VT6 Titanium Alloy Research Articles

Creep and long-term strength of hydrogen-containing VT6 titanium alloy with a piecewise constant dependence of tensile stress on time

Рассматривается ползучесть наводороженного стержня из титанового сплава ВТ6 при кусочно-постоянной зависимости напряжения от времени вплоть до разрушения. Обсуждаются результаты экспериментально-теоретического исследования влияния концентрации предварительно внедренного водорода на ползучесть и длительную прочность растягиваемых стержней из титанового сплава ВТ6 при температуре 600 $^\circ$C и постоянных номинальных растягивающих напряжениях в диапазоне от 47 до 217 МПа.

Surface saturation monitoring of forming products from titanium alloy VT20 with additives

In the publication, the saturation of the surface of a large size of stamped articles made of VT20 alloy with interstitial impurities and the formation of non-metallic compounds on it were investigated. The process of gas saturation in several directions depending on external parameters: heating temperature, medium, holding time is analyzed.

A Mesoscale Study of Fatigue Fracture of Near β Titanium Alloy VT22 after Radial Shear Rolling with Subsequent Aging

A Mesoscale Study of Fatigue Fracture of Near β Titanium Alloy VT22 after Radial Shear Rolling with Subsequent Aging

Microstructure and Phase Composition of VT1-0, VT6, and VT14 Titanium Alloys Produced by Wire-Feed Electron-Beam Additive Manufacturing

Microstructure and Phase Composition of VT1-0, VT6, and VT14 Titanium Alloys Produced by Wire-Feed Electron-Beam Additive Manufacturing

Experimental Study of Chip Shrinkage in Turning Titanium Alloy VT6

The article proposes an analysis of the study of turning a titanium-based alloy used for the manufacture of surgical implants. The main focus is on machinability problems associated with the choice of rational cutting parameters, which determine the quality and durability of pedicle screws. The conclusion is made about the need for research aimed at ensuring maximum performance and application of practical data for the manufacture of medical implants. To carry out experimental studies, non-free cutting of a titanium alloy bar was performed with a cutter fixed in a turning dynamometer. Graphs of cutting forces versus cutting speed and feed were used to select an effective combination of machining parameters. A thermal imaging camera was used to evaluate the effect of processing parameters on the temperature of the processed sample. Conclusions are drawn about the dependence of the coefficients of longitudinal and transverse chip shrinkage on the processing parameters. The results of the research analysis show that when turning titanium alloy VT6, the coefficient of transverse chip shrinkage, which characterizes the broadening with increasing cutting speed, remains unchanged. The goals of further research aimed at clarifying the optimal cutting conditions for turning transpedicular fixation screws from VT6 were determined.

Cutting Force during Face Milling of a Coarse- and Ultrafine-Grained VT6 Titanium Alloy

Cutting Force during Face Milling of a Coarse- and Ultrafine-Grained VT6 Titanium Alloy

Features of Deformation and Failure of Titanium Alloys Under Compressive Loads (On the Example of Titanium Alloy VT-6)

Features of Deformation and Failure of Titanium Alloys Under Compressive Loads (On the Example of Titanium Alloy VT-6)

Determining the structure and properties of heat-resistant titanium alloys VT3-1 and VT9 obtained by electron-beam melting

This paper reports a comprehensive study that investigated the quality of heat-resistant titanium alloys VT3-1 and VT9 obtained by the method of electron beam melting (EBM). It is shown that EBM makes it possible to produce high-quality metal of ingots of heat-resistant titanium alloys VT9 and VT3-1. Semi-finished articles were made in the form of bars from ingots obtained by the EBM method. It was established that in the macrostructure of the deformed metal there are no cracks, delamination, cavities, metal and non-metallic inclusions. The macrostructure of the metal of the bars corresponds to 4 points for the alloy VT3-1 and 4–5 points for the alloy VT9 on the 10-point scale of microstructures of instruction 1054-76. It was shown that the metal microstructure of forged bars of VT9 alloy consists of primary β grains with a continuous or intermittent α-rim along the grain boundaries 3–4 μs thick. The structure of the metal in the volume of grain – lamellar type with partially globularized plates of the α phase, plates of α-phase of close orientation form α colonies measuring 10–40 μs. The thickness of the α plates is 1–5 μs, between the plates or globules of the α phase there is a layer of β phase with a thickness of 1–2 μs. The microstructure of the deformed metal of titanium alloy VT3-1 consists of primary β grains, the volume of which contains colonies of lamellar α phases measuring 10–100 μs. The thickness of α plates is 1.5–3 μs, the layer of β phase in the intervals between α-plates is mainly 0.3–0.5 μs. The microstructure of semi-finished articles in the form of deformed bars of alloys VT9 and VT3-1 corresponds to type 4–6 according to the 9-type scale of the microstructure of instruction 1054-76. Studies of the mechanical properties of the obtained semi-finished articles have shown that they meet all the requirements of regulatory standards that are put forward by industry to the quality of the metal of heat-resistant titanium alloys

Оценка влияния износостойкого покрытия на процесс точения титанового сплава

The results of a study of the machinability of titanium alloy VT1-0 are presented. The influence of the wear-resistant coating of the cutting tool on the cutting forces is analyzed. It is shown that when turning with a cutting tool without a wear-resistant coating, the cutting forces and friction force are lower than when turning with a tool with a coating. Based on the applied Taguchi method, effective cutting conditions were selected, at which maximum productivity is achieved

EXPERIMENTAL STUDIES OF TEMPERATURE OF DIAMOND GRINDING OF HEAVYLY PROCESSED MATERIALS WITH SOLID LUBRICATION

The influence of hard lubrication on the processes of diamond grinding (DG) and diamond spark grinding (DSG) of hard-working materials - hard alloy VK6, titanium alloy VT22 and heat-resistant stainless steel 10H11N23T3MP was studied. The conditions of the performed experimental researches are described. The evaluation was performed according to the parameters of the surface roughness parameter Ra of the postcontact temperature Tpk. It was found that the use of solid lubricants (SL) based on stearic acid (65%) and molybdenum disulfide (35%) reduces 1.4… 2.1 times post-contact temperature and roughness 1.3… 1.6 times with diamond grinding of alloy VT22 and steel 10Х11Н23Т3МР. At DSG the character of influence of SL on Ra and Tpk does not change, but their absolute values increase in 1,1… 1,5 times.

Влияние технологических параметров на структуру металла изделий, полученных методом прямого лазерного выращивания из титанового порошка ВТ6

Direct laser deposition is an efficient approach to manufacturing or repairing a range of metal goods. The process involves creating a three-dimensional solid object layer by layer. The weld metal structure primarily affects mechanical properties of the deposited parts, making it important to establish the specifics of microstructure formation. We analysed the microstructure of VT6 alloy samples deposited on a substrate forged from the same VT6 titanium alloy. Different modes of deposition and subsequent heat treatment resulted in samples with differing structures. We established characteristic features of microstructure formation for all modes. We investigated the effect of heat treatment on the sample structure after laser welding in the initial state and after heat treatment. The results obtained may help reduce the cost of repairing and manufacturing titanium alloy parts for gas turbine engines.

Dependence of the Surface Hardening of VT22 Titanium Alloy on the Conditions of Nitriding Combined with Heat Treatment

Dependence of the Surface Hardening of VT22 Titanium Alloy on the Conditions of Nitriding Combined with Heat Treatment

Plastic Anisotropy Effect on Variation of Mechanical and Structural Properties of VT23 Titanium Alloy Subjected to Impact-Oscillatory Loading.

The main regularities in the impact of varying intensity impact-oscillatory loading on the variation of the mechanical and structural properties of the VT23 high-strength two-phase transverse-rolled sheet titanium alloy have been found. The intensity of the impulse introduction of energy into the alloy under the dynamic non-equilibrium process (DNP) was estimated by εimp (the increment of dynamic strain). The pulse intensity was found to change the shape of the static strain diagram with further tensioning, as compared to the initial state. This indicates the effect from the structure self-organization inherent in the VT23 titanium alloy upon the DNP. After the DNP (εimp = 1.44%), with further static deformation, the tensile diagram revealed yield sites up to 6.5% long. In most cases, the DNP was found to have a negative effect on the variation of the mechanical properties of the VT23 titanium alloy, especially if the latter was rolled in the transverse direction. The optimal DNP intensity is εimp~1.5%. In this case, the DNP can be used as an effective plasticization technology for the VT23 titanium alloy (regardless of the rolling direction) in the stamping of high-strength titanium alloys. Changes in the mechanical and structural condition of the VT23 titanium alloy subjected to the DNP were confirmed by the fractographic investigation of specimen fractures.

STUDY OF THE INFLUENCE OF THE KINETICS OF HYDROGEN SATURATION ON THE STRESS-DEFORMED STATE OF A SPHERICAL SHELL MADE FROM TITANIUM ALLOY

In this paper, a mathematical model is considered that allows one to determine the stress-strain state of a spherical shell made of titanium alloy VT1-0, the external load is assumed to be transverse uniformly distributed, acting on the outer surface, the medium is assumed to act on the inner surface of the shell. For this, a nonlinear model was used, presented in normalized stress spaces. Fastening along the contour of the shell is rigid. Nonlinear resolving equations for calculating a spherical shell are obtained. An algorithm for solving the problem of hydrogenation of titanium alloy shells has been developed. A practical solution was made by a two-step method of sequential perturbations of parameters using the MatLab and Maple software packages. To solve the system of the obtained differential equations, the method of finite differences is applied. The calculation of the stress-strain state of the shell is obtained taking into account the diffusion process of an aggressive hydrogen-containing medium, and the obtained solution is compared with the results of the classical nonlinear theory without taking into account the aggressive medium. The results of comparing these solutions demonstrate quantitative differences in the parameters of the shell deformation process, which are explained by a more accurate account of the influence of the type of stress state. This approach has a rather flexible mechanism for considering the initial and induced differential resistance, demonstrates a high accuracy of matching the obtained theoretical results with empirical data on loading a wide range of materials under complex types of stress state.

The effect of ion‑plasma nitriding on the enduring quality and the nature of changes in the surface roughness of titanium alloys VT1‑0, VT6 and OT4‑1

The effect of the temperature of the ion‑plasma nitriding process on the enduring quality of the resulting hardened layers on titanium VT1‑0 and titanium alloys VT6 and OT4‑1 and the effect of ion‑plasma nitriding on the change in the Ra parameter of the surface roughness of titanium samples is investigated. It is defined that ion‑plasma nitriding leads to a significant increase in the enduring quality of the titanium alloys under study. The depth of the enduring quality groove in untreated samples of titanium VT1‑0, alloys VT6, OT4‑1 was 11, 7 and 10 microns, respectively, whereas in samples after ion‑plasma nitriding, the wear groove had a depth of 1.9, 0.9, 2.1 microns. It was revealed that when the initial roughness of the processed samples is more than Ra 0.1 microns after ion nitriding, the roughness index Ra, one of the key components of surface quality, decreases.

Inspection of ratcheting models for pathological error sensitivity and overparametrization

Accurate analysis of plastic strain accumulation under stress-controlled cyclic loading is vital for numerous engineering applications. Typically, models of plastic ratcheting are calibrated against available experimental data. Since actual experiments are not exactly accurate, one should check the identification protocols for pathological dependencies on experimental errors. In this paper, a step-by-step algorithm is presented to estimate the sensitivities of identified material parameters. As a part of the sensitivity analysis method, a new mechanics-based metric in the space of material parameters is proposed especially for ratcheting-related applications. The sensitivity of material parameters to experimental errors is estimated, based on this metric. Moreover, a relation between pathological error sensitivity and overparametrization is established. This relation gives rise to a new criterion of overparametrization. The advantages of the new overparametrization criterion are exposed and its plausibility is checked by alternative criteria, like the consideration of correlation matrices and validation of identified parameters on “unseen” data. For demonstration purposes, the accumulation of irreversible strain in the titanium alloy VT6 (Russian analog of Ti-6Al-4V) is analysed. Three types of phenomenological models of plastic ratcheting are considered. They are the Armstrong-Frederick model as well as the first and the second Ohno-Wang models. Based on real data, a new rule of isotropic hardening is proposed for greater accuracy of simulation. The ability of the sensitivity analysis to determine reliable and unreliable parameters is demonstrated.

Structure and properties of electroslag welded joints of VT6 titanium alloy

The Paton Welding Journal, 2022, №05. International Scientific-Technical and Production Journal «The Paton Welding Journal» «The Paton Welding Journal» has been published monthly since 2000 in English, ISSN 0957-798X. «The Paton Welding Journal» is a cover-to-cover English translation of the «Avtomaticheskaya Svarka» (Automatic Welding) journal. The «Avtomaticheskaya Svarka» journal has been published monthly since 1948 in Russian, ISSN 005-111X.

Investigation of the properties of oxide coatings on titanium alloys obtained by plasma electrolytic oxidation

The use of structures made of titanium and its alloys, which have improved corrosion, physical and mechanical properties, are in demand in many industries. In this regard, the processes of modifying the surface of metals are of interest. One of the modern and promising methods of metal surface treatment is plasma electrolytic oxidation. Currently, there is a problem of widespread use of this process when DC modes are used in the implementation of the process. This is due to the large consumption of electricity. The purpose of this work is to study the morphological and corrosion properties of oxide coatings obtained in the pulsed anodecathode mode on titanium alloys VT1-0 and VT5 in various electrolyte solutions. Modification of the surface of titanium alloys was carried out at the duration of the anode current pulse of 250 ± 25 microseconds, the duration of the cathode current pulse of 5 ± 0.5 ms, the repetition frequency of the anode and cathode pulses of 50 ± 0.5 Hz. Alkaline solutions served as electrolytes. Oxide coatings obtained in various electrolytes are characterized by different porosity and coating thickness. Coatings with a finely porous structure, with an average pore diameter from 0.09 microns to 0.4 microns, and larger pore sizes of 0.6 – 0.7 microns were obtained. The porosity of the coatings ranges from 6.12% to 12.2%. According to the data of energy dispersion analysis, it was found that the structure of oxide coatings includes both components of the processed metal and components of the electrolyte solution. The main components, in this case, are oxygen and processed metal, as well as other elements such as boron, phosphorus, aluminium, fluorine, sodium, silicon and others. Corrosion tests according to GOST 9.308-85 under the influence of neutral salt mist at a temperature of (35 ± 2) °C with 1500 hours in the Ascott CC 450 chamber, it was shown that there was no corrosion damage to the coatings.

Use of non-thermal plasma for decontamination of titanium implants

Non-thermal plasma (NTP) has a non-specific bactericidal effect as a result of the synergistic activity of biologically active components contained in the plasma torch. As part of this work, we investigated the potential of using NTP for the antibacterial treatment of titanium implants. Applying samples made of the VT6 titanium alloy used to create implants and a strain of antibiotic-resistant staphylococcus MRSA, we showed that 1) plasma pretreatment of the sample surface led to the formation of a film containing titanium oxides which have a weak bactericidal effect reducing the colonization of the surface with staphylococcus; 2) direct plasma treatment of a polished titanium disk for 120 seconds reduced the contamination of S. aureus by 563 times; 3) the relief of the titanium surface itself plays an important role in the effectiveness of decontamination: the bacteria on the rough surface were less susceptible to the effects of NTP than the bacteria on the polished surface. In total, the data obtained indicate the need to continue research aimed at increasing the effectiveness of the bactericidal activity of NTP against bacteria on the surface of titanium implants.

Optimisation of the bore reaming process in hybrid stacks made of carbon fibre and metal alloys

The present work aims to improve the existing technology of reaming bores in hybrid stacks containing a composite material interlayered with titanium and aluminium alloys. The study was conducted using statistical approaches at the stages of experimental design and data processing in the Statistica 6 and Microsoft Excel 2010 software. The bore roughness was measured using a Taylor Hobson Form Talysurf i200 contact profilometer. The height of the tool build-up edge was investigated using a Bruker ContourGT-K1 optical profilometer. Bore diameters were determined using a Carl Zeiss Contura G2 coordinate measuring machine. An experimental study was carried out using an Atlas Copco PFD-1500 automatic feed drilling unit and a 14 mm MAPAL reamer with a replaceable head. A methodology for a comprehensive experimental study of boring and reaming processes in the “OT4 titanium alloy - VT6 titanium alloy - polymeric composite materials - VT6 titanium alloy - 1933 aluminium alloy” hybrid stack was developed and implemented. It was found that the most significant factors affecting the parameters of bore accuracy, in particular, the deviation from the true bore longitudinal section profile, include the cutting speed in the first and the second degree, as well as the feed. The optimum cutting modes are a cutting speed of 7.24 m/min, a feed of 0.27 mm/rev and a machining allowance of 0.5 mm. As a result, the time of reaming one bore is reduced by 4.6 times. The optimum cooling method, ensuring the increased accuracy and reduced roughness of the bore in the aluminium alloy layer, is cooling by carbon dioxide at a temperature of -56.5°C. As a result of experimental works, basic laws governing the boring and reaming processes in multicomponent hybrid stacks composed by carbon-fibre-reinforced plastics with titanium and aluminium alloys were investigated.