Abstract
<jats:p>Introduction. Nickel-based alloys such as Inconel 625 are widely used in the aerospace industry due to their high heat resistance and corrosion resistance. However, their machining is complicated by the low thermal conductivity of the material, its tendency to work hardening, and accelerated tool wear. The advent of additive technologies makes it possible to obtain blanks close to the final shape, but the machinability of such materials has not been sufficiently studied, especially taking into account the anisotropy of properties caused by synthesis conditions. In this regard, the study of cutting forces, the explanation of chip morphology, and the description of the causes of tool wear during milling of additively manufactured Inconel 625 is an urgent task. Methods. The samples were obtained by electron beam additive manufacturing (EBAM) from Inconel 625 wire. Milling was carried out with uncoated cemented carbide end mills. The cutting forces were recorded using a three-component dynamometer Kistler mod. 9257BA. The microstructure, chip morphology, and tool wear were studied by scanning electron microscopy using energy-dispersive analysis and X-ray diffraction analysis. Results and discussion. It has been found that in conventional milling, the cutting forces increase linearly with increasing feed rate. The cutting speed of 23.8 m/min reduces cutting forces compared to 11.9 m/min, but leads to an increase in chip length and deterioration of its removal. Machinability anisotropy is revealed: the cutting forces along the synthesis direction exceed the corresponding values when milling transversely across, which correlates with a higher yield strength in the longitudinal direction. The chip length increases with increasing feed rate and cutting speed, reaching 1.55 mm under maximum conditions, while the chips lose their coiled shape and become cracked. The dominant wear mechanism is adhesion-fatigue wear, confirmed by the presence of WC particles on the rake surface of the chips and the formation of Cr23C6 and NiW phases on the cutting edges. Oxidative wear does not play a significant role. X-ray diffraction analysis showed a decrease in the initial crystallographic texture in the chips and on the machined surface, as well as a broadening of the peaks, indicating severe plastic deformation. Conclusions. Rational milling parameters have been determined (cutting speed from 11.9 to 23.8 m/min, feed rate of no more than 200 mm/min, depth of cut up to 1 mm, width of cut up to 7 mm), ensuring tool operability. An increase in the feed rate to 250 mm/min leads to catastrophic failure of the cutting edges. The results obtained can be used to develop technological recommendations for the subtractive machining of parts made of additively manufactured Inconel 625 (EBAM).</jats:p>