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The compatibility problems become main concern in the utilization of biodiesel especially regarding to degradation and corrosion. The present study is conducted to describe the corrosion behaviour that occurs in steel tanks after contact with palm-based biodiesel for a period of 7 months. The storage tank used is respectively made of galvanised steel (GS), carbon steel (CS) and stainless steel (SS). It is performed in vertical cylinders with a floating-roof model. In every 30 days of storage time, the profile changes in the wall, roof and base surface of each tank were observed. The oil fuel properties were monitored in the parameter of viscosity, acid numbers, water content and oil colour. The topographic profiles on the surface of the walls and bottom of each tank wetted by biodiesel were examined over three zones inside the tanks using an endoscope imager. The main results of this study indicate that the tank steel with different protective layers exhibits different types of corrosion. The corrosion was localized in SS tanks but generalized in GS and CS tanks. The oil contamination in SS tanks was relatively lower than that in CS and GS tanks. The type of corrosion performed differently in different zones on the inside of the tank. The potential for leaks is greater at the base than on the walls and roof of the storage tank.

The role of biofilm in the Microbiologically Influenced Corrosion (MIC) of carbon steel by Sulfate Reducing Bacteria (SRB) in oil and gas exploitation, and geothermal installations is investigated. Simulated biofilm made of calcium alginate, abiotic sulfide (to mimic SRB metabolic end product H2S), CO2 (to mimic CO2 from SRB dissimilatory sulfate reduction) and simulated brine (3.0 wt% NaCl) are used to simulate the SRB environment. For reference experiments, distilled water is used instead of simulated brine. The electrochemical results show that the simulated biofilm in the reference at 120 min exposure time and in brine experiments neither inhibits nor accelerates corrosion. These results are strongly supported by corrosion kinetic adsorption parameters, statistical T-test, ICP-OES, pH, SEM-EDS and XRD. The results contradict with the existing literature on the role of biofilm and this is likely due to the presence of both H2S and CO2 as simulated SRB metabolites. Despite of this discrepancy, the obtained corrosion rates (0.25 to 1.6 mm/year) in the simulated SRB environment are comparable to published corrosion rates obtained in SRB experiments (0.20 to 1.2 mm/year). The results highlight the novelty of this research and have a direct impact on the role of other microbial metabolites on the corrosion of carbon steel.

To explore the evolution mechanism of multistage machining processes and torsional fatigue behaviour based on strain energy for the first time and provide process optimization of axis parts of low-alloy medium-carbon steel for service performance, four multistage machining processes were applied to the 45CrNiMoVA steel, including the rough turning process (RT), RT + the finish turning process (FRT), FRT+ the grinding process (GFRT) and RT+ the finish turning process on dry cutting condition (FRT0). The result showed that the FRT process’s average low-cycle torsional fatigue life increased by 50% when it evolved from the RT process. The lower surface roughness of Ra 1.3 μm caused the total strain energy to increase by 163.8 Pa mm/mm instead of the unchanged strain energy density, and the crack feature evolved from some specific bulges to flat shear plane characteristics. When the GFRT process evolved from the FRT process, its average fatigue life increased by 1.45 times, compared with the RT process. Plastic strain amplitude decreased by 21%, and the strain energy density decreased by 4% due to more considerable compressive residual stress (-249 MPa). Plastic deformation layer depth had a consistent tendency with surface roughness. In this paper, surface integrity evolutions on cyclic characteristics and fatigue behaviour have also been explained. A fatigue life prediction model based on the energy method for machined surface integrity is proposed.

Etching of steel items in sulfuric acid solution is used in various human activities (oil and gas industry, metal production, utilities, transport, etc.). This operation is associated with significant material costs due to corrosion losses of the metal. It has been found that an efficient way to prevent corrosion of steel in sulfuric acid solution involves the formation of thin protective films consisting of corrosion inhibitor molecules of triazole class on its surface. It has been shown that the protection of steels with a 3-substituted 1,2,4-triazole (3ST) in H2SO4 solution is accompanied by the formation of a polymolecular layer up to 4 nm thick. The 3ST layer immediately adjacent to the steel surface is chemisorbed on it. The efficiency of this compound as an inhibitor of corrosion and hydrogen absorption by steel is determined by its ability to form a protective organic layer, as experimentally confirmed by XPS and AFM data. The kinetic constants of the main stages of hydrogen evolution and permeation into steel in the H2SO4 solution were determined. A significant decrease in both the reaction rate of cathodic hydrogen evolution and the rate of hydrogen permeation into steel by the triazole in question was noted. It has been shown that the preservation of the metal plasticity in the acid medium containing the triazole under study is due to a decrease in the hydrogen concentration in the metal bulk.

Acid mine drainage (AMD), resulting from mining activities, poses a significant environmental concern. It adversely affects metallic materials, particularly carbon steel composites used in mining machinery and structures. Highly acidic and oxidizing compounds like sulfuric acid and ferric ions cause corrosion, iron oxide formation, and hydrogen gas release, which degrade carbon steel. AMD also alters the solvent’s properties, dissolving heavy metals and contaminants, and intensifying the environmental impact of mining. A 30-week experiment immersed metal plates in AMD to study its effects. Weekly observations of the plates and solvent were made. The plate measurements and physicochemical data were analyzed using graphical–statistical analysis and fuzzy logic techniques to assess the data quality and identify errors. The results reveal consistent findings with prior studies, such as material degradation with weight loss and alterations in acid drainage media, including increased pH and total dissolved solids (TDS). These changes in the solvent characteristics stem from the dissolution of metal ions from corroded surfaces, reacting with the acid solution. Overall, this study discusses the effects of AMD (acid mine drainage) on metallic materials and emphasizes the significance of monitoring and reducing the environmental consequences of mining activities., This research was funded by the Ministry of Science and Innovation (Spain), grant number PID2021-123130OB-I00.

This paper investigated carbon steel corrosion in an enclosed environment, where one set of steel was immersed in 3.5 wt.% NaCl solution and another exposed to humid (condensation) conditions. The study employed electrochemical noise and electrochemical impedance spectroscopy techniques to monitor real time corrosion behaviour. The samples were evaluated with surface characterisation techniques including optical light microscope, scanning electron microscope with energy dispersive X-ray spectroscopy, and Raman spectroscopy. The results showed that carbon steel immersed in the liquid phase at a constant temperature exhibited the highest weight loss. However, the carbon steel exposed to water condensation (gas phase) at 80 °C manifested extensive localised corrosion. EN results agreed with the microscopy findings.

Corrosion is a key long-term degradation process for metallic components in nuclear industry infrastructure. Accurately predicting the corrosion rate of a component in its service environment is considered a grand challenge in the corrosion community. Corrosion is a multi-step electrochemical process, with elementary steps involving mass transfer across more than one stage. Due to the multi-step, multi-phase nature of corrosion systems, predicting corrosion behaviour over time is complex. Existing corrosion models can describe electron transfer and mass transport steps independently, under narrow sets of conditions or over a specified duration but cannot account for the changes that occur over time due to the coupling of elementary steps. Developing a detailed understanding of the interfacial chemical dynamics from the earliest stages of corrosion is critical to developing a rate model that adequately describes the evolution of corrosion systems over a wider range of environmental conditions and durations. This thesis identifies and describes the initial interfacial chemical dynamics in corrosion systems and presents a corrosion model framework and mechanism that describe the initial corrosion behaviour as a function of solution redox and transport parameters. The rate-controlling elementary steps in the metal oxidation and oxidant reduction half-reactions are identified and decoupled. Electrochemical polarization tests on carbon steel are used to identify the independent effects of the purging gas (e.g., Argon or 21% O2), solution pH (pH 6.0 – 8.0), solution ionic strength, and concentration of radiolysis products (e.g., H2O2) on the rates of each elementary step. Overpotential and pH-dependent rate equations for metal oxidation and oxidant reduction half-reactions are developed. The proposed mechanism for the initial stage corrosion is shown to be well supported by the experimental observations and its extension to other metals (e.g., Co, Ni) is discussed. This research provides a mechanistic understanding of corrosion at the metal-solution interface in its early stages and offers an approach to describe the evolution of corrosion in various solution conditions. A better understanding of fundamental interfacial processes will enhance the general understanding of corrosion and improve the process of developing predictive models for a wide range of interfacial systems.

Novel imine-tethering cationic surfactants, namely (E)-3-((2-chlorobenzylidene)amino)-N-(2-(decyloxy)-2-oxoethyl)-N,N-dimethylpropan-1-aminium chloride (ICS-10) and (E)-3-((2-chlorobenzylidene)amino)-N,N-dimethyl-N-(2-oxo-2-(tetradecyloxy)ethyl)propan-1-aminium chloride (ICS-14), were synthesized, and the chemical structures were elucidated by various spectroscopic approaches. The surface properties of the target-prepared imine-tethering cationic surfactants were investigated. The effects of both synthesized imine surfactants on carbon steel corrosion in a 1.0 M HCl solution were investigated by weight loss (WL), potentiodynamic polarization (PDP), and scanning electron microscopy (SEM) methods. The outcomes show that the inhibition effectiveness rises with raising the concentration and diminishes with raising the temperature. The inhibition efficiency of 91.53 and 94.58 % were attained in the presence of the optimum concentration of 0.5 mM of ICS-10 and ICS-14, respectively. The activation energy (Ea) and heat of adsorption (Qads) were calculated and explained. Additionally, the synthesized compounds were investigated using density functional theory (DFT). Monte Carlo (MC) simulation was utilized to understand the mechanism of adsorption of inhibitors on the Fe (110) surface.

We all know that heat exchanger is one of the equipment to transfer the heat between the fluids. Heat will transfer from one side of fluid to another side of fluid. In this project we use counter flow heat exchanger. In this heat exchanger one kind of fluid will come from one side and another kind of fluid will come from another side. Both fluids will be sending inside to the tube in opposite direction. Here we are using two medium one is hot fluid and another one is APISN (American Petrol Institution of Super Natural) with B grade oil. Inside of apparatus we are using copper tube, to enhance the heat transfer. Because that copper is having higher thermal conductivity (385 W/m K). When we compared to the carbon steel (19 W/m K), copper is having more thermal conductivity. The reason for choosing copper tube is not only higher thermal conductivity; it's also having properties like corrosion resistance, max allows able stress and internal pressure. Hot fluid will be send through the way of inside of the copper tube. Over the copper tube will send APISN oil, both will be send in an opposite manner. In a setup of counter flow heat exchanger, we put two holes with some dimension. When the fluid goes inside of the tube we insert the digital thermo-meter to note down the temperature of both inlet and outlet. After taking all reading we will evaluate the counter flow heat exchanger with term of efficiency.

Problem statement. The formation of structural components starts with the hardening of steels. Therefore, it is important to investigate the influence of chemical composition, temperature of additional heating and cooling rate of the melt on the formation of structural components of steels. The purpose of the research – to compare the influence of the chemical composition, heating temperature and cooling rate on the formation of structural components in steels. Methods. To determine the features of the structural state of steels, we use microstructural analysis, X-ray microanalysis, X-ray diffraction method and surface etching of specimens with nital and hot solution of sodium picrate. Results. In the work, a study of steel specimens with different carbon, manganese and silicon content was carried out. We compared the structural state of steel in the cross-section of continuous cast steel billet and steel of a similar chemical composition after additional heating above the liquidus line at 50 °C, 150 °C and cooling at rates of 10–104 °C/s. Scientific novelty. It was found that in the process of manufacturing of continuous cast steel billets, when cooling in a crystallizer at the rate of ~104 ºС/s in the surface zone of the billet of steels with a carbon content of ≥ 0.5 wt.%, manganese ≥ 0.75 wt.% and silicon ≥ 0.45 wt.% the δ-ferrite formation and γ-iron dendrites formation from the melt are completely suppressed. For the first time, the effect of heating temperature above the liquidus line up to 150 °С and cooling rate of 10–103 °С/s on the structure formation of experimental carbon steels was investigated. It was established that additional heating above the liquidus line and cooling at rates of 102–103°C/s almost completely inhibits the formation of ferrite along the grain boundaries, enhances formation of a more uniform structure, an increase in the dispersion of structural components, simultaneous solid-solution and dispersion hardening of steel, and improvement of mechanical properties of steels. In addition, a decrease in the volume fraction of the areas containing liquation elements (manganese and silicon) was observed. The areas were distributed more evenly, which suggests that there could be a decrease in the difference in the content of chemical elements, compared to the condition without additional heating of the melt. Practical value. The use of the obtained results could allow to develop technologies for obtaining steels with a more uniform structure., Постановка проблеми. Формування структурних складових починається під час затвердівання сталей. Тому важливо дослідити вплив хімічного складу, температури додаткового нагріву та швидкості охолодження розтопу на формування структурних складових сталей. Мета дослідження − провести порівняння впливу хімічного складу, температури нагріву та швидкості охолодження на формування структурних складових в сталях. Методика. Для визначення особливостей структурного стану сталей використовували мікроструктурний, мікрорентгеноспектральний, рентгеноструктурний аналізи та травлення поверхні зразків ніталем та гарячим розчином пікрату натрію. Результати. Досліджено зразки сталей з різним умістом вуглецю, марганцю та кремнію. Порівнювали структурний стан сталі за перерізом БЛЗ та сталі близького хімічного складу після додаткового нагрівання вище лінії ліквідусу на 50 °С, 150 °С та охолодження зі швидкостями 10–104 °С/с. Наукова новизна. Встановлено, що в процесі виготовлення БЛЗ при охолодженні в кристалізаторі зі швидкістю ~104 ºС/с у поверхневій зоні заготовки зі сталей з умістом вуглецю ≥0,5 % (мас.), марганцю ≥0,75 % (мас.) та кремнію ≥0,45 % (мас.) відбувається повне пригнічення утворення δ-фериту та утворення з розтопу дендритів γ-заліза. Вперше досліджено виплив температури нагріву вище лінії ліквідусу до 150 °С та швидкості охолодження 10–103 °С/с на структуроутворення дослідних вуглецевих сталей. Встановлено, що додаткове нагрівання вище лінії ліквідусу та охолодження зі швидкостями 102–103 °С/с практично повністю пригнічують утворення фериту по границях зерен, сприяють утворенню більш однорідної структури, зростанню дисперсності структурних складових, одночасному твердорозчинному і дисперсійному зміцненню сталі та поліпшенню механічних властивостей сталей. Крім цього, спостерігали зменшення об’ємної частки ділянок, що містять ліквацію елементів (марганцю та кремнію). Ділянки були розподілені більш рівномірно, дозволяє припустити, що буде зменшення перепаду по вмісту хімічних елементів, порівняно зі станом без додаткового нагрівання розтопу. Практична значимість. Використання отриманих результатів дозволить розробити технології отримання сталей з більш однорідною структурою.

The purpose of this research was to discover the various reasons of failures and appropriate repair options for the line ducting cleaning unit system at PT Pusri Palembang's NPK-1 production facility. The main cause of the failures was determined to be a deterioration of the ducting line material caused by corrosion on the inner side of the ducting pipe composed of SS400 carbon steel. We made investigation including an analysis of the thickness of the damaged ducting pipe, as well as a visual check. The investigation showed that the corrosion caused an average drop in pipe wall thickness of up to 70%, according to the findings. The fixed load superimposed on the ducting pipe and the carrying capacity of the piping affect ducting strength, but corrosion on the inner surface of the pipe, caused by direct contact with corrosive and hygroscopic process dust, reduces ducting wall strength against axial and lateral loads. Failure of this ducting pipe caused losses and unscheduled shutdowns of production process, and increased the repair costs also could increase the risk of human accidents. The suggestion as this investigation results is to upgrade the ducting pipe materials to the more corrosion-resistant materials, such as stainless-steel grade SS304. Other suggestion should be taken is also regularly to inspect the ducting cleanness for the internal of ducting and control the dust flow rate through the scrubbing system. As conclusion, the suggestions given are to mitigate the risk of corrosion impact by maintaini­­­­­­ng ducting strength within the minimizing ducting system failures and ensuring the NPK plant's operation reliability.

The current state of regeneration of sulfate solutions was analyzed, it was established that the existing physico-chemical methods do not solve the problem of regeneration of sulfuric acid, but only neutralize it, for transfer according to the standards of the MPC to neutralization and into the sewage system with subsequent disposal. It has been confirmed that it is advisable to carry out the regeneration by an electrochemical method using a three-chamber electrolyzer, when the solution is fed into the middle chamber, the concentration of regenerated sulfuric acid increases to 180-200 g/l, with simultaneous iron deposition, with a current yield of 65-70%. This method reduces waste and allows switching to a closed cycle on sulfuric acid. It was found that in the process of digestion, the concentration of sulfuric acid decreases from 2.0 to 0.5 mol·dm-3, and the concentration of iron (II) sulfate increases accordingly. Under the conditions of a decrease in the concentration of sulfuric acid, its chemical activity also decreases when interacting with iron oxides and hydroxides. To increase the reactivity of pickling solutions, an increase in the temperature of the entire process is used. The kinetic regularity of combined cathodic processes in model solutions of iron (II) sulfate with sulfuric acid was established. Platinum, copper and carbon steel were used as cathode material. The choice of the cathode material was based on the different electrochemical properties of these selected metals with respect to the hydrogen reaction. The main process at the platinum cathode is hydrogen release in a wide range of current densities. At current densities greater than 0.1 A/cm2, a sharp increase in potential was observed due to the incorporation of Fe2+ into the composition of the cathode-electrolyte interface, but Fe2+ reduction potentials were not reached. When replacing the cathode material from platinum to carbon steel, a significant inhibition of hydrogen release was observed, which made it possible to reach the potentials for the simultaneous reduction of hydrogen and iron, however, the maximum current of the rectilinear section of the electrochemical process with electrochemical control was reduced from 10 at 20 0C to 3 times at 80 0C. The use of a copper cathode made it possible to reveal the influence of the hydrogen reaction on the course of Fe2+ reduction. The release of hydrogen at the copper cathode was accompanied by a significant inhibition of the hydrogen ion discharge. When using an iron cathode, electrochemical desorption is the limiting stage, which leads to the existence of layers of adsorbed hydrogen firmly attached to the surface of the iron cathode. A comparative analysis of the voltage-current dependences for the final investigated temperatures indicates a significant effect of an increase in temperature from 20 0C to 80 0C by approximately 120-150 mV. The cathodic process at 20 0C takes place in the mode of increased kinetics for both combined processes. At 80 0С, rectilinear sections of electrochemical control of the cathodic process appear on the voltage–voltage dependences, at Fe2+ concentrations of 1.0 and 1.5 mol/dm3. These areas range from 20 to 60 mA/cm2. The concentration of iron ions and the temperature of electrolysis have a significant effect on the process of electrochemical reduction of Fe2+, which was confirmed experimentally. Since the target process in the electrochemical regeneration of spent pickling solutions is the regeneration of sulfuric acid itself, and not the removal of Fe2+ from this solution, the cathodic mode of operation of the electrode unit was determined according to the technological indicators of the anodic process., Проаналізовано сучасний стан регенерації сульфатних розчинів, встановлено, що існуючі фізико-хімічні методи не вирішують проблеми регенерації сульфатної кислоти, а тільки нейтралізують її, для переведення за нормами ГДК на нейтралізацію та у систему стоків з подальшим захороненням. Підтверджено, що регенерацію доцільно проводити електрохімічним методом із застосуванням трьохкамерного електролізеру, коли розчин подається у середню камеру, концентрація регенерованої сульфатної кислоти зростає до 180-200 г/л, з одночасним осадженням заліза, з виходом за струмом 65-70 %. Такий метод знижує відходи та дозволяє перейти на замкнений цикл по сульфатній кислоті. З’ясовано, що в процесі травлення концентрація сульфатної кислоти зменшується від 2,0 до 0,5 моль·дм-3, а концентрація заліза (ІІ) сульфату відповідно зростає. За умов зниження концентрації сульфатної кислоти знижується і її хімічна активність при взаємодії із оксидами та гідроксидами заліза. Для збільшення реакційної активності травильних розчинів застосовується збільшення температури всього процесу. Була встановлена кінетична закономірність суміщених катодних процесів у модельних розчинах заліза (ІІ) сульфату з сульфатною кислотою. У якості матеріалу катоду використовували платину, мідь та вуглецеву сталь. Вибір матеріалу катоду ґрунтувався на різних електрохімічних властивостях цих обраних металів по відношенню до водневої реакції. Основним процесом на платиновому катоді є виділення водню в широкому діапазоні густин струму. При густинах струму більше 0,1 А/см2 спостерігалось різке зростання потенціалу через вбудову Fe2+ до складу межі розділу катод-електроліт, але потенціали відновлення Fe2+ не були досягненні. При заміні матеріалу катода з платини на вуглецеву сталь спостерігалося значне гальмування виділення водню, що дозволило досягти потенціалів сумісного відновлення водню та заліза, однак максимальний струм прямолінійної ділянки перебігу електрохімічного процесу з електрохімічним контролем скоротився від 10 при 20 0С, до 3 разів при 80 0С. Застосування мідного катоду дозволило виявити вплив водневої реакції на перебіг відновлення Fe2+. Виділення водню на мідному катоді перебігало зі значним гальмуванням розряду іонів водню. При застосування залізного катоду електрохімічна десорбція є лімітуючою стадією, що призводить до існування шарів адсорбованого водню міцно зчепленими із поверхньою залізного катоду. Порівняльний аналіз вольт-амперних залежностей для граничних досліджуваних температур вказує на значний вплив підвищення температури від 20 0С до 80 0С приблизно на 120-150 мВ. Катодний процес при 20 0С перебігає у режимі збільшеної кінетики для обох суміщених процесів. При 80 0С на вольт-амперних залежностях з’являються прямолінійні ділянки електрохімічного контролю катодного процесу, при концентраціях Fe2+ 1,0 та 1,5 моль/дм3. Ці ділянки простягаються від 20 до 60 мА/см2. Концентрація іонів заліза та температура електролізу має суттєвий вплив на процес електрохімічного відновлення Fe2+, що було підтверджено експериментально. Так як цільовим процесом при електрохімічний регенерації відпрацьованих травильних розчинів є регенерація саме сульфатної кислоти, а не видалення з цього розчину Fe2+ то катодний режим роботи електродного блоку був визначений за технологічними показниками перебігу анодного процесу.

In order to replace hazardous molten lead baths in the heat treatment of carbon steel wire with environmentally friendly fluidized bed furnaces a better understanding is needed of their heat transfer rates. There has been considerable work done in examining heat transfer rates to large cylinders immersed in fluidized beds, and some on wire sized ones as well, but all previous studies have been conducted on static cylinders. In order to gain a deeper understanding of heat transfer rates to a moving wire immersed in a fluidized bed furnace an apparatus has been constructed to move a wire through a fluidized bed. The heat transfer rates were calculated using the difference in inlet and outlet temperatures, wire speed and the bed temperature. As predicted, correlations for static wire were found to under-predict heat transfer rates at higher wire speeds, so a new correlation was developed by modifying an existing one.

International audience; This article reports investigations on the anoxic corrosion process impacting a carbon steel/ultrapure deaerated water system when it is exposed to gamma radiation (50 Gy h-1), and on the associated molecular hydrogen gas generation. On the one hand, a dynamic semi-open experimental setup allowing to distinguish between the H2 production related to water radiolysis and the one related to anoxic corrosion has been adopted to estimate the corrosion rate associated to three successive temporal phases: pre-irradiation, irradiation and post-irradiation phases. On the other hand, post mortem analyses performed on both liquid and solid samples permitted to (i) quantify the chemical changes occurring in solution due to the formation of water radiolysis products and (ii) observe and characterize the thin corrosion layer composed of magnetite (Fe3O4) at the surface of the metallic coupons. We show that gamma radiation induces a slight diminution of the carbon steel corrosion rate. However, by comparing the mean corrosion rate values obtained for the three studied phases (i.e., before, during and after irradiation), the chemical changes caused by radiolytic species seem to inhibit the formation of a thick magnetite protective layer. Additionally, the corrosion rate observed in post-irradiation phase does not decrease over time, which suggests that irradiation could modify the properties of the corrosion product layer by making it less protective. A structural modification of this oxide film might be caused by the oxidizing water radiolysis products. Such mechanisms may favour continuous active corrosion processes rather than passivation of the metallic surface and thus lead to a reduced lifetime of the component.

During the mandatory acidification process in the oil and gas industry, carbon steel unfortunately suffers significant corrosion damage. From this perspective, for the first time a new ionic liquid called 1-(2-(4-bromophenyl)-2-oxoethyl)-4-(tert-butyl)pyridin-1-ium bromide (ILB) has been used as an effective inhibitor for the carbon steel corrosion in aggressive HCl solution (15%) at 298 K. The experiments were managed with a number of different chemical and electrochemical techniques including weight loss, potentiodynamic polarization (PDP), and impedance spectroscopy (EIS). ILB has good inhibitory performance as an acidizing corrosion inhibitor for carbon steel even at low dosing levels of 1 × 10−3 M. The findings were promising as an inhibition efficiency of about 97% was achieved when ILB was added at low concentrations to the corrosive media. EIS results showed a significant rise in charge transfer resistance (Rct) values with increasing doses of ILB. PDP studies confirmed that ILB is a mixed type and obey Langmuir adsorption isotherm with chemical nature. The metal surface morphologies were inspected using a Scanning Electron Microscope (SEM) and an Atomic Force Microscope (AFM). Additionally, Density Functional Theory (DFT) and Molecular Dynamic Simulation (MDS) indicates that ILB molecules function as inhibitors more successfully. There is a high degree of concordance between practical and theoretical studies.

This research analyses the viability of using cryogenic cooling combined with MQL (minimum quantity lubrication) lubrication, under CryoMQL technology, as a cutting fluid in the industrial environment to justify the increase in the environmental footprint generated by its use compared to MQL in stand-alone mode. For this analysis, a set of milling tests were carried out on carbon steel AISI 1045, which is one of the most commonly used materials in the business day-to-day. In this set of tests, the evolution of cutting edge wear and energy consumption of both technologies were recorded to check their tool life through technological and environmental analysis. Thus, we sought to discern whether the energy savings derived from the machining process make up for the greater environmental footprint initially generated by the use of CryoMQL technology itself. The results obtained show how the use of CryoMQL not only increased tool life, but also allowed an increase in productivity by increasing cutting speeds by 18%; in other words, thanks to this technology, a more technologically advanced and environmentally friendly process is obtained. By increasing tool life by 30%, a reduction in energy consumption is achieved together with cost savings, which implies that ECO2 machining has economic and ecological benefits.

In order to evaluate the effect of chromium content in carbon steel on the corrosion resistance of carbon steel materials, the corrosion behavior of 1Cr and N80 steels was investigated in this study by immersion weight loss method under three different CO2 partial pressure and temperature conditions in formation water for 72, 168 and 336 h. Detailed material surface morphological characterization was performed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and confocal laser scanning microscopy (CLSM). The results show that the pitting corrosion of N80 carbon steel is serious at medium temperature and low CO2 partial pressure (50 °C, 0.30 MPa), and the corrosion rate is significantly higher than that of 1Cr steel. However, at high-temperature and high CO2 partial pressure (100 °C/0.63 MPa and 114 °C/0.73 MPa), 1Cr steel is more inclined to the mesa corrosion dominated by local corrosion characteristics, and the corrosion rate is seriously higher than that of N80 steel with uniform corrosion. From the experimental results, we can know the corrosion resistance of carbon steel and 1Cr steel is not only affected by the corrosion environment, but also depends on the formation process of the product film, as well as its compactness and integrity characteristics. At low-temperature and low CO2 partial pressure, 1 wt.% chromium content can provide a certain degree of corrosion resistance, while high temperature and high partial pressure can broaden the application window of carbon steel N80 and weaken the corrosion inhibition effect of chromium.

Corrosion is one of the major issues we face today, hence, this research work was designed to determine the rate of corrosion of carbon steel in different aqueous environments. The correction is induced by the exposure of the carbon steel to different location or environment such as sea water environment, fresh water and alkaline environment, which contains oxygen and water, since these are one of the major agents of corrosion. This is based on the experiment which involves the immersion of carbon steel into these exposed locations and effect of different corrosion was considered. The exposure time varies between 7, 14, 21, 28, 35, 42, 49, 56, 63 and 70 (days), respectively. From this research, the behavior of corrosion of carbon steel have been examined and investigated based on the exposed location or environment and results revealed that the environmental conditions and corrosion agents has variable impact on the carbon steel.

International audience; ToF-SIMS and XPS are combined to study the adsorption of tetradecyl-benzyldimethyl-ammonium (BDA-C14) bromide corrosion inhibitor on carbon steel surface. BDA-C14 forms a protective layer with N-containing polar head group interacting with carbon steel surface. The adsorbed inhibitor surface coverage strongly depends on immersion time and inhibitor concentration. A maximum and uniform coverage is found for sufficiently long exposure times at a critical inhibitor concentration of about 25 ppm w. The uniform adsorbed inhibitor layer formed on the surface mitigates the formation of iron chloride/hydroxide intermediates and thus enhances the corrosion protection of carbon steel in aggressive environment.

The corrosion inhibition properties of three spiro-isoxazoline derivatives, namely 3,4-diphenyl-1,7-dioxa-2-azaspiro[4.4]non-2-en-6-one (DDA), 3-phenyl-4-(p-tolyl)-1,7-dioxa-2-azaspiro[4.4]non-2-en-6-one (PDA) and 4-(4-methoxyphenyl)-3-phenyl-1,7-dioxa-2-azaspiro[4.4]non-2-en-6-one (MDA) on carbon steel in 1.0 mol/L HCl acid medium were experimentally and computationally investigated. The experimental results showed that the inhibitory efficiency reached remarkable values of 76.26, 80.31, and 82.91%, respectively, for DDA, PDA and MDA at a maximum concentration of 10−3 mol/L. The potentiodynamic polarization curves (PPCs) showed that investigated compounds had a mixed type character, controlling both anodic and cathodic corrosion reactions. In addition, electrochemical impedance spectroscopy (EIS) indicated that the addition of increasing concentration of tested compounds to HCl solutions led to a significant increase in the polarization resistance of the carbon steel, which was accompanied with a simultaneous decrease in the double layer capacitance. On the other hand, the morphological study of the metal surface by scanning electron microscope (SEM) and energy dispersive X-ray (EDX) confirmed the effective protection of the carbon steel by the inhibitors against corrosion through the formation of a protective film on its surface. The adsorption characteristics of investigated compounds on carbon steel were assessed at microscopic level using Density Functional Based Tight Binding (DFTB) simulation, which revealed the formation of covalent bonds between inhibitors’ atoms and Fe atoms. Furthermore, additional insights into the compounds’ reactivity and adsorption configurations on steel surface were obtained from global reactivity descriptors and Monte Carlo simulation. The present work’s outcomes are interesting for further design and performance evaluation of effective organic corrosion inhibitors for acid environments.

This paper investigates the deposition of calcareous material on carbon steel through cathodic protection. A Response Surface Methodology (RSM) was applied to model the electrodeposition of calcareous material in ASTM seawater by varying temperature and current density parameters. The calcareous deposit was more compact at a current density ≤ 150 µA/cm2. At least 55 µA/cm2 current density was required to provide cathodic protection and initiate electrodeposition, thus inhibiting corrosion. Furthermore, the produced RSM models can predict the amount and composition of the material at 55 – 310 µA/cm2 current density and 4 – 25 °C temperature.

Ni/Co/SiO2 hydrophobic coatings were fabricated by embedding SiO2 nanoparticles into Ni/Co coatings using pulsed electrodeposition, followed by a liquid-phase hydrophobic treatment. Microstructure and morphology analysis of the composite coatings revealed that the SiO2 nanoparticles were homogenously distributed in the Ni/Co coating, and the surfaces of the samples were close-grained without crack. Furthermore, the SiO2 nanoparticles in the coating formed micro-nano structures on its surface, such that the contact angle reached 125° following the hydrophobic modification. The surface of the hydrophobic coating was found to be abrasion resistant and exhibited long-term stability in water. The corrosion inhibition efficiency of the Ni/Co/SiO2 hydrophobic coatings on a Q235 carbon steel substrate in simulated seawater solution reached 98.6%, indicating optimal anti-corrosion performance.

In this research work, samples of low carbon steel AISI 1017 subjected to shot peening process for 15 minutes. These samples were cleaned and coated with epoxy. The coating process were carried out with epoxy, epoxy mixed with alumina powder, epoxy mixed with silicon carbide powder and the last case, the steel coated with epoxy mixed with alumina and silicon carbide powders. Results showed that the corrosion resistance of steel coated with epoxy and alumina were better as compared with other samples .

Background: Curcumin-stabilized silver nanoparticles (Cur-AgNp) synthesized by a facile chemical method. The synthesized AgNp was, for the first time, used as a bio-derived corrosion inhibitor for carbon steel in the 1M sulphamic acid medium. Methods: The electrochemical studies via impedance spectroscopy, potentiodynamic polarization, and surface analysis are reported in the communication. The maximum inhibition efficiency of 92.87% obtained at 800 mgL-1 . Results: The impedance measurements revealed an elevation in the polarization resistance with growth in the inhibitor concentration, which supports the adsorption and inhibition behavior of Cur-AgNp on the steel surface. The inhibitor functioned by adsorption on the steel surface and obeyed the Langmuir kinetic-thermodynamic isotherm with a mixed mode of physical/ chemical adsorption. The potentiodynamic polarization study revealed cathodic predominating behavior. Conclusion: The SEM analysis depicted the development of a protective inhibitor film on the steel substrate, and FTIRATR analysis of the inhibited steel surface supported the adsorption of the corrosion inhibitor on the metallic surface.

In this study, individual Al2O3 and Cr2O3 coatings and Cr2O3-25, 50, 75 wt% Al2O3 composite coatings were applied on carbon steel by atmospheric plasma spraying method. Corrosion experiments were performed on as-sprayed and epoxy resin sealed coatings including potentiodynamic polarization, electrochemical impedance spectroscopy and long-term immersion in 3.5 wt% NaCl solution. Phase composition and microstructure of the coatings were investigated by x-ray diffraction, optical microscopy and scanning electron microscopy, before and after the corrosion experiment. The results showed that the Cr2O3 coating exhibited the best corrosion resistance, due to the densest microstructure and highest adhesion strength. The Cr2O3-25 wt% Al2O3 coating had the highest interconnected porosities and thus had the least corrosion resistance compared to other coatings. In general, the as-sprayed coatings induced a maximum increase of 3.93 times the polarization resistance (Rp) in the polarization experiment and a 3.5 times increase in the charge transfer resistance (Rct) in the EIS experiment, which was not significant. Stresses caused by increased volume of corrosion products in the coating-substrate interface resulted in the spallation of Cr2O3-25, 50 wt% Al2O3 coatings from the substrate over long-term of immersion. The adhesion strength of the coatings was a determining criterion for the long-term durability of the coatings. The sealing treatment resulted in a significant increase in Rp and Rct.

Stainless steel reinforcing rebars and prestressing strands are viable alternatives to carbon steel materials for prestressed concrete structures in extremely aggressive environments. They offer better durability and require less maintenance. This study experimentally investigated the transfer length and prestress losses of 15.2-mm- (0.6-in.-) diameter Duplex High-Strength Stainless Steel (HSSS) strands as well as the shear and flexural behavior of two full-scale 12.8-m- (42-ft-) long AASHTO Type II concrete girders prestressed with HSSS strands and reinforced with duplex stainless steel rebars. The girders were made composite by adding a deck slab. One girder was tested in shear at both ends while the other girder was tested in flexure. Experimental shear and flexural behavior of the girders exhibited a constant increase in load carrying capacity up to failure. The failure mode for the shear tests was web shear, and for the flexural test was rupture of the HSSS strands. Both girders tested in shear and flexure failed in a progressive manner as they exhibited adequate warning through noticeable deflection, excessive cracking, and large reserve strength from first cracking to failure. The applicability of AASHTO LRFD provision for stainless steel reinforcing materials was investigated. AASHTO LRFD equations for flexural resistance were modified to cover rupture of strand failure mode. Experimental shear strength and flexural strength of the girders were greater than the predicted values by AASHTO shear equations and modified AASHTO flexural equations, respectively.

In this present research, optimization of spot-welding process parameters was done on the low carbon steel grade (JSC 590RN) using Taguchi L18 methodology. The main process parameters of spot welding namely electrode diameter (d), electrode force (F), welding current (I) and weld time (t) are taken to determine the quality characteristics of the joint. Heat affected Zone (HAZ), Nugget diameter (N-D) and tensile strength were taken as a quality characteristic for the improvement. For experimental trials, Taguchi L18 was selected. The GRA technique was used to observe the level of importance of process factors on spot welding. ANOVA results show that amid all control factors, welding current (39.19%) is the highest participating followed by weld time (23.81%). In this experiment, the confirmation result shows that it is possible to increases the weld quality up to 12.0081%.

Many industrial parts degrade, which reduces plant reliability. Waterwall tube is part of the circulating fluidized bed (CFB) boiler that often degrades caused by the bed materials’ erosion. Therefore it requires a material with resistance to corrosion, abrasion, and high oxidation and economically feasible. One of the solutions is to coat the tube with hard ceramic materials by using thermal spraying. In this present work, composites of NiCrBSi-SiC were used to coat low carbon steel in order to study the possibility of used in boiler application. The coating process was carried out using the high-velocity oxygen fuel (HVOF). The amount of SiC was varied from 0% to 40% SiC to study their effect on coating properties. Then microstructure examination was done using an optical microscope on the surface with a cross-section to see the coating results in the form of density, porosity, and the bond between the layer and the substrate. Hardness testing with the Vickers method was carried out on the cross-section to determine the hardness value of the coating. The oxidation test is carried out to determine the oxidation resistance of the coating at high temperatures. Results show that the addition of SiC will increase the hardness and oxidation resistance. The porosity that appears is influenced by the SiC powder that does not melt entirely during the coating process due to differences in particle size. The amount of porosity will also affect the oxidation resistance of the coating.

This paper investigates the accuracy of different design equations given in design specifications and literatures in determining the block shear strength of the lean duplex stainless steel fillet welded connections with base metal fracture. It points out the problem inherent in the block shear provision specified in the North American cold-formed design specification, which does not consider shear strain hardening. The previous test results have found that full shear strain hardening can be assumed for the carbon steel and ferritic stainless steel welded connections, but not applicable to the thin-walled lean duplex stainless steel welded connections with a higher ratio of the tensile strength to yield stress. Based on the results of finite element analysis including ductile damage simulation, this study reveals that the block shear strength of the lean duplex stainless steel specimens can be determined accurately using the mean between the shear yield stress and the shear ultimate stress. This paper also investigates the effect of stress triaxiality incorporated in the block shear equations found in the literature through comparative analysis with the bolted connection. The effect is shown to be negligible for the thin-walled lean duplex stainless steel welded connection, although higher stress triaxiality is developed in welded connection than in bolted connection. This paper recommends a block shear equation assuming the normal tensile stress in the net area in conjunction with partial shear strain hardening. The recommended equation was found to be more accurate than other equations for determining the block shear strength of the thin-walled lean duplex stainless steel welded connections.

Corrosion inhibition of Pelargonium (Pe) and Citrus reticulata (Cr) oil concentrates and their admixture (PeCr) on 1018 carbon steel (18CS) was studied in 0.5M H2SO4 and HCl media with electrochemical polarization technique, potential-time evaluation (OCP), coupon computation, optical image assessment, ATF-FTIR spectroscopy and X-ray diffractometry. Polarization data showed Pe performed effectively only at the highest concentrations in H2SO4 (3% and 3.5%) with optimal inhibition performance of 91.56% while in HCl effective corrosion inhibition occurred at all concentrations considered with optimal value of 87.32% at 2.5% concentration. Cr concentrate performed adequately at all concentrations in H2SO4 and HCl solutions with utmost values of 78.12% and 91.87%. PeCr performed more efficiently at all concentrations in HCl with utmost value of 95.46%. PeCr utmost inhibition performance in H2SO4 was below 70%. Coupon measurement showed the concentrate performances in HCl are independent of time/concentration, and generally attained stability from 72 to 96 h of exposure. This contrast their performance in H2SO4 which is significantly dependent on time/concentration. OCP plots shows the presence of Pe in H2SO4 and HCl, Cr in H2SO4 and PeCr in H2SO4 heightens the thermodynamic tendency of 18CS to corrode in view of its optimal inhibition outputs compared to Cr and PeCr in HCl whose plots decreased the thermodynamic tendency. ATF-FTIR data depict significant decrease in transmittance of reactive groups for Cr in H2SO4 and HCl media at all wavenumbers due to adsorption. Transmittance of Pe and PeCr concentrates reactive groups increased after corrosion signifying the nature of their inhibition mechanism. Optical representations of protected and non-inhibited 10CS surfaces substantially differed from each other. X-ray diffractometry identified corrosive precipitates on the steel without concentrate addition. In the presence of the concentrates, in the presence of the concentrates the phases compounds identified on the inhibited steel were non-corrosive.

Flow accelerated corrosion (FAC) is a type of pipe corrosion in which the pipe thickness decreases depending on the fluid flow conditions. In nuclear power plants, FAC mainly occurs in the carbon steel pipes of a secondary system. However, because the temperature of a secondary system pipe is over 150 °C, in situ monitoring using a conventional ultrasonic non-destructive testing method is difficult. In our previous study, we developed a waveguide ultrasonic thickness measurement system. In this study, we applied a waveguide ultrasonic thickness measurement system to monitor the thinning of the pipe according to the change in pH. The Korea Atomic Energy Research Institute installed FAC-proof facilities, enabling the monitoring of internal fluid flow conditions, which were fixed for ~1000 h to analyze the effect of the pH. The measurement system operated without failure for ~3000 h and the pipe thickness was found to be reduced by ~10% at pH 9 compared to that at pH 7. The thickness of the pipe was measured using a microscope after the experiment, and the reliability of the system was confirmed with less than 1% error. This technology is expected to also be applicable to the thickness-reduction monitoring of other high-temperature materials.

This study addresses the influence of material variations on the grindability of crankshaft steel. Most previous studies on the effect of material microstructure on grindability involve comparisons of significantly different steel grades. This study, in contrast, is focused on batch-to-batch grindability variations for one steel grade, a scenario frequently occurring in industry where batches from different steel makers are fed into a production line. For this purpose, a batch made of recycled steel and a batch made of ore-based steel were compared with regards to microstructure and grindability under identical grinding and dressing conditions. Although both batches met the same material specifications, microstructural variations were identified in terms of grain size and micro-constituents (inclusions, carbonitrides). While specific grinding energy, residual stress and full-width at half-maximum profiles of ground surfaces were the same for both batches, the recycled batch showed different and unfavorable variation in wheel wear and Barkhausen noise (BN) response. Larger fractions of oxide inclusions and larger grain sizes (affected by carbonitrides) were present in the recycled batch, which were the likely reasons for the differences in wheel wear and BN response, respectively. These findings may aid grindability improvement by steel-grade adjustments, e.g. modification of the distribution and type of inclusions and/or amount of elements forming carbonitrides. Furthermore, the results highlight the importance of understanding and controlling material microstructure, as existing in-line quality by BN control may not always be able to correctly indicate surface integrity, which could lead to misinterpretations (e.g. false part-rejection on the assumption of grinding burn).

The corrosion behaviour of J55 steel in typical high-water-cut oil wells and the inhibition effects of different types of corrosion inhibitors were investigated. Using electrochemical experiments, the effects of temperature, Cl−, HCO3−, Ca2+, Mg2+ and pH on the corrosion of J55 steel were studied. Under experimental conditions, the corrosion rate slowed with increasing pH value when the temperature increased from 35 °C to 70 °C. The corrosion rate also increased first and then decreased with increasing Cl−, Ca2+ and Mg2+ ion concentrations, which notably affected the distribution of corrosion pits on the surfaces of the steel. The protection performances of various corrosion inhibitors and corrosion products were evaluated through electrochemical measurements. The results showed that the CT-2, UT2-2 and YC-2 inhibitors had obvious effects on the corrosion prevention of the J55 steel. In particular, the corrosion inhibition efficiencies of the three kinds of carbon steel were remarkable and exceeded 84% when the UT2-2 concentration reached 0.18 g/L.

The anti-corrosion behaviour of the expired Tobramycin (ETo) drug for carbon steel in 2 M HCl solution was investigated by thermometric methods (Thermo), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The results obtained from Thermo, PDP and EIS show that the level of anti-corrosion behaviour is in direct association to the ETo application. The model of adsorption isotherm fitted Langmuir, confirming a chemical adsorption system. The SEM image of carbon steel immersed in optimum concentration of ETo has confirmed the film formation on the carbon steel surface. The PDP technique, indicated by the Tafel plots, demonstrated that the ETo inhibitor acted as a mixed-type inhibitor. The results obtained from activation energy, Ea, the quantity of heat adsorbed, Qads, and standard free energy of adsorption, AG°ads, show a chemical adsorption mechanism of the ETo inhibitor.

Pyroxene glass-ceramic enamels based on combinations of blast furnace slag and some additives were produced and investigated. The batch compositions and technological regimes of enameling were developed to produce high temperature protective coatings for carbon steel (ASTM 1010/1008). The composition of raw materials was selected to match the values of the thermal expansion coefficients of the glass-ceramic coating (~11∙10−6 K−1) and metal substrate (~12∙10−6 K−1) taking into account the temperatures of fluidization (Tf ~ 800°) and crystallization (Tc = 850−1020 °C) of the corresponding glasses. The covered and thermally treated samples of carbon steel were produced using single-layer enameling technology and investigated to specify structure, phase composition and properties of the coating and coating-steel interface. The obtained coatings were characterized with excellent adhesion to the steel (impact energy ~3 J) and protective properties. The closed porous structure of the coatings promoted low thermal conductivity (~1 W/(m·K)) and high (up to 1000 °C) thermal resistance, whereas the pyroxene-like crystalline phases supported high wear and chemical resistance as well as micro-hardness (~480 MPa) and thermal shock resistance (>30 cycles of 23–700 °C). The obtained cheap coatings and effective protective coatings could be used at the temperatures up to 1100 °C in the corrosive atmosphere and under the action of abrasive particles.

Polymer–Clay Nanocomposite (PCN) coatings were prepared using the solution intercalation method. The raw Khulays clay was treated with NaCl to produce sodium clay (NaC). Thereafter, Cetyl Pyridinium Chloride (CPC) was used to convert NaC into the organic clay form (OC). PCN was prepared by adding polystyrene as the matrix to different weights of OC to prepare 1 wt.% and 3 wt.% PCN. To enhance the coating protection of C-steel in NaCl solution, PCN coatings were added to microcapsules loaded with some corrosion inhibitors PCN (MC). The microcapsules are prepared by the encapsulation of rare-earth metal Ce+3 ions and Isobutyl silanol into polystyrene via the Double Emulsion Solvent Evaporation (DESE) technique. Characterization techniques such as FTIR, X-Ray Diffraction (XRD), and Transmission Electron Microscopy (TEM) were employed. FTIR confirmed the success of the preparation, while XRD and TEM revealed an intercalated structure of 1 wt.% PCN while 3 wt.% PCN has a fully exfoliated structure. Electrochemical Impedance Spectroscopy (EIS), Electrochemical Frequency Modulation (EFM), and Potentiodynamic Polarization showed an enhanced protection efficiency of PCN (MC) coatings. The results demonstrated that the corrosion resistance (RCorr) of 3% PCN (MC) coating was higher than all the formulations. These PCN (MC) coatings may provide corrosion protection for C-steel pipes in many industrial applications.

The paper is focused on analysing the pearlitic steel phase transformations and their influence on the mechanical properties. The intention is to perform a detailed analysis of the heat treatment process using the exact heating temperature and chemical composition to achieve the optimal mechanical properties of the tool. The key area is monitoring and regulating the heat treatment. This technology is constantly undergoing an optimisation process and is an effort to introduce new trends in monitoring phase transformations and processes. The use of non-destructive methods is an adequate tool. The principle is to determine the exact structural phase at a given moment, which can be very difficult when a complex shaped part is heat treated. Which precludes the use of some other methods of phase transformation analysis. Specifically, the determination of the exact moment of finish of the austenitisation process is eminent. The monitoring of these processes will be ensured by both a non-contact pyrometer and also by the AE method with an adequate sensor and waveguide. The resulting structural phases formed after the heat treatment will be evaluated by electron microscopy, followed by the analysis of the mechanical properties of selected steels. Článek je zaměřen na analýzu fázových přeměn perlitické oceli a jejich vlivu na mechanické vlastnosti. Záměrem je provést podrobnou analýzu procesu tepelného zpracování s využitím přesné teploty ohřevu a chemického složení pro dosažení optimálních mechanických vlastností nástroje. Klíčovou oblastí je sledování a regulace tepelného zpracování. Tato technologie neustále prochází optimalizačním procesem a je snahou zavést nové trendy ve sledování fázových přeměn a procesů. Adekvátním nástrojem je použití nedestruktivních metod. Principem je určení přesné konstrukční fáze v daném okamžiku, což může být při tepelném zpracování složitého tvarového dílu velmi obtížné. Což vylučuje použití některých jiných metod analýzy fázových transformací. Významné je zejména určení přesného okamžiku ukončení procesu austenitizace. Sledování těchto procesů bude zajištěno jak bezkontaktním pyrometrem, tak i metodou AE s adekvátním senzorem a vlnovodem. Výsledné strukturní fáze vzniklé po tepelném zpracování budou vyhodnoceny elektronovou mikroskopií s následnou analýzou mechanických vlastností vybraných ocelí.

Explosive plating, or welding, is a process where part of the kinetic energy of the detonation of a certain amount of civil explosive material is used to accelerate the plate, which will form a welded joint upon an oblique impact on a stationary plate. The conditions that must be met to achieve a good weld are determined by welding criteria. Today, the most commonly used welding criteria are based on the speed of the collision point and the collision angle. In this paper a research is presented on explosion welding of two different steels and on quality of the obtained welded joint. Carbon steel and spring steel were welded using Amonex 4 explosive in different quantities. Basic characterization of the explosive was carried out: bulk density and detonation velocity were determined. Quality of the welded joint was inspected using the ultrasonic method. Possible intermetallic zones at the joint site created by the effect of increased temperature were examined by optical and scanning electron microscopy. Fracture toughness of the welded plates was determined, as well as hardness. The achieved experimental results were compared to theoretical predictions.

In order to clarify the effect of environmental factors on the atmospheric corrosion of steel, novel model for predicting the reduction of atmospheric corrosion considering relative humidity and rain falls was developed. We conducted a one-year calculation simulation of atmospheric corrosion in Miyakojima City, Choshi City, and Tsukuba City using the developed model. Corrosion weight loss by the simulation could reproduce the measured value well. Corrosion weight loss was greatly affected by the amount of airborne sea salt, relative humidity, and rain falls.

Stainless steel (SS) is increasingly used for structural applications in the construction industry as its beneficial properties outweigh initial material costs when sustainability aspects and the whole life cycle of structures are appropriately accounted for in the structural design. Despite the well-recognised significance of connections in bare metallic construction, experimental research on SS beam-to-column connections, especially full-scale test results, are scarce. This paper presents a full-scale experimental investigation on the semi-rigid behaviour of top-seat bolted connection (also known as ‘flange cleat’ connection) made from austenitic SS. Deformation characteristics of various elements of the connection were carefully investigated and subsequently used to calibrate nonlinear FE models for parametric analysis. Obtained numerical results were used to develop a four-parameter power model that relies on simplified expressions for key input parameters to predict the semi-rigid behaviour of bolted top-seat connections. Results predicted using the proposed model and those obtained using currently available techniques based on carbon steel behaviour were compared. Outcomes of the current research highlighted the significance of appropriate inclusion of stain hardening offered by austenitic grade to capture the semi-rigid response of such connections.

Raman micro-spectroscopy was conducted for in-situ observation of atmospheric corrosion occurring on carbon steel surfaces, on which NaCl nanoparticles with a size of < 1 mu m were deposited, under the controlled relative humidity at room temperature. Increasing relative humidity induced the formation of amorphous-FeOOH at a micro-droplet of NaCl solution where an NaCl nanoparticle was dissolved on the steel surface, and the initiation time of the corrosion generation decreased with increasing relative humidity. Drying treatment at 100 degrees C for 600 s resulted in modification of the surface condition of carbon steels and obstructing the corrosion initiation at high humidity conditions but reducing the initiation time at low humidity conditions.

The efficiency of Syzygium cumini leaf extract (SCLE) as a corrosion inhibitor was evaluated for carbon steel in 0.5 mol L−1 H2SO4 by potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) measurements. It was clearly demonstrated that the inhibition efficiency increased with increasing concentration of leaf extract, due to a decrease in the cathodic currents and blocking of the active corroding sites. The presence of organic molecules from the SCLE on the carbon steel surface was confirmed by FT-IR spectroscopy. The adsorption of species on the alloy surface was modeled using the Langmuir isotherm. A decrease in the carbon steel acid corrosion in the presence of SCLE was also confirmed through contact angle measurements and scanning electron microscopy (SEM).

Effects of metal cations on the corrosion behavior of carbon steel SM490Y in 10 mM Cl- model fresh water were investigated by immersion tests, electrochemical tests, and surface analysis. Immersion tests and electrochemical tests results showed that Zn2+ had a significant inhibition effect on corrosion of SM490Y. The results of EDS and XPS showed that Zn2+ was incorporated in the oxide films by making a strong bond and formed zinc hydroxide or zinc oxide which can cover the surface of carbon steel. It is suggested that Zn2+ forms a protective film which can efficiently prevent break down of surface film by Cl- and inhibit the corrosion.

Background Carbon steel is an important industrial material; its corrosion and protection are attracting more attention from researchers. The use of advanced corrosion inhibitors is widespread due to their accessibility, convenience, and high-efficiency characteristics. In this account, for the first time, the leaves of Achillea Millefolium were extracted using ultrapure water, and the synergistic action of Achillea Millefolium Extract (AME) with zinc ion for carbon steel corrosion in 3.5% NaCl solution was evaluated. Methods Polarization and electrochemical impedance spectroscopy (EIS) experiments were utilized to assess the suggested mixture's inhibition activity. Surface characterizations were carried out using ultraviolet-visible (UV-Vis) analysis, scanning electron microscope (SEM) equipped with EDX, Fourier transmission infrared (FTIR) spectroscopy, contact angle (CA) examination, and grazing incidence X-ray diffraction (GIXRD). Furthermore, DFT and molecular dynamics (MD) simulations were used to explain the inhibition mechanism at the atomic or molecular level. Significant Findings A combined protection attitude was identified, and for 500 ppm Zn + 500 ppm AME, the inhibition effectiveness was 93.49%. Polarization results suggest that the complex behaves as a mixed-type inhibitor, which simultaneously suppresses cathodic and anodic reactions. Surface analysis confirms the protective hydrophobic film formed on the steel surface, all of which demonstrate the outcomes of the electrochemical examination. Our work can provide a theoretical reference for further research on metal-organic-based corrosion inhibitors.