OBRABOTKAMETALLOV technology Vol. 27 No. 1 2025 were selected to ensure sufficient rigidity of the samples during milling and to minimize the influence of fixturing on the experimental results. The use of standardized dimensions allows the results to be compared with data from other studies. The specimens were fabricated by WAAM using Inconel 625 wire (the alloy composition is provided in Table). The choice of Inconel 625 is due to its wide application in high-temperature conditions and its complex microstructure, which allows us to investigate the influence of the WAAM process on the mechanical properties and machinability of the material. To ensure the reproducibility of the results, the wire depositing process was carried out using strictly controlled parameters (wire depositing speed, arc voltage, shielding gas flow rate, etc.) optimized to produce the minimum number of defects and the most homogeneous microstructure possible. These parameters will be described in detail in the relevant section of the study. Chemical composition of Inconel 625 nickel alloy wire Chemical element Ta Al Nb Mo Cr Si Fe Co Ti Mn Ni % 0.3 0.38 2.8 7.5 22.5 0.8 1.3 0.2 0.35 0.1 63.68 Fabrication of samples by wire arc additive manufacturing (WAAM) The samples were printed using a wire arc additive manufacturing machine. This equipment was developed and manufactured at Tomsk Polytechnic University. Manufacturing of Inconel specimens by the wire arc additive manufacturing (WAAM) method was carried out according to the following technology. First, a 3D computer model was created using a CAD system. Then this model was divided into separate layers, each of which was to be deposited. The layer-by-layer wire depositing process was carried out on a 3D printer using the specified parameters: current was 115–135 A, voltage 21–24 V, and wire depositing speed was 300 mm/min. An inverter rectifier was used as a power source, which provides high process stability and control of surfacing parameters. Wire depositing was carried out on a moving table, providing precise positioning in X and Y axes, which guarantees accurate reproduction of the geometrical parameters of the model. The Z-axis positioning of the depositing torch was controlled for accurate and homogeneous layers’ depositing. The melting of the wire and the fusion of the substrate (or previous layer) took place using a controlled trajectory of the torch, guaranteeing accurate wire depositing and minimal deviation from the model. The thickness of the wire depositing layer varied from 2 to 5 mm depending on the selected wire depositing modes and the required accuracy. The specified wire depositing modes were optimized to achieve the desired quality and minimum defects, suitable for subsequent stages of the study. For the printing process, the substrate material was the same as the wire: a heat-resistant nickel-based alloy. Printing was carried out in an argon shielding gas environment. Investigation of microstructure and hardness of the obtained samples Chemical etching was carried out to reveal microstructural features of Inconel 625 samples fabricated by wire arc additive manufacturing. The etching process was carried out by immersing the samples in a specially prepared etching solution for 8 minutes. The solution was a mixture of hydrochloric acid (10 ml), hydrofluoric acid (10 ml), and ethanol (100 ml). This particular etchant composition was chosen due to its effectiveness in revealing microstructural details of nickel alloys such as Inconel 625, providing sufficient contrast between the different phases and grain boundaries. After etching, the samples were thoroughly rinsed with distilled water and dried with compressed air to prevent corrosion and ensure high precision of analysis. The samples obtained after etching were examined using a Carl Zeiss AxioMAT optical microscope, which provides high resolution and measurement accuracy. The use of this microscope allowed obtaining detailed images of the microstructure, including analysis of grain size and shape, identification of dendritic structure, determination of the presence of secondary phases and other structural inhomogeneities, which are
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