Electron Beam Cladding Research Articles

Structure and oxidation behavior of CoCrFeNiX (where X is Al, Cu, or Mn) coatings obtained by electron beam cladding in air atmosphere

High-entropy alloys (HEAs) are currently considered as promising materials for a wide range of applications, including high-temperature use. Since HEAs contain a large number of expensive elements, producing HEA-based coatings seems to be a reasonable approach from an economic point of view. In this study, non-vacuum electron beam cladding was used for the first time to produce CoCrFeNiX layers (where X = Al, Cu or Mn) on a surface of low-carbon steel. As-received coatings had a columnar grain structure with a 〈100〉 fiber texture. The CoCrFeNiCu cladding layer consisted of two fcc phases: Cu-enriched phase was observed in the interdendritic regions, and the Cu-depleted phase was found in dendrites. The CoCrFeNiMn coating had a single-phase fcc structure. CoCrFeNiAl alloy consisted of bcc and B2 phases. The hardness of the Cu and Mn-containing coatings was 190 and 186 HV, respectively. The hardness of the CoCrFeNiAl coating was 570 HV, which is 3.4 times higher compared to the material of the substrate. High-temperature oxidation tests carried out at 850 °C for 45 h revealed that oxide layers formed on the tested samples had a gradient structure that consisted of several different sublayers. The total mass gain due to high temperature oxidation was 2.29 mg/cm2, 2.04 mg/cm2, and 0.60 mg/cm2 for the CoCrFeNiCu, CoCrFeNiMn, and CoCrFeNiAl samples, respectively. The mass gain of the base material over the same period of time was 41.01 mg/cm2. The CoCrFeNiAl coating had the best oxidation resistance due to the formation of a dense Al2O3 scale. We show that non-vacuum electron beam cladding can be used to produce an HEA-based coating with a different chemical composition. The thickness of coatings in a single pass cladding can be as high as 1.8 mm. CoCrFeNiAl is a suitable coating for low-carbon steel in applications where high hardness and oxidation resistance are required.

Effect of WC-10Co on microstructure and properties of medium-entropy alloy coatings via electron beam cladding

In this study, non equiatomic FeCrNiCoMoW MEA composite coatings were successfully prepared by electron beam cladding Fe-based amorphous powders. The effects of WC-10Co amounts (0–30 wt%) on the microstructure, mechanical properties, and electrochemical property of the MEA composite coatings were investigated. The added WC-10Co decomposed, and the original amorphous alloy was completely crystallised. The composite coatings primarily comprised the face-centred cubic (FCC) matrix, M23C6 (M = Cr, Mo, Fe, or W) and WC particles. The average hardness of the composite coatings gradually increased with increased WC-10Co amounts from 5.66 ± 1.09 GPa to 8.02 ± 2.54 GPa. The composite coating with 30 wt%WC-10Co showed optimal hardness and wear resistance, which were approximately 4 and 2 times that of the substrate, respectively. The wear mechanism changed from severe adhesive wear for 0 wt% WC-10Co composite coating to abrasive and slight adhesive wear for 10–30 wt% WC-10Co composite coatings. The 10 wt% WC-10Co coating exhibited the best corrosion resistance in 3.5 wt% NaCl solution. The number of corrosion pits decreased with the addition of WC-10Co increased, and corrosion occurred in the Cr-depleted regions. Solid solution, dislocation, WC particles and M23C6 nanoprecipitates were responsible for the improvement in mechanical properties and corrosion resistance of the coatings.

Mo20Nb20Co20Cr20(Ti8Al8Si4) refractory high-entropy alloy coatings fabricated by electron beam cladding: Microstructure and wear resistance

The refractory high-entropy alloys (RHEAs) possess excellent mechanical properties and electron beam cladding (EBC) has the advantages of vacuum protection and higher energy utilization. In this study, the Mo20Nb20Co20Cr20(Ti8Al8Si4) RHEA coatings under different cladding currents (16, 17, 18,19 mA) are fabricated by EBC to improve the surface wear resistance of the Ti600 substrate. The microstructure and phase structure of RHEA coatings are investigated by OM, SEM, XRD, TEM. The mechanical properties of tcoatings and substrate are studied by microhardness, nanoindentation and dry wear test. The results show that the HEA coatings involve four main phases: BCC1(Mo,Nb,Al-rich-A2/B2), BCC2(Co,Cr,Ti-rich-B2), IMC1(Laves phase-CoTi) and IMC2((Ti,Nb,Zr)5Si3), respectively. With the cladding current increasing, the dilution rate of the substrate increases to cause the Ti content within coatings to rise. The size of BCC1(DR regions), IMC1 and IMC2 becomes larger and the microhardness, nanoindentation hardness, elastic modulus and room-temperature creep resistance decrease. The properties improvement of the coating is attributed to the solid solution, second phase and precipitation strengthening caused by the solid solution structures and intermetallic compounds. The maximum microhardness of the coatings at current 16 mA is 1150 HV0.2, more than 3 times that of the substrate and the friction coefficient of Ti600 is 2.16 times that of current 16 mA, which suggests that the Mo20Nb20Co20Cr20(Ti8Al8Si4) RHEAs can be used as an excellent wear-resistant coating with broad application prospect.

Development of a basic technology for multilayer electron beam cladding of Inconel 718 nickel-based alloy onto an austenitic stainless steel

Within the scope of the investigations, experiments were performed for single-bead and flat overlapping wire-based electron beam cladding (EBC) of the nickel-based alloy Inconel 718 onto the austenitic stainless steel AISI 347. The focus was on the influence of process parameters such as the wire feed rate, wire feed direction, electron beam energy input and the degree of overlap on the formation of the cladding layer in terms of microstructure, geometry, hardness and chemical composition, as well as the number of defects occurring. As a result, a suitable parameter set was identified for multilayer, defect-free cladding.

Analysis and Control of Cracks in Ni60 Coating of 7050 Aluminum Alloy by Electron Beam Cladding

Ni60 electron beam cladding can play an important role in improving the properties of 7050 aluminum alloy. The cracking of the cladding layer, however, greatly affects the cladding quality. To solve this problem, the optimum range of cladding process parameters is determined by an experimental method: electron beam current [25–30 × 10−3 A], scanning speed [10–12 mm/s] and focusing current [700–720 × 10−3 A]. Through range analysis of the experiment results, the primary and secondary order of the influence of the cladding process parameters on the crack areal density is determined as follows: electron beam current > scanning speed > focusing current. A mathematical model of the crack areal density of the cladding layer is established based on the method of nonlinear regression, which is y = 4.1553 × 104 I2.2887V−0.8379I210.2675. It is shown that the model has obvious significance in the results of variance analysis, which can provide a basis for the selection of electron beam cladding process parameters.

Effect of Pre-Set Coating Thickness on the Quality of Electron Beam Cladding Forming of Aluminum Alloys

Numerical simulations combined with electron beam melting were adopted to study the effect of the thickness of the preset coating on the quality of electron beam melting and forming of aluminum alloys. The research was carried out using ANSYS19.0 finite element analysis software to perform the numerical simulation of the temperature field and stress field during the process of electron beam melting of the Ni60 coating on 6061 aluminum alloy. The results show that the thicker the preset coating, the higher the surface temperature and the greater the melting depth and width of the melt pool, but the smaller the substrate melting depth, and the highest surface temperature obtained was 2536.05 °C. When the coating thickness reached 1.5 mm, the substrate essentially showed no change; otherwise, the thicker the preset coating, the greater the residual stress, and the maximum residual stress on the coating surface along the scanning direction appeared at the position near the boundary. Moreover, the maximum residual stress along the depth direction occurred at the interface. The electron beam cladding experiments showed that the 0.5 mm thickness of the coating resulted in a cracking phenomenon at the interface with the substrate, and the surface of the molten layer had more defects such as pores and pits; the 1 mm thickness of the coating had a good metallurgical bond with the substrate, and the surface of the molten layer was dense and flat; the 1.5 mm thickness of the aluminum alloy substrate did not melt, and the surface of the molten layer had more cracks. The numerical simulation was essentially consistent with the electron beam cladding experiment, and the forming quality was better when the preset coating thickness was 1 mm.

Use of Non-Vacuum Electron Beam Cladding for Creating a Combined Joint of High-Carbon and Chromium-Nickel Steels

Use of Non-Vacuum Electron Beam Cladding for Creating a Combined Joint of High-Carbon and Chromium-Nickel Steels

Corrosion Resistance of Materials Obtained By Electron-Beam Cladding of Fe – Cr – Ni – Ti Powder Mixtures

Corrosion Resistance of Materials Obtained By Electron-Beam Cladding of Fe – Cr – Ni – Ti Powder Mixtures

Structure and Properties of Surface Layers Obtained Via Nonvacuum Electron-Beam Cladding with Copper and Boron Powder Mixtures

Structure and Properties of Surface Layers Obtained Via Nonvacuum Electron-Beam Cladding with Copper and Boron Powder Mixtures

Plastic Strain Localization in Steel Composites Produced via Additive Manufacturing

In this work we report the kinetics of plasticity of St3 low-carbon steel-based composite alloy prepared via vacuum electron beam cladding of 09G2S steel wire. The digital image correlation method revealed the existence of macroscopic localization of plastic flow at the yield plateau and parabolic hardening stage. The kinetic characteristics of localized plasticity domains were measured in various composite layers, as well.

Structural Features of Ni-Based Self-Fluxing Alloy Protective Layers, Produced by Non-Vacuum Electron Beam Cladding, Reinforced with Titanium-Based Particles

The aim of this research was to establish influence of Ti-enriched powder mixtures on structure and microhardness level of protective layers based on Ni-Cr-Si-B-alloy, produced with non-vacuum electron beam cladding technology. The fabricated protective layers possessed the complex structure, consisting of matrix phase (γ-(Ni, Fe)) combined with hard phases such as Fe2B, CrB and TiC. Addition of titanium with boron in amount of 15 wt. % leads to significant increasing of microhardness level. In this case, level of microhardness increases up to 700 HV.

Oxidation Resistance of “Ni-Cr-Si-B-Alloy + Nb + B” Protective Layers, Produced by Non-Vacuum Electron Beam Cladding Technique

The aim of this investigation was to study the influence of Nb-enriched powder mixtures on structure and oxidation resistance of protective layers based on Ni-based self-fluxing alloy, produced by non-vacuum electron beam cladding technique on low-carbon steel substrates. The oxidation resistance of coatings was studied by thermogravimetric analysis (TGA). The samples held at 900°C for two hours in air atmosphere. TGA results indicate that the highest oxidation resistance has the material, obtained by cladding of pure Ni-based self-fluxing alloy. Samples, produced by cladding of Ni-based self-fluxing alloy in combination with Nb-enriched powder mixtures demonstrate lower level of oxidation resistance. Structure of the coatings was characterized by optical and scanning electron microscopy combined with electron microprobe analysis as well as X-ray diffraction.

Microstructure and wear behavior of AlCrTiNbMo high-entropy alloy coating prepared by electron beam cladding on Ti600 substrate

High-entropy alloys have been widely studied as a new and excellent material in the field of surface protection. To improve the low surface hardness and wear resistance of Ti600 alloy, AlCrTiNbMo high-entropy alloy (HEA) coating was prepared by electron beam cladding. The phase structure and microstructure showed the presence of two BCC solid solution phases A2 and B2 within HEA coating. Laves phase Ti3Al and intermetallic compound Mo3Al8 were also present in the coating. The results of hardness and wear resistance tests showed that the microhardness of coating is 813.5 HV0.2，while substrate is 370.7 HV0.2. The mass loss of coating is only 1.02 mg after wear test, while the mass loss of Ti600 is 38.81 mg. There are cracks and delaminations on the worn surface of Ti600, and wear mechanism is a mixture of micro-ploughing and micro-cutting. The worn surface of HEA coating contains only shear surface traces, and the wear mechanism is micro-cutting. The width and depth of grooves on the worn surface of HEA coating are nearly 10 times that of Ti600 substrate. AlCrTiNbMo HEA coating can be used as an excellent wear-resistant coating with wide application prospect.

Study on the Solidification Behavior of Inconel617 Electron Beam Cladding NiCoCrAlY: Numerical and Experimental Simulation

To better control the Inconel617 electron beam cladding solidification process, a three-dimensional temperature field model was built to simulate the temperature gradient, cooling rate, and solidification rate in the solidification process and take a deep dive into the solidification behavior, as well as the calculation of the solidification characteristic parameters at the edge of the molten pool and then predict the solidification tissue structure. The study shows that the largest temperature gradient occurred in the material thickness direction. The self-cooling effect of the material dominated the solidification of the alloy layer; the cooling rate depended on the high-temperature thermal conductivity of the material and the self-cooling effect of the matrix, and the maximum cooling rate in the bonding zone was 1380 °C/s. The steady-state solidification rate was equal to the moving speed of the heat source; the solidification characteristics of the solidification process at the edge of the molten pool increased with the distance from the surface: the cooling rate decreased from 1421.61 to 623 °C/s, the temperature gradient increased from 0.0723 × 106 to 0.417 × 106, and the solidification rate decreased from 0.01 to 0 m/s. The prediction was made that the small and thin equiaxed crystals are on the top, a thin and short dendritic transition structure in the middle, and relatively coarse dendrites at the bottom. Experiments confirmed that the solidification tissue structure is basically consistent with the simulation law.

Microstructure and properties of multilayer WC-40Co coating on Ti-6Al-4V by electron beam cladding

Single, double, and triple-layer WC-40Co coatings were prepared by electron beam (EB) cladding to improve the wear resistance of Ti-6Al-4V. The microstructure, microhardness, wear resistance, and corrosion resistance of the coatings were investigated. The results demonstrated that the three types of coatings consisted of β (Ti, W), TiCo, (Ti, W) C1-X, (W, Ti) C1-X, and a small amount of Ti2Co. The core/shell structure of (W, Ti) C1-X/ (Ti, W) C1-X was observed by TEM, and the phase interfaces were studied. The hardness and wear resistance of triple-layer coating was the highest, and its wear resistance was improved by 11.5 times that of the substrate. The wear mechanisms of the substrate, single- and double-layer coating was oxidative and abrasive wear, while the triple-layer coating exhibited abrasive wear. The corrosion resistance of the single- and double-layer coatings was better than that of the substrate; however, the triple-layer coating surface was significantly damaged owing to the cracks.

Microstructure and properties of WC-Ni3Al composite coatings fabricated by non-vacuum electron beam cladding

The non-vacuum electron beam cladding technique was used to fabricate composite coatings with WC on the surface of Ni3Al intermetallic. The microstructure and phase composition of composite coatings were studied using scanning electron microscopy, energy dispersive X-ray analysis, and X-ray diffraction analysis. The results showed a good metallurgical bond of WC particles with the Ni3Al intermetallic matrix. Addition of CaF + LiF flux mixtures in the initial cladding powder reduces the loss of tungsten carbide powder compared to MgF2 flux during electron-beam processing. Effect of tungsten carbide volume fraction, particle size and shape on the microhardness, wear mechanism of composite coatings was demonstrated. The microhardness of produced composite coatings was 1.3–1.5 times higher than substrate material and wear resistance was 2.2 times higher than Ni3Al.

Microstructure characterization and wear performance of WC-10Co/Ti-6Al-4V coating fabricated via electron beam cladding

In this study, WC-10Co/Ti-6Al-4V coatings were fabricated under varying cladding voltages via electron beam cladding technology. The microstructure, microhardness , and wear performance of the composite coatings were studied. In addition, temperature field simulations were performed for the cladding process applying ABAQUS. The thickness of the coatings ranged from 350 to 850 μm. The presence of α-Ti, (Ti, W)C 1-X , and small amounts of WC, TiC, (W, Ti)C 1-X , W 2 C, and β-Ti in the coatings was confirmed. WC and TiC were partially dissolved and, in accordance with the simulated temperature field, resulted in the appearance of (W, Ti)C 1-X around the WC particles. Moreover, the consumption of C atoms was beneficial for the diffusion of W atoms into the TiC lattice to form (Ti, W)C 1-X . In the comparison of experimental and numerical simulation results, it was found that a deeper penetration and further settlement of WC particles was observed experimentally, when a higher cladding voltage was applied. The coating prepared under 65 kV exhibited the best mechanical performance and its friction mechanism entailed abrasive and adhesive wear . • WC-10Co/Ti-6Al-4V composite coatings were fabricated via electron beam cladding. • Microstructures of the coatings were characterized. • Formation mechanisms of (Ti, W)C 1-X and (W, Ti)C 1-X were investigated. • The coating fabricated at 65 kV exhibited best wear resistance performance.

Influence of different pre‐surface treatments using electron beam and subsequent boriding on tribological and corrosive load behaviour – Part II

AbstractIn order to make cast iron usable for highly stressed components or tools, the duplex treatment of electron beam (EB) remelting or cladding using a nickel‐based additive (a supporting layer without graphite) and boriding (a functional layer) is considered to have extraordinarily high potential for realizing the necessary division of functions. Due to the high process temperatures during boriding, the electron beam‐treated layers should have sufficient thermal resistance to fulfil the required supporting function for the boride layers. However, this could only be confirmed for the cladded layers. This paper deals with comparative investigations on the effects of single and combination treatments performed on the cast iron surface on the material's wear (dry pin‐on‐disc tests) and corrosion behaviour (potentiodynamic measurements in an aerated sodium chloride solution and in sulphuric acid). After testing, and in particular in terms of corrosion resistance, the duplex treatment of electron beam cladding+boriding showed a clear improvement over single treatment. With regard to wear performance, however, only a marginal improvement could be determined. This was highly dependent on the boride layer thickness and the loading conditions.

Structure and Properties of Ti-Al-Ta and Ti-Al-Cr Cladding Layers Fabricated on Titanium

Being one of the most high-demand structural materials, titanium has several disadvantages, including low resistance to high-temperature oxidation and wear. The properties of titanium and its alloys can be improved by applying protective intermetallic coatings. In this study, 2 mm thick Ti-Al-Ta and Ti-Al-Cr layers were obtained on titanium workpieces by a non-vacuum electron-beam cladding. The microstructure and phase compositions of the samples were different for various alloying elements. The Cr-containing layer consisted of α2, γ, and B2 phases, while the Ta-containing layer additionally consisted of ω′ phase (P3¯m1). At the same atomic concentrations of aluminum and an alloying element in both layers, the volume fraction of the B2/ω phase in the Ti-41Al-7Ta alloy was significantly lower than in the Ti-41Al-7Cr alloy, and the amount of γ phase was higher. The Ti-41Al-7Cr layer had the highest wear resistance (2.1 times higher than that of titanium). The maximum oxidation resistance (8 times higher compared to titanium) was observed for the Ti-41Al-7Ta layer.

Effect of refractory modifiers on the structure of coatings based on chromium carbide

Chromium carbide-based coatings with and without TiC and TiB2 modifiers were fabricated by non-vacuum electron-beam cladding. Addition of the modifiers to the initial Cr3C2 powder mixture led to a change in the phase composition, microhardness and wear resistance of the composite coatings and the α → γ transformation of Fe. TiC and TiB2 particles formed the many crystallization centers in composite coatings, which led to a refinement of their microstructure. Larger TiC particles compared to the TiB2 particles were formed in the coatings as a result of melt crystallization. TiC modifier caused a decrease in the size of dendrites, while TiB2 led to a transition from a coarse dendritic structure to an equiaxed one. The coatings with TiC modifier demonstrated the maximum microhardness, and TiB2 coating had increased wear resistance.