Papers by Keyword: Titanium Alloy

Abstract: The main purpose of this paper is to analyze the values of the temperature after turning of pure titanium and its alloy, Ti6Al4V, as function of different cutting parameters (rotational speed, feed and depth of cut). Based on an infrared thermometer measurements for dry turning, with un-coated carbide insert, graphically dependencies of temperature as function of the cutting parameters are presented for the both materials.

Abstract: Additively manufactured titanium alloys such as Ti-6Al-4V have been used as functional components in industry due to their excellent mechanical properties. However, the machining of these alloys is a challenge due to their enhanced tensile/yield strength, low elastic modulus, poor thermal conductivity, and microstructural anisotropy. Thermal assisted machining (TAM), as a hybrid manufacturing technology, can improve the machinability of additively manufactured alloys. The main aim of this paper is to investigate the effect of temperature buildup on the machinability of additively manufactured Ti alloy with different build directions in the TAM process. It was found that the surface integrity was notably enhanced by preheating, and it was the best at 90° build orientation. Serrated chips were generated at room temperature, and curlier chips were formed in high-preheating machining environment. By analyzing the surface quality, the influence of the build-up orientation on the surface quality at different temperatures was evaluated.

Abstract: Modern manufacturing increasingly demands energy-and resource-efficient solutions. Conventional metal forming often requires high temperatures to reduce flow stress, resulting in high energy consumption, especially for low-formability alloys. Electrically-Assisted Manufacturing (EAM) has emerged as a promising alternative, leveraging the electroplastic effect, i.e. electricity’s direct influence on plastic deformation. Documented benefits include reduced forming forces, improved ductility, and altered fracture modes. Indeed, integrating electroplasticity into manufacturing aligns with Industry 4.0 and decarbonization goals, enabling lower energy consumption, extended tool life, and greater compatibility with renewable energy sources. This study compares conventional tensile testing and electro-assisted tensile testing (EAM) of Ti6Al4V, evaluating both mechanical results and the energy consumption of the testing machine under different conditions. The comparison results highlight the potential of pulsed current to improve material formability while reducing energy consumption, offering a more sustainable approach to manufacturing.

Abstract: Electroplasticity in sheet metal forming is a relatively recent method that involves applying an electric current to metal sheets during or before the forming process. Existing research on Electro-Assisted (EA) forming primarily focused on material characterization; few studies have investigated the effect of electropulsing on loads, power, and energy consumption during sheet metal forming, and no studies have explored the reshaping of previously formed titanium sheets after the Electro-pulsed treatment (EPT). This research aims to bridge some of these gaps of knowledge by applying two different electropulsing treatments, varying in current density, to square Ti6Al4V specimens prior to shaping and reshaping. performed using dies and counter dies having different geometries. Load, power, and energy consumption data were measured to assess the benefits of EPT compared to an untreated specimen serving as a reference. The findings suggest that EPT can significantly reduce the energy consumption and forces required for both shaping and reshaping of titanium components, extending their useful life and reducing the need for remelting. The study highlights the potential of EPT as a sustainable solution for reducing the environmental impact of titanium sheet disposal and recycling, improving material efficiency, and optimizing industrial forming processes.

Abstract: Surface modification of metallic materials to impart antibacterial properties has attracted significant attention for practical applications in biomedical and industrial fields. This study aims to characterise the antibacterial surface textures of Ti alloys (Ti-6Al-4V) and investigate their relationship with water repellency, bio-adhesion resistance, and antibacterial performance. Two distinct surface textures were fabricated using chemical (acid treatment for 5 and 20 min) and physical methods (tensile testing). Antibacterial tests revealed 41.6%, 14.6%, and 31% reductions in the viable bacterial counts for the 5-minute acid-treated, 20-minute acid-treated, and tensile-tested samples, respectively, compared to untreated controls. Contact angles of 100.9°, 96.1°, and 79° were observed, indicating varying degrees of water repellency. The acid-treated samples exhibited reduced bio-adhesion, whereas the tensile-tested samples showed increased bio-adhesion. These findings suggest that the surface morphology that inhibits bacterial aggregation is the primary factor contributing to antibacterial properties. Although water repellency and bio-adhesion resistance are often associated with antibacterial surfaces, they serve as functional correlations rather than direct determinants. The surface texture developed in this study exhibited a symmetrical vertical height distribution with Sa = 0.24 µm and featured flat valley regions, rendering it highly suitable for antibacterial applications and promising for use in biocompatible environments.

Abstract: The trade-off between strength and toughness remains a major challenge in structural materials engineering, especially for titanium-based materials. This study explores the potential of titanium-based laminates for lightweight armor, aimed at improving anti-ballistic properties through the use of layered structures. Titanium alloy Ti-6Al-4V (Ti64) was combined with metal matrix composites (MMCs) reinforced with TiC or TiB particles (up to 40 vol%) using two powder metallurgy (PM) techniques. The first approach used press-and-sinter blended elemental powder metallurgy (BEPM) to create the laminates in a single step, while the second involved post-processing via hot isostatic pressing (HIP) to enhance material properties. Both fabrication methods produced laminates that significantly outperformed commercial alternatives in ballistic testing against 7.62 mm armor-piercing bullets. The use of HIP post-BEPM enhances material properties by reducing porosity and increasing hardness, highlighting the complementary nature of these technologies in producing efficient and cost-effective armor materials.

Abstract: Metallic materials with poor plasticity are usually difficult to get effective surface strengthening. To solve this problem, an innovative surface deformation technology called magnetic-assisted ultrasonic nanocrystal surface modification (MA-UNSM), was used to process Ti64 alloy in this study. It has been demonstrated that MA-UNSM leads to higher hardness, deeper plastic deformation layer, and residual stresses with higher magnitude and greater depth compared with UNSM. Specifically, the external magnetic field increased the hardness from 427.6 HV for traditional UNSM to 493.8 HV for MA-UNSM and the surface compressive residual stress (CRS) from 641 MPa to 757 MPa. It is believed that by lowering the resistance between dislocations and pinning obstacles, the magnetic field enhances the plasticity of the material, and thus more effective surface hardening.

Abstract: The quenched-in microstructures of Ti-15at%Nb-1at%O alloy after solid solution treatment (SST) in β phase for different SST times were investigated. In the as-rolled sample before SST, the α phase formed at the grain boundaries, and coarse martensite laths of α" phase formed in the grains. In the sample after SST for the time from 0.3 to 2.4 ks, a bundle-microstructure containing α" phase laths nucleating in the same crystallographical direction was formed. In the sample with SST for 4.8ks, the α" phase laths did not form in the area at a certain distance away from the grain boundaries, and the β+ω phase formed in that area. The rest of the areas were covered by the acicular laths of α" phase. The sample after SST for 10.8 ks exhibited the acicular laths of α" phase formed uniformly in the grains. The inhomogeneous oxygen distribution would significantly affect the microstructure formation of an oxygen-containing Ti-Nb alloy.

Abstract: Rolled titanium alloy has been widely applied to components in aerospace industry. The cutting force and the quality of hole are studied in drilling of countersunk hole of rolled titanium alloy with the crystallographic anisotropy. The periodical changes in the cutting force were observed in drilling of rolled titanium alloy, whereas in drilling of carbon steel, the cutting force increases without periodical changes due to isotropic material. The cutting force depends on the cutting direction angle, defined as the relative angle of the cutting direction with respect to the workpiece coordinate system. When the cutting direction is parallel to the rolling direction, the cutting direction angle is denoted as 0°, and when it is perpendicular, the cutting direction angle is denoted as 90°. The cutting force becomes stable around a cutting direction angle of 0°, while high frequency vibrations are observed in the cutting force around a cutting direction angle of 90°. The countersunk angle and the surface finish depend on the cutting direction angle. The cutting forces, then, are analyzed using an analytical force simulation. A three-dimensional chip flow is interpreted as a piling up of orthogonal cuttings containing cutting velocities and chip flow velocities. The cutting force is predicted by the determined chip flow model, where the chip flow direction is determined to minimize the cutting energy. The changes in the shear plane cutting model of rolled titanium alloy are discussed in the simulation. These findings provide better understandings of the effect of anisotropy in drilling to improve the quality of countersunk holes.

Abstract: Titanium-based materials are attractive candidates to make low-weight armor parts. However, a broad use of titanium is limited by its high cost, especially when traditional cast and wrought technology is in place. This issue requires more economical production and improved protective properties of titanium-based materials. Powder metallurgy is a valid alternative to make products less expensive, especially when low-cost hydrogenated titanium is used instead of high-quality titanium powder. For effective protection, titanium-based armor should exhibit a substantially improved combination of hardness, strength and ductility, which can be achieved by using laminate (layered) structures. In this study, laminates based on Ti-6Al-4V (wt.%) alloy and its composites reinforced with light and hard particles of TiC and TiB were made using blended elemental powder metallurgy of hydrogenated titanium. Simplest press-and-sinter option as well as additional hot isostatic pressing were tested to achieve high set of characteristics of individual layers and laminates as a whole. It has been shown that the used reinforcement presents an exceptional opportunity for hardening of Ti-based composites without compromising their low specific weight and capable of hardness increase by more than 40% compared to the base alloy. Fabricated structures were ballistic tested and compared with open data on commercial armor made of titanium.