Spain
Safe Processing Route for the Synthesis of MG Based Metallic Hydrides
Sep 2009
Publication
Metallic hydrides represent a safe way of storing hydrogen minimising explosion and flammability risks. Nowadays there are several methods for the storage of hydrogen and the more conventional techniques are high-pressure tanks for gaseous hydrogen and cryogenic vessels for liquid hydrogen. However there are two main drawbacks in the storage of gaseous and liquid hydrogen. First as a fuel hydrogen in the gaseous and liquid states is very combustible and the related law imposes strict regulations on its utilization storage and transportation. Secondly even under a high pressure hydrogen gas is not dense enough for compact storage. Moreover the gas storage at high pressure involves significant safety risks. Hydrogen storage in the metal hydrides does not have such deficiencies. Metal hydrides are safe and can be easily store and transported. For that reason it should be stressed that metallic hydrides represent a safe way of storing hydrogen minimising explosion and flammability risks. Among metallic hydrides one of the most promising hydrides in terms of absorbed hydrogen content is Mg2NiH4. However it is difficult to obtain Mg2Ni by the conventional melting method because of the large difference in vapour pressure and melting point between magnesium and nickel. This paper presents an alternative and safe method for obtaining such hydride: HCS (Hydriding Combustion Synthesis). This method presents some interesting advantages over its conventional counterpart: the process is carried out at lower reaction process which means safer process and the alloy stoichiometry is closer to the nominal (Mg2Ni) which allow better hydrogen absorption behaviour. The aim of this work is to investigate the formation mechanism of this compound and to study some parameters of the process.
Novel Safe Method Of Manufacturing Hydrogen Metallic Hydrides
Sep 2005
Publication
The present work proposes a novel safe method for obtaining metallic hydrides. The method is called SHS (Self-Propagating High temperature synthesis). A novel high pressure gas reactor governed by an electromechanical control device has been designed and built up in order to synthesise metallic hydrides. This system is provided with a control system that allows calculating the amount of gas coming into the reaction vessel at every stage of the process. The main feature of this method is that metallic hydrides can be safely synthesised using low gas reaction pressures. In order to validate the assessing system the main kinetic regularities of SHS in Ti-H2 system were studied. In addition phase analysis (by means of X ray diffraction) as well as chemical analysis have been performed.
Analysis of the Environmental Degradation Effects on the Cables of “La Arena” Bridge (Spain)
Sep 2017
Publication
After nearly 25 years of service some of the wires of the tendons of “La Arena” bridge (Spain) started to exhibit the effects of environmental degradation processes. “La Arena” is cable-stayed bridge with 6 towers and a reference span between towers of about 100 meters. After a maintenance inspection of the bridge evidences of corrosion were detected in some of the galvanized wires of the cables. A more in-deep analysis of these wires revealed that many of them exhibited loss of section due to the corrosion process. In order to clarify the causes of this degradation event and to suggest some remedial actions an experimental program was designed. This program consisted of tensile and fatigue tests on some strand samples of the bridge together with a fractographic analysis of the fracture surfaces of the wires its galvanized layer thickness and some hydrogen measurements (hydrogen embrittlement could be another effect of the environmental degradation process).Once the type and extension of the flaws in the wires was characterized a structural integrity assessment of the strands was performed with the aim of quantifying the margins until failure and establishing some maintenance recommendations.
Environmentally Assisted Cracking Behavior of S420 and X80 Steels Containing U-notches at Two Different Cathodic Polarization Levels: An Approach from the Theory of Critical Distances
May 2019
Publication
This paper analyzes using the theory of critical distances the environmentally assisted cracking behaviour of two steels (S420 and API X80) subjected to two different aggressive environments. The propagation threshold for environmentally assisted cracking (i.e. the stress intensity factor above which crack propagation initiates) in cracked and notched specimens (KIEAC and KNIEAC) has been experimentally obtained under different environmental conditions. Cathodic polarization has been employed to generate the aggressive environments at 1 and 5 mA/cm2 causing hydrogen embrittlement on the steels. The point method and the line method both belonging to the theory of critical distances have been applied to verify their capacity to predict the initiation of crack propagation. The results demonstrate the capacity of the theory of critical distances to predict the crack propagation onset under the different combinations of material and aggressive environments.
Industrial Robots Fuel Cell Based Hybrid Power-Trains: A Comparison between Different Configurations
Jun 2021
Publication
Electric vehicles are becoming more and more popular. One of the most promising possible solutions is one where a hybrid powertrain made up of a FC (Fuel Cell) and a battery is used. This type of vehicle offers great autonomy and high recharging speed which makes them ideal for many industrial applications. In this work three ways to build a hybrid power-train are presented and compared. To illustrate this the case of an industrial robot designed to move loads within a fully automated factory is used. The analysis and comparison are carried out through different objective criteria that indicate the power-train performance in different battery charge levels. The hybrid configurations are tested using real power profiles of the industrial robot. Finally simulation results show the performance of each hybrid configuration in terms of hydrogen consumption battery and FC degradation and dc bus voltage and current regulation.
Development of an Operation Strategy for Hydrogen Production Using Solar PV Energy Based on Fluid Dynamic Aspects
Apr 2017
Publication
Alkaline water electrolysis powered by renewable energy sources is one of the most promising strategies for environmentally friendly hydrogen production. However wind and solar energy sources are highly dependent on weather conditions. As a result power fluctuations affect the electrolyzer and cause several negative effects. Considering these limiting effects which reduce the water electrolysis efficiency a novel operation strategy is proposed in this study. It is based on pumping the electrolyte according to the current density supplied by a solar PV module in order to achieve the suitable fluid dynamics conditions in an electrolysis cell. To this aim a mathematical model including the influence of electrode-membrane distance temperature and electrolyte flow rate has been developed and used as optimization tool. The obtained results confirm the convenience of the selected strategy especially when the electrolyzer is powered by renewable energies.
Magnesium Based Materials for Hydrogen Based Energy Storage: Past, Present and Future
Jan 2019
Publication
Volodymyr A. Yartys,
Mykhaylo V. Lototskyy,
Etsuo Akiba,
Rene Albert,
V. E. Antonov,
Jose-Ramón Ares,
Marcello Baricco,
Natacha Bourgeois,
Craig Buckley,
José Bellosta von Colbe,
Jean-Claude Crivello,
Fermin Cuevas,
Roman V. Denys,
Martin Dornheim,
Michael Felderhoff,
David M. Grant,
Bjørn Christian Hauback,
Terry D. Humphries,
Isaac Jacob,
Petra E. de Jongh,
Jean-Marc Joubert,
Mikhail A. Kuzovnikov,
Michel Latroche,
Mark Paskevicius,
Luca Pasquini,
L. Popilevsky,
Vladimir M. Skripnyuk,
Eugene I. Rabkin,
M. Veronica Sofianos,
Alastair D. Stuart,
Gavin Walker,
Hui Wang,
Colin Webb,
Min Zhu and
Torben R. Jensen
Magnesium hydride owns the largest share of publications on solid materials for hydrogen storage. The “Magnesium group” of international experts contributing to IEA Task 32 “Hydrogen Based Energy Storage” recently published two review papers presenting the activities of the group focused on magnesium hydride based materials and on Mg based compounds for hydrogen and energy storage. This review article not only overviews the latest activities on both fundamental aspects of Mg-based hydrides and their applications but also presents a historic overview on the topic and outlines projected future developments. Particular attention is paid to the theoretical and experimental studies of Mg-H system at extreme pressures kinetics and thermodynamics of the systems based on MgH2 nanostructuring new Mg-based compounds and novel composites and catalysis in the Mg based H storage systems. Finally thermal energy storage and upscaled H storage systems accommodating MgH2 are presented.
Evaluation of Strength and Fracture Toughness of Ferritic High Strength Steels Under Hydrogen Environments
Sep 2017
Publication
The susceptibility of high strength ferritic steels to hydrogen-assisted fracture in hydrogen gas is usually evaluated by mechanical testing in high-pressure hydrogen gas or testing in air after pre-charging the specimens with hydrogen. We have used this second methodology conventionally known as internal hydrogen. Samples were pre-charged in an autoclave under 195 bar of pure hydrogen at 450ºC for 21 hours.<br/>Different chromium-molybdenum steels submitted to diverse quenching and tempering heat treatments were employed. Diverse specimens were also used: small cylindrical samples to measure hydrogen contents and the kinetics of hydrogen egression at room temperature tensile specimens notched tensile specimens with a sharp notch and also compact fracture toughness specimens. Fractographic examination in SEM was finally performed in order to know the way hydrogen modify fracture micromechanisms.<br/>The presence of hydrogen barely affects the conventional tensile properties of the steels but it clearly alters their notched tensile strength and fracture toughness. This is due to the strong effect that stress triaxiality (dependent also on the steel yield strength) has on the accumulation of hydrogen on the notch/crack front region being the displacement rate used in the test another important variable to be controlled due to its influence on hydrogen diffusion to the embrittled process zone. Moreover the modification of fracture micromechanisms was finally determined being ductile (initiation growth and coalescence of microvoids) in the absence of hydrogen and brittle and intergranular under the material conditions of maximum embrittlement.
Controller Design for Polymer Electrolyte Membrane Fuel Cell Systems for Automotive Applications
May 2021
Publication
Continuous developments in Proton Exchange Membrane Fuel Cells (PEMFC) make them a promising technology to achieve zero emissions in multiple applications including mobility. Incremental advancements in fuel cells materials and manufacture processes make them now suitable for commercialization. However the complex operation of fuel cell systems in automotive applications has some open issues yet. This work develops and compares three different controllers for PEMFC systems in automotive applications. All the controllers have a cascade control structure where a generator of setpoints sends references to the subsystems controllers with the objective to maximize operational efficiency. To develop the setpoints generators two techniques are evaluated: off-line optimization and Model Predictive Control (MPC). With the first technique the optimal setpoints are given by a map obtained off-line of the optimal steady state conditions and corresponding setpoints. With the second technique the setpoints time profiles that maximize the efficiency in an incoming time horizon are continuously computed. The proposed MPC architecture divides the fast and slow dynamics in order to reduce the computational cost. Two different MPC solutions have been implemented to deal with this fast/slow dynamics separation. After the integration of the setpoints generators with the subsystems controllers the different control systems are tested and compared using a dynamic detailed model of the automotive system in the INN-BALANCE project running under the New European Driving Cycle.
Acorn: Developing Full-chain Industrial Carbon Capture and Storage in a Resource- and Infrastructure-rich Hydrocarbon Province
Jun 2019
Publication
Juan Alcalde,
Niklas Heinemann,
Leslie Mabon,
Richard H. Worden,
Heleen de Coninck,
Hazel Robertson,
Marko Maver,
Saeed Ghanbari,
Floris Swennenhuis,
Indira Mann,
Tiana Walker,
Sam Gomersal,
Clare E. Bond,
Michael J. Allen,
Stuart Haszeldine,
Alan James,
Eric J. Mackay,
Peter A. Brownsort,
Daniel R. Faulkner and
Steve Murphy
Research to date has identified cost and lack of support from stakeholders as two key barriers to the development of a carbon dioxide capture and storage (CCS) industry that is capable of effectively mitigating climate change. This paper responds to these challenges through systematic evaluation of the research and development process for the Acorn CCS project a project designed to develop a scalable full-chain CCS project on the north-east coast of the UK. Through assessment of Acorn's publicly-available outputs we identify strategies which may help to enhance the viability of early-stage CCS projects. Initial capital costs can be minimised by infrastructure re-use particularly pipelines and by re-use of data describing the subsurface acquired during oil and gas exploration activity. Also development of the project in separate stages of activity (e.g. different phases of infrastructure re-use and investment into new infrastructure) enables cost reduction for future build-out phases. Additionally engagement of regional-level policy makers may help to build stakeholder support by situating CCS within regional decarbonisation narratives. We argue that these insights may be translated to general objectives for any CCS project sharing similar characteristics such as legacy infrastructure industrial clusters and an involved stakeholder-base that is engaged with the fossil fuel industry.
Acoustic and Psychoacoustic Levels from an Internal Combustion Engine Fueled by Hydrogen vs. Gasoline
Feb 2022
Publication
Whereas noise generated by road traffic is an important factor in urban pollution little attention has been paid to this issue in the field of hydrogen-fueled vehicles. The objective of this study is to analyze the influence of the type of fuel (gasoline or hydrogen) on the sound levels produced by a vehicle with an internal combustion engine. A Volkswagen Polo 1.4 vehicle adapted for its bi-fuel hydrogen-gasoline operation has been used. Tests were carried out with the vehicle when stationary to eliminate rolling and aerodynamic noise. Acoustics and psychoacoustics levels were measured both inside and outside the vehicle. A slight increase in the noise level has only been found outside when using hydrogen as fuel compared to gasoline. The increase is statistically significant can be quantified between 1.1 and 1.7 dBA and is mainly due to an intensification of the 500 Hz band. Loudness is also higher outside the vehicle (between 2 and 4 sones) when the fuel is hydrogen. Differences in sharpness and roughness values are lower than the just-noticeable difference (JND) values of the parameters. Higher noise levels produced by hydrogen can be attributed to its higher reactivity compared to gasoline.
Recent Advances in Pd-Based Membranes for Membrane Reactors
Jan 2017
Publication
Palladium-based membranes for hydrogen separation have been studied by several research groups during the last 40 years. Much effort has been dedicated to improving the hydrogen flux of these membranes employing different alloys supports deposition/production techniques etc. High flux and cheap membranes yet stable at different operating conditions are required for their exploitation at industrial scale. The integration of membranes in multifunctional reactors (membrane reactors) poses additional demands on the membranes as interactions at different levels between the catalyst and the membrane surface can occur. Particularly when employing the membranes in fluidized bed reactors the selective layer should be resistant to or protected against erosion. In this review we will also describe a novel kind of membranes the pore-filled type membranes prepared by Pacheco Tanaka and coworkers that represent a possible solution to integrate thin selective membranes into membrane reactors while protecting the selective layer. This work is focused on recent advances on metallic supports materials used as an intermetallic diffusion layer when metallic supports are used and the most recent advances on Pd-based composite membranes. Particular attention is paid to improvements on sulfur resistance of Pd based membranes resistance to hydrogen embrittlement and stability at high temperature.
Hydrogen in Grid Balancing: The European Market Potential for Pressurized Alkaline Electrolyzers
Jan 2022
Publication
To limit the global temperature change to no more than 2 ◦C by reducing global emissions the European Union (EU) set up a goal of a 20% improvement on energy efficiency a 20% cut of greenhouse gas emissions and a 20% share of energy from renewable sources by 2020 (10% share of renewable energy (RE) specifically in the transport sector). By 2030 the goal is a 27% improvement in energy efficiency a 40% cut of greenhouse gas emissions and a 27% share of RE. However the integration of RE in energy system faces multiple challenges. The geographical distribution of energy supply changes significantly the availability of the primary energy source (wind solar water) and is the determining factor rather than where the consumers are. This leads to an increasing demand to match supply and demand for power. Especially intermittent RE like wind and solar power face the issue of energy production unrelated to demand (issue of excess energy production beyond demand and/or grid capacity) and forecast errors leading to an increasing demand for grid services like balancing power. Megawatt electrolyzer units (beyond 3 MW) can provide a technical solution to convert large amounts of excess electricity into hydrogen for industrial applications substitute for natural gas or the decarbonization of the mobility sector. The demonstration of successful MW electrolyzer operation providing grid services under dynamic conditions as request by the grid can broaden the opportunities of new business models that demonstrate the profitability of an electrolyzer in these market conditions. The aim of this work is the demonstration of a technical solution utilizing Pressurized Alkaline Electrolyzer (PAE) technology for providing grid balancing services and harvesting Renewable Energy Sources (RES) under realistic circumstances. In order to identify any differences between local market and grid requirements the work focused on a demonstration site located in Austria deemed as a viable business case for the operation of a largescale electrolyzer. The site is adapted to specific local conditions commonly found throughout Europe. To achieve this this study uses a market-based solution that aims at providing value-adding services and cash inflows stemming from the grid balancing services it provides. Moreover the work assesses the viability of various business cases by analyzing (qualitatively and quantitatively) additional business models (in terms of business opportunities/energy source potential grid service provision and hydrogen demand) and analyzing the value and size of the markets developing recommendations for relevant stakeholder to decrease market barriers.
Gaseous Fueling of an Adapted Commercial Automotive Spark-ignition Engine: Simplified Thermodynamic Modeling and Experimental Study Running on Hydrogen, Methane, Carbon Monoxide and their Mixtures
Dec 2022
Publication
In the present work methane carbon monoxide hydrogen and the binary mixtures 20 % CH4–80 % H2 80 % CH4–20 % H2 25 % CO–75 % H2 (by volume) were considered as fuels of a naturally aspirated port-fuel injection four-cylinder Volkswagen 1.4 L spark-ignition (SI) engine. The interest in these fuels lies in the fact that they can be obtained from renewable resources such as the fermentation or gasification of residual biomasses as well as the electrolysis of water with electricity of renewable origin in the case of hydrogen. In addition they can be used upon relatively easy modifications of the engines including the retrofitting of existing internal combustion engines. It has been found that the engine gives similar performance regardless the gaseous fuel nature if the air–fuel equivalence ratio (λ) is the same. Maximum brake torque and mean effective pressure values within 45–89 N⋅m and 4.0–8.0 bar respectively have been obtained at values of λ between 1 and 2 at full load engine speed of 2000 rpm and optimum spark-advance. In contrast the nature of the gaseous fuel had great influence upon the range of λ values at which a fuel (either pure or blend) could be used. Methane and methane-rich mixtures with hydrogen or carbon monoxide allowed operating the engine at close to stoichiometric conditions (i.e. 1 < λ < 1.5) yielding the highest brake torque and mean effective pressure values. On the contrary hydrogen and hydrogen-rich mixtures with methane or carbon monoxide could be employed only in the very fuel-lean region (i.e. 1.5 < λ < 2). The behavior of carbon monoxide was intermediate between that of methane and hydrogen. The present study extends and complements previous works in which the aforementioned fuels were compared only under stoichiometric conditions in air (λ = 1). In addition a simple zero-dimensional thermodynamic combustion model has been developed that allows describing qualitatively the trends set by the several fuels. Although the model is useful to understand the influence of the fuels properties on the engine performance its predictive capability is limited by the simplifications made.
Experimental Study of Biogas-Hydrogen Mixtures Combustion in Conventional Natural Gas Systems
Jul 2021
Publication
Biogas is a renewable gas with low heat energy which makes it extremely difficult to use as fuel in conventional natural gas equipment. Nonetheless the use of hydrogen as a biogas additive has proven to have a beneficial effect on flame stability and combustion behavior. This study evaluates the biogas–hydrogen combustion in a conventional natural gas burner able to work up to 100 kW. Tests were performed for three different compositions of biogas: BG70 (30% CO2) BG60 (40% CO2) and BG50 (50% CO2). To achieve better flame stability each biogas was enriched with hydrogen from 5% to 25%. The difficulty of burning biogas in conventional systems was proven as the burner does not ignite when the biogas composition contains more than 40% of CO2. The best improvements were obtained at 5% hydrogen composition since the exhaust gas temperature and thus the enthalpy rises by 80% for BG70 and 65% for BG60. The stability map reveals that pure biogas combustion is unstable in BG70 and BG60; when the CO2 content is 50% ignition is inhibited. The properties change slightly when the hydrogen concentrations are more than 20% in the fuel gas and do not necessarily improve.
Thermodynamic Analysis of a Regenerative Brayton Cycle Using H2, CH4 and H2/CH4 Blends as Fuel
Feb 2022
Publication
Considering a simple regenerative Brayton cycle the impact of using different fuel blends containing a variable volumetric percentage of hydrogen in methane was analysed. Due to the potential of hydrogen combustion in gas turbines to reduce the overall CO2 emissions and the dependency on natural gas further research is needed to understand the impact on the overall thermodynamic cycle. For that purpose a qualitative thermodynamic analysis was carried out to assess the exergetic and energetic efficiencies of the cycle as well as the irreversibilities associated to a subsystem. A single step reaction was considered in the hypothesis of complete combustion of a generic H2/CH4 mixture where the volumetric H2 percentage was represented by fH2 which was varied from 0 to 1 defining the amount of hydrogen in the fuel mixture. Energy and entropy balances were solved through the Engineering Equation Solver (EES) code. Results showed that global exergetic and energetic efficiencies increased by 5% and 2% respectively varying fH2 from 0 to 1. Higher hydrogen percentages resulted in lower exergy destruction in the chamber despite the higher air-excess levels. It was also observed that higher values of fH2 led to lower fuel mass flow rates in the chamber showing that hydrogen can still be competitive even though its cost per unit mass is twice that of natural gas.
An Autonomous Device for Solar Hydrogen Production from Sea Water
Feb 2022
Publication
Hydrogen production from water electrolysis is one of the most promising approaches for the production of green H2 a fundamental asset for the decarbonization of the energy cycle and industrial processes. Seawater is the most abundant water source on Earth and it should be the feedstock for these new technologies. However commercial electrolyzers still need ultrapure water. The debate over the advantages and disadvantages of direct sea water electrolysis when compared with the implementation of a distillation/purification process before the electrolysis stage is building in the relevant research. However this debate will remain open for some time essentially because there are no seawater electrolyser technologies with which to compare the modular approach. In this study we attempted to build and validate an autonomous sea water electrolyzer able to produce high-purity green hydrogen (>90%) from seawater. We were able to solve most of the problems that natural seawater electrolyses imposes (high corrosion impurities etc.) with decisions based on simplicity and sustainability and those issues that are yet to be overcome were rationally discussed in view of future electrolyzer designs. Even though the performance we achieved may still be far from industrial standards our results demonstrate that direct seawater electrolysis with a solar-to-hydrogen efficiency of ≈7% can be achieved with common low-cost materials and affordable fabrication methods.
Opportunities and Barriers of Hydrogen–Electric Hybrid Powertrain Vans: A Systematic Literature Review
Oct 2020
Publication
The environmental impact of the road transport sector together with urban freight transport growth has a notable repercussions in global warming health and economy. The need to reduce emissions caused by fossil fuel dependence and to foster the use of renewable energy sources has driven the development of zero-emissions powertrains. These clean transportation technologies are not only necessary to move people but to transport the increasing demand for goods and services that is currently taking place in the larger cities. Full electric battery-powered vans seem to be the best-placed solution to the problem. However despite the progress in driving range and recharge options those and other market barriers remain unsolved and the current market share of battery electric vehicles (BEVs) is not significant. Based on the development of hydrogen fuel cell stacks this work explains an emerging powertrain architecture concept for N1 class type vans that combines a battery-electric configuration with a fuel cell stack powered by hydrogen that works as a range extender (FC-EREV). A literature review is conducted with the aim to shed light on the possibilities of this hybrid light-duty commercial van for metropolitan delivery tasks providing insights into the key factors and issues for sizing the powertrain components and fuel management strategies to meet metropolitan freight fleet needs.
Hydrogen Effects on Progressively Cold-Drawn Pearlitic Steels: Between Donatello and Michelangelo
Sep 2017
Publication
This paper reviews previous research by the author in the field of hydrogen effects on progressively cold-drawn pearlitic steels in terms of hydrogen degradation (HD) hydrogen embrittlement (HE) or at the micro-level hydrogen-assisted micro-damage (HAMD) thus affecting their microstructural integrity and compromising the (macro-)structural integrity of civil engineering structures such as prestressed concrete bridges. It is seen that hydrogen effects in pearlitic microstructure (either oriented or not) are produced at the finest micro-level by plastic tearing in the form in general of hydrogen damage topography (HDT) with different appearances depending of the cold drawing degree evolving from the so-called tearing topography surface (TTS) in hot-rolled (not cold-drawn at all) or slightly cold-drawn pearlitic steels to a sort of enlarged and oriented TTS (EOTTS) in heavily drawn steels (the pronounced enlargement and marked orientation being along the wire axis or cold drawing direction). Whereas the pure TTS mode (null or low degree of cold drawing) resembles the Michelangello stone sculpture texture (MSST) the EOTTS mode does the same in relation to the Donatello wooden sculpture texture (DWST).
Hydrogen Assisted Macrodelamination in Gas Lateral Pipe
Jul 2016
Publication
Hydrogen assisted macrodelamination in the pipe elbows of 40-year exploited lateral pipelines located behind the compressor station was studied. The crack on the external surface of the pipe elbow was revealed. Macrodelamination was occurred in the steel being influenced by the joined action of working loads and hydrogen absorbed by metal during long-term operation. The causes of the material degradation were investigated by non-destructive testing using ultrasound thickness meter observing microstructure hydrostatic pressure testing and mechanical properties testing of pipe steel.<br/>Intensive degradation of steel primarily essential reduction of plasticity was revealed. The degradation degree of the pipe elbow steel was higher than of the straight pipe steel regardless of a section was tensioned or compressed. Basing on the tensile tests carried out on cylindrical smooth and notched specimens from the pipe elbow steel it was established that the plasticity of the damaged steel could be measured correctly only on the specimens with a circular notch due to concentration of deformation in the cross section location only. The limitations in using elongation and reduction in area for characterisation of plasticity of the pipe steel with extensive delamination were defined. The diagnostic features of macrodelamination namely an abnormal thickness meter readings and a sharp decrease in hardness and plasticity of the pipe elbow steel were established.
No more items...