Determination Of Hydrogen Content Research Articles

Probing hydrogen content in steel using the thermoelectric effect

The issue of hydrogenation of steel is a serious technological problem. Due to its small atomic radius, hydrogen is difficult to analyze quantitatively and qualitatively. Non-destructive estimation of hydrogen content would significantly improve the quality control process. In this work, we attempt to develop a new methodology for the determination of hydrogen content in 4340 steel using the thermoelectric effect. For this purpose, we investigated the mechanisms of hydrogenation, structural and microstructural changes caused by hydrogenation, and performed theoretical calculations of the influence of hydrogen on the electronic structure of steel. Measurements of the Seebeck coefficient were performed using the specially developed μm-resolution scanning thermoelectric microscope (SThM). The KKR-CPA calculations show that hydrogen located at T-voids strongly modifies electronic properties and influences the Seebeck coefficient of the material. Ultraviolet photoelectron spectroscopy (UPS) proves that hydrogenated samples exhibit the valence band onset shift towards higher binding energies concerning the non-hydrogenated materials. Theoretical and experimental studies of the Seebeck coefficient dependence on the total hydrogen content confirm a measurable decrease in the Seebeck coefficient (18.5 µV/K for 0.136 ppm and 13.5 µV/K for 1.03 ppm). Plotted calibration curves for 4340 steel were used for preliminary kinetic studies of the spontaneous dehydrogenation in this material. This work demonstrates that the thermoelectric effect can be used as the basis of a new fast and non-destructive analytical method for the determination of the hydrogen content in 4340 steel.

In situ measurement of hydrogen concentration in steel using laser-induced breakdown spectroscopy (LIBS)

AbstractThe ISO 3690 standard “Determination of hydrogen content in arc weld metal” requires a thermal activation of the diffusible hydrogen in a piece of weld metal for the subsequent ex situ concentration measurement by carrier gas hot extraction CGHE or thermal desorption spectroscopy (TCD). Laser-induced breakdown spectroscopy (LIBS) offers a time and spatially resolved, almost non-destructive, in situ measurement of hydrogen at surfaces without sample preparation. We measured hydrogen in steels, which were charged either electrochemically or by high-pressure hydrogen gas, and compared the results. Further, the feasibility of quantitative hydrogen line scan measurements with LIBS was demonstrated by measuring hydrogen at water jet cut surfaces. The hydrogen concentrations measured with the help of LIBS were compared with CGHE measurements. It was observed that hydrogen can be reliably measured with LIBS for concentrations larger than 2 wt.-ppm. The maximum hydrogen concentration achieved using electrochemical charging was 85.1 ppm. The results show that LIBS is a promising technique for time- and spatially resolved measurements of hydrogen in steels.

Determination of Hydrogen Content in Getter Material from Parabolic Trough Receivers

In this study, a procedure for analyzing the hydrogen content of used getter material is described based on mass spectrometry coupled to thermal gravimetry. It is shown that hydrogen masses per getter mass in the range of 2 – 15 mg/g can be quantified. At least three differently strong hydrogen binding situations are found with the thermal desorption program applied so far. Up to 450 °C only traces of hydrogen can be desorbed from the getter material with the applied method and up to 99% is released on heating up to 800 °C.

Hydrogen content in divertor baffle tiles in Wendelstein 7-X

Abstract Plasma–wall interactions play a crucial role for the performance of fusion devices and the lifetime of plasma-facing components. In this work the results of some plasma–wall interaction processes, namely the erosion/deposition pattern and the fuel content of divertor baffle tiles exposed in Wendelstein 7-X in the initial phase of island divertor, are presented. Net-deposition of carbon with co-deposited oxygen and hydrogen is determined on the graphite tiles after about 1 hour of plasma operation in hydrogen and helium in operation phase OP 1.2a. C is predominately a result of net-erosion of the graphite target plates and oxygen is the strongest intrinsic impurity in Wendelstein 7-X in OP 1.2a. The hydrogen content distribution on a set of tiles exposed in equivalent positions in three of the five modules of the stellarator was quantified for the first time. Ex-situ performed laser-induced breakdown spectroscopy measurements show the depth-resolved fuel content in deposited layers as well as implantation and diffusion in the base material. Complementary, gas analysis after laser-induced ablation offers quantitative hydrogen content determination in the deposited layers up to 1018 hydrogen atoms/cm 2 that is non-uniformly distributed over the 95 mm × 125 mm sized tiles. The results show a toroidal asymmetry with 60% more hydrogen in the stellarator module 2 with respect to module 1 as well as a slight top-down asymmetry for the baffle tiles in upper and lower half modules. A clear dependence of the hydrogen content on the surface temperature during plasma exposition in stellarator discharges in standard magnetic divertor configuration with edge transformation 5/5 was not observed.

Investigation of the influence of the parameters of the laser welding technological process on the chemical composition, structural-phase state and physicochemical properties of the material of the weld, heat-affected zone, pipe body and product

The aim of this work is to study the welds of titanium grade VT1-0. In this work, we study the chemical composition, microstructure of the weld, the heat-affected zone and the body of the material, mechanical tensile tests, microhardness measurements and determination of hydrogen content

Analysis of Samples Cleaning Methods Prior to Hydrogen Content Determination in Steel

There are multiple references to sample cleaning methods prior to hydrogen content determination, or hydrogen spectroscopy analysis, but there is still no unified criteria; different authors use their own “know-how” to perform this task. The aim of this paper is to solve, or at least clarify, this issue. In this work, the most commonly used sample cleaning methods are compared. Then, five different methodologies are applied on certified hydrogen content calibration pins and on high strength steel concrete-prestressing strands and the three main situations regarding hydrogen content in the microstructural net (non-charged, charged, and charged and uncharged) are studied. It was concluded that the HCl solution C-3.5 cleaning method recommended by ASTM G1 introduces large amounts of hydrogen in the samples; but can be useful for eliminating superficial oxides if necessary. The rest of the methods had similar results; but the more complete ones that involve ultrasounds and last longer than 8 min are not appropriated when important diffusion may occur on the samples during their application. Simple methods that involve acetone or trichloroethylene and last around 1 min are preferable for almost all situations as these are faster, easier, and cheaper. As a final recommendation, as trichloroethylene is toxic, the simple acetone method is, in general, the most convenient one for regular hydrogen content analysis.

Peculiarities of Application of the Gas Extraction Method for Determination of Hydrogen Content in Samples of Irradiated Zirconium Materials

Results of multiyear research of zirconium materials from nuclear reactors show that the hydrogen content measured by a high-temperature extraction method does not always correlate with the number and size of zirconium hydrides measured by metallography. Additional examinations found that hydrogen is contained not only in the metal but also in the oxide film of samples under examination. This means that the level of hydrogenation of zirconium materials under irradiation should be estimated by the hydrogen content in metal only to allow for a correct comparison of the results of gas analysis and metallographic investigations. In this connection, the hydrogen content was measured separately in the metal and in the oxide film. A device to mechanically remove sediments and oxide film from samples was developed. However, when removing the oxide mechanically, a top layer of metal is also removed, as a rule, which leads to an uncontrolled increase in the measurement error because of a nonuniform distribution of hydrides in the metal. The assessment of the contribution of oxide hydrogen using a curve “total hydrogen content vs. oxide film thickness” showed no distinct dependence. Moreover, it was stated that the results of the total hydrogen content measurements by the high-temperature extraction method can be affected by the elementary composition of sediments and oxide films on the surfaces of spent items. The performed research resulted in the development of a technique to measure the hydrogen mass fraction by high-temperature extraction in an inert gas flow separately in the metal and oxide film without any preliminary mechanical removal of the oxide. This will allow examining the dependence between the hydrogen content in the oxide film and its thickness, as well as estimating a possible correlation between the hydrogen mass fraction in the metal and the quantitative characteristics of hydrides measured by a metallographic image.

The Determination of the Hydrogen Content in the Aluminium Alloys Casted by Tekcast Method

This research publication presents the method of centrifugal casting TEKCAST for the selected aluminium alloy AlSi10Mn STN 42 4383. The aim is the research and determination of hydrogen content depending on a rotation rate of mold during false centrifugal casting. Then it is an observation of the changes in mechanical and structural properties depending on the changes caused by increased content of hydrogen.

Middle distillates hydrogen content via GC×GC-FID

Liquid transportation fuels in the middle distillate range contain thousands of hydrocarbons making the predictions and calculations of properties from composition a challenging process. We present a new approach of hydrogen content determination by comprehensive two-dimensional gas chromatography with flame ionization detector (GC×GC-FID) using a weighted average method. GC×GC-FID hydrogen determination precision was excellent (0.005 wt% repeatability). The method accuracy was evaluated by high-resolution nuclear magnetic resonance (NMR) technique, which is non-biased, measures the H signal directly and was independently validated by controls in the current study. The hydrogen content (in the range of 12.72–15.54 wt%) in 28 fuel samples were determined using GC×GC-FID. Results were within ± 2% of those obtained via NMR. Owing to the fact that NMR is accepted as an accurate technique for hydrogen content determination, the GC×GC method proposed in this study can be considered precise and accurate.

Techniques for investigation of hydrogen embrittlement of advanced high strength steels

AbstractProduction volumes of advanced high strength steels (AHSS) are growing rapidly due to material and energy savings they provide in a number of application areas. In order to use their potential fully, it is necessary to minimize any danger of unexpected failures caused by hydrogen embrittlement. It is possible only if deeper understanding of underlying mechanisms is obtained through further research. Besides description of main grades of AHSS and mechanisms of HE, this paper reviews available tools for determination of hydrogen content and susceptibility to HE focusing on atmospheric conditions. Techniques such as slow strain rate testing, constant load testing, electrochemical permeation technique, scanning Kelvin probe and scanning Kelvin probe force microscopy have already been used to study the effect of hydrogen entered under atmospheric exposure conditions. Nanoindentation, hydrogen microprint technique, thermal desorption spectroscopy, Ag decoration or secondary ion mass spectrometry can be also conducted after atmospheric exposure.

Особенности применения метода газовой экстракции для определения содержания водорода в образцах из облученных циркониевых материалов

Особенности применения метода газовой экстракции для определения содержания водорода в образцах из облученных циркониевых материалов

Corrosion behavior of hydrogen charged super duplex stainless steel welded joints

The electrochemical behavior of the weld metal, heat‐affected zone (HAZ), and base material of super duplex stainless steel (SDSS) welded joints, made with the application of flux‐cored arc welding (FCAW) and submerged arc welding (SAW), were investigated with the use of metallographic examinations (optical microscopy and scanning electron microscopy), potentiodynamic polarization measurements and total hydrogen content determination in the initial state and after hydrogen charging. The obtained results revealed that the effect of hydrogen depended on the microstructure and type of the region of a welded joint. The highest amount of hydrogen penetrated the welded joint charged at 1 mA cm−2. It was observed in case of the FCAW‐welded joint, made with lower heat input. The electrochemical measurements showed that the base material was the most corrosion resistant part of the welded joint while the hydrogen charging strongly changed pitting and general corrosion susceptibility of HAZ and weld metal of both welded joints.

Determination of Hydrogen Content and Dehydrogenation in Molten Aluminum by Concentration Cell Method

The CaZr0.9In0.1O3-α proton conductor was prepared by solid reaction method with high purity and small particle size. Two types hydrogen sensors and pump based on the proton conductor were fabricated for monitoring the hydrogen content and dehydrogenation in molten aluminum at 760 . The °C electromotive force (EMF) and time of hydrogen sensor with the inverted-U electrolyte tube followed a smooth curve in which the EMF tended to be stable after about 13 min whose sensing performance was superior to that with the upright-U electrolyte tube. The sensor EMF increased with the pressure or flow rate of referent gas according to Nernst equation. The equilibrium time of EMF increased and the transferring resistance between the Pt electrode and proton conductor’s transfer resistance decreased with the flow rate of reference gas. Therefore, inverted-U type tube and flow rate value of reference gas were very important to acquire the sensitive and accurate hydrogen content values in molten aluminum. In addition, hydrogen pump based on concentration cell had feasibility and actual using value for the dehydrogenation of molten aluminum.

Failure analysis of vessel propeller bolts under fastening stress and cathode protection environment

This paper describes the failure analysis of propeller blade fastening bolts made from martensitic stainless steel 0Cr16Ni5Mo, which was ruptured under service of cathode protection for 5years. The general crack pattern of the bolts, fractographic features, hydrogen content determination and slow tensile test results are all exhibiting the characteristics of hydrogen embrittlement. Accordingly, hydrogen diffusion driven by hydrogen concentration gradient and stress concentration was identified by experiment and finite element analysis (FEA). The morphology of the crack was intergranular of initiation from bolt cap root surface, and quasi-cleavage of propagation. The hydrogen distribution indicated that the hydrogen concentration in the bolt was in gradient distribution, and the region farther away from the sea water contains less hydrogen content. This revealed that hydrogen entered the bolt top surface through sea water under cathodic protection, and diffused from top to cap. The hydrogen content of the cap where crack initiated was 7.0ppm, which was much higher than that in bolt shaft with normal content of 1.1ppm. Results of low tensile test together with fractographic observation showed that the brittleness of the bolt was enhanced by the effect of hydrogen. Stress distribution calculated by FEA analysis indicated that the maximal stress of the bolt was about 1016MPa, located at cap root surface which was consistent with crack initiation sites. The stress drove hydrogen to accumulate at root surface until cracking occurred. In a sum, the failure was attributed to the hydrogen diffusion, local high stress, and the martensitic microstructure susceptible to hydrogen embrittlement. Remedial measures such as avoiding over protection potential, that increase tempering temperature were suggested. Methods to optimize stress distribution of the bolt were also suggested based on FEA calculation.

Elastic recoil cross section determination of 1H by 4He ions at 30° and energy range of 1.6–6.0 MeV

In this paper, the differential cross-section for forward recoiling 1H with 4He ions has been determined in the energy range of 1.6–6.0MeV at a laboratory angle of 30°. A film of ∼54nm TiHx on the Si substrate with an overlayer of ∼7nm Ta on the TiHx foil was used as the target, and hydrogen loss of the target due to ion bombardment can be fully ignored (<0.1%) through the whole measurement. A method of relative determination for the cross-section measurement was employed to be free from absolute determination of hydrogen content in the target as well as absolute measurements of beam dose and solid angles of the detectors. The uncertainty of the determination is less than 5.2%.

Определение содержания водорода во фторидно-оксидных флюсах

Определение содержания водорода во фторидно-оксидных флюсах

Impact of Sample Preparation on Determination of Hydrogen Content in TC4 Titanium Alloys

Impact of sample preparation on determination of hydrogen content in TC4 titanium alloys is studied through the experimental test method which was developed according to ASTM E 1447-2009. The simulation of the heating process in sample preparation process verifies the slight warming (60°C ~ 80 °C) will affect the test result of hydrogen content in TC4 titanium alloys. The heating process makes the result be lower than the actual content.

Reverse ageing in hot-rolled high-carbon steel wire rod

Effects of ageing time on area reduction of hot-rolled high-carbon steel wire rods were studied. Tensile testing and X-ray study of as-rolled wire rods were carried out. Gleeble simulation and hydrogen content determination were also conducted. The results show that the reduction of area increases with ageing time at room temperature and the UTS remain unchanged which are contrary to normal ageing or strain ageing. In normal ageing, the ductility drops and the yield strength increases. In this study, the Gleeble simulation and X-ray data support that the transformation from pearlite to austenite is normal and there is no evidence of retained austenite or martensitic transformation in the steel. The hydrogen content drops as the time passes. The drop is rapid in first few days and this drop increases the ductility in rolled high-carbon wire rod. Hydrogen reduces the cohesive strength and the pressure generated due to transformation of atomic hydrogen-to-molecular state combines with tensile stress and causes cleavage or mixed type of fracture.

Improvement of the determination of hydrogen content in a multicomponent sample by D–T generator

If a D–T generator is used as a neutron source to simultaneously measure the content of carbon, hydrogen and oxygen in a multicomponent sample by NIPGA (Neutron Induced Prompt Gamma-ray Analysis), the 14 MeV neutron flux can be regarded as a constant value. The relationship between the production of the hydrogen characteristic gamma-rays and its content is nonlinear. In this paper, we use MCNP (Monte Carlo N-Particle Transport code) to simulate the relationship and analyze it. In practical measurement of the characteristic gamma-ray, it's impossible to get the net count. Therefore, we use the experiment to obtain the relationship between the hydrogen content and the total count of its characteristic gamma-rays. If we use the relationship combined with the simulation result to calculate the hydrogen content, the metrical precision can be much increased. The deviation of hydrogen content between NIPGA and chemical analysis is less than 0.25%, which meets the requirement of coal industry.

Synthesis of hydrogen tungsten bronzes H xWO 3 by reactive mechanical milling of hexagonal WO 3

Recently, we have reported the formation of hydrogen tungsten bronzes by reactive mechanical milling monoclinic tungsten (VI) oxide under hydrogen atmosphere. In this work we report the milling of hexagonal WO 3 under H 2 atmosphere. Our main results are the structural transformation of the hexagonal oxide to the high temperature polymorph of WO 3 with orthorhombic structure, and the formation of different hydrogen tungsten bronzes at distinct milling times. The bronzes seem to be formed from the orthorhombic oxide, and compared with the bronzes obtained by milling monoclinic WO 3 are rather unstable after short exposure to air. The materials are characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and total hydrogen content determination.