Vol. 26 No. 2 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. 2 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. 2 2024 5 CONTENTS OBRABOTKAMETALLOV TECHNOLOGY Gaikwad V., Chinchanikar S. Investigations on ultrasonic vibration-assisted friction stir welded AA7075 joints: Mechanical properties and fracture analysis........................................................................................................................ 6 Sirota V.V., Zaitsev S.V., Limarenko M.V., Prokhorenkov D.S., Lebedev M.S., Churikov A.S., Dan'shin A.L. Preparation of coatings with high infrared emissivity.......................................................................................................... 23 Babaev A.S., Kozlov V.N., Semenov A.R., Shevchuk A.S., Ovcharenko V.A., Sudarev E.A. Investigation of cutting forces and machinability during milling of corrosion-resistant powder steel produced by laser metal deposition............. 38 Dolgova S.V., Malikov A.G., Golyshev A.A., Nikulina A.A. The eff ect of laser surfacing modes on the geometrical characteristics of the single laser tracks............................................................................................................................... 57 Karlina Y.I., Kononenko R.V., Popov M.A., Deryugin F.F., Byankin V.E. Assessment of welding engineering properties of basic type electrode coatings of diff erent electrode manufacturers for welding of pipe parts and assemblies of heat exchange surfaces of boiler units............................................................................................................................. 71 Yanpolskiy V.V., Ivanova M.V., Nasonova A.A., Yanyushkin A.S. Determination of the rate of electrochemical dissolution of U10A steel under ECM conditions with a stationary cathode-tool............................................................... 95 EQUIPMENT. INSTRUMENTS Zakovorotny V.L., Gvindjiliya V.E. The study of vibration disturbance mapping in the geometry of the surface formed by turning............................................................................................................................................................................. 107 Gasanov B.G., Konko N.A., Baev S.S. Study of the kinetics of forming of spherical sliding bearing parts made of corrosion-resistant steels by die forging of porous blanks............................................................................................... 127 Gvindjiliya V.E., Fominov E.V., Moiseev D.V., Gamaleeva E.I. Infl uence of dynamic characteristics of the turning process on the workpiece surface roughness........................................................................................................................ 143 Lobanov D.V., Skeeba V.Yu., Golyushov I.S., Smirnov V.M., Zverev E.A. Design simulation of modular abrasive tool........................................................................................................................................................................................ 158 MATERIAL SCIENCE EroshenkoA.Yu., Legostaeva E.V., Glukhov I.A., Uvarkin P.V., TolmachevA.I., Sharkeev Yu.P. Thermal stability of extruded Mg-Y-Nd alloy structure.................................................................................................................................. 174 Bazaleeva K.O., Safarova D.E., Ponkratova Yu.Yu., Lugovoi M.E., Tsvetkova E.V., Alekseev A.V., Zhelezni M.V., Logachev I.A., Baskov F.A. The infl uence of technological parameters of the laser engineered net shaping process on the quality of the formed object from titanium alloy VT23......................................................... 186 Efi movich I.A., Zolotukhin I.S. Oxidation temperatures of WC-Co cemented tungsten carbides....................................... 199 Pribytkov G.A., Baranovskiy A.V., Firsina I.A., Akimov K.O., Krivopalov V.P. Study of Fe-matrix composites with carbide strengthening, formed by sintering of iron titanides and carbon mechanically activated mixtures................ 212 EDITORIALMATERIALS 224 FOUNDERS MATERIALS 235 CONTENTS
OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 2 2024 The influence of technological parameters of the laser engineered net shaping process on the quality of the formed object from titanium alloy VT23 Ksenia Bazaleeva 1, a, *, Daria Safarova 1, b, Yulia Ponkratova 1, c, Maxim Lugovoi 1, d, Elena Tsvetkova 1, e, Andrei Alekseev 1, f, Mark Zhelezni 1, j, Ivan Logachev 2, h, Fedor Baskov 2, i 1 Peoples’ Friendship University of Russia named after Patrice Lumumba, 6 Miklukho-Maklaya st., Moscow, 117198, Russian Federation 2 The National University of Science and Technology MISIS, 4 Leninskiy Pr., Moscow, 119049, Russian Federation a https://orcid.org/0000-0002-6205-3154, bazaleeva-ko@rudn.ru; b https://orcid.org/0000-0002-2811-8292, safarova_de@pfur.ru; c https://orcid.org/0009-0000-1094-3529, ponkratova_yuyu@rudn.ru; d https://orcid.org/0009-0007-7160-7802, www111www6376@gmail.com; e https://orcid.org/0009-0002-8462-1818, tsvetkova-ev@rudn.ru; f https://orcid.org/0009-0008-7394-6370, alexeev-anvs@rudn.ru; j https://orcid.org/0000-0003-3821-6790, markiron@mail.ru; h https://orcid.org/0000-0002-8216-1451, logachev.ia@misis.ru; i https://orcid.org/0000-0001-6238-4378, baskov.fa@misis.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. 2 pp. 186–198 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2024-26.2-186-198 ART I CLE I NFO Article history: Received: 25 January 2024 Revised: 19 February 2024 Accepted: 20 March 2024 Available online: 15 June 2024 Keywords: Laser engineered net shaping Titanium alloys Technological parameters Phase-structural state ABSTRACT Introduction. Laser engineered net shaping (LENS) or Direct metal deposition (DMD) is considered as a promising method for manufacturing products of complex configurations from titanium-based alloys, as it allows minimizing the use of machining and loss of material to waste. Currently, neither the LENS technological process of titanium alloy VT23 has not been developed, nor the structural features of the alloy after LENS have not been studied, which will make it possible to determine the scope of application of the material after LENS. The purpose of this study is to determine optimal modes of the LENS process for manufacturing of quality parts from titanium alloy VT23. Methodology. The alloy specimens obtained with laser power 700÷1300 W in increments of 100 W and scanning speed 600÷1,000 mm/min in increments of 200 mm/min and distance between adjacent laser tracks 0.5–0.9L (L — track width) in increments of 0.2L were analyzed in the study. The elemental composition of the powder material was studied by X-ray fluorescence analysis and reducing combustion in a gas analyzer, the structure of the objects obtained by LENS was analyzed by metallographic and X-ray phase analysis methods as well as microhardness was determined. Results and discussion. It is established that high-quality objects without cracks, with low porosity can be synthesized from VT23 alloy by LENS method using the following modes: laser power 700÷1100 W, scanning speed 800–1,000 mm/min, track spacing 0.5–0.7 of the individual track width L. It is shown that after all investigated LENS modes, the VT23 alloy had a dispersed (α+β) structure of the “basket weave” type. It is revealed that regardless of LENS mode the amount of β-phase in the alloy structure is about 30 %. It is shown that the microhardness of the deposited material does not depend on LENS modes and is 460 HV. For citation: Bazaleeva K.O., Safarova D.E., Ponkratova Yu.Yu., Lugovoi M.E., Tsvetkova E.V., AlekseevA.V., Zhelezni M.V., Logachev I.A., Baskov F.A. The influence of technological parameters of the laser engineered net shaping process on the quality of the formed object from titanium alloy VT23. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2024, vol. 26, no. 2, pp. 186–198. DOI: 10.17212/1994-6309-2024-26.2-186-198. (In Russian). ______ * Corresponding author Bazaleeva Ksenia O., Ph.D. (Engineering) Peoples’ Friendship University of Russia named after Patrice Lumumba, 6 Miklukho-Maklaya st., 117198, Moscow, Russian Federation Tel.: +7 905 760-12-32, e-mail: bazaleeva-ko@rudn.ru Introduction Titanium alloys are known for its high specific strength, corrosion resistance, and crack resistance and found applications in various industrial sectors, including aerospace [1]. Since many components of aircraft have a complex configurations, laser engineered net shaping (LENS) is considered as a promising technology for its production [2–5]. Another reason for utilizing LENS technology in manufacturing parts from titanium alloys is that these materials are difficult to process mechanically due to its high strength
OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 2 2024 and low thermal conductivity, while LENS allows the formation of complex-profiled parts with minimal mechanical processing. Moreover, diminishing mechanical processing helps reduce the amount of expensive alloy waste. It is known that the quality of the objects manufactured by LENS depends on its technological parameters. Quality in this case implies the absence of macrodefects like cracks and pores that can form during laser remelting of the powder material. In [6–13] authors optimize the LENS technological parameters for manufacturing parts from titanium alloys by varying laser power, scanning speed, powder feed rate, laser spot diameter, distance between laser tracks and laser operating mode (pulse/continuous) [5]. However, the practical application of modes developed by other researchers is mainly hindered by two reasons. The first reason is that most researches have been conducted on the titanium alloy Ti-6Al-4V [4–9] and significantly less studies have been devoted to the development of LENS technology for titanium alloys of different compositions (Ti-Al-Sn-Zr-Mo [10], Ti-Al-Sn-Zr-Mo-Cr [11], Ti-Al-Mo-Zr-Si [12]), and there are almost no studies on LENS of the Ti-5Al-4V-2.5Mo-1Cr-0.7Fe-0.1Si alloy (VT23). However, it is known that changes in the physical properties of the alloy affect the powder material remelting processes, and the alloy composition have to be taken into account. Moreover, LENS is a multi-parameter process, while most papers only provide values for basic parameters. Thermal conditions of powder remelting significantly depend on the working setup, the initial state of the powder material and even slight changes in re-melting conditions can result in shift of the optimal parameter range. Thus, developing modes of manufacturing high-quality objects of a given composition is an integral part of LENS technology. The purpose of this work was to develop LENS modes on the InssTek MX-Grande printer for the formation of high-quality products from a titanium alloy (VT23). To achieve this goal, the following tasks were solved during the research: - determination of intervals of the LENS technological parameters (laser radiation power, scanning speed and distance between laser tracks), which make it possible to form a structure without cracks, with minimal porosity and surface roughness, with penetration into the lower layer less than 40 %; - metallographic study of the structure formed in the alloy during LENS; - determination of the phase composition of the alloy after LENS; - study of the influence of the LENS technological parameters on the microhardness of the obtained material. Methods The objects of the study were specimens manufactured by LENS from titanium alloy VT23. X-ray fluorescence spectral analysis was used to assess the elemental composition of the initial titanium powder, and the concentrations of gas impurities in the powder were determined by the reduction burning method (Table 1). The chemical composition of the VT23 powder, including the concentrations of gas impurities, corresponded to OST 1-90013-81 [14]. The dispersion of the powder ranged from 40 to 100 µm. The phase composition of the initial powder material was determined by X-ray diffraction method and consisted of a α-Ti solid solution with a cubic crystal lattice and titanium oxide TiO2 (rutile) phase with a tetragonal crystal lattice while β phase was not detected (Figure 1). The presence of the TiO2 phase in the diffraction pattern is likely associated with a high proportion of the surface oxide layer in the irradiated volume of a dispersed (less than 100 µm) powder material during X-ray analysis. LENS process was carried out on the InssTek MX-Grande laser system in an Ar protective atmosphere, and the LENS modes are provided in Table 2. The selection of LENS modes that allow forming parts of satisfactory quality was carried out in several steps. In the first step, the selection is based on the geometric parameters of the cross-section of a single laser track. In the second step, the characteristics of monolayers, i.e., objects with a height of one deposited layer, are considered, and in the final step, the quality of the volumetric specimen is analyzed.
OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 2 2024 The evaluation of the quality of a single laser track was conducted according to the following criteria: – the track shape coefficient f h f L = , where h is the height of the track above the substrate; L is the width of the track (Fig. 2); Fig. 1. X-ray diffraction pattern of the initial powder Ta b l e 1 Chemical composition of the experimental powder Mass fraction of chemical elements, % Ti Al V Mo Cr Fe O H N C bal. 4.8 4.5 2.6 1.2 0.4 0.12 0.004 0.018 0.03 Ta b l e 2 LENS modes Powder feed rate 10 g/min Ar gas supply coaxial – 10 l/min transport – 3.5 l/min shield – 20 l/min Nozzle height above surface 9 mm Laser spot diameter 1,800 μm Laser power 700…1.300 W, step 100 W Scanning speed 600…1.000 mm/min, step 200 mm/min
OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 2 2024 Ta b l e 3 Geometric parameters of a single laser track evaluation criteria Parameter Valid value Shape factor (f) 0.2…0.33 Penetration ratio (d) 0.1…0.4 Track width (L) 1.7…3.0 mm Angle at the base (q) < 90° Fig. 2. Shape of the track formed by a laser power of 1.000 W and laser scanning speed of 1.000 mm/min – melting coefficient d p p h S d S S = + , where Sp and Sh are the areas of the track below and above the substrate surface; – track width L; – angle at the base of the track θ [15, 16–19]. The acceptable values of these characteristics are provided in Table 3. Additionally, the absence of cracks is one of the important criteria. During the formation of monolayers, the distance between adjacent tracks varied in the range from 0.5L to 0.9L, where L is the width of the track determined in the previous step. The requirements for the geometric parameters of the mono-layers were as follows: the height variation of the mono-layer should not exceed 30 % of its maximum height, and the depth of melting should be less than 2/3 of the layer height. For volumetric specimens manufactured under different technological modes, the presence of cracks and large (more than 1–2 µm) pores in longitudinal and transverse sections was monitored. The microstructure of the manufactured specimens was investigated using an inverted metallographic microscope Olympus GX-51. For optical metallography, the specimens were embedded in resin using an automatic press Struers CitoPress-20 and prepared on a grinding-polishing station Struers Tegramin 25. Chemical etching in a aqueous solution of hydrofluoric and nitric acids was used to reveal the structure: 3 ml HF, 15 ml HNO3, 82 ml H2O. The microhardness of the specimens was evaluated using the Vickers method on a microhardness tester Pruftechnik KB50 SR. The indentation load was 1.9 N (200 g), with a measurement error of no more than 10 %.
OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 2 2024 X-ray diffraction analysis was conducted in the Bruker D8 Advance diffractometer with Bragg-Brentano focusing scheme in Cu Kα radiation in the range of diffraction angles 2θ = 30°–100° with a step of Δ2θ = 0.07° and exposure time of 2 seconds per point. The tube voltage was 40 kV, and the tube current was 35 mA. A semiconductor multichannel detector was used, with a 2 mm slit and Soller slit installed on the tube, and only a Soller slit on the detector. During the data collection, the specimens were rotated at a speed of 60 rpm. The spectrum processing was conducted using Diffrac.Eva and Diffrac.Topas software. For X-ray phase analysis, the specimens were electropolished on a Struers LectroPol-5 in A2 electrolyte (78 mL HClO4, 90 mL distilled water, 730 mL C2H6O, 100 mL C6H14O2) for 15 min at 10 V. Results and discussion According to metallographic analysis, the tracks obtained under all experimental modes (Table 2) are free from cracks, exhibit minimal porosity, and have defect-free boundaries with the substrate material (Fig. 2). A heat affected zone (HAZ) with a width of approximately 0.50 ± 0.05 mm is observed at the track boundary. Analysis the dependence of the track shape coefficient f on power revealed that at a scanning speed of 600 mm/min, the coefficient f exceeds the permissible range (Figure 3). The geometric parameters of the track obtained at scanning speeds of 800 and 1.00 mm/min meet the requirements for the shape coefficient, bead width, and melting coefficient of the track. The angle at the base of the track is less than 90 degrees for almost all experimental laser deposition modes. a b c Fig. 3. Dependences of the track width (a), penetration ratio (b), track shape factor (c) on the laser power (green area – range of accepted values) Microhardness of the tracks manufactured under different modes varies in the range from 386 to 499 HV (Fig. 4). From the graphs, it is evident that increasing the laser power P results in an increase in hardness, while increasing the scanning speed also results in hardness growth, although this effect is minor. It is known that during the LENS process, the material cooling rate is relatively high, which may lead to the formation of a dispersed (α + β) structure and the martensite formation. It can be assumed that the increase in hardness at high laser power is associated with an increase in the temperature gradient. Based on the track analysis, seven LENS modes were selected (Table 4). The structures of the grown monolayers are presented in Figure 5. A compliance assessment of the monolayers with the specified criteria is shown in the graphs in Figure 6. The manufacturing mode with a distance of 0.9L between adjacent tracks is considered impractical as height variation in some modes is close to 90 %. These specimens consisted not of monolithic layers but of a set of individual tracks. Specimens with a track spacing of 0.5L and 0.7L have approximately the same geometry. The height variation in both cases differs slightly and ranges from 10 to 20 %. It should be noted that at a spacing of 0.5L, the layer height was smaller for all LENS modes compared to 0.7L (Fig. 6, b). This is likely due to the
OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 2 2024 Fig. 4. Dependence of microhardness of single tracks on laser power for different scanning speeds Ta b l e 4 Laser deposition modes selected according to the shape of a single track Scanning speed V, mm/min 700 800 900 1.000 1.100 1.200 1.300 Laser power P, W 800 1.000 1.000 1.000 1.000 1.000 800 Fig. 5. Structure of monolayers obtained by the LENS method with a scanning speed of 1.000 mm/min, power of 1.000 W and different distances between tracks: a – 0.5L; b – 0.7L; c – 0.9L a b c fact that with a track spacing of 0.5L, the forming molten pool captures more material from the neighboring solidified track, which may lead to an increase in the proportion of dispersed powder on it. In other words, these dependencies indicate that the powder material is absorbed to a greater extent with a track spacing of 0.7L. It is also worth noting that when the laser power exceeds 1.000 W at a scanning speed of 1.000 mm/min, an increase in the porosity of the monolayers is observed.
OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 2 2024 The monolayers microhardness is slightly higher than the one of the previously obtained tracks and amounts to 487 ± 15 HV, while the microhardness value of the monolayer does not depend on the deposition mode (Fig. 7). This result is likely due to the fact that during the laser deposition of multiple tracks, due to the re-heating of the already surfaced material, aging processes occur, i.e., the breakdown of supersaturated solid solutions, resulting in an increase of alloy microhardness. The modes providing the most uniform layer and the absence of macrodefects were selected to create bulk specimens (Table 5). a b c Fig. 6. Effect of the distance between tracks on the relative height difference (∆h/h) (a), monolayer height (h) (b), ratio of penetration depth to monolayer height (p/h) depending on laser power (c) (green area – area of acceptable values) Fig. 7. Dependence of microhardness of monolayers and bulk specimens on laser power Ta b l e 5 Modes selected according to the structure of monolayers Laser power P, W 700 700 800 800 900 1.000 1.100 Scanning speed V, mm/min 800 800 1.000 1.000 1.000 1.000 1.000 Distance between tracks 0.5L 0.7L 0.5L 0.7L 0.7L 0.7L 0.7L
OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 2 2024 а b Fig. 8. Microstructure of VT23 alloy after LENS (P = 1,000 W; track distance 0.7L): a – laser scanning plane; b – cross section of the specimen Fig. 9. X-ray diffraction pattern of a bulk specimen at P = 700 W and 0.5L The study of the microstructure of the obtained bulk specimens allows us to conclude that there are no macro-defects. After LENS at a laser power of 1,000 W, the α-phase is observed in the form of areas of the so-called “basket weave” and areas of a mesh around primary β-grains (Fig. 8). Such structures are characteristic of this alloy both in the quenched state and after LENS [20–23]. Large (~ 100 μm) equiaxed regions of primary β-phase crystals are observed in the scanning plane. Similar structures were observed at other LENS modes as well. When analyzing the dependence of the microhardness of bulk specimens on the deposition mode, it was found that the hardness level at all modes is approximately the same, measuring 457 ± 23 HV (Fig. 7). Figure 9 presents the results of X-ray phase analysis. All specimens obtained by LENS modes exhibit (α + β) phase composition, where α and β are phases with BCC and FCC crystal lattices, respectively. Since the diffraction peaks of α’-martensite coincide with the peaks of the α-phase, it is not possible to definitively determine its presence in the structure based on the diffraction pattern. It is found that the amount of β-phase constitutes approximately 30 %.
OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 2 2024 Conclusion 1. The determination of the LENS modes of VT23 alloy is conducted, allowing the synthesis of objects without cracks, with minimal both porosity and surface roughness, with the specified level of fusion coefficient: laser power P = 700…1.100 W; scanning speed v = 800…1,000 mm/min; the distance between tracks is 0.5…0.7 of the width of the track. 2. Optical metallography revealed that after all experimental LENS modes, the structure of the titanium alloy resemble a “basket weave” pattern with dispersed α- and β-phase needle-shaped grains. 3. According to X-ray phase analysis, phase composition of VT23 alloy doesn’t depend on modes and consists of 70 % α-phase and 30 % β-phase. 4. Durometric analysis showed that increasing the laser power results in the microhardness increase of the individual tracks: for a scanning speed of 800 mm/min, increasing the power from 700 to 1.300 W results in the hardness increasing from 390 to 500 HV. However, the increase in power practically does not affect the hardness of monolayers and bulk specimens, maintaining it at an average level of 460 HV. References 1. Belov S.P., Brun M.Ya., Glazunov S.G., Kolachev B.A. Metallovedenie titana i ego splavov [Metallurgy of titanium and its alloys]. Moscow, Metallurgiya Publ., 1992. 352 p. 2. Liu Z., He B., Lyu T., Zou Y. A review on additive manufacturing of titanium alloys for aerospace applications: Directed energy deposition and beyond Ti-6Al-4V. Jom, 2021, vol. 73, pp. 1804–1818. DOI: 10.1007/s11837-02104670-6. 3. Dang L., He X., Tang D., Wu B., Li Y. A fatigue life posterior analysis approach for laser-directed energy deposition Ti-6Al-4V alloy based on pore-induced failures by kernel ridge. Engineering Fracture Mechanics, 2023, vol. 289, p. 109433. DOI: 10.1016/j.engfracmech.2023.109433. 4. Ronzhin D.A., Grigoryants A.G., Kholopov A.A. Vliyanie tekhnologicheskikh parametrov na strukturu metalla izdelii, poluchennykh metodom pryamogo lazernogo vyrashchivaniya iz titanovogo poroshka VT6 [Effect of operational parameters on metal structure in products manufactured by direct laser deposition from VT6 titanium powder]. Izvestiya vysshikh uchebnykh zavedenii. Mashinostroenie = BMSTU Journal of Mechanical Engineering, 2022, no. 9 (750), pp. 30–42. 5. Ravi G.A., Qiu C., Attallah M.M. Microstructural control in a Ti-based alloy by changing laser processing mode and power during direct laser deposition. Materials Letters, 2016, vol. 179, pp. 104–108. DOI: 10.1016/j. matlet.2016.05.038. 6. MahamoodR.M.,Akinlabi E.T. Laser power and powder flowrate influence on themetallurgy andmicrohardness of laser metal deposited titanium alloy. Materials Today: Proceedings, 2017, vol. 4 (2), pp. 3678–3684. 7. Safarova D.E., Lugovoi M.E., Ponkratova Yu.Yu., Bazaleeva K.O. [Development of a direct laser growth mode for titanium alloy VT23]. VIII Vserossiiskaya konferentsiya po nanomaterialam «NANO 2023» [Proceedings of the VIII All-Russian Conference on Nanomaterials “NANO 2023”]. Moscow, 2023, pp. 242–243. (In Russian). 8. Paydas H., Mertens A., Carrus R., Lecomte-Beckers J., Tchuindjang J.T. Laser cladding as repair technology for Ti–6Al–4V alloy: Influence of building strategy on microstructure and hardness. Materials & Design, 2015, vol. 85, pp. 497–510. DOI: 10.1016/j.matdes.2015.07.035. 9. Fatoba O.S., Akinlabi E.T., Akinlabi S.A., Erinosho M.F. Influence of process parameters on the mechanical properties of laser deposited Ti-6Al-4V alloy. Taguchi and response surface model approach. Materials Today: Proceedings, 2018, vol. 5 (9), pp. 19181–19190. DOI: 10.1016/j.matpr.2018.06.273. 10. Song L., Xiao H., Ye J., Li S. Direct laser cladding of layer-band-free ultrafine Ti6Al4V alloy. Surface and Coatings Technology, 2016, vol. 307, pp. 761–771. DOI: 10.1016/j.surfcoat.2016.10.007. 11. Sinclair L., Clark S.J., Chen Y., Marussi S., Shah S., Magdysyuk O.V., Lee P.D. Sinter formation during directed energy deposition of titanium alloy powders. International Journal of Machine Tools and Manufacture, 2022, vol. 176, p. 103887. DOI: 10.1016/j.ijmachtools.2022.103887. 12. Liu Q. Wang Y., Zheng H., Tang K., Li H., Gong S. TC17 titanium alloy laser melting deposition repair process and properties. Optics & Laser Technology, 2016, vol. 82. pp. 1–9. DOI: 10.1016/j.optlastec.2016.02.013. 13. Wang T., Zhu Y.Y., Zhang S.Q., Tang H.B., Wang H.M. Grain morphology evolution behavior of titanium alloy components during laser melting deposition additive manufacturing. Journal of Alloys and Compounds, 2015, vol. 632, pp. 505–513. DOI: 10.1016/j.jallcom.2015.01.256.
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