6Al 4V Alloy Research Articles

Mechanical energy absorption capacity of the porous Ti-6Al-4V alloy under quasi-static and dynamic compression

Porous materials are very efficient in absorbing mechanical energy in different applications. In the present study, porous materials based on the Ti-6(wt.%)Al-4V alloy were manufactured with the use of two different powder metallurgy methods: i) blended elemental powder approach using titanium hydride (TiH2) as well as V-Al master alloy powders and ii) using hydrogenated Ti-6-4 pre-alloyed powder. The powder compacts were sintered with additions of ammonium bicarbonate as a pore-holding removable agent. The emission of hydrogen from hydrogenated powders on vacuum sintering and the resulting shrinkage of powder particles permitted the control of the sintering process and creation of anticipated porous structures. Mechanical characteristics were evaluated under quasi-static and dynamic compressive loading conditions. Dynamic compression tests were performed using the direct impact Hopkinson pressure bar technique. All investigations aimed at characterizing the mechanical energy-absorbing ability of the obtained porous structures. The anticipated strength, plasticity, and energy-absorbing characteristics of porous Ti-6-4 material were evaluated, and the possibilities of their application were also discussed. Based on the obtained results, it was found that porous Ti-6-4 material produced with a blended elemental powder approach showed more promising energy absorption properties in comparison with pre-alloyed powder.

A Study on Compressive Behaviour of Thermal Cycled Titanium Alloy

Abstract: Now a day, the titanium was recognized for its strategic importance as a unique lightweight, high strength alloyed structurally efficient metal for critical, high-performance aircraft, such as jet engine and airframe components. Titanium -6Al4v alloy is an alpha + beta alloy, which generally contains alpha and beta stabilizers and is heat treatable to various degrees. Over 70% of all Titanium alloy grades melted on a sub grade of Ti-6A1-4v which is used in aerospace, air frame and engine components. , Titanium alloy (Ti-6Al-4v) is heat treated for two different methods in order to get optimum combination of ductility, machinability and structural stability by annealing and to increase the strength by solution treating. Compression test was carried out at room temperature using a Universal testing machine. The flow behavior of different heat treatment and thermal cycled specimens were studied. The comparative study of the flow behavior of titanium alloy was made.

Protection of titanium alloys against high temperature oxidation during closed-die forging: Structural analysis of the boro-silicate glass coating/Ti-6Al-4V alloy interfacial region by correlative imaging

We analyse herein the interfacial region formed between a borosilicate glass coating and Ti-6Al-4V alloy after a transient of 8 h at 1150 °C. The correlation of two optical and electron microscopy methods (Raman and Backscatter Electron Diffraction imaging) enabled an accurate description of this particular interface. This interface is composed of five different phases, namely Ti2O3, TiB2, TiB, Ti5Si3 and Ti6Si2B, and it proves to be protective against oxygen permeation. Finally, this study also enabled the development of a Raman database for Ti borides, silicides, and borosilicides, in part from experimental and more completely from theoretical (DFT computations) data.

Effect of MWCNT based Water Soluble Oil on Cutting Forces and Surface Roughness with Tool Wear in End Milling of Ti- 6Al-4V alloy

Effect of MWCNT based Water Soluble Oil on Cutting Forces and Surface Roughness with Tool Wear in End Milling of Ti- 6Al-4V alloy

High Strength Corrosion Resistant Steel for Aircraft Landing Gears and Structures

<div class="section abstract"><div class="htmlview paragraph">High stressed aircraft landing gear and structural components are subjected to severe loading, corrosion and adverse environmental conditions. Materials such as high strength steels and high-strength titanium alloys are widely used for those critical components. The main criterions for choosing the materials are their strength and fatigue strength, toughness and ductility.</div><div class="htmlview paragraph">300M steel is widely used for high stress aircraft landing gears and structures; however, this steel is not corrosion-resistant and requires protective coatings.</div><div class="htmlview paragraph">Cobalt-free, quenched and tempered high strength corrosion resistant steel alloy (“HSCR steel”) provides the same strength, ductility, and toughness as the 300M steel and while it possesses corrosion resistance in salt spray test. HSCR steel has showed no rust after the standard salt spray test in accordance with ASTM B117 using a 5% NaCl concentration, natural pH, at 95°F, for 200 hours test duration.</div><div class="htmlview paragraph">Aircraft applications of the wrought HSCR steel include landing gear components, rotatable shafts, actuators, flap tracks, slat tracks, fasteners, and others.</div><div class="htmlview paragraph">Besides forging, the aircraft components can be manufactured from HSCR steel powders by:<ul class="list disc"><li class="list-item"><div class="htmlview paragraph">Powder metallurgical-based hot isostatic pressing (PM HIP) to the near net shapes</div></li></ul></div><div class="htmlview paragraph">(NNS) followed by finish machining/surface finishing and heat treatment<ul class="list disc"><li class="list-item"><div class="htmlview paragraph">Additive manufacturing (AM) followed by surface finishing and heat treatment.</div></li></ul></div><div class="htmlview paragraph">Modification of the HSCR steel is applicable for vacuum and investment casting of aircraft hydraulic fluid system, motion control and actuation system, cargo system, and flight safety components.</div><div class="htmlview paragraph">HSCR steel is a low cost alternative of Ti-6Al-4V alloy. The components made from Ti- 6Al-4V alloy can be substituted by the same weight components made from HSCR steel due to HSCR steel possesses slightly higher specific stiffness and specific strength (ratio of modulus elasticity and ultimate tensile strength to density) and slightly lower ductility and toughness compared to Ti-6Al-4V alloy.</div><div class="htmlview paragraph">Industrial production of HSCR steel is underway.</div></div>

Cutting force prediction in ultrasonic-assisted milling of Ti–6Al–4V with different machining conditions using artificial neural network

AbstractTi–6Al–4V alloy has superior material properties such as high strength-to-weight ratio, good corrosion resistance, and excellent fracture toughness. Therefore, it is widely used in aerospace, medical, and automotive industries where machining is an essential process for these industries. However, machining of Ti–6Al–4V is a material with extremely low machinability characteristics; thus, conventional machining methods are not appropriate to machine such materials. Ultrasonic-assisted machining (UAM) is a novel hybrid machining method which has numerous advantages over conventional machining processes. In addition, minimum quantity lubrication (MQL) is an alternative type of metal cutting fluid application that is being used instead of conventional lubrication in machining. One of the parameters which could be used to measure the performance of the machining process is the amount of cutting force. Nevertheless, there is a number of limited studies to compare the changes in cutting forces by using UAM and MQL together which are time-consuming and not cost-effective. Artificial neural network (ANN) is an alternative method that may eliminate the limitations mentioned above by estimating the outputs with the limited number of data. In this study, a model was developed and coded in Python programming environment in order to predict cutting forces using ANN. The results showed that experimental cutting forces were estimated with a successful prediction rate of 0.99 with mean absolute percentage error and mean squared error of 1.85% and 13.1, respectively. Moreover, considering too limited experimental data, ANN provided acceptable results in a cost- and time-effective way.

Investigation on the Unlubricated Sliding Tribological Properties of Ti–20Zr–6.5Al–4V Alloy at Elevated Temperatures

In this study, unlubricated sliding friction and wear properties of a recently-developed TiZr-based alloy (Ti–20Zr–6.5Al–4V, TZ20 hereafter) were tested at elevated temperatures ranging from room temperature to 673 K. After the tribological tests, worn surface and cross-section of TZ20 alloy were analyzed to illustrate its wear behavior. The results showed that the wear rate was increased firstly with the ambient temperature, which then decreased when the temperature exceeded critical transition temperature (473 K). Also, the dominant wear mechanisms changed from adhesive wear at room temperature to abrasive wear at 473 K, and then to mild abrasive wear at highest ambient temperature of 673 K. The variations of wear behaviors could be attributed to tribo-oxide layer formed during sliding process. At ambient temperature of 673 K, the tribo-oxide layer formed on the surface was thicker and more compact, and showed more obvious protective role on tribological properties of TZ20 alloy.

An overview of very high cycle fatigue behavior of additively manufactured Ti-6Al-4V

This paper presents a brief review on the current state of knowledge of the very high cycle fatigue (VHCF) behavior of metallic parts fabricated using Additive Manufacturing (AM) processes. It has been shown that AM has significant potential to replace traditional manufacturing methods that impose geometric limitations to designs. Powder-based metallic AM methods allow for precise layer-wise processing of complex net-shape parts without the use of special tooling or molds. Among various metals commonly used in AM processes, titanium (Ti) 6Al-4V alloy is currently of great interest especially in aerospace applications that contain parts with complex geometries (i.e., turbine blades in jet engines). To safely adapt AM Ti-6Al-4V parts in these applications, their mechanical properties and fatigue behavior must be understood. Various studies have identified AM process-induced defects (i.e., entrapped gas pores, lack of fusion defects between build layers, etc.) to be the main cause of fatigue failure of AM Ti-6Al-4V parts. However, there are limited studies relating to the effects of these defects on the behavior of AM metals in the VHCF regime (beyond 107 cycles). Knowledge of the VHCF behavior of AM Ti-6Al-4V is needed for the aforementioned applications due to the high loading frequencies and long service lives required for these parts.

Effect of Microstructure on the Compressive Mechanical Properties of Ti-20Zr-6.5Al-4V Alloy

The effect of microstructure on the mechanical properties of Ti-20Zr-6.5Al-4V alloy after solution and aging treatment was investigated by compression tests. The results showed that the microstructure was consisted of a duplex phase αʺ + β structure after solution treatment. With increasing solution treatment temperature, the size of β phase grain increased and the amount of αʺ phase decreased. The ultimate compressive strength and elongation decreased with increasing solution treatment temperature, while the yield strength increased. After aging-treatment at 700 oC for 1.5 h, the microstructure consisted of a large amount of globular α phase, a little amount of fine acicular α phase and bulk β phase for the samples solution-treated at 850 oC for 0.5 h. With increasing initial solution treatment temperature, the amount of globular α phase and bulk β phase decreased, however, the amount and size of acicular α phase increased after aging treatment. The ultimate compressive strength and elongation decreased with increasing initial solution treatment temperature, whereas the yield strength firstly increased, and then slightly decreased.

Effect of Microstructure on the Compressive Mechanical Properties of Ti-20Zr-6.5Al-4V Alloy

Effect of Microstructure on the Compressive Mechanical Properties of Ti-20Zr-6.5Al-4V Alloy

Tribological Behavior and Wear Mechanism of TZ20 Titanium Alloy After Various Treatments

Abrasion is one of the most common failure forms of metals and alloys. The study of the friction and wear behavior of metals and alloys is greatly beneficial to improve their long life and safe service. The friction coefficient, weight loss, specific wear rate, and wear mechanism of Ti-20Zr-6.5Al-4V (TZ20) alloy after various treatments were investigated using a pin–disk-type wear apparatus at various normal loads. The wear results revealed that at a normal load, the friction coefficient steadily decreased, whereas the weight loss increased. By contrast, different specimens displayed distinct variation trends of specific wear rate with respect to the normal load. Further investigations indicated that the effects of hardness and toughness on the wear properties were markedly influenced by the normal load. The main characteristic of the abrasion surface gradually changed from grooves to plastic deformation as the normal load increased. The findings promote the practical application of TiZrAlV series alloys and expand wear theory.

Influence of Microstructure and Surface Roughness on Oxidation Kinetics at 500–600 °C of Ti–6Al–4V Alloy Fabricated by Additive Manufacturing

Ti--6Al--4V alloy (TA6V) is the most commonly used titanium-based alloy and is usually manufactured by casting, forging or rolling. Additive manufacturing is a new way of processing metal alloys; it is currently used for production purposes. This study focuses on the microstructure and oxidation kinetics of Ti--6Al--4V fabricated by laser beam melting. Some samples were HIP-treated (hot isostatic pressure). Ti--6Al--4V rolled and annealed was used as a reference material. Ti--6Al--4V fabricated by LBM exhibited prior $\beta$ grains elongated in the building direction with fully acicular martensite, $\alpha${\textasciiacutex}. Isothermal oxidations were performed at 500, 550 and 600Â {\textdegree}C for durations of 100, 200 and 500Â h. The oxidation kinetics followed a parabolic law. The weight gain of as-built LBM samples was twice as high as that of ground LBM samples of Ti--6Al--4V, although both sets had the same oxide layer thickness and depth of oxygen diffusion in the alloy. Ground LBM samples presented an oxidation rate close to that of conventional rolled and annealed Ti--6Al--4V alloys. It was shown the higher weight gain of LBM-produced Ti--6Al--4V samples was mainly due to their higher specific area and to the oxidation of partially melted powder on their surface.

Bioactive pedicle screws prepared by chemical and heat treatments improved biocompatibility and bone-bonding ability in canine lumbar spines.

BackgroundTitanium (Ti)-6Al-4V alloy, which is widely used in spinal instrumentation with a pedicle screw (PS) system. However, significant clinical problems, including loosening and back-out of PSs, persist. During the last decade, a novel technology that produces bioactive Ti from chemical and heat treatments has been reported that induces the spontaneous formation of a hydroxyapatite (HA) layer on the surface of Ti materials. The purpose of this study was to study the effect of bioactivation of Ti-6Al-4V PSs on the ability of HA formation in vitro and its biocompatibility and bone-bonding ability in vivo.MethodsTi-6V-4Al alloy PSs were prepared and bioactivated by NaOH-CaCl2-heat-water treatments. The HA-forming ability of bioactive PSs in simulated body fluid (SBF) was evaluated by field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDX). Six 11-month-old female beagle dogs were used for the in vivo study. Bioactive and control (without bioactivation) PSs were left and right randomly placed from L1 to L6. One and three months after surgery, lumbar spines were removed for biomechanical and histological analyses.ResultsIn vitro: The surface analysis of bioactive PSs by FE-SEM and EDX showed substantial HA deposits over the entire surface. In vivo: The mean extraction torque was significantly higher for bioactive PSs compared to controls PSs (P<0.01); there was no significant difference in pull-out strength between control and bioactive PSs. Histologically, the contact area between bone tissue and screw surface showed no significant trend to be greater in bioactive PSs compared to control PSs (P = 0.06).ConclusionsBioactive PSs prepared by chemical and heat treatments formed layers of HA on the surface of screws in vitro that improved biocompatibility and bonding ability with bone in vivo. Bioactive PSs may reduce screw loosening to overcome the obstacles confronted in spinal instrumentation surgery.

Novel Anisotropic Ductility of a High Strength Annealed Ti-20Zr-6.5Al-4V Alloy.

In this work, we investigate the mechanical properties of an annealed high strength Ti-20Zr-6.5Al-4V alloy in uniaxial tensile tests in different directions. The results show that the alloy exhibits obvious anisotropic ductility in different directions, while the tensile strength of the alloy remains almost unchanged. This phenomenon is closely related to α laths with similar orientations along the prior-β grain boundaries. These α laths significantly affect the initiation and propagation of cracks when the alloy reaches its yield limit, thereby affecting the ductility of the alloy, such that it exhibits anisotropic ductility.

Dry Sliding Wear Property of BN/Ti and BN/Ti-6Al-4V Alloy Composites Prepared by Spark Plasma Sintering

Dry Sliding Wear Property of BN/Ti and BN/Ti-6Al-4V Alloy Composites Prepared by Spark Plasma Sintering

Effects of microstructure on the mechanical properties of a high-strength Ti20Zr6.5Al4V alloy

Ageing and annealing were selected to process a forged Ti20Zr6.5Al4V (wt. %) alloy. The microstructure and mechanical properties of the processed alloy samples were investigated by scanning electron microscopy, electron backscatter diffraction, transmission electron microscopy, uniaxial tensile testing and nanoindentation. The analyses showed that the aged alloy consisted of single α-phase, whereas the annealed alloy was composed of dual (α+β) phases. The aged alloy exhibited an ultrahigh tensile strength of 1730 MPa with a low elongation of 2.3%, whereas the annealed alloy showed more balanced strength and ductility (1235 MPa and 10.8%, respectively). The effects of heat treatments on the microstructure and mechanical properties of the alloy were studied. The mechanisms of strengthening as well as the improvement of the ductility of the alloy were also discussed.

Vacuum Tribological Properties of Ti-20Zr-6.5Al-4V Alloy as Influenced by Sliding Velocities

This research studied the vacuum tribological properties of annealed Ti-20Zr-6.5Al-4V alloy sliding against AISI 440C steel at various velocities ranging from 0.39 to 1.17 m/s using a ball-on-disc tribometer equipped with a vacuum chamber. The coefficient of friction and wear volumes of the annealed Ti-20Zr-6.5Al-4V alloy were obtained. Results indicated that the coefficient of friction increased at the beginning as the sliding velocity increased to 0.78 m/s and subsequently decreased with further increase in velocity. However, the wear volume increased monotonically with sliding velocity. Scanning electron microscopy was employed to study the wear mechanisms after tribological tests. Under a normal load of 10 N, abrasive wear was predominant at various sliding velocities, whereas the sliding velocity influenced the wear mechanisms significantly when the normal load was increased to 30 N. Under higher normal load, the abrasive wear was indentified as the main wear mechanism at a lower sliding velocity of 0.39 m/s. As the sliding velocity was increased to 1.17 m/s, severer abrasive wear, delamination wear, and plastic deformation were dominant. In addition, at a sliding velocity of 1.17 m/s, the wear mechanisms were abrasive and mild adhesive wear of the TiZrAlV alloy annealed at 1273 K (1000 °C) under the load of 10 N. The mechanism changed to severe plastic deformation and delamination wear when the normal load was increased to 30 N. The three-dimensional topography of the Ti-20Zr-6.5Al-4V disc worn surface was also explored.

Friction and wear behavior of annealed Ti-20Zr-6.5Al-4V alloy sliding against 440C steel in vacuum

Tribological behavior of a recently-developed Ti-20Zr-6.5Al-4V alloy was tested in vacuum at different annealing temperatures (800°C, 900°C and 1000°C). Coefficient of friction and wear volume of the Ti-20Zr-6.5Al-4V alloy in vacuum were obtained. Scanning electron microscopy analysis was employed to determine the wear mechanism. Results show that the main wear mechanism changes from mild adhesive and severe abrasive wear at 10N loading to severe plastic deformation and delamination wear at 30N loading. A transfer layer was found on the stainless steel ball surface and the EDS results reveal that the layer originates from the Ti-20Zr-6.5Al-4V alloy. The three dimensional topography of the Ti-20Zr-6.5Al-4V worn surface was also explored.

Modelling of thrust force for worn drill bits characterised by cutting edge radius in drilling carbon fibre–reinforced plastic/Ti-6Al-4V alloy stacks

Wear rates are rapid when drilling carbon fibre–reinforced plastics/Ti-6Al-4V alloy stacks because of their distinct mechanical properties. Tool wear leads to a high thrust force, thereby reducing the quality of the drilled holes. This article develops a novel mechanistic model for carbon fibre–reinforced plastics/Ti-6Al-4V stacks, which is characterised by the cutting edge radius, to predict the variation of the thrust force when drilling with worn drill bits. Drilling experiments with varying feed rates were performed using carbide twist drill bits. The thrust force and drill edge profile were measured to calibrate and validate the presented model. The edge radius increases with both the cutting distance and number of drilled holes at varying feed rates. It was found that the growth rate of the edge radius increased with the feed rate with identical cutting distances, whereas it decreased slightly with the feed rate when the number of drilled holes was identical. Tool wear reduces the equivalent rake angle of the drill edge, resulting in higher thrust force. The maximum thrust force increases almost linearly with the edge radius of worn drills for both materials. The predicted thrust force curves are in very good agreement with the measured curves during the entire process. Average absolute errors of the maximum thrust force for carbon fibre–reinforced plastics and Ti-6Al-4V alloy are 3.24% and 1.88%, respectively.

Mechanical properties of TiB/Ti-6Al-4V alloy composites fabricated by spark plasma sintering

Mechanical properties of TiB/Ti-6Al-4V alloy composites fabricated by spark plasma sintering