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The Importance of Structure and Corrosion Resistance of Steels/Alloys

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Coatings 2022, 12(7), 997; https://doi.org/10.3390/coatings12070997 - 15 Jul 2022

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Abstract

Steels/alloys are widely used in various aspects of human society, such as transportation and construction, machinery manufacturing, oil, chemical, petrochemical, marine, and nuclear power industries, etc [...] Full article

(This article belongs to the Special Issue Investigation on Structure and Corrosion Resistance of Steels/Alloys)

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Open AccessArticle

Corrosion Resistance of Fe-Cr-Si Alloy Powders Prepared by Mechanical Alloying

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Coatings 2023, 13(10), 1679; https://doi.org/10.3390/coatings13101679 (registering DOI) - 25 Sep 2023

Viewed by 54

Abstract

Powders with nanometric crystallites of two ternary alloys Fe

_{0.90}

Cr

_{0.05}

Si

_{0.05}

and Fe

_{0.85}

Cr

_{0.10}

Si

_{0.05}

were prepared by mechanical alloying (MA) in a planetary high-energy ball mill at various milling times followed by annealing in a vacuum [...] Read more.

Powders with nanometric crystallites of two ternary alloys Fe

_{0.90}

Cr

_{0.05}

Si

_{0.05}

and Fe

_{0.85}

Cr

_{0.10}

Si

_{0.05}

were prepared by mechanical alloying (MA) in a planetary high-energy ball mill at various milling times followed by annealing in a vacuum at 900 K to induce an oxygen-induced surface segregation of Cr and Si atoms. The prepared powders were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The obtained results show that all prepared powders crystallize in the body-centered cubic structure and are composed of micrometric particles, which are polycrystalline and consist of many nanometric crystallites. The mean size of the particles as well as the crystallites decreases progressively with milling time. In order to study the anti-corrosion properties of the obtained materials, the powders were exposed to atmospheric gases at 870 K. After each oxidation step, the formation of iron oxides was investigated using

^{57}

Fe transmission Mössbauer spectroscopy (TMS). It was found that the powders of Fe

_{0.90}

Cr

_{0.05}

Si

_{0.05}

and Fe

_{0.85}

Cr

_{0.10}

Si

_{0.05}

obtained after 10 and 20 h of MA are extremely resistant to oxidation. This result can be connected with the fact that XPS measurements reveal a high concentration of Cr and Si atoms on the surface of powder particles. Full article

(This article belongs to the Special Issue Investigation on Structure and Corrosion Resistance of Steels/Alloys)

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Open AccessArticle

Experimental Study of Surface Damage of Stainless Steel Subjected to Cavitation Collapse in Aqueous Environment

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Coatings 2023, 13(8), 1356; https://doi.org/10.3390/coatings13081356 - 02 Aug 2023

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Abstract

With the aim of understanding cavitation damage of stainless steel under the effect of cavitation collapse in an aqueous environment, morphology, phase, chemical state, electrochemical, and other properties after cavitation and erosion are methodically examined. The obtained results indicate that the addition of [...] Read more.

With the aim of understanding cavitation damage of stainless steel under the effect of cavitation collapse in an aqueous environment, morphology, phase, chemical state, electrochemical, and other properties after cavitation and erosion are methodically examined. The obtained results indicate that the addition of metal ions in pure water strengthens the dynamic effect of cavitation collapse. When the cavitation collapses, it is capable of releasing a high temperature and transferring it to the surface of the stainless steel in a short time. Then, through the rapid cooling of the pure water environment, the martensitic structure is generated, but the presence of a massive amount of metal ions leads to a decrease in the speed of heat conduction and absorption of some heat. After the collapse of the bubble, the passivation film on the surface of the stainless steel incorporates into the creation of initial micropores. A concentration difference and a growth of the current density at the bottom of the hole, as well as a reduction in the pH value are detectable. Compared with pure water, 3.5% NaCl solution contains more free ions and its local current density is higher, so its corrosion resistance is worse. Full article

(This article belongs to the Special Issue Investigation on Structure and Corrosion Resistance of Steels/Alloys)

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Open AccessArticle

Low-Potential Zone at the Interface of Precipitate and Austenite Affecting Intergranular Corrosion Sensitivity in UNS N08028 Nickel–Iron–Chromium Alloy

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Coatings 2023, 13(8), 1304; https://doi.org/10.3390/coatings13081304 - 25 Jul 2023

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Abstract

The precipitates and the intergranular corrosion behavior of a UNS N08028 nickel–iron–chromium alloy sensitized at different temperatures were studied by employing transmission electron microscopy, Kelvin probe force microscopy and other methods. It was found that sigma precipitates appeared at the grain boundaries of [...] Read more.

The precipitates and the intergranular corrosion behavior of a UNS N08028 nickel–iron–chromium alloy sensitized at different temperatures were studied by employing transmission electron microscopy, Kelvin probe force microscopy and other methods. It was found that sigma precipitates appeared at the grain boundaries of the alloy being sensitized. There was a Cr-depleted zone and a low-potential zone around these precipitates. The potential difference between the sigma precipitates and the low-potential zone was 102 mV, and this increased with the growth of the sigma precipitates. At this potential difference, the migration of the vacancies in the passive film accelerated significantly, and then the protectiveness of the passive film decreased. The intergranular corrosion mechanism of the steel has also be discussed. Full article

(This article belongs to the Special Issue Investigation on Structure and Corrosion Resistance of Steels/Alloys)

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Open AccessArticle

Study on the Galvanic Corrosion between 13Cr Alloy Tubing and Downhole Tools of 9Cr and P110: Experimental Investigation and Numerical Simulation

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Coatings 2023, 13(5), 861; https://doi.org/10.3390/coatings13050861 - 30 Apr 2023

Cited by 1 | Viewed by 794

Abstract

The galvanic corrosion of oil and gas production string is related to wellbore integrity and production safety. In order to study the galvanic corrosion of an oil and gas well tubing assembly and maintain production safety, this paper studied the galvanic corrosion behavior [...] Read more.

The galvanic corrosion of oil and gas production string is related to wellbore integrity and production safety. In order to study the galvanic corrosion of an oil and gas well tubing assembly and maintain production safety, this paper studied the galvanic corrosion behavior between 13Cr alloy steel tubing and the downhole tools of 9Cr and P110 in formate annular fluid via experimental and numerical simulation methods. The chemical composition, HTHP corrosion tests and electrochemical measurement of the three materials were investigated to analyze the corrosion mechanism and electrochemical parameters. Then, a full-sized 3D galvanic corrosion model of 13Cr tubing and a 9Cr/P110 joint combination was established using COMSOL Multiphysics software based on the electrochemical test results. The mechanism and current variation law of the galvanic corrosion of different tubing materials are discussed and analyzed in the paper. The results revealed that the corrosion rates obtained based on the electrochemical test are as follows: P110 (0.072 mm/y) > 9Cr (0.033 mm/y) > 13Cr (0.0022 mm/y). The current densities of a combination of 13Cr tubing with a 9Cr joint and 13Cr tubing with a P110 joint vary dramatically: the current density of the 13Cr tubing–P110 joint reach 1.6 × 10⁻⁴ A/cm², higher than the current density of the combination of 13Cr tubing and a 9Cr joint. The results of a 3D FEM analysis show that the 13Cr tube demonstrates obvious galvanic corrosion with 9Cr and P110 joints, which is consistent with the analysis results of the polarization curve. This study therefore explains the galvanic corrosion mechanism of different tubing materials and provides guidance for the safe use of tubing in the productive process. Full article

(This article belongs to the Special Issue Investigation on Structure and Corrosion Resistance of Steels/Alloys)

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Open AccessArticle

Convolvulus microphyllus Extract as a Green, Effective, and Affordable Corrosion Inhibitor: Theoretical Calculations and Experimental Studies

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Coatings 2023, 13(5), 860; https://doi.org/10.3390/coatings13050860 - 30 Apr 2023

Cited by 1 | Viewed by 1060

Abstract

This study demonstrates the ability of Convolvulus microphyllus extract to prevent low-carbon steel corrosion (LCS) by varying inhibitor concentration. The effectiveness of the corrosion reaction was examined using gravimetric techniques and electrochemical procedures in a corrosive 0.5 M sulfuric acid medium. The results [...] Read more.

This study demonstrates the ability of Convolvulus microphyllus extract to prevent low-carbon steel corrosion (LCS) by varying inhibitor concentration. The effectiveness of the corrosion reaction was examined using gravimetric techniques and electrochemical procedures in a corrosive 0.5 M sulfuric acid medium. The results of polarization show a mixed adsorption nature on the LCS surface. C. microphyllus-derived film (extract) had an inhibition efficiency (IE) of 92.47% at an inhibitor concentration of 600 mg/L and a temperature 298 K. To examine the morphology, a scanning electron microscope (SEM) and atomic force microscope (AFM) were used to analyze the external films that protect LCS from sulfuric acid. A thin protective coat of inhibitor outside the LCS substrate follows the Langmuir adsorption isotherm. Additionally, computational exploration provided vital insights. The results of these experimental inhibitory outcomes are consistent with those of molecular dynamic simulations. Full article

(This article belongs to the Special Issue Investigation on Structure and Corrosion Resistance of Steels/Alloys)

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Open AccessArticle

Corrosion Behaviors of N80 and 1Cr Tubing Steels in CO₂ Containing Downhole Environment—A Case Study of Underground Gas Storage in LiaoHe Oil Field

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Coatings 2023, 13(4), 737; https://doi.org/10.3390/coatings13040737 - 04 Apr 2023

Viewed by 767

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Investigation on Structure and Corrosion Resistance of Steels/Alloys)

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Open AccessArticle

Improved Corrosion Resistance Behaviour of AlSi10Mg Alloy due to Selective Laser Melting

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Abhishek Tiwari

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Gaurav Singh

and

Rengaswamy Jayaganthan

Coatings 2023, 13(2), 225; https://doi.org/10.3390/coatings13020225 - 18 Jan 2023

Viewed by 1315

Abstract

The corrosion behaviour of AlSi10Mg alloy produced by selective laser melting (SLM) under two different atmospheres, namely argon and nitrogen, was compared to that of AlSi10Mg alloy that had been cast. The present study demonstrates the systematic electrochemical behaviour of selective-laser-melted (SLMed) AlSi10Mg. [...] Read more.

The corrosion behaviour of AlSi10Mg alloy produced by selective laser melting (SLM) under two different atmospheres, namely argon and nitrogen, was compared to that of AlSi10Mg alloy that had been cast. The present study demonstrates the systematic electrochemical behaviour of selective-laser-melted (SLMed) AlSi10Mg. Potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical behaviour, illustrating the degrading features of SLMed AlSi10Mg alloy in 0.1 M NaCl solution. The corrosion resistance of AlSi10Mg produced using selective laser melting was found to be 2–3 times greater than that of AlSi10Mg that had been cast. The degradation behaviour was also explained by SEM analysis of the corroded samples of SLMed AlSi10Mg and as-cast AlSi10Mg alloy. It may be deduced that the better corrosion resistance of AlSi10Mg produced through selective laser melting is due to the fast cooling rate associated with the solidification of AlSi10Mg alloy fabricated through selective laser melting, compared with the slow cooling rate associated with the solidification of AlSi10Mg produced by casting. Full article

(This article belongs to the Special Issue Investigation on Structure and Corrosion Resistance of Steels/Alloys)

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Open AccessArticle

Effect of Sigma Phases on Moderate-Temperature Tensile Properties of Z3CN20.09M CASS Used for Primary Coolant Pipe of Nuclear Power Plant

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Coatings 2023, 13(1), 101; https://doi.org/10.3390/coatings13010101 - 05 Jan 2023

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Abstract

The effect of sigma phases on the moderate-temperature tensile properties of Z3CN20.09M casting austenite stainless steel was investigated by means of isothermal treatment, scanning electron microscopy, transmission electron microscopy, instrumented nanoindentation, tensile testing, and finite element simulation. The results show that the yield [...] Read more.

The effect of sigma phases on the moderate-temperature tensile properties of Z3CN20.09M casting austenite stainless steel was investigated by means of isothermal treatment, scanning electron microscopy, transmission electron microscopy, instrumented nanoindentation, tensile testing, and finite element simulation. The results show that the yield strength and ultimate tensile strength of aged specimens tensile tested at moderate temperature increase remarkably with an increasing sigma phase, while the elongation at break decreased. The strain-hardening rate of aged specimens with sigma phases is higher than that of unaged specimens without sigma phases at a certain low-strain range. However, the value of the strain-hardening rate of aged specimens is lower than that of unaged specimens when the strain exceeds a certain value. The effect of the sigma phase on the tensile properties at moderate temperature is also more significant. This can be attributed to the many high-energy σ/γ₂ and α/σ/γ₂ incoherent phase boundaries caused by the precipitation of sigma phases. On the one hand, these boundaries hinder the movement of dislocations and subsequently accumulate dislocations to some extent, so strength is enhanced and the strain-hardening rate is improved. On the other hand, microcracks at these interfaces initiate and propagate more easily when the strain exceeds a certain value. Thus, the elongation value and the strain-hardening rate decrease. Full article

(This article belongs to the Special Issue Investigation on Structure and Corrosion Resistance of Steels/Alloys)

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Open AccessArticle

Preparation of Graphene Conductive Fabrics and the Study of Their Degradation Behavior

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Coatings 2022, 12(10), 1432; https://doi.org/10.3390/coatings12101432 - 29 Sep 2022

Cited by 2 | Viewed by 1010

Abstract

Graphene has excellent electromagnetic, mechanical, thermal, and optical properties and has been widely applied in materials science, biomedicine, physics, energy storage, chemistry, and textile fields all over the world. In this paper, graphene conductive fabrics were prepared by the impregnation method, and ascorbic [...] Read more.

Graphene has excellent electromagnetic, mechanical, thermal, and optical properties and has been widely applied in materials science, biomedicine, physics, energy storage, chemistry, and textile fields all over the world. In this paper, graphene conductive fabrics were prepared by the impregnation method, and ascorbic acid was used as a reducing agent. Ammonia-cotton blended fabric was used as the base material. Results indicated that graphene had been successfully covered on fabrics according to XRD and SEM analysis. The optimum technological parameters for preparing graphene conductive fabrics were: impregnation five times, reduction temperature at 95 °C, the ascorbic acid concentration of 0.06 mol/L, and the reduction time was 40 min. A corrosion study indicated that rGO fabrics could be partly corroded in 3 wt.% NaCl solution, leading to a decrease in resistivity. However, the conductive ability of rGO fabric changed little with time due to the good stability of rGO. Full article

(This article belongs to the Special Issue Investigation on Structure and Corrosion Resistance of Steels/Alloys)

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Open AccessArticle

Effect of Ultrasonic Impact Strengthening on Surface Properties of 316L Stainless Steel Prepared by Laser Selective Melting

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Coatings 2022, 12(9), 1243; https://doi.org/10.3390/coatings12091243 - 25 Aug 2022

Cited by 1 | Viewed by 929

Abstract

In order to study the effect of ultrasonic impact (UIP) on the microstructure and properties of 316L stainless steel prepared by selective laser melting (SLM), the hardness of the surface layer and depth direction of the sample were tested with a micro hardness [...] Read more.

In order to study the effect of ultrasonic impact (UIP) on the microstructure and properties of 316L stainless steel prepared by selective laser melting (SLM), the hardness of the surface layer and depth direction of the sample were tested with a micro hardness tester. Finally, the friction and wear test of the sample was assessed using a friction and wear tester. The electrochemical corrosion test was carried out on the samples before and after the ultrasonic shock using a CHI660E electrochemical workstation. The results show that after the ultrasonic impact on the 316L stainless steel prepared by SLM, the surface produces plastic deformation and work hardening, which improves the hardness of the material surface and enhances the wear resistance of the sample surface. With ultrasound shocks affecting the near surface of the sample, a deformation layer of about 100 μm depth is formed. After the ultrasonic shock treatment, the self -corrosion potential of the sample in the 3.5% NACl solution is slightly higher than the unproofed sample, and the density of the self -corrosion current is also lower than the unproofed sample., indicating that ultrasonic shock can reduce the corrosion rate of the material surface and enhance the abrasion resistance of the sample surface. Full article

(This article belongs to the Special Issue Investigation on Structure and Corrosion Resistance of Steels/Alloys)

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