed to be a real gas because of higher pressures, and therefore, its compressibility factor is taken into account thorough the calculations. Accordingly, it is noticed that increasing stage number (ranging 1 to 4) and hydrogen gas inlet pressure (from 1 to 200 bar) decrease waste exergy ratio (from 0.853 to 0.058) and environmental effect factor (from 5.789 to 0.061) while going up exergetic sustainability index (from 0.173 to 16.337). However, increasing compressor-outlet pressure of hydrogen gas (ranging from 200 to 900 bar) reduces exergetic sustainability index (from 7.472 to 1.069) while going up waste exergy ratio (from 0.118 to 0.483), exergy destruction ratio (from 0.089 to 0.253), environmental effect factor (from 0.134 to 0.936), and exergy recoverability ratio (from 0.029 to 0.230).

SCM435 鋼陰極水素チャージ試験片の SSRT による水素脆性評価

Evaluation test of high-pressure hydrogen gas should be carried out more simplified. As an alternative approach in high-pressure hydrogen gas test, to simulate the hydrogen gas environment SSRT was performed with cathodically charged. Specimen was used a low-alloy steel, SCM435 with the tensile strength of 1000 MPa. The tensile properties was evaluated with cathodic charging with 3%NaCl solution and the current density of 50～600A/m2 . Values of RRA obtained by the tests at cathode current density of 400A/m2 are equivalent to those in the 35MPa hydrogen gas. In addition, an amount of diffusible hydrogen equivalent to that in high-pressure hydrogen gas was obtained by increasing the current density. Therefore, this approach is able to simulate the SSRT conducted in high-pressure hydrogen gas environment.

高圧水素ガス環境中で使用される金属部品の強度設計(<特集>水素社会実現に向けた製品・技術開発)

高圧水素ガス環境中で使用される金属部品の強度設計(<特集>水素社会実現に向けた製品・技術開発)

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

オーステナイト系ステンレス鋼の高圧水素ガス中 SSRT 試験における微小き裂の発生および進展挙動

オーステナイト系ステンレス鋼の高圧水素ガス中 SSRT 試験における微小き裂の発生および進展挙動

安全性と経済性を考慮した高圧水素部材の強度設計法

安全性と経済性を考慮した高圧水素部材の強度設計法

70 MPa水素ステーション実証試験で使用されたプレクーラー冷却パイプの事例解析

The case study on cooling pipe of pre-cooler, which had been used on a verification test of 70 MPa hydrogen station, was carried out. Cooling pipe consisted of main pipe, mechanical joint pipe and mechanical joint. Main pipe and mechanical joint pipe were joined by TIG welding. Chemical composition analysis, microstructure observation and Vickers hardness measurement showed that the main pipe and the mechanical joint pipe were manufactured from SUS316L, and that the filler metal of TIG welding was 316L. Round specimens were machined out from main pipe to investigate tensile properties of the base metal. On the other hand, round specimens and square specimens having reinforcement were machined out form the weld joint. Using three types of specimens, slow strain rate tests were conducted in 0.1 MPa nitrogen gas and 115 MPa hydrogen gas at −40 °C. Reductions of area for the base metal round specimen, the weld joint round specimen and the weld joint square specimen were 83.5, 71.3 and 81.4 % in nitrogen gas, whereas the values were 60.1, 61.3 and 40.1 % in hydrogen gas. That is, reductions of area for three types of specimens were smaller in hydrogen gas than in nitrogen gas. Dimples were formed on fracture surfaces of three types of specimens in nitrogen gas, whereas dimples and quasi-cleavages were formed in hydrogen gas. These results suggest that cooling pipe of pre-cooler can be “embrittled” in high-pressure hydrogen gas at low temperature.

高圧水素ガス透過法で得られた SCM435 鋼の水素透過挙動

高圧水素ガス透過法で得られた SCM435 鋼の水素透過挙動

固体高分子形水電解セルからのガスリークの解析

To commercialize high-pressure hydrogen gas by solid polymer water electrolysis (SPWE), SPWE cell must insure its sealing technology. However, electrochemical cell like SPWE cell involve soft material such as polymer electrolyte membrane (PEM), which make sealing difficult. There are a few reports discussing standard of sealing. This study takes up possible physical parameters affecting gas-leakage from SPWE cell and conducts gas-tightness test and load measurement between sealing surface by pressure-sensitive-film. Analyzing which factor dominantly impacts the leakage with using Taguchi method, the result suggests that cathode packing material, surface roughness of PEM and O-ring hardness yields large impact on the leakage. Measuring the load of O-ring in cathode side by pressure-sensitive-film, the significant parameter is only O-ring hardness. The result of gas-leakage and the load of O-ring have a weak correlation. Observing surface roughness of PEM, Nafion424 has anisotropic roughness, which causes bad sealing of the cell. On the one hand, Nafion324 which has isotropic roughness performs good sealing.

Criteria for determining hydrogen compatibility and the mechanisms for hydrogen-assisted, surface crack growth in austenitic stainless steels

To establish novel criteria for determining the hydrogen compatibility of austenitic stainless steels, as well as to elucidate the mechanisms for hydrogen-assisted surface crack growth (HASCG), slow strain rate tensile (SSRT), elasto-plastic fracture toughness (JIC), fatigue crack growth and fatigue life tests were performed on Types 304, 316 and 316L steels in high-pressure hydrogen gas. As a criterion for the use of austenitic stainless steels with lower austenitic stability in hydrogen gas, a reduction in area (RA) in hydrogen gas, φH⩾57%, or a relative reduction in area, RRA⩾0.68, is proposed to ensure that there is no degradation in tensile strength by hydrogen. Observation of fracture surface morphologies and crack growth behaviours demonstrated that, in high-pressure hydrogen gas, SSRT surface crack grew via the same mechanism as for JIC crack and fatigue crack, i.e., these cracks successively grew with a sharp shape under the loading process, due to a localized slip deformation near the crack tip. Based on the elucidated HASCG mechanism, total elongation in hydrogen gas, δH⩾10%, or, φH⩾10%, is also introduced as another criterion.

Hydrogen Environment Embrittlement on Austenitic Stainless Steels from Room Temperature to Low Temperatures

Hydrogen environment embrittlement (HEE) on austenitic stainless steels SUS304, 304L, and 316L in the high pressure hydrogen gas was evaluated from ambient temperature to 20 K using a very simple mechanical properties testing procedure. In the method, the high- pressure hydrogen environment is produced just inside the hole in the specimen and the specimen is cooled in a cooled-alcohol dewar and a cryostat with a GM refrigerator. The effect of HEE was observed in tensile properties, especially at lower temperatures, and fatigue properties at higher stress level but almost no effect around the stress level of yield strength where almost no strain-induced martensite was produced. So, no effect of HEE on austenitic stainless steels unless the amount of the ferrite phase is small.

Reconstruction of energy spectra of neutrino beams independent of nuclear effects

We propose a new technique that enables an event-by-event selection of neutrino-hydrogen interactions in multinuclear targets and thereby allows application of hydrogen as targets in experiments with neutrino beams without involving cryogenics or high pressure hydrogen gas. This technique could significantly improve the reconstruction of the neutrino energy spectra. Since it allows a separation between hydrogen and the accompanying nuclei, this technique also enables us to measure nuclear effects in neutrino interactions directly.

Effects of microstructure banding on hydrogen assisted fatigue crack growth in X65 pipeline steels

Banded ferrite–pearlite X65 pipeline steel was tested in high pressure hydrogen gas to evaluate the effects of oriented pearlite on hydrogen assisted fatigue crack growth. Test specimens were oriented in the steel pipe such that cracks propagated either parallel or perpendicular to the banded pearlite. The ferrite–pearlite microstructure exhibited orientation dependent behavior in which fatigue crack growth rates were significantly lower for cracks oriented perpendicular to the banded pearlite compared to cracks oriented parallel to the bands. The reduction of hydrogen assisted fatigue crack growth across the banded pearlite is attributed to a combination of crack-tip branching and impeded hydrogen diffusion across the banded pearlite.