Vol. 26 No. 4 2024 3 EDITORIAL COUNCIL EDITORIAL BOARD EDITOR-IN-CHIEF: Anatoliy A. Bataev, D.Sc. (Engineering), Professor, Rector, Novosibirsk State Technical University, Novosibirsk, Russian Federation DEPUTIES EDITOR-IN-CHIEF: Vladimir V. Ivancivsky, D.Sc. (Engineering), Associate Professor, Department of Industrial Machinery Design, Novosibirsk State Technical University, Novosibirsk, Russian Federation Vadim Y. Skeeba, Ph.D. (Engineering), Associate Professor, Department of Industrial Machinery Design, Novosibirsk State Technical University, Novosibirsk, Russian Federation Editor of the English translation: Elena A. Lozhkina, Ph.D. (Engineering), Department of Material Science in Mechanical Engineering, Novosibirsk State Technical University, Novosibirsk, Russian Federation The journal is issued since 1999 Publication frequency – 4 numbers a year Data on the journal are published in «Ulrich's Periodical Directory» Journal “Obrabotka Metallov” (“Metal Working and Material Science”) has been Indexed in Clarivate Analytics Services. Novosibirsk State Technical University, Prospekt K. Marksa, 20, Novosibirsk, 630073, Russia Tel.: +7 (383) 346-17-75 http://journals.nstu.ru/obrabotka_metallov E-mail: metal_working@mail.ru; metal_working@corp.nstu.ru Journal “Obrabotka Metallov – Metal Working and Material Science” is indexed in the world's largest abstracting bibliographic and scientometric databases Web of Science and Scopus. Journal “Obrabotka Metallov” (“Metal Working & Material Science”) has entered into an electronic licensing relationship with EBSCO Publishing, the world's leading aggregator of full text journals, magazines and eBooks. The full text of JOURNAL can be found in the EBSCOhost™ databases.
OBRABOTKAMETALLOV Vol. 26 No. 4 2024 4 EDITORIAL COUNCIL EDITORIAL COUNCIL CHAIRMAN: Nikolai V. Pustovoy, D.Sc. (Engineering), Professor, President, Novosibirsk State Technical University, Novosibirsk, Russian Federation MEMBERS: The Federative Republic of Brazil: Alberto Moreira Jorge Junior, Dr.-Ing., Full Professor; Federal University of São Carlos, São Carlos The Federal Republic of Germany: Moniko Greif, Dr.-Ing., Professor, Hochschule RheinMain University of Applied Sciences, Russelsheim Florian Nürnberger, Dr.-Ing., Chief Engineer and Head of the Department “Technology of Materials”, Leibniz Universität Hannover, Garbsen; Thomas Hassel, Dr.-Ing., Head of Underwater Technology Center Hanover, Leibniz Universität Hannover, Garbsen The Spain: Andrey L. Chuvilin, Ph.D. (Physics and Mathematics), Ikerbasque Research Professor, Head of Electron Microscopy Laboratory “CIC nanoGUNE”, San Sebastian The Republic of Belarus: Fyodor I. Panteleenko, D.Sc. (Engineering), Professor, First Vice-Rector, Corresponding Member of National Academy of Sciences of Belarus, Belarusian National Technical University, Minsk The Ukraine: Sergiy V. Kovalevskyy, D.Sc. (Engineering), Professor, Vice Rector for Research and Academic Aff airs, Donbass State Engineering Academy, Kramatorsk The Russian Federation: Vladimir G. Atapin, D.Sc. (Engineering), Professor, Novosibirsk State Technical University, Novosibirsk; Victor P. Balkov, Deputy general director, Research and Development Tooling Institute “VNIIINSTRUMENT”, Moscow; Vladimir A. Bataev, D.Sc. (Engineering), Professor, Novosibirsk State Technical University, Novosibirsk; Vladimir G. Burov, D.Sc. (Engineering), Professor, Novosibirsk State Technical University, Novosibirsk; Aleksandr N. Korotkov, D.Sc. (Engineering), Professor, Kuzbass State Technical University, Kemerovo; Dmitry V. Lobanov, D.Sc. (Engineering), Associate Professor, I.N. Ulianov Chuvash State University, Cheboksary; Aleksey V. Makarov, D.Sc. (Engineering), Corresponding Member of RAS, Head of division, Head of laboratory (Laboratory of Mechanical Properties) M.N. Miheev Institute of Metal Physics, Russian Academy of Sciences (Ural Branch), Yekaterinburg; Aleksandr G. Ovcharenko, D.Sc. (Engineering), Professor, Biysk Technological Institute, Biysk; Yuriy N. Saraev, D.Sc. (Engineering), Professor, V.P. Larionov Institute of the Physical-Technical Problems of the North of the Siberian Branch of the RAS, Yakutsk; Alexander S. Yanyushkin, D.Sc. (Engineering), Professor, I.N. Ulianov Chuvash State University, Cheboksary
Vol. 26 No. 4 2024 5 CONTENTS OBRABOTKAMETALLOV TECHNOLOGY Manikanta J.E., Ambhore N., Shamkuwar S., Gurajala N.K., Dakarapu S.R. Investigation of vegetable-based hybrid nanofl uids on machining performance in MQL turning........................................................................................... 6 Dama Y.B., Jogi B.F., Pawade R., Kulkarni A.P. Impact of print orientation on wear behavior in FDM printed PLA Biomaterial: Study for hip-joint implant...................................................................................................................... 19 GrinenkoA.V., ChumaevskyA.V., Sidorov E.A., Utyaganova V.R.,AmirovA.I., Kolubaev E.A. Geometry distortion, edge oxidation, structural changes and cut surface morphology of 100mm thick sheet product made of aluminum, copper and titanium alloys during reverse polarity plasma cutting...................................................................................... 41 Somatkar A., Dwivedi R., Chinchanikar S. Comparative evaluation of roller burnishing of Al6061-T6 alloy under dry and nanofl uid minimum quantity lubrication conditions............................................................................................... 57 Karlina Yu.I., Konyukhov V.Yu., Oparina T.A. Assessment of the quality and mechanical properties of metal layers from low-carbon steel obtained by the WAAM method with the use of additional using additional mechanical and ultrasonic processing..................................................................................................................................................... 75 EQUIPMENT. INSTRUMENTS Yusubov N.D., Abbasova H.M. Systematics of multi-tool setup on lathe group machines............................................... 92 Toshov J.B., Fozilov D.M., Yelemessov K.K., Ruziev U.N., Abdullayev D.N., Baskanbayeva D.D., Bekirova L.R. Increasing the durability of drill bit teeth by changing its manufacturing technology......................................................... 112 Pospelov I.D. Investigation of the distribution of normal contact stresses in deformation zone during hot rolling of strips made of structural low-alloy steels to increase the resistance of working rolls..................................................... 125 Ablyaz T.R., Blokhin V.B., Shlykov E.S., Muratov K.R., Osinnikov I.V. Manufacturing of tool electrodes with optimized confi guration for copy-piercing electrical discharge machining by rapid prototyping method.......................... 138 MATERIAL SCIENCE Shubert A.V., Konovalov S.V., Panchenko I.A. A review of research on high-entropy alloys, its properties, methods of creation and application.................................................................................................................................................. 153 Syusyuka E.N., Amineva E.H., Kabirov Yu.V., Prutsakova N.V. Analysis of changes in the microstructure of compression rings of an auxiliary marine engine.......................................................................................................... 180 Dudareva A.A., Bushueva E.G., Tyurin A.G., Domarov E.V., Nasennik I.E., Shikalov V.S., Skorokhod K.A., Legkodymov A.A. The eff ect of hot plastic deformation on the structure and properties of surface-modifi ed layers after non-vacuum electron beam surfacing of a powder mixture of composition 10Cr-30B on steel 0.12 C-18 Cr-9 Ni-Ti............................................................................................................................................................................. 192 Boltrushevich A.E., Martyushev N.V., Kozlov V.N., Kuznetsova Yu.S. Structure of Inconel 625 alloy blanks obtained by electric arc surfacing and electron beam surfacing........................................................................................... 206 Sablina T.Y., Panchenko M.Yu., Zyatikov I.A., Puchikin A.V., Konovalov I.N., Panchenko Yu.N. Study of surface hydrophilicity of metallic materials modifi ed by ultraviolet laser radiation........................................................................ 218 EDITORIALMATERIALS 234 FOUNDERS MATERIALS 243 CONTENTS
OBRABOTKAMETALLOV Vol. 26 No. 4 2024 TECHNOLOGY Geometry distortion, edge oxidation, structural changes and cut surface morphology of 100mm thick sheet product made of aluminum, copper and titanium alloys during reverse polarity plasma cutting Artem Grinenko 1, a, Andrey Chumaevsky 2, b, *, Evgeny Sidorov 2, c, Veronika Utyaganova 2, d, Alihan Amirov 2, e, Evgeniy Kolubaev 2, f 1 ITS-Siberia LLC, Krasnoyarsk, 16a Severnoe shosse, 660118, Russian Federation 2 Institute of Strength Physics and Materials Sciences SB RAS, 2/4, pr. Akademicheskii, Tomsk, 634055, Russian Federation a https://orcid.org/0009-0002-9511-1303, giga2011@yandex.ru; b https://orcid.org/0000-0002-1983-4385, tch7av@gmail.com; c https://orcid.org/0009-0009-2665-7514, eas@ispms.ru; d https://orcid.org/0000-0002-2303-8015, veronika_ru@ispms.ru; e https://orcid.org/0000-0002-5143-8235, amir@ispms.tsc.ru; f https://orcid.org/0000-0001-7288-3656, eak@ispms.tsc.ru Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2024 vol. 26 no. 4 pp. 41–56 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2024-26.4-41-56 ART I CLE I NFO Article history: Received: 17 September 2024 Revised: 01 October 2024 Accepted: 10 October 2024 Available online: 15 December 2024 Keywords: Plasma cutting Macrostructure Heat-aff ected zone Metal melting Cutting parameters Reverse polarity current Thick sheet metal Funding The results were obtained in the framework of the Integrated Project “Establishment of production of high-tech equipment for adaptive high-precision plasma heavy cutting of nonferrous metals for the metallurgical, aerospace and transport industries of the Russian Federation” (Agreement No. 075-11-2022012 dated April 06, 2022) implemented by the ISPMS SB RAS at the fi nancial support of the Ministry of Education and Science of the Russian Federation as part of Decree of the Government of the Russian Federation No. 218 dated April 09, 2010. Acknowledgements Research was partially conducted at core facility “Structure, mechanical and physical properties of materials” and center “Nanotech” ISPMS RAS. ABSTRACT The introduction describes the feasibility of using reverse polarity plasma cutting to produce large-sized non-ferrous metal blanks up to 100 mm thick. Data on the use of plasma cutting with direct and reverse polarity currents for thick sheet metal and the main technological problems associated with its implementation are presented. The purpose of the work is to study the organization of the structure and properties of the near-surface zone, changes in the chemical and phase composition when cutting aluminum, copper and titanium alloys. The research methods are optical and scanning electron microscopy, microhardness measurement, X-ray diff raction and energy-dispersive analysis. Plasma cutting was carried out using air as a plasma-forming and shielding gas, simultaneously with water injection into the discharge chamber and the formation of a “water fog” around the plasma column. Results and discussion. It is shown that both the arc stability and the shape of the plasma column are of great importance in reverse polarity plasma cutting of rolled sheets. The distortion of the cutting geometry during normal operation is greatest in the central part, and with insuffi cient heat input it shifts to the lower part and increases signifi cantly. The operation of the plasma torch in air does not lead to signifi cant changes in the composition of the cutting surface of aluminum and copper alloys. A decrease in the magnesium content near the edge is typical for the aluminum alloy in the surface layers. Cutting of the titanium alloy is accompanied by intense oxidation of the surface, especially in areas of diffi cult metal displacement from the cutting cavity. The formation of titanium oxides, mainly rutile Ti2O, sharply increases the microhardness values in the surface layers, which negatively aff ects the machinability of the cutting edge and requires shot blasting to remove the oxide layer. The conclusion describes the main patterns of implementing reverse polarity plasma cutting of sheet metal from aluminum, copper and titanium alloys with a thickness of 100 mm. For citation: Grinenko A.V., Chumaevsky A.V., Sidorov E.A., Utyaganova V.R., Amirov A.I., Kolubaev E.A. Geometry distortion, edge oxidation, structural changes and cut surface morphology of 100mm thick sheet product made of aluminum, copper and titanium alloys during reverse polarity plasma cutting. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2024, vol. 26, no. 4, pp. 41–56. DOI:10.17212/1994-6309-2024-26.4-41-56. (In Russian). ______ * Corresponding author Chumaevsky Andrey V., D.Sc. (Engineering), Leading researcher, Institute of Strength Physics and Materials Sciences SB RAS, 2/4, pr. Akademicheskii, 634055, Tomsk, Russian Federation Tеl.: +7 (382) 228-68-63, e–mail: tch7av@ispms.ru
OBRABOTKAMETALLOV TECHNOLOGY Vol. 26 No. 4 2024 Introduction Currently, one of the pressing challenges in domestic industry is the need for high-effi ciency production of non-ferrous metal and alloy blanks for the fabrication of large-scale components and structures. Flame cutting and waterjet cutting methods are capable of cutting thick sheet metal but suff er from low performance [1-3]. Laser cutting off ers high performance but is not suitable for producing thick-section blanks [4, 5]. Conventional mechanical cutting methods do not have the necessary fl exibility for manufacturing complexshaped parts. Plasma cutting combines high performancewith the ability to process thick sheet metal [6-8]. Thismethod is well-suited for both steels and ferrous metals [9, 10], as well as copper, aluminum, and titanium alloys [11-16]. Plasma cutting can produce blanks from thick sheet metal, including materials with thicknesses of 100 mm or more. However, cutting such thick blanks using plasma torches operating on direct polarity current presents signifi cant challenges and leads to considerable wear of the working elements [17, 18]. Moreover, most of the available plasma torches of this type are produced by foreign manufacturers and are not domestically manufactured. Therefore, there is a need to develop alternative plasma cutting equipment of domestic origin. For this purpose, a joint project between the Institute of Strength Physics and Materials Sciences (ISPMS SB RAS) and LLC ITS-Siberia is currently focused on developing equipment for reverse polarity plasma cutting of thick sheet non-ferrous metals and alloys [13-16, 18, 19]. Reverse polarity plasma cutting off ers several advantages over direct polarity. First of all, the consumption of nozzles and electrodes included in the plasma torches is reduced [17, 18]. The second, but no less important factor, is the increase in the thickness of sheet metal that can be cut [15]. Reverse polarity plasma cutting also delivers higher performance at the same power level compared to direct polarity [18, 20-23]. Additionally, it improves the quality of the cut surface and reduces the extent of structural changes caused by thermal eff ects [18]. However, reverse polarity plasma cutting is more complex in terms of optimizing cutting parameters [13-16] and involves specifi c challenges related to the degradation and wear of plasma torch components [18]. Despite the fairly long history of using plasma cutting, there is almost no information in the modern literature regarding the eff ects of the cutting process on the structure and surface quality of sheet metal with a thickness of 100 mm or more when using reverse polarity plasma torches. The aim of this study is to investigate the structural organization, edge distortion, and changes in chemical and phase composition during reverse polarity plasma cutting of aluminum, copper, and titanium alloys. Materials and methods Experimental studies were carried out at the production site of LLC ITS-Siberia and on experimental equipment at the Institute of Strength Physics and Materials Sciences (ISPMS SB RAS). The cutting process was performed using a reverse polarity plasma torch developed as part of a joint scientifi c and technical project. The materials used were 100 mm thick plates of Al-6Mg aluminum alloy, Cu-9Al-2Mn bronze, and Ti-5Al-5Mo-5V titanium alloy in its as-received condition. The schematic of the plasma torch operation and the plasma cutting process is shown in Fig. 1, a. The cutting of 100 mm thick plates (1) was performed using a plasma jet (2) formed in a protective gas environment (3), initiated by the pilot arc (4) at the start of the process and maintained by the main arc (5) during the cutting operation. The supply of the protective and plasma-forming gas (6) to the cutting zone was maintained at a fi xed pressure in the system. The nozzle (7) was secured with a nut (8). Inside the nozzle, a dense vortex stream of gas and plasma (9) was formed, driven by the swirl generator (10) and arc combustion. Additionally, in the developed plasma torch design, water injection (11) into the discharge chamber was implemented through an opening in the working electrode (14). This setup was necessary to improve cut quality and reduce nozzle and electrode wear [16, 18, 19]. To prevent overheating of the nozzle and electrode, a constant fl ow of water (12) was maintained through channels in the torch body (13). Due
OBRABOTKAMETALLOV Vol. 26 No. 4 2024 TECHNOLOGY Fig. 1. Scheme of the reverse polarity plasma torch operation (a); the appearance of the plasma jet at start (b) and in the operating mode (c); an increase in the density of the “water mist” around the plasma jet (d); and the appearance of the cutting zone (d): 1 – plate; 2 – plasma jet; 3 – gas fl ow; 4 – starting arc; 5 – working arc; 6 – fl ow of plasma-forming and protective gas; 7 – nozzle; 8 – external nut; 9 – vortex fl ows of gas and plasma; 10 – swirler; 11 – water supply to the hollow electrode; 12 – supply of cooling water to the plasma torch body; 13 – water cooling channels; 14 – electrode; 15 – solenoid; 16 – inner casing made of PTFE; 17 – outer steel casing; 18 – “water mist” b c d e to the design features of the plasma torch, the water fl ow (13) fi rst passed through the nozzle and electrode, and then partially exited the torch body and partially entered the discharge chamber. Current was supplied to the electrode via a copper solenoid (15), which also generated a magnetic fi eld to focus the plasma jet and electric arc. The inner torch body (16), with water and air supply channels, was made of fl uoroplastic, while the outer body (17) was made of steel. The working electrode (14) and nozzle (7) were made of M1-grade copper (Cu-ETP). At the start of the process, the distance between the plasma torch and the plate was increased (Fig. 1, b), and after arc stabilization, it was reduced (Fig. 1, c). During cutting, the “water mist” around the plasma jet varied signifi cantly due to pressure pulsations in the discharge chamber (Fig. 1, c, d). A large amount of
OBRABOTKAMETALLOV TECHNOLOGY Vol. 26 No. 4 2024 metal combustion products accumulated around the cutting zone, which were displaced by the protective gas fl ow (Fig. 1, e). The arc current during cutting ranged from 350 to 370 A, with a voltage ranged from 370 to 400 V. The height of the plasma torch above the plate surface during cutting was from 16 to 25mm. Gas pressure ranged from2.0 to 4.0 bar, andwater pressure in the systembefore entering the plasma torch cooling circuit was 6 bar. The gap between the nozzle and electrode was between 0.5 and 2.0 mm. The cutting speed varied from 250 to 3,000 mm/min. Air was used as both the plasma-forming and protective gas. After obtaining the experimental samples, metallographic sections for structural analysis were cut from it using electrical discharge machining (DK7750 machine). Structural and morphological studies of the cut surface were conducted using an optical microscope Altami MET 1C, Olympus LEXT 4100 laser scanning microscope, and Zeiss LEO EVO 50 scanning electron microscope equipped with a system for micro-X-ray spectral analysis. The distortion of the cut geometry was determined by the maximum deviation of the cut surface from perpendicularity, using macrostructural images obtained through optical microscopy. The most pronounced edge distortion for the aluminum and copper alloys occurred in the central region (II in Fig. 2, b, c), whereas for the titanium alloy, the greatest distortion was observed at the lower edge (III in Fig. 2, d). The roughest surface texture for all alloy samples was seen at the bottom of the plate (III), while the most uniform cut surface was in the upper region (I). In the subsurface structure of all three alloy types, there were regions of molten metal, a heat-aff ected zone (HAZ), and the base metal with an unchanged structure. The structure of the Cu-9Al-2Mn bronze was the least aff ected by thermal exposure, while the Ti-5Al-5Mo-5V alloy exhibited the largest HAZ, and the Al-6Mg alloy had the thickest molten metal zone. As will be discussed later, these diff erences are due to the thermal conditions, alloy composition, melting temperatures, and thermal conductivity. Results and discussion During plasma cutting of 100 mm thick plates, a specifi c structure formed near the cut surface, along with a characteristic macroscopic relief typical of plasma cutting (Fig. 2). The cut surfaces of the aluminum alloy and bronze exhibited numerous fl ow marks from the metal along the cut edge during the cutting process (Fig. 2, a, c). The cut surface of the titanium alloy, however, showed fewer signs of metal fl ow and was characterized by the presence of microcracks (Fig. 2, e). The most pronounced edge distortion for the aluminum and copper alloys occurred in the central region (II in Fig. 2, b, d), whereas for the titanium alloy, the greatest distortion was observed at the lower edge (III in Fig. 2, e). The roughest surface texture for all alloy samples was seen at the bottom of the plate (III), while the most uniform cut surface was in the upper region (I). In the subsurface structure of all three alloy types, there were regions of molten metal, a heat-aff ected zone (HAZ), and the base metal with an unchanged structure. The structure of the Cu-9Al-2Mn bronze was the least aff ected by thermal exposure, while the Ti-5Al-5Mo-5V alloy exhibited the largest HAZ, and the Al-6Mg alloy had the thickest molten metal zone. As will be discussed later, these diff erences are due to the thermal conditions, alloy composition, melting temperatures, and thermal conductivity. The surface of the Al-6 Mg aluminum alloy after cutting exhibits diff erent structures in the upper, central, and lower parts of the cut (Fig. 3, a–c). The upper part is more uniform, while the lower part contains a higher number of pores and oxidation marks. Microstructural analysis revealed the formation of microcracks (1 in Fig. 3, d) and small spherical pores (2 in Fig. 3, d). Energy-dispersive spectroscopy (EDS) indicated a signifi cant amount of oxygen in the surface layers. The surface layer structure (Fig. 4, a–e) shows distinct regions: the fusion zone (FZ), the heat-aff ected zone (HAZ), and the base metal (BM). The depth of the heat-aff ected zone (HAZ) and base metal (BM) does not exceed 1 mm in the central part. The fusion zone (FZ) contains a large number of coarse secondary phase particles (1 in Fig. 4, d), pores (2 in Fig. 4, f, g), and discontinuities (3 in Fig. 4, g). According to energy-dispersive spectroscopy (EDS) analysis, the fusion zone contains only a small amount of oxygen, but there is a signifi cant change in magnesium content, as shown in Fig. 5, b. The depletion of magnesium in Al-6 Mg -type alloys is expected
OBRABOTKAMETALLOV Vol. 26 No. 4 2024 TECHNOLOGY 10 mm 10 mm 10 mm 10 mm 10 mm 10 mm a b c d e f Fig. 2. The cut surface (a, c, e) and the macrostructure in the cross section (b, d, f) of specimens of aluminum alloy Al-6 Mg (a, b), bronze Cu-9 Al-2 Mn (c, d) and titanium alloy Ti-5 Al-5 Mo-5 V (e, f) after reverse polarity plasma cutting a b c Fig. 3. Images of the cut surface of aluminum alloy Al-6 Mg obtained by laser scanning (a–c) and scanning electron (d–е) microscopy d e f
OBRABOTKAMETALLOV TECHNOLOGY Vol. 26 No. 4 2024 BM HAZ FZ a BM BM HAZ FZ FZ b c d BM HAZ FZ FZ FZ Fig. 4. Macrostructure (a), images of the microstructure obtained by optical (b–d) and scanning electron (e–g) microscopy of a specimen of aluminum alloy Al-6 Mg e f g and is also observed during welding by various methods. X-ray diff raction (XRD) analysis indicated that no phase composition changes occur in the surface layers, and the structure remains Al(Mg) (Fig. 5, c, d). Due to the removal of work hardening and the depletion of magnesium in the surface layers of the aluminum alloy, there is a signifi cant reduction in microhardness, especially in the lower part of the cut (Fig. 5, a). In the upper part of the cut, microhardness decreases from 1.21 GPa in the base metal to 1.01 GPa in the subsurface zone, whereas in the lower part, it reaches approximately 0.94 GPa near the surface. In both the upper and central regions of the cut, at a depth of 1.0 mm, the microhardness returns to values typical of the base metal, but in the lower part, it remains at 1.05 GPa. This indicates a signifi cantly greater thermal impact on the material in the lower section of the cut, due to the displacement of molten metal through this area and the diffi culty in removing it with the protective gas stream. Overall, considering the dimensional tolerances for producing blanks from plates of this thickness, both the cut distortion and the structural changes can be considered acceptable. The surface of the Cu-9 Al-2 Mn bronze after cutting also exhibits signifi cant variations in relief across the upper, lower, and central parts of the cut zone (Fig. 6, a-c). Distinct features are identifi ed, formed by the rapid solidifi cation of metal fl owing down the edge during cutting (1 in Fig. 6, d). Additionally, scanning electron microscopy (SEM) and X-ray diff raction (XRD) analysis reveal fragments of oxides (2 in Fig. 6, e) and formations resembling pores or “craters” (3 in Fig. 6, f). The oxidation of the surface is patchy, and a continuous oxidized layer does not form.
OBRABOTKAMETALLOV Vol. 26 No. 4 2024 TECHNOLOGY a b Fig. 5. Microhardness (a), change in magnesium content (b) in the surface layers of aluminum alloy Al-6 Mg and the results of X-ray analysis of the base metal (c) and the cut surface (d) c d Fig. 6. Images of the cut surface bronze Cu-9 Al-2 Mn obtained by laser scanning (a–c) and scanning electron (d–f) microscopy a b c d e f
OBRABOTKAMETALLOV TECHNOLOGY Vol. 26 No. 4 2024 The structure of the surface layer also includes a melting zone, a heat-aff ected zone, and the base metal (Fig. 7, a-d). Within the materials of these zones, there are pores (1 in Fig. 7, e) and discontinuities (2 in Fig. 7, g). However, the molten metal zone is signifi cantly smaller, with a thickness not exceeding 100-200 μm in the central part, while the heat-aff ected zone is only weakly defi ned (Fig. 7, a-d, Fig. 8, a). The microhardness values in the surface layers show minimal variation, which can be attributed to the high thermal conductivity of the material and rapid cooling. Consequently, energy dispersive spectroscopy (EDS) analysis indicates that no qualitative changes in the phase composition occur within the material (Fig. 8, b, c). The primary phase consists of a solid solution of Cu(Al) and the β’-phase (needle-like Cu3Al present between the grains of the solid solution). In the melting and heat-aff ected zones, only changes in the volume fraction and concentration of these phases can be identifi ed (Fig. 7, c, f). Additionally, secondary phases appear as particles of Cu3Al throughout the material. The high thermal conductivity of the material leads to lesser structural changes in the near-surface zone compared to the aluminum alloy, while also resulting in a larger proportion of material not displaced from the cutting zone in the lower part of the cut, as illustrated in Fig. 2, c. Overall, based on the analysis of geometric distortion and structural changes in the material for plates of this size, the quality of the cut can be considered acceptable. The morphology of the cut surface of the Ti-5Al-5Mo-5V titanium alloy in the upper, lower, and central regions is fairly consistent (Fig. 9, a-c). Unlike copper and aluminum alloys, the surface topography in this case exhibits only minimal traces of the material following the contour of the tool. However, there are HAZ FZ BM BM BM HAZ FZ FZ HAZ FZ FZ HAZ BM FZ а b c d e f g Fig. 7. Macrostructure (a), images of the microstructure obtained by optical (b–d) and scanning electron (e–g) microscopy of a specimen of bronze Cu-9 Al-2 Mn
OBRABOTKAMETALLOV Vol. 26 No. 4 2024 TECHNOLOGY а b c Fig. 8. Change in microhardness in the surface layers of bronze Cu-9 Al-2 Mn (a) and the results of X-ray analysis of the base metal (b) and the cut surface (c) similarly shaped protrusions in the central part of the cut (marked as 1 in Fig. 9, d). The primary reason for the distinctive morphology of the titanium alloy cut surface is the oxidation of the surfaces, which results in the formation of a continuous oxide layer, as confi rmed by SEM and EDS analysis (Fig. 9, e, f). According to EDS and X-ray diff raction (XRD) analysis, the main oxide phase is Ti₂O (Fig. 11, d). The surface layer may also contain dendritic structures that formed during the crystallization of the oxide (marked as 2 in Fig. 9, e), as well as microcracks (marked as 3 in Fig. 9, f), the formation of which occurred during the cooling of the material after cutting. Structural and chemical analysis of the material shows that the melt zone is stable and that oxidation extends across nearly the entire surface (Fig. 10, a; Fig. 11, b), penetrating up to 0.5 mm into the lower part of the cut. The material in the cross-section is also characterized by the presence of a melt zone, a heat-aff ected zone (HAZ), and the base metal (Fig. 10, a-d). During the melting of titanium and its oxides, dendritic structures form. Both the base metal and the heat-aff ected zone exhibit alpha and beta-phase lamellae, as a b c d e f Fig. 9. Images of the cut surface of titanium alloy Ti-5 Al-5 Mo-5 V obtained by laser scanning (a–c) and scanning electron (d–f) microscopy
OBRABOTKAMETALLOV TECHNOLOGY Vol. 26 No. 4 2024 confi rmed by optical microscopy (Fig. 10, b, c) and XRD analysis (Fig. 11, c, d). The melt zone contains relatively large cracks throughout its length (marked as 1 in Fig. 10, e). Near the surface within the fusion zone, the presence of protrusions (marked as 2 in Fig. 10, f) and discontinuities (marked as 3 in Fig. 10, g) can be identifi ed. Due to oxidation in the subsurface layers, there is a noticeable increase in microhardness (Fig. 11, a). The most signifi cant increase in microhardness, reaching up to 8 GPa, occurs in the lower part of the cut zone, with the depth of this zone exceeding 1 mm in this case. In contrast, in the upper part of the cut, both the thermal impact on the material and the degree of edge oxidation are signifi cantly lower, with the depth of these aff ected zones not exceeding 0.3 mm. The oxidation of the titanium alloy in the surface layers is more pronounced compared to that of aluminum alloys, which is attributed to the higher reactivity of titanium and its melting temperature. In the lower part of the cut zone, at the set power of the plasma-generating arc, the complete penetration of the plasma jet through the plate was hindered, resulting in prolonged thermal exposure to the material. It can be determined that in this case, the cut was formed at the limit of the process capability, on the verge of full penetration of the plate and the occurrence of a defect in the form of incomplete cutting. This resulted in more signifi cant oxidation of the edge in the lower part and a deterioration in the overall cut quality. For machining titanium alloy workpieces, this is generally unacceptable, and post-cutting shot blasting is required to remove the scale after plasma cutting. The use of nitrogen as a shielding and plasmagenerating gas is also possible, but for plates of this thickness, slow cooling of the edge is characteristic, HAZ FZ BM BM BM FZ HAZ BM FZ FZ FZ a b c d e f g Fig. 10. Macrostructure (a), images of the microstructure obtained by optical (b–г) and scanning electron (e–g) microscopy of a specimen of titanium alloy Ti-5 Al-5 Mo-5 V
OBRABOTKAMETALLOV Vol. 26 No. 4 2024 TECHNOLOGY particularly for titanium alloys with relatively low thermal conductivity. This makes it diffi cult to avoid edge oxidation due to insuffi cient metal removal from the kerf and excessive melting of the surface. However, increasing the power of the plasma arc source and cutting at a slightly higher current (around 400 A) could allow for acceptable quality cuts on titanium alloy plates up to 100 mm thick, even when using air as the plasma-generating gas. Conclusion The conducted studies demonstrate that it is possible to obtain 100 mm thick blanks from sheet rolled aluminum, copper and titanium alloys using the reverse polarity plasma cutting. The best surface quality of the cut is observed in the Al-6Mg aluminum alloy and Cu-9 Al-2 Mn bronze. These alloys exhibit only minor changes in mechanical properties and surface layer structure, as well as minimal geometric distortions in the cut. The zone with reduced magnesium content in the aluminum alloy does not exceed 0.5 mm from the cut surface, while in bronze, there is virtually no change in chemical composition. Both alloys show the presence of oxygen only on the cut surface without the formation of an oxide layer. In contrast, the quality of the Ti-5Al-5Mo-5V titanium alloy cut is signifi cantly lower. Due to the higher melting temperature, achieving full penetration of the plate is more challenging, and signifi cant edge distortion can be observed in the lower part of the plate. A substantial oxide layer forms on the surface, within which microcracks develop during cooling. This necessitates the requirement for shot blasting post-processing of the titanium alloy after cutting when air is used as the plasma-forming gas, or alternatively, replacing air with nitrogen. It is also noteworthy that in the upper part of the cut zone, where metal displacement from the kerf is more effi cient, the oxide layer is relatively thin. Cutting in air with additional water injection for the titanium alloy can also be employed but would likely require higher arc power and gas pressure. a b c d Fig. 11. Microhardness (a), change in oxygen content (b) in the surface layers of titanium alloy Ti-5Al-5Mo-5V and the results of X-ray analysis of the base metal (c) and the cut surface (d)
OBRABOTKAMETALLOV TECHNOLOGY Vol. 26 No. 4 2024 References 1. Levichev N., Tomás García A., Dewil R., Dufl ou J.R. A virtual sensing approach for quality and productivity optimization in laser fl ame cutting. The International Journal of Advanced Manufacturing Technology, 2022, vol. 121, pp. 6799–6810. DOI: 10.1007/s00170-022-09750-8. 2. Barsukov G.V., Selemenev M.F., Zhuravleva T.A., Kravchenko I.N., Selemeneva E.M., Barmina O.V. Infl uence of the parameters of chemical thermal treatment of copper slag particles on the quality of hydroabrasive cutting. Journal of Machinery Manufacture and Reliability, 2023, vol. 52, pp. 679–686. DOI: 10.1134/S1052618823070075. 3. Barsukov G., Zhuravleva T., Kozhus O. Quality of hydroabrasive waterjet cutting machinability. Procedia Engineering, 2017, vol. 206, pp. 1034–1038. DOI: 10.1016/j.proeng.2017.10.590. 4. Wei J., He W., Lin C., Zhang J., Chen J., Xiao J., Xu J. Optimizing process parameters of in-situ laser assisted cutting of glass-ceramic by applying hybrid machine learning models. Advanced Engineering Informatics, 2024, vol. 62, p. 102590. DOI: 10.1016/j.aei.2024.102590. 5. Shulyat’ev V.B., Gulov M.A., Karpov E.V., Malikov A.G., Boiko K.R. Laser cutting of aluminum alloys using pulsed radiation from a CO2 laser under conditions of an optical discharge in an argon jet. Bulletin of the Lebedev Physics Institute, 2023, vol. 50, pp. S1075–S1078. DOI: 10.3103/S1068335623220116. 6. He G.-J., Gu L., Zhu Y.-M., Chen J.-P., Zhao W.-S., Rajurkar K.P. Electrical arc contour cutting based on a compound arc breaking mechanism. Advances in Manufacturing, 2022, vol. 10 (4), pp. 583–595. DOI: 10.1007/ s40436-022-00406-0. 7. Sharma D.N., Kumar J.R. Optimization of dross formation rate in plasma arc cutting process by response surface method. Materials Today: Proceedings, 2020, vol. 32, pp. 354–357. DOI: 10.1016/j.matpr.2020.01.605. 8. Ilii S.M., Coteata M. Plasma arc cutting cost. International Journal of Material Forming, 2009, vol. 2, pp. 689– 692. DOI: 10.1007/s12289-009-0588-4. 9. Cinar Z., Asmael M., Zeeshan Q. Developments in plasma arc cutting (PAC) of steel alloys: a review. Jurnal Kejuruteraan, 2018, vol. 30, pp. 7–16. DOI: 10.17576/jkukm-2018-30(1)-01. 10. Barcelos M.B., Almeida D.T. de, Tusset F., Scheuer C.J. Performance analysis of conventional and high-feed turning tools in machining the thermally aff ected zone after plasma arc cutting of low carbon manganese-alloyed steel. Journal of Manufacturing Processes, 2024, vol. 115, pp. 18–39. DOI: 10.1016/j.jmapro.2024.01.08. 11. Akkurt A. The eff ect of cutting process on surface microstructure and hardness of pure andAl 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. 12. Gariboldi E., Previtali B. High tolerance plasma arc cutting of commercially pure titanium. Journal of Materials Processing Technology, 2005, vol. 160, pp. 77–89. DOI: 10.1016/j.jmatprotec.2004.04.366. 13. Grinenko A.V., Knyazhev E.O., Chumaevskii A.V., Nikolaeva A.V., Panfi lov A.O., Cheremnov A.M., Zhukov L.L., Gusarova A.V., Sokolov P.S., Gurianov D.A., Rubtsov V.E., Kolubaev E.A. Structural features and morphology of surface layers of AA2024 and AA5056 aluminum alloys during plasma cutting. Russian Physics Journal, 2023, vol. 66, pp. 925–933. DOI: 10.1007/s11182-023-03025-9. 14. Rubtsov V.E., Panfi lov A.O., Knyazhev E.O., Nikolaeva A.V., Cheremnov A.M., Gusarova A.V., Beloborodov V.A., Chumaevskii A.V., Ivanov A.N. Development of plasma cutting technique for C1220 copper, AA2024 aluminum alloy, and Ti-1,5Al-1,0Mn titanium alloy using a plasma torch with reverse polarity. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2022, vol. 24, no. 4, pp. 33–52. DOI: 10.17212/1994-6309-2022-24.4-33-52. 15. Sidorov E.A., Grinenko A.V., Chumaevsky A.V., Panfi lov A.O., Knyazhev E.O., Nikolaeva A.V., CheremnovA.M., Rubtsov V.E., Utyaganova V.R., Osipovich K.S., Kolubaev E.A. Patterns of reverse-polarity plasma torches wear during cutting of thick rolled sheets. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2024, vol. 26, no. 3, pp. 149–162. DOI: 10.17212/1994-6309-2024-26.3-149-162. 16. Chumaevskii A.V., Nikolaeva A.V., Grinenko A.V., Panfi lov A.O., Knyazhev E.O., Cheremnov A.M., Utyaganova V.R., Beloborodov V.A., Sokolov P.S., Gurianov D.A., Kolubaev E.A. Structure formation in surface layers of aluminum and titanium alloys during plasma cutting. Physical Mesomechanics, 2023, vol. 26, pp. 711–721. DOI: 10.1134/S1029959923060103. 17. Boulos M.I., Fauchais P., Pfender E. Plasma torches for cutting, welding and PTA coating. Handbook of thermal plasmas. Cham, Springer, 2023. DOI: 10.1007/978-3-319-12183-3_47-2. 18. Grinenko A.V., Chumaevskii A.V., Knjazhev E.O., Gurianov D.A., Sidorov E.A., Kolubaev E.A. Infl uence of reverse-polarity plasma cutting parameters on structure and surface roughness of aluminum alloys. Russian Physics Journal, 2024, vol. 67 (9), pp. 1287–1293. DOI: 10.1007/s11182-024-03246-6.
OBRABOTKAMETALLOV Vol. 26 No. 4 2024 TECHNOLOGY 19. Rubtsov V.E., Panfi lov A.O., Knyazhev E.O., Nikolaeva A.V., Cheremnov A.M., Gusarova A.V., Beloborodov V.A., Chumaevskii A.V., Grinenko A.V., Kolubaev E.A. Infl uence of high-energy impact during plasma cutting on structure and properties of surface layers of aluminum and titanium alloys. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2023, vol. 25, no. 4, pp. 216–231. DOI: 10.17212/1994-6309-2023-25.4-216-231. 20. Shchitsyn V.Yu., Yazovskikh V.M. Eff ect of polarity on the heat input into the nozzle of a plasma torch. Welding International, 2002, vol. 16 (6), pp. 485–487. DOI: 10.1080/09507110209549563. 21. Matushkina I., Anakhov S., Pyckin Yu. Design of a new gas-dynamic stabilization system for a metalcutting plasma torch. Journal of Physics: Conference Series, 2021, vol. 2094, p. 042075. DOI: 10.1088/17426596/2094/4/042075. 22. Kudrna L., Fries J., Merta M. Infl uences on plasma cutting quality on CNC machine. Multidisciplinary Aspects of Production Engineering, 2019, vol. 2 (1), pp. 108–117. DOI: 10.2478/mape-2019-0011. 23. Gostimirović M., Rodic D., Sekulić M., Aleksic A. An experimental analysis of cutting quality in plasma arc machining. Advanced Technologies & Materials, 2020, vol. 45 (1), pp. 1–8. DOI: 10.24867/ATM-2020-1-001. Confl icts of Interest The authors declare no confl ict of interest. © 2024 The Authors. Published by Novosibirsk State Technical University. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0).
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