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The 3^rd International biannual conference "Electron Beam Welding and Related Technologies (EBW2019)" was held at National Research University "Moscow Power Engineering Institute (MPEI)" on November 12-15 2019 in Moscow, Russia. The host university MPEI is one of the leading academic institutions in Europe that conducts research in heat and electricity generation, electrotechnical instrumentation design and power engineering machinery building.

The conference is dedicated to research, innovations and novel engineering solutions in electron beam welding (EBW), metals heat treatment, and electrotechnical engineering. More than 50 reports were presented in various areas of EBW technologies, welding materials science, as well as quality control of welded joints. Reports subjects included the following areas: modeling of EBW processes (thermal fields, heat and mass transfer, electron beam energy, metal ionization, etc.), control of EBW parameters and welding equipment, additive manufacturing, diagnostics of mechanical and service properties of welded joints, electron beam welding equipment.

The target audience of the event was not only academics and students but also industry experts and state officers. The conference was attended by 150 participants from technical universities, research and production companies, factories and power plants. The showcases of the event are highly recognizable among the industrial community not only in Russia but all over the continent. This year the events were attended by delegates from such countries as Belarus, Bulgaria, Germany, China, India, Syria, Mongolia, Pakistan, Slovakia, France, and Israel.

This distinguished volume contains the most significant and novel academic research papers presented at the conference and recommended by the organizing committee. All the manuscripts went through a thorough editorial process and were peer-reviewed by two invited referees.

On behalf of the Organizing Committee, we express our gratitude to the sponsors of the conference for financial and informational support. It was a great honor for the editors to work with all the authors, reviewers and organizers.

With the best regards,

Viktor Dragunov,

The Organizing committee Chairman EBW2019 conference,

Science editor, professor of MPEI

All papers published in this volume of IOP Conference Series: Materials Science and Engineering have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

The paper shows the possibility of forming combined electron-ion beams in a single multi-discharge structure that does not contain incandescent elements. A design of the electrode structure of an electron-ion source is proposed, which consists of two «Penning type» discharge cells connected in series (along the axis). It is shown that the interconnection of separately controlled discharges in the structure increases the degree of gas ionization at reduced pressure, as well as the formation of double electric layers in the plasma, which ensure the formation of combined ion-electron flows in a single structure. This is ensured by creating conditions for the drift of the electron beam through the entire part of the electrode structure, which ensures the formation of the ion current of the source, and helps to increase the degree of ionization of the gas in this region. In addition, the deceleration of the electron beam in the ion acceleration gap ensures the return of electrons, which have lost part of their energy to gas ionization, into the region of the formation of the plasma emitting ions. This contributes to an increase in the density of the ion emission current. Some experimental parameters of the beams formed by the developed structure are presented.

The article presents the results of the studies of the influence of technological parameters of plasma hardening on the geometric dimensions of the hardening track using modern research methods. The visualization of the heating spot on the metal surface according to the methodology made it possible to further evaluate the role of anode and cathode spots on the formation of a common heating spot in the process of plasma hardening of metals. It was established that, depending on the effective thermal power of the plasma arc, there are several modes of combustion of the plasma arc. For example, at an arc current of 20 A, there are several characteristic anode spots on the surface in the form of regular circles, which, with an increase in the arc current, contract to the center of the common heating spot. It has been established that the speed and distance of hardening affects the width of the hardened zone during plasma surface hardening of metals. The region of existence of several regimes of plasma hardening in a common heating spot was revealed, for which both single and group anode spots are characteristic.

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.

The paper presents the results of metallographic and tribological studies of laser hardening zones of steel samples. A full factorial experiment on laser hardening with a change in the distance from the focal plane, radiation power and processing speed was carried out. The regularities of changes in the depth and width of the quenching zones are obtained from the regression equations. With low-frequency transverse scanning of the laser beam up to 100 Hz, the hardening zones with a width of 20 mm and a depth of 1.4-2.0 mm in one pass were obtained. The wear resistance of the hardened zones is 3.68 times higher than the base material.

This paper describes the equipment and methods of the beam diagnostics, namely, the beam current density distribution measuring and the beam position and inclines angle determination. Such a diagnosis is aimed at applying on the electron-beam technological installations, in particular, on the electron-beam welding installations. The paper presents the results of the beam current density distribution measurement, describes the design of the beam position and inclines angle measurement system, and presents the results of preliminary tests of the prototype of this system.

The paper presents a method of large thickness parts welding in a narrow gap with filler wire. A modernized deflection magnet is proposed, which allows deflecting an electron beam directly in the zone of weld pool. The distribution of magnetic induction in a local magnetic field along the axis of electron beam guide was measured and the results obtained were compared to the calculated ones. A photographic recording of electron beam deviation in a local magnetic field created by the presented deflection magnet was carried out. The angle of electron beam deviation about electron beam guide axis is estimated.

The paper presents the results of the research of the formation of thin surface corrosion resistant layers on ductile iron with spheroidal graphite. Surface layers were created by a two-step technological process. In a first step, the surface layer material was applied to the surface of the ductile iron by means of a flame-powder coating in a thickness of 0.8 to 1 mm. The treatment of the layer was carried out in the second step by means of a defocused laser beam or a programmed-deflected electron beam. The influence of the laser beam defocusing and the influence of the energy distribution of the deflected electron beam on the characteristics of the formed thin surface layer was studied. 40 mm thick GGG 40 ductile iron samples were used as the substrate experimental material. The Ni-B-Si-type nickel powder with the designation NP22 and Ni-Cr-B-Si-type nickel powders of the type NP52 were used to form the surface layer. The quality of layers was assessed on the basis of surface forming, metallographic evaluation of selected properties of the layer and measurement of micro-hardness at the interface of the layer and the substrate material.

The results of studies of magnetic and thermoelectric properties of pearlite, martensitic and austenitic steels are given. The magnetization curves for the materials under study, as well as dependences of absolute thermoelectric power on the material temperature are obtained. The data of magnetic induction changing at the control points above the welded samples during EBW are achieved. The simulation of the magnetic field distribution during electron beam welding of dissimilar steels under the conditions of the thermopower currents generation is carried out. The shape of the electron beam being deflected in the magnetic field of thermoelectric currents is calculated. The calculated values are compared to the experimental results.

The results of studies of the structure of an aluminum alloy by the method of backscattered electron diffraction (EBSD) are presented, which allows determining disorientation angles between grains, present data in the form of an array of angles and sizes, direct and inverse pole figures and many other types of useful information, as well as identify boundaries and sub-boundaries grains. It has been shown that friction stir welding is a process with a predominance of shear; the observed shear texture can indicate the local orientation of the material flow during welding. The three-dimensional material flow detected by these texture orientations shows important changes, especially on the advancing side of the weld.

This paper is devoted to the definition of mechanical properties, porosity and chemical composition of the samples made of wrought aluminium alloy AMg6 and obtained by electron beam additive manufacturing with wire feeding. It has been established that ultimate strength of the deposited metal is 90 % of the rolled metal. Chemical composition of the samples has not differed significantly from wire. According to rough estimations porosity has not exceeded 0.055%.

The authors consider the possibilities of using welding in protective gasses with a melting electrode for the manufacture of parts of complex shape. The results of surfacing parts such as square and cylinder are presented. In the course of the research, the technological features associated with the parameters of the welding arc and melting of the surfacing wire were established. Arc current has the greatest effect on the appearance of the molding. The wire feed speed affects the height of the deposited roller. It is shown that the stability of the formation of deposited rollers depends on the transfer modes of the metal, which depend on the conditions of supply and input of wire into the melt pool. The additive technology of metal deposition allows one obtaining parts with a surface different from the base metal, high wear resistance at normal and elevated temperatures, and corrosion resistance. Surfacing can be performed both in the manufacture of new parts and in repair and restoration work, significantly extending the life of parts and assemblies, thereby ensuring a high economic effect.

As there are no cutting forces in High Energy Density (HED) beams like lasers and Electron Beam (EB), their speeds are limited only by their positioning systems. On the other hand, as the entire matrix of the 3D printed part has to be addressed by the thin beam in multiple passes in multiple layers, they have to travel several kilometers in tiny motions. Therefore, the acceleration of the motion system becomes the limiting factor than velocity or precision. The authors have proposed an area-filling strategy for EB to fill the layer with optimal squares to exploit analog and hardware computing. 3D printing requires uniform intensity slanged as flat hat shape whereas the default is Gaussian. The authors have proposed an optimal algorithm that takes into account the maximum velocity and acceleration for achieving a flat hat without any compromise on productivity.

Influence of the gap between the welded edges when sealing the case of electronic devices on the magnitude of the electron emission sensor signal in the process of electron beam welding (EBW) is studied. The impact of electron beam current variation at a constant value of the focusing system current on the penetration depth with the increasing gap between the welded edges is determined. The dependence of the length of the weld at different electron beam currents on samples with an increasing gap between the welded edges is studied. The possibility of controlling the process of electron beam welding by electronic emission from the weld pool is presented. A sensor for electronic emission registration is proposed, which includes an electron collector and an electron current data record system as a part of the EBW installation. The efficiency of the electronic emission sensor directly in the process of sealing under precision welding modes is shown.

The study reveals some formation aspects of a thin walls made by WAAM technology. The series of experiments about thin wall deposition in a various thermal condition was carried out. Temperature field finite element model was developed and solved under the giving conditions. Experimental results were treated after metallographic analysis, functional dependences of the width and height of the deposited layer by the temperature of the previous layer were constructed. In a range of 30-300 C sublayer temperature, layer height and width values show linear functional dependencies by sublayer temperature.

The share of application of laser processing of materials in technological processes of mechanical engineering has increased over the past few years. In this regard, there is a need for reliable control of the technological parameters of the laser welding process. In deep penetration laser welding, part of the beam power is absorbed by the plasma cloud. As a result, a significant decrease in the penetration depth is observed. Using amplitude-time pulse of current in the plasma in the zone of impact of the laser beam on the metal is one of the directions of the work necessary for the control of the processes in the melting channel. The study of the processes of secondary emission in the plasma in the zone of impact of the laser beam on the metal allowed carrying out numerical simulation of the processes during laser welding. The models took into account the dependence on the focusing of the laser beam and other technological parameters of laser welding. The registration of the secondary emission current was also carried out in order to control the geometric parameters of penetration during laser welding. This technique can be used to build methods for the operational control of the welding process.

Low-temperature instrumented indentation tests of welded joints are carried out. The effect of metal cooling on indentation diagrams and metal hardness is investigated. Impact strength tests with a gradual decrease in temperature with the identification of the cold brittleness threshold and determination of the critical brittleness temperature for several structural steels are performed. For an express evaluation of a metal cold resistance, the parameter γ is proposed, which is equal to the ratio of hardness at a given low temperature to hardness at room temperature. The relation between the parameter γ and the temperature coefficient of hardness, which is included in the equation describing low-temperature dependence of hardness, is established. For several grades of carbon and alloy steels, the relation between the parameter γ and the critical brittleness temperature T_0.4, determined by the criterion value of impact strength KCV = 0.4 MJ/m², is established. For welded joints obtained by electron beam welding and arc welding, the values of T_0.4 are determined by the parameter γ in various local zones, including parent metal, heat-affected zone and weld metal. The possibility of establishing the acceptable operation temperature of welded joints using the obtained distributions of the critical brittleness temperature T_0.4 is shown.

The development of new protective coatings is of great fundamental and applied importance for increasing operational properties of surface layers in machine parts, increasing their durability and expanding their functionality. The study is devoted to the creation of coatings based on boron and aluminum on the surface of alloyed steel using a method, combining diffusion saturation (DS) and subsequent electron beam processing (EBP). DS was carried out in saturating pastes based on boron carbide and aluminum at temperature of 1050 °C for 2 hours. As a result of processing, a diffusion layer with thickness of up to (5.6-5.8) × 10² μm and complex structure with depth-heterogeneous composition was formed on the steel surface. The subsequent EBP led to a complete transformation of the primary diffusion layer and an increase in its thickness to 10³ μm. XRD analysis showed significant differences in composition before and after EBP: after EBP tungsten borides (WB, W₂B₉) and iron (Fe₂B) were detected. In addition, it was determined that the distribution of microhardness and elemental composition (B, Al, W) over the depth of the layer after EBP have a more favorable profile without significant fluctuations compared to the sample after DS.

A methodology for shear and tension "ring tear-off" tests of copper, aluminum, zinc and nickel coatings laid through gas-dynamic spraying has been considered. It has been shown that the shear and tension test methodology permits obtaining dependences of strength of the bond between the coatings and the substrate on their laying temperature. The cohesive strength tension tests of the copper, aluminum, and zinc coatings using the "ring tear-off" method have shown the minimal spread of the values (≤ 5%) at the brittle character of the coating failure, which enhances the plausibility of the obtained mechanical properties.

The paper presents data on the effect of molybdenum on the hot-tearing susceptibility of the Ni-Cr-Mo-B system when surfacing with nickel-based alloys. With a boron content of 2.5-3.2%, as well as low carbon and silicon content, the alloying elements, depending on a doping concentration, have different effects on the technological strength of the deposited metal. Molybdenum increases the technological strength of alloys. Alloying the deposited metal with molybdenum in an amount up to 12% in alloys with 2.5% boron concentration at 20% chromium does not lead to the disappearance of cracks. At a molybdenum concentration of more than 12%, the number of cracks in the deposited bead decreases and when the molybdenum concentration is equal to 15%, the cracks disappear, and only increasing the molybdenum content to 20%, in the presence of at least 20% chromium in the alloy, makes it possible to obtain deposited metal without cracks.

The research is devoted to the development of methods for forecasting microstructure of a welded joint in relation to the temperature-time modes of an electron-beam welding (EBW). The analysis of the simulation models and methods existing in the practice of thermal treatment and relating to austenite decomposition kinetics during cooling was carried out to choose methods for forecasting the forming microstructure in a welded joint at EBW. On the basis of these models one method for forecasting the microstructure of welded joints at EBW is offered in this work.

Industrial application of hollow cathode arc (HCA) discharge necessitates understanding the processes of interaction between the plasma and the cathode and the anode, as well as related processes. The first step is to study the formation process of HCA discharge in vacuum with the micro-flow of plasma-forming gas through the hollow cathode. In this work presents a two-dimensional model describing the related processes of transfer of charged particles and the movement of plasma-forming gas flows. Electron density and mean electron energy are calculated by solving the drift-diffusion equations. The mass transfer equation for a multicomponent mixture is used to describe the mass transfer of heavy plasma particles. To calculate the electric field strength the Poisson equation is used. The emission of secondary electrons from the inner surface of the cathode is taken into account. The boundary conditions take into account the loss of charge as a result of chaotic motion and its occurrence due to thermal emission effects. The gas flow is determined by collisions and diffuse re-reflection from all surfaces assumed in accordance with Knudsen's law. Calculations of plasma formation and the movement of plasma-forming gas flows were performed using the simulation package COMSOL Multiphysics.

One of the most actual problems during electron beam welding of metal materials is the determination of the laws of primary electrons interaction with a gas (vapor) flow, taking into account existing and generated (by charged particles) electric fields. The paper is devoted to the development of computer simulation method for the process of electron beam passage through a layer of evaporated metal. The analysis of simulation results showed a significant effect of ionization process on electric field in a gas-vapor channel. It was established that at the initial stage of the process, a region with a positive potential is formed in the lower part of gas-vapor channel, and in its upper part, on the contrary, potential decreases.

The keyhole mode of selective laser melting (SLM) of metal powder bed in additive technology is characterized by an intensive hydrodynamic process in a thin molten layer. Such a mode is widely used also in laser and electron beam welding indicating the similarity of hydrodynamic processes in these technologies despite a significant difference of operating parameters. The threshold conditions of thermocapillary keyhole mode transition for various metals (Cu, Fe, Ti) in a wide range of beam parameters used for selective laser melting of metal powder layer and laser welding are investigated. The condition of threshold for thermocapillary transition into keyhole mode by sticking of viscous layer to the solid boundary is formulated. The fulfillment of this condition is confirmed by the convergence of estimated values of the viscous layer thickness and the molten layer depth during the transition to a keyhole mode. Analytical estimates of keyhole threshold and comparisons with experimental values of beam power and spot size corresponding to the transition in keyhole mode for SLM processes and laser welding are presented. The correlation of these values confirms the thermocapillary mechanism of cavity formation and the similarity of hydrodynamic processes in laser welding and SLM processing in keyhole mode at wide range of operating parameters.

The paper presents the results of a heat treatment impact on the weld metal hardness of EP517 steel to 36NKhTYu alloy dissimilar welded joints. Aging curves for the weld metal in the temperature range from 600°C to 750°C and with an aging time of up to 64 hours are performed. Metallographic researches of weld metal and heat-affected zone (HAZ) are carried out. It was established that the greatest increase of hardness is reached after the exposure for 32 hours at 650°C and after the exposure for 16 hours at 700°C. It was found that after the aging with the specified conditions, weld metal hardness increases by 36% (60 HV) in comparison with its hardness after welding. The microstructure research showed that the decomposition fraction of supersaturated solution in HAZ of 36NKhTYu alloy significantly depends on the temperature and reaches its ultimate value after the aging at a temperature of 700°C.