Titanium Alloy Ti6Al4V Research Articles

Oxidation and wear behavior of CrAlMoN with varied Mo-content for cutting Ti6Al4V

The cutting of difficult to machine materials such as titanium alloys is challenging for the machining industry. In case of the titanium alloy Ti6Al4V, the properties of the material cause high temperatures, mechanical loads as well as high frequency vibrations at the cutting edge, leading to premature tool failure. The use of uncoated carbide tools is very common for machining of Ti based alloys. However, temperature active, self-lubricating physical vapor deposition (PVD) coatings like CrAlMoN showed promising results to reduce friction and wear during turning of Ti6Al4V. In the present study, self-lubricating (Cr34Al41Mo25)N, (Cr29Al36Mo35)N and (Cr25Al31Mo44)N coatings were investigated on cemented carbide tools. These were deposited by a hybrid process combining direct current Magnetron Sputtering and High Power Pulsed Magnetron Sputtering. Coating morphology, thickness, chemical composition, indentation hardness and modulus at ϑ = 20 °C, ϑ = 200 °C, ϑ = 400 °C and ϑ = 600 °C as well as the oxidation behavior were analyzed. Moreover, wear development after cutting tests using a CNC-lathe was investigated. Independent of Mo-content, all coating variants possessed a dense morphology and a smooth surface topography, as well as a coating adhesion class of HF1 to the cemented carbide substrate in Rockwell indentation tests according to DIN 4856. With an increasing amount of Mo, heat treatment temperature and time, more self-lubricating molybdenum oxides such as MoO3 and Mo4O11 were detected by Raman spectroscopy. Therefore, the coating with the highest amount of Mo possessed the highest amount of molybdenum oxides. After cutting tests, molybdenum oxides were also found on the tool flank face by Raman spectroscopy. The level of flank wear land width decreased with increasing amount of Mo.

Features of Structure and Properties of Lap-Welded Joints of Aluminum Alloy Al–4Cu–1Mg with Titanium Alloy Ti–6Al–4V, Obtained by Friction Stir Welding

Lap-welded joints between Ti–6Al–4V and Al–4Cu–1Mg were obtained using water-cooling-bath friction stir welding at different FSW tool rotation rates. The increase in the tool rotation rate from 350 to 375 RPM leads to better plasticization of the titanium alloy, elimination of stir zone defects, better interlocking and bonding with the aluminum alloy as well as the formation of intermetallic Al–Ti compounds (IMC), preferentially of the Al3Ti type. Shear-loading testing showed the best result was at the level of 3000 N with 2 mm of displacement. Increasing the FSW tool rotation rate to 400 and 450 RPM resulted in the formation of more IMCs, which had a detrimental effect on both maximum load and displacement achieved in the shear tests.

Surface Modification of Ti6Al4V ELI Titanium Alloy by Poly(ethylene-alt-maleic anhydride) and Risedronate Sodium.

With the simultaneous increase in the number of endoprostheses being performed, advances in the field of biomaterials are becoming apparent-whereby the materials and technologies used to construct implants clearly improve the implants' quality and, ultimately, the life of the patient after surgery. The aim of this study was to modify the titanium alloy Ti6Al4V ELI used in the construction of hip joint endoprostheses. This is why the continuous development of biomaterials is so important. This paper presents the results of research for a new application of polymer poly(ethylene-alt-maleic anhydride) as a drug release layer, placed on the surface of a titanium alloy. The obtained layers were analyzed using Raman spectroscopy (spectra and maps), Fourier transform infrared spectroscopy (spectra and maps), contact angle measurements as well as scanning electron microscopy and energy dispersive spectroscopy imaging and topography analysis. The results confirmed that the polymer layer obtained on the plate surface after the alkali heat treatment process is much better-it binds much more polymer and thus the applied drug. In addition, a longer and more gradual release of the drug was observed for the alkali heat treatment modification than for H2O2 solution.

Improved seawater corrosion resistance of electron beam melting Ti6Al4V titanium alloy by plasma nitriding

Electron beam melting (EBM) is an additive manufacturing technology that allows flexible processing of parts with complex shapes, but the product surface is usually rough and porous, which affects its corrosion resistance. In this study, the plasma nitriding has been conducted on electron beam melted Ti6Al4V titanium alloy. The samples were analyzed using X-ray diffraction (XRD), optical microscope (OM), scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscope (HRTEM). The results showed that the plasma nitriding-treated EBM sample (PN-EBM) exhibited better corrosion resistance in natural seawater than the EBM sample due to the generation of a ∼16 μm compound layer, which can effectively prevent the intrusion of harmful ions and enhance the corrosion resistance of the EBM titanium alloy.

Antibacterial Structure Design of Porous Ti6Al4V by 3D Printing and Anodic Oxidation.

Titanium alloy Ti6Al4V is a commonly used bone implant material, primarily prepared as a porous material to better match the elastic modulus of human bone. However, titanium alloy is biologically inert and does not have antibacterial properties. At the same time, the porous structure with a large specific surface area also increases the risk of infection, leading to surgical failure. In this paper, we prepared three porous samples with different porosities of 60%, 75%, and 85%, respectively (for short, 3D-60, 3D-75, and 3D-85) using 3D printing technology and clarified the mechanical properties. Through tensile experiments, when the porosity was 60%, the compressive modulus was within the elastic modulus of human bone. Anodic oxidation technology carried out the surface modification of a 3D-printed porous titanium alloy with 60% porosity. Through change, the different voltages and times on the TiO2 oxide layer on the 3D-printed porous titanium alloy are different, and it reveals the growth mechanism of the TiO2 oxide layer on a 3D-printed unique titanium alloy. The surface hydrophilic and antibacterial properties of 3D-printed porous titanium alloy were significantly improved after modification by anodic oxidation.

Electron Beam Welding Process for Ti6Al-4V Titanium Alloy.

The electron beam welding process of titanium alloys induces a series of physicochemical changes in the material that remain a relevant and necessary area of investigation. A necessary step performed after the electron beam welding process of titanium alloys in the Ti6Al-4V grade to mitigate the resulting thermal stresses is the post-weld heat-treatment process conducted through stress relieving. This study presents the comparative analysis results of the mechanical properties and structure of the Ti6Al-4V titanium alloy after electron beam welding and subsequent stress-relieving heat treatment at a temperature of 590 °C for 2 h. The analysis focused on the levels of mechanical properties such as microhardness in the heat-affected zone and weld, tensile strength, and microstructure analysis in the heat-affected zone and weld. The aim of the research was to answer the questions regarding whether the post-weld heat treatment through stress relieving after electron beam welding of the Ti6Al-4V titanium alloy would significantly affect the changes in mechanical properties and microstructure of the alloy and whether the applied welding speed in the study would cause a significant depletion of alloying elements in the material. During the course of the study, it was found that conducting the electron beam welding process at a speed of 8 mm/s resulted in a depletion of one of the alloying elements (aluminum) in the face area. However, the decrease in aluminum content was not significant and did not exceed the critical value of 6% specified in the material standards, which determined the material's application based on its strength properties.

Heterostructures Based on Noble Metal Films with Ag and Au Nanoparticles: Fabrication, Study of In Vivo Biocompatibility and Antibacterial Activity

In this work, approaches to the formation of multifunctional film heterostructures based on noble metals for the modification of the surface of implant materials (titanium alloy TiAl6V4 and carbon-fiber-reinforced polyetheretherketone CFR-PEEK) are developed. Such heterostructures consist of continuous layers of platinum (Pt) or iridium (Ir) and antibacterial components on their surface, namely silver (nanoparticles or discontinuous films) and gold (nanoparticles). Chemical or physical gas-phase deposition methods were used for their preparation. The influence of the concentration and form of the antibacterial component on the antibacterial activity and in vivo biocompatibility of the film structures was evaluated for the first time. Differences in the dynamics of silver dissolution depending on Ag concentration in the sample and the type of bottom surface (the noble metal layer = Ir, Pt or TiAl6V4) surfaces allowed us to better understand the nature of the antibacterial action against Staphylococcus aureus and Pseudomonas aeruginosa (S. aureus and P. aeruginosa) of Ag/M heterostructures. From in vivo histological studies using rats, the best biocompatibility was shown by the Ag/M heterostructure with a prolonged release of the low fraction of antibacterial component (Ag).

A green machining study to investigate the effect of nano-cutting fluid environments on the machinability of Ti6Al4V titanium alloy

This study primarily focuses on green machining, which refers to the environmentally friendly machining of parts without compromising the environment and human health. Green machining, an innovative approach in the manufacturing industry, aims to reduce the environmental impact and promote sustainable practices throughout the machining process. Green machining involves the utilization of methods such as machining, dry machining, high-performance cutting, hybrid machining, and high-speed cutting, along with environmentally friendly lubrication practices. The objective of this research is to investigate the effects of machining Ti6Al4V alloys, a widely used lightweight metal in the aerospace industry known for its challenging machinability. The study specifically examines cutting force, surface roughness, and tool wear under various cutting parameters and tribological conditions. The use of a new lubrication/cooling method was investigated in order to minimize the effects of traditional cutting fluids used in the machining of difficult materials, which may cause environmental and human health. This way, sustainable green production compatible with the environment has been realized today, where global warming and carbon emissions are rapidly increasing. In addition, it was observed that the factor determining the cutting force was the depth of cut and the feed rate was the most significant factor affecting the surface roughness.

Electrospark Cu[sbnd]Ti coatings on titanium alloy Ti6Al4V: Corrosion and wear properties

Nowadays, copper-titanium coatings have invited extensive attention from researchers in the surface modification of industrial and biomedical materials due to their excellent mechanical properties and biocompatibility. The electrospark deposition technique was used for CuTi coatings deposition on the Ti6Al4V alloy by processing in a mixture of copper and titanium granules at a copper concentration from 10 to 90 at.%. For the first time, electrospark CuTi coatings with a wide range of copper and titanium ratios are obtained on Ti6Al4V titanium alloy. It is revealed that both cathode mass gain and coatings thickness rise with the copper concentration increase in the mixture of granules. According to EDS analysis, the copper concentration in the coating linearly grew with a growth of its content in the mixture of granules. According to the data of X-ray analysis, intermetallic compounds were found in the structure of the coatings: CuTi3, CuTi, Cu4Ti3, and Cu3Ti. Detected phases provide the coating microhardness up to 6.7 GPa. Polarization tests in 3.5 % NaCl solution showed corrosion resistance growth with a copper content decrease in CuTi coatings. The oxidation resistance at a temperature of 900 °C grows with an increasing copper concentration in the coating structure. Cu-enriched sublayer is formed on upper layers of Ti6Al4V alloy after CuTi coating oxidation at 900 °C. The wear rate of the coated samples as a function of copper concentration had the form of a parabola, with a minimum for the coating made in an equimolar mixture of copper and titanium. The use of electrospark CuTi coatings makes it possible to increase the wear resistance of the Ti6Al4V alloy surface up to 11 times.

Impact of Post-Process Heat Treatments Performed on Ti6Al4V Titanium Alloy Specimens Obtained Using LPBF Technology

Additive manufacturing technology has emerged over the past decade as one of the best solutions for building prototypes and components with complex geometries and reduced thicknesses. Its application has rapidly spread to various industries, such as motorsport, automotive, aerospace, and biomedical. In particular, titanium alloy Ti-6Al-4V, due to its exceptional mechanical properties, low density, and excellent corrosion resistance, turns out to be one of the most popular for the production of parts with additive manufacturing technology across all the market segments listed above. However, when producing components using Laser Powder Bed Fusion (LPBF) technology, it is always necessary to perform appropriate heat treatments whose main purpose is to reduce the residual stresses typically generated during the manufacturing process. Post-process heat treatments on Ti6Al4V components obtained by way of additive technology have been extensively studied in the literature, with the aim of identifying optimal thermal cycles, which may allow for the effective reduction of residual stresses combined with proper microstructural conditions. However, despite the usual target of maximizing relevant mechanical properties, it is mandatory for industrial production to achieve a robust process, i.e., minimizing the sensitivity to noise-induced variation. Therefore, the aim of the present work is to compare several post-process heat treatment strategies by performing different thermal cycles in the temperature range of 750–955 °C and investigating how these affect the average mechanical properties and their variance. The treated samples are then analyzed running a complete mechanical and microstructural characterization, and the latter particularly focused on the determination of the typical microstructure present in the treated samples by using the XRD technique.

Evaluation of the Vibration Signal during Milling Vertical Thin-Walled Structures from Aerospace Materials.

The main functions of thin-walled structures-widely used in several industries-are to reduce the weight of the finished product and to increase the rigidity of the structure. A popular method for machining such components, often with complex shapes, is using milling. However, milling involves undesirable phenomena. One of them is the occurrence of vibrations caused by the operation of moving parts. Vibrations strongly affect surface quality and also have a significant impact on tool wear. Cutting parameters, machining strategies and tools used in milling constitute some of the factors that influence the occurrence of vibrations. An additional difficulty in milling thin-walled structures is the reduced rigidity of the workpiece-which also affects vibration during machining. We have compared the vibration signal for different approaches to machining thin-walled components with vertical walls made of Ti6Al4V titanium alloy and Inconel 625 nickel alloy. A general-purpose cutting tool for machining any type of material was used along with tools for high-performance machining and high-speed machining adapted for titanium and nickel alloys. A comparison of results was made for a constant material removal rate. The Short-Time Fourier Transform (STFT) method provided the acceleration vibration spectrograms for individual samples.

Tribological properties of Ti-N compound layer formed on Ti6Al4V by HCD assisted plasma nitriding

In order to improve the wear resistance of titanium alloy Ti6Al4V, an adherent Ti-N compound layer was formed on it by hollow cathode discharge (HCD) assisted plasma nitriding in a mixture gas of NH3 and N2 with a ratio of 1:2. After processing at 750 °C for 8 h, a 4 µm thick Ti-N compound layer with high hardness was produced. X-ray diffraction analysis showed that this layer is composed of TiN and Ti2N. Pin-on-disc wear tester in dry sliding condition was used to evaluate the tribological properties. Scanning electron microscopic examination and EDS measurement of unnitrided and nitrided samples were performed after the wear tests. The wear resistance of titanium alloy was greatly enhanced after plasma nitriding.

Laser melting deposition of Inconel625/Ti6Al4V bimetallic structure with Cu/V interlayers

A bimetallic structure (BS) made of Inconel625 (IN625) nickel-base superalloy with excellent high temperature properties and Ti6Al4V (TC4) titanium alloy with a light weight and a high strength has broad application prospects in aerospace engineering. However, the integrated manufacturing of the IN625/TC4 BS is a difficult research topic in the industry. In this work, the laser melting deposition (LMD) technology was used to prepare an IN625/TC4 BS without cracks and other metallurgical defects by adding Cu/V interlayers. The results show that the IN625/TC4 BS structure from the IN625 side to the TC4 one can be divided into four regions: IN625 region (region A) → Interlayers/IN625 transition region (region B) → TC4/Interlayers transition region (region C) → TC4 region (region D). The phase compositions of these regions are: γ-Ni + laves → (Ni, Cu)ss + (V, Cr)ss + TiNi → α-Ti + β-Ti + Ti2Ni → α-Ti + β-Ti. The Vickers hardness distribution is uneven in all regions, and the highest value (about 590.0 HV) is achieved in region B. The tensile strength of the IN625/TC4 BS with Cu/V interlayers reaches nearby 514.5±9.5 MPa at room temperature, and fractures are initiated in region B.

Microstructure effects on surface integrity in slot micro-milling multiphase titanium alloy Ti6Al4V

Material microstructure in micro-cutting, such as the phase boundary for multiphase material, plays a dominant role in governing the surface integrity that strongly influences the fatigue life of micro-components with complex structures. In the present study, surface formation, subsurface deformation, and subsurface microstructure evolution for the machined surface were investigated by slot micro-milling multiphase titanium alloy Ti6Al4V in terms of chip morphology, burrs formation, surface roughness, surface defects, and subsurface deformation. In particular, the effect of β-Ti was considered in the study. The results show that the machined surface shows the obvious feed marks and adhesive materials accompanied by squeezed β-Ti, split β-Ti and plastic side flow β-Ti. The subsurface of the machined surface can be divided into the amorphous layer (around 24 nm), nanocrystalline layer (around 124 nm), elongated grain layer (around 197 nm), and bulk material. The deformation layer thickness of the β-Ti zone is larger than the α-Ti zone. In the deformation layer of the machined subsurface, the synergetic deformation between α-Ti and β-Ti can lead to the formation of a large number of nanocrystalline grains and some enlarged grains in the phase boundary of the α-Ti side, and the β-Ti side is full of elongated grains and sporadic dynamic recrystallization nanocrystalline. Our study enhances the understanding of the surface formation and subsurface formation mechanism in micro-milling Ti6Al4V, which can provide a theoretical basis and practical reference for achieving high surface integrity for polycrystalline or multiphase material by micro-milling.

Optimization of EDM parameters using Ananya algorithm: A new advanced optimization technique

Titanium alloys are nowadays machined using electric discharge machining (EDM). EDM is an unconventional machining tool which is used to produce complex geometric profiles. The major limitation of EDM machining is the low material removal rate (MRR) hence the MRR need to be maximized. There are so many modeling techniques available nowadays like regression modeling, response surface modeling, artificial neural network etc. Optimization frequently relies on the use of a predictive model for achieving the best possible outcomes. Through the utilization of a computer and a well-suited optimization algorithm, it becomes feasible to attain an optimal result. Nowadays metaheuristic-based optimization techniques are very popular for optimization because traditional optimization is often unable to solve this type of problem. The result is either the optimum one or very near to the optimum solution. Genetic algorithm (GA), particle swarm optimization (PSO), and Ant colony optimization (ACO) is more popular algorithm nowadays. This research paper shows the EDM parameter optimization of MRR and tool wear rate (TWR) for titanium alloy Ti6Al4V. The Ananya algorithm is used to optimize the MRR and TWR. Ananya algorithm is very simple and easier to implement. Furthermore, it always achieved optimum solutions in every run. Ananya algorithm is compared to other algorithms.

Effect of Copper Percentage in Copper Tungsten Electrode on Ti6Al4V by Electrical Discharge Machining

The aim of this study was to identify the optimal parameters for electrical discharge machining of Ti6Al4V titanium alloy using copper tungsten electrodes with tungsten compositions of 70% and 80%, respectively. The experiment involved varying current, pulse on time, and duty factor were determined using the Taguchi experimental method L-18 orthogonal arrays. The level of importance of each machining parameter on material removal rate (MRR) was determined using analysis of variance (ANOVA), and the optimal machining parameter combination was obtained using the analysis of signal-to-noise (S/N) ratio. The results showed that a Cu30/W70% electrode performed the best in terms of MRR, electrode wear, and surface roughness. The optimal machining conditions for achieving maximum MRR were found to be a current of 30 A, a pulse on time of 50 μs, and a duty factor of 40%.

CORROSION RESISTANCE OF A GOLD-TITANIUM ALLOY TI6AL4V WELD PRODUCED IN A DENTAL LASER WELDING MACHINE

The corrosion resistance of the Ti6Al4V titanium alloy in combination with gold may increase or decrease, which is related to the amount of gold in the alloy. The aim of the work was to assess the weldability of pure gold with the Ti6Al4V titanium alloy using a prosthetic laser welding machine, and to assess the corrosivity. In the research was used a calibrated 24k gold wire with a diameter of 0.4 mm. The wire was welded to the surface of the Ti6Al4V titanium screw used in the connection of the prosthetic superstructure connector with an implant. For welding, a Bego Laser Star plus prosthetic laser welding machine was used. The samples were placed in resin, ground (500-4000 SiC), polished (Al2O3 slurry. An electrochemical corrosion test was carried out, simulating the potential formation of pitting corrosion, in a solution of artificial saliva, consisting of two stages: a. determination of the stationary potential in no-current conditions for 1 h until stabilization (Eocp - opec circuit potential), b. potentiodynamic test initial potential E start = Eocp-100 mV to E final = 2 V or the occurrence of the second condition: anode current density 1 mA /cm2, the potential increase rate of 1 mV/s, and then the samples were observed using light microscopy and SEM, and an attempt was made to identify corrosion products using EDS. The paper evaluates the possibility of gold welding with the Ti6Al4V titanium alloy in the conditions of a prosthetic laboratory, limitations in this process were indicated, and conclusions that could improve weldability were indicated. The heat affected zone was identified and the results of corrosion tests were evaluated. The weldability of gold with the mentioned titanium alloy was confirmed, however, in subsequent tests, attempts should be made to reduce the laser spot, which will reduce the heat affected zone. Traces of corrosion were found, but they were rare and even over the entire surface of the samples.

Investigation on surface quality in micro milling of additive manufactured Ti6Al4V titanium alloy

The additive manufactured technology is widely applied to produce titanium alloy parts with complex structures. The subsequent machining operations are necessary for additive manufactured parts to achieve the required machining quality. In this paper, the theoretical surface roughness model in micro milling was established. The model indicated the theoretical milled roughness mainly depends on the feed per tooth, tool nose radius and bottom edge inclination angle. Then, micro milling experiments are conducted on additive manufactured titanium alloy using PCD micro end mill. The surface roughness on milled surface was measured and investigated. At the middle position of micro milled surface, the distribution curves of surface roughness Ra and Sa show the same variation trend under different milling parameters. Moreover, the measured surface roughness results on different transverse positions of milled surface showed that the difference value between the actual and theoretical surface roughness of milled surface is mostly induced by the unstable cutting behaviors, which is also mainly responsible for the surface roughness size effect. The transverse distribution of surface roughness on milled surface exhibited a W shape because of the variation of the instantaneous undeformed chip thickness and material removal mode at different transverse positions.

Surface polishing of additively manufactured Ti6Al4V titanium alloy by using a nanosecond pulse laser

Surface polishing of additively manufactured Ti6Al4V titanium alloy by using a nanosecond pulse laser

Study on joint characteristics in laser butt welding of AMed and wrought Ti6Al4V plates

Titanium alloy Ti6Al4V has been widely applied to medical, automotive, and aerospace industries due to its excellent properties such as high strength and excellent corrosion resistance. On the other hand, additive manufacturing (AM) technology can give the freedom of design of the products. In order to spread the AMed products, the joining of AMed and wrought products are required, and it is important to understand the joint characteristics. In this study, butt welding of Ti6Al4V plate was conducted by fiber laser in argon shielding, and the joint characteristics of laser weld wrought/wrought, AMed/AMed, and AMed/wrought Ti6Al4V plates were experimentally investigated. The AMed plate has higher tensile strength than wrought plate but the elongation of AMed plate is smaller, since AMed plate has α’ martensite due to rapid cooling during laser irradiation in AM process. Then, the laser weld joint of AMed/AMed plates has higher tensile strength, but smaller elongation than that of wrought/wrought plates. The weld joint of AMed/wrought plates shows good welding state, since small heat input leads to formation of small weld bead with higher hardness between wrought and AMed plates.