Production Of Titanium Alloys Research Articles

Finite element modeling of superplastic forming of ideal and intentionally defected titanium alloy products for the purpose of non‐destructive control

The work is devoted to the development of the production of three‐layered hollows structures made of VT6 titanium alloy by means of superplastic forming (SPF). Based on the numerical results the pressure cycle was determined to satisfy the superplastic flow condition in the stiffening ribs and to minimize the forming time.

Aluminothermic Production of Titanium alloys (part 1): Synthesis of TiO2 as input material

This article reports on the hydrometallurgical production of synthetic anatase from ilmenite. Mechanical activation followed by pressure leaching facilitates the leaching of ilmenite and the separation of titanium/iron by means of the synchronous hydrolysis of anatase. At 95% TiO2, the produced synthetic anatase fulfills the requirements for the aluminothermic production of titanium alloys.

Wear Resistance of Ti-40Zr Alloy with TiN and ZrN Multilayer Coatings

Production and processing of titanium alloys are expensive and its alloys show low wear resistance. Substrates of Ti-40Zr, used for orthopedic implants, were obtained from the elemental mixture of hydrogenated powders, followed by a sequence of cold uniaxial and isostatic pressing and vacuum sintering. Aiming wear resistance increase, samples were coated by physical vapor deposition using electron beam technique (EB-PVD). Multilayer coatings with three different configurations were undertaken: Ti/TiN, Ti/TiN/ZrN and Ti/TiN/ZrN/TiN. Micro-abrasive wear tests were conducted by ball-cratering, with abrasive slurry of silicon carbide (SiC). The wear craters were measured at intervals corresponding to increments in the sliding distance of approximately 14 m. Range of the normal force were between 0.35 and 0,45 N. Scanning electron microscopy was used to evaluate the wear crater and the wear mode. All experiments showed three-body abrasive wear and a reduction of one order of magnitude in wear coefficient for two coated samples: 2,58∙10-12m³(Nm)-1to substrate, 5,4∙10-13m³(Nm)-1to Ti+TiN film and 7,22∙10-13m³(Nm)-1to Ti+TiN+ZrN film. In the Ti+TiN+ZrN+TiN experiment the wear coefficient of film is nearer to the substrate, 7,58∙10-13m³(Nm)-1. The multi-layers containing ZrN presented wear coefficient higher than Ti/TiN films, possibly due to existing residual stresses.

Study of the properties of low-cost powder metallurgy titanium alloys by 430 stainless steel addition

Titanium is a lightweight metal with an outstanding combination of properties which make it the material of choice for many different applications. Nonetheless, its employment at industrial level is not widespread due to higher production costs with respect to competitor metals like steel and aluminium. In this work the production of low-cost titanium alloys is attempted by combining the utilisation of a powder metallurgy process and cheap alloying elements (i.e. commercial 430 stainless steel powder optimised for the powder metallurgy industry). Low-cost titanium alloys are fabricated by blending elemental titanium with stainless steel. The behaviour of the powders as well as that of the sintered materials are analysed and compared to that of a master alloy addition Ti6Al4V alloy. The produced low-cost titanium alloys show comparable properties to both wrought and powder metallurgy titanium alloys and, therefore, they are proposed as an alternative to obtain structural component made out of titanium alloys.

Investigation into the state of metal during radial-shear rolling on a SRVP-130 mill

Radial-shear rolling (RSR) plays an important role in the production of titanium alloys in OAO VSMPO-AVISMA (Verkhn. Salda), having a number of advantages over other processes of metal formation. A software complex for modeling formation and heat transfer in the metal volume has been developed during this investigation on the basis of engineering computation techniques, and the rolling of a bar of the VT6 alloy with a diameter of 155 mm has been studied using it. The ThemoRSR program, making it possible to image computational data in the Mathcad environment, is developed; rolling is modeled with a DEFORM-3D package; and conditions of its application are shown. Promising methods for measuring the rolling temperature and the torsion torque on a mill spindle are considered.

Role of Surface Contamination in Titanium PM

The powder metallurgy (PM) approach is widely used for cost-effective production of titanium alloys and articles. In the PM approach the large specific surface of starting powders heightens the risk of excessive impurity presence and, hence, degradation of final alloy properties. The present study analyzes the opportunity to produce sintered commercially pure titanium (CP-Ti) with acceptable impurity content from powder materials. Starting titanium and titanium hydride powders were comparatively examined. The impurity elements (oxygen, chlorine, carbon) and their conditions on the powder particle surface, as well as the surface processes and gases emitted from powders upon heating, have been analyzed by means of surface science techniques. The role of hydrogen emitted from titanium hydride in material purification has been discussed. The opportunity to produce titanium materials with final admissible content of interstitials (O, C, Cl, and H) using starting titanium hydride powder has been demonstrated.

Effect of Energy Density of Incident Beam on Mechanical Property of Titanium Alloy Products Fabricated by Electron Beam Melting (EBM) Method

Electron beam melting (EBM) is a promising fabrication technique for directly producing metal products from powder as the starting material. Powders are provided as a thin layer (~100 μm) and melted layer by layer with an electron beam. In this study, the effects of the energy density of the incident beam on the mechanical properties of Ti–6 mass% Al–4 mass% V alloy products fabricated through EBM were examined. The products were fabricated using an electron beam at various energy densities depending on the electron beam current. The microstructures and crystallographic orientations were observed using optical microscopy and electron backscatter diffraction (EBSD), respectively. Compression tests were carried out in 2 loading directions using a mechanical testing machine equipped with strain gauges, one perpendicular (x–y direction) and the other parallel (z direction) to the stacking direction. In principle, the microstructure consisted of an acicular-shaped α phase (hcp lattice) and a small-volume β phase (bcc lattice). In addition, columnar grains elongated toward the z direction appeared during the repeated melting and solidification that occurred during the EBM process. An increase in the beam current of the incident beam enlarged the α grains and increased the relative density, resulting in the related Young’s modulus of the products. The energy density caused by the beam current also introduces anisotropy in the deformation behavior depending on the loading axis toward the stacking direction. This is closely related to the cast defect arranged along the stacking layers. It was concluded that the mechanical properties of the Ti–6 mass% Al–4 mass% V alloy products formed through EBM were very sensitive to the incident beam current and stacking direction, resulting in the exhibition of anisotropic deformation behavior within a limited range of energy density.

Finite Element Analysis of TA15 Titanium Alloy Beam Hammer Forging Forming at Different Temperatures

The hammer forging forming process of TA15 titanium alloy girder is taken as an example on this study. When girder were formed at different original temperature as 850 °C、900 °Cand 950 °C, the needed hammering times and each hammer’s stroke and varieties of damage factor were researched respectively based on software Deform. By simulation analysis, the needed hammering times is 7 times, 5 times and 4 times in order, and the damage factor which dangerous place located at the right top fillet of girder reached the highest point at about 86mm stroke ,and the original temperature 950 °C gave the best answer. The results are significant theoretical foundation for the practical production and study of TA15 titanium alloy.

Investigation of the Milling Performance about Titanium Alloy Based on Orthogonal Experiment

The milling process has been widely used for manufacturing aeronautical materials. It is very important to choose the reasonable milling parameters for improving the machining accuracy and surface quality. In this paper, the orthogonal experiments are made to construct the relationships between the milling force and milling parameters to TA15 titanium alloy. And the milling parameters mainly include milling speed, milling depth, milling width and feed engagement. And the empirical equations of milling force are gotten by regression analysis, and the equations are tested to be correct by the single factor experiment. The result is quite important for further research on the milling performance and can serve as a reference to production of titanium alloys.

Titanium alloy production technology, market prospects and industry development

Titanium alloy with a low density, high specific strength, corrosion resistance and good process performance, is the ideal structural materials for the aerospace engineering. Based on the microstructure of titanium alloys, it can be divided into α-type titanium alloys (heat-resistant titanium alloys), β-type titanium alloys and α + β-type titanium alloys. The research scopes also include the fabrication technology of titanium alloys, powder metallurgy, rapid solidification technology, and other military and civilian applications of titanium alloys. Titanium and its alloys have become the ideal structural materials used for the fuselage, and accounted for a significant part of the structural quality in most military aircrafts. Titanium’s future market expectations need to be considered in the macro level market. Apart from the supply and demand trends of titanium market, it is necessary to consider the impact of technological innovations that can help to reduce the cost of titanium production.

대형 티타늄 합금 용기의 고온 금형 성형 공정 개발

In order to successfully implement hot die forging process for the large-size titanium alloy products, it is necessary to devise a customized heating method for the billets and the die tools, as well as the die tool design. This study aims at establishing a hot die forging process of the large-size titanium alloy container products by applying the warm die, semi-hot die and hot die forging process step-wise. To accomplish this purpose, forging mechanism and the die tools were designed considering the strength of die materials at the given die heating temperature. The movable heating devices for the billet and the die tools were also introduced to prevent overcooling of billet and die tools. To verify the applicability of the designed forging process, real-size forging tests were carried out and the quality of forged products, including dimension, surface condition, microstructure and the mechanical properties was evaluated.

Nanotechnologies for the formation of medical implants based on titanium alloys with bioactive coatings

The main approaches to the formation of modern functional materials for medical implants, including the principles of material choice on the criteria of their biochemical and biomechanical compatibility and their technological effectiveness, are represented in this review. Titanium alloys are considered the most prospective and extended materials for implants in traumatology, orthopedics, and stomatology. The trend over the last decade has been to exclude alloying components that may cause local allergic reactions on living tissues or general toxic effects on an organism from the structure of titanium alloys. One compromise to preserve high biochemical compatibility with the necessary increase in the mechanical properties of titanium alloys is based on the formation of submicrocrystalline (SMC) or nanostructured (NS) states in commercially pure titanium. The prospect of using SMC and NS titanium as a material for manufacturing implants is proven. An analysis of the results of experimental and theoretical research of the diffusion features on intergranular areas is carried out, and the role of diffusion-controlled processes in the formation of a microstructure of metals and alloys, as well as the microstructured state, is discussed. The efficiency of computer simulation on an atomic level in establishing the dependence of diffusion characteristics on intergranular areas from the average grain size and the structural state of internal boundaries of section is proven. A short description of simulation and semi-industrial methods of the formation of SMC and NS states in metals and alloys by means of severe plastic deformation—which are known as materials related to the “top-down approach,” assuming the initial structure is crushed to nanosized components—is presented. Special attention is given to the recent developed of low-cost and high-efficiency technological schemes for the mass production of nanostructured titanium alloys for medical purposes, including radial-shift and screw rollings, along with a combination of traditional methods of mechanical-thermal processing, which make it possible to receive an assortment of the titanium and its alloys necessary for the mass production of medical implants and tools.

Evaluation of Low Cost Titanium Alloy Products

Titanium has extremely attractive properties for air vehicles ranging from excellent corrosion resistance to good compatibility with graphite reinforced composites and very good damage tolerance characteristics. At current Buy to Fly ratios, the F-35 Program will consume as much as seven million pounds of titanium a year at rate production. This figure is nearly double that of the F-22 Program, which has a much higher titanium content. Lockheed Martin has initiated “Project Black Ti” to reduce the cost of titanium parts by reducing the titanium consumption but not the quantity of titanium parts. Ultimately, we want to reduce the inherent waste in the current processing of titanium alloy products. The Kroll process, by which most titanium product is made today, is nearly 60 years old. Kroll himself predicted the process would be replaced within 15 years due to inherent inefficiencies – in 1950. Titanium is also mis-characterized as a precious metal, which it is not. It is the ninth most abundant element on the earth’s surface. Aluminum by comparison is the third most abundant but has a much more efficient method to convert it to a usable form. Until the turn of the 20th century, aluminum was considered to be as precious as platinum until the Bayer Process brought prices down from $1200/kg to $0.60/kg. Regarding titanium, one way to improve efficiency and buy less material to make the same parts is via Powder Metallurgy (PM). Until recently, titanium alloy powder was very expensive. However, new methods of producing titanium alloy have been developed which generate powder as an output versus massive ingots, which require multiple melts to achieve homogeneity. With powder, in theory, we should be able to get much closer to net shape and reduce the initial buy and reduce significant machining costs. These low cost titanium powders are becoming commercially available, which has the potential to initiate a paradigm shift in the applications of titanium. PM technologies and the consolidation of these new powders are now economically viable with the potential cost of the new powders running approximately an order of magnitude less than conventional PM grade powders. This paper will present the current status of “Project Black Ti” and its potential impact to the F-35 program.

Consolidation of Titanium, and Ti-6Al-4V Alloy Powders by Powder Compact Forging

Consolidation of titanium and titanium alloy powders using thermomechanical powder metallurgy (TPM) processes (powder compact forging, extrusion and rolling) is one way that can lead to cost-effective production of high value-added consolidated titanium and titanium alloy products such as near-net shaped components, tubes and plates. This paper provides an overview of the quality, microstructure (to limited depth), porosity level and mechanical properties of disks produced using open die forging of powder compacts of CP titanium and Ti-6Al-4V alloy powders. The general materials science principles underlying the relationships between processing conditions, microstructure and the mechanical properties of the disks made by using the powder compact forging are discussed.

Titanium processing: Current research and practical approaches

Over the past two years the titanium metal industry has been a focus for dynamic change and rapid growth. Driven by the large number of defense and commercial aerospace programs brought on by global economic growth and an aging fl eet, titanium supply was tight and prices high. The supply situation improved and prices declined as mill utilization ramped up and new titanium sponge production capacity came on-line. At the same time, delays in the introduction of major airframe projects and a slowing global economy eased supply concerns by stretching out delivery schedules. The aerospace industry continues to consume roughly half of all titanium and titanium alloy products currently produced, and order books continue to grow. This has been buoyed by the increased use of composite materials in new airframes, which demands an increased overall content of titanium in the structure. As much as the industry focuses on pricing and supply issues, a key to the development of more applications for titanium is processing. Low-cost titanium synthesis approaches are being developed and have been the subject of more than one TMS Titanium Committee-sponsored symposium. But even with the widespread availability of such material, processes that minimize waste, tooling, and energy consumption must be employed to extract the value in this amazing metal. This issue of JOM takes a look at current research and practical approaches in diverse application areas of titanium products. The following four articles span the size scale from tonnes of industrial mill products to grams of medical implants. We look at ways to reclaim and use lower-quality aerospace alloy material, and a novel process for making composite alloys that could fi nd application in the transportation industry. The fi rst paper, by R.D. Goin, focuses on industrial applications for titanium. Titanium or zirconium is often the material of choice for demanding corrosion conditions such as seawater desalination, power generation, or chemical processing. Cost issues can sometimes preclude their use, however, in favor of less corrosion-resistant alloys. Fusion welding of titanium to lower-cost stainless steels to create linings is not practical. Solid-state joining processes such as extrusion bonding and inertia welding can be used to fabricate bimetallic components, such as pipe and tubing, that provide a corrosion-resistant process interface with a lower-cost structural material to maximize value. The next paper, by M. Garcia de Cortazar et al., outlines research for making discontinuously reinforced titanium composites using master compounds produced by the self-propagating hightemperature synthesis approach. These compounds would enable the manufacture of chemically homogeneous titanium composite components using low-cost near-net-shape processes such as investment casting. This route avoids the isotropic property conditions sometimes seen with fi ber-wound continuously reinforced titanium-matrix composites. A range of compositions based on the addition of titanium diboride are shown, along with properties of trial castings. The paper by H. Guo et al. examines a powder sintering and forging approach on the microstructure and properties of Ti-10V-2Fe-3Al alloy. Often used as a structural alloy in aerospace applications, ingots of Ti-10-2-3 can be subject to a condition known as “beta fl eck” from chemical segregation of alloy elements that stabilize the beta phase. This condition can be cause for rejection of an ingot or component on quality grounds. This paper explores a route for processing Ti-10-2-3 with beta fl eck by employing the hydridedehydride process to break the bulk material down into a powder form. The powder is then blended and processed by a variety of standard powder metallurgy (PM) techniques and isothermal forging to full density. Mechanical properties are compared with values from the literature. Finally, we take a trip inside the human body to explore new designs and production of customized Ti-6Al-4V dental implants with the paper by G. Chahine et al. This is a fascinating approach whereby researchers are creating replicas of a patient’s actual tooth, root and all, in titanium from a computer-assisted design fi le using a net-shape electron beam fabrication technique. This, along with the ability to customize the structure of the implant for optimal anchoring and bone in-growth, points to an improved approach to dental implants that speeds healing, improves comfort, and can provide longer service life of the prosthesis. Productivity can be maximized at low overall cost by taking advantage of the capability to fabricate a large number of custom implants simultaneously.

Spongy titanium alloyed with oxygen for the production of titanium alloys

We study the influence of alloying of spongy titanium with oxygen on the structure, mechanisms of fracture, and mechanical properties of titanium. It is shown that, within the range of concentrations 0.05-0.30%, oxygen insignificantly affects both the structure and the mechanism of fracture of cast titanium but strongly increases its strength with preservation of plasticity within the admissible range specified for standard titanium alloys of this grade.

Production of titanium and titanium alloys by electrochemical reduction of oxide precursors

The direct reduction of titanium oxides has been investigated at several research organisations worldwide in search of a replacement for the current method of titanium metal production: the Kroll process. By cathodically polarising oxide feedstock of varying composition, both commercial purity titanium and titanium alloys have been produced, including the shape memory alloy Ni–Ti and novel compositions such as Ti–W. The reduction pathway has shown to be via a series of lower oxides and titanate species, with critical ramifications for process optimisation. Research continues on improving the process current efficiency and development of a suitable inert anode material.

Surface Modification for Orthopaedic Titanium Alloy by Wide-Area Electron Beam

Wide-area electron beam (WAEB) irradiation was proposed as a new surface-finishing process for orthopaedic titanium alloy products. The surface roughness could be reduced from Rz = 10 μm to Rz = 0.7 μm all over the wide circular surface within a diameter of 60 mm in just a few minutes under optimum electron beam conditions. In this paper, the surface structure and the surface characteristics of WAEB-irradiated surface are discussed. The crystal grain size becomes small and the microstructure in the surface vicinity changes under WAEB irradiation. The corrosion resistance and the repellency can be improved simultaneously with the surface smoothing. Therefore, the WAEB irradiation method enables highly efficient surface smoothing and surface modification of orthopaedic titanium alloy.

Production of titanium alloys for advanced aerospace systems by powder metallurgy

Titanium alloys parts are ideally suited for advanced aerospace systems because of their unique combination of high specific strength at both room temperature and moderately elevated temperature, in addition to excellent corrosion resistance. Despite these features, use of titanium alloys in engines and airframes is limited by cost. The alloys processing by powder metallurgy eases the obtainment of parts with complex geometry. In this work, results of the Ti-6Al-4V and Ti-13Nb-13Zr alloys production are presented. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering between 900 up to 1500 °C, in vacuum. Sintered samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively. It was shown that the samples were sintered to high densities and presented homogeneous microstructure from the elements dissolution with low interstitial pick-up.

Производство титановых сплавов и деталей экономичным методом порошковой металлургии для широкомасштабного промышленного применения

Производство титановых сплавов и деталей экономичным методом порошковой металлургии для широкомасштабного промышленного применения