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21 pages, 5645 KiB  
Article
Effect of Heat Treatment on the Corrosion Behavior of Weld-Deposited Chromium Carbide-Based Hardfacing Alloys
by Cedric Tan, Kannoorpatti Krishnan and Naveen Kumar Elumalai
Metals 2024, 14(12), 1436; https://doi.org/10.3390/met14121436 - 14 Dec 2024
Viewed by 264
Abstract
The effects of heat treatment on the microstructure and corrosion behavior of chromium carbide-based hardfacing alloys deposited via gas metal arc welding were investigated. The hardfacing alloy, high chromium white iron (HCWI), containing 27 wt% Cr and 4.8 wt% C, was heat treated [...] Read more.
The effects of heat treatment on the microstructure and corrosion behavior of chromium carbide-based hardfacing alloys deposited via gas metal arc welding were investigated. The hardfacing alloy, high chromium white iron (HCWI), containing 27 wt% Cr and 4.8 wt% C, was heat treated at 650 °C and 950 °C for six hours followed by natural cooling to room temperature. Microstructural characterization revealed that heat treatment promoted the transformation of austenite to ferrite and increased carbide precipitation. X-ray diffraction analysis identified the primary carbides as Cr7C3, which remained stable during heat treatment. Electrochemical corrosion testing in artificial seawater, including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), demonstrated progressively improved corrosion resistance with heat treatment temperature. Both techniques confirmed that the specimen treated at 950 °C exhibited superior corrosion resistance compared to the 650 °C treatment and as-deposited condition, with the specimen treated at 950 °C exhibiting the highest charge transfer resistance (4711 Ω·cm2) compared to the 650 °C treatment (2608 Ω·cm2) and as-deposited condition (374.6 Ω·cm2). The enhanced corrosion resistance was attributed to the increased carbide precipitation and optimization of the matrix composition. While heat treatment at both temperatures improved corrosion performance, the 950 °C treatment yielded superior results, suggesting this could be an optimal temperature for enhancing the corrosion resistance of chromium carbide-based hardfacing alloys. Full article
(This article belongs to the Special Issue Recent Advances in Corrosion and Protection of Metallic Materials)
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<p>As-deposited Surface of Alloy H0 for (<b>a</b>) 3000× magnification and (<b>b</b>) 6000× magnification, showing the 1. primary carbide, 2. eutectic austenite, and 3. eutectic carbides.</p>
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<p>Surface of Alloy H650 for (<b>a</b>) 3000× magnification (<b>b</b>) 6000× magnification.</p>
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<p>As-deposited Surface of Alloy H950 for (<b>a</b>) 3000× magnification and (<b>b</b>) 6000× magnification.</p>
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<p>Hardness values for carbides and eutectic carbide/matrix mix.</p>
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<p>XRD for H0, H650, and H950 Cu radiation.</p>
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<p>Potentiodynamic curves for Samples H0, H650, and H950.</p>
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<p>Potentiostatic schematic points as illustrated for Sample H0.</p>
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<p>SEM imagery for Sample H0 at (<b>a</b>) −330 mV, (<b>b</b>) 800 mV, and (<b>c</b>) 1100 mV.</p>
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<p>SEM Imagery for Sample H650 at (<b>a</b>) −330 mV, (<b>b</b>) 800 mV, and (<b>c</b>) 1100 mV.</p>
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<p>SEM imagery for Sample H950 at (<b>a</b>) −330 mV, (<b>b</b>) 800 mV, and (<b>c</b>) 1100 mV.</p>
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<p>Nyquist plot for Samples H0, H650, and H950.</p>
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<p>Bode plot with respect to the phase angle.</p>
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<p>Bode plot with respect to the magnitude.</p>
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<p>Schematic of the expected EIS coating model.</p>
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30 pages, 2254 KiB  
Article
From Pairwise Comparisons of Complex Behavior to an Overall Performance Rank: A Novel Alloy Design Strategy
by Rafael Herschberg, Lisa Rateau, Laure Martinelli, Fanny Balbaud-Célérier, Jean Dhers, Anna Fraczkiewicz, Gérard Ramstein and Franck Tancret
Metals 2024, 14(12), 1412; https://doi.org/10.3390/met14121412 - 10 Dec 2024
Viewed by 510
Abstract
A method is developed to exploit data on complex materials behaviors that are impossible to tackle by conventional machine learning tools. A pairwise comparison algorithm is used to assess a particular property among a group of different alloys tested simultaneously in identical conditions. [...] Read more.
A method is developed to exploit data on complex materials behaviors that are impossible to tackle by conventional machine learning tools. A pairwise comparison algorithm is used to assess a particular property among a group of different alloys tested simultaneously in identical conditions. Even though such characteristics can be evaluated differently across teams, if a series of the same alloys are analyzed among two or more studies, it is feasible to infer an overall ranking among materials. The obtained ranking is later fitted with respect to the alloy’s composition by a Gaussian process. The predictive power of the method is demonstrated in the case of the resistance of metallic materials to molten salt corrosion and wear. In this case, the method is applied to the design of wear-resistant hard-facing alloys by also associating it with a combinatorial optimization of their composition by a multi-objective genetic algorithm. New alloys are selected and fabricated, and their experimental behavior is compared to that of concurrent materials. This generic method can therefore be applied to model other complex material properties—such as environmental resistance, contact properties, or processability—and to design alloys with improved performance. Full article
(This article belongs to the Special Issue Alloy Design and Its Performance Trade-Offs)
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<p>Graphical representation of the pairwise comparisons between the alloys studied in the literature (blue: Ni-based alloys, black: ferritic-martensitic steels, green: BCC HEA, red: FCC HEAs, yellow: austenitic stainless steels (SS), pink: Co-based alloys). The size of nodes is proportional to their centrality degree. Nodes labeled A1 to A5 represent some reference alloys, i.e., those that have been compared the most (see <a href="#metals-14-01412-t002" class="html-table">Table 2</a>).</p>
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<p>Overall alloy rank analyzed in molten salt corrosion experiments. (The complete list of alloys with their chemical composition and individual score <span class="html-italic">S<sub>i</sub></span> can be found in <a href="#app1-metals-14-01412" class="html-app">Appendix A</a> of this manuscript). “Austenitic” stands for “austenitic stainless steels”.</p>
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<p>Comparison between the scores computed by SR and GP. “Austenitic” stands for “austenitic stainless steels”.</p>
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<p>Graphical representation of the pairwise comparisons between the alloys studied in the literature (blue: Ni-based alloys; black: Fe-based alloys; yellow: Co-based alloys). The size of nodes is proportional to their centrality degree. Nodes labeled A and B correspond to Stellite 6 and Norem 02, respectively.</p>
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<p>Rank predicted by the GP regression model as a function of the rank attributed by the pairwise comparison algorithm (SR, see <a href="#app2-metals-14-01412" class="html-app">Appendix B</a>) for the alloys of the database (being either Fe-based, Cot-based, or Ni-based). Stellite 6 and Norem 02 alloys are highlighted.</p>
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<p>Measured specific wear rate as a function of the robust wear rank predicted by the model for reference alloys (Norem 02, Stellite 6, and FeCrB) and the newly designed alloys (AS1, AS2, AS3, and AS4).</p>
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<p>Dependency of the specific wear rate with respect to the free Cr concentration (wt.%).</p>
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17 pages, 4570 KiB  
Article
Comparison of Abrasive Wear Resistance of Hardox Steel and Hadfield Cast Steel
by Martyna Zemlik, Łukasz Konat, Kacper Leśny and Krzysztof Jamroziak
Appl. Sci. 2024, 14(23), 11141; https://doi.org/10.3390/app142311141 - 29 Nov 2024
Viewed by 612
Abstract
Among the materials used for components subjected to abrasive wear, chromium cast iron, hardfaced layers, martensitic steels and Hadfield steel should be singled out. Each of these types of materials exhibits a different morphology of structure and strength properties. Hadfield steel, characterized by [...] Read more.
Among the materials used for components subjected to abrasive wear, chromium cast iron, hardfaced layers, martensitic steels and Hadfield steel should be singled out. Each of these types of materials exhibits a different morphology of structure and strength properties. Hadfield steel, characterized by an austenitic microstructure, shows the ability to strengthen the subsurface layers by cold work, while maintaining a ductile core. Hardox steels belong to the group of low-alloy martensitic boron steels. However, it should be noted that increasing hardness does not always translate into low wear values due to a change in the nature of wear. In view of the above, the authors decided to subject selected Hardox steels and Hadfield cast steels in the post-operational condition to abrasive wear tests in the presence of loose abrasive. The study showed that Hardox Extreme steel exhibits the highest resistance to abrasive wear (value of the coefficient kb is equal to 1.39). In the case of Hadfield steel, the recorded values are slightly lower (kb = 1.32 and 1.33), while the above ratios remain higher compared to Hardox 600 and Hardox 500 steels. The main wear mechanism of high-manganese steels is microploughing, plastic deformation and breakouts of larger fragments of material. In the case of Hardox 450 and Hardox 500 steels, the predominant wear mechanisms are microploughing and breaking out of material fragments. As the hardness of the steel increases, the proportion of wear by microcutting and scratching predominates. Full article
(This article belongs to the Section Surface Sciences and Technology)
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<p>Sample 1. Macroscopic image of the condition of the working surface of the jaw crusher for squashing rocks with a volume of 10–1000 mm. Operating time of about 350 h, throughput of about 80.00 tons.</p>
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<p>Sample 2. Macroscopic image of the surface condition of the ball mill liner plate covering part of the contracture of the chute. Material volume of 100–1200 mm, throughput of about 200.000 tons.</p>
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<p>View and layout of the T-07 tribotester [<a href="#B41-applsci-14-11141" class="html-bibr">41</a>].</p>
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<p>Microstructure of the analyzed wear-resistant materials. In the case of high-manganese cast steels (<b>a</b>,<b>b</b>), a microstructure of coarse-grained austenite with precipitations of intermetallic phases within and at grain boundaries is observed. The discontinuity of the structure—interdendritic gaps—is also characteristic. In the case of Hardox (<b>c</b>–<b>f</b>) steels, a microstructure consisting of fine lath tempering martensite with areas of hardening (fresh) martensite is observed. PAG—prior austenite grain boundary, FM—fresh martensite. Light microscopy, etched with Mi1Fe.</p>
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<p>The value of the coefficient <span class="html-italic">k<sub>b</sub></span> and the results of hardness measurements of the analyzed metallic materials. C45 (N)—C45 steel in as-normalized condition with a hardness of 220 HBW.</p>
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<p>Surfaces subjected to wear testing: (<b>a</b>) sample 1 (GX120MnCr17-2); (<b>b</b>) sample 2 (L120G13T); (<b>c</b>) Hardox 450; (<b>d</b>) Hardox 500; (<b>e</b>) Hardox 600; (<b>f</b>) Hardox Extreme. Electron microscopy, unetched.</p>
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<p>Microstructure of the subsurface area of specimens subjected to wear tests in the direction transverse to the abrasive movement: (<b>a</b>) sample 1 (GX120MnCr17-2); (<b>b</b>) sample 2 (L120G13T); (<b>c</b>) Hardox 450; (<b>d</b>) Hardox 500; (<b>e</b>) Hardox 600; (<b>f</b>) Hardox Extreme. Electron microscopy, etched with Mi1Fe.</p>
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<p>Coefficient of relative abrasion wear resistance <span class="html-italic">k<sub>b</sub></span> and results of hardness measurements of selected low-alloyed martensitic steels. HT-heat-treated. Based on the results presented in this paper and [<a href="#B33-applsci-14-11141" class="html-bibr">33</a>,<a href="#B41-applsci-14-11141" class="html-bibr">41</a>,<a href="#B43-applsci-14-11141" class="html-bibr">43</a>].</p>
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<p>Resistance to abrasive wear in medium abrasive soil mass over the friction path of 20 km and results of hardness measurements of selected low-alloyed martensitic steels. HT-heat-treated. Based on [<a href="#B52-applsci-14-11141" class="html-bibr">52</a>,<a href="#B53-applsci-14-11141" class="html-bibr">53</a>,<a href="#B54-applsci-14-11141" class="html-bibr">54</a>,<a href="#B55-applsci-14-11141" class="html-bibr">55</a>,<a href="#B56-applsci-14-11141" class="html-bibr">56</a>].</p>
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28 pages, 6905 KiB  
Article
Corrosion Behaviour of Heat-Treated Cold Spray Nickel Chromium/Chromium Carbides
by Cedric Tan, Kannoorpatti Krishnan and Naveen Kumar Elumalai
Metals 2024, 14(10), 1153; https://doi.org/10.3390/met14101153 - 10 Oct 2024
Viewed by 699
Abstract
Chromium carbide powder agglomerated with nickel/chrome was deposited using a cold spray process onto a mild steel substrate. The deposits were heat-treated at 650 °C and 950 °C in ambient conditions to reduce porosity and improve adhesion between powder particles. The corrosion behaviour [...] Read more.
Chromium carbide powder agglomerated with nickel/chrome was deposited using a cold spray process onto a mild steel substrate. The deposits were heat-treated at 650 °C and 950 °C in ambient conditions to reduce porosity and improve adhesion between powder particles. The corrosion behaviour of these cold-sprayed materials was studied in artificial seawater conditions using electrochemical techniques. Heat treatment at 650 °C was found to best improve corrosion resistance, while the 950 °C treatment performed better than the as-sprayed condition but lower than the 650 °C sample. Microstructural analysis revealed complex phase transformations and structural refinements with increasing heat treatment temperature. The crystallite size of both Cr3C2 and NiCr phases decreased, while microstrain and dislocation density increased due to heat treatment. The formation of and subsequent reduction in Cr23C6 content indicated a complex sequence of carbide dissolution, transformation, and precipitation processes. The 650 °C heat-treated sample demonstrated superior corrosion resistance, evidenced by the highest corrosion potential, lowest passive current, and largest charge transfer resistance. This enhanced performance was attributed to the formation of a more stable and protective passive film, optimal carbide dissolution, and a homogeneous microstructure. Meanwhile, the 950 °C treatment led to excessive carbide dissolution and formed increased interfaces between the carbide and matrix. Mechanical property changes were also observed, with carbide hardness significantly decreasing after corrosion testing. These findings highlight the critical role of controlled heat treatment in optimising the performance of cold-sprayed Cr3C2-NiCr coatings, demonstrating that achieving superior corrosion resistance requires a delicate balance between microstructural refinement, phase transformations, and preservation of coating integrity. Full article
(This article belongs to the Special Issue Recent Advances in Corrosion and Protection of Metallic Materials)
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<p>Microstructure of Sample A (non-heat-treated) showing primary carbides surrounded by NiCr matrix as well as voids for (<b>a</b>) SEM at lower magnification, (<b>b</b>) SEM at higher magnification, and (<b>c</b>) optical microscopy.</p>
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<p>Microstructure of Sample B heat-treated at 650 °C for (<b>a</b>) SEM at lower magnification, (<b>b</b>) SEM at higher magnification, and (<b>c</b>) optical microscopy.</p>
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<p>Microstructure of Sample C heat-treated at 950 °C for (<b>a</b>) SEM at lower magnification, (<b>b</b>) SEM at higher magnification, and (<b>c</b>) optical microscopy.</p>
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<p>SEM-EDS surface indicating locations of matrix and carbide analysis, with example at 950 °C.</p>
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<p>XRD for 2θ = 40–90°: (<b>a</b>) noHT Sample A, (<b>b</b>) 650HT Sample B, and (<b>c</b>) 950HT Sample C.</p>
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<p>XRD for 2θ = 35–55°: (<b>a</b>) noHT Sample A, (<b>b</b>) 650HT Sample B, and (<b>c</b>) 950HT Sample C.</p>
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<p>Crystallite sizes of Cr<sub>3</sub>C<sub>2</sub> and NiCr.</p>
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<p>Microstrain values of Cr<sub>3</sub>C<sub>2</sub> and NiCr.</p>
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<p>Dislocation densities of Cr<sub>3</sub>C<sub>2</sub> and NiCr.</p>
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<p>EIS Nyquist plot for Samples A, B, and C.</p>
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<p>Bode plots: (<b>a</b>) phase vs. freq and (<b>b</b>) Mod Z vs. freq.</p>
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<p>Equivalent circuit model for the coating system.</p>
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<p>Potentiodynamic curves for Samples A, B, and C.</p>
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<p>Optical microscopy for the noHT Sample A’s potentiostatic point at 45 mV.</p>
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<p>Optical microscopy for the noHT Sample A’s potentiostatic point at 2000 mV.</p>
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<p>Optical microscopy for the 650HT Sample B’s potentiostatic point at 2000 mV.</p>
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<p>Optical microscopy for the 950HT Sample C’s potentiostatic point at 2000 mV.</p>
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<p>Hardness tests for 950HT Sample C (<b>a</b>) before indentation and (<b>b</b>) after indentation. Also note the following features: 1. carbides, 2. collapse of carbide around the indentation, and 3. the square indentation itself.</p>
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<p>Complete removal of carbide post-indentation, as shown surrounded by green box.</p>
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<p>Illustrated microstructural changes with heat treatment.</p>
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18 pages, 8369 KiB  
Article
Surface Integrity of Austenitic Manganese Alloys Hard Layers after Cavitation Erosion
by Ion Mitelea, Ilare Bordeașu, Daniel Mutașcu, Corneliu Marius Crăciunescu and Ion Dragoș Uțu
Lubricants 2024, 12(10), 330; https://doi.org/10.3390/lubricants12100330 - 26 Sep 2024
Viewed by 875
Abstract
Cavitation erosion, as a mechanical effect of destruction, constitutes a complex and critical problem that affects the safety and efficiency of the functioning of engineering components specific to many fields of work, the most well-known being propellers of ships and maritime and river [...] Read more.
Cavitation erosion, as a mechanical effect of destruction, constitutes a complex and critical problem that affects the safety and efficiency of the functioning of engineering components specific to many fields of work, the most well-known being propellers of ships and maritime and river vessels, seawater desalination systems, offshore oil and gas drilling platforms (including drilling and processing equipment), and the rotors and blades of hydraulic machines. The main objective of the research conducted in this paper is to experimentally investigate the phenomenology of this surface degradation process of maritime ships and offshore installations operating in marine and river waters. To reduce cavitation erosion of maritime structures made from Duplex stainless steels, the study used the deposition by welding of layers of metallic alloys with a high capacity for work hardening. The cavitation tests were conducted in accordance with the American Society for Testing and Materials standards. The response of the deposited metal under each coating condition, compared to the base metal, was investigated by calculating the erosion penetration rate (MDER) through mass loss measurements over the cavitation duration and studying the degraded zones using scanning electron microscopy (SEM), the energy-dispersive X-ray analysis, and hardness measurements. It was revealed that welding hardfacing with austenitic manganese alloy contributes to an approximately 8.5–10.5-fold increase in cavitation erosion resistance. The explanation is given by the increase in surface hardness of the coated area, with 2–3 layers of deposited alloy reaching values of 465–490 HV5, significantly exceeding those specific to the base metal, which range from 260–280 HV5. The obtained results highlighted the feasibility of forming hard coatings on Duplex stainless-steel substrates. Full article
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<p>Modification of the crystalline lattice structure through alloying with nickel.</p>
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<p>Dimensions and appearance of the cavitation samples.</p>
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<p>The cavitation equipment: (<b>a</b>)—overview image, 1—sonotrode; 2—electronic system; 3—water temperature regulator; 4—vessel with liquid and cooling coil; 5—ventilation system. (<b>b</b>)—detail of the sample during the cavitation process.</p>
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<p>The specific curves of the mean depth erosion rate: (<b>a</b>)—base metal; (<b>b</b>)—1 deposited layer; (<b>c</b>)—2 deposited layers; (<b>d</b>)—3 deposited.</p>
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<p>The specific curves of the mean depth erosion rate: (<b>a</b>)—base metal; (<b>b</b>)—1 deposited layer; (<b>c</b>)—2 deposited layers; (<b>d</b>)—3 deposited.</p>
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<p>SEM microstructure of the base metal.</p>
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<p>SEM micrograph of the layer-substrate system.</p>
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<p>SEM micrograph (<b>a</b>), EDX spectrum (<b>b</b>), and quantitative analysis values (<b>c</b>) of the first deposited layer.</p>
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<p>The EDX spectrum (<b>a</b>) and quantitative analysis values (<b>b</b>) of the base metal (marked with red square on <a href="#lubricants-12-00330-f005" class="html-fig">Figure 5</a>).</p>
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<p>The SEM micrograph (<b>a</b>), EDX spectrum (<b>b</b>), and quantitative analysis values (<b>c</b>) of the last deposited layer.</p>
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<p>Concentration profiles of the alloying elements on either side of the interface between the deposited metal and the base metal.</p>
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<p>SEM images of the surfaces coated with three layers tested for cavitation for 165 min: (<b>a</b>)–base metal; (<b>b</b>)—hardfacing by welding.</p>
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<p>SEM images of the surfaces coated with three layers tested for cavitation for 165 min: (<b>a</b>)–base metal; (<b>b</b>)—hardfacing by welding.</p>
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17 pages, 20152 KiB  
Article
Extreme High-Speed DED of AISI M2 Steel for Coating Application and Additive Manufacturing
by Min-Uh Ko, Julius Cüppers, Thomas Schopphoven and Constantin Häfner
Coatings 2024, 14(8), 953; https://doi.org/10.3390/coatings14080953 - 31 Jul 2024
Cited by 1 | Viewed by 1005
Abstract
This work focuses on the development of the 3D Extreme High-Speed DED process (EHLA3D), a variant of the laser-based Directed Energy Deposition (DED-LB), for the processing of the material HSS M2. Characteristics for the EHLA3D process are feed rates of >20 m/min, high [...] Read more.
This work focuses on the development of the 3D Extreme High-Speed DED process (EHLA3D), a variant of the laser-based Directed Energy Deposition (DED-LB), for the processing of the material HSS M2. Characteristics for the EHLA3D process are feed rates of >20 m/min, high cooling rates, and layer thicknesses in the range of 100 µm. This work covers the three subsequent stages: (1) a process parameter study on single-track deposition, (2) development of coating parameters, and (3) development of parameters for AM. In scope of stage 2, a coating parameter with a powder mass flow of ṁ = 1.9 kg/h was achieved. A variation in the deposition angles indicates that the coating process is feasible within a tilted deviation of up to 20°. In stage 3, a process parameter with a deposition rate of ṁ = 0.4 kg/h was developed. The hardness results of the as-built specimen with 67 HRC exceeds the hardness of conventionally manufactured and heat-treated M2 steel. The results of this work indicate that the EHLA3D process can be potentially utilized for the additive manufacturing with the material M2 as well as for the productive deposition of anti-wear coatings on free-form surfaces. Full article
(This article belongs to the Special Issue Laser Surface Engineering and Additive Manufacturing)
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<p>Comparison between process set-ups: (<b>a</b>) conventional DED-LB and (<b>b</b>) EHLA [<a href="#B11-coatings-14-00953" class="html-bibr">11</a>].</p>
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<p>EHLA coating process of a brake disk.</p>
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<p>System technology, (<b>a</b>) High-speed 5-axis CNC prototype and (<b>b</b>) machining area with Trumpf Beo D70 processing optics.</p>
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<p>(<b>a</b>) Deposited single tracks with indication of the positions for metallographic cross-sections. (<b>b</b>) Example of a single-track metallographic cross-section with evaluation criteria.</p>
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<p>Path planning for the coating deposition.</p>
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<p>Metallographic cross-section of a coating specimen.</p>
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<p>(<b>a</b>) Collision of processing optics with perpendicular deposition to the surface due to interfering contours. Experimental set-up for the evaluation of the tilted deposition, (<b>b</b>) perpendicular deposition to the rotatory axis, and (<b>c</b>) parallel deposition to the rotatory axis.</p>
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<p>Path planning for bulk deposition with a cross-hatching strategy.</p>
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<p>Metallographic cross-section of a bulk specimen with measurement of the porosity.</p>
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<p>Points of indentation for the HV hardness measurement.</p>
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<p>Influence of the beam diameter on the deposited single-track width and heigh. P<sub>L</sub> = 2800 W; ṁ = 2.2 kg/h; and Q<sub>L</sub> = 8 L/min.</p>
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<p>Resulting single-track geometries at different powder mass flows: (<b>a</b>) single track width and height (<b>b</b>) aspect ratios. d<sub>B</sub> = 1.6 mm; Q<sub>L</sub> = 8 L/min; P<sub>L</sub> = 2000 W for 0.4 kg/h &lt; ṁ &lt; 1.2 kg/h; and P<sub>L</sub> = 2600 W for 1.5 kg/h &lt; ṁ &lt; 2.2 kg/h.</p>
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<p>(<b>a</b>) Single-track aspect ratio and (<b>b</b>) dilution zone depth with variation in beam power. d<sub>B</sub> = 1.6 mm and Q<sub>L</sub> = 8 L/min.</p>
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<p>(<b>a</b>) Single-track aspect ratios and (<b>b</b>) dilution zone depths with variation in powder mass flow and carrier gas flows. d<sub>B</sub> = 1.6 mm; P<sub>L</sub> = 2600 W.</p>
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<p>Resulting coating thicknesses by variation in the hatching distance h. Applied parameter sets are provided in <a href="#coatings-14-00953-t003" class="html-table">Table 3</a>.</p>
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<p>Metallographic cross-sections of coatings deposited with parameter set ṁ = 1.9 kg/h. (<b>a</b>) h = 0.5 and (<b>b</b>) h = 0.6.</p>
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<p>Bonding defects at the end of a weld track at a low hatch distance. (<b>a</b>) h = 0.5 and (<b>b</b>) h = 0.6 with the ṁ = 1.9 kg/h parameter set.</p>
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<p>Metallographic cross-sections and 3D-profilometer images of probes deposited at different angles.</p>
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<p>Metallographic cross-section of the bulk specimen deposited with the high productivity parameter set. (<b>a</b>) Polished cross-section and (<b>b</b>) etched cross-section—resulting porosity: 0.34%.</p>
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<p>(<b>a</b>) Metallographic cross-section of a bulk specimen with 250 deposited layers—porosity: 0.04 %. (<b>b</b>) SEM image of the edge area with identified micro hot cracks.</p>
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<p>Hardness profile of the deposited bulk specimen—average hardness: 910 ± 34 HV.</p>
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22 pages, 23988 KiB  
Article
Analysis of Tribological Properties of Hardfaced High-Chromium Layers Subjected to Wear in Abrasive Soil Mass
by Magdalena Lemecha, Krzysztof Ligier, Jerzy Napiórkowski and Oleksandr Vrublevskyi
Materials 2024, 17(14), 3461; https://doi.org/10.3390/ma17143461 - 12 Jul 2024
Viewed by 606
Abstract
This article presents the results of abrasion wear resistance tests of wear-resistant steel and surfacing under laboratory conditions and natural operation. Abrasion wear resistance determined on the basis of the study by determining geometrical characteristics of the alloying additives using computer image analysis [...] Read more.
This article presents the results of abrasion wear resistance tests of wear-resistant steel and surfacing under laboratory conditions and natural operation. Abrasion wear resistance determined on the basis of the study by determining geometrical characteristics of the alloying additives using computer image analysis methods, as well as examining the changes occurring on the surface of the workpieces and their wear intensity. Based on the results obtained from laboratory tests, it was noted that AR steel exhibited 14 times greater wear than the padding weld. This wear is affected by alloy additives, which, for the padding weld, are chromium additives. The microstructure image shows that soil mass had a destructive effect mainly on the matrix of the material, whereas in the areas with high concentrations of chromium precipitates, this effect was significantly weaker. The operational test results showed that within the area of the tine subjected to hardfacing, the material loss was lower than that for the same area of the tine in the as-delivered state. For the hardfaced tine, a 7% loss of volume was noted in relation to the operating part before testing and following the friction process. However, for the operating part in the as-delivered state, this difference amounted to 12%. Full article
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<p>Test stand diagram: 1—rocker arm, 2—specimen holder, 3—bowl with abrasive mass, 4—abrasive mass, 5—loading mass, 6—specimen.</p>
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<p>Tine surface and position of the A<sub>i</sub> plane.</p>
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<p>AR steel microstructure. Microstructure of tempered martensite with former austenite grain boundaries. Light microscopy. Etched with 3% HNO<sub>3</sub>.</p>
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<p>Fe–C–Cr alloy microstructure: Alloy ferrite with precipitates of chromium carbide and large precipitates of primary M<sub>7</sub>C<sub>3</sub> carbides (Fe,Cr<sub>7</sub>C<sub>3</sub>) against the background of mixed alloy ferrite and M<sub>23</sub>C<sub>6</sub> carbides; light microscopy.</p>
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<p>Fe–C–Cr alloy microstructure subjected to chemical analysis; 1, 2, 3—measurement points for chemical composition.</p>
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<p>EDS analysis results from the areas shown in the Fe–C–Cr alloy microstructure image. (<b>a</b>) X-ray spectrum, (<b>b</b>) map of the distribution of elements.</p>
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<p>Precipitation of chromium carbides in the Fe–C–Cr-based weld deposit; (<b>a</b>) in the longitudinal orientation (longitudinal), (<b>b</b>) in the transverse orientation; 1000× magnification.</p>
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<p>Loss of weight of test materials.</p>
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<p>Surface of the tested materials after wear: (<b>a</b>) overlay based on Fe–C–Cr; (<b>b</b>) AR steel; 1—ploughing, 2—micro-cutting, 3—spalling, 4—scratching, 5—ridging.</p>
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<p>Surface of the tested materials after wear: (<b>a</b>) Fe–C–Cr-based weld; (<b>b</b>) enlargement of the area marked in (<b>a</b>). 1—grooves, 2—carbides participate, 3—spall after removed carbide.</p>
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<p>The cultivator tines used for testing: (<b>a</b>) as-delivered before the testing, (<b>b</b>) as-delivered following the testing, (<b>c</b>) hardfaced before the testing, (<b>d</b>) hardfaced following the testing.</p>
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<p>Volumetric wear characteristics. 1, 2–the surface of the sintered carbide blade, 3, 4–the hardfaced part of the tine.</p>
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<p>A view of the tine surface following testing; (<b>a</b>) in the as-delivered state, (<b>b</b>) hardfaced.</p>
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<p>Test tine parts subjected to analysis.</p>
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<p>Volumetric characteristics of the central section of the hardfaced tine.</p>
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<p>Material losses on the lower surface of the tine.</p>
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<p>Cumulative loss of the padding weld volume.</p>
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<p>View of the hardfaced tine surface.</p>
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<p>Comparison of the volume of the tested elements; (<b>a</b>) in the delivered state, (<b>b</b>) the welded tine.</p>
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<p>View of the hardfaced tine before and after the wear testing.</p>
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31 pages, 5993 KiB  
Review
Effect of Physical Parameters on Fatigue Life of Materials and Alloys: A Critical Review
by Amit Kaimkuriya, Balaguru Sethuraman and Manoj Gupta
Technologies 2024, 12(7), 100; https://doi.org/10.3390/technologies12070100 - 3 Jul 2024
Cited by 2 | Viewed by 5660
Abstract
Fatigue refers to the progressive and localized structural damage that occurs when a material is subjected to repeated loading and unloading, typically at levels below its ultimate strength. Several failure mechanisms have been observed in practical scenarios, encompassing high-cycle, low-cycle, thermal, surface, corrosion, [...] Read more.
Fatigue refers to the progressive and localized structural damage that occurs when a material is subjected to repeated loading and unloading, typically at levels below its ultimate strength. Several failure mechanisms have been observed in practical scenarios, encompassing high-cycle, low-cycle, thermal, surface, corrosion, and fretting fatigue. Fatigue, connected to the failure of numerous engineered products, stands out as a prevalent cause of structural failure in service. Conducting research on the advancement and application of fatigue analysis technologies is crucial because fatigue analysis plays a critical role in determining the service life of components and mitigating the risk of failure. This study compiles data from a wide range of sources and offers a thorough summary of the state of fatigue analysis. It focuses on the effects of different parameters, including hardness, temperature, residual stresses, and hardfacing, on the fatigue life of different materials and their alloys. The fatigue life of alloys is typically high at low temperatures, but it is significantly reduced at high temperatures or under high-stress conditions. One of the main causes of lower fatigue life is residual stress. High-temperature conditions and hardfacing processes cause the development of tensile residual stresses, which in turn decreases fatigue life. But, if the hardness of the material significantly increases due to hardfacing, then the fatigue life also increases. This manuscript focuses on reviewing the research on fatigue-life prediction methods, shortcomings, and recommendations. Full article
(This article belongs to the Section Innovations in Materials Processing)
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<p>Fatigue failure of a bolt [<a href="#B4-technologies-12-00100" class="html-bibr">4</a>].</p>
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<p>Stages of failure in terms of crack length versus time/cycles of service [<a href="#B11-technologies-12-00100" class="html-bibr">11</a>].</p>
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<p>Specimen design: (<b>a</b>) specimen geometry in millimeters, and (<b>b</b>) image of the actual machined specimen [<a href="#B30-technologies-12-00100" class="html-bibr">30</a>].</p>
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<p>(<b>a</b>) Comparison of the number of cycles until failure under the different loading sequences for AA6061, (<b>b</b>) Comparison of the number of cycles until failure under the different loading sequences for AA7075 [<a href="#B30-technologies-12-00100" class="html-bibr">30</a>].</p>
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<p>Stress amplitude for copper in temperature range [<a href="#B17-technologies-12-00100" class="html-bibr">17</a>].</p>
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<p>Experimental setup of the fatigue testing [<a href="#B18-technologies-12-00100" class="html-bibr">18</a>].</p>
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<p>Residual stress relaxation with number of cycles for LSP ATI 718Plus alloy samples tested [<a href="#B41-technologies-12-00100" class="html-bibr">41</a>].</p>
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<p>Change and error bars with the total range of microhardness in ferrite and pearlite during fatigue loading [<a href="#B54-technologies-12-00100" class="html-bibr">54</a>].</p>
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<p>Hardness measurement locations on a weld cross-section [<a href="#B68-technologies-12-00100" class="html-bibr">68</a>].</p>
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<p>Hardness distribution of VR690 joints [<a href="#B68-technologies-12-00100" class="html-bibr">68</a>].</p>
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<p>Hardness distribution of CR690 joints [<a href="#B68-technologies-12-00100" class="html-bibr">68</a>].</p>
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<p>Sample preparation technique for welded joints: (<b>a</b>) steel base material with a U-groove, (<b>b</b>) steel disc, (<b>c</b>) schematic drawing showing the sample preparation concept [<a href="#B81-technologies-12-00100" class="html-bibr">81</a>].</p>
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<p>Comparison of the fatigue data (stress amplitude against loading cycles until failure for E and C welded samples series (<b>a</b>). Typical overview images and details of the fatigue fracture surfaces of (<b>b</b>,<b>d</b>) E- and (<b>c</b>,<b>e</b>) C-weld samples series [<a href="#B82-technologies-12-00100" class="html-bibr">82</a>].</p>
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<p>Fatigue life and fracture of the 7475-T6 Al alloy coated with different thicknesses [<a href="#B85-technologies-12-00100" class="html-bibr">85</a>].</p>
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<p>New rotating bending machine [<a href="#B89-technologies-12-00100" class="html-bibr">89</a>].</p>
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<p>Variations in life for LCF and IP-OP TMF [<a href="#B91-technologies-12-00100" class="html-bibr">91</a>].</p>
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<p>Fatigue life specimen for Al 7075 alloys [<a href="#B15-technologies-12-00100" class="html-bibr">15</a>].</p>
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<p>Effect of residual stresses on fatigue life cycle [<a href="#B15-technologies-12-00100" class="html-bibr">15</a>].</p>
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<p>SENT specimen with V-notch [<a href="#B6-technologies-12-00100" class="html-bibr">6</a>].</p>
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19 pages, 39177 KiB  
Article
Microstructure and Hardness Characteristics of Swing-Arc SAW Hardfacing Layers
by Zhengyu Zhu, Maoyang Ran, Xuyang Li, Pichang Ma, Shubin Liu and Jiayou Wang
Materials 2024, 17(10), 2310; https://doi.org/10.3390/ma17102310 - 13 May 2024
Viewed by 784
Abstract
Hot-rolled backup rolls are widely used in steel rolling and usually need to be repaired by arc hardfacing after becoming worn. However, a corrugated-groove defect commonly occurs on the roll surface due to the uneven hardness distribution in the hardfacing layers, affecting the [...] Read more.
Hot-rolled backup rolls are widely used in steel rolling and usually need to be repaired by arc hardfacing after becoming worn. However, a corrugated-groove defect commonly occurs on the roll surface due to the uneven hardness distribution in the hardfacing layers, affecting the proper usage of the roll. Accordingly, a new swing-arc submerged arc welding (SA-SAW) process is proposed to attempt to solve this drawback. The microstructure and hardness are then investigated experimentally for both SAW and SA-SAW hardfacing layers. It is revealed that a self-tempering effect occurs in the welding pass bottom and the welding pass side neighboring the former pass for both processes, refining the grain in the two areas. In all the zones, including the self-tempering zone (STZ), heat-affected zone (HAZ), and not-heat-affected zone in the welding pass, both SAW and SA-SAW passes crystallize in a type of columnar grain, where the grains are the finest in STZ and the coarsest in HAZ. In addition, the arc swing improves the microstructure homogeneity of the hardfacing layers by obviously lowering the tempering degree in HAZ while promoting the even distribution of the arc heat. Accordingly, the hardness of the SA-SAW bead overall increases and distributes more uniformly with a maximum difference of < 80 HV0.5 along the horizontal direction of the bead. This hardness difference in SA-SAW is accordingly decreased by ~38.5% compared to that of the SAW bead, further indicating the practicability of the new process. Full article
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<p>Schematic illustration of experiment setup: (<b>a</b>) System configuration; (<b>b</b>) Arc swing model.</p>
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<p>Hardfacing layers details for (<b>a</b>) schematic illustration: <span class="html-italic">w</span>11 represents the 1st pass in the 1st layer, <span class="html-italic">w</span>1Ⅹ denotes the 10th pass in the 1st layer, and so forth; (<b>b</b>) dilution rate of each welding layer.</p>
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<p>Schematic illustration of the neighboring two-pass welds in the 6th and 7th layers: Zone 1, 2, 3, and 4 indicate the microstructure analyzing areas.</p>
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<p>Cross-sectional macrograph example of the observation zone for the SA-SAW hardfacing layers: Red points indicate the hardness testing points; Region 1 and Region 2 denote the hardness testing areas with point-to-point intervals of 1 mm and 0.3 mm, respectively.</p>
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<p>Cross-sectional macrographs of single-pass weld at the swing frequency of 3 Hz: (<b>a</b>–<b>d</b>) Effect of swing angle <span class="html-italic">α</span>, (<b>c</b>,<b>e</b>–<b>g</b>) Effect of side-dwell time <span class="html-italic">t</span>.</p>
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<p>Effect of arc swing parameters on weld width and weld thickness at the swing frequency of 3 Hz: (<b>a</b>) Effect of arc swing angle <span class="html-italic">α</span>, (<b>b</b>) Effect of side-dwell time <span class="html-italic">t</span>.</p>
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<p>Macrophotographs of two-pass overlap welding bead at different overlap ratios: (<b>a</b>–<b>d</b>) Surface morphology, (<b>e</b>–<b>h</b>) Cross-section morphology.</p>
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<p>Macrophotographs of the cross-section of hardfacing layers: (<b>a</b>) Hardfacing by SAW, (<b>b</b>) Hardfacing by SA-SAW.</p>
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<p>Optical cross-sectional micrographs of the not-heat-affected weld metal in Zone 1 (<a href="#materials-17-02310-f003" class="html-fig">Figure 3</a>) in the <span class="html-italic">w</span>73 welding pass: (<b>a</b>,<b>b</b>) SAW hardfacing layers, (<b>c</b>,<b>d</b>) SA-SAW hardfacing layers, <span class="html-italic">γ</span>-Austenite, <span class="html-italic">QM</span>-Quenched martensite, <span class="html-italic">TM</span>-Tempered martensite, <span class="html-italic">UC</span>-Undissolved carbide.</p>
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<p>Microstructure in the overlapping Zone 2 (<a href="#materials-17-02310-f003" class="html-fig">Figure 3</a>) between welding passes <span class="html-italic">w</span>73 and <span class="html-italic">w</span>64 in the neighboring SAW layers: (<b>a</b>) Morphology at low magnification, (<b>b<sub>1</sub></b>–<b>b<sub>3</sub></b>) Magnified morphology.</p>
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<p>SAW layer microstructure in the observation zones (<b>b<sub>11</sub></b>–<b>b<sub>33</sub></b>) (<a href="#materials-17-02310-f010" class="html-fig">Figure 10</a>b<sub>1</sub>–b<sub>3</sub>): magnified with ×1000.</p>
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<p>SAW layer microstructure in the observation zones (<b>b<sub>11</sub></b>–<b>b<sub>33</sub></b>) (<a href="#materials-17-02310-f010" class="html-fig">Figure 10</a>b<sub>1</sub>–b<sub>3</sub>): magnified with ×1000.</p>
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<p>Microstructure in the overlapping Zone 3 (<a href="#materials-17-02310-f003" class="html-fig">Figure 3</a>) between welding passes <span class="html-italic">w</span>74 and <span class="html-italic">w</span>63 in the neighboring SA-SAW layers: (<b>a</b>) Morphology at low magnification, (<b>b<sub>1</sub></b>–<b>b<sub>3</sub></b>) Magnified morphology.</p>
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<p>SA-SAW layer microstructure in the observation zones (<b>b<sub>11</sub></b>–<b>b<sub>33</sub></b>) (<a href="#materials-17-02310-f012" class="html-fig">Figure 12</a>b<sub>1</sub>–b<sub>3</sub>): magnified with × 1000.</p>
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<p>SA-SAW layer microstructure in the observation zones (<b>b<sub>11</sub></b>–<b>b<sub>33</sub></b>) (<a href="#materials-17-02310-f012" class="html-fig">Figure 12</a>b<sub>1</sub>–b<sub>3</sub>): magnified with × 1000.</p>
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<p>Microstructure in the overlapping Zone 4 (<a href="#materials-17-02310-f003" class="html-fig">Figure 3</a>) between welding passes <span class="html-italic">w</span>73 and <span class="html-italic">w</span>74: (<b>a</b>,<b>b</b>) in SAW, (<b>c</b>,<b>d</b>) in SA-SAW.</p>
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<p>Hardness distribution of the hardfacing layers in the red-point Region 1 in <a href="#materials-17-02310-f004" class="html-fig">Figure 4</a>: (<b>a</b>,<b>b</b>) SAW, (<b>c</b>,<b>d</b>) SA-SAW.</p>
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<p>Diagram of the hardness testing Region 2 covering the three welding passes of <span class="html-italic">w</span>62, <span class="html-italic">w</span>63, and <span class="html-italic">w</span>55: (<b>a</b>) Illustration, (<b>b</b>) Micrograph of the SA-SAW hardfacing layers.</p>
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<p>Hardness distribution of the red-point Region 2 (<a href="#materials-17-02310-f004" class="html-fig">Figure 4</a>) covering the three welding passes of <span class="html-italic">w</span>62, <span class="html-italic">w</span>63, and <span class="html-italic">w</span>55: (<b>a</b>,<b>b</b>) SAW, (<b>c</b>,<b>d</b>) SA-SAW. The two red dotted lines denote the fusion lines and divide the equipotential diagram into 3 parts, which correspond to an STZ in <span class="html-italic">w</span>62, an STZ in <span class="html-italic">w</span>63, and a HAZ in <span class="html-italic">w</span>55.</p>
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<p>Hardness difference distribution of the hardfacing layers in the red-point Region 1 in <a href="#materials-17-02310-f004" class="html-fig">Figure 4</a>: (<b>a</b>) along the testing-point row, (<b>b</b>) along the testing-point column.</p>
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13 pages, 6236 KiB  
Article
Microstructural Investigations of Weld Deposits from Manganese Austenitic Alloy on X2CrNiMoN22-5-3 Duplex Stainless Steel
by Ion Mitelea, Daniel Mutașcu, Olimpiu Karancsi, Corneliu Marius Crăciunescu, Dragoș Buzdugan and Ion-Dragoș Uțu
Appl. Sci. 2024, 14(9), 3751; https://doi.org/10.3390/app14093751 - 27 Apr 2024
Cited by 1 | Viewed by 1267
Abstract
Duplex stainless steels are materials with high performance under mechanical stress and stress corrosion in chloride ion environments. Despite being used in many new applications such as components for offshore drilling platforms as well as in the chemical and petrochemical industry, the automotive [...] Read more.
Duplex stainless steels are materials with high performance under mechanical stress and stress corrosion in chloride ion environments. Despite being used in many new applications such as components for offshore drilling platforms as well as in the chemical and petrochemical industry, the automotive industry, etc., they face issues of wear and hardness that limit current applications and prevent the creation of new use opportunities. To address these shortcomings, it is proposed to develop a hardfacing process by a special welding technique using a universal TIG source adapted for manual welding with a pulsed current, and a manganese austenitic alloy electrode as filler material. The opportunity to deposit layers of manganese austenitic steel through welding creates advantages related to the possibility of achieving high mechanical characteristics of this steel exclusively in the working area of the part, while the substrate material will not undergo significant changes in chemical composition. As a result of the high strain hardening rate, assisted mainly by mechanical twinning, manganese austenitic alloys having a face-centered cubic crystal lattice (f.c.c) and low stacking fault energy (SFE = 20–40 mJ/m2) at room temperature, exhibit high wear resistance and exceptional toughness. Following cold deformation, the hardness of the deposited metal increases to 465 HV5–490 HV5. The microstructural characteristics were investigated through optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), and Vickers hardness measurements (HV). The obtained results highlighted the feasibility of forming hard coatings on duplex stainless steel substrates. Full article
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<p>The parameters of the pulsed current welding process.</p>
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<p>Macrographic images of the layer—substrate system: (<b>a</b>) one layer deposited; (<b>b</b>) two layers deposited; (<b>c</b>) three layers deposited.</p>
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<p>The microstructure of the base metal.</p>
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<p>Micrograph of the MD–MB interface at the deposition of the first layer.</p>
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<p>Micrograph of the outer layer deposited by hardfacing welding.</p>
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<p>Modes of hammering the deposited layer.</p>
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<p>Optical micrographic image (×1000) of the work-hardened layer.</p>
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<p>SEM image and the concentration profiles of the alloying elements on one side and the other of the interface between the deposited metal and the base metal.</p>
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<p>X-ray diffraction pattern of the substrate.</p>
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<p>X-ray diffraction pattern of the layer microzone near the interface with the substrate material.</p>
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<p>Hardness gradient curve on the cross-section of the layer-substrate system.</p>
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22 pages, 11055 KiB  
Article
Comparison of the Mechanical Properties of Hardfacings Made by Standard Coated Stick Electrodes and a Newly Developed Rectangular Stick Electrode
by Edvard Bjelajac, Andrej Skumavc, Gorazd Lojen, Mirza Manjgo and Tomaž Vuherer
Materials 2024, 17(9), 2051; https://doi.org/10.3390/ma17092051 - 27 Apr 2024
Cited by 1 | Viewed by 785
Abstract
Cladding with a stick electrode is one of the oldest arc processes for adding a deposit on a base material. The process is suitable for outdoor working, but the disadvantages are low productivity and large dilution rates. In this work, a simple solution [...] Read more.
Cladding with a stick electrode is one of the oldest arc processes for adding a deposit on a base material. The process is suitable for outdoor working, but the disadvantages are low productivity and large dilution rates. In this work, a simple solution is proposed, which would enable cladding of a larger area with one pass and decrease the dilution rate at the same time—a new type of electrode was developed, exhibiting a rectangular cross-section instead of a round one. Hardfacings, welded with E Fe8 electrodes according to EN 14 700 Standard were welded on mild steel S355 J2 base material with three different coated stick electrodes. The first one was a commercially available, standard, round hardfacing electrode, the second was the same, but with a thinner coating, and the third one was a newly developed rectangular electrode. All three types had equal cross-sections of the metallic core and the same type of coating. Manufacturing of the rectangular electrodes in the laboratory is explained briefly. One- and multi-layer deposits were welded with all three types. Differences were observed in the arc behavior between the round and rectangular electrodes. With the rectangular electrode, the microstructure of the deposit was finer, penetration was shallower, and dilution rates were lower, while the hardness was higher, residual stresses predominantly compressive, and the results of instrumented Charpy impact tests and fracture mechanics tests were better. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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Figure 1
<p>The cross-section of a coated tubular electrode with a seam: 1—coating, 2—metal tube, and 3—powder core [<a href="#B39-materials-17-02051" class="html-bibr">39</a>].</p>
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<p>Method of laboratory production for rectangular coated stick electrode.</p>
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<p>A rectangular coated electrode for SMAW welding.</p>
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<p>Cross-sections of stick coated electrodes: (<b>a</b>) rectangular electrode (PL); (<b>b</b>) round standard electrode with reduced outer diameter (OE); and (<b>c</b>) round standard electrode.</p>
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<p>Geometry of hardfacings: (<b>a</b>) one-layer and (<b>b</b>) two-layer welds, one pass wide; (<b>c</b>) multi-layer welds, two passes wide; (<b>d</b>) multi-layer welds, several passes wide; (<b>e</b>) one-layer weld, several passes wide; and (<b>f</b>) two-layer welds, several passes wide.</p>
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<p>Principle of dilution of the base and filler metals in hardfacing alloys.</p>
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<p>Plan for hardness measurements.</p>
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<p>Geometry of samples for different tests: (<b>a</b>) Charpy specimen; (<b>b</b>) SENB specimen; and (<b>c</b>) sample for residual stress measurements with a stain gauge rosette.</p>
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<p>Residual stress in construction steels: (<b>a</b>) change in <span class="html-italic">R<sub>p</sub></span><sub>02</sub> with temperature <span class="html-italic">T</span>; (<b>b</b>) weld deformation cycle.</p>
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<p>SMAW arc taken by high-speed camera: (<b>a</b>) rectangular stick electrode (∅1 × 12.56 mm); the arc was traveling from one side to the other and back (yellow arrows); (<b>b</b>) thinned round electrode (∅4/∅6.90 mm); and (<b>c</b>) conventional round-shaped electrode (∅4/∅7.85 mm); the arc stays at the same position (yellow points).</p>
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<p>(<b>a</b>) The arc burns where the distance to weld pool is the shortest; (<b>b</b>–<b>d</b>) as the electrode melts, in the search for the shortest distance to the weld pool, the arc traveles from one edge of the electrode to the other; (<b>e</b>) then the journey back starts; the frequency of the journeys, approx. 3.5–4.5-times per second, was determined from the high-speed-camera videos.</p>
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<p>Welding speed and arc-travel speed: (<b>a</b>) in the case of the round electrode; (<b>b</b>) in the case of the rectangular electrode.</p>
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<p>Macro-sections of hardfacing welds: (<b>a</b>,<b>b</b>) represent the rectangular coated stick electrode; (<b>c</b>,<b>d</b>) represent the round thin-coated electrode (∅4/∅6.90 mm); and (<b>e</b>,<b>f</b>) represent the conventional round coated electrode (∅4/∅7.85 mm).</p>
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<p>Microstructure of hardfacing welds: (<b>a</b>,<b>b</b>) HAZ and WM welded by the rectangular coated stick electrode; (<b>c</b>,<b>d</b>) HAZ and WM welded by the round thin-coated electrode (∅4/∅6.90 mm); (<b>e</b>,<b>f</b>) HAZ and WM welded by the standard round coated electrode (∅4/∅7.85 mm); and (<b>g</b>) base material.</p>
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<p>Results of the hardness measurements on welds made with the rectangular stick electrode (∅1 × 12.56 mm): (<b>a</b>) in the vertical direction; (<b>b</b>) in the horizontal direction.</p>
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<p>Results of hardness measurements on welds made with the thin-coated electrode (∅4/∅6.90 mm): (<b>a</b>) in the vertical direction; (<b>b</b>) in the horizontal direction.</p>
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<p>Results of the hardness measurements on welds made with the conventional coated electrode (∅4/∅7.85 mm): (<b>a</b>) in the vertical direction; (<b>b</b>) in the horizontal direction.</p>
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<p>Results of instrumented Charpy tests: (<b>a</b>) rectangular stick electrode (∅1 × 12.56 mm); (<b>b</b>) thinned round electrode (∅4/∅6.90 mm); (<b>c</b>) conventional round electrode (∅4/∅7.85 mm); and (<b>d</b>) base material.</p>
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<p>Results of fracture mechanics tests: (<b>a</b>) force-<span class="html-italic">CMOD</span> diagram; (<b>b</b>) resistance curves <span class="html-italic">J</span>-Δ<span class="html-italic">a</span>.</p>
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<p>Results of fracture mechanics tests: critical <span class="html-italic">J<sub>IC</sub></span> an <span class="html-italic">K<sub>JIC</sub></span>.</p>
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<p>Fractured surfaces of weld metal welded by: (<b>a</b>) a rectangular stick electrode (∅1 × 12.56 mm); (<b>b</b>) a thinned round electrode (∅4/∅6.90 mm); (<b>c</b>) a conventional round electrode (∅4/∅7.85 mm).</p>
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<p>Fracture surfaces of weld metal from SEM in the area of crack incitation and stable crack growth: (<b>a</b>,<b>b</b>) rectangular stick electrode (∅1 × 12.56 mm); (<b>c</b>,<b>d</b>) thinned round electrode (∅4/∅6.90 mm); and (<b>e</b>,<b>f</b>) conventional round electrode (∅4/∅7.85 mm).</p>
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<p>Results of the residual stress measurements. Strains measured with a three-elemental strain-gauge rosette on hardfacings welded by: (<b>a</b>) a rectangular stick electrode (∅1 × 12.56 mm); (<b>b</b>) a conventional round electrode (∅4/∅7.85 mm).</p>
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<p>Residual stresses in hardfacings welded by: (<b>a</b>) a rectangular stick electrode (∅1 × 12.56 mm); (<b>b</b>) a conventional round electrode (∅4/∅7.85 mm).</p>
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31 pages, 19299 KiB  
Article
Effect of Exothermic Additions in Core Filler on Arc Stability and Microstructure during Self-Shielded, Flux-Cored Arc Welding
by Vasyl Lozynskyi, Bohdan Trembach, Egidijus Katinas, Kostiantyn Sadovyi, Michal Krbata, Oleksii Balenko, Ihor Krasnoshapka, Olena Rebrova, Sergey Knyazev, Oleksii Kabatskyi, Hanna Kniazieva and Liubomyr Ropyak
Crystals 2024, 14(4), 335; https://doi.org/10.3390/cryst14040335 - 31 Mar 2024
Cited by 8 | Viewed by 1426
Abstract
In the conditions of an energy crisis, an important issue is the increase in energy efficiency and productivity of welding and hardfacing processes. The article substantiates the perspective of using exothermic additives introduced into core filler for flux-cored wire arc welding processes as [...] Read more.
In the conditions of an energy crisis, an important issue is the increase in energy efficiency and productivity of welding and hardfacing processes. The article substantiates the perspective of using exothermic additives introduced into core filler for flux-cored wire arc welding processes as a relatively cheap additional heat source, reducing energy consumption when melting filler materials, and increasing the deposition rate. The mixture design (MD) was selected as the design method to optimize the average values of current and voltage, as well as arc stability parameters depending on core filler composition. This article studies the influence of the introduction of exothermic addition (EA), as well as the ratios CuO/C and CuO/Al on arc stability for the FCAW S process. Parameters characterizing arc stability were determined using an oscillograph, and from the obtained oscillograms, an analysis was conducted on arc voltage and welding current signals during flux-cored arc welding. It was determined that various methods can be used to evaluate arc stability, which can be divided into two groups: graphical (current and voltage cyclograms, box plots with frequency histograms, ellipse parameters plotted on current, and voltage cyclograms) and statistical (standard variation and coefficients of variation for welding current and arc voltage). In this paper, a comprehensive evaluation of arc stability depending on the composition of the cored wire filler was carried out. It was determined that the most stable current parameters were observed for the flux-cored wire electrode with an average exothermic addition content at the level of EA = 26.5–28.58 wt.% and a high carbon content (low values of CuO/C = 3.75). Conversely, the lowest values of arc stability (CV(U) and Std(U)) were observed during hardfacing with a flux-cored wire electrode with a high CuO/Al ratio ≥ 4.5 and a content of exothermic addition in the core filler below the average EA < 29 wt.%. Mathematical models of mean values, standard deviation, coefficient of variation for welding current, and arc voltage were developed. The results indicated that the response surface prediction models had good accuracy and prediction ability. The developed mathematical models showed that the ratio of oxidizing agent to reducing agent in the composition of exothermic addition (CuO/Al) had the greatest influence on the welding current and arc voltage characteristics under investigation. The percentage of exothermic mixture in the core filler (EA) only affected the average welding current (Iaw) and the average arc voltage (Uaw). The graphite content expressed through the CuO/C ratio had a significant impact on welding current parameters as well as the coefficient of variation of arc voltage (CV(U)). Two welding parameters were selected for optimization: the mean welding current (Iaw) and the standard deviation of arc voltage (Std(U)). The best arc stability when using exothermic addition CuO-Al in the core filler was observed at CuO/Al = 3.6–3.9, CuO/C = 3.5–4.26, and at an average EA content of 29–38 wt.%. The significant influence of the CuO/Al and CuO/C ratios on arc voltage parameters can also be explained by their impact on the elemental composition of the welding arc (copper, cupric oxide (CuO), and Al2O3). The more complete this reaction, the higher the amount of easily vaporized copper (Cu) in the arc plasma, enhancing arc stability. The influence of core filler composition on the microstructure of deposited metal of the Fe-Cr-Cu-Ti alloy system was investigated. Full article
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<p>Contour surface graphs for (<b>a</b>) filler rate <span class="html-italic">C</span><sub>WF</sub> and (<b>b</b>) core filler density (<span class="html-italic">ρ</span><sub>f</sub>) [<a href="#B79-crystals-14-00335" class="html-bibr">79</a>].</p>
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<p>Contour surface graphs for (<b>a</b>) deposited rate (DR) and (<b>b</b>) spattering factor (SF) [<a href="#B84-crystals-14-00335" class="html-bibr">84</a>].</p>
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<p>Contour surface graphs for (<b>a</b>) the overall transition element factor <span class="html-italic">η</span>(SS) [<a href="#B85-crystals-14-00335" class="html-bibr">85</a>], and 3D graphs for (<b>b</b>) the transition recovery factor <span class="html-italic">η</span>(C) [<a href="#B64-crystals-14-00335" class="html-bibr">64</a>] and (<b>c</b>) the copper recovery factor <span class="html-italic">η</span>(Cu) [<a href="#B64-crystals-14-00335" class="html-bibr">64</a>].</p>
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<p>An overall block diagram elaborating the algorithm for conducting a design plan.</p>
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<p>Experimental setup for hardfacing.</p>
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<p>Dynamic characteristics of voltage and current with varying composition of core filler: (<b>a</b>) FCAW-SS-E1; (<b>b</b>) FCAW-SS-E2; (<b>c</b>) FCAW-SS-E3; (<b>d</b>) FCAW-SS-E4; (<b>e</b>) FCAW-SS-E5; (<b>f</b>) FCAW-SS-E6; (<b>g</b>) FCAW-SS-E7; (<b>h</b>) FCAW-SS-E8; and (<b>i</b>) FCAW-SS-E9.</p>
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<p>The effect of the composition of core filler on the average welding current and average arc voltage.</p>
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<p>The effect of the composition of core filler on (<b>a</b>,<b>b</b>) the coefficient of variation and the standard variation of the arc voltage and welding current, respectively.</p>
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<p>Box plots for the medians, quartiles, and scatter of the (<b>a</b>) welding current depending on the composition of the core filler of flux-cored wire electrodes and histograms (<b>b</b>–<b>j</b>) of the welding current distribution for all FCAW-S, where DQ1 = Q1–MP—difference of the median (Q1) from the midpoint (MP).</p>
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<p>Box plots for the medians, quartiles, and scatter of the (<b>a</b>) arc voltage depending on the composition of the core filler of flux-cored wire electrodes and histograms (<b>b</b>–<b>j</b>) of the arc voltage distribution for all FCAW-SS, where DQ1 = Q1–MP—difference of the median (Q1) from the midpoint (MP).</p>
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<p>Current and voltage cyclograms (scatter density plot) with varying compositions of core filler: (<b>a</b>) FCAW-SS-E1; (<b>b</b>) FCAW-SS-E2; (<b>c</b>) FCAW-SS-E3; (<b>d</b>) FCAW-SS-E4; (<b>e</b>) FCAW-SS-E5; (<b>f</b>) FCAW-SS-E6; (<b>g</b>) FCAW-SS-E7; (<b>h</b>) FCAW-SS-E8; and (<b>i</b>) FCAW-SS-E9, where AEA—arc extinetion area; SCA—short-circuiting area.</p>
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<p>Current and voltage cyclograms (scatter density plot) with varying compositions of core filler: (<b>a</b>) FCAW-SS-E1; (<b>b</b>) FCAW-SS-E2; (<b>c</b>) FCAW-SS-E3; (<b>d</b>) FCAW-SS-E4; (<b>e</b>) FCAW-SS-E5; (<b>f</b>) FCAW-SS-E6; (<b>g</b>) FCAW-SS-E7; (<b>h</b>) FCAW-SS-E8; and (<b>i</b>) FCAW-SS-E9, where AEA—arc extinetion area; SCA—short-circuiting area.</p>
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<p>Diagram of predicted values versus actual values for (<b>a</b>) mean welding current, (<b>b</b>) coefficients of variation, (<b>c</b>) standard variation of welding current, (<b>d</b>) mean arcvoltage, (<b>e</b>) coefficients of variation, and (<b>f</b>) standard variation of arc voltage.</p>
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<p>Pareto diagrams of effect of core filler composition on (<b>a</b>) mean welding current, (<b>b</b>) coefficients of variation, (<b>c</b>) standard variation of welding current, (<b>d</b>) meanarc voltage, (<b>e</b>) standard variation, and (<b>f</b>) coefficients of variation of arc voltage.</p>
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<p>Response surface plot (3D) and contour plot (2D) showing the effects of variables on mean welding current (<b>a</b>) 2D and (<b>b</b>) 3D; standard variation of welding current (<b>c</b>) 2D and (<b>d</b>) 3D; and coefficients of variation of welding current (<b>e</b>) 2D and (<b>f</b>) 3D.</p>
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<p>Response surface plot (3D) and contour plot (2D) showing the effects of variables on mean arc voltage (<b>a</b>) 2D and (<b>b</b>) 3D; standard variation of arc voltage (<b>c</b>) 2D and (<b>d</b>) 3D; and coefficients of variation of arc voltage (<b>e</b>) 2D and (<b>f</b>) 3D.</p>
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<p>Interpretation diagram of optimal value areas.</p>
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<p>(<b>a</b>) Pareto chart, (<b>b</b>) plot of observed and predicted values, (<b>c</b>) response surface, and (<b>d</b>) contour surface graphs for heat input <span class="html-italic">Q<sub>in</sub></span>.</p>
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<p>(<b>a</b>) Pareto chart, (<b>b</b>) plot of observed and predicted values, (<b>c</b>) response surface, and (<b>d</b>) contour surface graphs for heat input <span class="html-italic">Q<sub>in</sub></span>.</p>
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<p>Macrographic images of weld bead hardfacing using (<b>a</b>) FCAW-SS-E5; (<b>b</b>) FCAW-SS-E6.</p>
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<p>CCT diagram for deposited metals of hardfacing using (<b>a</b>) FCAW-SS-E5; (<b>b</b>) FCAW-SS-E6.</p>
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<p>The phase composition of the deposited metals during the welding cycle (rate of heating <span class="html-italic">RH</span> = 1000 °C/s, cooling rate <span class="html-italic">CR</span> = 45 °C/s, graine size 13 μm) during hardfacing with a self-shielded, flux-cored wire electrode with indexes (<b>a</b>) FCAW-SS-E5; (<b>b</b>) FCAW-SS-E6.</p>
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<p>Microstructure of specimens of hardfacing using (<b>a</b>) FCAW-SS-E5; (<b>b</b>) FCAW-SS-E6.</p>
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<p>XRD pattern of specimens of hardfacing using (<b>a</b>) FCAW-SS-E5; (<b>b</b>) FCAW-SS-E6.</p>
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17 pages, 7742 KiB  
Article
Cavitation Erosion of the Austenitic Manganese Layers Deposited by Pulsed Current Electric Arc Welding on Duplex Stainless Steel Substrates
by Ion Mitelea, Daniel Mutașcu, Ion-Dragoș Uțu, Corneliu Marius Crăciunescu and Ilare Bordeașu
Crystals 2024, 14(4), 315; https://doi.org/10.3390/cryst14040315 - 28 Mar 2024
Viewed by 2847
Abstract
Fe-Mn-Cr-Ni alloys like Citomangan, delivered in the form of powders, tubular wires, and coated electrodes, are intended for welding deposition operations to create wear-resistant layers. Their main characteristic is their high capacity for surface mechanical work-hardening under high shock loads, along with high [...] Read more.
Fe-Mn-Cr-Ni alloys like Citomangan, delivered in the form of powders, tubular wires, and coated electrodes, are intended for welding deposition operations to create wear-resistant layers. Their main characteristic is their high capacity for surface mechanical work-hardening under high shock loads, along with high toughness and wear resistance. In order to increase the resistance to cavitation erosion, hardfacing of Duplex stainless steel X2CrNiMoN22-5-3 with Citomangan alloy was performed using a new welding technique, namely one that uses a universal TIG source adapted for manual welding with a coated electrode in pulsed current. Cavitation tests were conducted in accordance with the requirements of ASTM G32—2016 standard. Comparing the characteristic cavitation erosion parameters of the manganese austenitic layer, deposited by this new welding technique, with those of the reference steel, highlights an 8–11 times increase in its resistance to cavitation erosion. Metallographic investigations by optical microscopy and scanning electron microscopy (SEM), as well as hardness measurements, were carried out to understand the cavitation phenomena. Full article
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<p>Microstructure of the base metal.</p>
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<p>The standard vibrating device with piezoceramic crystals: (<b>a</b>)—general image; (<b>b</b>)—image during the cavitation attack; (<b>c</b>)—the head of the sonotrode in which the cavitation sample is fixed; (<b>d</b>)—the vibrating mechanical system with the sample fixed in the sonotrode.</p>
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<p>Geometry of the samples exposed to cavitation. The blue dashed line is the symmetry axis of the sample.</p>
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<p>Histogram of the hardness values for the layer—substrate system components.</p>
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<p>The variation of cumulative mass losses with the duration of cavitation attack ((<b>a</b>)—1 deposited layer, (<b>b</b>)—2 deposited layers, (<b>c</b>)—3 deposited layers).</p>
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<p>The variation of cumulative mass losses with the duration of cavitation attack ((<b>a</b>)—1 deposited layer, (<b>b</b>)—2 deposited layers, (<b>c</b>)—3 deposited layers).</p>
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<p>The variation of erosion rate with the duration of cavitation attack ((<b>a</b>)—1 deposited layer, (<b>b</b>)—2 deposited layers, (<b>c</b>)—3 deposited layers).</p>
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<p>Histogram showing the comparison of cavitation erosion resistance.</p>
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<p>SEM microstructural image of a cross-section through the coating-substrate system: (<b>a</b>) ×100 magnification; (<b>b</b>) ×1000 magnification.</p>
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<p>SEM microstructural image of a cross-section through the coating-substrate system: (<b>a</b>) ×100 magnification; (<b>b</b>) ×1000 magnification.</p>
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<p>SEM microstructural image (<b>a</b>), dispersion spectrum (<b>b</b>), and chemical composition (<b>c</b>) of the first deposited layer.</p>
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<p>SEM microstructural image (<b>a</b>), dispersion spectrum (<b>b</b>), and chemical composition (<b>c</b>) of the last deposited layer.</p>
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<p>SEM microstructural image (<b>a</b>), dispersion spectrum (<b>b</b>), and chemical composition (<b>c</b>) of the last deposited layer.</p>
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<p>Topography (SEM image) of the surfaces tested for cavitation for 165 min: (<b>a</b>)—base metal; (<b>b</b>)—hardened layer.</p>
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14 pages, 9642 KiB  
Article
Abrasive Wear Properties of Wear-Resistant Coating on Bucket Teeth Assessed Using a Dry Sand Rubber Wheel Tester
by Zhongxin Wang, Long Sun, Dong Wang, Bo Song, Chang Liu, Zhenning Su, Chaobin Ma and Xiaoyong Ren
Materials 2024, 17(7), 1495; https://doi.org/10.3390/ma17071495 - 26 Mar 2024
Viewed by 1381
Abstract
Ni60-WC coatings with different WC contents on the bucket tooth substrates were pre- pared using laser cladding technology. Their abrasive wear properties were assessed using the dry sand rubber wheel test system. The substrate and the hard-facing layer were tested for comparison. The [...] Read more.
Ni60-WC coatings with different WC contents on the bucket tooth substrates were pre- pared using laser cladding technology. Their abrasive wear properties were assessed using the dry sand rubber wheel test system. The substrate and the hard-facing layer were tested for comparison. The results showed that the hardness of the Ni60-WC coatings increased with the increase in WC content. The wear resistance of the bucket tooth substrate was greatly improved by hard-facing and laser cladding Ni60-WC coatings. The wear rate of the hard-facing layer was reduced to 1/6 of that of the tooth substrate. The wear rate of the laser cladding coatings with 20–40 wt.% WC was similar to that of the hard-facing layer. It is worth mentioning that the wear rate of the coatings with 60–80 wt.% WC was only 1/4 of that of the hard-facing layer. Micro-cutting with surface plastic deformation was the main wear mechanism of the substrate to form narrow and deep furrows. The wear mechanism of the hard-facing layer was mainly plastic deformation with a wide groove, and the surface cracks promoted the removal of the material. The removal of the binder phase caused by micro-cutting was the main wear mechanism of the laser cladding Ni60-WC coatings. However, the hard phase of WC hinders micro-cutting and plastic deformation, which improves the wear resistance of the coating. Full article
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<p>The real image of the MLG-130A dry sand rubber wheel test system (<b>a</b>) and the schematic presentation of the test method (<b>b</b>).</p>
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<p>Typical SEM image of the quartz sand used in this work.</p>
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<p>Typical macroscopic images of the specimens: (<b>a</b>) bucket tooth after wire-electrode cutting, (<b>b</b>) substrate, (<b>c</b>) hardfacing specimen, and (<b>d</b>–<b>g</b>) laser cladding specimens.</p>
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<p>The cross-section images of the hardfacing sample and laser cladding samples with different contents of WC addition.</p>
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<p>Typical macroscopic images of the specimens before dry sand rubber wheel tests.</p>
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<p>Typical SEM images of the surface of the specimens before dry sand rubber wheel tests: (<b>a</b>) substrate, (<b>b</b>) hardfacing, (<b>c</b>) LC-20WC, (<b>d</b>) LC-40WC, (<b>e</b>) LC-60WC, and (<b>f</b>) LC-80WC.</p>
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<p>The cross-section images of the hardfacing and laser cladding samples after grinding and polishing.</p>
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<p>XRD patterns of the Ni60 alloy powder and LC-80WC laser cladding coating.</p>
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<p>Vickers hardness of the samples (<b>a</b>) and the corresponding indentation images: (<b>b</b>) substrate, (<b>c</b>) hardfacing, (<b>d</b>) LC-20WC, (<b>e</b>) LC-40WC, (<b>f</b>) LC-60WC, and (<b>g</b>) LC-80WC.</p>
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<p>Wear volume (<b>a</b>) and wear rate (<b>b</b>) of the samples.</p>
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<p>Typical photos and 3D white-light interferograms of the abraded surface of the substrate (<b>a</b>) and hardfacing layer (<b>b</b>) after the dry sand rubber wheel tests.</p>
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<p>Typical photos and SEM images of the abraded areas of the substrate (<b>a</b>–<b>c</b>) and hard-facing layer (<b>d</b>–<b>f</b>) after the dry sand rubber wheel tests. The red arrow represents the sliding direction during the wear test.</p>
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<p>Typical photo and SEM image of the crack wear area of the hard-facing layer. The red arrow represents the sliding direction during the wear test.</p>
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<p>Typical photos and 3D white-light interferograms of the abraded surface of the laser cladding coating with different WC addition: (<b>a</b>) 20 wt.%, (<b>b</b>) 40 wt.%, (<b>c</b>) 60 wt.%, and (<b>d</b>) 80 wt.%. The red arrow represents the sliding direction during the wear test.</p>
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<p>Typical photos and SEM images of the abraded areas of t of the laser cladding coating with different WC addition: (<b>a</b>–<b>c</b>) 20 wt.%, (<b>d</b>–<b>f</b>) 40 wt.%, (<b>g</b>–<b>i</b>) 60 wt.%, and (<b>j</b>–<b>l</b>) 80 wt.%. The red arrow represents the sliding direction during the wear test. The points A and B in subgraph (<b>c</b>) refer to the positions where the EDS is tested in <a href="#materials-17-01495-t002" class="html-table">Table 2</a>.</p>
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<p>Schematic description of the different abrasive wear mechanisms of the substrate (<b>a</b>), hardfacing layer (<b>b</b>), and laser cladding coating (<b>c</b>).</p>
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32 pages, 3871 KiB  
Review
Surface Modification of 42CrMo Steels: A Review from Wear and Corrosion Resistance
by Zhendong Zhang, Di Wang, Guanglei Liu, Yiyi Qian, Yuquan Xu and Dingding Xiang
Coatings 2024, 14(3), 337; https://doi.org/10.3390/coatings14030337 - 12 Mar 2024
Cited by 4 | Viewed by 2541
Abstract
This work reviews surface modification techniques for improving the wear and corrosion resistance of 42CrMo steel. The advantages and disadvantages of various methods, including thermal spraying, deposition, hardfacing, laser cladding, nitriding, and laser surface treatment, are discussed. The review elaborates on the materials [...] Read more.
This work reviews surface modification techniques for improving the wear and corrosion resistance of 42CrMo steel. The advantages and disadvantages of various methods, including thermal spraying, deposition, hardfacing, laser cladding, nitriding, and laser surface treatment, are discussed. The review elaborates on the materials commonly employed in laser cladding technology, including iron-based, cobalt-based, nickel-based, and high-entropy alloys and reinforced composite coatings. Furthermore, the mechanisms and methods of improving the wear and corrosion resistance of 42CrMo steel are summarized. Finally, this review presents research shortcomings and future opportunities of surface modification techniques. This review also provides a theoretical guide for the application of 42CrMo steel. Full article
(This article belongs to the Special Issue Corrosion and Wear Resistant Alloy/Metal Coatings)
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<p>(<b>a</b>) Number of publications for each surface modification technique applied to 42CrMo steel; (<b>b</b>) percentage of the number of surface coating materials applied to 42CrMo steel.</p>
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<p>Mechanism of each surface modification technology: (<b>a</b>) thermal spraying; (<b>b</b>) chemical vapor deposition; (<b>c</b>) hardfacing; (<b>d</b>) laser cladding; (<b>e</b>) nitriding; (<b>f</b>) laser surface transformation hardening or laser surface melting.</p>
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<p>(<b>a</b>–<b>c</b>) EDS images; (<b>d</b>) BSE micrograph of the LC HSS alloys; (<b>e</b>,<b>f</b>) EBSD phase map of LC1 and inverse pole figures [<a href="#B33-coatings-14-00337" class="html-bibr">33</a>].</p>
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<p>Worn morphologies of Fe<sub>10</sub>Co<sub>10</sub>Ni<sub>10</sub>Cr<sub>4</sub>Mo<sub>6</sub>B<sub>x</sub>Si<sub>10-x</sub> coatings: (<b>a</b>) B<sub>10</sub>Si<sub>0</sub>; (<b>b</b>) B<sub>7</sub>Si<sub>3</sub>; (<b>c</b>) B<sub>5</sub>Si<sub>5</sub>; (<b>d</b>) B<sub>3</sub>Si<sub>7</sub>; (<b>e</b>) B<sub>0</sub>Si<sub>10</sub>; (<b>f</b>) remelting once; (<b>g</b>) remelting twice [<a href="#B42-coatings-14-00337" class="html-bibr">42</a>].</p>
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<p>(<b>a</b>) Schematic diagram of the preparation process of the ordered microporous wear-resistant self-lubricating integrated material; (<b>b</b>) schematic diagram of the anti-friction and wear-resistance mechanism [<a href="#B126-coatings-14-00337" class="html-bibr">126</a>].</p>
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<p>The 42CrMo steel surface coating wear resistance mechanism: (<b>a</b>) improving the compounds of the coating; (<b>b</b>) lubricating layer; (<b>c</b>) improving the coating defects.</p>
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<p>(<b>a</b>) Zn-Fe coating; (<b>b</b>) Y-modified Zn-Fe coating [<a href="#B132-coatings-14-00337" class="html-bibr">132</a>].</p>
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<p>Schematic diagram of the corrosion resistance mechanism of 42CrMo steel.</p>
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