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14 pages, 25458 KiB

Open AccessArticle

Research on the Chloride Ion Corrosion Resistance of Cu-Sb-Added Low-Carbon Steel

by Yuanyu Chen, Zhengbing Meng, Yuxiang Li and Jialong Shen

Metals 2024, 14(6), 611; https://doi.org/10.3390/met14060611 - 22 May 2024

Viewed by 882

Abstract

The corrosion resistance of low-carbon steel and two new low-alloy, corrosion-resistant steels containing Cu-Sb and Cu was studied in a simulated seawater environment. The effects of Cu and Sb on corrosion resistance were analyzed by an electrochemical test and accelerated corrosion test. The [...] Read more.

The corrosion resistance of low-carbon steel and two new low-alloy, corrosion-resistant steels containing Cu-Sb and Cu was studied in a simulated seawater environment. The effects of Cu and Sb on corrosion resistance were analyzed by an electrochemical test and accelerated corrosion test. The results show that Cu and Sb reduce the corrosion current density by increasing the corrosion potential and increasing the polarization resistance. Sb can promote the formation of Cu-containing compounds with a strong corrosion inhibition performance, and it can enhance the overall corrosion resistance of steel. In addition, Sb can also promote the conversion of Fe²⁺ ions into a corrosion-resistant compound, α-FeOOH, and it also further improves the corrosion resistance of steel. Full article

(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)

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12 pages, 5167 KiB

Open AccessArticle

Effects of Alloying Element on Hydrogen Adsorption and Diffusion on α-Fe(110) Surfaces: First Principles Study

by Luying Zhang, Qingzhe Zhang, Peng Jiang, Ying Liu, Chen Zhao and Yuhang Dong

Metals 2024, 14(5), 487; https://doi.org/10.3390/met14050487 - 23 Apr 2024

Viewed by 1359

Abstract

Based on first principles density functional theory (DFT) methods, this study employed the Cambridge Serial Total Energy Package (CASTEP) module within Materials Studio (MS) software under the generalized gradient approximation to investigate the adsorption, diffusion behavior, and electronic properties of hydrogen atoms on [...] Read more.

Based on first principles density functional theory (DFT) methods, this study employed the Cambridge Serial Total Energy Package (CASTEP) module within Materials Studio (MS) software under the generalized gradient approximation to investigate the adsorption, diffusion behavior, and electronic properties of hydrogen atoms on α-Fe(110) and α-Fe(110)-Me (Mn, Cr, Ni, Mo) surfaces, including calculations of their adsorption energies and density of states (DOS). The results demonstrated that doping with alloy atoms Me increased the physical adsorption energy of H₂ molecules on the surface. Specifically, Mo doping elevated the adsorption energy from −1.00825 eV to −0.70226 eV, with the largest relative change being 30.35%. After doping with Me, the chemical adsorption energy of two hydrogen atoms does not change significantly, among which doping with Cr results in a decrease in the chemical adsorption energy. Building on this, further analysis of the chemical adsorption of single atoms on the surface was conducted. By comparing the adsorption energy and the bond length between a hydrogen atom and iron/dopant metal atom, it was found that Mo doping has the greatest impact, increasing the bond length by 58.58%. Analysis of the DOS functions under different doping conditions validated the interaction between different alloy elements and H atoms. Simultaneously, simulations were carried out on the energy barrier crossed by H atoms diffusing into the metal interior. The results indicate that Ni doping facilitates the diffusion of H atoms, while Cr, Mn, and Mo hinder their diffusion, with Mo having the most significant effect, where its barrier is 21.88 times that of the undoped surface. This conclusion offers deep insights into the impact of different doping elements on hydrogen adsorption and diffusion, aiding in the design of materials resistant to hydrogen embrittlement. Full article

(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)

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20 pages, 2843 KiB

Open AccessArticle

Corrosion of API 5L X60 Pipeline Steel in Soil and Surface Defects Detection by Ultrasonic Analysis

by Fatima Benkhedda, Ismail Bensaid, Abderrahim Benmoussat, Sid Ahmed Benmansour and Abdeldjelil Amara Zenati

Metals 2024, 14(4), 388; https://doi.org/10.3390/met14040388 - 26 Mar 2024

Viewed by 1410

Abstract

The corrosion steels phenomenon is one of the main problems in the oil industry, such as in buried transmission pipelines used for high gas pressure for long distances. Steels are protected from the external soil corrosion through a bituminous coating, whose action is [...] Read more.

The corrosion steels phenomenon is one of the main problems in the oil industry, such as in buried transmission pipelines used for high gas pressure for long distances. Steels are protected from the external soil corrosion through a bituminous coating, whose action is coupled with a cathodic protection system, which aims to maintain steel in its protection field and thus to avoid any corrosion risk. However, steels in service may experience external surface defects like corrosion pitting and cracking due to electrochemical or mechanical interactions of bare steel with an aggressive soil solution after steel protection failure. These are concerning phenomena and are the major threats of the pipeline transmission system’s reliability and ecological safety. Corrosion mechanisms are varied and can be evaluated by different methods, such as electrochemical measurements, which are influenced by various factors like temperature, pH, soil characteristics, resistivity, water content, and as well mechanical stresses. Corrosion results from simulated artificial soil solutions showed that steel is sensitive to corrosion by soil. Surface defects detection was carried out using an ultrasonic non-destructive method such as C-Scan Emission testing and the time of flight diffraction technique (TOFD) ultrasonic non-contact testing method. After propagation of the ultrasonic waves, the diffracted ultrasonic reflected wave occurring at the edges of the defects appears due to the presence of a corrosion defect by generating defect echoes. The C-Scan ultrasonic image shows surface reflection, including corrosion defects on interfaces with varying acoustic impedances. The cross-transverse speed ultrasonic propagation through the plate including defect is modified, revealing more surface defects, and cross-transverse speed is shown to increase ultrasonic detection presents some advantages, such as precision and speed of detection without alteration to the structure. This method can be used in the industrial context as an intelligent industrial robotics technique. Full article

(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)

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13 pages, 3529 KiB

Open AccessArticle

The Formation of Phytic Acid–Silane Films on Cold-Rolled Steel and Corrosion Resistance

by Wanjiao Duan, Yunying Fan, Baipo Shu, Yichun Liu, Yi Wan, Rongguang Xiao, Jianxin Xu, Shan Qing and Qingtai Xiao

Metals 2024, 14(3), 326; https://doi.org/10.3390/met14030326 - 12 Mar 2024

Viewed by 1289

Abstract

In this work, phytic acid (PA) and 3-mercaptopropyltrimethoxysilane (MPTS) underwent a condensation process to produce a phytic acid–silane (abbreviated PAS) passivation solution. Additionally, it was applied to the surface of cold-rolled steel to create a composite phytic acid–silane film. The functional groups of [...] Read more.

In this work, phytic acid (PA) and 3-mercaptopropyltrimethoxysilane (MPTS) underwent a condensation process to produce a phytic acid–silane (abbreviated PAS) passivation solution. Additionally, it was applied to the surface of cold-rolled steel to create a composite phytic acid–silane film. The functional groups of the passivation solution were analyzed by Fourier transform infrared spectroscopy (FT-IR). The composite film was evaluated using an electrochemical workstation, scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS) and pull-off test. These techniques allowed for the characterization of the film’s micromorphology, oxidation, chemical composition and adhesion strength. The results show that the PAS composite film provides higher protection efficiency compared to cold-rolled steel substrates, low phosphorus passivation films, single phytate passivation films and commercial phosphate films. This composite film also has a higher adhesion strength, which is beneficial for subsequent coating, and a possible corrosion resistance mechanism was proposed as well. The PAS layer successfully prevents the penetration of corrosive media into the cold-rolled steel surface utilizing P–O–Fe bonds, thus improving the corrosion barrier effect of the substrate. Full article

(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)

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14 pages, 4174 KiB

Open AccessArticle

Corrosion Performance of Fe-Based Amorphous Coatings via Laser Cladding Assisted with Ultrasonic in a Simulated Marine Environment

by Huawei Han, Mingying Xiao and Qichen Wang

Metals 2023, 13(12), 1938; https://doi.org/10.3390/met13121938 - 27 Nov 2023

Cited by 3 | Viewed by 1360

Abstract

Fe-based amorphous alloys are considered potential coating materials for applications in marine corrosive environments owing to their high resistance to chloride ion corrosion. Fe-based amorphous alloy (Fe₄₁Co₇Cr₁₅Mo₁₄C₁₅B₆Y₂) was deposited [...] Read more.

Fe-based amorphous alloys are considered potential coating materials for applications in marine corrosive environments owing to their high resistance to chloride ion corrosion. Fe-based amorphous alloy (Fe₄₁Co₇Cr₁₅Mo₁₄C₁₅B₆Y₂) was deposited on AISI 1020 steel using ultrasonic-assisted laser cladding. The research findings revealed a gradient structure generated at the junction of the coating and substrate. Ultrasonic promoted crystallization and increased the gradient structure’s average thickness, reducing coating surface cracks. However, ultrasonic had little effect on the amorphous content of the prepared coating surface, which still had a high amorphous content. The Fe-based amorphous coating prepared via laser cladding with ultrasonic demonstrated good corrosion resistance. The corrosion resistance of the coating without ultrasonic was reduced significantly due to cracks. EIS results confirmed that corrosion resistance was related to crystallization and crack issues. Cr element segregation due to crystallization hindered passivation film forming, reducing its corrosion resistance. Crack corrosion enlarged the crack gap and hollowed out the coating and the substrate’s binding zone, accelerating coating failure. Full article

(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)

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16 pages, 13291 KiB

Open AccessArticle

High-Temperature Oxidation of Boiler Steels at 650 °C

by Jaka Burja, Barbara Šetina Batič, Borut Žužek and Tilen Balaško

Metals 2023, 13(11), 1887; https://doi.org/10.3390/met13111887 - 13 Nov 2023

Viewed by 1369

Abstract

This study presents a comprehensive investigation of the formation, composition and behaviour of oxide layers during the high-temperature oxidation of four different steel alloys (16Mo3, 13Cr, T24 and P91) at a uniform temperature of 650 °C. The study is aimed at assessing the [...] Read more.

This study presents a comprehensive investigation of the formation, composition and behaviour of oxide layers during the high-temperature oxidation of four different steel alloys (16Mo3, 13Cr, T24 and P91) at a uniform temperature of 650 °C. The study is aimed at assessing the oxidation damage due to short-term overheating. The research combines CALPHAD (CALculation of PHAse Diagrams) calculations, thermogravimetric analysis (TGA) and advanced microscopy techniques, including scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), to elucidate the complex mechanisms controlling oxidation kinetics and oxide layer development. CALPHAD calculations were used to determine the thermodynamically stable phases for each steel type at 650 °C and different oxygen activities. The results showed different phase compositions, highlighting the importance of the chromium content in steel for the formation of oxide layers. The different oxidation kinetics and oxide layer compositions are presented and associated with the increased risk of material degradation due to overheating. These results have significant implications for industrial applications, mainly the susceptibility to oxidation of low-alloyed steels like 16Mo3 and 13 Cr and contribute to a deeper understanding of oxidation processes in steels. Full article

(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)

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15 pages, 15602 KiB

Open AccessFeature PaperArticle

Crack Initiation in Ni-Based Single Crystal Superalloy under Low-Cycle Fatigue-Oxidation Conditions

by Pengfei Wang, Xinbao Zhao, Quanzhao Yue, Wanshun Xia, Qingqing Ding, Hongbin Bei, Yuefeng Gu and Ze Zhang

Metals 2023, 13(11), 1878; https://doi.org/10.3390/met13111878 - 11 Nov 2023

Cited by 2 | Viewed by 1431

Abstract

The mechanism of oxidation-assisted initiation of surface cracks of a fourth-generation Ni-based single crystal superalloy was systematically investigated during low cycle fatigue at 900 °C and 980 °C. The results show that cracks initiate near the surface defects at 900 °C, while they [...] Read more.

The mechanism of oxidation-assisted initiation of surface cracks of a fourth-generation Ni-based single crystal superalloy was systematically investigated during low cycle fatigue at 900 °C and 980 °C. The results show that cracks initiate near the surface defects at 900 °C, while they initiate in the surface oxide layer at 980 °C. At 900 °C, the oxidation microcrack initiation in the thicker inner oxidation layer is difficult to connect with the surface oxidation crack, which is an essential reason for the crack growth rate being slower and not becoming the main crack. At 980 °C, microcracks form in the outer oxide layer and quickly connect with microcracks at the surface and inner/outer oxide layer interface, growing into long cracks that become channels for rapid oxygen transport. This accelerates the crack growth rate, and eventually the oxide crack becomes the main crack. Full article

(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)

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16 pages, 20662 KiB

Open AccessArticle

Precipitation Behavior and Corrosion Properties of Stirred Zone in FSWed AA5083 Al-Mg Alloy after Sensitization

by Wenbin Gao, Jiaao Ning, Xiaoyan Gu, Liangyu Chen, Hang Liang, Wenhang Li and John J. Lewandowski

Metals 2023, 13(9), 1618; https://doi.org/10.3390/met13091618 - 19 Sep 2023

Cited by 3 | Viewed by 1208

Abstract

This paper investigated the Mg-rich phase precipitation behavior and the corrosion performance throughout the thickness direction within the stirred zone (SZ) of friction stir welded (FSW) AA5083 alloy after 175 °C/100 h sensitization. For the as-welded SZ, the recrystallized grain size gradually decreased [...] Read more.

This paper investigated the Mg-rich phase precipitation behavior and the corrosion performance throughout the thickness direction within the stirred zone (SZ) of friction stir welded (FSW) AA5083 alloy after 175 °C/100 h sensitization. For the as-welded SZ, the recrystallized grain size gradually decreased from the top surface (5.5 μm) to the bottom (3.7 μm). The top and bottom of the SZ maintained relatively high levels of deformed grains and accumulated strain induced by either shoulder pressing or pin stirring. After 175 °C/100 h sensitization, 100 nm thick β′-Al₃Mg₂ precipitates were present along the grain boundaries (GBs) in the SZ. The bottom of the SZ exhibited more continuous precipitates along GBs due to the fine grain size and the large fraction of high-angle grain boundaries (0.724%). Although the as-welded SZ exhibited excellent corrosion resistance, it became extremely vulnerable to intergranular cracking (IGC) and stress corrosion cracking (SCC) after sensitization. The large SCC susceptibility indices of the SZ samples ranged from 66.9% to 73.1%. These findings suggest that sensitization can strongly deteriorate the corrosion resistance of the Al-Mg FSW joint, which is of critical importance for the safety and reliability of marine applications. Full article

(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)

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11 pages, 4338 KiB

Open AccessArticle

Hydrogen Embrittlement Behavior of a Commercial QP980 Steel

by Linlin Zhao, Cheng Ma, Aimin Zhao, Yuheng Fan and Zhiqiang Li

Metals 2023, 13(8), 1469; https://doi.org/10.3390/met13081469 - 15 Aug 2023

Cited by 5 | Viewed by 1325

Abstract

The hydrogen embrittlement (HE) behavior of a commercial QP980 steel is studied in this work. The HE susceptibility results indicate that QP980 suffers from a severe HE, and the fracture mode transforms from ductile dimpling to brittle quasi-cleavage under the attack of hydrogen. [...] Read more.

The hydrogen embrittlement (HE) behavior of a commercial QP980 steel is studied in this work. The HE susceptibility results indicate that QP980 suffers from a severe HE, and the fracture mode transforms from ductile dimpling to brittle quasi-cleavage under the attack of hydrogen. The EBSD results show that strain-induced martensite transformation can rarely occur at a strain close to the HE fracture strain, which is mainly attributed to the high mechanical stability of austenite. The TKD-KAM analysis results indicate that hydrogen-induced strain localization in martensite can be mitigated by the hydrogen-trapping effect of surrounding austenite, while it is most pronounced in martensite adjacent to ferrite. Correspondingly, HE cracking is considered to initiate in martensite adjacent to ferrite under the synergistic action of HELP and HEDE mechanisms, and then cracks can propagate through ferrite or along phase interfaces. Our findings suggest that to further improve the HE resistance of QP steel with stable austenite, it is necessary to consider introducing effective hydrogen-trapping sites (such as carbides, film austenite) into martensite, which is deemed to be beneficial for increasing the resistance against hydrogen-induced cracking initiation in martensite. Full article

(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)

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13 pages, 7328 KiB

Open AccessArticle

Study on the Microscopic Mechanism of Axle Steel EA4T during Uniaxial Cyclic Deformation Process

by Xuehong Ren, Shaopu Yang, Wenjie Zhao and Guilin Wen

Metals 2023, 13(8), 1379; https://doi.org/10.3390/met13081379 - 31 Jul 2023

Cited by 1 | Viewed by 875

Abstract

In order to reveal the dislocation evolution law of body-centered cubic axle steel EA4T during cyclic deformation and provide an experimental basis for the subsequent construction of cyclic constitutive models based on microscopic physical mechanisms, macroscopic deformation experiments were first conducted on axle [...] Read more.

In order to reveal the dislocation evolution law of body-centered cubic axle steel EA4T during cyclic deformation and provide an experimental basis for the subsequent construction of cyclic constitutive models based on microscopic physical mechanisms, macroscopic deformation experiments were first conducted on axle steel EA4T, including monotonic tensile experiments under different deformation amounts, symmetric strain cycling experiments under a different number of cycles, and ratcheting deformation experiments under a different number of cycles. Then, systematic observations of different samples at different deformation stages were conducted using a Transmission Electron Microscope (TEM) to investigate the dislocation configuration and evolution during strain cycling and ratcheting deformation. The observed results show that the dislocation evolution law of axle steel EA4T during the uniaxial tensile experiment, symmetrical strain cycling, and ratcheting deformation is basically the same, and the dislocation density increases with the increase in plastic deformation and number of cycles. The dislocation configuration gradually develops from low-density dislocation configurations such as dislocation lines and dislocation pileups to high-density dislocation configurations such as severe dislocation tangles and dislocation walls. The microscopic mechanism of the uniaxial ratcheting evolution of axle steel EA4T can be qualitatively explained by the dislocation configuration and evolution. Full article

(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)

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15 pages, 3928 KiB

Open AccessArticle

CO₂ Corrosion Behavior of X70 Steel under Typical Gas–Liquid Intermittent Flow

by Qiang Li, Wenguang Jia, Kaixiang Yang, Wenfeng Dong and Bingcheng Liu

Metals 2023, 13(7), 1239; https://doi.org/10.3390/met13071239 - 5 Jul 2023

Cited by 3 | Viewed by 1326

Abstract

Gas–liquid intermittent flow is a kind of flow pattern that distinguishes itself from the conventional flow by the apparent non-steady feature, which causes serious corrosion issues, including localized corrosion. Although it widely exists in wet gas pipelines, how the gas–liquid intermittent flow influences [...] Read more.

Gas–liquid intermittent flow is a kind of flow pattern that distinguishes itself from the conventional flow by the apparent non-steady feature, which causes serious corrosion issues, including localized corrosion. Although it widely exists in wet gas pipelines, how the gas–liquid intermittent flow influences CO₂ corrosion of pipeline steels remains a problem to be clarified. In this work, a testing device that enables good simulation of gas–liquid intermittent flow in wet gas pipelines under various conditions was developed and used to perform experimental studies, combining electrochemical tests and corrosion morphology observations. The result shows that flow velocity and gas–liquid ratio act together to affect the CO₂ corrosion behavior of X70 steel in typical intermittent flow conditions. The flow velocity has a more profound effect on the corrosion rate, while the gas–liquid ratio is associated with the occurrence of localized corrosion. The effect of the gas–liquid ratio on corrosion behavior was discussed. Full article

(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)

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21 pages, 4877 KiB

Open AccessArticle

Corrosion of Metals Modified with Formulations Based on Organosilanes

by Maxim Petrunin, Tatyana Yurasova, Alevtina Rybkina and Liudmila Maksaeva

Metals 2023, 13(4), 721; https://doi.org/10.3390/met13040721 - 6 Apr 2023

Cited by 1 | Viewed by 1719

Abstract

Methods for preliminary modification of the surface of structural metals with formulations based on organosilanes, including both solutions of individual organosilanes and two-component mixtures consisting of two organosilanes or an organosilane with an organic corrosion inhibitor, have been developed. As a result of [...] Read more.

Methods for preliminary modification of the surface of structural metals with formulations based on organosilanes, including both solutions of individual organosilanes and two-component mixtures consisting of two organosilanes or an organosilane with an organic corrosion inhibitor, have been developed. As a result of this modification, a self-assembling siloxane polymeric/oligomeric nanoscale layer is formed on the metal surface. Such layers are capable of changing the physicochemical properties of the metal surface, in particular reducing the susceptibility of the metal to corrosive destruction. In this work, the mechanism of formation of organosilicon nanolayers and their effect on the electrochemical and corrosion behavior of metals have been studied in detail by a set of electrochemical methods, while laboratory studies and accelerated corrosion tests of carbon steel and zinc, modified with formulations based on organosilanes, have been carried out. The greatest inhibitory effect is demonstrated by two-component modifying formulations, namely mixtures of vinyl with aminosilane and vinylsilane with benzotriazole. The mechanism of corrosion inhibition by surface nanolayers formed upon surface modification with two-component mixtures has been considered. Full article

(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)

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12 pages, 4350 KiB

Open AccessArticle

The Formation Mechanism of a Multilayer-Structure Oxide Film during the Oxidation of FeCrAl in Air at 700 °C

by Zichen Gao, Xinyu Wang, Danna Zhou, Qingsheng Wu, Chunjing Li, Liangliang Song and Shaojun Liu

Metals 2023, 13(2), 305; https://doi.org/10.3390/met13020305 - 2 Feb 2023

Cited by 1 | Viewed by 1595

Abstract

A protective oxide film is the key to the corrosion resistance of the FeCrAl alloy. The mechanism of the formation of the multilayer oxide film of the FeCrAl alloy in 700 °C air was explored by studying the structure evolution of the oxide [...] Read more.

A protective oxide film is the key to the corrosion resistance of the FeCrAl alloy. The mechanism of the formation of the multilayer oxide film of the FeCrAl alloy in 700 °C air was explored by studying the structure evolution of the oxide film and the oxidation kinetics of FeCrAl. The results show that a multilayer oxide layer is formed on the surface of the FeCrAl alloy after 1344 h, with a (Fe,Cr)₂O₃ layer, an Al-rich oxide layer, an Al-depleted zone, and a new Al-rich oxide layer sequentially arranged from the surface to the matrix. This indicates that the Al element plays an important role in the formation of the oxide film. The Al in the matrix is depleted to form the Al-rich oxide layer, resulting in the Al-depleted zone. The new Al-rich oxide layer is formed under the Al-depleted zone by internal oxidation. It should be noted that the precipitation of the AlN phase in the matrix is observed, which might be a probable factor for the Al-depleted zone in the matrix. Full article

(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)

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37 pages, 17666 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Effect of σ-Phase on the Strength, Stress Relaxation Behavior, and Corrosion Resistance of an Ultrafine-Grained Austenitic Steel AISI 321

by Vladimir I. Kopylov, Aleksey V. Nokhrin, Natalia A. Kozlova, Mikhail K. Chegurov, Mikhail Yu. Gryaznov, Sergey V. Shotin, Nikolay V. Melekhin, Nataliya Yu. Tabachkova, Ksenia E. Smetanina and Vladimir N. Chuvil’deev

Metals 2023, 13(1), 45; https://doi.org/10.3390/met13010045 - 24 Dec 2022

Cited by 6 | Viewed by 2985

Abstract

This paper reported the results of research into the effect of Equal Channel Angular Pressing (ECAP) temperature and 1-h annealing temperature on mechanical properties, stress-relaxation resistance, and corrosion resistance of austenitic steel AISI 321L with strongly elongated thin δ-ferrite particles in its microstructure. [...] Read more.

This paper reported the results of research into the effect of Equal Channel Angular Pressing (ECAP) temperature and 1-h annealing temperature on mechanical properties, stress-relaxation resistance, and corrosion resistance of austenitic steel AISI 321L with strongly elongated thin δ-ferrite particles in its microstructure. The formation of α′-martensite and fragmentation of austenite grains takes place during ECAP. Ultrafine-grained (UFG) steels demonstrate increased strength. However, we observed a reduced Hall–Petch coefficient as compared with coarse-grained (CG) steels due to the fragmentation of δ-ferrite particles. UFG steel specimens were found to have 2–3 times higher stress-relaxation resistance as compared with CG steels. For the first time, the high stress-relaxation resistance of UFG steels was shown to stem from a internal stress-relaxation mechanism, i.e., the interaction of lattice dislocations with non-equilibrium grain boundaries. Short-time 1-h annealing of UFG steel specimens at 600–800 °C was found to result in the nucleation of σ-phase nanoparticles. These nanoparticles affect the grain boundary migration, raise strength, and stress-relaxation resistance of steel but reduce the corrosion resistance of UFG steel. Lower corrosion resistance of UFG steel was shown to be related to the formation of α′-martensite during ECAP and the nucleation of σ-phase particles during annealing. Full article

(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)

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Review

Jump to: Research

17 pages, 2961 KiB

Open AccessReview

Review of Characterization on Hydrogen Embrittlement by Micro-Sample Testing Methods

by Ping Tao, Wei Zhou, Xinting Miao, Jian Peng and Wenming Liu

Metals 2023, 13(10), 1753; https://doi.org/10.3390/met13101753 - 16 Oct 2023

Cited by 3 | Viewed by 2390

Abstract

Conventional-sized specimens have been well and widely applied in research on hydrogen embrittlement. However, when the limited-size core components (nozzles and valves, etc.) of hydrogen energy equipment are evaluated for service damage, traditional testing with conventional-sized samples is no longer applicable and micro-sample [...] Read more.

Conventional-sized specimens have been well and widely applied in research on hydrogen embrittlement. However, when the limited-size core components (nozzles and valves, etc.) of hydrogen energy equipment are evaluated for service damage, traditional testing with conventional-sized samples is no longer applicable and micro-sample testing methods are required. In this paper, recent progress in the characterization of hydrogen embrittlement achieved via a small-sized sample tensile test, small punch test and nanoindentation test is reviewed. The commonly used geometries and dimensions of various small-sized specimens are first described and the in situ hydrogen-containing environment testing cases equipped with small-sized specimens are presented, proving the advantages of direct observations of hydrogen influences on the mechanical property and microstructure evolution. Then, the quantitative analysis of hydrogen embrittlement sensitivity involving a small punch test is discussed, with a focus on the comparisons of the hydrogen embrittlement index calculated using different definition methods. Finally, the nanoindentation test of investigation on the interaction between hydrogen and dislocation in metals and the effect of indentation strain rate are summarized. Furthermore, the specific research directions and applications of micro-size specimens for further investigation on hydrogen embrittlement are identified. Full article

(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)

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