scholarly journals Review and Assessment of the Effect of Hydrogen Gas Pressure on the Embrittlement of Steels in Gaseous Hydrogen Environment

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 637
Author(s):  
Thorsten Michler ◽  
Ken Wackermann ◽  
Frank Schweizer
Keyword(s):  
Hydrogen Gas ◽  
Gaseous Hydrogen ◽  
Gas Pressure ◽  
Data Sets ◽  
Large Set ◽  
Test Parameter ◽  
Rate Limiting ◽  
Important Test ◽  
Pressure Hydrogen ◽  
Reaction Chain

Hydrogen gas pressure is an important test parameter when considering materials for high-pressure hydrogen applications. A large set of data on the effect of hydrogen gas pressure on mechanical properties in gaseous hydrogen experiments was reviewed. The data were analyzed by converting pressures into fugacities (f) and by fitting the data using an f|n| power law. For 95% of the data sets, |n| was smaller than 0.37, which was discussed in the context of (i) rate-limiting steps in the hydrogen reaction chain and (ii) statistical aspects. This analysis might contribute to defining the appropriate test fugacities (pressures) to qualify materials for gaseous hydrogen applications.

Fracture Properties of a Cr-Mo Ferritic Steel in High-Pressure Gaseous Hydrogen

2015 ◽  
Author(s):  
Takashi Iijima ◽  
Hisatake Itoga ◽  
Bai An ◽  
Chris San Marchi ◽  
Brian P. Somerday
Keyword(s):  
High Pressure ◽  
Threshold Stress ◽  
Crack Extension ◽  
Elastic Compliance ◽  
Hydrogen Gas ◽  
Gaseous Hydrogen ◽  
Gas Pressure ◽  
Displacement Rate ◽  
Ferritic Steels ◽  
Pressure Hydrogen

Recently, the measurement of threshold stress intensity factors for various low alloy ferritic steels was performed in high-pressure hydrogen gas, and it was revealed that the threshold for subcritical crack extension under rising displacement was lower than that for crack arrest under constant displacement. We previously examined the threshold for subcritical crack extension of ASME SA-372 Grade J ferritic steels using an unloading elastic compliance method in gaseous hydrogen at pressure up to 115 MPa, and reported that the cracking thresholds under the unloading elastic compliance method are consistent with the cracking threshold under the continuously rising displacement method. In the current study, the threshold stress intensity factor of JIS SCM 435 steel with yield strength of 700 MPa was measured using the unloading compliance method in high-pressure hydrogen gas. The roles of environmental (gas pressure) and testing (displacement rate) parameters were evaluated. The hydrogen gas pressure ranged from 10 to 115 MPa, and the displacement rate was varied between 2×10−3 and 2×10−5 mm/s. The measured values of the threshold for subcritical crack extension, KJIC,H, decreased with either increasing hydrogen gas pressure or decreasing displacement rate. When the hydrogen pressure was 115 MPa, however, the cracking threshold showed a modest dependence on displacement rate, varying from 63 to 43 MPa m1/2. These results demonstrate that the measurement conditions, such as the hydrogen pressure and the displacement rate, affect values of the subcritical cracking threshold under rising displacement.

Tribological Characterization of Polymeric Sealing Materials in High Pressure Hydrogen Gas

2010 ◽  
Author(s):  
Yoshinori Sawae ◽  
Kanao Fukuda ◽  
Eiichi Miyakoshi ◽  
Shunichiro Doi ◽  
Hideki Watanabe ◽  
...  
Keyword(s):  
High Pressure ◽  
Stainless Steel ◽  
Wear Behavior ◽  
Hydrogen Gas ◽  
Gaseous Hydrogen ◽  
Surface Oxide Layer ◽  
Chemical Compositions ◽  
Hydrogen Environment ◽  
Sealing Materials ◽  
Pressure Hydrogen

Bearings and seals used in fuel cell vehicles and related hydrogen infrastructures are operating in pressurized gaseous hydrogen. However, there is a paucity of available data about the friction and wear behavior of materials in high pressure hydrogen gas. In this study, authors developed a pin-on-disk type apparatus enclosed in a high pressure vessel and characterized tribological behavior of polymeric sealing materials, such as polytetrafluoroethylene (PTFE) based composites, in gaseous hydrogen pressurized up to 40 MPa. As a result, the friction coefficient between graphite filled PTFE and austenitic stainless steel in 40 MPa hydrogen gas became lower compared with the friction in helium gas at the same pressure. The chemical composition of worn surfaces was analyzed by using X-ray photoelectron spectrometer (XPS) after the wear test. Results of the chemical analysis indicated that there were several differences in chemical compositions of polymer transfer film formed on the stainless disk surface between high pressure hydrogen environment and high pressure helium environment. In addition, the reduction of surface oxide layer of stainless steel was more significant in high pressure hydrogen gas. These particular effects of the pressurized hydrogen gas on the chemical condition of sliding surfaces might be responsible for the tribological characteristics in the high pressure hydrogen environment.

scholarly journals Experiments of Image Classification Using Dissimilarity Spaces Built with Siamese Networks

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1573
Author(s):  
Loris Nanni ◽  
Giovanni Minchio ◽  
Sheryl Brahnam ◽  
Gianluca Maguolo ◽  
Alessandra Lumini
Keyword(s):  
Vector Space ◽  
Image Classification ◽  
Ad Hoc ◽  
Feature Space ◽  
Medical Data ◽  
Training Data ◽  
Data Sets ◽  
Large Set ◽  
Clustering Methods ◽  
Siamese Networks

Traditionally, classifiers are trained to predict patterns within a feature space. The image classification system presented here trains classifiers to predict patterns within a vector space by combining the dissimilarity spaces generated by a large set of Siamese Neural Networks (SNNs). A set of centroids from the patterns in the training data sets is calculated with supervised k-means clustering. The centroids are used to generate the dissimilarity space via the Siamese networks. The vector space descriptors are extracted by projecting patterns onto the similarity spaces, and SVMs classify an image by its dissimilarity vector. The versatility of the proposed approach in image classification is demonstrated by evaluating the system on different types of images across two domains: two medical data sets and two animal audio data sets with vocalizations represented as images (spectrograms). Results show that the proposed system’s performance competes competitively against the best-performing methods in the literature, obtaining state-of-the-art performance on one of the medical data sets, and does so without ad-hoc optimization of the clustering methods on the tested data sets.

Effect of High Pressure Gaseous Hydrogen on the Tensile Properties of Four Types of Stainless Steels: Investigation of Materials Properties in High Pressure Gaseous Hydrogen—1

2007 ◽  
Author(s):  
Hideki Nakagawa
Keyword(s):  
High Pressure ◽  
Stainless Steel ◽  
Hydrogen Embrittlement ◽  
Storage System ◽  
Gaseous Hydrogen ◽  
Fuel Cell Vehicle ◽  
Ductility Loss ◽  
Hydrogen Storage System ◽  
Type 316L ◽  
Pressure Hydrogen

Practical application of fuel cell vehicle has started in the world, and high-pressure hydrogen tanks are currently considered to be the mainstream hydrogen storage system for commercially implemented fuel cell vehicle. Application of metallic materials to the components of high-pressure hydrogen storage system: hydrogen tanks, valves, measuring instructions and so on, have been discussed. In this work, tensile properties of four types of stainless steels were evaluated in 45MPa (6527psig) and 75MPa (10878psig) high-pressure gaseous hydrogen at a slow strain rate of 3×10−6 s−1 at ambient temperature. Type 316L (UNS S31603) stainless steel hardly showed ductility loss in gaseous hydrogen, since it had stable austenitic structure. On the other hand, Type 304 (UNS S30400) metastable austenitic stainless steel showed remarkable ductility loss in gaseous hydrogen, which was caused by the hydrogen embrittlement of strain induced martensitic phase. Likewise, Type 205 (UNS S20500) nitrogen-strengthened austenitic stainless steel showed remarkable ductility loss in gaseous hydrogen, though it had stable austenitic structure in the same manner as Type 316L. The ductility loss of Type 205 was due to the hydrogen embrittlement of austenitic phase resulting from the formation of planar dislocation array. Furthermore, Type 329J4L (UNS S31260) duplex stainless steel showed extreme ductility loss in gaseous hydrogen, which was caused by the hydrogen embrittlement of ferritic phase.

scholarly journals Proposal of Design Method Enabling Cr-Mo Steels to be Used in High-Pressure Hydrogen Gas Environment

Hyomen Kagaku ◽  
2015 ◽  
Vol 36 (11) ◽  
pp. 562-567
Author(s):  
Hisao MATSUNAGA ◽  
Junichiro YAMABE ◽  
Saburo MATSUOKA
Keyword(s):  
High Pressure ◽  
Design Method ◽  
Hydrogen Gas ◽  
Gas Environment ◽  
Pressure Hydrogen

Effect of Non-equilibrium Pulsed Ejection of Si Species into Background Gas on the Formation of Si Nanocrystallite and Nanocrystal-film

2011 ◽  
Vol 1305 ◽  
Author(s):  
Ikurou Umezu ◽  
Shunto Okubo ◽  
Akira Sugimura
Keyword(s):  
Laser Ablation ◽  
Film Growth ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Hydrogen Gas ◽  
Gas Pressure ◽  
Spatial Confinement ◽  
The Individual ◽  
Background Gas ◽  
Non Equilibrium

ABSTRACTThe Si nanocrystal-films are prepared by pulsed laser ablation of Si target in a mixture of helium and hydrogen gas. The total gas pressure and hydrogen partial gas pressure were varied to control structure of nanocrystal-film. The surface of Si nanocrystallite was hydrogenated and degree of hydrogenation increased with increasing hydrogen partial gas pressure. The aggregate structure of nanocrystal-film depended on both the total gas pressure and the hydrogen partial gas pressure. The former and the latter alter spatial confinement of Si species during deposition and the surface hydrogenation of individual nanocrystal, respectively. Spatial confinement increases probability of collision between nanocrystals in the plume. While, surface hydrogenation prevents coalescence of nanocrystals. The individual or aggregated nanocrystals formed in the plume reach the substrate and the nanocrystal-film is deposited on the substrate. The non-equilibrium growth processes during pulsed laser ablation are essential for the formation of the surface structure and the subsequent nanocrystal-film growth. Our results indicate that the structure of nanocrystal-film depends on the probabilities of collision and coalescence between nanocrystals in the plume. These probabilities can be varied by controlling the total gas pressure and the hydrogen partial gas pressure.

Crack Growth Analysis of High-Pressure Equipment for Hydrogen Storage

2013 ◽  
Author(s):  
Z. Y. Li ◽  
C. L. Zhou ◽  
Y. Z. Zhao ◽  
Z. L. Hua ◽  
L. Zhang ◽  
...  
Keyword(s):  
High Pressure ◽  
Hydrogen Storage ◽  
Crack Growth ◽  
Growth Analysis ◽  
Model Material ◽  
Hydrogen Gas ◽  
Cycle Life ◽  
Cold Worked ◽  
Type 304 ◽  
Pressure Hydrogen

Crack growth analysis (CGA) was applied to estimate the cycle life of the high-pressure hydrogen equipment constructed by the practical materials of 4340 (two heats), 4137, 4130X, A286, type 316 (solution-annealed (SA) and cold-worked (CW)), and type 304 (SA and CW) in 45, 85 and 105 MPa hydrogen and air. The wall thickness was calculated following five regulations of the High Pressure Gas Safety Institute of Japan (KHK) designated equipment rule, KHKS 0220, TSG R0002, JB4732, and ASME Sec. VIII, Div. 3. We also applied CGA for four typical model materials to discuss the effect of ultimate tensile strength (UTS), pressure and hydrogen sensitivity on the cycle life of the high-pressure hydrogen equipment. Leak before burst (LBB) was confirmed in all practical materials in hydrogen and air. The minimum KIC required for LBB of the model material with UTS of even 1500 MPa was 170 MPa·m0.5 in 105 MPa. Cycle life qualified 103 cycles for all practical materials in air. In 105 MPa hydrogen, the cycle life by KIH was much shorter than that in air for two heats of 4340 and 4137 sensitive to hydrogen gas embrittlement (HGE). The cycle life of type 304 (SA) sensitive to HGE was almost above 104 cycles in hydrogen, while the cycle life of type 316 (SA and CW) was not affected by hydrogen and that of A286 in hydrogen was near to that in air. It was discussed that the cycle life increased with decreasing pressure or UTS in hydrogen. This behavior was due to that KIH increased or fatigue crack growth (FCG) decreased with decreasing pressure or UTS. The cycle life data of the model materials under the conditions of the pressure, UTS, KIH, FCG and regulations in both hydrogen and air were proposed quantitatively for materials selection for high-pressure hydrogen storage.

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