OBRABOTKAMETALLOV MATERIAL SCIENCE Том 23 № 3 2021 EQUIPMEN . INSTRUM TS Vol. 7 No. 2 2025 are required [1]. Unlike traditional casting and milling methods, EBAM allows fabricating products from dissimilar materials with minimal material loss and without the need for molds and dies [2]. A bimetallic specimen is manufactured from two materials with different properties, which makes it possible to obtain a product with property characteristics distinct from those of the individual materials used. Bimetals should not have defects at the interface between dissimilar materials. When defects occur, specimens lose the required parameters of mechanical or operational properties. The most common design of the interface in bimetallic specimens is an abrupt transition from one material to another. The most common example of such materials is bimetals with a sharp interface based on the “steel-copper” system, manufactured using laser sintering [3, 4]. However, analysis of the literature has shown that creating a smooth interface between dissimilar materials when using the laser sintering method is difficult. Therefore, EBAM provides unprecedented freedom of microstructural design during manufacturing. One of the fundamental aspects affecting EBAM efficiency is the interaction of the electron beam with the metal wire [5]. The theory of electron scattering plays an important role in determining the depth of beam penetration, the shape and size of the melt pool, as well as in controlling the heat flows that affect material crystallization [6]. Insufficient attention to these factors can lead to reduced mechanical strength, deteriorated geometric accuracy, and an increased number of defects in finished products [7]. Understanding these processes allows predicting microstructure formation, minimizing defects such as porosity, cracks, and structural heterogeneity, as well as optimizing printing parameters to achieve the best results [8]. The process is based on a cathode assembly, which increases energy to overcome the potential barrier due to high temperature and the potential difference between anode and cathode [9]. In addition to the cathode assembly, electron guns operate to form and focus directed electron beams, which are accelerated under the action of an electric field and focused by a magnetic field, forming a directed electron beam [10]. The focused electron beam emitted by the cathode, under the influence of high temperatures, converts the released thermal energy, thereby forming local heating and melting the material. Through the simultaneous operation of the wire feeder and the electron beam along a predetermined trajectory, the material is built up layer by layer, forming a three-dimensional structure after solidification. Depending on the amount of energy emitted by the beam, the intensity of scattering will be greater at a lower energy value. However, at a higher energy value, there is a probability of expanding the heat-affected zone, which leads to excessive penetration of the fed wire onto the substrate or already deposited layers. The scanning size in electron beam 3D printing is directly related to the diameter of the electron beam and its interaction with the material. Increasing electron energy leads to greater penetration depth, but also expands the scattering area, which can reduce the geometric accuracy of the manufactured product [1]. To minimize this effect, it is necessary to optimize beam parameters such as energy, focus, and current density. For example, studies show that using an electron beam with low energy allows achieving higher geometric accuracy of the manufactured product, but limits the thickness of the applied layer [2]. At high electron beam energy and low scanning speed, energy will concentrate in the surface layers, which can lead to local overheating, and vice versa. At optimal parameters, energy is evenly distributed throughout the volume, ensuring stable melting and formation of high-quality macro- and microstructure. Insufficient energy transfer, due to electron scattering, can cause incomplete melting of the material, which contributes to the formation of porosity in the structure of the product. In addition, insufficient energy can prevent the material from reaching the melting temperature, which negatively affects the strength of interlayer bonds and increases surface roughness. Also, uneven cooling associated with non-uniform energy distribution contributes to the formation of local stress zones, which can promote the formation of microcracks. These effects emphasize the importance of controlling electron beam parameters and accounting for scattering processes to minimize defects and improve the quality of printed products [11]. This paper examines the influence of the main EBAM process characteristics (current, feed rate, heat input, printing strategy, and material properties), which are part of the electron scattering theory, on the quality of the obtained products. Special attention is paid to experimental studies that allow optimizing the printing process. The aim of this work is to establish the influence of the main EBAM process characteristics (current, feed rate, heat input, printing strategy, and material properties) on the quality of the obtained
RkJQdWJsaXNoZXIy MTk0ODM1