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Titanium grade 9 (Ti-3Al-2.5V) stands out as a preferred material in various industrial applications because of its suitable properties. Its applications span diverse sectors, including precision manufacturing, where it is utilized to produce honeycomb structures for advanced aeronautics, as well as for certain biomedical components. In parallel, micro-milling has gained widespread utilization across medical, aerospace, and electronic industries due to the increasing demand for miniature products in these domains. This current research study aims to explore the impact of various micro-milling process parameters—specifically, feed rate, cutting speed, and depth of cut—on the surface quality, burr formation, and tool flank wear of titanium grade 9. Research findings reveal that the feed rate plays a major role in influencing surface roughness (contribution ratio (CR): 62.96%) and burr formation (CR: 55.20%). Similarly, cutting speed and depth of cut significantly affect surface roughness, contributing 20.32% and 9.27%, respectively, but are insignificant factors for burr width. Tool flank wear is primarily influenced by cutting speed (CR: 54.02%), with feed rate contributing 33.18%. Additionally, the feed rate and cutting speed are significant factors in determining the length of the burr, with contribution ratios of 77.70% and 7.77%, respectively. Confirmatory tests conducted at optimum parameters selected from the main effects plot validated the experimental results. [ABSTRACT FROM AUTHOR]

Nowadays, the demands for titanium alloys are drastically increasing in the manufacturing of several industrial components due to offering high strength-to-weight ratio, excellent corrosion resistance characteristics, and excellent mechanical properties. Besides, it has several adverse immanent properties like lower thermal conductivity, highly chemically reactive, and smaller elastic modulus, which makes its machining difficult. In machining titanium alloys, a higher amount of temperature is generated and is responsible for getting rapid tool wear and poor machined surface quality. However, to overcome these issues, the present research utilized a novel cooling strategy like a dual-nozzle minimum quantity lubrication (MQL) system to study the machinability behaviours of Ti–3Al–2.5V alloys in face milling using PVD-applied coated carbide insert. Also, a novel eco-friendly ZnO nanofluid was implemented as a cutting fluid and its performance was compared with Al2O3 nanofluids. The surface roughness under ZnO and Al2O3 nanofluids was obtained in the range of (0.312–1.032 µm) and (0.374–1.124 µm), respectively, while the flank wear under ZnO and Al2O3 nanofluids was obtained in the range of (0.088–0.182 mm) and (0.098–0.225 mm), respectively. Abrasion is the leading mode of wear observed under both nanofluids. Also, ZnO nanofluid-assisted milling exhibited better flatness as compared to Al2O3 nanofluid. By using the Grey-PSO optimization, the optimal input parameters for ZnO nanofluid MQL were obtained as Q = 33 ml/h, ap = 0.4 mm, f = 250 mm/min, and N = 1800 rpm, while the optimal parameter for Al2O3 nanofluid was obtained as Q = 31 ml/h, ap = 0.3 mm, f = 200 mm/min, and N = 1200 rpm. [ABSTRACT FROM AUTHOR]

Titanium grade 9 (Ti-3Al-2.5V) stands out as a preferred material in various industrial applications because of its suitable properties. Its applications span diverse sectors, including precision manufacturing, where it is utilized to produce honeycomb structures for advanced aeronautics, as well as for certain biomedical components. In parallel, micro-milling has gained widespread utilization across medical, aerospace, and electronic industries due to the increasing demand for miniature products in these domains. This current research study aims to explore the impact of various micro-milling process parameters—specifically, feed rate, cutting speed, and depth of cut—on the surface quality, burr formation, and tool flank wear of titanium grade 9. Research findings reveal that the feed rate plays a major role in influencing surface roughness (contribution ratio (CR): 62.96%) and burr formation (CR: 55.20%). Similarly, cutting speed and depth of cut significantly affect surface roughness, contributing 20.32% and 9.27%, respectively, but are insignificant factors for burr width. Tool flank wear is primarily influenced by cutting speed (CR: 54.02%), with feed rate contributing 33.18%. Additionally, the feed rate and cutting speed are significant factors in determining the length of the burr, with contribution ratios of 77.70% and 7.77%, respectively. Confirmatory tests conducted at optimum parameters selected from the main effects plot validated the experimental results.

Near alpha titanium alloys have been widely used in the aerospace industry owing to their high special strength, low-density and excellent corrosion resistance. Ti–3Al–2.5V is a typical near alpha titanium alloy that was usually used in the form of a tube in aircraft due to its excellent cold workability. In the present study, the microstructural evolution and detwinning behavior of cold-rolled Ti–3Al–2.5V alloy tubes during annealing were investigated. Upon annealing, the microstructure evolution strongly depends on the annealing temperature and holding time, which play important roles in the kinetics of the static recovery and recrystallization. In addition, there are two independent detwinning mechanisms involved during annealing. The first one is that detwinning occurs along the twin shear direction at grain boundaries, resulting in a shortening effect. The second one is that detwinning occurs in the center of twins, resulting in a thinning effect of twins. The understanding of the detwinning behavior and microstructural evolution during annealing helps with the tube processing and their applications in aircraft.

The anisotropy, which is one of key mechanical properties of Ti-alloy tubes, is usually described in terms of the contractile strain ratio (CSR) macroscopically and dependent on the micro texture evolution. In order to understand the variation of CSR , the texture evolution of Ti-3Al-2.5V titanium alloy tubes was studied by Electron Back-Scattered Diffraction (EBSD). The results show that the basal poles of the α -phase incline from the radial direction to circumferential direction and stabilize around 45° between these two directions, and the strongly preferred orientation of the β -phase is observed with the increase of axial plastic strain. This change of texture decrease the CSR values rapidly in the initial stage, then they decrease slowly until stabilizing in the final stage. The simple model between CSR and texture quantity parameter f is modified by incorporating the texture component in the axial direction. Comparison with experiment shows that the modified model is in better agreement with the experimental values than the simple model. [ABSTRACT FROM AUTHOR]

Commercial titanium alloy Ti-3Al-2.5V became one of the most widely used titanium alloys after its introduction in the early seventies. It has a very attractive combination of tensile strength, creep strength, toughness and high-temperature stability for long-term applications up to 425°C. It is used for gas turbine components and in other applications where this good combination of properties is required [1]. At the same time it has poor tribological properties that are typical of most of the titanium alloys. It has low surface hardness and wear resistance. These disadvantages of the material limit its application [1],[2]. Ti-3Al-2.5V was chosen for this experimental work because it showed a good plasma gas nitriding performance in comparison with the other alloys during the tests. [ABSTRACT FROM AUTHOR]

Titanium alloy Ti-3Al-2.5V is cheaper to produce and has the potential of improved ductility and formability compared to the Ti-6Al-4V alloy. Various heat treatments were performed on cylindrical tensile test bars in order to optimize the mechanical properties of Ti-3Al-2.5V. The tensile properties of heat-treated Ti-3Al-2.5V were determined at four annealing temperatures with different quenching methods and five different solution treatments and five different aging treatments for varying hours. The samples were tensile tested. The results indicated that optimum properties of high strength and ductility were reached at 926 °C of solution treatment and 480 °C of aging. [ABSTRACT FROM AUTHOR]

The contractile strain ratio ( CSR ) is an important index measuring the anisotropy of tubes. The values of CSR vary non-linearly with the amount of plastic deformation. However, up to now, there are no constitutive models which are able to take this variation into account. In order to obtain the actual deformation characteristics and improve the prediction capability for plastic deformation processes of anisotropic tubes, this study developed an elasto-plastic constitutive model based on Hill׳s 48 anisotropic yield function. In this constitutive model, the variation in CSR with plastic deformation was considered. A user material subroutine VUMAT incorporating the constitutive model was developed based on ABAQUS/Explicit platform. The comparisons between the finite element (FE) simulations and experiments for uniaxial tension, uniaxial compression and numerical control (NC) bending process of Ti–3Al–2.5 V titanium alloy anisotropic tube, show that this constitutive model is reliable. The simulation accuracy was improved and the plastic deformation characteristics could be better described for the anisotropic tubes by using this constitutive model. [ABSTRACT FROM AUTHOR]

Abstract: Titanium, a relatively new engineering metal, has been employed principally in high demanding industries due to its high final cost and it is well known for its biocompatibility. Powder metallurgy (PM) techniques could offer the possibility to reduce the production cost without paying it in terms of mechanical properties, thanks to their intrinsic advantages. In this study the Ti–3Al–2.5V titanium alloy was produced considering two powder production routes and sintered under different temperatures in order to address their feasibility as alternative to the wrought alloy. The results indicate that PM Ti–3Al–2.5V alloys studied have comparable mechanical behaviour as their counterpart obtained by conventional metallurgy and, therefore, are potential candidates to fabricate cheaper titanium products for structural applications as well as biomedical devices. [Copyright &y& Elsevier]

Abstract: The processing of near net shape Ti–3Al–2.5V components using the conventional pressing and sintering route is addressed in this study. The Ti–3Al–2.5V starting powder was obtained considering both the blending elemental and the master alloy addition methods. The powders were uniaxially pressed and sintered in a high-vacuum furnace under various temperature–time combinations. The influence of the processing parameters on the relative density, microstructural features, amount of interstitials, mechanical behaviour, thermal conductivity and electrical resistivity of the sintered materials was evaluated. It was found that the relative density of the samples increases with processing temperature and time, and almost fully dense materials were obtained. The mechanical performance of the Ti–3Al–2.5V improves due to the reduction of the residual porosity and are, generally, of the same order of magnitude of those required for titanium biomedical products. Furthermore, the temperatures–times selected permit to obtain thermal and electrical properties similar to the wrought alloy. [Copyright &y& Elsevier]

Abstract: This study addresses the processing of near-net-shape, chemically homogeneous and fine-grained Ti–3Al–2.5V components using vacuum hot-pressing. Two Ti–3Al–2.5V starting powders were considered. On one side, hydride–dehydride (HDH) elemental titanium was blended with an HDH Ti–6Al–4V prealloyed powder. On the other side, an Al:V master alloy was added to the HDH elemental titanium powder. The powders were processed applying a uniaxial pressure of 30 MPa. The sintering temperatures studied varied between 900 °C and 1300 °C. The relative density of the samples increased with processing temperature and almost fully dense materials were obtained. The increase of the sintering temperature led also to a strong reaction between the titanium powders and the processing tools. This phenomenon occurred particularly with boron nitride (BN) coating, which was used to prevent the direct contact between titanium and graphite tools. The flexural properties of the Ti–3Al–2.5V samples increased with vacuum hot-pressing temperature and are comparable to those specified for wrought titanium medical devices. Therefore, the produced materials are promising candidates for load bearing applications as implant materials. [Copyright &y& Elsevier]

Abstract: The fabrication of the workhorse Ti–6Al–4V alloy and of the Ti–3Al–2.5V alloy was studied considering the master alloy addition variant of the blending elemental approach conventionally used for titanium powder metallurgy. The powders were characterised by means thermal analysis and X-ray diffraction and shaped by means of uniaxial pressing. The microstructural evolution with the sintering temperature (900–1400°C) was evaluated by SEM and EDS was used to study the composition. XRD patterns as well as the density by Archimedes method were also obtained. The results indicate that master alloy addition is a suitable way to fabricate well developed titanium alloy but also to produce alloy with the desired composition, not available commercially. Density of 4.3g/cm3 can be obtained where a temperature higher than 1200°C is needed for the complete diffusion of the alloying elements. Flexural properties comparable to those specified for wrought Ti–6Al–4V medical devices are, generally, obtained. [Copyright &y& Elsevier]

Abstract: The applicability of irregular prealloyed Ti–6Al–4V powder for the fabrication of titanium products by pressing and sintering and its employment as a master alloy to obtain the Ti–3Al–2.5V alloy was studied. To this end, the starting powders were characterised by dilatometry, differential thermal analysis and XRD. Green samples were obtained by cold uniaxial pressing, and the evolution of the microstructure over the sintering temperature range 900–1400°C was studied. The variation of the final density and mechanical properties with the sintering temperature was considered. Based on the study carried out, it can be stated that more reliable powders are needed to open the titanium market to new applications. A relative density of 95% and diverse microstructural features and mechanical properties equivalent to those of biomedical devices can be obtained by the pressing and sintering route. [Copyright &y& Elsevier]

Abstract: Inductive hot-pressing is a field-assisted sintering process (FAST) in which an electrical current is used to enhance the densification of the powder. Inductive hot-pressing could be employed to enable titanium powder to reach a higher density in less time than the pressing and sintering process. In this study, titanium and titanium alloy powders with different features were processed by means of inductive hot-pressing. The influence of processing temperature on density, microstructure, quantity of interstitial elements and hardness was investigated. Generally, practically fully dense materials were obtained without any carbon pick-up, even if the materials were in contact with the graphite matrix during processing. Nevertheless, there was an increment of the nitrogen content and some oxygen pick-up, especially for the powders with smaller particle size. Hardness is not significantly affected by the pressing temperature, but it strongly depends on the amount of interstitials. [Copyright &y& Elsevier]

Abstract: Defects on external surface of in-service hydraulic tubes can reduce total life cycles for operation. Evaluation of fatigue life of the tubes with damage is thus critical for safety reasons. A methodology of generating defects in the Ti–3Al–2.5V tube—a widely used pipeline in hydraulic systems of aircrafts—using nanosecond pulsed laser for experimental fatigue life study is described in this paper. Straight tubes of five different sizes were laser micromachined to generate notches of given length and depths on the outside surface. Approaches were developed to precisely control the notch dimensions. The laser-notched tubes were tested with cyclic internal impulse pressure and fatigue life was measured. The laser notches and fatigue cracks were characterized after the test. It is concluded that laser micromachining generated consistent notches, and the influence of notch depth on fatigue life of the tube is significant. Based on the experimental test results, the relationship between the fatigue life of the Ti–3Al–2.5V tube and the notch depth was revealed. The research demonstrated that laser micromachining is applicable for experimental fatigue life study of titanium tubes. The presented test data are useful for estimating the damage limits of the titanium tubes in service environment and for further theoretical studies. [Copyright &y& Elsevier]