OBRABOTKAMETALLOV Vol. 24 No. 4 2022 technology Conclusion The research shows that for the cutting of AA2024 aluminum alloy and Ti-1.5Al-1.0Mn titanium alloy with thickness up to 12 mm it is possible to regulate the cutting speed within a wide range, while for rolled C1220 copper and AA2024 aluminum alloy with thickness of 40 mm the range of regulation of the cutting speed is quite narrow. Intensive heat removal of copper rolled products allows obtaining a cut with minimal values of a partial or complete melting zone, although it is possible to obtain rather large amounts of flowed metal in the cutting zone, consisting of melted metal pushed out of the cutting zone. Studies of the cutting processes of aluminum alloy AA2024 and titanium alloy Ti-1.5Al-1.0Mn revealed the depth of thermal effect of cutting, changing from the top to the bottom of the cut. While for aluminum alloy AA2024 due to excessive precipitation of alloying elements from a solid solution in a zone of thermal influence a decrease in microhardness was noted, for alloy titanium alloy Ti-1.5Al-1.0Mn microhardness growth caused by material hardening was characteristic. The analysis of cut surface morphology, macro- and microstructure of the material in the cutting zone, as well as the study of microhardness changes allowed determining the most optimal combination of cutting mode parameters to obtain the most quality cuts. Changing the parameters of the cutting mode allows obtaining a more homogeneous macrogeometry of the cut surface, a smaller depth of the material remelting zone and the heat-affected zone, and smaller changes in the mechanical properties of the material in the cutting zone. For titanium alloy Ti-1.5Al-1.0Mn almost all used modes of cutting were close to optimum, though some of it provides a slightly better cut quality. (mode No. 2 when cutting specimens with thickness of 5 mm and mode No. 1 when cutting specimens with thickness of 10 mm). For aluminum alloy AA2024 specimens with a thickness of 12 mm the best cutting mode was No. 2, and for the specimens with a thickness of 40 mm – mode No. 8. When cutting C1220 copper specimens with a thickness of 40 mm, the best quality of the cut was achieved with the mode No. 7. The obtained results are summarized in Table 2. Ta b l e 2 Change in cut quality indicators depending on plasma cutting modes Alloy S, mm Mode No. Roughnesses, µm Macrogeometry distortion, mm Depth of the heat-affected zone, mm** Ti-1.5Al-1.0Mn 5 1 75–275 0.5–0.6 0.5–1.8 Ti-1.5Al-1.0Mn 5 2* 65–210 0.5–0.6 0.4–0.9 Ti-1.5Al-1.0Mn 5 3 70–245 0.4–0.6 0.5–1.5 Ti-1.5Al-1.0Mn 10 1* 150–330 0.6–1.9 0.3–0.4 Ti-1.5Al-1.0Mn 10 2 110–450 0.6–2.3 0.3–0.4 Ti-1.5Al-1.0Mn 10 3 110–680 0.7–1.9 0.4–0.6 AA2024 12 1 50–80 1.3–1.5 0.5–0.8 AA2024 12 2* 130–150 0.4–0.5 0.5–0.9 AA2024 12 3 100–260 1.3–1.4 0.3–0.8 AA2024 12 4 50–80 2.0–2.3 0.4–0.9 AA2024 12 5 55–240 3.1–3.2 1.6–3.5 AA2024 40 1 210–510 0.9–1.0 12.6–15.6 AA2024 40 2 205–230 2.5–2.6 12.7–15.7 AA2024 40 3 350–460 2.7–2.9 1.7–15.7 AA2024 40 4 260–300 4.5–5.0 12.3–15.3 AA2024 40 5 200–470 0.6–0.7 12.5–12.75 AA2024 40 6 330–600 0.9–1.1 4.0–15.0 AA2024 40 7 320–550 5.0–5.2 5.0–15.0 AA2024 40 8* 470–570 2.8–3.0 4.5–8.5 AA2024 40 9 470–570 1.3–1.5 12.0–13.0 AA2024 40 10 125–520 1.1–1.3 13–16 C1220 40 1 – – 1.3–1.5
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