Non-vacuum Electron Beam Research Articles

Influence of the Ti/Al/Nb ratio on the structure and properties on intermetallic layers obtained on titanium by non-vacuum electron beam cladding

Ti-Al-Nb based intermetallic layers of sufficient quality and thickness were obtained by non-vacuum electron beam cladding on the surfaces of Ti workpieces. Optical microscopy and X-ray tomography did not reveal any dramatical defects in the structure of cladded layers. X-ray diffraction as well as scanning and transmission electron microscopy were applied to thoroughly investigate the structure and phase composition of coatings. It was found that non-equilibrium cooling conditions of coatings provided by fast removal of heat to untreated Ti substrate after the electron beam cladding was terminated induced the proceeding of metastable phase transformations. For example, γ-phase formation was suppressed in these coatings. In coatings with 8 and 20 at.% Nb (46 and 43% Al respectively) along with ordered with α2, formation of disordered solution of the alloying elements in α-Ti took place. In high-Nb alloys β(B2) phase has undergone the diffusionless transformation to ω’, which is the intermediate phase in β → ω and the coating with the maximum Nb content characterized by appearance of γ1 as a main phase. ω-phase had negative influence to hardness and wear resistance of coatings, however, generally this paremeter increased in 1.3–1.75 times compared to cp-Ti. The high temperature creep and oxidation properties decreased proportionally with increasing Nb and decreasing Al content in the cladded layers.

Corrosion and Wear Resistance of Coatings Produced by Nonvacuum Electron Beam Cladding of Refractory Carbides on Low-Carbon Steel

Using nonvacuum electron beam cladding of a Cr3C2 + TiC powder mixture, we have produced coatings on low-carbon steel in a wide range of processing conditions. The coatings and reference samples have been tested in corrosion and wear resistance. The results demonstrate that the coating obtained at a deposited surface energy density W = 8.8 kJ/cm2 has the highest corrosion resistance, which is due to the increase in the chromium concentration in the cladded layer to 16%. The wear resistance of the coatings has been shown to be influenced by the number and size of titanium carbide particles. The highest wear resistance is offered by the coating produced at W = 10.0 kJ/cm2.

Wear-resistant boride reinforced steel coatings produced by non-vacuum electron beam cladding

In this work, we present a wear-resistant coating fabricated by non-vacuum electron beam cladding of Fe62Cr10Nb12B16 at.% powder on a mild steel substrate. The protective coating was 1.3 mm thick, dense, and exhibited an α-(Fe,Cr) matrix reinforced by a significant fraction of hard borides formed upon solidification. Micrometric and nanometric borides homogeneously dispersed within the matrix were formed due to the homogeneous melting and the relatively fast cooling to suppress the excessive phase growth. An intimate metallurgically bonded interface between the coating and substrate was characterized by low compositional dilution and a fine eutectic-like transition zone microstructure anchoring the dissimilar materials. The coatings displayed a higher wear resistance compared to the mild steel substrate, showing specific wear rates, κ, about one order of magnitude lower (10−5 against 10−4 mm3/N.m, respectively). The abrasive wear mechanism was dominant for the coating sample when tested at low sliding velocity, 10 cm/s, due to the detachment of hard borides from the surface and their incorporation into the tribosystem. The adhesive wear mechanism was found to be dominant at higher sliding velocities of 20 and 40 cm/s. Dry sand/rubber wheel testing revealed the higher resistance of the coating against abrasive wear compared to the mild steel substrate. Regardless of the wear mechanism, the Fe62Cr10Nb12B16 at.% coatings showed a superior sliding and abrasive wear resistance and represented an interesting protective measure to extend the service of inexpensive mild steel components.

Non-vacuum electron beam welding and cutting of cupper

Due to its physical properties, like high thermal and electrical conductivity copper is an indispensable material in many branches of industries. However the welding and cutting of copper and its alloys is challenging due to this properties and tendency to absorb gases resulting some defects like porosity or hot cracking. To prevent these, different requirements concerning the welding process have to be fulfilled. One requirement is the use of a highly concentrated heat input. The electron beam in atmosphere (NVEBW)is a suitable tool, which meets this requirement. This publication presents the advantages of NVEBW welding and cutting of copper. The experimental results of low-voltage (NVEBW) of copper will be shown and discussed too. The first portion studied the effects of varying power, travel speed and work distance on mechanical and electrical properties and structure of weldment at 175 kV accelerating voltage. The second portion studied the possibility of application of low-voltage 60kV NVEBW for welding of copper and influence of impurities in the copper on the welding parameters. The third portion studied the process of NVEB cutting of copper using the suction created by a local vacuum underneath the work piece. Experimental results of cutting with extremely high cutting speeds such as15m/min for 1.5 mm thick and 9m/min for 6mm thick copper will be representing.

Modelling of heat transfer process in non-vacuum electron beam additive manufacturing with CuSi3 alloy wire

Non-vacuum electron beam wire feed deposition is a new technology in the family of additive technologies. It has some advantages in comparison with the laser one, especially for materials with great reflection ability, such as copper alloys. The suggested model is for assist determination of the optimal modes of processing. It considers heat transfer processes in the substrate and wire and also surface formation of the deposited layers. A wire can be feed along the process direction as well as from a side position. The equation of the liquid phase equilibrium in the gravity field is used to analyze the mechanism of formation of the bead surface profile. The proposed method allows determining the shape of the wall surface of the product with satisfactory accuracy. The position of the wire tip greatly affects both the shape and the size of the melt pool and its temperature. Increasing the wire feed rate leads not only to an increase in the cross-sectional area and the height of the deposited layers but also to a decrease in the width of the wall. Therefore, special attention should be paid to the selection of the wire feed rate.

Влияние термической обработки на свойства композиционных покрытий, полученных электронно-лучевой наплавкой вне вакуума

The effect of heat treatment on the structure and properties of composite coatings based on chromium carbide with titanium carbide fabricated by non-vacuum electron beam cladding without has been studied. It was shown that tempering leads to a decrease in microhardness and wear resistance, which is associated with the decomposition of the austenitic structure with the formation of a soft ferrite-carbide structure. The post heat treatment tempering was showed to decrease of microhardness and wear resistance, which leads to the decomposition of the austenitic structure with the formation of a soft ferrite-carbide structure. The bulk quenching of coatings after tempering leads to an increase in microhardness comparable to the values of microhardness in the initial state after electron beam cladding, due to the formation of high hard martensite. The wear resistance of composite coatings after tempering is lower than after cladding due to brittle martensite, which is not able to hold solid carbide particles. The composite coatings obtained at the optimal processing conditions have a combination of improved properties and do not require additional heat treatment, resulting in structural changes, causing a decrease in mechanical properties.

A System for Extracting an Electron Beam into the Atmosphere Based on a Plasma Emitter Gun

The main characteristics and schematic of a device for extracting a focused electron beam into the atmosphere are described for a gun with a plasma emitter. It is shown that guns with a plasma emitter can be used to produce zinc oxide powders with particle sizes of around 100 nm in the atmosphere. Results are presented from the nonvacuum electron beam deposition of coatings based on carbides of refractory metals. The possibility of welding aluminum and copper parts with an electron beam at atmospheric pressure is demonstrated.

Determination of mechanical properties of coatings obtained by non-vacuum electron beam cladding

A study on the mechanical properties of composite materials obtained by the method of non-vacuum electron-beam cladding of refractory powders on a steel substrate was carried out. The mechanical properties of composite with coatings were investigated by a three-point bending test at room temperature. The strength of the obtained composite was 4.5-6 times higher compared to that of low carbon steel depending on the deposition modes.

Corrosion Resistance of Medical Stainless Steel Obtained by Non-Vacuum Electron Beam Cladding

Pitting and crevice corrosion resistance of 321 stainless steel and non-vacuum electron-beam cladded stainless steel have been investigated by using potentio-dynamic polarization curve plotting. Lock-Ringer Salt Solution (LRSS) was used as biological media for corrosion test measurements. Microstructural research of samples after corrosion was carried out by using scanning electron microscopy. The experimental results show that the cladded stainless steel possesses higher pitting and crevice corrosion resistance.

Non-Vacuum Electron Beam Cladding of Ti-Ni-Al Intermetallics on Titanium Alloy

In this study intermetallic coatings were formed on the surface of Ti-6Al-4V alloy by electron beam emitted into the air atmosphere. Optical and electron scanning microscopy, X-ray diffraction and EDX analysis were used to investigate the structural features of material. The powder mixture of Ni3Al and protective flux based on CaF2 and LiF was used as the initial materials for cladding. X-ray diffraction and EDX data showed that the main phases contained in the coatings were Ti3Al and Ti2Ni-type intermetallic phases. The average microhardness coatings was 600…700 HV, which is ∼ 2 times higher than base material Ti-6Al-4V.

Structure and Properties of Austenitic Steel Surface-doped with NbC

The coatings with NbC were formed on the austenitic (12X18H9T) steel by non-vacuum electron beam cladding. The structure and properties of the obtained materials were investigated. The thickness of the formed coatings ∼1.8 mm, the structure is austenite with distributed niobium carbides. The microhardness of the coatings is ∼400-450 HV, which is 2 times higher than the initial material hardness. It was defined that wear resistance also increases twice as much compared to the steel. The sample obtained with a beam current of 24 mA has the best distribution of strengthening phase and properties.

Surface Hardening of Titanium Under Non-Vacuum Electron-Beam Cladding of an Aluminum-Containing Powder Mixture

Special features of the structure of surface layers formed on billets of commercial-purity titanium VT1-0 by cladding a powder aluminum-titanium mixture with an electron beam removed into air atmosphere are studied. X-ray phase analysis and transmission electron microscopy are used to show that the material remelted by the electron beam is Ti3Al titanium aluminide. The hardness of the deposited layer is 540 – 610 HV. The behavior of the material is studied under the conditions of sliding friction and friction against fixed abrasive particles. The results reflect decrease in the friction factor and increase in the wear resistance of the clad material as compared to commercially pure titanium.

Effect of Electron Beam Power Density on the Structure of Titanium Under Non-Vacuum Electron-Beam Treatment

The structure of surface layers of titanium alloy OT4 subjected to non-vacuum electron-beam treatment with power density of the beam equal to 0.28 – 0.90 kW/cm2 is analyzed. The microstructure of different zones of the material after the treatment and the crystallographic texture appearing in the surface layers as a result of the electron-beam impact are studied. The microhardness of the remelted layers and of the heat-affected zone is measured. Mathematical modeling is used to obtain the distribution of the temperatures and the heating and cooling rates over cross section of the treated material.

Raising the Resistance of Chromium-Nickel Steel to Hydroabrasive Wear by Non-Vacuum Electron-Beam Cladding with Boron

The effect of the structural transformations during non-vacuum electron-beam cladding of amorphous boron powder on the hydroabrasive wear resistance of the surface layers of a chromium-nickel austenitic steel is studied. It is shown that the cladding yields a coating with densely arranged borides. An x-ray method is used to show that the modified layer consists virtually fully of Fe2 B iron borides. This structure raises the hydroabrasive strength of steel 12Kh18N9T by a factor of 1.5 – 2.

Structure and Properties of Functional Self-Fluxing Nickel-Containing Coatings Obtained by Non-Vacuum Electron-Beam Cladding

The microstructure of self-fluxing Ni – Cr – Si – B coatings formed on steel plates with the use of non-vacuum electron-beam cladding is studied. The effect of the structure and phase composition of the coatings on the level of their hardness is determined.

Beam extraction using non vacuum electron beam by reduced acceleration voltage

One of the disadvantages of the non-vacuum electron beam (NVEB) systems is a high acceleration voltage, which leads to an increase of defence against X-ray radiation. Due to the reduced acceleration voltage. On the one hand, the size of the beam generator can be reduced, which leads to a significant weight reduction compared to the conventional EB technology, so that a robotic application comes in focus. On the other hand, the requirements for the X-ray protection are reduced because the penetration ability of the X-radiation decreases. For applications such as brazing, cladding and surface heat-treatment, by the low acceleration voltage non-vacuum electron beam (LAVNVEB) system is of great interest. Some of the first experiments on electron beam emission into the atmosphere with a low acceleration voltage (from 60kV and below) were carried out at an available LAVNVEB system at the Institute of Materials Science at the Leibniz University Hannover.

A new 3D printing method based on non-vacuum electron beam technology

Electron beam freeform fabrication (EBF3) is one the of rapid manufacturing methods, which produces metal parts using an electron beam and wire feed unit in a layer additive fashion without need of mold or jigs. The main disadvantage of EBF3 is that the process is carried out in a chamber, which not only takes a lot of time to evacuate but also limits the size of the part being printed. Non-vacuum electron beam (NVEB) welding is widely used in industry field as a reason for its high production volumes. So a NVEB 3D printing device based on a non-vacuum electron beam welding machine from SST is designed. A serial of experiments is carried out to get a deep understand of 3D printing processing procedure using non-vacuum electron beam system and find a suitable process window. Result shows that droplet transfer mode is one of the most important parameters which determines the quality of the deposition.

The use of non-vacuum electron beam (NVEB) technology as an universal manufacturing process for welding and cutting of high-strength steels

This publication presents the advantages of NVEB technology as an universal tool for material processing based on our investigations on welding and cutting of high-strength S960QL, S1100 and S1300 steels. In this work, the effect of welding cooling time t8/5 on the microstructure of the heat-affected zone (HAZ) and mechanical properties of the joints were investigated. The new process NVEB-cutting with a local suction produces extremely high cutting speeds, up to 17 m/min with high quality edges, render this method a significant development for new NVEB-applications. To demonstrate the capabilities of the non-vacuum electron beam as a universal tool for the technological process chain, the samples of steel S1100QL were made, while cutting and welding was carried out by one machine basement. The experimental results will be shown and discussed.

The Structure, Microhardness and Wear Resistance of Coatings Obtained through Non-Vacuum Electron Beam Cladding of Chromium and Titanium Carbides on Low Carbon Steel

An interrelation between structural features, microhardness and wear resistance was studied in the coatings obtained by non-vacuum relativistic electron beam cladding of chromium and titanium carbides powder mixture on low carbon steel. Five coatings differing in the amount of the entered energy were investigated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), indentation tests and wear resistance measurements. It was found that the concentration of alloying elements both in solid solution and eutectic as well as the volume fraction of eutectic are the main structural characteristics which defines the microhardness of the coatings. The distribution of TiC phase plays a key role in the resistance to wear.

Поверхностное упрочнение сплава ВТ1-0 с использованием технологии вневакуумной электронно-лучевой наплавки порошковых смесей

Поверхностное упрочнение сплава ВТ1-0 с использованием технологии вневакуумной электронно-лучевой наплавки порошковых смесей