Surface Of Steel Substrate Research Articles

Structural, mechanical, and oxidation resistance properties of double glow plasma Ta[sbnd]W alloys

To enhance the performance of surface coatings on weaponry, TaW alloy layers with various W contents (7, 11.5, 13, 14, 14.5 and 16 at. %) were prepared on the surface of a PCrNi3MoVA gun steel substrate using double-glow plasma surface metallurgy technology. Mechanical properties, friction wear, and oxidation resistance were studied using scratch, hardness, and tribometer testers. The mechanical properties, interfacial properties, and effects on the oxidation performance of the gun steel substrate of the TaW alloy layer were calculated using first principles. The results indicated that the surface and cross-sectional microstructures of the TaW alloy layers were dense and free from obvious defects. With increasing W content, the thickness, hardness, and adhesive strength of the TaW alloy layer increased, and the coefficient of friction and wear rate decreased. The results of the calculations indicate that an increase in the W content enhances the elastic modulus of the TaW alloy and improves its brittleness, strength, and hardness. Doping with Ta and W atoms can increase the vacancy formation energy of Fe atoms in the Fe supercell, the adsorption energy of O atoms on the surface of Fe(110), and the diffusion barrier of O atoms in the Fe supercell and on the Fe(110) surface. Interdoping of Ta, W and Fe atoms at the Fe(110)/Ta-W(110) interface improved the bonding strength and stability of the interface, and the FeTa and FeW chemical bonds formed at the Fe(110)/Ta-W(110) interface ensured stable bonding at the interface. The incorporation of W into the TaW alloy layer enhanced both the mechanical and frictional properties of the alloy. It is well established that TaW alloys improve the antioxidant properties of gun steel substrates, thereby enhancing the performance of coatings on weaponry.

Electrochemical synthesis of vanadium boride powders from their oxide salts

A novel environmentally friendly electrochemical method for synthesizing vanadium boride powders from oxide-based electrolytes was introduced. During this process, co-depositions of vanadium and boron atoms took place on the surface of the low alloyed steel substrates at various stoichiometries, VxBy (x≥1; y≥1). The effects of critical electrolysis parameters namely current density (70, 100, 200, 500 mA/cm2), and temperature (900, 950, 1000 °C) were investigated systematically. The X-ray diffraction (XRD) analyses revealed that at low current density (70 mA/cm2) VB is the main phase; whereas, VB2 became a dominant structure at 100 and 200 mA/cm2. However, at high current densities like 500 mA/cm2 mixed borides containing VB- V3B4- V2B3 -VB2 were detected. The electrolysis temperatures did not cause major variations in the composition of synthesized borides. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) as well as grain size investigations indicated that there is no significant influence of electrolysis conditions on the particle size and it is possible to manufacture high-quality, stoichiometric VB, and VB2 powders with ≈ 4 µm particle size. The best parameters for producing powders containing primarily VB and VB2 powders were determined as 1000 °C, 70 mA/cm2, and 900 °C, 200 mA/cm2, respectively.

Improvement of AISI 316L laser cladding properties by high-frequency vibration process

In the present paper, a unique laser cladding-assisted high-frequency vibration device was applied to prepare the AISI 316L cladding layer by laser cladding on the surface of the AISI 316L stainless steel substrate. The macroscopic morphology, microstructure, microhardness, and wear resistance of the cladding layer were analyzed by optical microscope, scanning electron microscope, Vickers microhardness tester, friction and wear tester, and three-dimensional optical profiler. The laser cladding-assisted high-frequency vibration device uses a high-frequency oscillator with a fixed frequency (20 KHz) to transfer vibration energy through the probe in contact with the substrate and close to the molten pool. This paper explores the effect of different laser powers on the dilution rate of the cladding layer, compares and observes the cross-sectional morphology and microstructure of the cladding layer with and without high-frequency vibration, and analyzes the reasons for the different results.

Exploring the adsorption of 4,4’-[oxalylbis(imino)]bis(2-hydroxybenzoic acid) layer at steel/biogasoline interface by the combined electrical-optical-simulation approach

Reactions at the steel/biogasoline interface trigger the adsorption of 4,4’-[Oxalylbis(imino)]bis(2-hydroxybenzoic Acid) (ODA) layer on the steel surface, thereby activating a mechanism that inhibited the early reactions. Exploring the conditionally deposited ODA layer requires a combined approach, including electrical, optical, and simulation techniques to track the film development and coating characteristics over time, and with the assistance of atomic force microscopy, quantum chemistry (DFT), and molecular dynamics (MD) simulations to reveal the adsorption mechanism of the ODA layer at steel/biogasoline interface. The four experimental ODA concentrations were conducted, related to the simulated un-coverage, undersaturated-, saturated-, and oversaturated-coverage model of the adsorbate on the adsorbent. The EC-RS data examines surface compositions and their distribution, coating/solution interface, and coating/substrate adhesion by, respectively, Raman spectroscopy (RS), electrochemical impedance spectroscopy (EIS), and current density—potential (I-V) scan. Namely, RS pointed out that an organic layer was established when ODA was added to the simulated biogasoline. EIS results revealed insulator behaviors of the ODA layer at the solid–liquid interface, limiting the charge transfer between the steel substrate and the biogasoline. I-V results showed an increase in surface current density and a decrease in surface polarization resistance of the coating with the rise in ODA concentration. The AFM morphology profile verified the degradation of the sample’s surface when exposed to biogasoline and the minimization of surface damage by ODA addition through adsorption. The simulation findings revealed that the adsorption of ODA on steel preferred physisorption, reaching the most stable state at a specified temperature and ODA concentration. The adsorption mechanism follows the Generalized Langmuir isotherm. The adsorbate (ODA molecules) can produce a transition phase with the steel substrate surface, which modifies the surface thermodynamic characteristics. The combined electro-optical-simulation technique can be applied to investigate various surface phenomena (reactions, catalyzes, adsorption). It especially helps to understand the protective mechanism of inhibitors in different media.

Molecular dynamics simulations and analyzation of Cu deposited on stainless steel substrate surfaces

Copper (Cu) is used in integrated circuits and microdevices and has the potential to replace aluminum alloys due to its low resistivity, strong electromigration properties, and affordability. However, a significant factor that influences the performance of devices at the micro and nano scales is the surface roughness of the deposits. LAMMPS software is employed to simulate the deposition Cu on an ideal state for a stainless-steel substrate. The deposition process and deformation behavior of Cu on the surface and the roughness of the deposition surface are analyzed. Taking the deposition process of Cu atoms as an object, the effects of different atomic numbers, different temperatures, different velocities, and different heights on the surface roughness of the deposits were investigated. The atomic structure composition of the deposition velocity is analyzed, and the radial distribution function is analyzed to reveal the microscopic mechanism of action. The results of the theoretical deposition and analysis show that the surface roughness increases with the number of atoms deposited and decreases with increasing substrate temperature. The surface roughness first decreases and then, after some fluctuation, stays constant at a particular level with increasing velocity. Additionally, as the deposition height increases, the surface roughness reduces. There is a nonlinear relationship between the various components and the deposited surface roughness. The surface quality of deposits can be improved during the deposition process by optimizing the deposition parameters of deposition atoms, substrate temperature, deposition velocity, and deposition height.

Microstructure and properties of WC-reinforced AlCoCrFeNiSi high entropy alloy coatings prepared via high-velocity arc spraying

In this research, (AlCoCrFeNiSi)100-x(WC)x (x=0, 20 and 40 wt%) high entropy alloy (HEA) coatings were successfully deposited on the surface of Q235 steel substrate using high-velocity arc spraying method. The study investigated the presence of WC particles on the phase composition, microstructure, tensile bonding strength, and corrosion behavior of the HEA coatings. X-ray diffraction analysis revealed that without WC particles, the predominant phase in the coating was a face-centered cubic (FCC). However, when 20 wt% and 40 wt% of WC particles were added, the phase composition shifted to include FCC, body-centered cubic (BCC), W3C, Cr7C3, and other carbides. The WC particles also reduced the crystalline grain size of the coatings from 14.75 nm to 10.34 nm. The microhardness value increased from 252.5 HV0.1 to a peak of 529.9 HV0.1, as the content of WC increased representing a microhardness improvement factor ranging from 1.4 to 3 times that of the substrate. The tensile bonding strength of the coatings was also enhanced with WC content. The coating with 40 wt% WC particles demonstrated the highest tensile bonding strength of 40.23 MPa. The cohesion, adhesion, and glue failures occurred after the tensile test, with adhesion failure being more prominent in the coatings without WC particles and glue failure being more prominent in the WC-reinforced coatings. Compared to the Q235 steel substrate, the coated samples showed enhanced resistance against corrosion due to the formation of the passive oxide layers. The effective resistance against corrosion was attained when the proportion of WC particles was 20 wt%, displaying the least values for corrosion current density and corrosion rate in 3.5 wt% NaCl solution. Examination through SEM and XPS analysis indicated that the coatings’ structures and the formation of protective passive layers enhanced the corrosion resistance.

Study on Microstructure and Wear Resistance of WC-based Cermet Coatings Prepared by HVAF

Abstract To mitigate the risk of vapor corrosion damage to the overflow mechanical parts, WC-based metal-ceramic coatings were applied to the surface of a 45-gauge steel substrate by supersonic air-assisted flame spraying (HVAF). The mechanical and wear-resistant qualities of the coating were identified by Vickers micro-hardness, ball-disc friction, and wear test, as well as optics, scanning electron, X-ray diffractometer, and white light interferometer systems. The findings demonstrate the layered structure of the WC-based coating, which is made up of the bonded phase and its distribution of hard phase particles that are diffusely dispersed. The coating is free of cracks, inclusions, and other defects, and its structure and organization are dense with a porosity of 0.86 ± 0.05%. The phenomenon of oxidative decarburization did not occur in the process of preparing the WC hard phase for WC-based metal-ceramic coatings. As a result, the coating’s micro-hardness of 11.83 ± 0.55 GPa is eight times that of the substrate. The results of comparing the three-dimensional abrasion patterns of the coating and the substrate reveal that the coating has superior abrasion resistance because its width and depth of abrasion are smaller than that of the substrate and a lot of furrows have formed on the substrate material’s surface. In contrast, the sprayed layer only had faint traces of abrasion. After three years of actual service, the impeller surface coating is essentially unaltered, which effectively addresses the issue of vapor corrosion damage to the slurry pump’s impeller and extends the pump’s service life to guarantee the overflow mechanical components operate safely and steadily.

Numerical and experimental study on effect of induction heating parameters on the coating of Zn layer on mild steel

The objective of the study is to determine the most effective induction heating parameters for melting pure zinc selectively over the mild steel substrate surface. The numerical simulation on effect of induction heating parameters on the mild steel substrate is studied using COMSOL Multiphysics 5.6 software. The optimised effective parameters are used for the experimental analysis for the validation. Variables such as coil configuration, stand-off distance (SOD), coil current and frequency were systematically changed, and optimal settings were chosen on the basis of time temperature contour curve and the heating rate within the material. Results of the numerical analysis portrayed that a pancake coil geometrical configuration, SOD of 2 mm, coil current of 300 A and alternating frequency of 300 kHz were found as the optimum set of parameters for the effective surface repair. An experimental investigation was carried out by depositing a thin layer of zinc on mild steel substrate using the optimized parameters. The surface integrity of the coated specimen was examined through the high-resolution optical microscopy, X-ray diffraction and electron back scattered diffraction (EBSD) techniques. The hardness property of the coated specimen was examined with a Vickers microhardness tester. The microstructure analysis and hardness measurement showed that consistent coating is achieved without affecting the base metal/substrate properties. The experimental results very much coincide with the numerical simulation.

Microstructure and properties of Co based laser cladded composite coatings

Abstract Coatings deposition using different materials and various techniques are a viable method to improve the surface properties of alloys, especially the surface strength with improved tribological properties. In this study, a series of Co-based reinforced composite coatings containing different ratios of WC–CoCr–Ni particles were fabricated by laser cladding onto the surface of an AISI 904L stainless steel substrate. The main goal of this experimental work was to determine the influence of the WC particle addition on the structure and properties of the obtained Co composite coating in terms of improving the sliding wear resistance without negative influence the corrosion resistance in chloride media. The effect of the WC particles onto the microstructure, phase composition, microhardness, wear and corrosion properties, was investigated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) in association with the evolution of the friction coefficient and that of the polarization curves, respectively. The achieved results have shown that the new phase composition, especially developed due to the remelting of the WC phase, led to an improvement of the wear resistance. No significant changes were recorded after the electrochemical tests evaluation.

Improving the wettability of oxide layers to enhance the bonding strength of shot-blasting steel substrates by using simple resin pre-coating method

This study reveals the micro-structure of the naturally oxidized shot-blasting steel substrate surface and uses a simple resin pre-coating (RPC) approach to fully wet the substrate surface for a stronger adhesive bonding effect. RPC solutions are made of around 90% acetone and 10% resin without hardener, which can be sprayed or brushed onto the steel substrate surface. To demonstrate the wetting effect of RPC treatment on the oxide layer, a single lap shear (SLS) test is conducted to measure the shear strength of grit-blasting and naturally oxidized shot-blasting steel substrates under six different concentrations of RPC solutions. Results showed that after being treated with a 5 wt% RPC solution, the average shear strength of grit-blasting and naturally oxidized shot-blasting specimens increased by 27% and 20% respectively. Meanwhile, it has been observed that the average shear strength of naturally oxidized shot-blasting specimens treated with a 5 wt% RPC solution (15.53 MPa) is slightly higher than that of grit-blasting specimens without RPC treatment (15.45 MPa). This finding indicated that RPC treatment could effectively wet the oxide layer on the surface of shot-blasting steel substrates, removing the need of grit-blasting for steel substrates. Consequently, RPC treatment can simplify on-site processes and reduce environmental pollution.

Effects of Nb content on the microstructure and properties of CoCrFeMnNiNbx high-entropy alloy coatings by laser cladding

CoCrFeMnNiNbx (x = 0, 0.25, 0.5, 0.75, and 1.0) high-entropy alloy coatings were prepared on the AISI 1045 steel substrate surface by laser cladding to explore the effects of different Nb content on the microstructure, microhardness, wear resistance, and corrosion resistance of high entropy alloy coatings. The microstructure of CoCrFeMnNi was composed of single face-centered cubic (FCC) solid-solution phases without Nb addition. The high-entropy alloy coating was mainly composed of a dual-phase structure of the FCC and Laves phases after Nb addition. Nb addition transformed the microstructure of coatings from hypoeutectic to eutectic and hypereutectic compositions. The microhardness of CoCrFeMnNiNbx high-entropy alloy coatings increased gradually with the increase of Nb content. When Nb content x was 1, the average microhardness of coatings was optimal (416.54 HV0.5), which was 2.21 times that of Nb0. The wear resistance of CoCrFeMnNiNbx high-entropy alloy coatings increased gradually with the increase of Nb content, and the wear volume decreased from 0.0739 to 0.0145 mm3. The primary mechanisms responsible for friction and wear were identified as adhesive wear and abrasive wear. The corrosion resistance of coatings first increased and then decreased with the increase of Nb content. When Nb content was 0.75, the passivation film on the coating surface was the stablest and densest, with the optimal corrosion resistance. The results in the work provide a theoretical reference for preparing high-entropy alloy coatings with Nb content.

Effects of Ni-precoating on hydrogen intrusion/emission behavior in Al-Si-coated hot-press-forming steel sheets

In Al-Si-coated hot-press-forming (HPF) steels, high reactivity between Al and moisture often leads to the generation of hydrogen (H) atoms at elevated temperatures, resulting in hydrogen embrittlement. In this study, a thin Ni layer of approximately 0.5 μm in thickness was electroplated on the steel substrate surface before the conventional AlSi coating process. The formation of a Ni-enriched zone was found to affect hydrogen intrusion and emission behavior positively. Prior to the HPF simulation, the Ni-enriched zone was formed inside Fe2SiAl7 intermetallic compounds, and migrated toward the outer FeAl(Si) layer during the subsequent HPF simulation. This migration served as an impediment to elemental diffusion, thereby resulting in a prolonged simulation time for the complete formation of coating microstructures. Consequently, the presence of the Ni-enriched zone functioned as a high-energy barrier, impeding the diffusion of H and rendering H intrusion more challenging, while simultaneously enhancing corrosion resistance. Complete H emission occurred within 3 days in the Ni-precoated sheet, whereas a significant amount of H content remained even after 17 days in the non-Ni-precoated sheet. This difference could be attributed to the reduced amount of H intrusion in the Ni-precoated sheet, despite similar H emission rates observed in both sheets.

Molecular dynamics and first-principles calculations on the wetting behavior and mechanism of molten Al on nickel-infiltrated steel: A cross-scale simulation

Wetting behavior and mechanism of melting Al on Ni-infiltrated steel were investigated using the cross-scale simulations. The molecular dynamics calculations were employed firstly to intuitively exhibit the influence of amount of nickel infiltration (on the surface of steel substrate) on wettability of Al droplet. The micro-mechanisms affecting wettability, such as the bonding characteristic and charge distribution on wetting interface, were researched using the first-principles calculations. The results indicate that, the chemical reactions occur on Al droplets/Ni-infiltrated steels wetting interfaces. With the increasing amount of Ni infiltration, the main interfacial intermetallic compound (IMC) transforms from Fe2Al5 to NiAl and finally to Ni3Al. Although the atomic bonds on Al/Fe2Al5, Al/NiAl, and Al/Ni3Al interfaces all show both ionic and covalent characteristic, the work of adhesion for the three Al/IMC interfaces follows the order of Al/Fe2Al5 > Al/NiAl > Al/Ni3Al. This phenomenon indicates that the interfacial bonding strength between Al droplet and the generated IMC decreases gradually with the increasing amount of Ni infiltration, and leading to the improving wettability because the wettability is negatively correlated with the Al/IMC bonding strength on wetting interface.

Microstructure and Mechanical Properties of Fe-Based Alloy Coatings Fabricated by Laser Cladding

The Fe-based alloy coating was prepared on the surface of 25Cr2Ni4MoV steel substrate by laser cladding. The microstructure, microhardness, shear strength, friction and wear properties of the laser cladding coating were systematically studied. The results show that a good metallurgical bond has been formed between Fe-based alloy coating and substrate. The laser cladding layer is a typical dendritic crystal, which is composed of light gray and dark gray phases. The shear strength displacement curve shows the typical characteristics of brittle fracture, with an average shear strength of 280.83 MPa. The average dry friction coefficient, wear track depth and average wear volume of laser cladding Fe-based alloy coatings are (0.45 ± 0.01), (26 ± 3) μm and 0.066615 m3, respectively. The average dry friction coefficient, wear track depth and average wear volume of 25Cr2Ni4MoV substrate are (0.60 ± 0.01), (39 ± 3) μm and 0.13085 m3, respectively. The laser cladded Fe-based alloy coating exhibits much better wear resistance than the steel substrate, and the shear strength of the coating displays its potential for the application in the service environment of shear stress.

Effect of CeO2 on the microstructure and properties of AlCoCrFeNi2.1 laser cladding coatings

In the process of strengthening the substrate’s surface properties, it is easy to produce cracks or air holes and other defects between the coatings and the substrate, and rare earth elements can improve the microstructure and properties of the metal surface coatings. Using laser cladding(LC) technology, the effect of the addition of rare earth oxides CeO2 on the properties of AlCoCrFeNi2.1 coatings is investigated to find the optimal amount of CeO2 added. AlCoCrFeNi2.1 alloy powder doped with Xwt% (X = 0–3) rare-earth oxide CeO2 was clad on the surface of the H13 steel substrate by laser cladding process using RFL-C3000 laser. The macroscopic morphology, microstructure, hardness, and corrosion resistance of specimens were analyzed and studied by optical microscope (OM), scanning electron microscope (SEM), X-ray diffractometer (XRD), hardness tester, and other equipment. The results show that the addition of the appropriate amount of rare earth oxide CeO2 (3 %) can effectively reduce the cracks, air holes, and inclusions in the composite layer, and promote grain refinement. The addition of 3 wt%CeO2 to AlCoCrFeNi2.1 can improve the microstructure uniformity and surface hardness of the coatings, and significantly improve the wear and corrosion resistance of the composite coatings.

Microstructure and Properties of Inconel 718 Coatings with Different Laser Powers on the Surface of 316L Stainless Steel Substrate

Laser cladding is a new method to prepare coatings with good quality. Laser power is one of the main factors affecting the quality of laser cladding coatings. An appropriate laser power helps obtain a high-performance laser cladding coating. In order to obtain coatings with good quality, an experiment with different laser powers was designed in this research. Three Inconel 718 coatings with different laser powers were prepared on the surface of a 316L stainless steel substrate. And the effect of different laser powers (1400, 1600, and 1800 W) on the microstructure, phases, and element distribution of coatings (L1–L3) was investigated by SEM, EDS, XRD, and a wear and friction tester. Meanwhile, the microhardness and friction and wear properties of different coatings were analyzed. The results show that the coatings’ phases were the same and composed of γ~(Fe, Ni) solid solution, Ni3Nb, (Nb0.03Ti0.97)Ni3, MCX (M = Cr, Nb, Mo), and so on. The background zones in the L1–L3 coatings were mainly the Fe and Ni elements. The irregular blocks in the coating were rich in Cr, Mo, and Nb, which formed the MCX (M = Cr, Nb, Mo) phase. When laser powers were 1400, 1600, and 1800 W, the average microhardness of the three coatings was 685.6, 604.6, and 551.9 HV0.2, respectively. The L1 coating had the maximum microhardness, 707.5 HV0.2, because the MCX (M = Cr, Nb, Mo)-reinforced phase appeared on the upper part of the coating. The wear rates were 3.65 × 10−5, 2.97 × 10−5, and 6.98 × 10−5 mm3·n−1·m−1. The wear mechanism of the three coatings was abrasive wear and adhesive wear. When the laser power was 1600 W, the coating had the minimum wear rate, which exhibited the best wear resistance. When the laser power was 1600 W, the upper part of the coating to the bonding zone was mainly composed of equiaxed crystals, dendrites, cellular crystals, columnar crystals, and planar crystals. The fine crystals and compounds caused a decrease in wear volume, and they had the most optimal wear resistance.

Enhancing tribological performance of graphene sheet-embedded carbon films on steel substrates via texture engineering and chromium doping

Amorphous carbon (a-C) film is a promising solid lubricant coating due to its unique structure and excellent properties. However, its poor adhesion and long running-in period hinder the application in metal components. Graphene sheet-embedded carbon (GSEC) film has a significantly shorter running-in period but suffers from inferior tribological properties due to its rough surface and weak mechanical characteristics. In this study, we utilized an electron cyclotron resonance (ECR) plasma nano-surface manufacturing device to deposit GSEC films onto steel substrate surfaces. By manipulating the surface/interface texture and incorporating chromium (Cr) doping, the tribological properties of the GSEC films were improved both chemically and physically. The results demonstrated that the textured carbon film exhibited superior adhesion to the steel substrate and a wear life that was three orders of magnitude longer than the untextured GSEC film, under low normal load conditions while sliding against the GCr15-bearing steel ball. After doping the Cr into textured carbon films, there was a significant reduction in the friction coefficients, and the wear type of carbon film transformed from adhesive wear to abrasive wear. Moreover, the doped carbon films demonstrated prolonged wear lives under high normal loads. This improvement can be attributed to the formation of hard CrC nanocrystalline, which effectively reduced surface roughness and enhanced the mechanical properties of the carbon films. Notably, even under a contact pressure of 0.83 GPa, the doped carbon film maintained favorable tribological performances. These findings have extended the potential applications of carbon films on metal substrates.

Mathematical methods in studying temperature-time conditions of the friction surfacing in the manufacture of functionally organized steel-aluminum compositions

A mathematical model for studying temperature and time conditions of the process of friction surfacing in the manufacture of functionally organized steel-aluminum compositions has been developed and validated. Bars made of pure aluminum grade ER1100 were used as the consumable rod material during friction surfacing. The substrate in the form of a rectangular plate was made of high-quality steel 20. The geometric model of the object when modeling the process of friction surfacing in the ANSYS 2021R2 software package was specified in the form of a rod and a substrate. The initial data for calculating temperature-time conditions of the friction surfacing process are: geometric parameters of the simulation object; characteristics of thermal loads of the heating source which depend on the technological parameters of the surfacing mode (the speed of axial rotation of the rod, axial pressure, boundary conditions of the simulation object for the temperature problem), and auxiliary parameters that determine the order of calculations. The thermal power arising at the point of physical contact between the rotating consumable rod and the substrate was considered a parameter of the source thermal load. The calculation of heat propagation for the friction surfacing process was carried out according to a scheme with a normally circular source located on the substrate surface. The calculation scheme directly reflects the main feature of the friction surfacing process: the introduction of heat due to friction between the rotating consumable rod and the substrate. It is shown that taking into account the boundary conditions and geometric features of the 3D model provide a satisfactory convergence of developed mathematical model and ensure the uncertainty of no more than 5 % in determining the heating temperature of the substrate when forming functional aluminum coatings, as well as composite materials on their base when surfacing them on the surface of steel substrates.

Investigation of Corrosion Properties and Composition of the Surface Formed on AISI 321 Stainless Steel by Ion Implantation

In this work, the corrosion resistance of AISI 321 stainless steel is increased through. the two-stage implantation of oxygen ions and of both aluminum and boron ions together. During ion implantation, a modified layer with a thickness of about 200 nm is formed, which affects the properties of material. The increase in corrosion resistance is confirmed by prolonged acid corrosion tests at pH 3.5 and by accelerated electrochemical tests using a potentiostat. The corrosion rate of the implanted sample is 0.708 μA/cm2, in contrast to the non-implanted sample (1.26 μA/cm2). The modified surface layer is examined using X-ray photoelectron spectroscopy (XPS), secondary-ion mass spectrometry (SIMS), and transmission electron microscopy (TEM). Aluminum and boron are implanted to a depth of more than 250 nm. It is found that the modified surface of the stainless steel substrate contains oxides of implanted ions (Al2O3) and oxides of substrate ions (Cr2O3 and NiCr2O4).

Re-healing of separated steel substrate and work-hardened surface layer in roll-bonded steel–aluminum laminates

Roll bonding is ideal for preparing metallic composite laminates (MCLs). When MCLs are prepared by roll bonding, a work-hardened surface layer (WHSL) is typically prepared on the plate surface to promote bonding. However, differences in the mechanical properties of the WHSL and substrate lead to the WHSL separated from steel substrate during roll bonding, resulting in low bonding strengths of the roll-bonded laminates. This study focused on steel–Al laminates to successfully heal the cracks between the WHSL and the steel substrates via heat treatment. The crack-healing mechanism, element diffusion behavior, bonding property, and fracture morphology of the laminates were investigated. The results show that after roll bonding, the WHSL of the steel surface was separated from the steel substrate, and the steel–Al laminates exhibited a lower bonding strength. After annealing the laminates with cracks between WHSL and steel substrate at 450 °C for 60 min, a 426.8 nm Fe2O3 layer was generated between the WHSL and the steel substrate, healing the cracks. Additionally, good connectivity was observed between the WHSL and steel substrate. The shear strength of the steel–Al laminates increased by 1.7 times after the formation of the Fe2O3 layer. Analysis of the fracture morphology showed that shear fracture primarily occurs at the interface between the WHSL and steel substrate before the formation of the Fe2O3 layer; after the Fe2O3 layer is formed, shear fracture primarily occurs in the aluminum substrate. This study provides a new strategy for improving the bonding strength of roll-bonded steel–Al laminates.