OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 25 No. 4 2023 value of the necessary allowance for machining. In the cutting zone of A2024 alloy specimens, the decrease in microhardness is more significant. With the average microhardness in the base metal zone of 1.52–1.53 GPa, the microhardness in the fusion zone decreases to 0.95–1.05 GPa. At the same time, the total size of the heat affected zone and the fusion zone basically does not exceed 500 µm. For the specimens obtained in optimal mode No. 4, the total size of the heat affected zone and the fusion zone, summarized with the value of the macro distortion of the cutting geometry, is 600 µm (0.6 mm). The Grade2 alloy is characterized by a sharp increase in microhardness values on average from 1.23–1.24 GPa in the base metal to 7.0–16.5 GPa in the surface layers, indicating the formation of high-hardness titanium oxides. The a b c d e f Fig. 8. Changes in microhardness of typical specimens after plasma cutting: AA5056 alloy (a, b); AA2024 alloy (c, d); Grade2 titanium alloy (e, f)
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