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The structure of the base metal and weld metal after electron-beam welding (EBW) of the intermetallic titanium alloy Ti−28Al−7Nb−2Mo−2Cr (wt.%) obtained by the electron-beam melting method is studied. The macrostructure of the Ti−28Al−7Nb−2Mo−2Cr alloy ingot is characterized by grains close to equiaxed with a grain size of 8–9 points. As shown, the microstructure of the cast metal of the Ti−28Al−7Nb−2Mo−2Cr alloy consists of a matrix bright γ-phase alternating with sections of a two-phase (γ + α2) lamellar structure up to 50 µm in size, with a lamellae thickness of about 1 µm, and of the ordered β-phase, which forms a mesh pattern against the background of the matrix. As established, the intragranular structure of the metal of the welded joint after EBW with local heat treatment (LHT) differs from the structure of the base metal and consists of small (up to 20 µm) areas with a (γ + α2) lamellar structure against the background of a light matrix γ-phase with a network of elongated particles of 30−80 µm long and 1−3 µm thick. [ABSTRACT FROM AUTHOR] more...

The influence of furnace annealing on the structure of cast metal in 200 mm ingots from intermetallic titanium alloy Ti–28Al–7Nb–2Mo–2Cr produced by electron beam melting and of its welded joints produced by the method of electron beam welding was determined. It is established than the metal of 200 mm Ti–28Al–7Nb–2Cr–2Mo ingots based on titanium aluminide is readily welded under the conditions of application of such technological measures as preheating and local heat treatment. It is shown that annealing at the temperature of 1260 °C for 10 h led to formation of a uniform microstructure in the base metal, HAZ and weld metal, decomposition of the duplex structure and absence of regions with a two-phase (γ+α2)-lamel structure. Room temperature strength of welded joints after annealing is equal to 746 MPa or 98 % of base metal strength. [ABSTRACT FROM AUTHOR] more...

Work has been performed on optimization of the technological scheme of producing ingots for consumable electrodes with a stable chemical composition and properties. The paper presents the results of studying an ingot of 195 mm diameter from a titanium aluminide-based alloy of Ti–28Al–7Nb–2Mo system, made by double electron beam remelting. Further ingot remelting in the arc furnace was performed, which allowed producing a homogeneous and defectfree ingot of an optimal composition of Ti–28Al–7Nb–2Mo–0.3 (Y, Re, B). The influence of modifying on the structure and properties was studied. It was determined that addition of surfactants promotes refining of the structural components and improvement of the alloy mechanical properties. [ABSTRACT FROM AUTHOR] more...

In order to implement the electron beam melting technologies the E.O. Paton Electric Welding Institute of NASU developed a multifunctional electron beam unit UE-5810 of megawatt class, designed for producing ingots of titanium and its alloys of up to 20 tons weight. Description of a multi-purpose universal electron beam unit UE-5810 and its specification are given. Functional features of the components of the unit, technological fixtures and electron gun are described. Electron beam unit UE-5810 is a reliable highly efficient installation of industrial type for melting highly reactive metals and alloys, as well as treatment of the produced ingots by surface melting. 12 Ref., 8 Fig. [ABSTRACT FROM AUTHOR] more...

Proceeding from the results of the performed package of research work, it was established that the chemical composition of metal in the surface-melted layer of high-temperature titanium alloy VT9 corresponds to standard requirements; and a lowering of aluminium content, an alloying element with vapour pressure higher, and an increase in the content of molybdenum and zirconium, alloying elements with vapour pressure lower than that of titanium, is observed. Investigations of the surface-melted layer showed that the depth of penetration of the surface layer in ingots of high-temperature titanium alloy VT9 of 600 mm diameter reaches 8 mm, the ingot surface is high-quality mirror-like with characteristic vacuum etching, even microrelief without cracks, tears or lacks-of-fusion, its roughness is in the range of 3…4 class at waviness of 0.2…0.6 mm. The surface-melted layer of the ingot has a finer structure, compared to base metal, and it consists of areas with isolated α-plates of 1.0…2.5 μm thickness, where the α-plates are gathered into colonies of 10…50 μm width, and the gaps between them are taken up by dispersed particles of 1…2 μm size, which can be the products of metastable phase decomposition. Ref. 13, Tabl. 1, Fig. 10. [ABSTRACT FROM AUTHOR] more...

The structure and mechanical properties of high-temperature titanium alloy of Ti–Al–Zr–Si–Mo–Nb–Sn system after hot deformation treatment by various modes were studied. It was found that metal deformation treatment performed in the upper part of the region of (α+β)-phase existence, ensures an increase of material ductility by almost 30 times, compared with lithium, and high strength values, both at room and at working temperature of 600 °С. [ABSTRACT FROM AUTHOR] more...

A complex of research work was performed on the base of EBM technology to produce high-strength complex-alloyed titanium alloys of Ti‒Al‒Zr‒Si‒Mo‒Nb‒Sn system with silicon content, higher than the thermodynamically stable value in the solid solution. Alloys of this system are promising for creation of a new class of materials with a high level of heat-resistant characteristics. It is shown that EBM allows producing ingots of high-temperature titanium alloys of Ti‒Al‒Zr‒ Si‒Mo‒Nb‒Sn system, which are characterized by sufficient chemical homogeneity and absence of casting defects. It is found that tin presence lowers silicon solubility in the test alloys and intensifies silicide release. Here the structure is also refined. It is found that additional alloying elements influence silicon solubility in titanium, forming complex silicides of (Zr, Ti)5 Si (Ti, Zr)3 Si type in the test alloys. It is shown that the microstructure of the test cast alloys consists of platelike α-phase packets within primary β-grains, having different crystallographic orientation. Ref. 18, Fig. 8. [ABSTRACT FROM AUTHOR] more...

A mathematical model was developed of the processes of alloying element evaporation at cold-hearth electron beam melting of ingots of alloys based on titanium aluminide of Ti–Al–Nb–Cr–Mo alloying system that establishes the dependence of alloying element concentration in the ingot on technological parameters of melting and chemical composition of the initial charge. It is shown that the developed mathematical model adequately describes the real evaporation process at electron beam melting of titanium aluminide alloy. The regularities of alloying element evaporation at electron beam melting of alloys based on titanium aluminide of Ti–Al–Nb–Cr–Mo system were established, which allow predicting the chemical composition of the ingots and optimizing the technological parameters of melting. Ref. 21, Tabl. 2, Fig. 5. [ABSTRACT FROM AUTHOR] more...

The possibility of producing by electron beam melting the ingots of titanium aluminide of Ti–Al system, additionally alloyed by refractory elements, namely niobium, chromium and molybdenum, was studied. A procedure of adding the refractory elements was developed, and technological modes were calculated, which allow optimizing the alloying element evaporation during melting. Test melting of Ti–28Al–7Nb–2Mo–2Cr intermetallic alloy was conducted in UE-121 electron beam unit. An ingot of 200 mm diameter was produced and its quality, structure and mechanical properties were studied. Ref. 11, Tabl. 2, Fig. 5. [ABSTRACT FROM AUTHOR] more...

Complex works were performed to study the quality of wrought semi-finished products, manufactured from an ingot of VT9 titanium alloy. Electron beam remelting technology was used to produce ingots of 600 mm diameter and 1.5 m length, from which semi-finished products were manufactured in the form of hot-pressed rods of 315 mm diameter. Results of investigations of structurare and mechanical properties of semi-finished products in the form of hot-pressed rods are given. It is shown that the metal of the produced ingots and wrought semi-finished products meets the requirements of the standards after the respective heat treatment. Ref. 10, Tabl. 4, Fig. 3. [ABSTRACT FROM AUTHOR] more...

Copyright of Electrometallurgy Today / Sovremennaya Elektrometallurgiya is the property of International Association Welding (Paton Publishing House) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

Comprehensive research was performed on producing large-sized ingots of 1100 mm dia and up to 3 m length from Grade 2 titanium alloy by the method of cold-hearth electron beam melting in the production facilities of SC «SPC «Titan» of the E.O.Paton Electric Welding Institute of the NAS of Ukraine» in a multifunctional electron beam unit UE5810. It is shown that in production of large-sized titanium ingots by cold-hearth electron beam melting the energy losses for radiation and evaporation should be compensated by the efficiency of the melting process, taking into account the general metal losses for evaporation. As a result of the studies, it was determined that the content of impurity elements in the metal of the produced ingot meets the requirements of the standard, hydrogen concentration being not higher than 0.002 % that is 7 times smaller than the maximum value allowed by the standard, and no increased content of oxygen or nitrogen was found either in the ingot bottom or head parts. It is shown that the metal of the largesized titanium ingot produced by cold-hearth electron beam melting has no internal defects in the form of nonmetallic inclusions, pores or discontinuities, and no significant difference is observed between the macrostructure of the ingot central and peripheral zones, which is characteristic for ingots in vacuum arc remelting. Ref. 15, Tabl. 1, Fig. 6. [ABSTRACT FROM AUTHOR] more...

It is shown that when specifying the productivity of EBM process, the phenomenon of thermogravitational convection is a weighty factor that determines the thermal state of the ingot. A mathematical model of interrelated hydrodynamic and thermal processes in the crystallizing metal, taking into account the phenomena of thermogravitational convection, was formulated for a steady-state mode of the process of electron beam melting of titanium into a straight-through cylindrical crucible. The thermal state of the ingot was determined, as well as the position of the solidification front at continuous feeding of liquid titanium from the cold hearth into the crucible, depending on metal temperature at the inlet and speed of ingot drawing for laminar mode of hydrodynamic flow in the liquid pool. It is found that at increase of metal temperature at the inlet to the crucible in the studied range (2040…2100 К) shifting of the point of maximum pool depth from the ingot axis becomes smaller. Calculations within the constructed mathematical model were used to study the impact of the rate of liquid metal feed from the cold hearth into the crucible on the liquid pool shape and depth. It is found that at increase of ingot drawing rate by 30 % the liquid pool depth increases 1.5 times, and the point of maximum depth of the liquid pool becomes close to ingot axis. Ref. 10, Tabl. 1, Fig. 9. [ABSTRACT FROM AUTHOR] more...

Work on melting ingots of pseudo-β-alloy Ti–2.8Al–5.1Mo–4.9Fe and pseudo-α-alloy Ti–1.5Fe–0.4O was performed. Electron beam unit UE208M with a cold-hearth and portioned feed of liquid metal was used to produce ingots of a round cross-section of 110 mm diameter, which were deformed to 6 mm thickness. The structures of the rolled plates were studied. Metal structure of sparsely-doped alloy of Ti–2.8Al–5.1Mo–4.9Fe system consisted from equiaxed polyhedral β-grains, with dispersed particles of α-phase located in their volume, here the amount of β-phase can vary within 50…82 %, while the structure of pseudo-α-alloy Ti–1.5Fe–0.4O consisted of platelike α-phase, with β-phase located in the spaces between the plates. Dispersed particles of titanium-iron intermetallics of less than 1 μm size were observed in the structure of both the alloys. Precipitation of iron-based titanium intermetallics can be the cause for low values of ductility and brittle fracture of metal of sparsely-doped pseudo-β-alloy Ti–2.8Al–5.1Mo–4.9Fe. Strength of alloy Ti–1.5Fe–0.4O is as-rolled condition was on the level of 730 MPa. Strength of sparsely-doped alloy of Ti–2.8Al– 5.1Mo–4.9Fe system in as-rolled condition was on the level of 1015 MPa, while the values of impact toughness KCV and relative elongation were equal to 3…4 J/cm² and 1.9 %, respectively. Ref. 17, Tabl. 4, Fig. 9. [ABSTRACT FROM AUTHOR] more...

In order to achieve high mechanical characteristics of iron-based material, a modifier of highly-dispersed silicon carbide compound was used as master alloy that during electron beam melting provides a strengthened by nanoparticles structure of a material, suitable for further deformation processing. A nanosized powder was synthesized in the form of solid solution of carbon in silicon carbide, to create nanosized alloying modifiers for iron-based materials. A technology was developed for producing by electron beam melting iron-based ingots, alloyed by a highly-dispersed silicon carbide compound. Work was performed on producing 200 mm diameter iron ingots, with addition of 1, 2 and 3 % of synthesized nanosized alloying modifiers, based on silicon carbide. Thermal deformation processing of the ingots was conducted. The structure and properties of the produced material were studied. It was established that the produced materials based on iron with addition of nanosized silicon carbide are characterized by a dispersed size of the grains and nanosized carbide formations of platelike type. Increase of the concentration of nanosized silicon carbide from 1 to 3 % leads to formation of nanostructured pearlite structure. Ref. 11, Tabl. 3, Fig. 12. [ABSTRACT FROM AUTHOR] more...

Calculations for an ingot of 300 mm diameter of Ti-Al system intermetallic were conducted within the framework of the mathematical model of cylindrical ingots crystallization at electron beam melting. As a result of calculations, temperature fields in the ingot during electron beam melting were obtained, and technological modes of conducting the process were determined. The determined technological modes were used to produce a large-sized ingot of 300 mm diameter from Ti29Al alloy in electron beam installation UE-121. The quality of this ingot was studied and it was shown that application of optimized technological modes allows producing large-sized titanium aluminide ingots of homogeneous composition and without defects. Ref. 12, Table 1, Fig. 6. [ABSTRACT FROM AUTHOR] more...

Copyright of Electrometallurgy Today / Sovremennaya Elektrometallurgiya is the property of International Association Welding (Paton Publishing House) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

Copyright of Electrometallurgy Today / Sovremennaya Elektrometallurgiya is the property of International Association Welding (Paton Publishing House) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

Copyright of Electrometallurgy Today / Sovremennaya Elektrometallurgiya is the property of International Association Welding (Paton Publishing House) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

Copyright of Electrometallurgy Today / Sovremennaya Elektrometallurgiya is the property of International Association Welding (Paton Publishing House) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

Copyright of Electrometallurgy Today / Sovremennaya Elektrometallurgiya is the property of International Association Welding (Paton Publishing House) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...