Mechanical Properties Of Titanium Alloys Research Articles

Effects of magnetic field on microstructures and mechanical properties of titanium alloys in ultra-precision diamond turning

In this study, a magnetic field was superimposed in single point diamond turning (SPDT) of titanium alloys, aimed at enhancing the mechanical and microstructural properties of machined titanium alloy surface. The experimental results showed that the grain size decreased under an influence of magnetic field, showing grain refinements and reductions of grain pile up near grain boundaries on the machined surface, which grain pile up in machining of titanium alloys denotes as coarse colonies of alpha laths near grain boundary on the machined surface. Also, microhardness and ductility of the machined surfaces were enhanced simultaneously by using a magnetic field in SPDT. The study proposes a novel machining technology to enhance mechanical properties and the grain structure of machined titanium alloys in SPDT.

Modification of Mechanical Properties of High-Strength Titanium Alloys VT23 and VT23M Due to Impact-Oscillatory Loading

A simple technological method is proposed and tested experimentally, which allows for the improvement of mechanical properties in sheet two-phase high-strength titanium alloys VT23 and VT23M on the finished product (rolled metal), due to impact-oscillatory loading. Under impact-oscillatory loading and dynamic non-equilibrium processes (DNP) are realized in titanium alloys, leading to the self-organization of the structure. As a result, the mechanical properties of titanium alloys vary significantly with subsequent loading after the realization of DNP. In this study, the test modes are found, which can be used in the production conditions.

Titanium-based matrix composites reinforced with particulate, microstructure, and mechanical properties using spark plasma sintering technique: a review

The interest for lightweight and high-temperature materials for critical innovative applications is expanding in numerous modern industries. Reinforcing ceramic particles with micro/nano-scale sizes into titanium alloys is distinguished, thereby increasing the hardness and wear resistance. Alternatively, reduction in particles sizes also helps in increasing the strength, ductility, and creep resistance of the reinforced materials. Nano-ceramic has significant improvement in mechanical properties of a material, which makes it practically a good reinforcement in metal composites. Recent advancement in nanotechnology area demands innovative improvement in metal matrix composite for critical and functional applications. The effects of micro/nanomaterial dispersion in the metal matrix composite are spoken about and the formation of unexpected interfacial reaction on these properties. Powder metallurgy is a process where powder materials are being compacted or sintered in the furnace with the perspective of accomplishing higher densities. Spark plasma sintering techniques have a favorable condition over other sintering methods since it tends to decrease the sintering time with high temperatures, attaining higher densities, microstructural evolution, and the tendency to improve the mechanical properties of the material. This review focuses on the fabrication and mechanical properties of titanium alloy strengthening with micro/nano-ceramics.

Improvement of Mechanical Properties of Titanium alloy by High-Density Pulsed Electric Current

Improvement of Mechanical Properties of Titanium alloy by High-Density Pulsed Electric Current

Prediction of structure and mechanical properties of titanium alloy Ti-6Al-4V during layer formation of 3D products by additive technology of electron beam cladding

The problem of providing the necessary operational properties of titanium alloy structural elements produced by additive technologies using filler materials, in particular xBeam 3D Metal Printer electron beam welding technology, is considered. An analytical review of the existing data on the dependence of mechanical properties, grain size and microstructure of the titanium alloy Ti-6Al-4V on the cooling rate of the material has been carried out. On the base of mathematical modeling, temperature fields in the process of multilayer formation of a 3D fillet sample from Ti-6Al-4V alloy, residual stress and distortions are determined. Then macro and microstructure, as well as mechanical properties of the sample material are predicted. Comparison with the results of the experimental study of the macrostructure showed satisfactory accuracy of the modeling. The developed approach can be used to predict the macrostructure and mechanical properties of titanium alloy products obtained by additive layer-forming technologies. But there is a need to obtain experimental data for high cooling rates of material in the range of 100-700 degrees/c.

Low temperature ion nitriding titanium alloy TI-6AL-4V in the coarse grained and ultrafine-grained states

The paper presents the study of the influence of ion nitriding modes on the structure and mechanical properties of titanium alloy TI-6AL-4V in ultrafine-grained (UFG) state obtained via equal channel angular extrusion (ECAE). Optical images of a microstructure using scanning electron microscopy (SEM) were obtained. Microhardness testing by the depth of the modified layer was conducted.

Microstructure and mechanical properties of titanium alloy based composites fabricated in situ by casting and subjected to hot forging

The microstructure and mechanical properties of discontinuously reinforced Ti/TiB and Ti/(TiB + TiC) based composite materials fabricated in situ by casting were studied. High temperature α+β and near-α titanium alloys were taken as matrix materials. The composites in as-cast conditions contained randomly oriented TiB whiskers or TiB whiskers and TiC particles. Different hot forging procedures followed by heat treatment providing most creep resistant matrix conditions were applied. The produced composite materials based on Ti/TiB demonstrated appreciably higher yield stress and creep resistance in comparison with those of the matrix alloy, while retaining quite reasonable ductility. For the composite materials based on Ti/TiB and Ti/TiB + TiC, the load-bearing capacity of the TiB whiskers mainly contributed to the enhancement of strength and creep resistance, whereas the role of TiC particles was found to be negligible. At the same time, the reinforcement with TiC particles strongly reduced the room temperature ductility.

Dynamic fragmentation and spheroidization of α phase grains during hot deformation of Ti-6Al-4V alloy

AbstractDevelopment of mechanical properties of titanium alloys is usually achieved by the control of their microstructure (globular, lamellar, bimodal). Dynamic fragmentation and spheroidization of elongated α phase grains, formed from martensite laths, in the microstructure of Ti-6Al-4V alloy are considered in the paper. The effects of α phase grain spheroidization was evaluated in tensile tests over a temperature range of 800–900°C and strain rate range of 10−3–10−2s−1. Completed spheroidization of elongated α phase grains and subsequent growth of equiaxed grains for all deformation modes were found. A low value of apparent activation energy for deformation was calculated – suggesting grain boundary sliding was the main deformation mechanism. The results showed good correlation with the kinetic rate equation based on the Zener–Hollomon parameter.

Effect of annealing temperature on mechanical and antibacterial properties of Cu-bearing titanium alloy and its preliminary study of antibacterial mechanism

Cu-bearing titanium alloys are designed and studied as a novel medical metal material with antibacterial function. However, the addition of Cu would affect the mechanical properties of titanium alloy more or less, especially the ductility, despite its excellent antibacterial property. Thus, the aim of this study was to optimize the heat treatment for Cu-bearing titanium alloys in order to achieve a balance of satisfactory mechanical, antibacterial and other properties. In this study, Ti6Al4V-5 wt% Cu alloy was fabricated, and then different annealing treatments with various heating temperatures (700–910 °C) were employed on the alloy. The effects of heating temperature on microstructure evolution, mechanical properties, corrosion resistance and antibacterial performance of Ti6Al4V-5Cu alloy were systematically studied. It was found that annealing at 740 °C for Ti6Al4V-5Cu alloy showed the best comprehensive properties of high strength, excellent ductility, corrosion resistance and antibacterial performance. The Ti2Cu phases played an important role in the mechanical property and antibacterial performance for Ti6Al4V-5Cu alloy, and bacteria preferred to adhere on the α phase region, rather than the β or globule Ti2Cu region.

Research on Selective Laser Melting of Ti6Al4V: Surface Morphologies, Optimized Processing Zone, and Ductility Improvement Mechanism

The quality and mechanical properties of titanium alloy fabricated using selective laser melting (SLM) are critical to the adoption of the process which has long been impeded by the lack of uniformity in SLM-fabrication parameter optimization. In order to address this problem, laser power and scanning speed were combined into linear energy density as an independent variable, while surface morphology was defined as a metric. Based on full-factor experiments, the surface quality of SLM-fabricated titanium alloy was classified into five zones: severe over-melting zone, high-energy density nodulizing zone, smooth forming zone, low-energy density nodulizing zone, and sintering zone. The mechanism resulting in the creation of each zone was analyzed. Parameter uniformity was achieved by establishing a parameter window for each zone, and it also revealed that under smooth forming conditions, the relationship of linear energy density to the quality of the formed surface is not linear. It was also found that fabrication efficiency could be improved in the condition of the formation of a smooth surface by increasing laser power and scanning speed. In addition, maximum elongation of the SLM-fabricated titanium alloy increased when the densified parts were processed using an appropriate heat treatment, from a low value of 5.79% to 10.28%. The mechanisms of change in ductility of the alloy were thoroughly analyzed from the perspectives of surface microstructure and fracture morphology. Results indicate that after heat treatment, the microcosmic structure of the alloy was converted from acicular martensite α’ phase to a layered α+β double-phase structure, the fracture type also changed from quasi-cleavage to ductile fracture.

Titanium Alloys 2017

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Surface characteristics and biocompatibility of cranioplasty titanium implants following different surface treatments

ObjectiveSurface and mechanical properties of titanium alloys are integral for their use in restoring bone defects of skull and face regions. These properties are affected by the method of constructing and surface treatment of the titanium implant. This study aimed to investigate the effects of titanium finishing protocols on the surface morphology, hardness and biocompatibility of TiAl6V4. MethodsSquare shaped TiAl6V4 specimens (ASTM F68) (10×10×0.5mm) were divided into seven groups of different surface treatments (n=10). The treatments included mechanical polishing, sandblasting with AL2O3 (50μm), immersion in different acids, and/or electro-chemical anodization. Weight loss %; 3D micro-roughness; Knoop micro-hardness, and osteoblast cell attachment and proliferation (after 3 days) were determined for each specimen. Data was analysed using one way ANOVA and Dunett T3 post-hoc tests, and t-test (p<0.05). ResultsWeight loss % was in the range of 1.70–5.60 as mechanical polishing produced the highest weight loss, followed by sandblasting, and combined protocol of mechanical polishing and acid treatment (p<0.05). Micro-roughness values (μm) were in the range of 2.81–16.68. It was the highest for control specimens (p<0.05), and smoothest surfaces after combined mechanical polishing and acid treatment; or after electro-chemical treatment (p<0.05). Micro-hardness values (MPa) ranged 170.90–442.15 as sandblasting with/without acid treatment caused statically significantly the highest values (p<0.05) while control and mechanically polished specimens had the lowest values (p<0.05). All treatments produced equally biocompatible surfaces (p>0.05) after 1h or 3 days. Furthermore, osteoblast cell proliferation statistically significantly increased after 3days among each surface treatment (p<0.05). SignificanceDifferent finishing treatments have variable effect on cranioplasty titanium surface loss, micro-roughness and micro-hardness but constant improved biocompatibility effect. Electro-chemical treatment caused less material loss and produced biocompatible smoothest surface of comparable hardness; hence it can be suitable for cranioplasty titanium surface finishing.

Effect of deformation of constituent phases on mechanical properties of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si titanium alloy

Deformation of constituent phases determines the mechanical properties of titanium alloys. To address this relationship, the deformation of primary α (αp), secondary α plates (αs) and residual β phase (βr) in Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy was investigated based on the microstructure near fracture surface of uniaxial tensile samples. It is found that αp is elongated and αs mainly undergoes kinking deformation during tensile tests. The deformation of αp is dominated by planar slipping, the deformation of αs in colony is dominated by planar slipping and in basket weave is controlled by twin, planar slipping and dislocation tangling and the deformation of βr is controlled by dislocation tangling. In the microstructure with high volume fraction of αp (about 60%), the deformation amount of both αp and αs increases with the thickness of αs, which increases the elongation of the alloy and changes the failure modes of αp from fracture to boundary separation. In the microstructure with low volume fraction of αp (19%) and long αs, αp has large deformation amount, while αs with relative small deformation amount has large kinking region which increases the strength of the alloy. However, due to low volume fraction of αp, its contribution to the ductility of alloy is limited and thus the elongation of the alloy is relatively small.

A design of Ti-6Al-4V/ZrB2 multilayers with good thermal stability to enhance mechanical properties of titanium alloy

The inserting a ZrB2 modulation layer into TC4 (Ti-6Al-4V) film to form TC4/ZrB2 multilayers was developed to improve the performance of TC4 film. The enhanced crystallinity of ZrB2 not only enhanced mechanical properties of multilayers with the modulation ratio decreases, but also restricted the propagation of shear bands and promoted the nucleation of new shear bands, which was of help for the plasticity enhancement of TC4 layer. Moreover, the highest hardness (22.54GPa) and elastic modulus (262.25GPa) values were reached at lTC4:lZrB2 of 1:5, and the law of variation was like that simulated by the rule of mixture. The highest critical fracture load (Lmax= 57.6 mN). With the stability of the mixed interface, the multilayers also exhibited excellent thermal stability. High temperature annealing experiments proved that the multilayers maintain good microstructure and the hardness increased about 3GPa after annealed.

The influence of ruthenium on structure, corrosion and mechanical properties, and fatigue characteristics of titanium α-alloys in corrosive environment

This article discusses test results of corrosion mechanical properties and fatigue properties of deformed semifinished items (forgings and pipes) made of titanium alloys PT-7M and PT-7M with addition of ruthenium. The main mechanical properties of titanium alloys, the structure, and the ruthenium distribution in the structure are determined. Results of static three-point bending tests of specimens with crack are discussed for determination of corrosion mechanical strength and cyclic fatigue strength of forgings and pipes of these alloys in a corrosive medium.

A study of mechanical properties of titanium alloy Ti-6al-4v used as dental implant material

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; Titanium and its alloys are being extensively researched and are applied relatively in different fields of dentistry since 1970s. Its inherent advantages like high strength, ductility, low modulus of elasticity, ease of formation of oxidized surface layer, ability to retain mechanical integrity after autoclave and relatively low toxicity has led to extensive application of titanium and its alloys in implant dentistry.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; The Titanium alloy Ti-6Al-4V dental implant material used for the present study was procured from Mishra Dhatu Nigam (Midhani, Hyderabad). The mechanically polished samples were etched using Kroll’s reagent (5% hydrofluoric acid+10% nitric acid+85% water). The etched specimens were examined under optical microscope. &lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; The primary α phase being the low temperature phase, is stable and shows single phase microstructure. The size and volume fraction of the primary α and transformed β phases depend on the solution treatment temperatures and the subsequent rate of cooling.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; The success of the treatment modality relies on the knowledge of the properties required to employ them at the right situation. &lt;/p&gt;

Effect of complex combined loading mode on the fracture toughness of titanium alloys

This paper presents new experimental data concerning the effect of the complex combined loading mode on changes in the mechanical properties of titanium alloys of different classes subjected to static stretching. The complex combined loading mode consists in the application of additional pulse loads for given degrees of static pre-loading followed by quenching of titanium alloys at a temperature of liquid nitrogen under a pre-set scheme. The authors used a new method for studying the material fracture kinetics, the so-called method of complete stress-strain diagrams, to explore a full range of mechanical properties of titanium alloys subjected to the combined loading mode, including the crack resistance.

Effect of the Metallic Aging on the Microstructure and Mechanical Properties of Titanium Alloy

ABSTRACTDifferent aging heat treatments were performed in a Titanium alloy using as aging media metallic baths in comparison to typical furnace aging. As a first step, a Duplex Aging (DA) consisted of solubilization followed by quenching to room temperature after aging heat treatment in different metallic baths (Zn, Sn and Bi). A second procedure was Alternative Aging (AA) which consisted of solubilization and direct aging inside three different aforementioned baths. Microstructural aging variations begins at half hour until 30 h at 550°C inside metallic bath of Zn, Sn or Bi. Both kinds of aging promoted a microstructural variation and so on microhardness values. Microstructural analysis by Optical Microscopy showed a structural refinement after AA treatment. The highest hardness value of 375 HVN was achieved in Alternative Aging with Zn bath, which was found to be dependent on laminar α phase refining. Moreover, after AA treatment for 0.5, 1, 2, 3, 4, 10 and 30 h at 550°C in the metallic bath of Zn and Sn, the results indicated similar hardness values in different times, resulting in the fastest kinetic for Sn metallic bath at 2 h compared to that 4 h in Zn metallic bath. The observed increase in micro-hardness is not very attractive, it is recommended to use large aging times in order to stabilize final spacing of microstructural features in AA treatment.

Improvement in mechanical properties of titanium alloy (Ti-6Al-7Nb) subject to multiple laser shock peening

This paper is focused on laser shock peening (LSP) of titanium alloy (Ti-6Al-7Nb) for the first-time. This was to improve upon the artificial implant failures caused by destitute wear resistance of titanium alloys. As such, millions of patients are suffering from osteoarthritis pain, which costs billions of pounds annually to end users as they either have to undergo a complete replacement of the particular implants or a second surgery subject to implant failures. Therefore, the effect of multiple impacts on the mechanical properties and sliding wear behaviour of Ti-6Al-7Nb subjected to LSP were investigated. Ti-6Al-7Nb has the advantage of biocompatibility as the material can be applicable for orthopaedic implants. It is critical to improve the mechanical properties and wear resistance. LSP is one of the most effective methods to improve mechanical properties. Thus, in this study X-ray diffraction (XRD); Scanning Electron Microscope (SEM); surface roughness using 3-D profiling; microhardness using Vickers indentation method; and sliding wear with a tribometer were employed to measure the effect of Ti-6Al-7Nb alloy subjected LSP. It was found that the microhardness of Ti-6Al-7Nb alloy can be effectively improved from 290HV30 to 369HV30. In addition, the average the grain size was measured to be 10μm and showed a reduction of 67%. The surface roughness was increased after multiple LSP from 0.15μm to 0.52μm. However, the wear resistance was improved by 44% after multiple LSP. The findings from this work will contribute towards extending the services time of orthopaedic implants and help patients undergo reduced number of surgeries.

The Effect of Diffusion Welding Parameters on the Mechanical Properties of Titanium Alloy and Aluminum Couples

Ti-6Al-4V alloy and commercially pure aluminum, which are commonly used in aerospace, medical, and automotive industries, are bonded by diffusion welding. Different welding parameters (560, 600, and 640 °C—0, 45, and 60 min—under argon shielding) are used in this process to make the materials more applicable in the industry. Here, the effects of parameters on the strength of joints were studied. The bonded samples were subjected to microhardness and tensile tests in order to determine their interfacial strength. The hardness values were found to decrease with increasing distance from the interface on the titanium side while it remained constant on the aluminum side. Maximum tensile strength was taken from the maximum bonding temperatures of 600 and 640 °C. A morphology examination of the diffusion interfaces was carried out with scanning electron microscopy.