OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 25 No. 4 2023 increase in hardness of the Ti-2Al-1.5Mn alloy in the surface layers during cutting [18], which was observed in previous work, is at a much lower level and is due to quenching effects (1.5-fold increase compared to the base metal). The size of the fusion zone and the heat affected zone are at a rather low level. In total, the values of macrogeometric distortion, fusion zone and heat affected zone are about 500 µm (0.5 mm) for Grade2 alloy when cutting according to the optimum mode No. 3, which determines the smallest of the required allowances for subsequent machining of this alloy. Conclusion The influence of high-energy plasma jet impact on the structure and properties of A5056, A2024, and Grade2 alloys is expressed in different ways due to its different structure and response to thermal effects. While aluminum alloys are characterized by a decrease in hardness due to thermal degradation of the structure, titanium alloy is characterized by the formation of surface layers with high hardness. The conducted studies show that for the selected alloys, under relatively equal cutting conditions, different cutting parameters and modes are preferable. For alloy A2024, modes with minimum heat input are more preferable, while for alloys A5056 and Grade2, modes with average or above average heat input are more suitable. Aluminum alloys are characterized by softening of the near-surface layers of the material during cutting, while titanium alloys are not. In addition, when cutting Grade2 titanium alloy, oxide layers with hardness significantly (more than 10 times) higher than the hardness of the base metal are formed in the surface layers, which may lead to increased intensity of tool wear during subsequent machining. The A5056 alloy is characterized by a decrease in microhardness up to 10 % in comparison with the base metal during machining. In the heat affected zone of alloy A2024, hardening is significantly higher and is up to 50 % relative to the initial structure of the sheet. Also for these alloys different features of macrogeometry distortion in the cutting zone are observed. A5056 alloy specimens have the most significant deviations, A2024 and Grade2 alloys are characterized by smaller and relatively close values of deviations. Moreover, under the experimental conditions, even with optimal values of cutting parameters, there are still quite significant distortions of the cutting geometry in the A5056 alloy specimens, which requires further research to improve the quality of the cut. In general, the cutting modes used made it possible to produce billets from A5056, A2024 and Grade2 alloys with a thickness of 10 mm and with an allowance for subsequent machining of 1.4; 0.6 and 0.5 mm, respectively. References 1. Murua J., Ibañez I., DianovaA., Domínguez-Meister S., Larrañaga O., LarrañagaA., Braceras I. Tribological and electric contact resistance properties of pulsed plasma duplex treatments on a low alloy steel. Surface and Coatings Technology, 2016, vol. 454, p. 129155. DOI: 10.1016/j.surfcoat.2022.129155. 2. Kolubaev A.V., Sizova O.V., Denisova Yu.A., Leonov A.A., Teryukalova N.V., Novitskaya O.S., Byeli A.V. Structure and properties of CrN/TiN multilayer coatings produced by cathodic arc plasma deposition on copper and beryllium-copper alloy. Physical Mesomechanic, 2022, vol. 25 (4), pp. 306–317. DOI: 10.1134/ S102995992204004X. 3. Wang L., Zhang F., Ma H., He S., Yin F. Microstructure evolution and mechanical properties of plasma sprayed AlCoCrFeNi2.1 eutectic high-entropy alloy coatings. Surface and Coatings Technology, 2023, vol. 471, p. 129924. DOI: 10.1016/j.surfcoat.2023.129924. 4. Akkurt A. The effect of cutting process on surface microstructure and hardness of pure and Al 6061 aluminium alloy. Engineering Science and Technology, an International Journal, 2015, vol. 18 (3), pp. 303–308. DOI: 10.1016/j.jestch.2014.07.004. 5. Ilii S.M., Coteată M. Plasma arc cutting cost. International Journal of Material Forming, 2009, vol. 2 (1), pp. 689–692. DOI: 10.1007/s12289-009-0588-4. 6. Bini R., Colosimo B.M., Kutlu A.E., Monno M. Experimental study of the features of the kerf generated by a 200A high tolerance plasma arc cutting system. Journal of Materials Processing Technology, 2008, vol. 196 (1–3), pp. 345–355. DOI: 10.1016/j.jmatprotec.2007.05.061.
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