Production Of Titanium Alloys Research Articles

Electrochemical characteristic and microstructure of Ti-6Al-7Nb alloy by centrifugal casting for orthopedic implant based on ageing time variations

Electrochemical characteristic and microstructure of Ti-6Al-7Nb alloy by centrifugal casting for orthopedic implant based on ageing time variations

A Combined Experimental and Numerical Calibration Approach for Modeling the Performance of Aerospace-Grade Titanium Alloy Products

Finite element modeling for designing and optimizing lightweight titanium aerospace components requires advanced simulation tools with adequate material modeling. In this sense, a hybrid strategy is proposed in this work to identify the parameters of the Johnson–Cook plasticity and damage laws using a combined direct-inverse method. A direct calibration method for plasticity law is applied based on the literature-reported data of strain-stress curves from experimental tensile tests at different temperatures and strain rates. The triaxiliaty-dependent fracture parameters of the Johnson–Cook damage law at reference conditions of strain rate and temperature (d1, d2, and d3) are calibrated with the direct method based on new data of experimental evolution of computed average fracture strain with the average stress triaxiality. The validation is performed with numerical results from an accurate micromechanics-based Ti64 model. The inverse calibration method is used to determine the strain rate and temperature-dependent damage parameters (d4 and d5) through large strain simulations of uniaxial tensile tests. The numerical results, including average strain and necking profile at fracture, are then utilized to calculate stress triaxiality by the Bridgman criterion for adjusting parameters d4 and d5. The calibrated model yields a 2.1% error for plasticity and 3.4% for fracture predictions. The experimental and simulated load-bearing capacity using the micromechanics damage model differed by only 1%. This demonstrates that the SC11–TNT model of Ti64 is reliable for identifying the Johnson–Cook damage law through the accurate use of inverse methods. The hybrid calibration strategy demonstrates the potential capability of the identified Johnson–Cook model to accurately predict the design load-carrying capacity of Ti64 aerospace components under different deformation rates and temperatures while accounting for material damage effects.

Research Progress of Preparing Titanium Alloy By Molten Salt Method

Titanium alloy has excellent characteristics that cannot be compared with other metals such as light specific gravity, high specific strength, wide applicable temperature range, corrosion resistance, and hydrogen storage. The traditional titanium alloy smelting process is mainly based on titanium sponge as raw material, which has a long process, high energy consumption, heavy pollution, and other problems, which seriously restricts the sustainable development of titanium alloy in the world. The common methods of preparing titanium alloy are alloy melting, metal thermal reduction, powder metallurgy, and the gradually emerging molten salt electrolysis. Among them, molten salt electrolysis is recognized as the most promising method to replace the traditional titanium alloy production process, and certain achievements have been made in recent years in terms of both process and basic theory research. In this paper, the common processes of titanium alloy preparation by molten salt electrolysis at home and abroad, such as molten salt electrolytic co-deposition method, cathodic alloying method and liquid cathode method, new FFC method, and its derived SOM method, etc., will be summarized systematically, and the future research will be put forward.

Demin K.A. Role of pulsed electron beam treatment in forming of operational properties of working surfaces of biomedical titanium alloy products

The article presents the study of the effect of pulsed electron beam treatment on the surface roughness of samples made of titanium alloy VT-6, obtained by two methods: mechanical processing and additive manufacturing. It has been established that electron beam treatment allows reducing the roughness of titanium alloys in both cases, which can be extremely important for polishing small-sized products, particularly those with low mechanical strength or unique microrelief surface.

Experimental Analysis of Fatigue Crack Path for Strained Functionally Graded Materials

This paper experimentally discusses crack paths in strained Functionally graded materials under constant loading conditions and vibration fatigue. The objective is to synthesize the body of knowledge on the stability of FGM. The article presents the development, production, and characterization of multi-Al (aluminum), Ni (nickel), and Titanium alloys. FGM it was successfully modified using the powder metallurgical technique. Five-layer FGM samples frequently utilize (Al, Ni), on one end and (Al-Ni-Ti) on the first. FGM sample mechanical characteristics have been investigated using wear and Fatigue testing. The Al/Ni/Titanium FGM compact specimen approaches the yield stress and ultimate stress values, which is regarded as a significant improvement in mechanical qualities with less weight. The test findings are for a constant amplitude load fully reversed with zero mean stress. The stress life approach examined three samples' fatigue characteristics and natural frequency under random vibration.

Hydrogen sintering, microstructure, and mechanical properties of Ti-10V-2Fe-3Al alloys prepared by the blended elemental method

This investigation utilized an economical hydrogen sintering technique to fabricate the Ti-10 V-2Fe-3Al aerospace alloy. We examined the phase and microstructural evolution throughout the densification, hydrogen sintering, and dehydrogenation processes. Hydrogen dissolution prompted titanium deformation, culminating in an ultrafine-grained microstructure reinforced with α-phases. Notably, the hydrogen-sintered alloy showcased a microstructure comparable to that of forged alloys, diverging from traditional sintering approaches. Enhanced tensile and yield strengths were also documented. Collectively, hydrogen sintering presents a viable avenue for augmenting the microstructures and mechanical attributes of economically efficient titanium alloy products.

Effects of HIP Process Parameters on Microstructure and Mechanical Properties of Ti-6Al-4V Fabricated by SLM

Ti-6Al-4V titanium alloy products formed by selective laser melting (SLM) are characterized by high strength and low plasticity. In addition, there may be pores inside the material, which may become a fracture sprouting point and accelerate the failure of the parts. Using an optical microscope (OM), scanning electron microscope (SEM), and electronic universal testing machine, the effects of hot isostatic pressing (HIP) parameters on the microstructure and tensile property of SLM-formed Ti-6Al-4V titanium alloy were investigated. The results show that HIP performed below the β-phase transition temperature, and the structure of the Ti-6Al-4V titanium alloy is composed of an α phase and β phase. With the increase in the HIP temperature, the α lath coarsens into a short rod, the content of the β phase increases and coarsens, and the tensile strength and yield strength of Ti-6Al-4V show a decreasing trend. With an HIP process performed at a temperature of 910 °C and pressure of 130 MPa for 2 h, the Ti-6Al-4V titanium alloy obtains the best matching of strength and plasticity.

Study on fabrication of metallic Titanium from secondary Titanium slag of Binh Dinh titanium minerals using magnesiothermic reduction method

Titanium and its alloys are used in aviation, marine, medical, chemical and other fields because of their superior properties, such as low density, good corrosion resistance, high strength and biocompatibility. This paper presented a study on the possibility of producing metal titanium from secondary titanium slag by magnesiothermic reduction. The prepared products were characterized using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and electron microscopy (SEM). The research results show that the magnesiothermic reduction method is capable of producing Ti metal directly from the secondary titanium slag with high recovery efficient. The resulting product is high-purity porous titanium, with a titanium content of up to 94,68% (without unfavourable impurities). The properties of Ti meet the requirements for the production of high-quality titanium alloys.

ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ОДЕРЖАННЯ СПЛАВІВ ТА ЛІГАТУР СИСТЕМИ TI–ZR–NB–SN В УМОВАХ ЕЛЕКТРОННО-ПРОМЕНЕВОЇ ЛИВАРНОЇ ТЕХНОЛОГІЇ

Electron beam casting technology is a unique method for obtaining cast products and semi-finished products from a wide range of titanium alloys. This technology can be very promissing in production of biocompatible titanium alloys for endoprosthesis. A particularly difficult and important task in this context is preparation of Ti-Zr-Nb-Sn system alloys with high strength and low modulus of elasticity. As a result of experimental development of specified alloys melt preparation technological modes, possibility of obtaining complex titanium alloys with a high content of zirconium and niobium was shown. It is also determined, that when the niobium content in the charge is more than 30 % wt. there is a decrease in the concentration of titanium and zirconium in the melt due to their freezing on the walls of the skull. As a result, there is a change in the chemical composition of the melt, the amount of niobium in which can exceed 50 % wt. Maximum amount of tin that can be assimilated in titanium-based melts under EBCT conditions is 5 % wt., and niobium-based melts are twice less. It has been proven that obtaining melts of Ti-Zr-Nb-Sn system with a precise chemical composition, using the chosen method, is a difficult and still unsolved problem, but due to the possibility of melting alloys with a high content of niobium and zirconium in its conditions, this method is effective in the production of master alloys and ingots for the production of powders used as raw materials for additive tmanufacturing. Keywords: titanium alloys for endoprosthesis, foundry production, Ti-Zr-Nb-Sn, electron-beam casting technology.

One-step production of high-strength titanium alloy by sintering titanium hydride powder from upgraded titania slag

A direct production method of high-strength titanium alloy from upgraded titania slag (UGS) was developed. First, UGS was reduced into alloy powder with 1.3 wt.% oxygen using magnesium powder. Subsequently, the alloy powder was compacted at 600 MPa to produce a pellet. Lastly, the pellet was sintered to produce titanium alloy. The reduced powder was characterized, and the effect arising from the sintering temperature on the sintered density, compressive strength, microstructure, and hardness of the alloys was studied. The results showed that the density tended to increase with the temperature increasing from 900 to 1200 °C, whereas the porosity decreased. A significant sintering densification was achieved at the temperature above 1100 °C (98.65% at 1100 °C and 99.41% at 1200 °C). At 1100 °C, the hardness and compressive strength reached the maximal values of the alloy, HV 655.7 and 1563 MPa, respectively.

Optimization of Multi-Track Laser-Cladding Process of Titanium Alloy Based on RSM and NSGA-II Algorithm

Titanium alloy is an important material in the 21st century and its consumption in the aerospace and energy fields is increasing. In the production and repair of titanium alloy, the problem of energy saving and consumption reduction is becoming increasingly important. Laser-cladding technology with optimized parameters can bring great economic benefit. In order to obtain the best process parameters of laser-cladding TC4 alloy powder, a method of laser-cladding parameters’ optimization based on the RSM and NSGA-II Algorithm is proposed. The BBD (Box–Behnken Design) experiment scheme was designed by the response surface method. A surrogate model between input variables (laser power, scanning speed, and powder-feeding speed) and response values (macroscopic quality, microhardness, and average friction coefficient) was established. The second generation non-dominant sorting genetic algorithm (NSGA-II) was used to optimize the process parameters and the optimization results were verified by experiments. The results show that the optimum parameters are a laser power of 2600 W, scanning speed of 19.1 mm/s, and powder-feeding rate of 12.2 g/min. The samples prepared with the best process parameters show mainly abrasive wear, accompanied by a small amount of adhesive wear. Its wear depth is 7.71 μm and the average friction coefficient is 0.293. After cladding, the macroscopic quality of the cladding layer is increased by 5.8%, the microhardness is increased by 10.1%, and the average friction coefficient is reduced by 27.6%.

Effect of fibre laser welding parameters on the microstructure and weld geometry of commercially pure titanium

The primary purpose of the study was the metallurgical characterization of laser welds. The weldability of commercial production of pure titanium and titanium alloy (CP-Ti) has also been examined. In this research, the laser fibre method was used to weld sheets of pure titanium, and then microscopy and scanning electron microscopy were used to study the changes in the microstructure, the depth of weld penetration and the width of the weld area with changing welding parameters. The results proved that increasing the laser power significantly increases the depth of weld penetration and weld width. When the heat input is increased, the shape of the weld pool changes from a V shape to an hourglass shape. It was also observed that the depth of the crater formed increases with the increase in the laser power due to the increase in the melting and evaporation of the weld metal. Increasing the welding speed also has a negative impact on the weld geometry because it reduces the heat input and absorption of laser energy by the weld metal and thus reduces the melting of the metal. The microstructure of the fusion zone consists of acicular α. Fine grains formed in the weld centre at low heat input; the granules became columnar-like. Since commercially pure titanium contains a small amount of beta-phase stabilizers, the cooling rate is extremely high for martensite to occur. In the future, it is recommended to study the effect of changing welding parameters on the mechanical properties of pure titanium because of its great importance in industrial and medical applications. Studying the effect of changing laser power and welding speed on the metallurgical properties of pure titanium, and consequently its effect on the mechanical properties of welds.

Green Forging of Titanium and Titanium Alloys by Using the Carbon Supersaturated SKD11 Dies

The carbon-supersaturated SKD11 punch was proposed as a green, or, a galling-free, long-life and low energy-consuming forging tool of pure titanium and β-titanium alloy that works with low friction and less work hardening and without galling. The reduction in thickness was increased up to 50% to investigate the friction process on the contact interface and the work-hardening behavior. The nitrogen-supersaturated SKD11 punch was utilized as a reference tool for this forging experiment. Three-dimensional finite element analysis was employed to derive the regression curve between the contact interface width and the friction coefficient. The friction coefficient was estimated in forging the pure titanium wires by using the regression curves. The work-hardening process was analyzed by the hardness mapping on the cross-section of forged wires. The SEM-EDX analysis on the contact interface proved that no adhesion of fresh metallic titanium and titanium oxide debris was seen on the interface between the carbon-supersaturated SKD11 punch and the titanium work. In particular, the work hardening is suppressed without shear localization in forging the β-titanium. Finally, the uniform carbon layer was derived from the supersaturated carbon solute from the punch matrix and wrought as a friction film on the contact interface to reduce the friction and the work hardening as well as suppress the chemical galling. This in situ carbon lubrication must be essential in green forging to highly qualify the titanium and titanium alloy products and to prolong the punch-and-die lives in practical operation.

Production and characterization of titanium based metal matrix composites: a review

Titanium alloys are regarded as high strength and lowdensity alloys. It has wide range of applications such as in biomedical and automobile because of its high strength, low density, biocompatibility and good corrosion resistance. Titanium alloys can be produced by adding elements like aluminium, vanadium, molybdenum, zirconium etc. The powder metallurgy method is widely used method for production of titanium alloys because of its low cost of production. In this study, Ti6Al4V based composites synthesized by adding various reinforcements through powder metallurgy method are considered and the results from these studies are reported.

Research status and prospect of ceramic crucibles for induction melting of titanium alloys

<p indent="0mm">Titanium alloys possess high specific strength, superior heat resistance, excellent corrosion resistance, outstanding physiological compatibility, etc., and thus being considered as the most ideal lightweight structural materials as well as potent biomedical materials. Generally, Ti alloys are manufactured via the technique of ingot metallurgy; however, it suffers from critical issues of high energy consumption and high cost, which desperately need to be well addressed. According to previous research, the crucible vacuum induction melting technology has high superheat and strong electromagnetic stirring, with which titanium alloy ingots with uniform composition can be achieved without applying multiple remelting. The crucible vacuum induction melting not only benefits the removal of low melting point impurities, but also significantly improves the energy consumption efficiency as the forced water cooling becomes not indispensable during the processing. As a result, the crucible vacuum induction melting has been the most potential method to overcome the problems of high energy consumption and low material yield existed in conventional melting technology. However, titanium alloys can react with almost all the refractories because of their high chemical activity, resulting in the pollution of titanium ingot and thus seriously restricting the development and application of this technology in titanium alloy production. For this reason, preparation special crucibles with corrosion resistance to titanium liquid is crucial to realizing low-cost, high-quality, and high-efficiency smelting of titanium alloys. Herein, we provide a comprehensive review of the research status of ceramic crucibles for titanium alloys including the selection of materials (thermodynamic criterion, corrosion resistance mechanism, composition optimization) and the promising processes to improve the durability of these crucibles. Usually, the thermodynamic criterion is used as the first-step to pick ceramic materials with high chemical stability, which involves a comparison of the free energies of formation of ceramic materials with their corresponding titanium compounds. It is necessary to further evaluate the interface reaction mechanism between candidate ceramic materials and titanium melts under induction melting conditions to compensate for the neglect of disregarding physical and chemical erosion in thermodynamic approach. Based on a systematically comparison of the interface reaction mechanism between titanium melts and various common refractory materials involving oxide ceramics (Y₂O₃ and CaO), zirconate ceramics (BaZrO₃ and (Ca,Sr,Ba)ZrO₃) and non-oxide ceramics, AlN and TiN show promising properties for melting titanium alloys due to their relatively smaller oxygen contamination. In addition to corrosion resistance of ceramics against titanium melts, the thermal shock resistance is the other critical criterion to realize a long service life of the crucibles under repeated induction melting conditions. Scholars attempted many methods, such as porosity optimization, doping modification, surface coating, to solve the imbalance between the corrosion resistance of titanium liquid and thermal shock resistance of materials. Currently, the crucibles can only be prepared at laboratory size, how to realize the production of large-size crucibles with balancing the cost, corrosion resistance and thermal shock resistance is full of serious challenges. On the basis of the recent research progress of Huazhong University of Science and Technology, innovative thinking in terms of the future development of ceramic crucibles for titanium alloy induction melting is suggested: (1) the optimization of refractories: how to reap the advantages of computer technology to speed up the development of new crucible materials; (2) higher demands for thermal shock resistance and high temperature strength: figuring out the relationship between the preparation parameters and the surface quality of the crucibles; (3) the preparation of the special crucibles with large size, high durability: addition of ultra-high temperature reinforcements being a promising route for the fabrication of industrial grade crucibles for titanium alloys induction melting.

Corrosion resistance of calcium zirconate crucible to titanium-copper melts

The corrosion resistance of refractory materials to the titanium alloy melts is vital for the production of titanium alloys by vacuum induction melting. In this study, the corrosion behavior of calcia-stabilized zirconia, solid state synthesized calcium zirconate, and fused calcium zirconate refractory suffering Ti-5 wt% Cu melts were investigated at 1680 ℃ for 15 min of soaking time by the cup test method. It was found that the three crucibles directly dissolved into the titanium melt, then generated Ti (Zr, O) and CaZrO3 in the infiltration layer, and eventually developed a porous Ti3O layer in the lining. Besides, the contamination of Ti-5 wt% Cu alloy (oxygen: 5.3 wt%; zirconium: 6.01 wt%; calcium: 0.42 wt%) by fused calcium zirconate crucible was significantly less than the solid state synthesized one (oxygen: 5.83 wt%; zirconium: 6.14 wt%; calcium: 0.43 wt%), implying that the production method of calcium zirconate notably affected the impurity of titanium alloys.

Cold Spray Additive Manufacturing of Ti6Al4V: Special Nozzle Design Using Numerical Simulation and Experimental Validation

Cold spray additive manufacturing (CSAM) shows great potential in titanium-alloy production as it is a solid-state process. However, data published so far have demonstrated the difficulty of producing dense and high-strength Ti alloy parts. Our previous studies have shown that nozzle design together with high-cost helium propulsive gas plays a crucial role in particle acceleration. In this work, special nozzles for Ti alloy were designed and validated experimentally with commercially available Ti6Al4V powder. Simulation results show that particle impact temperature increases remarkably for a long convergent length, while particle kinetic energy slightly increases, which is validated by experiments. The relationship between the particle impact temperature and practice diameter shows the first increase and then decrease. The experimental results show that as the nozzle convergent section becomes longer, the edges of the single-pass deposits become smoother, and the width, density, deposition efficiency, and microhardness of the single-pass deposits increase.

Numerical Simulation of the Effects of Scanning Strategies on the Aluminum Evaporation of Titanium Alloy in the Electron Beam Cold Hearth Melting Process.

In the production of titanium alloy, the electron beam cold hearth melting (EBCHM) process is commonly used due to its effectiveness and the high quality of the end product. However, its main drawback is the significant loss of elements such as aluminum (Al) due to evaporation under the vacuum environment. Numerical coupled thermal-flow models were here developed to investigate the effects of scanning strategies on Al loss in a titanium alloy during EBCHM. The validation model was successful in comparison with previously published experimental data. The Al mass fraction results at the outlet of the water-cooled hearth were strongly influenced by changes in the applied scanning strategies. The results indicated that the Al mass fraction loss could be reduced by using the full-hearth scanning strategies.

Features of formation somatic pathologies under chronic exposure to hydrofluoride in the manufacture of titanic alloys

Introduction. Most studies on the morbidity of workers with fluorine compounds are devoted to occupational medicine at aluminium industry enterprises. The aim of the study is to identify the exposure, gender and evolutionary features of the formation of general somatic morbidity associated with chronic occupational exposure to hydrofluoride in the production of titanium alloys. Materials and methods. The analysis of the prevalence of chronic pathology according to the medical examination of 562 workers in contact with hydrofluoride and the incidence of temporary disability according to 29949 disability sheets in comparison with non-exposed persons of the same enterprise is given. Results. With an increase in the degree of harmfulness of working conditions, there was an augmentation increase in the risk of developing pathology of the respiratory organs, eyes, musculoskeletal system, arterial hypertension and hypercholesterolemia. In the working conditions of Class 3.1, an increased prevalence of diseases of the nervous and genitourinary systems with a moderate degree of occupational conditionality was revealed (relative risks (RR) 1.6 and 2.0, respectively, р &lt; 0.05), class 3.2 - a high degree of professional conditionality of respiratory diseases (RR = 2.8). When working in harmful working conditions, there was an average degree of occupational conditionality of nervous system diseases in women (RR = 1.9) and a small degree of arterial hypertension in men (RR = 1.2). The prevalence of general somatic pathology in all age groups was higher than in non-exposed persons of the same age. Conclusion. Hydrofluoride in the production of titanium alloys was proved to be a trigger contributing to the formation of the pathology of the respiratory, circulatory, digestive, ear, eyes, skin, blood, musculoskeletal, nervous, endocrine, and genitourinary systems.

Influence law and optimization analysis of technological parameters of TC4 titanium alloy on water cavitation peening

TC4 titanium alloy is widely used in aerospace, petrochemical, pharmaceutical and other fields, which accounts for about 60% of the current titanium alloy products. Water Cavitation Peening (WCP) is a new material surface modification process and has great development potential. The improvement of the water cavitation peening is severely limited by the correlation and coupling between process parameters. Therefore, the influence law of each process parameter is the key problem that needs to be resolved. TC4 titanium alloy as research object is took and four main process parameters of WCP under four working conditions is construct (four factors and four levels orthogonal). The influence of process parameters on three evaluation indexes is studied, such as the surface residual stress, the surface roughness and the microhardness. Then, the fuzzy mathematics comprehensive evaluation is used to optimize. Results show that the peening time has the greatest influence on strengthening effect and the nozzle diameter has the least. The optimized combination is that the nozzle diameter is 1.4 mm, the incident pressure is 40 MPa, the dimensionless target distance is 72.5 and peening time is 27.5 min. The corresponding surface residual stress, the surface roughness and the microhardness can reach −612 MPa, 0.76 μm, and 405 HV respectively.