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Sample records for stainless steel ti-6al-4v

  1. Neutron Strain Scanning of Fibre and Diode Laser Welds in Stainless Steel and Ti6Al4 V

    Science.gov (United States)

    Voisey, K. T.; Folkes, J.; Srithorn, J.; Hughes, D. J.

    Fibre lasers provide an unprecedented combination of high beam quality, brightness and low cost. Fibre laser beams can provide an exceptionally high power density beam with a relatively large depth of focus. Compared to more established laser welding technologies such as diode laser welding, fibre laser welding produces exceptionally narrow weld beads. As with all types of welding, fibre laser welding produces residual stresses in the material forming and adjacent to the weld. The SALSA instrument at the Institut Laue Langevin (ILL) has been used to make neutron diffraction measurements for both fibre and diode laser welded stainless steel 304 and Ti6Al4 V. Clear diffraction peaks are obtained from stainless steel 304 and residual stress distributions are obtained. Little variation in residual stress distribution with welding parameters is seen. Ti6Al4 V diffraction peaks are complicated by phase transformations on cooling. Transformed beta phase peaks in Ti6Al4 V allow the extent of the heat affected zone to be determined.

  2. DIFFUSION BONDING OF TITANIUM ALLOY TI-6AL-4V AND AISI 304 STAINLESS STEEL – AN EXPERIMENTAL INVESTIGATION

    Directory of Open Access Journals (Sweden)

    M. BALASUBRAMANIAN

    2015-10-01

    Full Text Available Titanium alloy Ti-6Al-4V and AISI 304 stainless steel were diffusion bonded at various temperatures and holding times. The experimental investigation of the process parameters of the diffusion bonded coupons was carried out. Lap shear tests were performed to determine the strength of the joint, and hardness measurements were taken to understand the hardness in the diffusion region. Diffusion bonding was performed from the lower temperature to the higher temperature considering melting point of the parent material. Hardness measurement at the diffusion layer is almost equal to the parent material. Optical microscopy examination was carried out to determine the quality of the joint and XRD analysis was carried out to confirm the formation of intermetallic compounds. The highest lap shear strength of 138.3 MPa was obtained at 800˚C at 60min holding time under 5 MPa pressure.

  3. Laser surface cladding of Ti-6Al-4V on AISI 316L stainless steel for bio-implant application

    CSIR Research Space (South Africa)

    Kumar, A

    2014-01-01

    Full Text Available The present study concerns an in-depth investigation of the influence of laser surface cladding of Ti-6Al-4V on the microstructure (both the top surface, cross-section and interface), wear resistance, corrosion resistance and bio-activity of AISI...

  4. Metallic ions in organs of rats injected with metallic particles of stainless steel 316L and Ti6Al4V alloy

    Directory of Open Access Journals (Sweden)

    Silvia Helena Giertz

    2010-03-01

    Full Text Available Despite the interest in identifying systemic effects caused by the metallic particles released from long term metallic implants in the body, few works support reliable conclusions about the effects of those particles in organs. The aim of the present work is to look for damages in tissues of liver, kidney, lung and heart of rats submitted to injection of Hank's solution contained particles of Ti6Al4V alloy and Stainless Steel 316L, obtained by metal friction. The particles size ranges from 50 to 200 µm for the Ti alloy and from 100 to 500 µm for the 316L. Tissues isolated from the organs after the euthanasia were prepared and analyzed in an optical microscope and Energy Dispersive Spectrometer (EDS. Lesions caused by an inflammatory response such as strange body epithelioid granuloma and giant cells were found in some of the tissues containing yttrium and aluminum.

  5. Wear of Steel and Ti6Al4V Rollers in Vacuum

    Science.gov (United States)

    Krantz, Timothy L.; Shareef, Iqbal

    2012-01-01

    This investigation was prompted by results of a qualification test of a mechanism to be used for the James Webb Space Telescope. Post-test inspections of the qualification test article revealed some loose wear debris and wear of the steel rollers and the mating Ti6Al4V surfaces. An engineering assessment of the design and observations from the tested qualification unit suggested that roller misalignment was a controlling factor. The wear phenomena were investigated using dedicated laboratory experiments. Tests were done using a vacuum roller rig for a range of roller misalignment angles. The wear in these tests was mainly adhesive wear. The measured wear rates were highly correlated to the misalignment angle. For all tests with some roller misalignment, the steel rollers lost mass while the titanium rollers gained mass indicating strong adhesion of the steel with the titanium alloy. Inspection of the rollers revealed that the adhesive wear was a two-way process as titanium alloy was found on the steel rollers and vice versa. The qualification test unit made use of 440F steel rollers in the annealed condition. Both annealed 440F steel rollers and hardened 440C rollers were tested in the vacuum roller rig to investigate possibility to reduce wear rates and the risk of loose debris formation. The 440F and 440C rollers had differing wear behaviors with significantly lesser wear rates for the 440C. For the test condition of zero roller misalignment, the adhesive wear rates were very low, but still some loose debris was formed

  6. Dynamic behaviour of TM380 mild steel and Ti6Al4V alloy subjected to blast loading

    CSIR Research Space (South Africa)

    Shoke, Lerato

    2016-10-01

    Full Text Available and Base Metals Development Network Conference 2016, 19-20 October 2016, KwaZulu Natal, Maharani Hotel Dynamic behaviour of TM380 mild steel and Ti6Al4V alloy subjected to blast loading L. Shoke,1* K. Mutombo2, I.M. Snyman1 and T. Sono1 1... Landwards Sciences, Defence Peace Safety and Security (DPSS), 2 Material Sciences and Manufacturing (MSM), Council for Scientific and Industrial Research (CSIR), Pretoria, South Africa Lshoke@csir.co.za Abstract This paper deals...

  7. Corrosion resistance and in-vitro bioactivity of BaO containing Na2O-CaO-P2O5 phosphate glass-ceramic coating prepared on 316 L, duplex stainless steel 2205 and Ti6Al4V

    Science.gov (United States)

    Edathazhe, Akhila B.; Shashikala, H. D.

    2018-03-01

    The phosphate glass with composition 11Na2O-15BaO-29CaO-45P2O5 was coated on biomedical implant materials such as stainless steel 316 L, duplex stainless steel (DSS) 2205 and Ti6Al4V alloy by thermal enamelling method. The structural properties and composition of glass coated substrates were studied by x-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive x-ray spectroscopy (EDS) analysis. The coatings were partially crystalline in nature with porous structure and pore size varied from micro to nanometer range. The polarization curve was obtained for uncoated and coated substrates from electrochemical corrosion test which was conducted at 37 °C in Hank’s balanced salt solution (HBSS). The corrosion resistance of 316 L substrate increased after coating, whereas it decreased in case of DSS 2205 and Ti6Al4V. The XRD and SEM/EDS studies indicated the bioactive hydroxyapatite (HAp) layer formation on all the coated surfaces after electrochemical corrosion test, which improved the corrosion resistance. The observed electrochemical corrosion behavior can be explained based on protective HAp layer formation, composition and diffusion of ions on glass coated surfaces. The in-vitro bioactivity test was carried out at 37 °C in HBS solution for 14 days under static conditions for uncoated and coated substrates. pH and ion release rate measurements from the coated samples were conducted to substantiate the electrochemical corrosion test. The lower ion release rates of Na+ and Ca2+ from coated 316 L supported its higher electrochemical corrosion resistance among coated samples. Among the uncoated substrates, DSS showed higher electrochemical corrosion resistance. Amorphous calcium-phosphate (ACP) layer formation on all the coated substrates after in-vitro bioactivity test was confirmed by XRD, SEM/EDS and ion release measurements. The present work is a comparative study of corrosion resistance and bioactivity of glass coated and uncoated

  8. Additive manufacturing of metals: a brief review of the characteristic microstructures and properties of steels, Ti-6Al-4V and high-entropy alloys

    Science.gov (United States)

    Gorsse, Stéphane; Hutchinson, Christopher; Gouné, Mohamed; Banerjee, Rajarshi

    2017-01-01

    Abstract We present a brief review of the microstructures and mechanical properties of selected metallic alloys processed by additive manufacturing (AM). Three different alloys, covering a large range of technology readiness levels, are selected to illustrate particular microstructural features developed by AM and clarify the engineering paradigm relating process–microstructure–property. With Ti-6Al-4V the emphasis is placed on the formation of metallurgical defects and microstructures induced by AM and their role on mechanical properties. The effects of the large in-built dislocation density, surface roughness and build atmosphere on mechanical and damage properties are discussed using steels. The impact of rapid solidification inherent to AM on phase selection is highlighted for high-entropy alloys. Using property maps, published mechanical properties of additive manufactured alloys are graphically summarized and compared to conventionally processed counterparts. PMID:28970868

  9. Additive manufacturing of metals: a brief review of the characteristic microstructures and properties of steels, Ti-6Al-4V and high-entropy alloys.

    Science.gov (United States)

    Gorsse, Stéphane; Hutchinson, Christopher; Gouné, Mohamed; Banerjee, Rajarshi

    2017-01-01

    We present a brief review of the microstructures and mechanical properties of selected metallic alloys processed by additive manufacturing (AM). Three different alloys, covering a large range of technology readiness levels, are selected to illustrate particular microstructural features developed by AM and clarify the engineering paradigm relating process-microstructure-property. With Ti-6Al-4V the emphasis is placed on the formation of metallurgical defects and microstructures induced by AM and their role on mechanical properties. The effects of the large in-built dislocation density, surface roughness and build atmosphere on mechanical and damage properties are discussed using steels. The impact of rapid solidification inherent to AM on phase selection is highlighted for high-entropy alloys. Using property maps, published mechanical properties of additive manufactured alloys are graphically summarized and compared to conventionally processed counterparts.

  10. Shear-banding in Ti-6Al-4V

    Science.gov (United States)

    Swift, D. C.

    1994-07-01

    The yield stress of materials exhibiting work-hardening and thermal softening can reach a maximum, at which they are unstable to further strain. Deformation then localizes as shear bands. This critical strain has been calculated using parameters for the Steinberg-Guinan strength model. A simple model to predict the onset of shear-banding in the impact of flat-ended rods on plates produces results consistent with known experiments in steel/Ti-6Al-4V, using the calculated critical strain. Conduction effects can modify the critical strain by reducing the rate of thermal softening, introducing a dependence on strain rate. The magnitude of the conduction effects caused by a microstructure of spherical grains in a matrix and by solitary inclusions is estimated. Comparison with experiments indicates that the rate-dependence is consistent with conduction between the phases of the Ti-6Al-4V microstructure.

  11. Density of liquid Ti-6Al-4V

    Directory of Open Access Journals (Sweden)

    Schmon Alexander

    2017-01-01

    Full Text Available Ti-6Al-4V is due to its high strength-density ratio a commonly used alloy in aerospace industry applications. But liquid phase data are scarce as preventing contaminations of the reactive high temperature melt during the investigation process poses a challenge. The thermophysical quantity density is of special interest since it is necessary input parameter in modern numerical casting and solidification simulations. Liquid phase density of Ti-6Al-4V as function of temperature was determined employing a fast resistive pulse-heating technique based on the approach to avoid contaminations of the specimen by extremely reducing the experimental duration of the investigation process. Temperature dependent density of liquid Ti-6Al-4V was determined in a temperature range between 2050 K and 2590 K and is presented.

  12. Tribological investigations of surface treated Ti6Al4V

    International Nuclear Information System (INIS)

    Rueck, D.M.; Schminke, A.; Schmidt, H.; Soltani-Farshi, M.; Baumann, H.; Fink, U.; Richter, E.

    1998-05-01

    The tribological couple of the titanium alloy Ti6Al4V and ultrahigh molecular weight polyethylene (UHMWPE) is used for hip and knee joint prostheses. It is known that surface treatment of the titanium alloy Ti6Al4V by ion implantation of various elements can improve the wear behavior of such prostheses. The results of tribological tests, performed in Ringer solution with a ring-on-disc tester, show that oxygen in the implanted near surface region has a pronounced influence on the wear performance. Oxygen can be introduced into the surface by different mechanisms: either by direct implantation of oxygen ions or by indiffusion during the implantation of other elements like nitrogen or carbon at higher temperatures. The influence of the oxygen content in the near surface region of implanted and nonimplanted Ti6Al4V on the tribological performance is discussed in detail. (orig.)

  13. STUDY OF THERMAL BEHAVIOUR ON TITANIUM ALLOYS (TI-6AL-4V

    Directory of Open Access Journals (Sweden)

    VASUDEVAN D

    2017-08-01

    Full Text Available Titanium is 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 is called as the "space age metal" and is recognized for its high strength-to-weight ratio. Today, titanium alloys are common, readily available engineered metals that compete directly with stainless steel and Specialty steels, copper alloys, nickel based alloys and composites. Titanium alloys are needed to be heat treated in order to reduce residual stress developed during fabrication and to increase the strength. Titanium (Ti-6Al-4V alloy is an alpha, beta alloy which is solution treated at a temperature of 950 ºC to attain beta phase. This beta phase is maintained by quenching and subsequent aging to increase strength. Thermal cycling process was carried out for Ti-6Al-4V specimens using forced air cooling. Heat treated titanium alloy specimen was used to carry out various tests before and after thermal cycling, The test, like tensile properties, co-efficient of thermal expansion, Microstructure, Compression test, Vickers Hardness was examined by the following test. Coefficient of Thermal expansion was measured using Dilatometer. Tensile test was carried out at room temperature using an Instron type machine. Vickers's hardness measurement was done on the same specimen as used for the microstructural observation from near the surface to the inside specimen. Compression test was carried out at room temperature using an Instron type machine. Ti‐6Al‐4V alloy is a workhorse of titanium industry; it accounts for about 60 percent of the total titanium alloy production. The high cost of titanium makes net shape manufacturing routes very attractive. Casting is a near net shape manufacturing route that offers significant cost advantages over forgings or complicated machined parts.

  14. Determination of Process Parameters for High-Density, Ti-6Al-4V Parts Using Additive Manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-08-10

    In our earlier work, we described an approach for determining the process parameters that re- sult in high-density parts manufactured using the additive-manufacturing process of selective laser melting (SLM). Our approach, which combines simple simulations and experiments, was demon- strated using 316L stainless steel. We have also used the approach successfully for several other materials. This short note summarizes the results of our work in determining process parameters for Ti-6Al-4V using a Concept Laser M2 system.

  15. Numerical Simulation of Adiabatic Shear Bands in Ti-6Al-4V Alloy Due to Fragment Impact

    National Research Council Canada - National Science Library

    Fermen-Coker, Muege

    2004-01-01

    ... and lethality technologies for the Army's Future Combat Systems. Onset and propagation of adiabatic shear bands are investigated both experimentally and computationally by studying the ballistic impact of 20-mm steel fragments against Ti-6Al-4V plates...

  16. Excimer laser processing of Ti-6Al-4V

    International Nuclear Information System (INIS)

    Folkes, J.A.; Shibata, K.

    1994-01-01

    The effect of the excimer laser on the surface of Ti-6Al-4V is reported. Particular concentration is given to surface modification for potential materials processing applications. Results showed that: (1) there is an optimum energy for smoothing titanium; (2) at this energy density increasing the number of pulses has some, but not a significant, effect on the smoothing process; and (3) relatively smooth surfaces could be achieved at higher energy densities if the sample was processed in a helium atmosphere. Other typical surface modifications and features are also reported, including the effect of different gases on the process

  17. Microstructure and mechanical properties of direct metal laser sintered TI-6AL-4V

    Directory of Open Access Journals (Sweden)

    Becker, Thorsten Hermann

    2015-05-01

    Full Text Available Direct metal laser sintering (DMLS is a selective laser melting (SLM manufacturing process that can produce near net shape parts from metallic powders. A range of materials are suitable for SLM; they include various metals such as titanium, steel, aluminium, and cobalt-chrome alloys. This paper forms part of a research drive that aims to evaluate the material performance of the SLM-manufactured metals. It presents DMLS-produced Ti-6Al-4V, a titanium alloy often used in biomedical and aerospace applications. This paper also studies the effect of several heat treatments on the microstructure and mechanical properties of Ti-6Al-4V processed by SLM. It reports the achievable mechanical properties of the alloy, including quasi-static, crack growth behaviour, density and porosity distribution, and post-processing using various heat-treatment conditions.

  18. Material characteristic of Ti alloy (Ti-6Al-4V)

    International Nuclear Information System (INIS)

    Toyoshima, Noboru

    1997-03-01

    In regard to material characteristic of Ti alloy (Ti-6Al-4V), the following matters are provided by experiments. 1) In high temperature permeation behavior of implanted deuterium ion (0.5keV, 6.4 x 10 18 D + ions/m 2 s, ∼760deg K), the ratio of permeation flux to incident flux ranges from 3.3 x 10 -3 at 633deg K to 4.8 x 10 -3 at 753deg K. The activation energy of permeation is 0.12eV in this temperature region above 600deg K. At temperatures below 600deg K, the permeation flux of deuterium decreases drastically and the implanted ions remain in the alloy. 2) Radioactivation analysis using 14MeV fast neutron shows that Ti-6Al-4V alloy contains higher values of principal ingredients, Al, V, Fe, than that recorded at the chemical composition of Ti alloy, and also, contains impurities with Ni, Co and Mn. 3) Fraction of about 0.095wt% H 2 were absorbed in the test specimens, and tensile strength test was carried out. Under the condition of the hydrogen pressure 50 torr and temperature ∼500degC. The results show that there is no degradation in mechanical properties for absorption of with less than 0.04wt% H 2 . The tensile strength of wilding specimens have almost the same as that without wilding. Ti alloy, as a material of vacuum vessel of nuclear fusion device, must be selected to that with less impurities, particularly Co, by radioactivation analysis, and must be used under the temperature of 200-300degC, where hydrogen absorption does not make too progress. It is considered that Ti alloy can be used with less than 0.04wt% H 2 absorption in viewpoint of material mechanical strength. (author)

  19. Topographic and Electrochemical Ti6Al4V Alloy Surface Characterization in Dry and Wet Reciprocating Sliding

    Directory of Open Access Journals (Sweden)

    Z. Doni

    2013-09-01

    Full Text Available This present paper shows the behavior of functional integrity of the state Ti6Al4V alloy under reciprocating sliding wear conditions in acomparative way for two different counter materials, steel and ceramicballs in dry and corrosive environment (3.5% NaCl. The surface integrity analysis of the dry reciprocating wear tests was based on the evolution of The roughness parameters with the applied load. In the case of reciprocating wear tests in corrosive environment the surface integrity analysis was based on electrochemical parameters. Comparative analysis of the evolution of the roughness parameters with the applied load shows a higher stability of the Ti6Al4V/Al2O3 contact pair, while from the point of view of the electrochemical parameters the Tribological properties are worse than Ti6Al4V/steel ball contact pair.

  20. Characterization of laser deposited Ti6Al4V/TiC composite powders on a Ti6Al4V substrate

    CSIR Research Space (South Africa)

    Mahamood, RM

    2014-01-01

    Full Text Available This paper reports the material characterization of Ti6Al4V/TiC composite produced by laser metal deposition. The Ti6Al4V/TiC composites were deposited with a composition ratio of 50 wt.% Ti64l4V and 50 wt.% TiC. The depositions were achieved...

  1. on Ti6AL4V for biomedical applications

    Directory of Open Access Journals (Sweden)

    Juan José Pavón

    2006-01-01

    Full Text Available La fijación al tejido receptor de implantes para el reemplazo de hueso puede ser mejorada si poseen una superficie bioactiva con la capacidad de precipitar hidroxiapatita in vivo. Las aleaciones de titanio, a pesar de sus buenas propiedades mecánicas y comportamiento no-tóxico, no son bioactivas y, por tanto, no se enlazan directamente al hueso. Una de las maneras de modificar una superficie metálica bioinerte es recubriéndola con material bioactivo. En este trabajo se presenta la evaluación del comportamiento a fatiga mediante indentación hertziana (esférica de un recubrimiento de vidrio sobre Ti6Al4V. Este recubrimiento pertenece al sistema SiO2-CaO-MgO-Na2O-K2O-P2O5 y, a pesar de que puede usarse para protección contra la corrosión, ha sido específicamente diseñado para ser utilizado como capa interna de un recubrimiento bicapa bioactivo con una capa externa de bajo contenido en SiO2 para garantizar la bioactividad. Los ensayos hertzianos monotónicos permitieron obtener una secuencia de daños comenzando con tres eventos de daño tipo frágil (agrietamiento tipo anillo, cono y radial seguidos por la delaminación del recubrimiento asociada a la deformación plástica del substrato. El primer daño frágil, el agrietamiento tipo anillo, fue usado como criterio para la evaluación del agrietamiento por corrosión bajo tensión y por carga cíclica, en aire y agua destilada. Los resultados mostraron la sensibilidad del recubrimiento a la degradación bajo ambos tipos de carga, estática y cíclica, siendo esta degradación considerablemente mayor en agua destilada debido a la susceptibilidad del vidrio a la corrosión. La delaminación fue también sensible a la carga cíclica hertziana presentando dos mecanismos diferentes dependiendo de la máxima carga aplicada.

  2. Effect of friction time on mechanical and metallurgical properties of continuous drive friction welded Ti6Al4V/SUS321 joints

    International Nuclear Information System (INIS)

    Li, Peng; Li, Jinglong; Salman, Muhammad; Liang, Li; Xiong, Jiangtao; Zhang, Fusheng

    2014-01-01

    Highlights: • The effect of friction time on the microstructure and joint strength was studied. • The fit of burn-off lengths at different times yields a simple equation. • The longer friction time leads to oversized flash in Ti6Al4V side and overgrown IMCs. • An IMZ with width less than 3 μm is beneficial to make a strong metallurgical bond. • The average strength of 560 MPa is obtained and higher than ever reported results. - Abstract: Dissimilar joint of Ti6Al4V titanium alloy and SUS321 stainless steel was fabricated by continuous drive friction welding. The effect of friction time on the mechanical properties was evaluated by hardness measurement and tensile test, while the interfacial microstructure and fracture morphologies were analyzed by scanning electron microscope, energy dispersive spectroscope and X-ray Diffraction. The results show that the tensile strength increases with friction time under the experimental conditions. And the maximum average strength 560 MPa, which is 90.3% of the SUS321 base metal, is achieved at a friction time of 4 s. For all samples, studied fracture occurred along the joint interface, where intermetallic compounds like FeTi, Fe 2 Ti, Ni 3 (Al, Ti) and Fe 3 Ti 3 O and many other phases were formed among elements from the two base metals. The width of intermetallic compounds zone increases with friction time up to 3 μm, below which it is beneficial to make a strong metallurgical bond. However, the longer friction time leads to oversized flash on the Ti6Al4V side and overgrown intermetallic compounds. Finally the optimized friction time was discussed to be in the range of 2–4 s, under which the sound joint with good reproducibility can be expected

  3. Fatigue Crack Initiation and Facet Formation in Ti-6Al-4V Wires:Initiatie van vermoeiingsscheuren en facetvorming in Ti-6Al-4V draden

    OpenAIRE

    Everaerts, Joris

    2017-01-01

    In Ti-6Al-4V, fatigue cracks can nucleate internally instead of at the surface. Internal or subsurface cracks in titanium alloys are found to initiate at faceted features, which can be seen on the fracture surface after failure. These facets are fractured primary α (hcp) grains, which have broken in a very planar manner. The main purpose of this work is to study internal fracture in drawn Ti-6Al-4V wires, which has not been done before, since all published studies use forged or rolled samples...

  4. Modification of Ti6Al4V surface by diazonium compounds

    Science.gov (United States)

    Sandomierski, Mariusz; Buchwald, Tomasz; Strzemiecka, Beata; Voelkel, Adam

    2018-02-01

    Ti6Al4V alloy is the most commonly used in orthopedic industry as an endoprosthesis. Ti6Al4V exhibits good mechanical properties, except the abrasion resistance. Surface modification of Ti6Al4V in order to obtain organic layer, and then the attachment of the polymer, can allow for overcoming this problem. The aim of the work was the modification of Ti6Al4V surface by diazonium compounds: salt or cation generated in situ and examine the influence of the reducing agent - ascorbic acid, and the temperature of reaction on modification process. Moreover, the simulated body fluid was used for the assessment of the organic layer stability on Ti6Al4V surface. The evaluation of the modification was carried out using the following methods: Raman microspectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Higher temperature of modification by 4-hydroxymethylbenzenediazonium cation, provides the largest amount of organic layer on the Ti6Al4V alloy. In the case of the Ti6Al4V modified by Variamine Blue B salt, the amount of organic layer is not dependent on the reaction condition. Moreover, the ascorbic acid and the presence of TiO2 does not effect on the modification. The modified surface is completely coated with the organic layer which is stable in simulated body fluid.

  5. Mesoporous Bioactive Glass Functionalized 3D Ti-6Al-4V Scaffolds with Improved Surface Bioactivity.

    Science.gov (United States)

    Ye, Xiaotong; Leeflang, Sander; Wu, Chengtie; Chang, Jiang; Zhou, Jie; Huan, Zhiguang

    2017-10-27

    Porous Ti-6Al-4V scaffolds fabricated by means of selective laser melting (SLM), having controllable geometrical features and preferable mechanical properties, have been developed as a class of biomaterials that hold promising potential for bone repair. However, the inherent bio-inertness of the Ti-6Al-4V alloy as the matrix of the scaffolds results in a lack in the ability to stimulate bone ingrowth and regeneration. The aim of the present study was to develop a bioactive coating on the struts of SLM Ti-6Al-4V scaffolds in order to add the desired surface osteogenesis ability. Mesoporous bioactive glasses (MBGs) coating was applied on the strut surfaces of the SLM Ti-6Al-4V scaffolds through spin coating, followed by a heat treatment. It was found that the coating could maintain the characteristic mesoporous structure and chemical composition of MBG, and establish good interfacial adhesion to the Ti-6Al-4V substrate. The compressive strength and pore interconnectivity of the scaffolds were not affected by the coating. Moreover, the results obtained from in vitro cell culture experiments demonstrated that the attachment, proliferation, and differentiation of human bone marrow stromal cells (hBMSCs) on the MBG-coated Ti-6Al-4V scaffolds were improved as compared with those on the conventional bioactive glass (BG)-coated Ti-6Al-4V scaffolds and bare-metal Ti-6Al-4V scaffolds. Our results demonstrated that the MBG coating by using the spinning coating method could be an effective approach to achieving enhanced surface biofunctionalization for SLM Ti-6Al-4V scaffolds.

  6. Mesoporous Bioactive Glass Functionalized 3D Ti-6Al-4V Scaffolds with Improved Surface Bioactivity

    Directory of Open Access Journals (Sweden)

    Xiaotong Ye

    2017-10-01

    Full Text Available Porous Ti-6Al-4V scaffolds fabricated by means of selective laser melting (SLM, having controllable geometrical features and preferable mechanical properties, have been developed as a class of biomaterials that hold promising potential for bone repair. However, the inherent bio-inertness of the Ti-6Al-4V alloy as the matrix of the scaffolds results in a lack in the ability to stimulate bone ingrowth and regeneration. The aim of the present study was to develop a bioactive coating on the struts of SLM Ti-6Al-4V scaffolds in order to add the desired surface osteogenesis ability. Mesoporous bioactive glasses (MBGs coating was applied on the strut surfaces of the SLM Ti-6Al-4V scaffolds through spin coating, followed by a heat treatment. It was found that the coating could maintain the characteristic mesoporous structure and chemical composition of MBG, and establish good interfacial adhesion to the Ti-6Al-4V substrate. The compressive strength and pore interconnectivity of the scaffolds were not affected by the coating. Moreover, the results obtained from in vitro cell culture experiments demonstrated that the attachment, proliferation, and differentiation of human bone marrow stromal cells (hBMSCs on the MBG-coated Ti-6Al-4V scaffolds were improved as compared with those on the conventional bioactive glass (BG-coated Ti-6Al-4V scaffolds and bare-metal Ti-6Al-4V scaffolds. Our results demonstrated that the MBG coating by using the spinning coating method could be an effective approach to achieving enhanced surface biofunctionalization for SLM Ti-6Al-4V scaffolds.

  7. High strain rate and quasi-static tensile behaviour of Ti-6Al-4V after cyclic damage

    Directory of Open Access Journals (Sweden)

    Verleysen P.

    2012-08-01

    Full Text Available It is common that energy absorbing structural elements are subjected to a number of loading cycles before a crash event. Several studies have shown that previous fatigue can significantly influence the tensile properties of some materials, and hence the behaviour of structural elements made of them. However, when the capacity of absorbing energy of engineering materials is determined, fresh material without any fatigue damage is most often used. This study investigates the effect of fatigue damage on the dynamic tensile properties of Ti-6Al-4V in thin-sheet form. Results are completed with tests at quasi-static strain rates and observations of the fracture surfaces, and compared with results obtained from other alloys and steel grades. The experiments show that the dynamic properties of Ti-6Al-4V are not affected by a number of fatigue loading cycles high enough to significantly reduce the energy absorbing capabilities of EDM machined samples.

  8. In-vivo degradation mechanism of Ti-6Al-4V hip joints

    DEFF Research Database (Denmark)

    Lomholt, Trine Colding; Pantleon, Karen; Somers, Marcel A. J.

    2011-01-01

    In-vivo exposed Ti-6Al-4V implants were investigated to determine the degradation mechanism occurring during the articulating movements of the hip joint in the human body. Failed implants were compared to Ti-6Al-4V samples, which were tested in the laboratory for their tribocorrosion performance....... The results strongly indicate that degradation of Ti-6Al-4V has occurred with the same mechanism for both the implants and the laboratory tested samples and, hence, block-on-ring tribocorrosion testing was found to be a useful tool for mimicking the degradation occurring in the body.The degradation mechanism...

  9. Effect of cutting parameters on workpiece and tool properties during drilling of Ti-6Al-4V

    Energy Technology Data Exchange (ETDEWEB)

    Celik, Yahya Hisman; Yildiz, Hakan [Batman Univ. (Turkey). Dept. of Mechanical Engineering; Oezek, Cebeli [Firat Univ., Elazig (Turkey)

    2016-08-01

    The main aim of machining is to provide the dimensional preciseness together with surface and geometric quality of the workpiece to be manufactured within the desired limits. Today, it is quite hard to drill widely utilized Ti-6Al-4 V alloys owing to their superior features. Therefore, in this study, the effects of temperature, chip formation, thrust forces, surface roughness, burr heights, hole diameter deviations and tool wears on the drilling of Ti-6Al-4 V were investigated under dry cutting conditions with different cutting speeds and feed rates by using tungsten carbide (WC) and high speed steel (HSS) drills. Moreover, the mathematical modeling of thrust force, surface roughness, burr height and tool wear were formed using Matlab. It was found that the feed rate, cutting speed and type of drill have a major effect on the thrust forces, surface roughness, burr heights, hole diameter deviations and tool wears. Optimum results in the Ti-6Al-4 V alloy drilling process were obtained using the WC drill.

  10. A Review of the Fatigue Properties of Additively Manufactured Ti-6Al-4V

    Science.gov (United States)

    Cao, Fei; Zhang, Tiantian; Ryder, Matthew A.; Lados, Diana A.

    2018-03-01

    Various additive manufacturing (AM) technologies have been used to fabricate Ti-6Al-4V. The fatigue performance of Ti-6Al-4V varies from process to process. In this review, fatigue properties of Ti-6Al-4V alloys made by different AM technologies and post-fabrication treatments were compiled and discussed to correlate with the materials' characteristic features, primarily surface roughness and porosity. Microstructure anisotropy and porosity effects on fatigue crack growth and fatigue life are also presented and discussed. A modified Kitagawa-Takahashi diagram developed from current available fatigue data was used to quantify the influence of defects on fatigue strength. This review aims to assist in selecting/optimizing AM processes to achieve high fatigue resistance in Ti-6Al-4V, as well as provide a better understanding of the advantages and limitations of current AM techniques in producing titanium alloys.

  11. Key improvements in machining of Ti6al4v alloy: A review

    Science.gov (United States)

    Katta, Sivakoteswararao; Chaitanya, G.

    2017-07-01

    Now a days the use of ti-6al-4v alloy is high in demand in many industries like aero space, bio medical automobile, space, military etc. the production rates in the industries are not sufficient because the machiniability of ti-6al-4v is the main problem, there are several cutting tools available for metal cutting operations still there is a gap in finding the proper cutting tool material for machining of ti-6al-4v. because the properties of titanium like high heat resistant, low thermal conductivity, low weight ratio, less corrosiveness, and more many properties attracting the industrialists to use titanium as their material for their products, many researchers done the research on machininbility of ti-6al-4v by using different tool materials. but as for my literature survey there is still lot of scope is available, to find better cutting tool with techniques for machining ti-6al-4v. in this paper iam discussing the work done by various researchers on ti-6al-4v alloy with different techniques.

  12. Utilization of Electrolyte Solution in Nanotube Formation on Ti-6Al-4V Metal Alloy

    Directory of Open Access Journals (Sweden)

    Charlena

    2018-02-01

    Full Text Available Formation of nanotube morphology on the surface of Ti-6Al-4V metal did not occur homogeneously, so when it was coated with hydroxyapatite, it did not merge well. One of the factor that affected the inhomogeneously formed nanotube was the utilization of electrolyte solution. The research has been done to observe the effect of electrolyte solution in the formation of nanotube morphology on the surface of Ti-6Al-4V metal alloy. Electrolyte solution that was used was ethylene glycol, HF, and NH4F with time variation of an hour, 2 hour, and 3 hour. Formation of nanotube morphology on the surface of Ti-6Al-4V metal alloy was done using anodization process. The result showed that in HF electrolyte solution which was anodized for an hour ɑ and β phase that composed Ti-6Al-4V metal alloy was formed, meanwhile when using electrolyte solution of ethylene glycol + NH4F for 2 hours showed that there were pores that opened on Ti-6Al-4V metal alloy surface. Nanotube morphology on the surface of Ti-6Al-4V metal alloy was formed using electrolyte solution of ethylene glycol + NH4F which was anodized for 3 hours.

  13. Effect of Laser Power on Material Efficiency, Layer Height and Width of Laser Metal Deposited Ti6Al4V

    CSIR Research Space (South Africa)

    Mahamood, RM

    2012-10-01

    Full Text Available This paper reports the effect of laser power on the optimum utilization of the powder material, the layer height and the width of the laser Metal Deposited Ti6Al4V. The Ti6Al4V powder was deposited on Ti6Al4V substrate using an Nd: YAG laser...

  14. Strengthening mechanisms in Ti-6Al-4V/TiC composites

    International Nuclear Information System (INIS)

    Johnson, A.J. Wagoner; Kumar, K.S.; Briant, C.L.

    2004-01-01

    In this study, the compressive behavior of Ti-6Al-4V/TiC composites considered for ballistic applications was examined at strain rates of 0.1, 1.0, and 10 s-1. As little as 1 vol% of particulate TiC provided nearly a 25% increase in strength in Ti-6Al-4V/TiC composites over that of the monolithic Ti-6Al-4V, while subsequent additions of TiC did not provide proportional benefit. The mechanisms responsible for such a significant increase in strength were investigated for the first time in this study. Microscopy (optical, SEM, TEM) aided in identifying the possible strengthening mechanisms that are typically important to the strength of metal matrix composites. These mechanisms include grain size and subgrain size refinement and an increase in dislocation density, all of which can occur during processing. Two other important mechanisms are thermal mismatch strains and load transfer from the matrix to the particle; the contribution of these mechanisms to the strength of the composite was evaluated using the Eshelby approach. A quantitative comparison of the mechanisms listed clearly showed that none of them was responsible for the large increase in strength with only 1vol%TiC in Ti-6Al-4V. The results from this study show for the first time that carbon in solution is, by far, the most potent strengthening mechanism in the Ti-6Al-4V/TiC particulate composites

  15. Materials Characterization of Electron Beam Melted Ti-6Al-4V

    Science.gov (United States)

    Draper, Susan L.; Lerch, Bradley A.; Telesman, Jack; Martin, Richard E.; Locci, Ivan E.; Garg, Anita; Ring, Andrew J.

    2016-01-01

    An in-depth material characterization of Electron Beam Melted (EBM) Ti-6Al-4V material has been completed on samples fabricated on an ARCAM A2X EBM machine. The specimens were fabricated under eight separate builds with the material divided into two lots for material testing purposes. Hot Isostatic Pressing (HIP) was utilized to close porosity from fabrication and also served as a material heat treatment to obtain the desired microstructure. The changes in the microstructure and chemistry from the powder to pre-HIP and post-HIP material have been analyzed. Several nondestructive evaluation (NDE) techniques were utilized to characterize the samples both before and after HIP. The test matrix included tensile, high cycle fatigue, low cycle fatigue, fracture toughness, and fatigue crack growth at cryogenic, room, and elevated temperatures. The mechanical properties of the EBM Ti-6Al-4V are compared to conventional Ti-6Al-4V in the annealed condition. Fractography was performed to determine failure initiation site. The EBM Ti-6Al-4V had similar or superior mechanical properties compared to conventionally manufactured Ti-6Al-4V.

  16. Microstructure of Ti-6Al-4V produced by selective laser melting

    International Nuclear Information System (INIS)

    Simonelli, M; Tse, Y Y; Tuck, C

    2012-01-01

    Ti-6Al-4V is the most widely used titanium alloy. Manufacturing of Ti-6Al-4V components using novel additive processing techniques such as selective laser melting is of great interest. This study focuses on the microstructure characterisation of Ti-6Al-4V components produced by selective laser melting (SLM) with full (Ti-6Al-4V base plate) and partial (Ti-6Al-4V needle-shaped bed) support. The starting material, a plasma atomised powder, and the component products are studied using various microscopy techniques including optical, scanning electron and transmission electron microscopy and electron backscattered diffraction (EBSD). Powder particles are fully dense, possess a spherical shape and are composed of acicular α phase. The as-built material shows oriented acicular martensitic phase with well defined columnar grains. The morphology of martensitic phase and microstructural evolution will be discussed in relation to the SLM processing parameters employed and the different cooling rates experienced by the components.

  17. Development of porous Ti6Al4V/chitosan sponge composite scaffold for orthopedic applications

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Miao [College of Life Information Science & Instrument Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Li, Xiang, E-mail: Xiangliwj@sjtu.edu.cn [School of Mechanical Engineering, Shanghai Jiao Tong University, State Key Laboratory of Mechanical System and Vibration, Shanghai 200240 (China)

    2016-01-01

    A novel composite scaffold consisting of porous Ti6Al4V part filled with chitosan sponge was fabricated using a combination of electron beam melting and freeze-drying. The mechanical properties of porous Ti6Al4V part were examined via compressive test. The ultimate compressive strength was 85.35 ± 8.68 MPa and the compressive modulus was 2.26 ± 0.42 GPa. The microstructure of composite scaffold was characterized using scanning electron microscopy. The chitosan sponge filled in Ti6Al4V part exhibited highly porous and well-interconnected micro-pore architecture. The osteoblastic cells were seeded on scaffolds to test their seeding efficiency and biocompatibility. Significantly higher cell seeding efficiency was found on composite scaffold. The biological response of osteoblasts on composite scaffolds was superior in terms of improved cell attachment, higher proliferation, and well-spread morphology in relation to porous Ti6Al4V part. These results suggest that the Ti6Al4V/chitosan composite scaffold is potentially useful as a biomedical scaffold for orthopedic applications. - Highlights: • A novel composite scaffold with sufficient mechanical properties and favorable cell affinity environment was developed. • Significantly higher cell seeding efficiency was found on composite scaffold. • The osteoblasts on composite scaffolds showed well-spread morphology, improved cell attachment and higher proliferation.

  18. Biocompatibility and compressive properties of Ti-6Al-4V scaffolds having Mg element.

    Science.gov (United States)

    Kalantari, Seyed Mohammad; Arabi, Hossein; Mirdamadi, Shamsodin; Mirsalehi, Seyed Ali

    2015-08-01

    Porous scaffolds of Ti-6Al-4V were produced by mixing of this alloy with different amount of magnesium (Mg) powders. The mixtures were compacted in steel die by applying uniaxial pressure of 500 MPa before sintering the compacts in sealed quartz tubes at 900 °C for 2 h. Employing Archimedes׳ principle and Image Tool software, the total and open volume percentages of porosities within the scaffolds were found to be in the range of 47-64% and 41-47%, respectively. XRD results of titanium before and after sintering showed that no contamination, neither oxides nor nitrides formed during processes. Compressive properties of the scaffolds were studied using an Instron machine. The observed compressive strength and Young׳s module of the scaffolds were in the range of 72-132 MPa, and 37-47 GPa, respectively. Cell attachment and proliferation rate of MG-63 on porous samples were investigated. The results showed that proliferation rate increased with increasing Mg content. However no clear differences were observed between samples regarding cell attachment, so that bridges were observed in all cell gaps within the scaffolds. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Three-dimensional characterization of pores in Ti-6Al-4V alloy

    Directory of Open Access Journals (Sweden)

    Márcia Regina Baldissera

    2011-03-01

    Full Text Available The direct three-dimensional characterization of opaque materials through serial sectioning makes possible to visualize and better quantify a material microstructure, using classical metallographic techniques coupled with computer-aided reconstruction. Titanium alloys are used as biomaterials for bone implants because of its excellent mechanical properties, biocompatibility and enhanced corrosion resistance. The Ti-6Al-4V alloy (in wt. (% with porous microstructure permits the ingrowths of new-bone tissues improving the fixation bone/implant. This is important to understand connectivity, morphology and spatial distribution of pores in microstructure. The Ti-6Al-4V alloy compacts were produced by powder metallurgy and sintered at three distinct temperatures (1250, 1400 and 1500 °C to obtain distinct microstructures in terms of residual porosity. The visualization of the reconstructed 3D microstructure provides a qualitative and quantitative analysis of the porosity of Ti6Al4V alloy (volume fraction and pore morphology.

  20. RESIDUAL STRESS MEASUREMENTS AND STRUCTURAL INTEGRITY IMPLICATIONS FOR SELECTIVE LASER MELTED TI-6AL-4V

    Directory of Open Access Journals (Sweden)

    Knowles, C. R.

    2012-11-01

    Full Text Available Selective laser melting (SLM of Ti-6Al-4V has significant potential in the aerospace and biotechnology industries. SLM employs a focused laser beam to melt successive layers of metallic powder into complex components. This process can result in the generation of high thermally-induced residual stresses. These residual stresses, together with micro-flaws/ pores from the inherent fabrication process, may lead to premature fatigue crack initiation and propagation at relatively low cyclic stresses. The hole-drilling strain gauge method was used to evaluate residual stresses within SLM Ti-6Al-4V specimens, with the intention of understanding the associated mechanisms for the successful application of SLM Ti-6Al-4V in industry.

  1. Influence of small particles inclusion on selective laser melting of Ti-6Al-4V powder

    Science.gov (United States)

    Gong, Haijun; Dilip, J. J. S.; Yang, Li; Teng, Chong; Stucker, Brent

    2017-12-01

    The particle size distribution and powder morphology of metallic powders have an important effect on powder bed fusion based additive manufacturing processes, such as selective laser melting (SLM). The process development and parameter optimization require a fundamental understanding of the influence of powder on SLM. This study introduces a pre-alloyed titanium alloy Ti-6Al-4V powder, which has a certain amount of small particles, for SLM. The influence of small particle inclusion is investigated through microscopy of surface topography, elemental and microstructural analysis, and mechanical testing, compared to the Ti-6Al-4V powder provided by SLM machine vendor. It is found that the small particles inclusion in Ti-6Al-4V powder has a noticeable effect on extra laser energy absorption, which may develop imperfections and deteriorate the SLM fatigue performance.

  2. Tool geometry and damage mechanisms influencing CNC turning efficiency of Ti6Al4V

    Science.gov (United States)

    Suresh, Sangeeth; Hamid, Darulihsan Abdul; Yazid, M. Z. A.; Nasuha, Nurdiyanah; Ain, Siti Nurul

    2017-12-01

    Ti6Al4V or Grade 5 titanium alloy is widely used in the aerospace, medical, automotive and fabrication industries, due to its distinctive combination of mechanical and physical properties. Ti6Al4V has always been perverse during its machining, strangely due to the same mix of properties mentioned earlier. Ti6Al4V machining has resulted in shorter cutting tool life which has led to objectionable surface integrity and rapid failure of the parts machined. However, the proven functional relevance of this material has prompted extensive research in the optimization of machine parameters and cutting tool characteristics. Cutting tool geometry plays a vital role in ensuring dimensional and geometric accuracy in machined parts. In this study, an experimental investigation is actualized to optimize the nose radius and relief angles of the cutting tools and their interaction to different levels of machining parameters. Low elastic modulus and thermal conductivity of Ti6Al4V contribute to the rapid tool damage. The impact of these properties over the tool tips damage is studied. An experimental design approach is utilized in the CNC turning process of Ti6Al4V to statistically analyze and propose optimum levels of input parameters to lengthen the tool life and enhance surface characteristics of the machined parts. A greater tool nose radius with a straight flank, combined with low feed rates have resulted in a desirable surface integrity. The presence of relief angle has proven to aggravate tool damage and also dimensional instability in the CNC turning of Ti6Al4V.

  3. Direct Laser Cladding of Cobalt on Ti-6Al-4V with a Compositionally Graded Interface

    Directory of Open Access Journals (Sweden)

    Jyotsna Dutta Majumdar

    2011-01-01

    Full Text Available Direct laser cladding of cobalt on Ti-6Al-4V with and without a graded interface has been attempted using a continuous wave CO2 laser. Graded interface is developed by depositing a thin copper layer on Ti-6Al-4V substrate prior to multiple laser cladding of cobalt on it. Presence of copper interlayer was found to suppress the formation of brittle intermetallics of Ti and Co. The effect of process parameters on the microstructures, compositions, and phases of the interface was studied in details. Finally, the mechanical and electrochemical properties of the interface processed under optimum process parameters are reported.

  4. Studies of laser textured Ti-6Al-4V wettability for implants

    Science.gov (United States)

    Kumar, N.; Prakash, S.; Kumar, S.

    2016-09-01

    Wettability plays a notable role in success of any bio-implant. It influences tissue amalgamation, protein adsorption and cell attachment at the surface of an implant. Hence, wettability enhancement of the implant is a field of today's dynamic research. In this work, laser based direct melting approach was employed to generate four separate surface patterns on Ti-6Al-4V by means of nanosecond pulse fibre laser. The modification of surface morphology was assessed by means of SEM. Wettability was measured by the help of goniometer. The obtained results revealed that pulsed laser irradiation can substantially improve the biocompatibility of Ti-6AL-4V by making its surface super hydrophilic.

  5. Fatigue behavior of Ti6Al4V and 316 LVM blasted with ceramic particles of interest for medical devices.

    Science.gov (United States)

    Barriuso, S; Chao, J; Jiménez, J A; García, S; González-Carrasco, J L

    2014-02-01

    Grit blasting is used as a cost-effective method to increase the surface roughness of metallic biomaterials, as Ti6Al4V and 316 LVM, to enhance the osteointegration, fixation and stability of implants. Samples of these two alloys were blasted by using alumina and zirconia particles, yielding rough (up to Ra~8μm) and nearly smooth (up to Ra~1μm) surfaces, respectively. In this work, we investigate the sub-surface induced microstructural effects and its correlation with the mechanical properties, with special emphasis in the fatigue behavior. Blasting with zirconia particles increases the fatigue resistance whereas the opposite effect is observed using alumina ones. As in a conventional shot penning process, the use of rounded zirconia particles for blasting led to the development of residual compressive stresses at the surface layer, without zones of stress concentrators. Alumina particles are harder and have an angular shape, which confers a higher capability to abrade the surface, but also a high rate of breaking down on impact. The higher roughness and the presence of a high amount of embedded alumina particles make the blasted alloy prone to crack nucleation. Interestingly, the beneficial or detrimental role of blasting is more intense for the Ti6Al4V alloy than for the 316 steel. It is proposed that this behavior is related to their different strain hardening exponents and the higher mass fraction of particles contaminating the surface. The low value of this exponent for the Ti6Al4V alloy justifies the expected low sub-surface hardening during the severe plastic deformation, enhancing its capability to soft during cyclic loading. © 2013 Published by Elsevier Ltd.

  6. Measurement of the controlled variable during heating of Ti6Al4V for thixoforging

    Science.gov (United States)

    Gerlach, O.; Lechler, A.; Verl, A.

    2018-02-01

    Controlled heating of metal billets into the semi-solid state for thixoforming is a challenging task, mainly due to the difficulties in measuring the liquid fraction of the billet during heating. Past research primarily focused on methods measuring the liquid fraction during heating of low-melting aluminium alloys. One of these methods is time constant measurement, a contactless measurement method that uses the heating coil as a sensor. The current through the coil is used to determine the electrical time constant of the heating circuit, which itself is influenced by the specific resistance of the billet inside the coil. While previous works focused on the suitability of this method for industrial applications using aluminum alloys, this paper extends this research to the high-melting titanium alloy Ti6Al4V. This alloys shows high strength, low density and excellent corrosion resistance. It is therefore used to produce light-weight and durable components for medical and aerospace applications. Ti6Al4V is an expensive and difficult to machine alloy. Thus, it is an interesting alloy for thixoforging. However, heating of the billet into a homogeneous state of defined liquid fraction is difficult due to the poor thermal conductivity of Ti6Al4V. This paper analyses the potential of using time constant measurement for controlled heating of Ti6Al4V into the semi-solid state.

  7. Antimicrobial Activity of Nitric Oxide-Releasing Ti-6Al-4V Metal Oxide

    Science.gov (United States)

    Reger, Nina A.; Meng, Wilson S.; Gawalt, Ellen S.

    2017-01-01

    Titanium and titanium alloy materials are commonly used in joint replacements, due to the high strength of the materials. Pathogenic microorganisms can easily adhere to the surface of the metal implant, leading to an increased potential for implant failure. The surface of a titanium-aluminum-vanadium (Ti-6Al-4V) metal oxide implant material was functionalized to deliver an small antibacterial molecule, nitric oxide. S-nitroso-penicillamine, a S-nitrosothiol nitric oxide donor, was covalently immobilized on the metal oxide surface using self-assembled monolayers. Infrared spectroscopy was used to confirm the attachment of the S-nitrosothiol donor to the Ti-Al-4V surface. Attachment of S-nitroso-penicillamine resulted in a nitric oxide (NO) release of 89.6 ± 4.8 nmol/cm2 under physiological conditions. This low concentration of nitric oxide reduced Escherichia coli and Staphylococcus epidermidis growth by 41.5 ± 1.2% and 25.3 ± 0.6%, respectively. Combining the S-nitrosothiol releasing Ti-6Al-4V with tetracycline, a commonly-prescribed antibiotic, increased the effectiveness of the antibiotic by 35.4 ± 1.3%, which allows for lower doses of antibiotics to be used. A synergistic effect of ampicillin with S-nitroso-penicillamine-modified Ti-6Al-4V against S. epidermidis was not observed. The functionalized Ti-6Al-4V surface was not cytotoxic to mouse fibroblasts. PMID:28635681

  8. Mechanical properties of mill-annealed Ti6Al4 V investment cast

    CSIR Research Space (South Africa)

    Mutombo, K

    2011-07-01

    Full Text Available Ti6Al4 V alloy, produced by investment casting using yttria stabilized zirconia, was machined and then mill-annealed in vacuum furnace. The ultimate strength, yield strength and percentage elongation were largely improved compared to the same alloy...

  9. Relationships among the Microstructure, Mechanical Properties, and Fatigue Behavior in Thin Ti6Al4V

    Directory of Open Access Journals (Sweden)

    Y. Fan

    2016-01-01

    Full Text Available The microstructures of Ti6Al4V are complex and strongly affect its mechanical properties and fatigue behavior. This paper investigates the role of microstructure on mechanical and fatigue properties of thin-section Ti6Al4V sheets, with the aim of reviewing the effects of microstructure on fatigue properties where suboptimal microstructures might result following heat treatment of assemblies that may not be suited to further annealing, for example, following laser welding. Samples of Ti6Al4V sheet were subjected to a range of heat treatments, including annealing and water quenching from temperatures ranging from 650°C to 1050°C. Micrographs of these samples were inspected for microstructure, and hardness, 0.2% proof stress, elongation, and fracture strength were measured and attributed back to microstructure. Fractography was used to support the findings from microstructure and mechanical analyses. The strength ranking from high to low for the microstructures of thin Ti6Al4V sheets observed in this study is as follows: acicular α′ martensite, Widmanstätten, bimodal, and equiaxed microstructure. The fatigue strength ranking from high to low is as follows: equiaxed, bimodal, Widmanstätten, and acicular α′ martensite microstructure.

  10. Mesoporous bioactive glass functionalized 3D Ti-6Al-4V scaffolds with improved surface bioactivity

    NARCIS (Netherlands)

    Ye, Xiaotong; Leeflang, M.A.; Wu, Chengtie; Chang, Jiang; Zhou, J.; Huan, Z.

    2017-01-01

    Porous Ti-6Al-4V scaffolds fabricated by means of selective laser melting (SLM),
    having controllable geometrical features and preferable mechanical properties, have been developed as a class of biomaterials that hold promising potential for bone repair. However, the inherent bio-inertness of the

  11. Chemically milled alpha-case layer from Ti-6Al-4V alloy investment cast

    CSIR Research Space (South Africa)

    Mutombo, K

    2011-06-01

    Full Text Available The as cast Ti6Al4V, obtained after investment casting with yttria stabilized zirconia face-coat, was chemically milled using a mixture of hydrofluoric acid and nitric acid. This process removed completely the alpha-case layer. Lower hardness...

  12. Self-Consolidation Mechanism Of Porous Ti-6Al-4V Implant Prototypes Produced By Electro-Discharge-Sintering Of Spherical Ti-6Al-4V Powders

    Directory of Open Access Journals (Sweden)

    Lee W.H.

    2015-06-01

    Full Text Available Electro-Discharge-Sintering (EDS was employed to fabricate Ti-6Al-4V porous implant prototypes from atomized powders (100 – 150 μm, that were subjected to discharges of 0.75 to 2.0 kJ/0.7g-powder from 150, 300, and 450 μF capacitors. Both fully porous and porous-surfaced Ti-6Al-4V compacts with various solid core sizes were self-consolidated in less than 86 – 155 μsec. It is known that EDS can simultaneously produce the pinch pressure to squeeze and deform powder particles and the heat to weld them together. The formation of a solid core in these prototypes depends on the amounts of both the pinch pressure and heat generated during a discharge. The size of the solid core and the thickness of the porous layer can be successfully controlled by manipulating the discharge conditions such as input energy and capacitance.

  13. An empirical-statistical model for laser cladding of Ti-6Al-4V powder on Ti-6Al-4V substrate

    Science.gov (United States)

    Nabhani, Mohammad; Razavi, Reza Shoja; Barekat, Masoud

    2018-03-01

    In this article, Ti-6Al-4V powder alloy was directly deposited on Ti-6Al-4V substrate using laser cladding process. In this process, some key parameters such as laser power (P), laser scanning rate (V) and powder feeding rate (F) play important roles. Using linear regression analysis, this paper develops the empirical-statistical relation between these key parameters and geometrical characteristics of single clad tracks (i.e. clad height, clad width, penetration depth, wetting angle, and dilution) as a combined parameter (PαVβFγ). The results indicated that the clad width linearly depended on PV-1/3 and powder feeding rate had no effect on it. The dilution controlled by a combined parameter as VF-1/2 and laser power was a dispensable factor. However, laser power was the dominant factor for the clad height, penetration depth, and wetting angle so that they were proportional to PV-1F1/4, PVF-1/8, and P3/4V-1F-1/4, respectively. Based on the results of correlation coefficient (R > 0.9) and analysis of residuals, it was confirmed that these empirical-statistical relations were in good agreement with the measured values of single clad tracks. Finally, these relations led to the design of a processing map that can predict the geometrical characteristics of the single clad tracks based on the key parameters.

  14. Functionally graded Ti6Al4V and Inconel 625 by Laser Metal Deposition

    Science.gov (United States)

    Pulugurtha, Syamala R.

    The objective of the current work was to fabricate a crack-free functionally graded Ti6Al4V and Inconel 625 thin wall structure by Laser Metal Deposition (LMD). One potential application for the current material system is the ability to fabricate a functionally graded alloy that can be used in a space heat exchanger. The two alloys, Inconel 625 and Ti6Al4V are currently used for aerospace applications. They were chosen as candidates for grading because functionally grading those combines the properties of high strength/weight ratio of Ti6Al4V and high temperature oxidation resistance of Inconel 625 into one multifunctional material for the end application. However, there were challenges associated with the presence of Ni-Ti intermetallic phases (IMPs). The study focused on several critical areas such as (1) understanding microstructural evolution, (2) reducing macroscopic cracking, and (3) reducing mixing between graded layers. Finite element analysis (FEA) was performed to understand the effect of process conditions on multilayer claddings for simplified material systems such as SS316L and Inconel 625 where complex microstructures did not form. The thermo-mechanical models were developed using Abaqus(TM) (and some of them experimentally verified) to predict temperature-gradients; remelt layer depths and residual stresses. Microstructure evolution along the functionally graded Ti6Al4V and Inconel 625 was studied under different processing and grading conditions. Thermodynamic modeling using Factsage (v 6.1) was used to construct phase diagrams and predict the possible equilibrium major/minor phases (verified experimentally by XRD) that may be present along the functionally graded Ti6Al4V and Inconel 625 thin wall structures.

  15. Particle variations and effect on the microstructure and microhardness of Ti6al4 V hybrid metal matrix system

    CSIR Research Space (South Africa)

    Akinlabi, ET

    2017-01-01

    Full Text Available obtained as follow: 3.0 Ti6Al4 V, B4C and BN, 3.2 Ti6Al4 V, B4C and BN, and 3.4 Ti6Al4 V, B4C and BN systems. Laser coating experiment was done at 1400W. The influence of difference in variation of powder on the microstructure and hardness values...

  16. Tribological behavior of Ti-6Al-4V and Ti-6Al-7Nb Alloys for Total Hip Prosthesis

    Directory of Open Access Journals (Sweden)

    Mamoun Fellah

    2014-01-01

    Full Text Available The aim of the study is to evaluate the friction and wear behavior of high-strength alloys Ti-6Al-7Nb used in femoral stem and compare it with a Ti-6Al-4V alloy cylindrical bar corresponding to ISO 5832-3 part 3/01-07-199 standard. The tribological behavior was investigated by wear tests, using ball-on-disc and pin-on-disc tribometers. These tests consisted of measuring the weight loss and the friction coefficient of samples. The oscillating friction and wear tests have been carried out in ambient with oscillating tribotester in accordance with standards ISO 7148, ASTM G99-95a, and ASTM G133-95 under different conditions of normal loads (3, 6, and 10 N and sliding speeds (1, 15, and 25 mm·s−1. As counter pairs, a 100Cr6 steel ball with 10 mm in diameter was used. Results show that the two alloys had similar friction and wear performance, although their grain structures and compositions are different. Occurrence of large frictional occurred, is probably caused by formation and periodic, localized fracture of a transfer layer. Higher friction with larger fluctuation and higher wear rate was observed at the higher siding speed. The Ti-6Al-4V wear mechanism transforms from ploughing and peeling off wear at low sliding speed to plastic deformation and adhesive wear.

  17. Improved tribological behavior of boron implanted Ti-6Al-4V

    International Nuclear Information System (INIS)

    Baker, N.P.; Walter, K.C.; Nastasi, M.

    1998-03-01

    Boron implanted of Ti6Al4V has been conducted at combinations of 32 and 40 keV to supplement that done previously at 75 keV. Shallower boron depth profiles with higher B-concentrations in the Ti64 surface have been obtained by tailoring the combinations of ion energy and dose. This work used three different ion energy and dose combinations of 4 x 10 17 B-at/cm 2 at 40 keV plus 2 x 10 17 B-at/cm 2 at 32 keV, 4 x 10 17 B-at/cm 2 at 40 keV, and 4 x 10 17 B-at/cm 2 at 32 keV plus 2 x 10 17 B-at/cm 2 at 40 keV. Comparisons are made between Ti6Al4V with a shallow implanted boron depth profile, Ti6Al4V with a deeper boron depth profile and nitrogen implanted using a plasma source ion implantation process. It has been previously shown that while boron implanted Ti64 has a ∼ 30% higher surface hardness than nitrogen implanted Ti64, the N-implantation reduced the wear coefficient of Ti64 by 25--120x, while B-implantation reduced the wear coefficient by 6.5x or less. The results show that no significant improvement is made in the wear resistance of boron implanted Ti6Al4V by increasing the concentration of boron at the surface from approximately 10% to 43%. Transmission electron microscopy (TEM) and selected area diffraction (SAD) indicated the formation of crystalline TiB in the implanted surface layer. Shallower depth profiles result in reductions of the Ti6Al4V wear coefficient by 6.5x or less which is the same result obtained earlier with the deeper boron depth profile. Surface hardness of Ti6Al4V with shallower boron depth profiles was improved approximately 10% compared to the results previously acquired with deeper boron depth profiles

  18. Improving the osteointegration of Ti6Al4V by zeolite MFI coating

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yong [Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi' an, Shaanxi 710032 (China); Jiao, Yilai [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, Liaoning 110016 (China); Li, Xiaokang [Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi' an, Shaanxi 710032 (China); Guo, Zheng, E-mail: guozheng@fmmu.edu.cn [Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi' an, Shaanxi 710032 (China)

    2015-05-01

    Osteointegration is crucial for success in orthopedic implantation. In recent decades, there have been numerous studies aiming to modify titanium alloys, which are the most widely used materials in orthopedics. Zeolites are solid aluminosilicates whose application in the biomedical field has recently been explored. To this end, MFI zeolites have been developed as titanium alloy coatings and tested in vitro. Nevertheless, the effect of the MFI coating of biomaterials in vivo has not yet been addressed. The aim of the present work is to evaluate the effects of MFI-coated Ti6Al4V implants in vitro and in vivo. After surface modification, the surface was investigated using field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). No difference was observed regarding the proliferation of MC3T3-E1 cells on the Ti6Al4V (Ti) and MFI-coated Ti6Al4V (M−Ti) (p > 0.05). However, the attachment of MC3T3-E1 cells was found to be better in the M−Ti group. Additionally, ALP staining and activity assays and quantitative real-time RT-PCR indicated that MC3T3-E1 cells grown on the M−Ti displayed high levels of osteogenic differentiation markers. Moreover, Van-Gieson staining of histological sections demonstrated that the MFI coating on Ti6Al4V scaffolds significantly enhanced osteointegration and promoted bone regeneration after implantation in rabbit femoral condylar defects at 4 and 12 weeks. Therefore, this study provides a method for modifying Ti6Al4V to achieve improved osteointegration and osteogenesis. - Highlights: • Osteointegration is a crucial factor for orthopedic implants. • We coated MFI zeolite on Ti6Al4V substrates and investigated the effects in vitro and in vivo. • The MFI coating displayed good biocompatibility and promoted osteogenic differentiation in vitro. • The MFI coating promoted osteointegration and osteogenesis peri-implant in vivo.

  19. Enhanced superplastic deformation behavior of ultrafine-grained Ti-6Al-4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Saitova, L.; Hoeppel, H.W.; Goeken, M. [Department of Materials Science and Engineering, Universitaet Erlangen-Nuernberg, Erlangen (Germany); Semenova, I.; Valiev, R. [Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, Ufa (Russian Federation)

    2008-04-15

    The mechanical behavior of the Ti-6Al-4V ELI alloy in both conventional grain size (CG) and ultrafine-grained (UFG) conditions under tension and compression at elevated temperatures (500-800 C) is considered. Grain refinement by equal-channel angular pressing (ECAP) followed by multicycle extrusion was observed to result in a considerable improvement of superplastic characteristics of Ti-6Al-4V ELI alloy. The alloy exhibits a superplastic deformation behavior already at 600 C. The enhanced regime of superplasticity allows more efficient forming of parts and components. In addition, the UFG microstructure and, consequently, enhanced mechanical properties are kept after superplastic forming. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  20. HOS cell adhesion on Ti6Al4V ELI texturized by CO2 laser

    Science.gov (United States)

    Sandoval-Amador, A.; Bayona–Alvarez, Y. M.; Carreño Garcia, H.; Escobar-Rivero, P.; Y Peña-Ballesteros, D.

    2017-12-01

    In this work, the response of HOS cells on Ti6Al4V ELI textured surfaces by a CO2 laser was evaluated. The test surfaces were; smooth Ti6Al4V, used as the control, and four textured surfaces with linear geometry. These four surfaces had different separation distances between textured lines, D1 (1000 microns), D2 (750 microns), D3 (500 microns) and D4 (250 microns). Toxicity of textured surfaces was assessed by MTT and the cellular adhesion test was performed using HOS ATCC CRL 1543 line cells. This test was done after 5 days of culture in a RPMI 1640 medium supplemented with 10% fetal bovine serum and 1% antibiotics. The results showed that the linear textures present 23% toxicity after 30 days of incubation, nevertheless, the adhesion tests results are inconclusive in such conditions and therefore the effect of the line separation on the cell adhesion cannot be determined.

  1. Influence of microstructure and mean stress on the fatique behaviour of Ti-6Al-4V

    International Nuclear Information System (INIS)

    Steele, R.K.; McEvily, A.J.

    1977-01-01

    In previous fatigue studies of Ti-6Al-4V bar stock and forgings a number of findings of interest were encountered. These findings include the sub-surface initiation of fatigue cracks, a strong Bauschinger effect, cyclic softening, an influence of microstructural size on resistance to fatigue (particularly at R=0), and a dependency of cyclic-stress strain behavior on loading path. The present paper extends the work of the earlier investigations to cover a wider range of microstructures as well as cyclic loading conditions. The basic materials are forging and bar stock of the Ti-6Al-4V alloy with microstructural variations being achieved by different heat treating procedures. (Auth.)

  2. Si+ ion implantation reduces the bacterial accumulation on the Ti6Al4V surface

    International Nuclear Information System (INIS)

    Gallardo-Moreno, A M; Pacha-Olivenza, M A; Perera-Nunez, J; Gonzalez-Carrasco, J L; Gonzalez-Martin, M L

    2010-01-01

    Ti6Al4V is one of the most commonly used biomaterials in orthopedic applications due to its interesting mechanical properties and reasonable biocompatibility. Nevertheless, after the implantation, microbial adhesion to its surface can provoke severe health problems associated to the development of biofilms and subsequent infectious processes. This work shows a modification of the Ti6Al4V surface by Si+ ion implantation which reduces the bacterial accumulation under shear forces. Results have shown that the number of bacteria remaining on the surface at the end of the adhesion experiments decreased for silicon-treated surface. In general, the new surface also behaved as less adhesive under in vitro flow conditions. Since no changes are observed in the electrical characteristics between the control and implanted samples, differences are likely related to small changes observed in hydrophobicity.

  3. Evaluation of Ti-6Al-4V surface treatments for use with a polyphenylquinoxaline adhesive

    Science.gov (United States)

    Progar, Donald J.

    1987-01-01

    Three surface treatments for Ti-6Al-4V adherends were evaluated using a thermoplastic polymer monoether polyphenylquinoxaline, MEPPQ, which had been shown in previous studies to have good potential as a high temperature adhesive for aerospace applications. Initial results based on long term thermal exposure at 232 C (450 F) using the phosphate-fluoride (PF) and chromic acid anodized (CAA) treatments with MEPPQ adhesive were not encouraging. A significant improvement in strength retention and a change in failure mode (cohesive) at 232 C (450 F) was found for the SHA treated specimens compared to the PF and CAA treatments. Although an improvement in long term thermal durability was obtained with the SHA treatment of Ti-6Al-4V, an improved surface treatment with better long term durability is still required for aerospace applications.

  4. The design and production of Ti-6Al-4V ELI customized dental implants

    Science.gov (United States)

    Chahine, Gilbert; Koike, Mari; Okabe, Toru; Smith, Pauline; Kovacevic, Radovan

    2008-11-01

    This paper addresses the production of customized Ti-6Al-4V ELI dental implants via electron beam melting (EBM). The melting of Ti-6Al-4V ELI powder produces implants with great biocompatibility, fi ne mechanical performance, and a high bone ingrowth potential. The EBM technology is used to produce one-component dental implants that mimic the exact shape of the patient’s tooth, replacing the traditional, three-component, “screw-like” standardized dental implants currently used. The new generation of implants provides the possibility of simplifying pre-insertion procedures leading to faster healing time, and the potential of better and stronger osseointegration, specifi cally through incorporating lattice structure design.

  5. Effect of hydrogen on fatigue behaviour of Ti-6Al-4V

    International Nuclear Information System (INIS)

    Tasleem, M.; Haq, A.U.; Evans, W.J.; Bache, M.R.

    1995-01-01

    The fatigue behavior of hydrogen-charged titanium alloy (Ti-6Al-4V) has been studied. It is noted that hydrogen-charging to 100 ppm results in a marked decrease in the fatigue response of notched specimens. Furthermore, there is a significant increase in hardness even through the alloy microstructure is unaltered. It is argued that the hydrogen atoms act as a strengthened agent thereby restricting stress redistribution at the root of the notch and causing early crack initiation. (author)

  6. Development of a versatile procedure for the biofunctionalization of Ti-6Al-4V implants

    Energy Technology Data Exchange (ETDEWEB)

    Rezvanian, Parsa; Arroyo-Hernández, María [Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Pozuelo de Alarcón, Madrid (Spain); Departamento de Ciencia de Materiales, ETSI Caminos, Canales y Puertos, Universidad Politécnica de Madrid, 28040 Madrid (Spain); Ramos, Milagros [Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Pozuelo de Alarcón, Madrid (Spain); Daza, Rafael; Elices, Manuel; Guinea, Gustavo V. [Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Pozuelo de Alarcón, Madrid (Spain); Departamento de Ciencia de Materiales, ETSI Caminos, Canales y Puertos, Universidad Politécnica de Madrid, 28040 Madrid (Spain); Pérez-Rigueiro, José, E-mail: jperez@mater.upm.es [Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Pozuelo de Alarcón, Madrid (Spain); Departamento de Ciencia de Materiales, ETSI Caminos, Canales y Puertos, Universidad Politécnica de Madrid, 28040 Madrid (Spain)

    2016-11-30

    Highlights: • Surface of Ti-6Al-4V was functionalized by Activated Vapor Silanization (AVS). • AVS is proven to be a reliable procedure for functionalizing Ti-6Al-4V samples. • The functional layer was characterized by AFM and fluorescence microscopy. • The cytocompatibility of the functionalized samples was assessed by cell cultures. • The stability of the functional layer under physiological conditions was confirmed. - Abstract: Titanium (Ti) and titanium alloys are among the most-commonly used metallic materials for implantation in the human body for the purpose of replacing hard tissue. Although Ti and its alloys are widely used for such an aim, in implants of a long duration they exhibit some shortcomings due to the loosening of the very implant. This phenomenon is highly dependent on the interaction between the organic tissues and the surface of the implant. In this study, the authors introduce a surface treatment technique for functionalization of the surface of Ti-6Al-4V alloy with amino groups that could help to control this interaction. The functionalized layer was deposited by activated vapor silanization (AVS), which has been proven as a reliable and robust technique with other materials. The resulting biofunctional layers were characterized by atomic force microscopy and fluorescence microscopy, with the optimal conditions for the deposition of a homogeneous film with a high density of amino groups being determined. Additionally, the non-toxic nature and stability of the biofunctional layer were confirmed by cell culturing. The results show the formation of a homogeneous biofunctional amine layer on Ti-6Al-4V alloy that may be used as a platform for the subsequent covalent immobilization of proteins or other biomolecules.

  7. Characterization of Ti-6Al-4V produced via electron beam additive manufacturing

    Science.gov (United States)

    Hayes, Brian J.

    In recent years, additive manufacturing (AM) has become an increasingly promising method used for the production of structural metallic components. There are a number of reasons why AM methods are attractive, including the ability to produce complex geometries into a near-net shape and the rapid transition from design to production. Ti-6Al-4V is a titanium alloy frequently used in the aerospace industry which is receiving considerable attention as a good candidate for processing via electron beam additive manufacturing (EBAM). The Sciaky EBAM method combines a high-powered electron beam, weld-wire feedstock, and a large build chamber, enabling the production of large structural components. In order to gain wide acceptance of EBAM of Ti-6Al-4V as a viable manufacturing method, it is important to understand broadly the microstructural features that are present in large-scale depositions, including specifically: the morphology, distribution and texture of the phases present. To achieve such an understanding, stereological methods were used to populate a database quantifying key microstructural features in Ti-6Al-4V including volume fraction of phases, alpha lath width, colony scale factor, and volume fraction of basket weave type microstructure. Microstructural features unique to AM, such as elongated grains and banded structures, were also characterized. Hardness and tensile testing were conducted and the results were related to the microstructural morphology and sample orientation. Lastly, fractured surfaces and defects were investigated. The results of these activities provide insight into the process-structure-properties relationships found in EBAM processed Ti-6Al-4V.

  8. Additive manufactured Ti6Al4V scaffolds with the RF- magnetron sputter deposited hydroxyapatite coating

    International Nuclear Information System (INIS)

    Chudinova, E; Surmeneva, M; Surmenev, R; Koptioug, A; Scoglund, P

    2016-01-01

    Present paper reports on the results of surface modification of the additively manufactured porous Ti6Al4V scaffolds. Radio frequency (RF) magnetron sputtering was used to modify the surface of the alloy via deposition of the biocompatible hydroxyapatite (HA) coating. The surface morphology, chemical and phase composition of the HA-coated alloy were studied. It was revealed that RF magnetron sputtering allows preparing a homogeneous HA coating onto the entire surface of scaffolds. (paper)

  9. Increasing Efficiency of Ti-6Al-4V Machining by Cryogenic Cooling and using Nanolubricants

    Science.gov (United States)

    Krishnamurthy, Girish

    Generation of high localized cutting zone temperatures leading to dissolution wear hinders machinability of Ti alloys using uncoated carbide tools and polycrystalline diamond (PCD) tools. In addition, the thermo-plastic instability exhibited by titanium alloys promotes serrated chip formation that causes fluctuations in the cutting forces leading to chatter and severe flank wear. This work considers two methods to mitigate these problems during cutting of Ti-6Al-4V, namely, cryogenic machining to influence chip segmentation, and the use of WS2 blended metal removal fluids (MRF) to influence interface coefficient of friction (COF). Cryogenic machining of Ti-6Al-4V at 45 m/min and 0.15 mm/rev led to easier fracture of chip segments due to decrease in toughness of the material. Analyses of fracture surfaces of the chips showed that the decrease in toughness was due to increased presence of shear ridges at low temperatures. The role of COF was determined using pin-on-disk experiments. Iterative tests of Ti-6Al-4V pins sliding against uncoated WC-Co disk showed that the addition of WS2 nanoparticles to MRF are capable of decreasing the interface COF lower than that under MRF lubricated conditions alone. Orthogonal machining of Ti-6Al-4V at a cutting speed of 29.5 m/min, feed rate of 0.4 mm/rev under dry conditions generated an average cutting force of 400 N. Under MRF + WS2 lubricated conditions, the average cutting force reduced to 190 N, which was 52% lower than dry conditions. The low COF values due to the MRF + WS2 lubricant reduces the interface temperature and thus aids in machining.

  10. Osteogenic potential of a novel microarc oxidized coating formed on Ti6Al4V alloys

    Science.gov (United States)

    Wang, Yaping; Lou, Jin; Zeng, Lilan; Xiang, Junhuai; Zhang, Shufang; Wang, Jun; Xiong, Fucheng; Li, Chenglin; Zhao, Ying; Zhang, Rongfa

    2017-08-01

    In order to improve the biocompatibility, Ti6Al4V alloys are processed by micro arc oxidation (MAO) in a novel electrolyte of phytic acid, a natural organic phosphorus-containing matter. The MAO coatings were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). The cytocompatibility of Ti6A14V alloys before and after MAO were comprehensively evaluated. The results showed that the fabricated MAO coatings were composed of rutile, anatase, TiP2O7 as well as some OH- groups, exhibiting the excellent hydrophilicity and a porous structure with small micro pores. No cytotoxicity towards MC3T3-E1cells was observed in this study. In particular, MAO treated Ti6Al4V alloys presented comparable cell adhesion and proliferation as well as significantly enhanced alkaline phosphatase activity, extracellular matrix (ECM) mineralization and collagen secretion in comparison with the untreated control. The results suggest that the Ti6Al4V alloys treated by MAO in phytic acid can be used as implants for orthopaedic applications, providing a simple and practical method to widen clinical acceptance of titanium alloys.

  11. Characteristics of Resistance Spot Welded Ti6Al4V Titanium Alloy Sheets

    Directory of Open Access Journals (Sweden)

    Xinge Zhang

    2017-10-01

    Full Text Available Ti6Al4V titanium alloy is applied extensively in the aviation, aerospace, jet engine, and marine industries owing to its strength-to-weight ratio, excellent high-temperature properties and corrosion resistance. In order to extend the application range, investigations on welding characteristics of Ti6Al4V alloy using more welding methods are required. In the present study, Ti6Al4V alloy sheets were joined using resistance spot welding, and the weld nugget formation, mechanical properties (including tensile strength and hardness, and microstructure features of the resistance spot-welded joints were analyzed and evaluated. The visible indentations on the weld nugget surfaces caused by the electrode force and the surface expulsion were severe due to the high welding current. The weld nugget width at the sheets’ faying surface was mainly affected by the welding current and welding time, and the welded joint height at weld nugget center was chiefly associated with electrode force. The maximum tensile load of welded joint was up to 14.3 kN in the pullout failure mode. The hardness of the weld nugget was the highest because of the coarse acicular α′ structure, and the hardness of the heat-affected zone increased in comparison to the base metal due to the transformation of the β phase to some fine acicular α′ phase.

  12. Mechanical behavior and modelisation of Ti-6Al-4V titanium sheet under hot stamping conditions

    Science.gov (United States)

    Sirvin, Q.; Velay, V.; Bonnaire, R.; Penazzi, L.

    2017-10-01

    The Ti-6Al-4V titanium alloy is widely used for the manufacture of aeronautical and automotive parts (solid parts). In aeronautics, this alloy is employed for its excellent mechanical behavior associated with low density, outstanding corrosion resistance and good mechanical properties up to 600°C. It is especially used for the manufacture of fuselage frames, on the pylon for carrying out the primary structure (machining forged blocks) and the secondary structure in sheet form. In this last case, the sheet metal forming can be done through various methods: at room temperature by drawing operation, at very high temperature (≃900°C) by superplastic forming (SPF) and at intermediate temperature (≥750°C) by hot forming (HF). In order to reduce production costs and environmental troubles, the cycle times reduction associated with a decrease of temperature levels are relevant. This study focuses on the behavior modelling of Ti-6Al-4V alloy at temperatures above room temperature to obtained greater formability and below SPF condition to reduce tools workshop and energy costs. The displacement field measurement obtained by Digital Image Correlation (DIC) is based on innovative surface preparation pattern adapted to high temperature exposures. Different material parameters are identified to define a model able to predict the mechanical behavior of Ti-6Al-4V alloy under hot stamping conditions. The hardening plastic model identified is introduced in FEM to simulate an omega shape forming operation.

  13. Tribocorrosion Study of Ordinary and Laser-Melted Ti6Al4V Alloy

    Directory of Open Access Journals (Sweden)

    Danillo P. Silva

    2016-10-01

    Full Text Available Titanium alloys are used in biomedical implants, as well as in other applications, due to the excellent combination of corrosion resistance and mechanical properties. However, the tribocorrosion resistance of titanium alloy is normally not satisfactory. Therefore, surface modification is a way to improve this specific performance. In the present paper, laser surface-modified samples were tested in corrosion and pin-on-disk tribocorrosion testing in 0.90% NaCl under an average Hertzian pressure of 410 MPa against an alumina sphere. Laser-modified samples of Ti6Al4V were compared with ordinary Ti6Al4V alloy. Electrochemical impedance showed higher modulus for laser-treated samples than for ordinary Ti6Al4V ones. Moreover, atomic force microscopy revealed that laser-treated surfaces presented less wear than ordinary alloy for the initial exposure. For a further exposure to wear, i.e., when the wear depth is beyond the initial laser-affected layer, both materials showed similar corrosion behavior. Microstructure analysis and finite element method simulations revealed that the different behavior between the initial and the extensive rubbing was related to a fine martensite-rich external layer developed on the irradiated surface of the fusion zone.

  14. The machinability of cast titanium and Ti-6Al-4V.

    Science.gov (United States)

    Ohkubo, C; Watanabe, I; Ford, J P; Nakajima, H; Hosoi, T; Okabe, T

    2000-02-01

    This study investigated the machinability (ease of metal removal) of commercially pure (CP) titanium and Ti-6Al-4V alloy. Both CP Ti and Ti-6Al-4V were cast into magnesia molds. Two types of specimens (with alpha-case and without alpha-case) were made for CP Ti and Ti-6Al-4V. Machinability (n = 5) was evaluated as volume loss (mm3) by cutting/grinding the 3.0 mm surface using fissure burs and silicon carbide (SiC) under two machining conditions: (1) two machining forces (100 or 300 gf) at two rotational speeds (15000 or 30000 rpm) for 1 min, and (2) constant machining force of 100 gf and rotational speed of 15000 rpm for 1, 2, 5, 10, and 30 min. As controls, conventionally cast Co-Cr and Type IV gold alloys were evaluated in the same manner as the titanium. When fissure burs were used, there was a significant difference in the machinability between CP titanium with alpha-case and without alpha-case. On the other hand, there was no appreciable difference in the amount of metal removed for each tested metal when using the SiC points.

  15. Corrosion of Ti6Al4V pins produced by direct metal laser sintering

    Energy Technology Data Exchange (ETDEWEB)

    Damborenea, J.J. de, E-mail: jdambo@cenim.csic.es [Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avenida Gregorio del Amo, 8, E-28040 Madrid (Spain); Arenas, M.A. [Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avenida Gregorio del Amo, 8, E-28040 Madrid (Spain); Larosa, Maria Aparecida; Jardini, André Luiz [National Institute of Biofabrication (INCT-BIOFABRIS), State of University of Campinas (UNICAMP), Campinas (Brazil); School of Chemical Engineering, State of University of Campinas (UNICAMP), Campinas (Brazil); Carvalho Zavaglia, Cecília Amélia de [National Institute of Biofabrication (INCT-BIOFABRIS), State of University of Campinas (UNICAMP), Campinas (Brazil); Faculty of Mechanical Engineering, State of University of Campinas (UNICAMP), Campinas (Brazil); Conde, A. [Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avenida Gregorio del Amo, 8, E-28040 Madrid (Spain)

    2017-01-30

    Highlights: • Pins of Ti6Al4V have been produced by DMLS technique. • Corrosion behavior of pins is similar to Ti6Al4V commercial Kirschner wires. • Formation of voluminous white oxide can appear at potentials higher than 2.4 V. • Defects originated during processing may cause this unusual behavior. - Abstract: Direct Metal Laser Sintering (DMLS) technique allows the manufacturing a wide variety of medical devices for any type of prosthetic surgery (HIP, dental, cranial, maxillofacial) as well as for internal fixation devices (K-Wires or Steinmann Pins). There are a large number of research studies on DMLS, including microstructural characterization, mechanical properties and those based on production quality assurance but the influence of porosity in the corrosion behavior of these materials not been sufficiently considered. In the present paper, surgical pins of Ti6Al4V have been produced by DMLS. After testing in a phosphate buffered saline solution, the surface of the titanium alloy appeared locally covered by a voluminous white oxide. This unexpected behavior was presumably due to the existence of internal defects in the pins as result of the manufacturing process. The importance of these defects—that might act as crevice nucleation sites- has been revealed by electrochemical techniques and confirmed by computed tomography.

  16. Heat treatment of TI-6AL-4V produced by lasercusing

    Directory of Open Access Journals (Sweden)

    Becker, Thorsten

    2015-08-01

    Full Text Available LaserCUSING® is a selective laser melting (SLM process that is capable of manufacturing parts by melting powder with heat input from a laser beam. LaserCUSING demonstrates potential for producing the intricate geometries specifically required for biomedical implants and aerospace applications. One main limitation to this form of rapid prototyping is the lack of published studies on the material performance of the resulting material. Studies of the material’s performance are often complicated by dependence on several factors, including starting powder properties, laser parameters, and post-processing heat treatments. This study aims to investigate the mechanical properties of LaserCUSING-produced Ti-6Al-4V and its performance relative to the conventional wrought counterpart. A combination of conventional and LaserCUSING-tailored heat treatments is performed. The resulting microstructures are studied and linked to the properties obtained from hardness tests. The findings highlight that LaserCused Ti-6Al-4V is competitive with traditional materials, provided that optimal parameters are chosen and parts are subject to tailored post-processing. In the as-built condition, LaserCused Ti-6Al-4V displays superior strength and hardness as a result of a martensitic microstructure, and a poorer performance in ductility. However, the material performance can be improved using tailored heat treatments. Careful consideration must be given to suitable post-processing before application in critical components in the aerospace or biomedical industry can occur

  17. High-pressure coolant effect on the surface integrity of machining titanium alloy Ti-6Al-4V: a review

    Science.gov (United States)

    Liu, Wentao; Liu, Zhanqiang

    2018-03-01

    Machinability improvement of titanium alloy Ti-6Al-4V is a challenging work in academic and industrial applications owing to its low thermal conductivity, low elasticity modulus and high chemical affinity at high temperatures. Surface integrity of titanium alloys Ti-6Al-4V is prominent in estimating the quality of machined components. The surface topography (surface defects and surface roughness) and the residual stress induced by machining Ti-6Al-4V occupy pivotal roles for the sustainability of Ti-6Al-4V components. High-pressure coolant (HPC) is a potential choice in meeting the requirements for the manufacture and application of Ti-6Al-4V. This paper reviews the progress towards the improvements of Ti-6Al4V surface integrity under HPC. Various researches of surface integrity characteristics have been reported. In particularly, surface roughness, surface defects, residual stress as well as work hardening are investigated in order to evaluate the machined surface qualities. Several coolant parameters (including coolant type, coolant pressure and the injection position) deserve investigating to provide the guidance for a satisfied machined surface. The review also provides a clear roadmap for applications of HPC in machining Ti-6Al4V. Experimental studies and analysis are reviewed to better understand the surface integrity under HPC machining process. A distinct discussion has been presented regarding the limitations and highlights of the prospective for machining Ti-6Al4V under HPC.

  18. A comparison of the surface characteristics and ion release of Ti6Al4V and heat-treated Ti6Al4V.

    Science.gov (United States)

    Lee, T M; Chang, E; Yang, C Y

    2000-06-15

    This work seeks to investigate the nanosurface characteristics and ion release for a Ti6Al4V alloy prepared by various methods (as received and heat treated at 1300 degrees C for 2 h) with three different passivation treatments (34% nitric acid passivation, 400 degrees C heating in air, and aging in 100 degrees C deionized water). The surface and nanosurface composition are not related to the surface passivation treatments and experimental materials as evaluated by energy dispersive spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses. After passivation and autoclaving treatments, the specimens were immersed in 8.0 mM ethylenediaminetetraacetic acid (EDTA) in Hank's solution and maintained at 37 degrees C for periods of time up to 16 days. The 400 degrees C treated specimens exhibit a substantial reduction in constituent release, which may be attributed to the thicker thickness and rutile structure of the surface oxides. After soaking in Hank's-EDTA solution, a significant time-related decrease in constituent release rate is observed for all kinds of specimens throughout the 0-16 day experimental period. The thicker oxides may be a factor in the improved dissolution resistance. Upon immersion, nonelemental Ca and P are both detected on the surfaces of all kinds of specimens by XPS analysis, and this could be explained by the existence of two types of hydroxyl groups (acidic and basic OH groups) on the oxide surface of the specimens. Copyright 2000 John Wiley & Sons, Inc.

  19. Microstructures and mechanical properties of electron beam-rapid manufactured Ti-6Al-4V biomedical prototypes compared to wrought Ti-6Al-4V

    International Nuclear Information System (INIS)

    Murr, L.E.; Esquivel, E.V.; Quinones, S.A.; Gaytan, S.M.; Lopez, M.I.; Martinez, E.Y.; Medina, F.; Hernandez, D.H.; Martinez, E.; Martinez, J.L.; Stafford, S.W.; Brown, D.K.; Hoppe, T.; Meyers, W.; Lindhe, U.; Wicker, R.B.

    2009-01-01

    This study represents an exploratory characterization and comparison of electron-beam melted (EBM) or rapid manufacturing (RM) of Ti-6Al-4V components (from nominal 30 μm diameter powder) with wrought products. Acicular α and associated β microstructures observed by optical metallography and electron microscopy (SEM and TEM) are compared along with corresponding tensile test and hardness data; including the initial powder particles where the Vickers microindentation hardness averaged 5.0 GPa in comparison with the fully dense, EB manufactured product with an average microindentation hardness ranging from 3.6 to 3.9 GPa. This compared with wrought products where the Vickers microindentation hardness averaged 4.0 GPa. Values of UTS for the EBM samples averaged 1.18 GPa for elongations ranging from 16 to 25%. Biomaterials/biomedical applications of EBM prototypes in direct prosthesis or implant manufacturing from CT or MRI data are discussed in the context of this work, especially prospects for tailoring physical properties through EB control to achieve customized and optimized implant and prosthetic products direct from CT-scans

  20. Adsorption of human fibrinogen and albumin onto hydrophobic and hydrophilic Ti6Al4V powder

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Sánchez, Jesús; Gallardo-Moreno, Amparo M.; Bruque, José M.; González-Martín, M. Luisa, E-mail: mlglez@unex.es

    2016-07-15

    Adsorption of proteins on solid surfaces has been widely studied because of its importance in various biotechnological, medical and technical applications, such as medical implants or biosensors. One of the main problems is the adsorption-induced conformational changes because they often modify the biological activity of the proteins, which is believed to be a key factor on the subsequent cellular adhesion. The aim of this work is the study of the adsorption of human fibrinogen (Fg) and human serum albumin (HSA) onto Ti6Al4V particles, commercially available on different size, that are used to elaborate scaffolds to provide structural support to cell proliferation, promoting tissue development and bone regeneration among others. The study was done through the analysis of the adsorption isotherms and the electrical characterization of surfaces after adsorption in terms of the zeta potential (ζ). From this analysis it seems that Fg adsorbs preferentially vertically oriented (end-on) and HSA moves sequentially over the surface of the Ti6Al4V particles through dimmer formation, allowing adsorption progress over this initial bilayer. The zeta potential values of both proteins remain constant when the monolayer is formed. The study also extends the analysis of both adsorption behaviour and ζ potential characterization factors to the influence of the substrate hydrophobicity as this property can be modified for the Ti6Al4V by irradiating it with ultraviolet light (UV-C) without changes on its chemical composition [1,2]. Differences at low protein concentrations were found for both isotherms and zeta-potential values.

  1. Osteogenic potential of a novel microarc oxidized coating formed on Ti6Al4V alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yaping [School of Materials and Electromechanics, Jiangxi Science and Technology Normal University, Nanchang 330038 (China); Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China); Lou, Jin [School of Materials and Electromechanics, Jiangxi Science and Technology Normal University, Nanchang 330038 (China); Zeng, Lilan [Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China); Xiang, Junhuai; Zhang, Shufang; Wang, Jun; Xiong, Fucheng; Li, Chenglin [School of Materials and Electromechanics, Jiangxi Science and Technology Normal University, Nanchang 330038 (China); Zhao, Ying, E-mail: ying.zhao@siat.ac.cn [Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China); Zhang, Rongfa, E-mail: rfzhang-10@163.com [School of Materials and Electromechanics, Jiangxi Science and Technology Normal University, Nanchang 330038 (China)

    2017-08-01

    Highlights: • Phytic acid is used as the MAO electrolyte of titanium alloys. • MAO coatings are composed of rutile, anatase, TiP{sub 2}O{sub 7} and some OH{sup −} groups. • The MAO samples present excellent in vitro cytocompatibility. - Abstract: In order to improve the biocompatibility, Ti6Al4V alloys are processed by micro arc oxidation (MAO) in a novel electrolyte of phytic acid, a natural organic phosphorus-containing matter. The MAO coatings were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). The cytocompatibility of Ti6A14V alloys before and after MAO were comprehensively evaluated. The results showed that the fabricated MAO coatings were composed of rutile, anatase, TiP{sub 2}O{sub 7} as well as some OH{sup −} groups, exhibiting the excellent hydrophilicity and a porous structure with small micro pores. No cytotoxicity towards MC3T3-E1cells was observed in this study. In particular, MAO treated Ti6Al4V alloys presented comparable cell adhesion and proliferation as well as significantly enhanced alkaline phosphatase activity, extracellular matrix (ECM) mineralization and collagen secretion in comparison with the untreated control. The results suggest that the Ti6Al4V alloys treated by MAO in phytic acid can be used as implants for orthopaedic applications, providing a simple and practical method to widen clinical acceptance of titanium alloys.

  2. Macrophages adhesion rate on Ti-6Al-4V substrates: polishing and DLC coating effects

    Directory of Open Access Journals (Sweden)

    Everton Diniz dos Santos

    Full Text Available Abstract Introduction Various works have shown that diamond-like carbon (DLC coatings are able to improve the cells adhesion on prosthesis material and also cause protection against the physical wear. On the other hand there are reports about the effect of substrate polishing, in evidence of that roughness can enhance cell adhesion. In order to compare and quantify the joint effects of both factors, i.e, polishing and DLC coating, a commonly prosthesis material, the Ti-6Al-4V alloy, was used as raw material for substrates in our studies of macrophage cell adhesion rate on rough and polished samples, coated and uncoated with DLC. Methods The films were produced by PECVD technique on Ti-6Al-4V substrates and characterized by optical profilometry, scanning electron microscopy and Raman spectroscopy. The amount of cells was measured by particle analysis in IMAGE J software. Cytotoxicity tests were also carried out to infer the biocompatibility of the samples. Results The results showed that higher the surface roughness of the alloy, higher are the cells fixing on the samples surface, moreover group of samples with DLC favored the cell adhesion more than their respective uncoated groups. The cytotoxity tests confirmed that all samples were biocompatible independently of being polished or coated with DLC. Conclusion From the observed results, it was found that the rougher substrate coated with DLC showed a higher cell adhesion than the polished samples, either coated or uncoated with the film. It is concluded that the roughness of the Ti-6Al-4V alloy and the DLC coating act complementary to enhance cell adhesion.

  3. Characterization of the direct metal laser sintered Ti6Al4V Components

    CSIR Research Space (South Africa)

    Chauke, L

    2013-09-01

    Full Text Available using the DMLS method. Emphasis was made on internal and external flaws generated during layer by layer building 2. Experimental procedure Ti6Al4V dog-borne sample produced by DMLS powder bed method is schematically shown in Figure 1. The EONSINT M...270 equipment [10] was used for the production of dog-bone samples. The sample gauge length, breath and width are given in Figure 1. Tensile properties, hardness profile, microstructure analysis of the as received and heat treated samples were...

  4. Plastic flow instability and multiple necking of Ti-6Al-4V during superplastic flow

    International Nuclear Information System (INIS)

    Arieli, A.; Rosen, A.

    1976-01-01

    Stress-strain curves obtained at constant crosshead velocity tensile tests of Ti--6Al--4V sheets at different temperatures show different behavior. The flow stress does not decrease continuously, suggesting that necking occurs at various locations along the gauge length. Metallography showed regions of small, diffused necks. It is suggested that the superplasticity is related to the resistance to neck growth rather than the resistance to neck formation, and that neck formation/growth is controlled by the mutual action of strain hardening and strain rate sensitivity

  5. Structure of Ti-6Al-4V nanostructured titanium alloy joint obtained by resistance spot welding

    Science.gov (United States)

    Klimenov, V. A.; Kurgan, K. A.; Chumaevskii, A. V.; Klopotov, A. A.; Gnyusov, S. F.

    2016-01-01

    The structure of weld joints of the titanium alloy Ti-6Al-4V in the initial ultrafine-grained state, obtained by resistance spot welding, is studied using the optical and scanning electron microscopy method and the X-ray structure analysis. The carried out studies show the relationship of the metal structure in the weld zone with main joint zones. The structure in the core zone and the heat affected zone is represented by finely dispersed grains of needle-shaped martensite, differently oriented in these zones. The change in the microhardness in the longitudinal section of the weld joint clearly correlates with structural changes during welding.

  6. The transient creep of vapor deposited Ti-6Al-4V

    International Nuclear Information System (INIS)

    Warren, J.; Wadley, H.N.G.

    1996-01-01

    Titanium matrix composites can be synthesized by the consolidation of ceramic fibers (for example, alumina and silicon carbide monofilaments) coated with titanium alloy deposited on the fiber by physical vapor deposition (PVD). Consolidation involves deformation of the matrix coating by both transient and steady-state creep. In a recent paper the mechanisms responsible for steady-state creep in PVD Ti-6Al-4V, between 600 and 900 C, were determined. The analysis of the data first presented has been extended here to consider the transient creep behavior of the material and identify an analogous constitutive law for use in simulating the transient creep contribution to consolidation

  7. Correlation of microstructure and fatigue crack growth resistance in Ti-6Al-4V alloy

    CSIR Research Space (South Africa)

    Masete, Stephen

    2016-10-01

    Full Text Available of Microstructure and Fatigue Crack Growth Resistance in Ti-6Al-4V alloy Stephen Masete,1,2* Kalenda Mutombo1,2*, Roelf Mostert2, Charles Siyasiya2 and Waldo Stumpf2 1MSM/Light Metals, Council for Scientific and Industrial Research, (CSIR), Pretoria..., South Africa 2Department of Materials Science and Metallurgical Engineering, University of Pretoria, Pretoria, South Africa *Email: smasete@csir.co.za, kmutombo@csir.co.za The effect of the microstructure on fatigue crack growth resistance...

  8. Environmentally clean micromilling of electron beam melted Ti6Al4V

    DEFF Research Database (Denmark)

    Bruschi, S.; Tristo, G.; Rysava, Z.

    2016-01-01

    The paper is aimed at evaluating the performances of Minimum Quantity Lubrication (MQL), dry cutting and cryogenic cooling when applied to the micro-milling of Ti6Al4V titanium alloy samples obtained by Additive Manufacturing (AM) using the Electron Beam Melting (EBM) technology. The micro...... alterations, in order to prove the impact of clean cutting conditions when applied to micro-machining of a AM titanium alloy of biomedical interest. It is shown that dry cutting assures the same performances of MQL, representing then the most suitable option to decrease the environmental impact...

  9. Microstructural Evolution of Ti-6Al-4V during High Strain Rate Conditions of Metal Cutting

    Science.gov (United States)

    Dong, Lei; Schneider, Judy

    2009-01-01

    The microstructural evolution following metal cutting was investigated within the metal chips of Ti-6Al-4V. Metal cutting was used to impose a high strain rate on the order of approx.10(exp 5)/s within the primary shear zone as the metal was removed from the workpiece. The initial microstructure of the parent material (PM) was composed of a bi-modal microstructure with coarse prior grains and equiaxed primary located at the boundaries. After metal cutting, the microstructure of the metal chips showed coarsening of the equiaxed primary grains and lamellar. These metallographic findings suggest that the metal chips experienced high temperatures which remained below the transus temperature.

  10. Structure of Ti-6Al-4V nanostructured titanium alloy joint obtained by resistance spot welding

    Energy Technology Data Exchange (ETDEWEB)

    Klimenov, V. A., E-mail: klimenov@tpu.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation); Kurgan, K. A., E-mail: kirill-k2.777@mail.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); Chumaevskii, A. V., E-mail: tch7av@gmail.com [Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, 2/4 Akademicheskii pr., Tomsk, 634021 (Russian Federation); Klopotov, A. A., E-mail: klopotovaa@tsuab.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050 (Russian Federation); Gnyusov, S. F., E-mail: gnusov@rambler.ru [National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation)

    2016-01-15

    The structure of weld joints of the titanium alloy Ti-6Al-4V in the initial ultrafine-grained state, obtained by resistance spot welding, is studied using the optical and scanning electron microscopy method and the X-ray structure analysis. The carried out studies show the relationship of the metal structure in the weld zone with main joint zones. The structure in the core zone and the heat affected zone is represented by finely dispersed grains of needle-shaped martensite, differently oriented in these zones. The change in the microhardness in the longitudinal section of the weld joint clearly correlates with structural changes during welding.

  11. Influence of trace boron addition on the directional solidification characteristics of Ti-6Al-4V

    International Nuclear Information System (INIS)

    Srinivasan, Raghavan; Tamirisakandala, Sesh

    2010-01-01

    Trace boron addition to several titanium alloys results in a reduction in the as-cast grain size by an order of magnitude. TiB needles are observed along the prior beta grain boundaries and not the grain interior in these alloys, indicating that TiB needles are not sites for the heterogeneous nucleation of beta grains. This study seeks to understand the influence of the growth rate R on microstructure evolution and grain refinement in Ti-6Al-4V-0.1B alloy using directional solidification experiments and microstructural characterization.

  12. An Assessment of Subsurface Residual Stress Analysis in SLM Ti-6Al-4V

    Directory of Open Access Journals (Sweden)

    Tatiana Mishurova

    2017-03-01

    Full Text Available Ti-6Al-4V bridges were additively fabricated by selective laser melting (SLM under different scanning speed conditions, to compare the effect of process energy density on the residual stress state. Subsurface lattice strain characterization was conducted by means of synchrotron diffraction in energy dispersive mode. High tensile strain gradients were found at the frontal surface for samples in an as-built condition. The geometry of the samples promotes increasing strains towards the pillar of the bridges. We observed that the higher the laser energy density during fabrication, the lower the lattice strains. A relief of lattice strains takes place after heat treatment.

  13. Laser Surface Preparation for Adhesive Bonding of Ti-6Al-4V

    Science.gov (United States)

    Belcher, Marcus A.; List, Martina S.; Wohl, Christopher J.; Ghose, Sayata; Watson, Kent A.; Hopkins, John W.; Connell, John W.

    2010-01-01

    Adhesively bonded structures are potentially lighter in weight than mechanically fastened ones, but existing surface treatments are often considered unreliable. Two main problems in achieving reproducible and durable adhesive bonds are surface contamination and variability in standard surface preparation techniques. In this work three surface pretreatments were compared: laser etching with and without grit blasting and conventional Pasa-Jell treatment. Ti-6Al-4V surfaces were characterized by contact angle goniometry, optical microscopy, and X-ray photoelectron spectroscopy (XPS). Laser -etching was found to produce clean surfaces with precisely controlled surface topographies and PETI-5 lap shear strengths and durabilities were equivalent to those produced with Pasa-Jell.

  14. Stress-Corrosion Cracking and Fatigue Crack Growth Behavior of Ti-6Al-4V Plates Consolidated from Low Cost Powders

    Science.gov (United States)

    Imam, M. Ashraf; Pao, Peter S.; Bayles, Robert A.

    Titanium is highly desirable for a wide range of applications because of its combination of high strength, low density and outstanding corrosion characteristics. However, the cost of titanium, produced by conventional technology, is high compared to steel and aluminum, which is a result of high extraction and processing costs. New approaches are being investigated maintaining required quality while lowering the cost of finished products. Ti alloy powder, Ti-6Al-4V, manufactured by a low cost hydride-process and consolidated into flat products (sheet, plate), were studied. The results of the study were compared with the properties obtained from plates of Armstrong Titanium consolidated powder. To remove the prior history of consolidation, the plates are beta annealed and the test results are compared with "as received" condition. The mechanism of the fatigue crack growth rate difference, fracture toughness, and stress-corrosion cracking resistance in terms of the respective Ti-6Al-4V microstructure differences will be discussed.

  15. Process Parameter Optimization for Wobbling Laser Spot Welding of Ti6Al4V Alloy

    Science.gov (United States)

    Vakili-Farahani, F.; Lungershausen, J.; Wasmer, K.

    Laser beam welding (LBW) coupled with "wobble effect" (fast oscillation of the laser beam) is very promising for high precision micro-joining industry. For this process, similarly to the conventional LBW, the laser welding process parameters play a very significant role in determining the quality of a weld joint. Consequently, four process parameters (laser power, wobble frequency, number of rotations within a single laser pulse and focused position) and 5 responses (penetration, width, heat affected zone (HAZ), area of the fusion zone, area of HAZ and hardness) were investigated for spot welding of Ti6Al4V alloy (grade 5) using a design of experiments (DoE) approach. This paper presents experimental results showing the effects of variating the considered most important process parameters on the spot weld quality of Ti6Al4V alloy. Semi-empirical mathematical models were developed to correlate laser welding parameters to each of the measured weld responses. Adequacies of the models were then examined by various methods such as ANOVA. These models not only allows a better understanding of the wobble laser welding process and predict the process performance but also determines optimal process parameters. Therefore, optimal combination of process parameters was determined considering certain quality criteria set.

  16. Fatigue Behavior of Porous Ti-6Al-4V Made by Laser-Engineered Net Shaping

    Science.gov (United States)

    Bordonaro, Giancarlo G.; Berto, Filippo

    2018-01-01

    The fatigue behavior and fracture mechanisms of additively manufactured Ti-6Al-4V specimens are investigated in this study. Three sets of testing samples were fabricated for the assessment of fatigue life. The first batch of samples was built by using Laser-Engineered Net Shaping (LENS) technology, a Direct Energy Deposition (DED) method. Internal voids and defects were induced in a second batch of samples by changing LENS machine processing parameters. Fatigue performance of these samples is compared to the wrought Ti-6Al-4V samples. The effects of machine-induced porosity are assessed on mechanical properties and results are presented in the form of SN curves for the three sets of samples. Fracture mechanisms are examined by using Scanning Electron Microscopy (SEM) to characterize the morphological characteristics of the failure surface. Different fracture surface morphologies are observed for porous and non-porous specimens due to the combination of head write speed and laser power. Formation of defects such as pores, unmelted regions, and gas entrapments affect the failure mechanisms in porous specimens. Non-porous specimens exhibit fatigue properties comparable with that of the wrought specimens, but porous specimens are found to show a tremendous reduced fatigue strength. PMID:29439510

  17. The Effect of Friction Stir Welding on Corrosion Behavior of Ti-6Al-4V

    Science.gov (United States)

    Nasresfahani, Ali Reza; Soltanipur, Abdol Reza; Farmanesh, Khosro; Ghasemi, Ali

    2017-09-01

    Fusion welding can deteriorate corrosion behavior of Ti-6Al-4V alloy. However, the use of friction stir welding leads to a more appropriate corrosion resistance. In this study, the corrosion resistance of welded zones of Ti-6Al-4V alloy using friction stir welding technique is evaluated. For these purposes, the study of structural characteristics using SEM and FESEM equipped with EDS micro-analyses was conducted. Micro-hardness test was also employed to estimate the hardness of welded zones. Corrosion behavior was investigated by a potentiostat instrument. SEM micrographs, EDS and XRD analyses confirmed non-uniformity of chemical composition within the welded zones. The results reveal that the stir zone contains typical alpha and prior beta phases. Nevertheless, thermomechanical zone included equiaxed and bimodal lamellae structure. Furthermore, the presence of different types of phases and microstructure in the thermomechanical zone led to reduced corrosion resistance. The corresponding values of corrosion current density in the stir zone, thermomechanical zone and base metal were 0.048, 0.55 and 0.032 µA, respectively. Corresponding corrosion potential for these zones was estimated as -207, -110 and -157 mV. Evidently, the results show that corrosion resistance of thermomechanical zone is less than that of the stir zone and both zones have lower value than the base metal.

  18. Influence of Material Microstructures in Micromilling of Ti6Al4V Alloy

    Directory of Open Access Journals (Sweden)

    Claudio Giardini

    2013-09-01

    Full Text Available In the most recent decades the introduction of unconventional machining processes allowed the development of micromachining techniques. In this work, the influence of material microstructures on the micromilling process was investigated. Ti6Al4V alloy was selected as workpiece material since it is a very common material for micro applications and because its duplex microstructure can be easily changed by proper thermal treatments. Four different microstructures (namely bimodal, fully equiaxed, fully lamellar and mill annealed were obtained through recrystallization annealing treatments carried out at different times and temperatures. The mechanical properties of the samples were assessed by microhardness measurements. Nano-indentations were also performed on single grains to understand how the different hardness of phases and structures present in the Ti6Al4V alloy can affect the micromilling process. Microchannels using two flute flat end mills with a diameter equal to 200 µm were realized on the treated samples. Two different feed-per-tooth values were used during the tests. Cutting force, channel shape and burr dimension were investigated. Morphological and energy dispersive spectroscopy (EDS analyses were performed on tools by means of a scanning electron microscope (SEM: in this way the phenomena mainly influencing the tool status were also identified. Lower cutting forces and reduced tool wear were observed when working fully lamellar microstructures compared to the other ones.

  19. OVERVIEW OF WORK PIECE TEMPERATURE MEASUREMENT TECHNIQUES FOR MACHINING OF Ti6Al4V#

    Directory of Open Access Journals (Sweden)

    P.J.T. Conradie

    2012-01-01

    Full Text Available

    ENGLISH ABSTRACT: Ti6Al4V is one of the most widely used titanium alloys in aerospace applications, but its machining remains a challenge. Comprehensive research has been done in the past, mainly investigating tool failure of various materials. Less research has been done to investigate the thermal effect of machining on work piece quality, including fatigue performance. Temperature measurement is considered to be a key enabling technology. This study presents an overview of current temperature measurement techniques for machined and tool surfaces. Two categories of methods were investigated: slower contact, and faster optical methods. Optical fibre two colour pyrometry experiments are reported that demonstrate the technique’s adequate response time. The infrared camera temperature measurement experiments synchronised temperature measurement with visual observation, aimed at mechanism analysis. The results corresponded with the literature.

    AFRIKAANSE OPSOMMING: Ti6Al4V is een van die mees gewilde lugvaart allooie, maar sy masjinering is ’n uitdaging. Bestaande navorsing dek beitelslytasie omvattend. Die termiese effek van masjinering op werkstuk integriteit, insluitend vermoeiingleeftyd, het egter veel minder dekking geniet. Temperatuurmeting wat in hierdie studie ondersoek word, word as ’n sleuteltegnologie beskou. Twee kategorië metodes is ondersoek, nl stadige kontakmetodes en optiese metodes met vinnige respons, wat die meting van oorgangsverskynsels moontlik maak. Eksperimentele werk wat beide optiese vesel tweekleurpirometrie en termiese kamera tegnieke insluit bewys die tegnieke as geskik vir die benodigde navorsing.

  20. Micromilling of Ti-6Al-4V Titanium Alloy Using Ball-end Tool

    Science.gov (United States)

    Pratap, T.; Patra, K.

    2017-09-01

    The present work experimentally investigates the characteristics of micromilling of Ti-6Al-4V workpiece using ball-end tool. Micromilling were performed using 400 ¼m ball-end milling tool with the consideration of effective tool diameter. The effective tool diameter in ball-end milling is different from flat-end milling due to variation in cutting zone with axial depth of cut which accounts actual cutting speed and feed the machining. Process input variables includes cutting speed, feed per tooth and axial depth of cut, each with three levels, whereas cutting forces and surface roughness as process responses. Response surface methodology (RSM) based quadratic regression analysis was utilized to develop the correlation between process inputs and responses. Experimental results of present study on micromilling of Ti-6Al-4V using ball-end tool showed that axial depth of cut and feed per tooth could significantly influence the cutting forces and surface roughness. However, present study shows cutting speed has least effect on process responses. Finally, suitable set of process variables were proposed based multi objective optimization approach to obtain minimum cutting forces and surface roughness which were also validated with conformation test results.

  1. Feasibility study of the production of biomedical Ti-6Al-4V alloy by powder metallurgy.

    Science.gov (United States)

    Bolzoni, L; Ruiz-Navas, E M; Gordo, E

    2015-04-01

    Titanium and its alloys are characterized by an exceptional combination of properties like high strength, good corrosion resistance and biocompatibility which makes them suitable materials for biomedical prosthesis and devices. The wrought Ti-6Al-4V alloy is generally favored in comparison to other metallic biomaterials due to its relatively low elastic modulus and it has been long used to obtain products for biomedical applications. In this work an alternative route to fabricate biomedical implants made out of the Ti-6Al-4V alloy is investigated. Specifically, the feasibility of the conventional powder metallurgy route of cold uniaxial pressing and sintering is addressed by considering two types of powders (i.e. blended elemental and prealloyed). The characterization of physical properties, chemical analysis, mechanical behavior and microstructural analysis is carried out in-depth and the properties are correlated among them. On the base of the results found, the produced alloys are promising materials for biomedical applications as well as cheaper surgical devices and tools. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Roughness Influence on Initiation of Fretting Fatigue Scar of Ti-6Al-4V Alloy

    Science.gov (United States)

    Capitanu, L.; Badita, L. L.; Florescu, V.; Tiganesteanu, C.

    2018-01-01

    This paper reports on the experimental studies undertaken to detect the early stage when appears the fretting wear of the Ti-6Al-4V alloy used for the hip prostheses. Wear is a critical aspect for estimating the fretting fatigue. Studies were performed on samples of special shape, in order to be able to study the influence of in contact surfaces roughness on the durability to fretting. Fretting buffers, with roughnesses Ra of the contact surface of 0.015 and 0.045 μm, and Ti-6Al-4V samples with roughnesses Ra = 0.045 μm, Ra = 0.075 μm and Ra = 0.19 μm, were used. Testing periods of 3 seconds, 1 minute and 5 minutes were selected to capture the moment of the fretting scar appearance, long before these initiate the eventual fretting cracking. Simultaneously with fretting wear of the surface, the friction coefficient was also measured. From the in time evolution determinations of the fretting wear, it resulted that, under the experimental conditions used, the minimum wear occurs at a certain value of the roughness and not at the minimum roughness. Surprisingly, the minimum friction coefficient does not coincide with the minimum fretting wear.

  3. Study of the dynamic Bauschinger effect in Ti6Al4V by torsion experiments

    Directory of Open Access Journals (Sweden)

    Degrieck J.

    2012-08-01

    Full Text Available The materials kinematic hardening behaviour and Bauschinger effect is indispensible to describe complex deformation processes involving strain path changes. Moreover, the Bauschinger effect provides valuable information about underlying microstructural plasticity mechanisms. Until now, the Bauschinger effect at high strain rates remains a largely unexplored topic. However, different studies demonstrated the strain rate dependent character of the Bauschinger effect. The aim of this work is to study the dynamic Bauschinger effect by means of a novel experimental technique. A modified torsional split Hopkinson bar setup is used to conduct Bauschinger experiments on Ti6Al4V. Forward and reverse loading of the specimen take place successively in only one experiment. This has the advantage of having the same thermal conditions during the two loading cycles. Besides high strain rate tests, quasi-static torsional Bauschinger experiments are conducted. The Bauschinger effect at the different strain rates is quantified with a dimensionless Bauschinger stress parameter. It is found that the Bauschinger effect is present at all tested strain rates. However, it is more pronounced at high strain rates. This implies that the kinematic hardening of Ti6Al4V is strain rate sensitive.

  4. Surface hardening of Ti-6Al-4V alloy by hydrogenation

    International Nuclear Information System (INIS)

    Wu, T.I.; Wu, J.K.

    1991-01-01

    Thermochemical processing is an advanced method to enhance the fabricability and mechanical properties of titanium alloys. In this process hydrogen is added to the titanium alloy as a temporary alloying element. Hydrogen addition lowers the β transus temperature of titanium alloy and stabilizes the β phase. The increased amount of β phase in hydrogen-modified titanium alloys reduces the grain growth rate during eutectoid β → α + hydride reaction. Hydrogen was added to the titanium alloy by holding it at a relatively high temperature in a hydrogen gaseous environment in previous studies. Pattinato reported that Ti-6Al-4V alloy can react with hydrogen gas at ambient temperature and cause a serious hydrogen embrittlement problem. The hydrogen must be removed to a low allowable concentration in a vacuum system after the hydrogenation process. The present study utilized an electrochemical technique to dissolve hydrogen into titanium alloy to replace the hydrogen environment in thermochemical processing. In this paper microstructures and hardnesses of this new processed Ti-6Al-4V alloy are reported

  5. Evaluation of shot peening on the fatigue strength of anodized Ti-6Al-4V alloy

    Directory of Open Access Journals (Sweden)

    Costa Midori Yoshikawa Pitanga

    2006-01-01

    Full Text Available The increasingly design requirements for modern engineering applications resulted in the development of new materials with improved mechanical properties. Low density, combined with excellent weight/strength ratio as well as corrosion resistance, make the titanium attractive for application in landing gears. Fatigue control is a fundamental parameter to be considered in the development of mechanical components. The aim of this research is to analyze the fatigue behavior of anodized Ti-6Al-4V alloy and the influence of shot peening pre treatment on the experimental data. Axial fatigue tests (R = 0.1 were performed, and a significant reduction in the fatigue strength of anodized Ti-6Al-4V was observed. The shot peening superficial treatment, which objective is to create a compressive residual stress field in the surface layers, showed efficiency to increase the fatigue life of anodized material. Experimental data were represented by S-N curves. Scanning electron microscopy technique (SEM was used to observe crack origin sites.

  6. Fabrication Of Scaffolds From Ti6Al4V Powders Using The Computer Aided Laser Method

    Directory of Open Access Journals (Sweden)

    Dobrzański L.A.

    2015-06-01

    Full Text Available The aim of the research, the results of which are presented in the paper, is to fabricate, by Selective Laser Melting (SLM, a metallic scaffold with Ti6Al4V powder based on a virtual model corresponding to the actual loss of a patient’s craniofacial bone. A plaster cast was made for a patient with a palate recess, and the cast was then scanned with a 3D scanner to create a virtual 3D model of a palate recess, according to which a 3D model of a solid implant was created using specialist software. The virtual 3D solid implant model was converted into a 3D porous implant model after designing an individual shape of the unit cell conditioning the size and three-dimensional shape of the scaffold pores by multiplication of unit cells. The data concerning a virtual 3D porous implant model was transferred into a selective laser melting (SLM device and a metallic scaffold was produced from Ti6Al4V powder with this machine, which was subjected to surface treatment by chemical etching. An object with certain initially adopted assumptions, i.e. shape and geometric dimensions, was finally achieved, which perfectly matches the patient bone recesses. The scaffold created was subjected to micro-and spectroscopic examinations.

  7. Tribological behavior of Ti6Al4V cellular structures produced by Selective Laser Melting.

    Science.gov (United States)

    Bartolomeu, F; Sampaio, M; Carvalho, O; Pinto, E; Alves, N; Gomes, J R; Silva, F S; Miranda, G

    2017-05-01

    Additive manufacturing (AM) technologies enable the fabrication of innovative structures with complex geometries not easily manufactured by traditional processes. Regarding metallic cellular structures with tailored/customized mechanical and wear performance aiming to biomedical applications, Selective Laser Melting (SLM) is a remarkable solution for their production. Focusing on prosthesis and implants, in addition to a suitable Young's modulus it is important to assess the friction response and wear resistance of these cellular structures in a natural environment. In this sense, five cellular Ti6Al4V structures with different open-cell sizes (100-500µm) were designed and produced by SLM. These structures were tribologicaly tested against alumina using a reciprocating sliding ball-on-plate tribometer. Samples were submerged in Phosphate Buffered Saline (PBS) fluid at 37°C, in order to mimic in some extent the human body environment. The results showed that friction and wear performance of Ti6Al4V cellular structures is influenced by the structure open-cell size. The higher wear resistance was obtained for structures with 100µm designed open-cell size due to the higher apparent area of contact to support tribological loading. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Rupture Predictions of Notched Ti-6Al-4V Using Local Approaches

    Directory of Open Access Journals (Sweden)

    Mirco Peron

    2018-04-01

    Full Text Available Ti-6Al-4V has been extensively used in structural applications in various engineering fields, from naval to automotive and from aerospace to biomedical. Structural applications are characterized by geometrical discontinuities such as notches, which are widely known to harmfully affect their tensile strength. In recent years, many attempts have been done to define solid criteria with which to reliably predict the tensile strength of materials. Among these criteria, two local approaches are worth mentioning due to the accuracy of their predictions, i.e., the strain energy density (SED approach and the theory of critical distance (TCD method. In this manuscript, the robustness of these two methods in predicting the tensile behavior of notched Ti-6Al-4V specimens has been compared. To this aim, two very dissimilar notch geometries have been tested, i.e., semi-circular and blunt V-notch with a notch root radius equal to 1 mm, and the experimental results have been compared with those predicted by the two models. The experimental values have been estimated with low discrepancies by either the SED approach and the TCD method, but the former results in better predictions. The deviations for the SED are in fact lower than 1.3%, while the TCD provides predictions with errors almost up to 8.5%. Finally, the weaknesses and the strengths of the two models have been reported.

  9. Qualification of Ti6Al4V ELI Alloy Produced by Laser Powder Bed Fusion for Biomedical Applications

    Science.gov (United States)

    Yadroitsev, I.; Krakhmalev, P.; Yadroitsava, I.; Du Plessis, A.

    2018-03-01

    Rectangular Ti6Al4V extralow interstitials (ELI) samples were manufactured by laser powder bed fusion (LPBF) in vertical and horizontal orientations relative to the build platform and subjected to various heat treatments. Detailed analyses of porosity, microstructure, residual stress, tensile properties, fatigue, and fracture surfaces were performed based on x-ray micro-computed tomography, scanning electron microscopy, and x-ray diffraction methods. The types of fracture and the tensile fracture mechanisms of the LPBF Ti6Al4V ELI alloy were also studied. Detailed analysis of the microstructure and the corresponding mechanical properties were compared against standard specifications for conventional Ti6Al4V alloy for use in surgical implant applications. Conclusions regarding the mechanical properties and heat treatment of LPBF Ti6Al4V ELI for biomedical applications are made.

  10. Osseointegration of loaded dental implant with KrF laser hydroxylapatite films on Ti6Al4V alloy by minipigs

    Science.gov (United States)

    Dostalova, Tatjana; Himmlova, Lucia; Jelinek, Miroslav; Grivas, Christos

    2001-04-01

    This study was performed with the objective of evaluating osseointegration of titanium alloy Ti6Al4V dental implants coated with hydroxylapatite (HA) deposited by a KrF laser. For this a KrF excimer laser and stainless-steel deposition chamber were used. The thickness of the HA films was approximately 1 micrometers . IN this investigation experimental animals minipigs were used; the implants were placed vertically into the lower jaw. After 14 weeks of unloaded osseointegration, metal-ceramic crowns were inserted and, at the same time, fluorescent solution was injected into the experimental animals. Six months after insertion of crowns the animals were sacrificed. The vertical position of the implants was checked by a radiograph. Microscopic sections were cut and ground, and the sections were examined under polarized and fluorescent light using a microscope with a charge coupled device camera. The six month long osseointegration in the lower jaw has confirmed the presence of newly formed bone around all the implants. In the experimental group, which had a laser-deposited coating, the layer of fibrous connective tissue was seen only randomly. In the control group (titanium implant without a cover) the fibrous connective tissue between the implant and the newly formed bone was observed more frequently, but this difference was not significant.

  11. Energy Barriers and Driving Forces Associated with the Dynamic Transformation of Ti-6Al-4V (Preprint)

    Science.gov (United States)

    2017-12-11

    AFRL-RX-WP-JA-2017-0516 ENERGY BARRIERS AND DRIVING FORCES ASSOCIATED WITH THE DYNAMIC TRANSFORMATION OF TI-6AL-4V (PREPRINT) S.L...TYPE 3. DATES COVERED (From - To) 11 December 2017 Interim 19 March 2014 – 11 November 2017 4. TITLE AND SUBTITLE ENERGY BARRIERS AND DRIVING FORCES...The energy barriers and driving forces associated with dynamic transformation in Ti-6Al-4V are evaluated. It is shown that the stored energy is less

  12. Microstructure and Properties of TiB/Ti-6Al-4V Coatings Produced With Laser Treatments

    NARCIS (Netherlands)

    Galvan, D.; Ocelík, V.; Pei, Y.; Kooi, B.J.; Hosson, Jeff Th.M. De; Ramous, E.

    2004-01-01

    TiB/Ti-6Al-4V metal-matrix composite (MMC) layers were produced on Ti-6Al-4V substrates by laser cladding. A TiB2/Ti powder mixture was used as a precursor to obtain a dispersion of TiB needles in the Ti alloy matrix, with the aid of an exothermic reaction between TiB2 and Ti. A eutectic

  13. Strain simulation in face turning of Ti6Al4V thin-walled parts

    Science.gov (United States)

    Struzikiewicz, Grzegorz; Zebala, Wojciech

    2017-08-01

    An analysis of the part deformation in the face turning of the grooves was presented. A face-grooving process was performed on the disc-shaped part made of titanium alloy Ti6Al4V. Investigations were performed in two stages. First, experimental studies were conducted to determine the level of the cutting forces for variable wall thickness and cutting data. In the second step of investigations, a computer simulation of the disc flange deformation was performed using finite element method in the NX Siemens software. Based on the analysis of the research results, the dependence of the direction and value of the cutting force on the deformation value has been determined.

  14. Influence of Microtexture on Early Plastic Slip Activity in Ti-6Al-4V Polycrystals

    Science.gov (United States)

    Hémery, Samuel; Dang, Van Truong; Signor, Loïc; Villechaise, Patrick

    2018-03-01

    Microtextured regions are known to influence the fatigue performance of titanium alloys. Previous studies revealed that crack initiation, accounting for most of the fatigue life, is triggered by slip activity. The influence of microtextured regions on the early plastic slip activity was presently investigated by means of an in situ tensile test performed inside a scanning electron microscope on a bimodal Ti-6Al-4V polycrystalline specimen. A slip trace analysis was carried out in several regions with different crystallographic textures to highlight potentially different deformation behaviors. Significant stress heterogeneities were revealed through an early slip activation in microtextured regions with a predominant [0001] orientation. This point was shown to be related to a locally increased resolved shear stress. Consequences on behavior under cyclic loadings are finally discussed.

  15. Load relaxation behavior of ultra-fine grained Ti-6Al-4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Y.G.; Kim, J.H.; Lee, C.S. [Dept. of Materials Science and Engineering, Pohang Univ. of Science and Technology, Pohang (Korea); Shin, D.H. [Dept. of Metallurgy and Materials Science, Hanyang Univ., Ansan, Gyeonggi-do (Korea); Semiatin, S.L. [Air Force Research Lab., Materials and Mfg. Directorate Wright-Patterson AFB, OH (United States)

    2005-07-01

    In this study, superplastic deformation behavior of ultrafine-grained Ti-6Al-4V alloy was investigated on the basis of the inelastic deformation theory which consists of grain matrix deformation and grain boundary sliding. Specimens with coarse equiaxed grains (11 {mu}m in diameter) were significantly refined ({approx}0.3 {mu}m in diameter) with high angle boundaries after 4 times of isothermal equal channel angular (ECA) pressing at 600 C. Load relaxation test was performed at 600{proportional_to}700 C to enlighten the deformation mechanisms operating at specific temperature and to find optimum superplastic forming conditions for ultrafine-grained structures. Main efforts were devoted to analyze quantitatively the relative amount of each deformation mode, i.e., dislocation glide and grain boundary sliding operating at specific temperature. (orig.)

  16. Influence of Milling on the Fatigue Lifetime of a Ti6Al4V Titanium Alloy

    Directory of Open Access Journals (Sweden)

    Kamel Moussaoui

    2015-06-01

    Full Text Available The present article focuses on the influence of machining on the fatigue life of a titanium alloy: Ti6Al4V. An experimental design was adopted in order to highlight the effects of machining parameters on surface integrity while generating very different surfaces with a view to subsequent fatigue testing (four point bending tests. Firstly, the impact of machining parameters on surface integrity was demonstrated. Then, the influence of surface integrity on fatigue lifetime was observed: no influence of the geometric and metallurgical parameters was observed. However, the mechanical parameter (e.g., residual stress seemed to have a preponderant influence. To conclude, a machining plan of procedure was proposed to significantly improve the fatigue lifetime as compared with a reference industrial plan of procedure.

  17. Trends in Solidification Grain Size and Morphology for Additive Manufacturing of Ti-6Al-4V

    Science.gov (United States)

    Gockel, Joy; Sheridan, Luke; Narra, Sneha P.; Klingbeil, Nathan W.; Beuth, Jack

    2017-12-01

    Metal additive manufacturing (AM) is used for both prototyping and production of final parts. Therefore, there is a need to predict and control the microstructural size and morphology. Process mapping is an approach that represents AM process outcomes in terms of input variables. In this work, analytical, numerical, and experimental approaches are combined to provide a holistic view of trends in the solidification grain structure of Ti-6Al-4V across a wide range of AM process input variables. The thermal gradient is shown to vary significantly through the depth of the melt pool, which precludes development of fully equiaxed microstructure throughout the depth of the deposit within any practical range of AM process variables. A strategy for grain size control is demonstrated based on the relationship between melt pool size and grain size across multiple deposit geometries, and additional factors affecting grain size are discussed.

  18. Microstructure and mechanical properties of selective laser melted Ti6Al4V alloy

    Science.gov (United States)

    Losertová, M.; Kubeš, V.

    2017-11-01

    The present work was focused on the properties of porous Ti6Al4V specimens processed by selective laser melting (SLM) and tested in tension and compression before and after heat treatment. The SLM samples were annealed at 955 °C, water quenched and aged at 600 °C with following air cooling. The values of the mechanical tests showed that the samples exhibited high mechanical properties. The anisotropy of tensile and compressive strength was observed, which was related to the occurrence of voids. The plastic properties of specimens were improved by means of the heat treatment that led to the transformation of martensitic to lamellar structure composed of α + β phases. The microstructure of SLM samples were evaluated before and after the heat treatment. The brittle nature of failures of non-heat treated samples can be explained by synergy of martensite presence, microcracks and residual stresses produced by SLM.

  19. Analyzing the compressive behavior of porous Ti6Al4V by X-ray microtomography

    Energy Technology Data Exchange (ETDEWEB)

    Farias, Iván; Jimenez, Omar; Flores, Martín [Departamento de Ingeniería de Proyectos, Universidad de Guadalajara, Jalisco (Mexico); Olmos, Luís, E-mail: luisra24@gmail.com [Instituto de Investigaciones en Ciencias de la Tierra (INICIT), Universidad Michoacana de San Nicolás de Hidalgo, Michoacán (Mexico); Vergara-Hernández, Héctor Javier; Gárnica, Pedro [Instituto Tecnológico de Morelia, Michoacán (Mexico); Bouvard, Didier [Science et Ingénierie des Matériaux et Procédés (SIMaP), Université Grenoble Alpes (France)

    2017-11-15

    Samples with 40% vol. of pores and a pore size distribution between 100 and 500 μm were produced by powder metallurgy from Ti6Al4V alloy powders. Sintering was performed at 1300 °C during one hour in an inert Argon atmosphere in a vertical dilatometer. The compressive strength and the porosity of these samples was investigated before and after compression tests through X-ray microtomography. The values of the elastic modulus (8GPa) and yield strength (80MPa) are within the range of those used in bone implants. Porosity leads to greater deformation whereas fracture of compacts occurs perpendicularly to the applied load. It was determined that the origin of the failure is generated by rupture of interparticle necks and, large pores enhance the propagation of cracks. (author)

  20. The Transverse Rupture Strength in Ti-6Al-4V Alloy Manufactured by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Lai Pang-Hsin

    2015-01-01

    Full Text Available The objective of this study was to investigate the transverse rupture strength and apparent hardness of selective laser melted Ti-6Al-4V alloys manufactured in the vertical (V and horizontal (H directions. The microstructure and the distribution of alloy elements were examined by optical microscope and electron probe microanalysis, respectively. The results show that the columnar α′ grains are formed along the building direction, and the elemental distributions of Ti, Al, and V are homogeneous in the alloy. The building direction does not sufficiently affect the density and apparent hardness. However, the transverse rupture strengths (TRS are obviously dominated by the building directions investigated in this study. The TRS of an H specimen is significantly superior to that of a V specimen by 48%. This phenomenon can be mainly attributed to the presence of disc-shaped pores.

  1. Analyzing the compressive behavior of porous Ti6Al4V by X-ray microtomography

    International Nuclear Information System (INIS)

    Farias, Iván; Jimenez, Omar; Flores, Martín; Olmos, Luís; Vergara-Hernández, Héctor Javier; Gárnica, Pedro; Bouvard, Didier

    2017-01-01

    Samples with 40% vol. of pores and a pore size distribution between 100 and 500 μm were produced by powder metallurgy from Ti6Al4V alloy powders. Sintering was performed at 1300 °C during one hour in an inert Argon atmosphere in a vertical dilatometer. The compressive strength and the porosity of these samples was investigated before and after compression tests through X-ray microtomography. The values of the elastic modulus (8GPa) and yield strength (80MPa) are within the range of those used in bone implants. Porosity leads to greater deformation whereas fracture of compacts occurs perpendicularly to the applied load. It was determined that the origin of the failure is generated by rupture of interparticle necks and, large pores enhance the propagation of cracks. (author)

  2. CO{sub 2} laser gas assisted nitriding of Ti-6Al-4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yilbas, B.S. [KFUPM, Dhahran (Saudi Arabia)]. E-mail: bsyilbas@kfupm.edu.sa; Karatas, C. [Hacettepe University, Ankara (Turkey); Uslan [Gazi University, Ankara (Turkey); Keles, O. [Gazi University, Ankara (Turkey); Usta, I.Y. [Gazi University, Ankara (Turkey); Ahsan, M. [KFUPM, Dhahran (Saudi Arabia)

    2006-10-15

    Laser gas assisted nitriding of Ti-6Al-4V alloy is carried out and nitride compounds formed and their concentration in the surface vicinity are examined. SEM, XRD and XPS are accommodated to examine the nitride layer characteristics. Microhardness across the nitride layer is measured. Temperature field and nitrogen distribution due to laser irradiation pulse is predicted. It is found that the nitride layer appears like golden color; however, it becomes dark gold color once the laser power irradiation is increased. The {delta}-TiN and {epsilon}-TiN are dominant phases in the surface vicinity. The needle like dendrite structure replace with the feathery like structure in the surface region due to high nitrogen concentration. No porous or microcracks are observed in the nitrided layer, except at high power irradiation, in this case, elongated cracks are observed in the surface region where the nitrogen concentration is considerably high.

  3. Study of creep of Ti-6Al-4V alloy using plasma immersion ion implantation (PIII)

    International Nuclear Information System (INIS)

    Zepka, Susana; Yogi, Lucila Mayumi; Silva, Maria Margareth da; Reis, Danieli Aparecida Pereira; Moura Neto, Carlos de; Oliveira, Vinicius Souza de; Ueda, Mario

    2010-01-01

    This study aims to investigate the creep resistance of the Ti-6Al-4V alloy after surface modification by plasma immersion ion implantation (PIII). For the PIII treatment it was used nitrogen gas (ion implantation) to the formation of plasma, the material was treated for 100 minutes. After PIII treatment the samples were analyzed using the techniques of X-ray diffraction, spectrometry energy dispersive X-ray and atomic force microscopy. The creep tests were realized at 600°C, at constant load of 250 and 319 MPa. After the creep tests the samples were analyzed by optical microscopy and scanning electron microscopy. By chemical analysis by X-ray and EDS it is possible to determinate the Ti 2 N on the surface. Through the study of the creep curves it is observed an increasing in creep resistance of the alloy after PIII treatment. (author)

  4. Grain Refinement of Freeform Fabricated Ti-6Al-4V Alloy Using Beam/Arc Modulation

    Science.gov (United States)

    Mitzner, Scott; Liu, Stephen; Domack, Marcia S.; Hafley, Robert A.

    2012-01-01

    Grain refinement can significantly improve the mechanical properties of freeform-fabricated Ti-6Al-4V alloy, promoting increased strength and enhanced isotropy compared with coarser grained material. Large beta-grains can lead to a segregated microstructure, in regard to both alpha-phase morphology and alpha-lath orientation. Beam modulation, which has been used in conventional fusion welding to promote grain refinement, is explored in this study for use in additive manufacturing processes including electron beam freeform fabrication (EBF(sup 3)) and gas-tungsten arc (GTA) deposition to alter solidification behavior and produce a refined microstructure. The dynamic molten pool size induced by beam modulation causes rapid heat flow variance and results in a more competitive grain growth environment, reducing grain size. Consequently, improved isotropy and strength can be achieved with relatively small adjustments to deposition parameters.

  5. Microstructure Evolution in Cut Metal Chips of Ti-6Al-4V

    Science.gov (United States)

    Dong, L.; Schneider, J. A.

    2008-01-01

    The microstructural evolution following metal cutting was investigated within metal chips of Ti-6Al-4V. Metal cutting was used to impose a high strain rate on the order of approx.10(exp 5)/s within the primary shear zone as the metal was removed from the workpiece. The initial microstructure of the parent material (PM) was composed of a bi-modal microstructure with coarse prior beta grains and equiaxed primary alpha located at the boundaries. After metal cutting, the microstructure of the metal chips showed coarsening of the equiaxed primary alpha grains and beta lamellar. These metallographic findings suggest that the metal chips experienced high temperatures which remained below the beta transus temperature.

  6. Consequences of Part Temperature Variability in Electron Beam Melting of Ti-6Al-4V

    Science.gov (United States)

    Fisher, Brian A.; Mireles, Jorge; Ridwan, Shakerur; Wicker, Ryan B.; Beuth, Jack

    2017-12-01

    To facilitate adoption of Ti-6Al-4V (Ti64) parts produced via additive manufacturing (AM), the ability to ensure part quality is critical. Measuring temperatures is an important component of part quality monitoring in all direct metal AM processes. In this work, surface temperatures were monitored using a custom infrared camera system attached to an Arcam electron beam melting (EBM®) machine. These temperatures were analyzed to understand their possible effect on solidification microstructure based on solidification cooling rates extracted from finite element simulations. Complicated thermal histories were seen during part builds, and temperature changes occurring during typical Ti64 builds may be large enough to affect solidification microstructure. There is, however, enough time between fusion of individual layers for spatial temperature variations (i.e., hot spots) to dissipate. This means that an effective thermal control strategy for EBM® can be based on average measured surface temperatures, ignoring temperature variability.

  7. Yield Behavior of Solution Treated and Aged Ti-6Al-4V

    Science.gov (United States)

    Ring, Andrew J.; Baker, Eric H.; Salem, Jonathan A.; Thesken, John C.

    2014-01-01

    Post yield uniaxial tension-compression tests were run on a solution treated and aged (STA), titanium 6-percent aluminum 4-percent vanadium (Ti-6Al-4V) alloy to determine the yield behavior on load reversal. The material exhibits plastic behavior almost immediately on load reversal implying a strong Bauschinger effect. The resultant stress-strain data was compared to a 1D mechanics model and a finite element model used to design a composite overwrapped pressure vessel (COPV). Although the models and experimental data compare well for the initial loading and unloading in the tensile regime, agreement is lost in the compressive regime due to the Bauschinger effect and the assumption of perfect plasticity. The test data presented here are being used to develop more accurate cyclic hardening constitutive models for future finite element design analysis of COPVs.

  8. Surface modification of Ti6Al4V by nanosecond laser ablation for biomedical applications

    Science.gov (United States)

    Fiorucci, M. P.; López, A. J.; Ramil, A.

    2015-04-01

    This paper presents the surface textured process of biometal Ti6Al4V by means of 355 nm Nd:YVO4 nanosecond laser. Our target is to create structures with sizes which favour osseointegration. In this work a pattern of parallel grooves was generated after a deep analysis of the irradiation parameters involved. Ablation modifies not only the topography but also physico-chemical properties of the metal surface. Changes in the morphology and the physico-chemical state of the laser induced groove pattern were studied by a scanning electron microscopy, X-ray diffraction and X- ray photoelectron spectroscopy, which revealed, among others, an increase of micro roughness and a oxide layer entirely formed by TiO2, which can improve biocompatibility properties of the textured surface.

  9. Effect of traverse speed on abrasive waterjet machining of Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Hascalik, Ahmet; Caydas, Ulas; Gueruen, Hakan

    2007-01-01

    In the presented study, Ti-6Al-4V alloy, known as one of the difficult-to-machine materials using conventional machining processes, was machined under varying traverse speeds of 60, 80, 120, 150, 200, and 250 mm/min by abrasive waterjet (AWJ) machining. After machining, the profiles of machined surfaces, kerf geometries and microstructural features of the machined surfaces were examined using surface profilometry and scanning electron microscopy (SEM). The experimental results indicate that the traverse speed of the jet is a significant parameter on the surface morphology, and the widths and features of different regions formed in the cutting surface change according to the traverse speed. It was also observed that the kerf taper ratio and surface roughness increase with increasing traverse speed in chosen conditions

  10. Effect of traverse speed on abrasive waterjet machining of Ti-6Al-4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hascalik, Ahmet [University of Firat, Technical Education Faculty, Department of Manufacturing, Elazig (Turkey)]. E-mail: ahascalik@firat.edu.tr; Caydas, Ulas [University of Firat, Technical Education Faculty, Department of Manufacturing, Elazig (Turkey); Gueruen, Hakan [University of Gazi, Technical Education Faculty, Department of Manufacturing, Ankara (Turkey)

    2007-07-01

    In the presented study, Ti-6Al-4V alloy, known as one of the difficult-to-machine materials using conventional machining processes, was machined under varying traverse speeds of 60, 80, 120, 150, 200, and 250 mm/min by abrasive waterjet (AWJ) machining. After machining, the profiles of machined surfaces, kerf geometries and microstructural features of the machined surfaces were examined using surface profilometry and scanning electron microscopy (SEM). The experimental results indicate that the traverse speed of the jet is a significant parameter on the surface morphology, and the widths and features of different regions formed in the cutting surface change according to the traverse speed. It was also observed that the kerf taper ratio and surface roughness increase with increasing traverse speed in chosen conditions.

  11. Corrosion of Ti6Al4V pins produced by direct metal laser sintering

    Science.gov (United States)

    de Damborenea, J. J.; Arenas, M. A.; Larosa, Maria Aparecida; Jardini, André Luiz; de Carvalho Zavaglia, Cecília Amélia; Conde, A.

    2017-01-01

    Direct Metal Laser Sintering (DMLS) technique allows the manufacturing a wide variety of medical devices for any type of prosthetic surgery (HIP, dental, cranial, maxillofacial) as well as for internal fixation devices (K-Wires or Steinmann Pins). There are a large number of research studies on DMLS, including microstructural characterization, mechanical properties and those based on production quality assurance but the influence of porosity in the corrosion behavior of these materials not been sufficiently considered. In the present paper, surgical pins of Ti6Al4V have been produced by DMLS. After testing in a phosphate buffered saline solution, the surface of the titanium alloy appeared locally covered by a voluminous white oxide. This unexpected behavior was presumably due to the existence of internal defects in the pins as result of the manufacturing process. The importance of these defects-that might act as crevice nucleation sites- has been revealed by electrochemical techniques and confirmed by computed tomography.

  12. Life expectancy of modular Ti6Al4V hip implants: Influence of stress and environment

    DEFF Research Database (Denmark)

    Chandra, A.; Ryu, J.J.; Karra, P.

    2011-01-01

    Stress dependent electrochemical dissolution is identified as one of the key mechanisms governing surface degradation in fretting and crevice corrosion of biomedical implants. The present study focuses on delineating the roles of mechanical stress and chemical conditions on the life expectancy...... of modular hip implants. First, material removal on a stressed surface of Ti6Al4V subjected to single asperity contact is investigated experimentally to identify the influence of contact load, in-plane stress and chemical environment on mean wear rates. A range of known stress levels are applied...... views these scratches as initial notches and utilizes a mixed-mode fatigue crack propagation model to estimate the critical crack length for onset of instability. The number of loading cycles needed to reach this critical crack length is then labeled as the expected life of the implant under given...

  13. Location specific solidification microstructure control in electron beam melting of Ti-6Al-4V

    Energy Technology Data Exchange (ETDEWEB)

    Narra, Sneha P.; Cunningham, Ross; Beuth, Jack; Rollett, Anthony D.

    2018-01-01

    Relationships between prior beta grain size in solidified Ti-6Al-4V and melting process parameters in the Electron Beam Melting (EBM) process are investigated. Samples are built by varying a machine-dependent proprietary speed function to cover the process space. Optical microscopy is used to measure prior beta grain widths and assess the number of prior beta grains present in a melt pool in the raster region of the build. Despite the complicated evolution of beta grain sizes, the beta grain width scales with melt pool width. The resulting understanding of the relationship between primary machine variables and prior beta grain widths is a key step toward enabling the location specific control of as-built microstructure in the EBM process. Control of grain width in separate specimens and within a single specimen is demonstrated.

  14. Effect of microstructure and cutting speed on machining behavior of Ti6Al4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Telrandhe, Sagar V.; Mishra, Sushil; Saxena, Ashish K. [Indian Institute of Technology Bombay, Mumbai (India)

    2017-05-15

    Machining of aerospace and biomedical grade titanium alloys has always been a challenge because of their low conductivity and elastic modulus. Different machining methods and parameters have been adopted for high precision machining of titanium alloys. Machining of titanium alloys can be improved by microstructure optimization. The present study focuses on the effect of microstructure on ma- chinability of Ti6Al4V alloys at different cutting speeds. Samples were subjected to different annealing conditions resulting in different grain sizes and local micro-strains (misorientation). Cutting forces were significantly reduced after annealing; consequently, sub-surface residual stresses were reduced. Deformation twinning was also observed on samples annealed at a higher temperature due to larger grain size. Initial strain free grains and deformation twinning during machining reduces the cutting force at higher cutting speed.

  15. Improved thrombogenicity on oxygen etched Ti6Al4V surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Riedel, Nicholas A. [Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523 (United States); Smith, Barbara S. [School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523 (United States); Williams, John D. [Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523 (United States); Popat, Ketul C., E-mail: ketul.popat@colostate.edu [Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523 (United States); School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523 (United States)

    2012-07-01

    Thrombus formation on blood contacting biomaterials continues to be a key factor in initiating a critical mode of failure in implantable devices, requiring immediate attention. In the interest of evaluating a solution for one of the most widely used biomaterials, titanium and its alloys, this study focuses on the use of a novel surface oxidation treatment to improve the blood compatibility. This study examines the possibility of using oblique angle ion etching to produce a high quality oxide layer that enhances blood compatibility on medical grade titanium alloy Ti6Al4V. An X-ray photoelectron spectroscopy (XPS) analysis of these oxygen-rich surfaces confirmed the presence of TiO{sub 2} peaks and also indicated increased surface oxidation as well as a reduction in surface defects. After 2 h of contact with whole human plasma, the oxygen etched substrates demonstrated a reduction in both platelet adhesion and activation as compared to bare titanium substrates. The whole blood clotting behavior was evaluated for up to 45 min, showing a significant decrease in clot formation on oxygen etched substrates. Finally, a bicinchoninic acid (BCA) total protein assay and XPS were used to evaluate the degree of key blood serum protein (fibrinogen, albumin, immunoglobulin G) adsorption on the substrates. The results showed similar protein levels for both the oxygen etched and control substrates. These results indicate that oblique angle oxygen etching may be a promising method to increase the thrombogenicity of Ti6Al4V. - Highlights: Black-Right-Pointing-Pointer Oblique angle oxygen ion etching creates a high quality, uniform oxide surface. Black-Right-Pointing-Pointer Oxygen etched substrates showed fewer adhered platelets. Black-Right-Pointing-Pointer Platelet activation was reduced by the improved oxide surface. Black-Right-Pointing-Pointer Oxygen etched substrates exhibited increased whole blood clotting times. Black-Right-Pointing-Pointer Although clotting reductions were

  16. Characterization of cellular solids in Ti6Al4V for orthopaedic implant applications: Trabecular titanium.

    Science.gov (United States)

    Marin, E; Fusi, S; Pressacco, M; Paussa, L; Fedrizzi, L

    2010-07-01

    EBM (Electron Beam Melting) technology can be used successfully to obtain cellular solids in metallic biomaterials that can greatly increase osseointegration in arthroprothesis and at the same time maintain good mechanical properties. The investigated structures, called Trabecular Titanium, usually cannot be obtained by traditional machining. Two samples: (A) with a smaller single cell area and, (B) with a bigger single cell area, were produced and studied in this project. They have been completely characterized and compared with the results in similar literature pertinent to Ti6Al4V EBM structures. Relative density was evaluated using different methods, the mean diameter of the open porosities was calculated by Scanning Electron Microscope images; the composition was evaluated using Energy-Dispersive X-Ray Spectroscopy; the microstructure (alpha-beta) was investigated using chemical etching and, the mechanical proprieties were investigated using UMTS. The mean porosity values resulted comparable with spongy bone (63% for A and 72% for B). The mean diameter of the single porosity (650 mum for A and 1400 mum for B) resulted compatible with the osseointegration data from the literature, in particular for sample A. The Vickers micro-hardness tests and the chemical etching demonstrated that the structure is fine, uniform and well distributed. The mechanical test proved that sample (A) was more resistant than sample (B), but sample (B) showed an elastic modulus almost equal to the value of spongy bone. The results of this study suggest that the two Ti6Al4V cellular solids can be used in biomedical applications to promote osseointegration demonstrating that they maybe successfully used in prosthetic implants. Additional implant results will be published in the near future. Copyright 2010 Elsevier Ltd. All rights reserved.

  17. Fatigue of Ti6Al4V Structural Health Monitoring Systems Produced by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Maria Strantza

    2016-02-01

    Full Text Available Selective laser melting (SLM is an additive manufacturing (AM process which is used for producing metallic components. Currently, the integrity of components produced by SLM is in need of improvement due to residual stresses and unknown fracture behavior. Titanium alloys produced by AM are capable candidates for applications in aerospace and industrial fields due to their fracture resistance, fatigue behavior and corrosion resistance. On the other hand, structural health monitoring (SHM system technologies are promising and requested from the industry. SHM systems can monitor the integrity of a structure and during the last decades the research has primarily been influenced by bionic engineering. In that aspect a new philosophy for SHM has been developed: the so-called effective structural health monitoring (eSHM system. The current system uses the design freedom provided by AM. The working principle of the system is based on crack detection by means of a network of capillaries that are integrated in a structure. The main objective of this research is to evaluate the functionality of Ti6Al4V produced by the SLM process in the novel SHM system and to confirm that the eSHM system can successfully detect cracks in SLM components. In this study four-point bending fatigue tests on Ti6Al4V SLM specimens with an integrated SHM system were conducted. Fractographic analysis was performed after the final failure, while finite element simulations were used in order to determine the stress distribution in the capillary region and on the component. It was proven that the SHM system does not influence the crack initiation behavior during fatigue. The results highlight the effectiveness of the eSHM on SLM components, which can potentially be used by industrial and aerospace applications.

  18. Corrosion behavior of Ti and TI6Al4V in citrate buffers containing fluoride ions

    Directory of Open Access Journals (Sweden)

    Anelise Marlene Schmidt

    2010-03-01

    Full Text Available The effect of fluoride ions concentration on the electrochemical behavior of Ti grade 2 and Ti6Al4V in citrate buffers was studied. Open circuit potential (OCP measurements and voltammetric studies of the samples in the fluoride containing citrate buffers revealed a dissolution process when the pH falls below 5.0 and the NaF content is higher than 0.01 M. However, in citrate pH 7.6 the materials showed a passive behavior even in 0.1 M NaF. Some micrographs of Ti grade 2 obtained after longer immersion times in citrate pH 5.0 with 0.01 M NaF showed a surface attack. EIS (Electrochemical Impedance Sprectroscopy data obtained at the OCP revealed that the film resistance decreases when the immersion time is increased in pH 5.0 containing 0.1 M NaF. In the citrate pH 7.6 the EIS data indicated a two-layer model of an oxide film consisting of a more compact inner layer and a porous outer layer. On the other hand, the EIS results in citrate pH 4.0 change significantly when the fluoride ions concentration increases from 0.01 to 0.05 M. The electrochemical data revealed that the corrosion behavior of Ti grade 2 and Ti6Al4V in the citrate buffers depends on the pH, the fluoride content and the exposure time.

  19. Electrochemical analysis of the UV treated bactericidal Ti6Al4V surfaces

    International Nuclear Information System (INIS)

    Pacha-Olivenza, Miguel A.; Gallardo-Moreno, Amparo M.; Vadillo-Rodríguez, Virginia; González-Martín, M. Luisa; Pérez-Giraldo, Ciro; Galván, Juan C.

    2013-01-01

    This research investigates in detail the bactericidal effect exhibited by the surface of the biomaterial Ti6Al4V after being subjected to UV-C light. It has been recently hypothesized that small surface currents, occurring as a consequence of the electron–hole pair recombination taking place after the excitation process, are behind the bactericidal properties displayed by this UV-treated material. To corroborate this hypothesis we have used different electrochemical techniques, such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization plots and Mott–Schottky plots. EIS and Mott–Schottky plots have shown that UV-C treatment causes an initial increase on the surface electrical conduction of this material. In addition, EIS and polarization plots demonstrated that higher corrosion currents occur at the UV treated than at the non-irradiated samples. Despite this increase in the corrosion currents, EIS has also shown that such currents are not likely to affect the good stability of this material oxide film since the irradiated samples completely recovered the control values after being stored in dark conditions for a period not longer than 24 h. These results agree with the already-published in vitro transitory behavior of the bactericidal effect, which was shown to be present at initial times after the biomaterial implantation, a crucial moment to avoid a large number of biomaterial associated infections. Highlights: ► Bactericidal response of UV-treated Ti6Al4V is explained through electrochemistry. ► There is an increase in the superficial electrical conduction after UV-treatment. ► Higher corrosion currents for UV-treated against non-UV-treated samples are shown. ► EIS shows the recuperation on irradiated samples in agreement with microbial tests

  20. Laser metal deposition of Ti6Al4V: A study on the effect of laser power on microstructure and microhardness

    CSIR Research Space (South Africa)

    Mahamood, RM

    2013-03-01

    Full Text Available The effect of laser power on the resulting microstructure and microhardness of laser metal deposited Ti6Al4V powder on Ti6Al4V substrate has been investigated. The tracks were deposited using 99.6 % pure Ti6Al4V powder of particle size ranging...

  1. Study on improved tribological properties by alloying copper to CP-Ti and Ti-6Al-4V alloy.

    Science.gov (United States)

    Wang, Song; Ma, Zheng; Liao, Zhenhua; Song, Jian; Yang, Ke; Liu, Weiqiang

    2015-12-01

    Copper alloying to titanium and its alloys is believed to show an antibacterial performance. However, the tribological properties of Cu alloyed titanium alloys were seldom studied. Ti-5Cu and Ti-6Al-4V-5Cu alloys were fabricated in the present study in order to further study the friction and wear properties of titanium alloys with Cu additive. The microstructure, composition and hardness were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and hardness tester. The tribological behaviors were tested with ZrO2 counterface in 25% bovine serum using a ball-on-disc tribo-tester. The results revealed that precipitations of Ti2Cu intermetallic compounds appeared in both Ti-5Cu and Ti-6Al-4V-5Cu alloys. The tribological results showed an improvement in friction and wear resistance for both Ti-5Cu and Ti-6Al-4V-5Cu alloys due to the precipitation of Ti2Cu. The results also indicated that both CP-Ti and Ti-5Cu behaved better wear resistance than Ti-6Al-4V and Ti-6Al-4V-5Cu due to different wear mechanisms when articulated with hard zirconia. Both CP-Ti and Ti-5Cu revealed dominant adhesive wear with secondary abrasive wear mechanism while both Ti-6Al-4V and Ti-6Al-4V-5Cu showed severe abrasive wear and cracks with secondary adhesive wear mechanism due to different surface hardness integrated by their microstructures and material types. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Surface chemistry of Ti6Al4V components fabricated using selective laser melting for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Vaithilingam, Jayasheelan, E-mail: Jayasheelan.Vaithilingam@nottingham.ac.uk [Additive Manufacturing and 3D Printing Research Group, EPSRC Centre for Innovative Manufacturing in Additive Manufacturing, School of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Prina, Elisabetta [School of Pharmacy, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Goodridge, Ruth D.; Hague, Richard J.M. [Additive Manufacturing and 3D Printing Research Group, EPSRC Centre for Innovative Manufacturing in Additive Manufacturing, School of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Edmondson, Steve [School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Rose, Felicity R.A.J. [School of Pharmacy, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Christie, Steven D.R. [Department of Chemistry, Loughborough University, Loughborough LE11 3TU (United Kingdom)

    2016-10-01

    Selective laser melting (SLM) has previously been shown to be a viable method for fabricating biomedical implants; however, the surface chemistry of SLM fabricated parts is poorly understood. In this study, X-ray photoelectron spectroscopy (XPS) was used to determine the surface chemistries of (a) SLM as-fabricated (SLM-AF) Ti6Al4V and (b) SLM fabricated and mechanically polished (SLM-MP) Ti6Al4V samples and compared with (c) traditionally manufactured (forged) and mechanically polished Ti6Al4V samples. The SLM–AF surface was observed to be porous with an average surface roughness (Ra) of 17.6 ± 3.7 μm. The surface chemistry of the SLM-AF was significantly different to the FGD-MP surface with respect to elemental distribution and their existence on the outermost surface. Sintered particles on the SLM-AF surface were observed to affect depth profiling of the sample due to a shadowing effect during argon ion sputtering. Surface heterogeneity was observed for all three surfaces; however, vanadium was witnessed only on the mechanically polished (SLM-MP and FGD-MP) surfaces. The direct and indirect 3T3 cell cytotoxicity studies revealed that the cells were viable on the SLM fabricated Ti6Al4V parts. The varied surface chemistry of the SLM-AF and SLM-MP did not influence the cell behaviour. - Highlights: • Surface chemistry of selective laser melted (SLM) Ti6Al4V parts was compared with conventionally forged Ti6Al4V parts. • The surface elemental compositions of the SLM as-fabricated surfaces were significantly different to the forged surface. • Surface oxide-layer of the SLM as-fabricated was thicker than the polished SLM surfaces and the forged Ti6Al4V surfaces.

  3. Compressive Strength Evaluation in Brazed ZrO2/Ti6Al4V Joints Using Finite Element Analysis

    Science.gov (United States)

    Sharma, Ashutosh; Kee, Se Ho; Jung, Flora; Heo, Yongku; Jung, Jae Pil

    2016-05-01

    This study aims to synthesize and evaluate the compressive strength of the ZrO2/Ti-6Al-4V joint brazed using an active metal filler Ag-Cu-Sn-Ti, and its application to dental implants assuring its reliability to resist the compressive failure in the actual oral environment. The brazing was performed at a temperature of 750 °C for 30 min in a vacuum furnace under 5 × 10-6 Torr atmosphere. The microstructure of the brazed joint showed the presence of an Ag-rich matrix and a Cu-rich phase, and Cu-Ti intermetallic compounds were observed along the Ti-6Al-4V bonded interface. The compressive strength of the brazed ZrO2/Ti-6Al-4V joint was measured by EN ISO 14801 standard test method. The measured compressive strength of the joint was ~1477 MPa—a value almost five times that of existing dental cements. Finite element analysis also confirmed the high von Mises stress values. The compressive strains in the samples were found concentrated near the Ti-6Al-4V position, matching with the position of the real fractured sample. These results suggest extremely significant compressive strength in ZrO2/Ti-6Al-4V joints using the Ag-Cu-Sn-Ti filler. It is believed that a highly reliable dental implant can be processed and designed using the results of this study.

  4. Effects of hot isostatic pressing temperature on casting shrinkage densification and microstructure of Ti6Al4V alloy

    Directory of Open Access Journals (Sweden)

    Qian Xu

    2017-11-01

    Full Text Available The Ti6Al4V alloy castings were produced by the investment casting process, and the hot isostatic pressing (HIP was used to remove shrinkage from castings. The processing pressure and holding time for HIP were 150 MPa and 20 min, respectively. Four different HIP temperatures were tested, including 750 ºC, 850 ºC, 920 ºC and 950 ºC. To evaluate the effects of temperature on densification and microstructure of Ti6Al4V alloy treated by HIP, non-destructive testing and metallographic observation was performed. The experimental results show that the shrinkage was completely closed at 920 ºC and 950 ºC. The densification of Ti6Al4V alloy increased as the HIP temperature increased below 920 ºC. The lamellae were more uniform, the thickness of lamellae was obviously broadened and the structure was coarsen. Besides, the Norton creep equation was used to simulate the effect of different temperatures on the densification of Ti6Al4V alloy during HIP. The simulation results were in good agreement with the experimental results. It was also found that 920 ºC is a suitable temperature for HIP for Ti6Al4V alloy.

  5. Hydroxyapatite precipitation on nanotubular films formed on Ti-6Al-4V alloy for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Chae-Ik; Jeong, Yong-Hoon [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, and Research Center for Oral Disease Regulation of the Aged, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, and Research Center for Oral Disease Regulation of the Aged, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Brantley, William A. [Division of Restorative, Prosthetic and Primary Care Dentistry, College of Dentistry, The Ohio State, University, Columbus, OH (United States)

    2013-12-31

    In this study, hydroxyapatite precipitation on nanotubular film-formed Ti-6Al-4V alloy for biomedical applications has been investigated using a variety of techniques. To prepare the substrate samples for hydroxyapatite (HA) deposition, the starting Ti-6Al-4V alloy was polished and heat-treated for 12 h at 1050 °C in an Ar atmosphere, followed by water-quenching at 0 °C. Nanotube formation on the titanium alloy was performed using anodization with a DC power supply at 30 V for 1 h in 1 M H{sub 3}PO{sub 4} + 0.8 wt.% NaF at 25 °C. Subsequent HA precipitation treatment was carried out by cyclic voltammetry over a potential range of −1.5 V to 0 V using a scanning rate of 100 mV/s in 0.03 M Ca(NO{sub 3}){sub 2} ∙ 4 H{sub 2}O + 0.018 M NH{sub 4}H{sub 2}PO{sub 4} at 80° ± 1 °C. Four different numbers of cycles were employed: 10, 20, 30, and 50. Surface morphology and structure were examined by field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The heat-treated Ti–6Al–4V alloy has a needle-like duplex microstructure containing the martensitic α′ phase and β phase. Plate-like precipitates were formed on bulk Ti–6Al–4V alloy, and the size of these precipitates increased with the number of deposition cycles. The HA precipitates on the nanotube surface showed a mixture of plate-like and flower-like particles with more deposition cycles. The deposited HA phase in the coated layer had an amorphous structure, with particle composition in good agreement with Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}. - Highlights: • Hydroxyapatite (HA) precipitation on nanotubular films formed on Ti–6Al–4V alloy was investigated using a variety of experimental methods. • HA precipitation treatment was carried out using a cyclic voltammetry method after nanotube formation on Ti–6Al–4V alloy. • Plate-like precipitates were formed on the bulk (not anodized) alloy, and the

  6. Processing of HA-coated Ti-6Al-4V by a ceramic slurry approach: an in vitro study.

    Science.gov (United States)

    Thian, E S; Khor, K A; Loh, N H; Tor, S B

    2001-06-01

    Hydroxyapatite-coated titanium alloy composite powders (Ti-6Al-4V/HA) was produced by a ceramic slurry approach. The aim was to evaluate the stability of the coating when subjected to a physiological medium simulated body fluid (SBF). Three consolidation conditions (700 degrees C for 5 h, 700 degrees C for 8 h and 700 degrees C for 11 h) were used in the production of the Ti-6Al-4V/HA composite powders. Results showed that biodissolution followed by apatite precipitation had taken place after soaking in SBF. In addition, it was found that consolidation at 700 degrees C for 5 h resulted in a weak mechanical locking of calcium phosphate on the Ti-6Al-4V surfaces; and the formation of small crystallites, which would increase the dissolution rate.

  7. Experimental and Numerical Analysis of Injection Molding of Ti-6Al-4V Powders for High-Performance Titanium Parts

    Science.gov (United States)

    Lin, Dongguo; Kang, Tae Gon; Han, Jun Sae; Park, Seong Jin; Chung, Seong Taek; Kwon, Young-Sam

    2018-02-01

    Both experimental and numerical analysis of powder injection molding (PIM) of Ti-6Al-4V alloy were performed to prepare a defect-free high-performance Ti-6Al-4V part with low carbon/oxygen contents. The prepared feedstock was characterized with specific experiments to identify its viscosity, pressure-volume-temperature and thermal properties to simulate its injection molding process. A finite-element-based numerical scheme was employed to simulate the thermomechanical process during the injection molding. In addition, the injection molding, debinding, sintering and hot isostatic pressing processes were performed in sequence to prepare the PIMed parts. With optimized processing conditions, the PIMed Ti-6Al-4V part exhibits excellent physical and mechanical properties, showing a final density of 99.8%, tensile strength of 973 MPa and elongation of 16%.

  8. Friction and wear properties of Ti6Al4V/WC-Co in cold atmospheric plasma jet

    International Nuclear Information System (INIS)

    Xu Wenji; Liu Xin; Song Jinlong; Wu Libo; Sun Jing

    2012-01-01

    Highlights: ► Cold plasma jet can effectively reduce the friction coefficients of Ti6Al4V/WC-Co friction pairs. ► Cold plasma jet can easily form nitrides on the surface of Ti6Al4V and on new surfaces generated by tool wear. ► The nitrides can reduce the friction coefficients and protect the friction surface. - Abstract: The friction and wear properties of Ti6Al4V/WC-Co friction pair were studied using an autonomous atmospheric pressure bare electrode cold plasma jet generating device and block-on-ring friction/wear tester, respectively. The study was conducted under air, air jet, nitrogen jet, air cold plasma jet, and nitrogen cold plasma jet atmospheres. Both nitrogen cold and air cold plasma jets effectively reduced the friction coefficients of the friction pairs and decreased friction temperature. The friction coefficient in the nitrogen cold plasma jet decreased to almost 60% compared with that in the air. The scanning electron microscope, energy-dispersive X-ray spectroscope, and X-ray diffraction analyses illustrated that adhesive wear was relieved and the friction surfaces of Ti6Al4V were smoother, both in the nitrogen cold and air cold plasma jets. The roughness value R a of the Ti6Al4V friction surfaces can reach 1.107 μm. A large number of nitrogen particles in the ionic and excited states contained by cold plasma jets reacts easily on the friction surface to produce a large amount of nitrides, which can excellently reduce the wear of Ti6Al4V/WC-Co friction pairs in real-time.

  9. Optimization of welding parameters of Ti6Al4V alloy using electron beam

    Directory of Open Access Journals (Sweden)

    Petr Havlík

    2016-06-01

    Full Text Available Titanium alloys and their weld joints find wide application, in particular in the aircraft, automotive and chemical industries, because of their outstanding specific strength and corrosion resistance. The high reactivity of these alloys and the strong degradation effect of elements contained in the atmosphere (H, N and O make it necessary for these alloys to be welded in protective atmospheres or in vacuum. From this viewpoint, Electron Beam Welding is an advantageous welding technology, especially in large series production. In the literature, there is sufficient information about the effect of the basic welding parameters, namely accelerating voltage, current and welding speed, on the properties of welded joints. In the paper, the effects of the spot diameter and beam focusing on the penetration depth and the weld shape in the Ti6Al4V alloy are studied. The results obtained are complemented by an analysis of the microstructure and microhardness measurements across the welds.

  10. Cathodic Cage Plasma Nitriding of Ti6Al4V Alloy

    Directory of Open Access Journals (Sweden)

    Maciej OSSOWSKI

    2016-05-01

    Full Text Available Glow discharge nitriding is being used increasingly more often for modifying the properties of titanium and its alloys with the aim to increase their frictional wear resistance, fatigue strength, and, in the case of medical applications, to eliminate the metallosis effect. Unlike PVD methods, ion nitriding ensures the formation of diffusive layers with very good adhesion to the substrate, but which still have some disadvanteges such as the “edge effect” or “hollow cathode effect” which hinders treatment of complex workpieces. The paper compares nitrided layers produced on Ti6Al4V alloy using two different types of nitriding processes. The first process is conventional dc plasma nitriding (DCPN where the samples were placed at the cathode potential, while the second one is a new method of cathodic cage plasma nitriding (CCPN process, where the substrate is insulated from the cathode and anode. The experiments have shown that the treatment conducted in a cathodic cage can be alternative for conventional ion nitriding, especially when used for small parts with complicated shapes used in the space or medical industry. DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7343

  11. Microstructural Evolution in Friction Stir Welding of Ti-6Al-4V

    Science.gov (United States)

    Rubisoff, H.; Querin, J.; Magee, D.; Schneider, J.

    2008-01-01

    Friction stir welding (FSW) is a thermo-mechanical process that utilizes a nonconsumable rotating pin tool to consolidate a weld joint. In the conventional FSW process, the pin tool is responsible for generating both the heat required to soften the material and the forces necessary to deform and combine the weld seam. As such, the geometry of the pin tool is important to the quality of the weld and the process parameters required to produce the weld. Because the geometry of the pin tool is limitless, a reduced set of pin tools was formed to systematically study their effect on the weldment with respect to mechanical properties and resultant microstructure. In this study 0deg, 15deg, 30deg, 45deg, and 60deg tapered, microwave sintered, tungsten carbide (WC) pin tools were used to FSW Ti-6Al-4V. Transverse sections of the weld were used to test for mechanical properties and to document the microstructure using optical microscopy. X-ray diffraction (XRD) was also used to characterize the microstructure in the welds. FSW results for the 45deg and 60deg pin tools are reported in this paper.

  12. Genesis of Microstructures in Friction Stir Welding of Ti-6Al-4V

    Science.gov (United States)

    Tchein, Gnofam Jacques; Jacquin, Dimitri; Coupard, Dominique; Lacoste, Eric; Girot Mata, Franck

    2018-03-01

    This paper is focused on the genesis of microstructures in friction stir welding (FSW) of the Ti-6Al-4V alloy. Several titanium joints, initially prepared with four different preheat treatments, were processed by FSW. Detailed microstructural analyses were performed in order to investigate change in the microstructure during the process. In this work, the FSW processing allows a controlled and stable microstructure to be produced in the stirring zone, regardless of the initial heat treatment or the welding conditions. The welded material undergoes a severe thermomechanical treatment which can be divided into two steps. First, the friction in the shoulder and the plastic strain give rise to the necessary conditions to allow a continuous dynamic recrystallization of the β phase. This operation produces a fine and equiaxed β grain structure. Second, once the pin has moved away, the temperature decreases, and the material undergoes a heat treatment equivalent to air quenching. The material thus exhibits a β → β + α transformation with germination of a fine intergranular Widmanstätten phase within the ex-fully-recrystallized-β grains.

  13. Surface Roughness and Morphology Customization of Additive Manufactured Open Porous Ti6Al4V Structures

    Science.gov (United States)

    Pyka, Grzegorz; Kerckhofs, Greet; Papantoniou, Ioannis; Speirs, Mathew; Schrooten, Jan; Wevers, Martine

    2013-01-01

    Additive manufacturing (AM) is a production method that enables the building of porous structures with a controlled geometry. However, there is a limited control over the final surface of the product. Hence, complementary surface engineering strategies are needed. In this work, design of experiments (DoE) was used to customize post AM surface treatment for 3D selective laser melted Ti6Al4V open porous structures for bone tissue engineering. A two-level three-factor full factorial design was employed to assess the individual and interactive effects of the surface treatment duration and the concentration of the chemical etching solution on the final surface roughness and beam thickness of the treated porous structures. It was observed that the concentration of the surface treatment solution was the most important factor influencing roughness reduction. The designed beam thickness decreased the effectiveness of the surface treatment. In this case study, the optimized processing conditions for AM production and the post-AM surface treatment were defined based on the DoE output and were validated experimentally. This allowed the production of customized 3D porous structures with controlled surface roughness and overall morphological properties, which can assist in more controlled evaluation of the effect of surface roughness on various functional properties. PMID:28788357

  14. New tool holder design for cryogenic machining of Ti6Al4V

    Science.gov (United States)

    Bellin, Marco; Sartori, Stefano; Ghiotti, Andrea; Bruschi, Stefania

    2017-10-01

    The renewed demand of increasing the machinability of the Ti6Al4V titanium alloy to produce biomedical and aerospace parts working at high temperature has recently led to the application of low-temperature coolants instead of conventional cutting fluids to increase both the tool life and the machined surface integrity. In particular, the liquid nitrogen directed to the tool rake face has shown a great capability of reducing the temperature at the chip-tool interface, as well as the chemical interaction between the tool coating and the titanium to be machined, therefore limiting the tool crater wear, and improving, at the same time, the chip breakability. Furthermore, the nitrogen is a safe, non-harmful, non-corrosive, odorless, recyclable, non-polluting and abundant gas, characteristics that further qualify it as an environmental friendly coolant to be applied to machining processes. However, the behavior of the system composed by the tool and the tool holder, exposed to the cryogenics temperatures may represent a critical issue in order to obtain components within the required geometrical tolerances. On this basis, the paper aims at presenting the design of an innovative tool holder installed on a CNC lathe, which includes the cryogenic coolant provision system, and which is able to hinder the part possible distortions due to the liquid nitrogen adduction by stabilizing its dimensions through the use of heating cartridges and appropriate sensors to monitor the temperature evolution of the tool holder.

  15. The effect of cutting parameters on surface integrity in milling TI6AL4V

    Directory of Open Access Journals (Sweden)

    Oosthuizen, Tiaan

    2016-12-01

    Full Text Available The objective of machining performance is to reduce operational costs and to increase the production rate while maintaining or improving the required surface integrity of the machined component. Together with industrial partners, several benchmark titanium components were selected and machined to achieve this. Titanium alloys are used extensively in several industries due to its unique strength-to-weight ratio and corrosion resistance. Its properties, however, also make it susceptible to surface integrity damage during machining operations. The research objectives of this study were to understand the effect of cutting parameters on surface integrity to ensure that machined components are within the required surface quality tolerances. The effect of cutting speed and feed rate on surface roughness, micro-hardness, and the microstructure of the work piece were studied for milling Ti6Al4V. The surface roughness increased with a greater feed rate and a decrease in cutting speed. The maximum micro-hardness was 23 per cent harder than the bulk material. Plastic deformation and grain rotation below the machined surface were found with the rotation of the grain lines in the direction of feed. There was no evidence of subsurface defects for any of the cutting conditions tested.

  16. Modelling and simulation of effect of ultrasonic vibrations on machining of Ti6Al4V.

    Science.gov (United States)

    Patil, Sandip; Joshi, Shashikant; Tewari, Asim; Joshi, Suhas S

    2014-02-01

    The titanium alloys cause high machining heat generation and consequent rapid wear of cutting tool edges during machining. The ultrasonic assisted turning (UAT) has been found to be very effective in machining of various materials; especially in the machining of "difficult-to-cut" material like Ti6Al4V. The present work is a comprehensive study involving 2D FE transient simulation of UAT in DEFORM framework and their experimental characterization. The simulation shows that UAT reduces the stress level on cutting tool during machining as compared to that of in continuous turning (CT) barring the penetration stage, wherein both tools are subjected to identical stress levels. There is a 40-45% reduction in cutting forces and about 48% reduction in cutting temperature in UAT over that of in CT. However, the reduction magnitude reduces with an increase in the cutting speed. The experimental analysis of UAT process shows that the surface roughness in UAT is lower than in CT, and the UATed surfaces have matte finish as against the glossy finish on the CTed surfaces. Microstructural observations of the chips and machined surfaces in both processes reveal that the intensity of thermal softening and shear band formation is reduced in UAT over that of in CT. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Early Stages of Microstructure and Texture Evolution during Beta Annealing of Ti-6Al-4V

    Science.gov (United States)

    Pilchak, A. L.; Sargent, G. A.; Semiatin, S. L.

    2018-03-01

    The early stages of microstructure evolution during annealing of Ti-6Al-4V in the beta phase field were established. For this purpose, a series of short-time heat treatments was performed using sheet samples that had a noticeable degree of alpha-phase microtexture in the as-received condition. Reconstruction of the beta-grain structure from electron-backscatter-diffraction measurements of the room-temperature alpha-phase texture revealed that microstructure evolution at short times was controlled not by general grain growth, but rather by nucleation-and-growth events analogous to discontinuous recrystallization. The nuclei comprised a small subset of beta grains that were highly misoriented relative to those comprising the principal texture component of the beta matrix. From a quantitative standpoint, the transformation kinetics were characterized by an Avrami exponent of approximately unity, thus suggestive of metadynamic recrystallization. The recrystallization process led to the weakening and eventual elimination of the initial beta texture through the growth of a population of highly misoriented grains.

  18. Synthesis and In vitro Evaluation of Electrodeposited Barium Titanate Coating on Ti6Al4V.

    Science.gov (United States)

    Rahmati, Shahram; Basiriani, Mohammad Basir; Rafienia, Mohammad; Yaghini, Jaber; Raeisi, Keyvan

    2016-01-01

    Osseointegration has been the concern of implantology for many years. Researchers have used various ceramic coatings for this purpose; however, piezoelectric ceramics (e.g., barium titanate [BTO]) are a novel field of interest. In this regard, BTO (BaTiO3) coating was fabricated by electrophoretic deposition on Ti6Al4V medical alloy, using sol-gel-synthesized nanometer BTO powder. Structure and morphologies were studied using X-ray diffraction and scanning electron microscopy (SEM), respectively. Bioactivity response of coated samples was evaluated by SEM and inductively coupled plasma (ICP) analysis after immersion in simulated body fluid (SBF). Cell compatibility was also studied via MTT assay and SEM imaging. Results showed homogenous coating with cubic structure and crystallite size of about 41 nm. SEM images indicated apatite formation on the coating after 7 days of SBF immersion, and ICP analysis approved ions concentration decrement in SBF. Cells showed flattened morphology in intimate contact with coating after 7 days of culture. Altogether, coated samples demonstrated appropriate bioactivity and biocompatibility.

  19. Laser Powder Cladding of Ti-6Al-4V α/β Alloy.

    Science.gov (United States)

    Al-Sayed Ali, Samar Reda; Hussein, Abdel Hamid Ahmed; Nofal, Adel Abdel Menam Saleh; Hasseb Elnaby, Salah Elden Ibrahim; Elgazzar, Haytham Abdelrafea; Sabour, Hassan Abdel

    2017-10-15

    Laser cladding process was performed on a commercial Ti-6Al-4V (α + β) titanium alloy by means of tungsten carbide-nickel based alloy powder blend. Nd:YAG laser with a 2.2-KW continuous wave was used with coaxial jet nozzle coupled with a standard powder feeding system. Four-track deposition of a blended powder consisting of 60 wt % tungsten carbide (WC) and 40 wt % NiCrBSi was successfully made on the alloy. The high content of the hard WC particles is intended to enhance the abrasion resistance of the titanium alloy. The goal was to create a uniform distribution of hard WC particles that is crack-free and nonporous to enhance the wear resistance of such alloy. This was achieved by changing the laser cladding parameters to reach the optimum conditions for favorable mechanical properties. The laser cladding samples were subjected to thorough microstructure examinations, microhardness and abrasion tests. Phase identification was obtained by X-ray diffraction (XRD). The obtained results revealed that the best clad layers were achieved at a specific heat input value of 59.5 J·mm -2 . An increase by more than three folds in the microhardness values of the clad layers was achieved and the wear resistance was improved by values reaching 400 times.

  20. Surface roughness of Ti6Al4V after heat treatment evaluated by artificial neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Altug, Mehmet [Inonu Univ., Malataya (Turkey). Dept. of Machine and Metal Technologies; Erdem, Mehmet; Bozkir, Oguz [Inonu Univ., Malataya (Turkey); Ozay, Cetin [Univ. of Firat Elazig (Turkey). Faculty of Tech. Education

    2016-05-01

    The study examines how, using wire electrical discharge machining (WEDM), the microstructural, mechanical and conductivity characteristics of the titanium alloy Ti6Al4V are changed as a result of heat treatment and the effect they have on machinability. Scanning electron microscope (SEM), optical microscope and X-ray diffraction (XRD) examinations were performed to determine various characteristics and additionally related microhardness and conductivity measurements were conducted. L{sub 18} Taquchi test design was performed with three levels and six different parameters to determine the effect of such alterations on its machinability using WEDM and post-processing surface roughness (Ra) values were determined. Micro-changes were ensured successfully by using heat treatments. Results obtained with the optimization technique of artificial neural network (ANN) presented minimum surface roughness. Values obtained by using response surface method along with this equation were completely comparable with those achieved in the experiments. The best surface roughness value was obtained from sample D which had a tempered martensite structure.

  1. Laser Micro Bending Process of Ti6Al4V Square Bar

    Directory of Open Access Journals (Sweden)

    Gang Chen

    2014-06-01

    Full Text Available Laser micro bending process of Ti6Al4V square bar are carried out using a 3D thermo-mechanical finite element analytical model (FEM. The transient temperature fields, displacement fields, stress fields and strain fields are obtained and analyzed. The results show that the bending angel during laser micro bending process is in good agreement with experimental measurements. The effects of process parameters on temperature and deformation are also investigated here. During the bending process the temperature increases with the increase of the laser power and the irradiation time. Radiation of the laser beam yields to a rapid temperature increase at the irradiated surface, which leads to the high temperature gradients between the irradiated surface and the unirradiated surface, which suggest that the mechanism of laser micro bending is the temperature gradient mechanism. The z displacement of forward direction and reverse direction increase when the laser power and irradiation time increase. Laser micro bending process can obtain the larger bending angles reverse to laser beam using higher laser power and shorter irradiation time.

  2. Effect of Alkyl Chain Length on Carboxylic Acid SAMs on Ti-6Al-4V

    Directory of Open Access Journals (Sweden)

    Gavin A. Buckholtz

    2012-07-01

    Full Text Available The formation of methyl-terminated carboxylic acid self-assembled monolayers (SAMs with even numbers of carbons, from eighteen to thirty, was investigated on the oxide surface of Ti-6Al-4V and component metal oxides. Modified surfaces were characterized using diffuse reflectance infrared Fourier transform spectroscopy (DRIFT, matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS and contact angle analysis. Infrared spectroscopy indicated that using aerosol spray deposition techniques, stable, all-trans SAMs of octacosanoic (28 carbons and triacontanoic (30 carbons acids were formed on the alloy. Films were similarly formed on titanium and aluminum oxide. The surface of vanadium oxide exhibited limited reactivity. MALDI-TOF MS confirmed that formed films were monolayers, without multilayers or aggregates present. Water contact angles are indicative of the presence of hydrophobic methyl groups at the interface. This stable carboxylic acid SAM formation could be a useful alternative to phosphonic acid SAMs for corrosion and other applications.

  3. Numerical Simulation and Superplastic Forming of Ti-6Al-4V Alloy for a Dental Prosthesis

    Science.gov (United States)

    Li, Xiaomei; Soo, Steven

    2011-04-01

    This article investigates superplastic forming (SPF) technique in conjunction with finite element (FE) simulation applied to dental repair. The superplasticity of Ti-6Al-4V alloys has been studied using a uniquely designed five-hole test with the aim of obtaining the modeled grain size and the flow stress parameters. The data from the five-hole test are subsequently put into the FE program for the simulation of a partial upper denture dental prosthesis (PUD4). The FE simulation of the PUD4 is carried out to set up appropriate input parameters for pressing due to the SPF process being fully automatic controlled. A variety of strain rates ranging from 2.4 × 10-5 to 1 × 10-3 s-1 are selected for the characterization of superplastic properties of the alloy. The Superflag FE program is used to generate an appropriate pressure-time profile and provide information on thickness, grain size, and grain growth rate distribution. Both membrane elements and solid elements have been adopted in the simulation and the results from both types of elements are compared. An evaluation of predicted parameters for the SPF of the prosthesis is presented.

  4. Artificial neural network modeling for evaluating of epitaxial growth of Ti6Al4V weldment

    Energy Technology Data Exchange (ETDEWEB)

    Karimzadeh, F. [Isfahan University of Technology, Isfahan (Iran, Islamic Republic of)]. E-mail: karimzadeh_f@cc.iut.ac.ir; Ebnonnasir, A. [Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Foroughi, A. [Sharif University of Technology, Tehran (Iran, Islamic Republic of)

    2006-09-25

    The effect of epitaxial growth on microstructure of Ti-6Al-4V alloy weldment was examined by artificial neural networks (ANNs). The microplasma arc welding (MPAW) procedure was performed at different currents, welding speeds and flow rates of shielding and plasma gas. Microstructural characterizations were studied by optical and scanning electron microscopy (SEM). Finally, an artificial neural network was developed to predict grain size of fusion zone (FZ) at different currents and welding speeds. The results showed that a coarse primary {beta} phase develops in the fusion zone as a result of epitaxial nucleation on coarsened {beta} grains near the heat affected zone (NHAZ) which grow competitively into the molten weld pool. Based on ANNs analyses, a map of current and welding speed for {alpha} {sup {yields}} {beta} transformation in the HAZ can be constructed. For a lower energy input, grain growth of {beta} phase in the HAZ could be restricted by {alpha} phase. The presence of small quantities of this phase at high peak temperatures in the weld cycle is sufficient to prevent the grain growth of {beta} phase in HAZ and FZ.

  5. Residual stress prediction in a powder bed fusion manufactured Ti6Al4V hip stem

    Science.gov (United States)

    Barrett, Richard A.; Etienne, Titouan; Duddy, Cormac; Harrison, Noel M.

    2017-10-01

    Powder bed fusion (PBF) is a category of additive manufacturing (AM) that is particularly suitable for the production of 3D metallic components. In PBF, only material in the current build layer is at the required melt temperature, with the previously melted and solidified layers reducing in temperature, thus generating a significant thermal gradient within the metallic component, particularly for laser based PBF components. The internal thermal stresses are subsequently relieved in a post-processing heat-treatment step. Failure to adequately remove these stresses can result in cracking and component failure. A prototype hip stem was manufactured from Ti6Al4V via laser PBF but was found to have fractured during over-seas shipping. This study examines the evolution of thermal stresses during the laser PBF manufacturing and heat treatment processes of the hip stem in a 2D finite element analysis (FEA) and compares it to an electron beam PBF process. A custom written script for the automatic conversion of a gross geometry finite element model into a thin layer- by-layer finite element model was developed. The build process, heat treatment (for laser PBF) and the subsequent cooling were simulated at the component level. The results demonstrate the effectiveness of the heat treatment in reducing PBF induced thermal stresses, and the concentration of stresses in the region that fractured.

  6. Mechanical Behavior of a Low-Cost Ti-6Al-4V Alloy

    Science.gov (United States)

    Casem, D. T.; Weerasooriya, T.; Walter, T. R.

    2018-01-01

    Mechanical compression tests were performed on an economical Ti-6Al-4V alloy over a range of strain-rates and temperatures. Low rate experiments (0.001-0.1/s) were performed with a servo-hydraulic load frame and high rate experiments (1000-80,000/s) were performed with the Kolsky bar (Split Hopkinson pressure bar). Emphasis is placed on the large strain, high-rate, and high temperature behavior of the material in an effort to develop a predictive capability for adiabatic shear bands. Quasi-isothermal experiments were performed with the Kolsky bar to determine the large strain response at elevated rates, and bars with small diameters (1.59 mm and 794 µm, instrumented optically) were used to study the response at the higher strain-rates. Experiments were also conducted at temperatures ranging from 81 to 673 K. Two constitutive models are used to represent the data. The first is the Zerilli-Armstrong recovery strain model and the second is a modified Johnson-Cook model which uses the recovery strain term from the Zerilli-Armstrong model. In both cases, the recovery strain feature is critical for capturing the instability that precedes localization.

  7. Analysis of Microstructure and Chip Formation When Machining Ti-6Al-4V

    Directory of Open Access Journals (Sweden)

    Islam Shyha

    2018-03-01

    Full Text Available Microstructure and chip formation were evaluated during the step shoulder down-milling of Ti-6Al-4V using a water-miscible vegetable oil-based cutting fluid. Experiments were conducted using the Cut-list fluid supply system previous developed by the authors and a conventional cutting fluid supply system. A thin plastically deformed layer below the machined surface was observed during the metallurgical investigation of the surfaces produced using both systems. Despite noticeable reductions in cutting fluid consumption achieved by Cut-list, no significant disparity was found in microstructural damage. The microstructure of the machined surfaces was strongly affected by cutting speed and fluid flow rate with a discontinuous serrated chip being the principal type. However, increases in cutting fluid flow rate associated with increased cutting speed significantly changed chip morphology where average distance between chip segments increased with cutting speed. Cut-list produced smaller saw-tooth height and larger segmented width, while the transition from aperiodic to periodic serrated chip formation was governed by cutting speed and feed rate. Chip segmentation frequency and shear angle were also sensitive to cutting speed.

  8. Surface Roughness and Morphology Customization of Additive Manufactured Open Porous Ti6Al4V Structures

    Directory of Open Access Journals (Sweden)

    Martine Wevers

    2013-10-01

    Full Text Available Additive manufacturing (AM is a production method that enables the building of porous structures with a controlled geometry. However, there is a limited control over the final surface of the product. Hence, complementary surface engineering strategies are needed. In this work, design of experiments (DoE was used to customize post AM surface treatment for 3D selective laser melted Ti6Al4V open porous structures for bone tissue engineering. A two-level three-factor full factorial design was employed to assess the individual and interactive effects of the surface treatment duration and the concentration of the chemical etching solution on the final surface roughness and beam thickness of the treated porous structures. It was observed that the concentration of the surface treatment solution was the most important factor influencing roughness reduction. The designed beam thickness decreased the effectiveness of the surface treatment. In this case study, the optimized processing conditions for AM production and the post-AM surface treatment were defined based on the DoE output and were validated experimentally. This allowed the production of customized 3D porous structures with controlled surface roughness and overall morphological properties, which can assist in more controlled evaluation of the effect of surface roughness on various functional properties.

  9. Process Optimization and Microstructure Characterization of Ti6Al4V Manufactured by Selective Laser Melting

    Science.gov (United States)

    junfeng, Li; zhengying, Wei

    2017-11-01

    Process optimization and microstructure characterization of Ti6Al4V manufactured by selective laser melting (SLM) were investigated in this article. The relative density of sampled fabricated by SLM is influenced by the main process parameters, including laser power, scan speed and hatch distance. The volume energy density (VED) was defined to account for the combined effect of the main process parameters on the relative density. The results shown that the relative density changed with the change of VED and the optimized process interval is 55˜60J/mm3. Furthermore, compared with laser power, scan speed and hatch distance by taguchi method, it was found that the scan speed had the greatest effect on the relative density. Compared with the microstructure of the cross-section of the specimen at different scanning speeds, it was found that the microstructures at different speeds had similar characteristics, all of them were needle-like martensite distributed in the β matrix, but with the increase of scanning speed, the microstructure is finer and the lower scan speed leads to coarsening of the microstructure.

  10. Multilinear stress-strain and failure calibrations for Ti-6Al-4V.

    Energy Technology Data Exchange (ETDEWEB)

    Corona, Edmundo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2018-02-01

    This memo concerns calibration of an elastic-plastic J2 material model for Ti-6Al-4V (grade 5) alloy based on tensile uniaxial stress-strain data obtained in the laboratory. In addition, tension tests on notched specimens provided data to calibrate two ductile failure models: Johnson-Cook and Wellman's tearing parameter. The tests were conducted by Kim Haulen- beek and Dave Johnson (1528) in the Structural Mechanics Laboratory (SML) during late March and early April, 2017. The SML EWP number was 4162. The stock material was a TIMETALR® 6-4 Titanium billet with 9 in. by 9 in. square section and length of 137 in. The product description indicates that it was a forging delivered in annealed condition (2 hours @ 1300oF, AC at the mill). The tensile mechanical properties reported in the material certi cation are given in Table 1, where σo represents the 0.2% strain offset yield stress, σu the ultimate stress, εf the elongation at failure and R.A. the reduction in area.

  11. Parametric effects of turning Ti-6Al-4V alloys with aluminum oxide nanolubricants with SDBS

    Science.gov (United States)

    Ali, M. A. M.; Azmi, A. I.; Khalil, A. N. M.

    2017-09-01

    Applications of nanolubricants have been claimed to improve machinability of aerospace metals due to reduction of friction as a results of the rolling action of billions of nanoparticles at the tool-chip interface. In addition, the need to pursue for an eco-friendly machining has pushed researchers toward implementing alternative lubrication methods through minimal quantity lubrication (MQL). However, the gap in the current literature regarding the performance of nanolubricants via MQL has restricted the widespread use of this lubricant and technique in industries. The present work aims to understand the parametric effects of nanoparticles concentration, cutting speed, feed rate and nozzle angle during machining of titanium alloy, Ti-6AL-4V. Multiple performance of machinability outputs such as surface roughness, tool wear and power consumption were simultaneously determined via Taguchi orthogonal array and grey relational analyses. Prior to machining tests, the nanolubricants stabilities were investigated through the addition of surfactant; sodium dodecyl benzene sulfonate (SDBS). The results clearly indicated that inclusion of SDBS surfactant managed to reduce agglomeration in the base lubricant. Meanwhile, grey relational analyses revealed that the combination of 0.6 % nanoparticles concentration, cutting speed of 85 m/min, feed rate of 0.1 mm/rev and nozzle angle of 60o as desired setting for all the three machining outputs.

  12. Cavitation during hot tension testing of Ti-6Al-4V

    International Nuclear Information System (INIS)

    Semiatin, S.L.; Ghosh, A.K.; Shell, E.B.; Simon, M.P.

    1998-01-01

    Cavity initiation, growth, and coalescence phenomena during the hot tension testing of Ti-6Al-4V with several different transformed β-microstructures were established to obtain an understanding of the failure process during subtransus hot working. Samples with either a colony-type microstructure (containing grain-boundary α) or a martensitic, acicular α-microstructure were pulled to failure at strain rates between 0.01 and 3 s -1 and various subtransus temperatures ranging from 540 to 955 C. Metallographic analysis of sectioned tension samples with colony microstructures revealed that cavity initiation occurred at very low strains (< or∼0.2) irrespective of strain rate at temperatures below 900 C due to an apparent incompatibility of deformation between the grain-boundary α-layer and the Widmanstatten side plates. Initiation strains were somewhat higher (∝0.2-0.5) for samples with the acicular α-microstructure tested at temperatures below 900 C; however, failure was still intergranular. Subsequent cavity growth was more rapid for colony microstructures than that for the martensitic α-microstructure at these temperatures. Above 900 C, however, substantially higher cavity initiation strains and lower cavity growth rates were obtained for both microstructures. These latter behaviors were ascribed to the presence of a large volume fraction of ductile β-phase and moderate values of the strain-rate sensitivity of the flow stress, respectively. (orig.)

  13. Laser Powder Cladding of Ti-6Al-4V α/β Alloy

    Directory of Open Access Journals (Sweden)

    Samar Reda Al-Sayed Ali

    2017-10-01

    Full Text Available Laser cladding process was performed on a commercial Ti-6Al-4V (α + β titanium alloy by means of tungsten carbide-nickel based alloy powder blend. Nd:YAG laser with a 2.2-KW continuous wave was used with coaxial jet nozzle coupled with a standard powder feeding system. Four-track deposition of a blended powder consisting of 60 wt % tungsten carbide (WC and 40 wt % NiCrBSi was successfully made on the alloy. The high content of the hard WC particles is intended to enhance the abrasion resistance of the titanium alloy. The goal was to create a uniform distribution of hard WC particles that is crack-free and nonporous to enhance the wear resistance of such alloy. This was achieved by changing the laser cladding parameters to reach the optimum conditions for favorable mechanical properties. The laser cladding samples were subjected to thorough microstructure examinations, microhardness and abrasion tests. Phase identification was obtained by X-ray diffraction (XRD. The obtained results revealed that the best clad layers were achieved at a specific heat input value of 59.5 J·mm−2. An increase by more than three folds in the microhardness values of the clad layers was achieved and the wear resistance was improved by values reaching 400 times.

  14. Properties of ion implanted Ti-6Al-4V processed using beamline and PSII techniques

    International Nuclear Information System (INIS)

    Walter, K.C.; Woodring, J.S.; Nastasi, M.; Munson, C.M.; Williams, J.M.; Poker, D.B.

    1996-01-01

    The surface of Ti-6Al-4V (Ti64) alloy has been modified using beamline implantation of boron. In separate experiments, Ti64 has been implanted with nitrogen using a plasma source ion implantation (PSII) technique utilizing either ammonia (NH 3 ), nitrogen (N 2 ), or their combinations as the source of nitrogen ions. Beamline experiments have shown the hardness of the N-implanted surface saturates at a dose level of ∼ 4 x 10 17 at/cm 2 at ∼ 10 GPa. The present work makes comparisons of hardness and tribological tests of (1) B implantation using beamline techniques, and (2) N implanted samples using ammonia and/or nitrogen gas in a PSII process. The results show that PSII using N 2 or NH 3 gives similar hardness as N implantation using a beamline process. The presence of H in the Ti alloy surface does not affect the hardness of the implanted surface. Boron implantation increased the surface hardness by as much as 2.5x at the highest dose level. Wear testing by a pin-on-disk method indicated that nitrogen implantation reduced the wear rate by as much as 120x, and boron implantation reduced the wear rate by 6.5x. Increased wear resistance was accompanied by a decreased coefficient of friction

  15. Fatigue limit estimation of titanium alloy Ti-6Al-4V with infrared thermography

    Science.gov (United States)

    Akai, Atsushi; Shiozawa, Daiki; Sakagami, Takahide

    2017-05-01

    Fatigue limit estimation using infrared thermography has recently received attention as a method for reducing the time required for product design. In this study, the applicability of a method based on mean temperature and dissipated energy measurements was experimentally investigated on a titanium alloy; fatigue plate specimens were fabricated from the titanium alloy Ti-6Al-4V ELI. The fatigue limit of these specimens obtained from conventional fatigue testing was found to be 620 MPa. The estimated fatigue limit obtained from mean temperature measurements was found to be 600 MPa, although estimating the fatigue limit using dissipated energy measurements was difficult because little significant change in dissipated energy values with the stress amplitude was observed. These tendencies are probably attributed to the crystal structure displaying different deformation properties and high vibration absorption properties. The resonance components from the fatigue testing instruments (noise components) were calculated from the frequency analysis of the time-series temperature fluctuation data measured by infrared thermography. The increase in the dissipated energy values (with the noise components subtracted) against the stress amplitude changed at a certain stress amplitude and the fatigue limit could be estimated to be 565 MPa. Therefore, the relative error between the fatigue limit value obtained from conventional fatigue testing and the estimated values was within 10%. The fatigue limit could be estimated more accurately by considering the influence of different deformation properties between tensile and compressive loading due to the crystal structure differences in the dissipated energy measurement.

  16. Effects of Oxygen Content on Tensile and Fatigue Performance of Ti-6Al-4 V Manufactured by Selective Laser Melting

    Science.gov (United States)

    Quintana, Oscar A.; Tong, Weidong

    2017-12-01

    We investigated the selective laser melting (SLM) process for development of Ti-6Al-4 V solid material with oxygen content corresponding to the extra low interstitial (ELI) and non-ELI conditions. The microstructure, chemistry, and tensile properties of samples in as-built and hot isostatically pressed (HIPed) condition were evaluated for both material types, while fatigue performance was evaluated by rotating bending fatigue tests on both smooth and notched SLM ELI and non-ELI Ti-6Al-4 V samples in HIPed condition.

  17. Laser Surface Modification of Ti6Al4V-Cu for Improved Microhardness and Wear Resistance Properties

    OpenAIRE

    Erinosho, Mutiu Folorunsho; Akinlabi, Esther Titilayo; Pityana, Sisa; Owolabi, Gbadebo

    2017-01-01

    To modify the properties of Ti6Al4V alloy, Cu has been added to host an antimicrobial effect in the revised alloy for marine application. The Laser Metal Deposition (LMD) process on the Ti6Al4V alloy and Cu was been investigated for surface modification in order to combat the problem of biofouling in the marine industry. The investigations focused on the microstructural observations, micro-hardness measurements and dry sliding wear in the presence of 3 and 5 weight percents of Cu. The microst...

  18. Tribological characterization of zirconia coatings deposited on Ti6Al4V components for orthopedic applications.

    Science.gov (United States)

    Berni, M; Lopomo, N; Marchiori, G; Gambardella, A; Boi, M; Bianchi, M; Visani, A; Pavan, P; Russo, A; Marcacci, M

    2016-05-01

    One of the most important issues leading to the failure of total joint arthroplasty is related to the wear of the plastic components, which are generally made of ultra high molecular weight polyethylene (UHMWPE). Therefore, the reduction of joint wear represents one of the main challenges the research in orthopedics is called to address nowadays. Surface treatments and coatings have been recognized as innovative methods to improve tribological properties, also in the orthopedic field. This work investigated the possibility to realize hard ceramic coatings on the metal component of a prosthesis, by means of Pulsed Plasma Deposition, in order to reduce friction and wear in the standard coupling against UHMWPE. Ti6Al4V substrates were coated with a 2 μm thick yttria-stabilized zirconia (YSZ) layer. The mechanical properties of the YSZ coatings were assessed by nanoindentation tests performed on flat Ti6Al4V substrates. Tribological performance was evaluated using a ball-on-disk tribometer in dry and lubricated (i.e. with fetal bovine serum) highly-stressing conditions, up to an overall distance of 10 km. Tribology was characterized in terms of coefficient of friction (CoF) and wear rate of the UHMWPE disk. After testing, specimens were analyzed through optical microscopy and SEM images, in order to check the wear degradation mechanisms. Progressive loading scratch tests were also performed in dry and wet conditions to determine the effects of the environment on the adhesion of the coating. Our results supported the beneficial effect of YSZ coating on metal components. In particular, the proposed solution significantly reduced UHMWPE wear rate and friction. At 10 km of sliding distance, a wear rate reduction of about 18% in dry configuration and of 4% in presence of serum, was obtained by the coated group compared to the uncoated group. As far as friction in dry condition is concerned, the coating allowed to maintain low CoF values until the end of the tests, with an

  19. Thermally oxidized titania nanotubes enhance the corrosion resistance of Ti6Al4V.

    Science.gov (United States)

    Grotberg, John; Hamlekhan, Azhang; Butt, Arman; Patel, Sweetu; Royhman, Dmitry; Shokuhfar, Tolou; Sukotjo, Cortino; Takoudis, Christos; Mathew, Mathew T

    2016-02-01

    The negative impact of in vivo corrosion of metallic biomedical implants remains a complex problem in the medical field. We aimed to determine the effects of electrochemical anodization (60V, 2h) and thermal oxidation (600°C) on the corrosive behavior of Ti-6Al-4V, with serum proteins, at physiological temperature. Anodization produced a mixture of anatase and amorphous TiO2 nanopores and nanotubes, while the annealing process yielded an anatase/rutile mixture of TiO2 nanopores and nanotubes. The surface area was analyzed by the Brunauer-Emmett-Teller method and was estimated to be 3 orders of magnitude higher than that of polished control samples. Corrosion resistance was evaluated on the parameters of open circuit potential, corrosion potential, corrosion current density, passivation current density, polarization resistance and equivalent circuit modeling. Samples both anodized and thermally oxidized exhibited shifts of open circuit potential and corrosion potential in the noble direction, indicating a more stable nanoporous/nanotube layer, as well as lower corrosion current densities and passivation current densities than the smooth control. They also showed increased polarization resistance and diffusion limited charge transfer within the bulk oxide layer. The treatment groups studied can be ordered from greatest corrosion resistance to least as Anodized+Thermally Oxidized > Anodized > Smooth > Thermally Oxidized for the conditions investigated. This study concludes that anodized surface has a potential to prevent long term implant failure due to corrosion in a complex in-vivo environment. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Thermal Stability of Residual Stresses in Ti-6Al-4V components

    International Nuclear Information System (INIS)

    Stanojevic, A; Angerer, P; Oberwinkler, B

    2016-01-01

    The need for light weight design while maintaining a high safety is essential for many components, especially in the aircraft industry. Therefore, it's important to consider every aspect to reduce weight, improve fatigue life and maintain safety of crucial components. Residual stresses are a major factor which can positively influence components and fulfil all three requirements. However, due to the inconstancy of the behaviour of residual stresses during the life time of a component, residual stresses are often neglected. If the behaviour of residual stresses could be described reliably over the entire life time of a component, residual stresses could be taken into account and components could be optimized even further. Mechanical and thermal loads are the main reason for relaxation of residual stresses. This work covers the thermal stability of residual stresses in Ti-6Al-4V components. Therefore, exposure tests at raised temperatures were performed on specimens with different surface conditions. Residual stresses were measured by x-ray diffraction before and after testing. Creep tests were also carried out to describe the creep behaviour and thereby the ability for residual stress relaxation. A correlation between the creep rate and amount of relaxed stress was found. The creep behaviour of the material was described by using a combination of the Norton Power law and the Arrhenius equation. The Zener-Wert-Avrami model was used to describe the residual stress relaxation. With these models a satisfying correlation between measured and calculated data was found. Hence, the relaxation of residual stresses due to thermal load was described reliably. (paper)

  1. Thermoelectric assessment of laser peening induced effects on a metallic biomaterial Ti6Al4V

    Science.gov (United States)

    Carreón, H.; Barriuso, S.; Porro, J. A.; González-Carrasco, J. L.; Ocaña, J. L.

    2014-03-01

    Laser peening has recently emerged as a useful technique to overcome detrimental effects associated to another wellknown surface modification processes such as shot peening or grit blasting used in the biomedical field. It is worth to notice that besides the primary residual stress effect, thermally induced effects might also cause subtle surface and subsurface microstructural changes that might influence corrosion resistance. Moreover, since maximum loads use to occur at the surface, they could also play a critical role in the fatigue strength. In this work, plates of Ti-6Al-4V alloy of 7 mm in thickness were modified by laser peening without using a sacrificial outer layer. Irradiation by a Q-switched Nd-YAG laser (9.4 ns pulse length) working in fundamental harmonic at 2.8 J/pulse and with water as confining medium was used. Laser pulses with a 1.5 mm diameter at an equivalent overlapping density (EOD) of 5000 cm-2 were applied. Attempts to analyze the global induced effects after laser peening were addressed by using the contacting and non-contacting thermoelectric power (TEP) techniques. It was demonstrated that the thermoelectric method is entirely insensitive to surface topography while it is uniquely sensitive to subtle variations in thermoelectric properties, which are associated with the different material effects induced by different surface modification treatments. These results indicate that the stress-dependence of the thermoelectric power in metals produces sufficient contrast to detect and quantitatively characterize regions under compressive residual stress based on their thermoelectric power contrast with respect to the surrounding intact material. However, further research is needed to better separate residual stress effects from secondary material effects, especially in the case of low-conductivity engineering materials like titanium alloys.

  2. Performance of High Layer Thickness in Selective Laser Melting of Ti6Al4V.

    Science.gov (United States)

    Shi, Xuezhi; Ma, Shuyuan; Liu, Changmeng; Chen, Cheng; Wu, Qianru; Chen, Xianping; Lu, Jiping

    2016-12-01

    To increase building rate and save cost, the selective laser melting (SLM) of Ti6Al4V with a high layer thickness (200 μm) and low cost coarse powders (53 μm-106 μm) at a laser power of 400 W is investigated in this preliminary study. A relatively large laser beam with a diameter of 200 μm is utilized to produce a stable melt pool at high layer thickness, and the appropriate scanning track, which has a smooth surface with a shallow contact angle, can be obtained at the scanning speeds from 40 mm/s to 80 mm/s. By adjusting the hatch spacings, the density of multi-layer samples can be up to 99.99%, which is much higher than that achieved in previous studies about high layer thickness selective laser melting. Meanwhile, the building rate can be up to 7.2 mm³/s, which is about 2 times-9 times that of the commercial equipment. Besides, two kinds of defects are observed: the large un-melted defects and the small spherical micropores. The formation of the un-melted defects is mainly attributed to the inappropriate overlap rates and the unstable scanning tracks, which can be eliminated by adjusting the processing parameters. Nevertheless, the micropores cannot be completely eliminated. It is worth noting that the high layer thickness plays a key role on surface roughness rather than tensile properties during the SLM process. Although a sample with a relatively coarse surface is generated, the average values of yield strength, ultimate tensile strength, and elongation are 1050 MPa, 1140 MPa, and 7.03%, respectively, which are not obviously different than those with the thin layer thickness used in previous research; this is due to the similar metallurgical bonding and microstructure.

  3. Performance of High Layer Thickness in Selective Laser Melting of Ti6Al4V

    Directory of Open Access Journals (Sweden)

    Xuezhi Shi

    2016-12-01

    Full Text Available To increase building rate and save cost, the selective laser melting (SLM of Ti6Al4V with a high layer thickness (200 μm and low cost coarse powders (53 μm–106 μm at a laser power of 400 W is investigated in this preliminary study. A relatively large laser beam with a diameter of 200 μm is utilized to produce a stable melt pool at high layer thickness, and the appropriate scanning track, which has a smooth surface with a shallow contact angle, can be obtained at the scanning speeds from 40 mm/s to 80 mm/s. By adjusting the hatch spacings, the density of multi-layer samples can be up to 99.99%, which is much higher than that achieved in previous studies about high layer thickness selective laser melting. Meanwhile, the building rate can be up to 7.2 mm3/s, which is about 2 times–9 times that of the commercial equipment. Besides, two kinds of defects are observed: the large un-melted defects and the small spherical micropores. The formation of the un-melted defects is mainly attributed to the inappropriate overlap rates and the unstable scanning tracks, which can be eliminated by adjusting the processing parameters. Nevertheless, the micropores cannot be completely eliminated. It is worth noting that the high layer thickness plays a key role on surface roughness rather than tensile properties during the SLM process. Although a sample with a relatively coarse surface is generated, the average values of yield strength, ultimate tensile strength, and elongation are 1050 MPa, 1140 MPa, and 7.03%, respectively, which are not obviously different than those with the thin layer thickness used in previous research; this is due to the similar metallurgical bonding and microstructure.

  4. Porous Ti6Al4V scaffold directly fabricating by rapid prototyping: preparation and in vitro experiment

    NARCIS (Netherlands)

    Li Jiaping, L.; de Wijn, J.R.; van Blitterswijk, Clemens; de Groot, K.

    2006-01-01

    Three-dimensional (3D) fiber deposition (3DF), a rapid prototyping technology, was successfully directly applied to produce novel 3D porous Ti6Al4V scaffolds with fully interconnected porous networks and highly controllable porosity and pore size. A key feature of this technology is the 3D

  5. A comparative study on the sintering and casting of a blended elemental Ti-6Al-4V alloy

    CSIR Research Space (South Africa)

    Masikane, M

    2015-07-01

    Full Text Available and chemical composition are sometimes reported for PM parts. This work compares properties of a blended elemental Ti-6Al-4V alloy obtained by sintering under argon gas atmosphere with those of a vacuum cast alloy. Argon was purified by passing it through a...

  6. Selective Laser Melting Produced Ti-6Al-4V: Post-Process Heat Treatments to Achieve Superior Tensile Properties

    Directory of Open Access Journals (Sweden)

    Gerrit M. Ter Haar

    2018-01-01

    Full Text Available Current post-process heat treatments applied to selective laser melting produced Ti-6Al-4V do not achieve the same microstructure and therefore superior tensile behaviour of thermomechanical processed wrought Ti-6Al-4V. Due to the growing demand for selective laser melting produced parts in industry, research and development towards improved mechanical properties is ongoing. This study is aimed at developing post-process annealing strategies to improve tensile behaviour of selective laser melting produced Ti-6Al-4V parts. Optical and electron microscopy was used to study α grain morphology as a function of annealing temperature, hold time and cooling rate. Quasi-static uniaxial tensile tests were used to measure tensile behaviour of different annealed parts. It was found that elongated α’/α grains can be fragmented into equiaxial grains through applying a high temperature annealing strategy. It is shown that bi-modal microstructures achieve a superior tensile ductility to current heat treated selective laser melting produced Ti-6Al-4V samples.

  7. A Review of the As-Built SLM Ti-6Al-4V Mechanical Properties towards Achieving Fatigue Resistant Designs

    Directory of Open Access Journals (Sweden)

    Dylan Agius

    2018-01-01

    Full Text Available Ti-6Al-4V has been widely used in both the biomedical and aerospace industry, due to its high strength, corrosion resistance, high fracture toughness and light weight. Additive manufacturing (AM is an attractive method of Ti-6Al-4V parts’ fabrication, as it provides a low waste alternative for complex geometries. With continued progress being made in SLM technology, the influence of build layers, grain boundaries and defects can be combined to improve further the design process and allow the fabrication of components with improved static and fatigue strength in critical loading directions. To initiate this possibility, the mechanical properties, including monotonic, low and high cycle fatigue and fracture mechanical behaviour, of machined as-built SLM Ti-6Al-4V, have been critically reviewed in order to inform the research community. The corresponding crystallographic phases, defects and layer orientations have been analysed to determine the influence of these features on the mechanical behaviour. This review paper intends to enhance our understanding of how these features can be manipulated and utilised to improve the fatigue resistance of components fabricated from Ti-6Al-4V using the SLM technology.

  8. Effect of powder density variation on premixed Ti-6Al-4 V and Cu composites during laser metal deposition

    CSIR Research Space (South Africa)

    Erinosho, MF

    2016-05-01

    Full Text Available This paper reports the effect of powder density variation on the premixed Ti-6Al-4 V/Cu and Ti-6A-4 V/2Cu Composites. Two sets of experiment were conducted in this study. Five deposits each were made for the two premixed composites. Laser powers were...

  9. Biocompatibility and Corrosion Protection Behaviour of Hydroxyapatite Sol-Gel-Derived Coatings on Ti6Al4V Alloy.

    Science.gov (United States)

    El Hadad, Amir A; Peón, Eduardo; García-Galván, Federico R; Barranco, Violeta; Parra, Juan; Jiménez-Morales, Antonia; Galván, Juan Carlos

    2017-01-24

    The aim of this work was to prepare hydroxyapatite coatings (HAp) by a sol-gel method on Ti6Al4V alloy and to study the bioactivity, biocompatibility and corrosion protection behaviour of these coatings in presence of simulated body fluids (SBFs). Thermogravimetric/Differential Thermal Analyses (TG/DTA) and X-ray Diffraction (XRD) have been applied to obtain information about the phase transformations, mass loss, identification of the phases developed, crystallite size and degree of crystallinity of the obtained HAp powders. Fourier Transformer Infrared Spectroscopy (FTIR) has been utilized for studying the functional groups of the prepared structures. The surface morphology of the resulting HAp coatings was studied by Scanning Electron Microscopy (SEM). The bioactivity was evaluated by soaking the HAp-coatings/Ti6Al4V system in Kokubo's Simulated Body Fluid (SBF) applying Inductively Coupled Plasma (ICP) spectrometry. 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and Alamar blue cell viability assays were used to study the biocompatibility. Finally, the corrosion behaviour of HAp-coatings/Ti6Al4V system was researched by means of Electrochemical Impedance Spectroscopy (EIS). The obtained results showed that the prepared powders were nanocrystalline HAp with little deviations from that present in the human bone. All the prepared HAp coatings deposited on Ti6Al4V showed well-behaved biocompatibility, good bioactivity and corrosion protection properties.

  10. The Effect of Coatings on the Wear Behavior of Ti6Al4V Alloy Used in Biomedical Applications

    Science.gov (United States)

    Danışman, Ş.; Odabas, D.; Teber, M.

    2018-01-01

    The properties expected from implant materials are biocompatibility, long service life and wear resistance. The wear resistance of the implant materials varies according to the type of implant, usage area and the movement. The ability of implant material to be more compatible with biological tissues and to increase the useful life depends on the surface properties. Today many different kind of surface modification techniques are applying on medical and dental implant surfaces to improve surface specifications and wear resistance. In this study TiN, TiAlN, TiCN coatings were applied on Ti6Al4V alloy used as implant material by reactive magnetron sputtering method. The wear resistances of uncoated Ti6Al4V alloy and TiN, TiAlN, TiCN coatings were investigated at room temperature under dry conditions. The wear resistance at different load and different sliding rates were compared using an wear tester. The wear losses, wear track widths and friction coefficients of coated and uncoated Ti6Al4V alloys are taken into account for comparison. The results show that a significant improvement in wear resistance of the alloy with the coating is achieved and TiN-coated Ti6Al4V alloy has the highest wear resistance.

  11. Influence of impact speed on water droplet erosion of TiAl compared with Ti6Al4V.

    Science.gov (United States)

    Mahdipoor, M S; Kirols, H S; Kevorkov, D; Jedrzejowski, P; Medraj, M

    2015-09-22

    Water Droplet Erosion (WDE) as a material degradation phenomenon has been a concern in power generation industries for decades. Steam turbine blades and the compressor blades of gas turbines that use water injection usually suffer from WDE. The present work focuses on studying erosion resistance of TiAl as a potential alloy for turbine blades compared to Ti6Al4V, a frequently used blade alloy. Their erosion behaviour is investigated at different droplet impact speeds to determine the relation between erosion performance and impact speed. It is found that the relationship is governed by a power law equation, ER ~ V(n), where the speed exponent is 7-9 for Ti6Al4V and 11-13 for TiAl. There is a contrast between the observed speed exponent in this work and the ones reported in the literature for Ti6Al4V. It is attributed to the different erosion setups and impingement conditions such as different droplet sizes. To verify this, the erosion experiments were performed at two different droplet sizes, 464 and 603 μm. TiAl showed superior erosion resistance in all erosion conditions; however, its erosion performance exhibits higher sensitivity to the impact speed compared to Ti6Al4V. It means that aggressive erosion conditions decrease the WDE resistance superiority of TiAl.

  12. Effects of heat treatment on microstructure and mechanical behaviour of additive manufactured porous Ti6Al4V

    NARCIS (Netherlands)

    Ahmadi, S.M.; Ashok Kumar Jain, R. K.; Zadpoor, A.A.; Ayas, C.; Popovich, V.

    2018-01-01

    Titanium and its alloys such as Ti6Al4V play a major role in the medical industry as bone implants. Nowadays, by the aid of additive manufacturing (AM), it is possible to manufacture porous complex structures which mimic human bone. However, AM parts are near net shape and post processing may be

  13. Effect of ageing treatment on the microstructure and hardness of the Ti6Al4V Alloy

    CSIR Research Space (South Africa)

    Masete, S

    2015-07-01

    Full Text Available The effects of ageing temperature, time and cooling medium on the microstructure and hardness of a solution treated Ti6Al4V alloy were investigated. The furnace cooling after ageing for 0.5 hours gave a homogenous structure with higher hardness...

  14. Synthesis and Characterization of Hydroxyapatite-Collagen-Chitosan (HA/Col/Chi) Composite Coated on Ti6Al4V

    Science.gov (United States)

    Charlena; Bikharudin, Ahmad; Wahyudi, Setyanto Tri

    2018-01-01

    HA-collagen-chitosan (HA/col/chi) composite is developed to increase bioactivity adhesiveness between the metal and the material composite and to improve corrosion resistance. The Ti6Al4V alloy was coated by soaking in HA/col/chi composite at room temperature and then allowed to stand for 5, 6, and 7 days. Diffraction pattern analysis of the coated Ti6Al4V alloy showed that the dominant phase were HA and Ti6Al4V alloy. Corrosion resistance test in media by using 0.9% NaCl showed the corrosion rate at the level of 0.3567 mpy, which was better than that of the uncoated Ti6Al4V alloy (0.4152 mpy). In vitro cytocompatibility assay on endothelial cell of calf pulmonary artery endothelium (CPAE) (ATCC-CCL 209) showed there was no toxicity in the cell culture with the percent inhibition of 33.33% after 72 hours of incubation.

  15. Statistically Guided Development of Laser-Assisted Cold Spray for Microstructural Control of Ti-6Al-4V

    Science.gov (United States)

    Birt, Aaron M.; Champagne, Victor K.; Sisson, Richard D.; Apelian, Diran

    2017-04-01

    Laser-assisted cold spray (LACS) was used to deposit Ti-6Al-4V powders onto Ti-6Al-4V substrates using nitrogen as a carrier gas. An L25 orthogonal array was created with three parameters independent of particle velocity considered thus to be the independent thermal parameters (ITPs) of LACS: powder feed rate, raster speed, and laser power. A signal-to-noise analysis of the influence of the ITPs on porosity, microhardness, and expected thickness was performed revealing that optimum parameter selection is highly dependent on the targeted property, with the ITPs having the largest influence on porosity. Additional bulk trials (>2.5 mm thick) were deposited using parameters of interest from the orthogonal study. These scaled trials demonstrate that it is possible to produce deposits of Ti-6Al-4V via LACS using nitrogen as a carrier gas with porosity less than 1 pct, which is comparable with values described in literature for more expensive helium-based cold spray of Ti-6Al-4V. Additionally, variation of the ITPs indicates that secondary phases and morphologies can be produced and controlled through the thermomechanical treatment caused in situ to LACS.

  16. Surface chemistry of Ti6Al4V components fabricated using selective laser melting for biomedical applications.

    Science.gov (United States)

    Vaithilingam, Jayasheelan; Prina, Elisabetta; Goodridge, Ruth D; Hague, Richard J M; Edmondson, Steve; Rose, Felicity R A J; Christie, Steven D R

    2016-10-01

    Selective laser melting (SLM) has previously been shown to be a viable method for fabricating biomedical implants; however, the surface chemistry of SLM fabricated parts is poorly understood. In this study, X-ray photoelectron spectroscopy (XPS) was used to determine the surface chemistries of (a) SLM as-fabricated (SLM-AF) Ti6Al4V and (b) SLM fabricated and mechanically polished (SLM-MP) Ti6Al4V samples and compared with (c) traditionally manufactured (forged) and mechanically polished Ti6Al4V samples. The SLM-AF surface was observed to be porous with an average surface roughness (Ra) of 17.6±3.7μm. The surface chemistry of the SLM-AF was significantly different to the FGD-MP surface with respect to elemental distribution and their existence on the outermost surface. Sintered particles on the SLM-AF surface were observed to affect depth profiling of the sample due to a shadowing effect during argon ion sputtering. Surface heterogeneity was observed for all three surfaces; however, vanadium was witnessed only on the mechanically polished (SLM-MP and FGD-MP) surfaces. The direct and indirect 3T3 cell cytotoxicity studies revealed that the cells were viable on the SLM fabricated Ti6Al4V parts. The varied surface chemistry of the SLM-AF and SLM-MP did not influence the cell behaviour. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  17. Selective Laser Melting Produced Ti-6Al-4V: Post-Process Heat Treatments to Achieve Superior Tensile Properties.

    Science.gov (United States)

    Ter Haar, Gerrit M; Becker, Thorsten H

    2018-01-17

    Current post-process heat treatments applied to selective laser melting produced Ti-6Al-4V do not achieve the same microstructure and therefore superior tensile behaviour of thermomechanical processed wrought Ti-6Al-4V. Due to the growing demand for selective laser melting produced parts in industry, research and development towards improved mechanical properties is ongoing. This study is aimed at developing post-process annealing strategies to improve tensile behaviour of selective laser melting produced Ti-6Al-4V parts. Optical and electron microscopy was used to study α grain morphology as a function of annealing temperature, hold time and cooling rate. Quasi-static uniaxial tensile tests were used to measure tensile behaviour of different annealed parts. It was found that elongated α'/α grains can be fragmented into equiaxial grains through applying a high temperature annealing strategy. It is shown that bi-modal microstructures achieve a superior tensile ductility to current heat treated selective laser melting produced Ti-6Al-4V samples.

  18. Variability in Room Temperature Fatigue Life of Alpha+Beta Processed Ti-6Al-4V (Preprint)

    National Research Council Canada - National Science Library

    Golden, Patrick J; John, Reji; Porter, John

    2008-01-01

    .... This paper will discuss the Ti-6Al-4V life distributions and sources of variability. Crack propagation using small crack growth data is used to predict the low life failures. Methods of modeling and predicting the life distributions will be discussed and demonstrated.

  19. Biocompatibility and Corrosion Protection Behaviour of Hydroxyapatite Sol-Gel-Derived Coatings on Ti6Al4V Alloy

    Directory of Open Access Journals (Sweden)

    Amir A. El Hadad

    2017-01-01

    Full Text Available The aim of this work was to prepare hydroxyapatite coatings (HAp by a sol-gel method on Ti6Al4V alloy and to study the bioactivity, biocompatibility and corrosion protection behaviour of these coatings in presence of simulated body fluids (SBFs. Thermogravimetric/Differential Thermal Analyses (TG/DTA and X-ray Diffraction (XRD have been applied to obtain information about the phase transformations, mass loss, identification of the phases developed, crystallite size and degree of crystallinity of the obtained HAp powders. Fourier Transformer Infrared Spectroscopy (FTIR has been utilized for studying the functional groups of the prepared structures. The surface morphology of the resulting HAp coatings was studied by Scanning Electron Microscopy (SEM. The bioactivity was evaluated by soaking the HAp-coatings/Ti6Al4V system in Kokubo’s Simulated Body Fluid (SBF applying Inductively Coupled Plasma (ICP spectrometry. 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT and Alamar blue cell viability assays were used to study the biocompatibility. Finally, the corrosion behaviour of HAp-coatings/Ti6Al4V system was researched by means of Electrochemical Impedance Spectroscopy (EIS. The obtained results showed that the prepared powders were nanocrystalline HAp with little deviations from that present in the human bone. All the prepared HAp coatings deposited on Ti6Al4V showed well-behaved biocompatibility, good bioactivity and corrosion protection properties.

  20. Microstructure and Properties of the Ti6Al4V/Inconel 625 Bimetal Obtained by Explosive Joining

    Science.gov (United States)

    Topolski, Krzysztof; Szulc, Zygmunt; Garbacz, Halina

    2016-08-01

    The study is concerned with the bimetallic plate composed of the Ti6Al4V and Inconel 625 alloys. The alloys were joined together using the explosive method with the aim to produce a bimetallic joint. The structure and the mechanical properties of the as-received raw Ti6Al4V and Inconel 625 alloys, the Ti6Al4V/Inconel 625 joint, and the joint after annealing (600 °C for 1 h) were examined. The samples observations were performed using a light microscope and a scanning electron microscope. The mechanical properties were estimated by microhardness measurements, tensile tests, and three-point bending tests. Moreover, the deformation strengthening of the metals and the strength of the joint were analyzed. The explosive process resulted in a good quality bimetallic joint. Both sheets were deformed plastically and the joint surface between the alloys had a wavy shape. In the area of the joint surface, the hardness was increased. For example, the annealing at 600 °C for 1 h resulted in changes of the microhardness in the entire volume of the samples and in changes of the morphology of the joint surface. In three-point bending tests, the samples were examined in two opposite positions (Ti6Al4V on the top or Inconel 625 on the top). The results indicated to depend on the position in which the sample was tested.

  1. X-ray measurement of residual stresses in laser surface melted Ti-6Al-4V alloy

    NARCIS (Netherlands)

    Robinson, J.M.; van Brussel, B.A.; de Hosson, J.T.M.; Reed, R.C.

    1996-01-01

    In this paper, we report on the residual stresses in laser surface melted Ti-6Al-4V, determined using X-ray diffraction methods. The principal result is that there is an increase in the transverse residual stress with each successive, overlapping laser track. The result can be used to explain the

  2. Microstructure and mechanical properties of plasma sprayed HA/YSZ/Ti-6Al-4V composite coatings.

    Science.gov (United States)

    Khor, K A; Gu, Y W; Pan, D; Cheang, P

    2004-08-01

    Plasma sprayed hydroxyapatite (HA) coatings on titanium alloy substrate have been used extensively due to their excellent biocompatibility and osteoconductivity. However, the erratic bond strength between HA and Ti alloy has raised concern over the long-term reliability of the implant. In this paper, HA/yttria stabilized zirconia (YSZ)/Ti-6Al-4V composite coatings that possess superior mechanical properties to conventional plasma sprayed HA coatings were developed. Ti-6Al-4V powders coated with fine YSZ and HA particles were prepared through a unique ceramic slurry mixing method. The so-formed composite powder was employed as feedstock for plasma spraying of the HA/YSZ/Ti-6Al-4V coatings. The influence of net plasma energy, plasma spray standoff distance, and post-spray heat treatment on microstructure, phase composition and mechanical properties were investigated. Results showed that coatings prepared with the optimum plasma sprayed condition showed a well-defined splat structure. HA/YSZ/Ti-6Al-4V solid solution was formed during plasma spraying which was beneficial for the improvement of mechanical properties. There was no evidence of Ti oxidation from the successful processing of YSZ and HA coated Ti-6Al-4V composite powders. Small amount of CaO apart from HA, ZrO(2) and Ti was present in the composite coatings. The microhardness, Young's modulus, fracture toughness, and bond strength increased significantly with the addition of YSZ. Post-spray heat treatment at 600 degrees C and 700 degrees C for up to 12h was found to further improve the mechanical properties of coatings. After the post-spray heat treatment, 17.6% increment in Young's modulus (E) and 16.3% increment in Vicker's hardness were achieved. The strengthening mechanisms of HA/YSZ/Ti-6Al-4V composite coatings were related to the dispersion strengthening by homogeneous distribution of YSZ particles in the matrix, the good mechanical properties of Ti-6Al-4V and the formation of solid solution among HA

  3. Ti-6Al-4V triply periodic minimal surface structures for bone implants fabricated via selective laser melting.

    Science.gov (United States)

    Yan, Chunze; Hao, Liang; Hussein, Ahmed; Young, Philippe

    2015-11-01

    Triply periodic minimal surface (TPMS) structures have already been shown to be a versatile source of biomorphic scaffold designs. Therefore, in this work, Ti-6Al-4V Gyroid and Diamond TPMS lattices having an interconnected high porosity of 80-95% and pore sizes in the range of 560-1600 μm and 480-1450 μm respectively were manufactured by selective laser melting (SLM) for bone implants. The manufacturability, microstructure and mechanical properties of the Ti-6Al-4V TPMS lattices were evaluated. Comparison between 3D micro-CT reconstructed models and original CAD models of the Ti-6Al-4V TPMS lattices shows excellent reproduction of the designs. The as-built Ti-6Al-4V struts exhibit the microstructure of columnar grains filled with very fine and orthogonally oriented α' martensitic laths with the width of 100-300 nm and have the microhardness of 4.01 ± 0.34 GPa. After heat treatment at 680°C for 4h, the α' martensite was converted to a mixture of α and β, in which the α phase being the dominant fraction is present as fine laths with the width of 500-800 nm and separated by a small amount of narrow, interphase regions of dark β phase. Also, the microhardness is decreased to 3.71 ± 0.35 GPa due to the coarsening of the microstructure. The 80-95% porosity TPMS lattices exhibit a comparable porosity with trabecular bone, and the modulus is in the range of 0.12-1.25 GPa and thus can be adjusted to the modulus of trabecular bone. At the same range of porosity of 5-10%, the moduli of cortical bone and of the Ti-6Al-4V TPMS lattices are in a similar range. Therefore, the modulus and porosity of Ti-6Al-4V TPMS lattices can be tailored to the levels of human bones and thus reduce or avoid "stress shielding" and increase longevity of implants. Due to the biomorphic designs, and high interconnected porosity and stiffness comparable to human bones, SLM-made Ti-6Al-4V TPMS lattices can be a promising material for load bearing bone implants. Copyright © 2015 Elsevier

  4. A Study of Electrochemical Machining of Ti-6Al-4V in NaNO3 solution.

    Science.gov (United States)

    Li, Hansong; Gao, Chuanping; Wang, Guoqian; Qu, Ningsong; Zhu, Di

    2016-10-13

    The titanium alloy Ti-6Al-4V is used in many industries including aviation, automobile manufacturing, and medical equipment, because of its low density, extraordinary corrosion resistance and high specific strength. Electrochemical machining (ECM) is a non-traditional machining method that allows applications to all kinds of metallic materials in regardless of their mechanical properties. It is widely applied to the machining of Ti-6Al-4V components, which usually takes place in a multicomponent electrolyte solution. In this study, a 10% NaNO 3 solution was used to make multiple holes in Ti-6Al-4V sheets by through-mask electrochemical machining (TMECM). The polarization curve and current efficiency curve of this alloy were measured to understand the electrical properties of Ti-6Al-4V in a 10% NaNO 3 solution. The measurements show that in a 10% NaNO 3 solution, when the current density was above 6.56 A·cm -2 , the current efficiency exceeded 100%. According to polarization curve and current efficiency curve, an orthogonal TMECM experiment was conducted on Ti-6Al-4V. The experimental results suggest that with appropriate process parameters, high-quality holes can be obtained in a 10% NaNO 3 solution. Using the optimized process parameters, an array of micro-holes with an aperture of 2.52 mm to 2.57 mm and maximum roundness of 9 μm were produced using TMECM.

  5. Functionalization of Biomedical Ti6Al4V via In Situ Alloying by Cu during Laser Powder Bed Fusion Manufacturing.

    Science.gov (United States)

    Krakhmalev, Pavel; Yadroitsev, Igor; Yadroitsava, Ina; de Smidt, Olga

    2017-10-03

    The modern medical industry successfully utilizes Laser Powder Bed Fusion (LPBF) to manufacture complex custom implants. Ti6Al4V is one of the most commonly used biocompatible alloys. In surgery practice, infection at the bone-implant interface is one of the key reasons for implant failure. Therefore, advanced implants with biocompatibility and antibacterial properties are required. Modification of Ti alloy with Cu, which in small concentrations is a proven non-toxic antibacterial agent, is an attractive way to manufacture implants with embedded antibacterial functionality. The possibility of achieving alloying in situ, during manufacturing, is a unique option of the LPBF technology. It provides unique opportunities to manufacture customized implant shapes and design new alloys. Nevertheless, optimal process parameters need to be established for the in situ alloyed materials to form dense parts with required mechanical properties. This research is dedicated to an investigation of Ti6Al4V (ELI)-1 at % Cu material, manufactured by LPBF from a mixture of Ti6Al4V (ELI) and pure Cu powders. The effect of process parameters on surface roughness, chemical composition and distribution of Cu was investigated. Chemical homogeneity was discussed in relation to differences in the viscosity and density of molten Cu and Ti6Al4V. Microstructure, mechanical properties, and fracture behavior of as-built 3D samples were analyzed and discussed. Pilot antibacterial functionalization testing of Ti6Al4V (ELI) in situ alloyed with 1 at % Cu showed promising results and notable reduction in the growth of pure cultures of Escherichia coli and Staphylococcus aureus.

  6. Functionalization of Biomedical Ti6Al4V via In Situ Alloying by Cu during Laser Powder Bed Fusion Manufacturing

    Directory of Open Access Journals (Sweden)

    Pavel Krakhmalev

    2017-10-01

    Full Text Available The modern medical industry successfully utilizes Laser Powder Bed Fusion (LPBF to manufacture complex custom implants. Ti6Al4V is one of the most commonly used biocompatible alloys. In surgery practice, infection at the bone–implant interface is one of the key reasons for implant failure. Therefore, advanced implants with biocompatibility and antibacterial properties are required. Modification of Ti alloy with Cu, which in small concentrations is a proven non-toxic antibacterial agent, is an attractive way to manufacture implants with embedded antibacterial functionality. The possibility of achieving alloying in situ, during manufacturing, is a unique option of the LPBF technology. It provides unique opportunities to manufacture customized implant shapes and design new alloys. Nevertheless, optimal process parameters need to be established for the in situ alloyed materials to form dense parts with required mechanical properties. This research is dedicated to an investigation of Ti6Al4V (ELI-1 at % Cu material, manufactured by LPBF from a mixture of Ti6Al4V (ELI and pure Cu powders. The effect of process parameters on surface roughness, chemical composition and distribution of Cu was investigated. Chemical homogeneity was discussed in relation to differences in the viscosity and density of molten Cu and Ti6Al4V. Microstructure, mechanical properties, and fracture behavior of as-built 3D samples were analyzed and discussed. Pilot antibacterial functionalization testing of Ti6Al4V (ELI in situ alloyed with 1 at % Cu showed promising results and notable reduction in the growth of pure cultures of Escherichia coli and Staphylococcus aureus.

  7. Electrophoretic deposition of bioactive silica-calcium phosphate nanocomposite on Ti-6Al-4V orthopedic implant.

    Science.gov (United States)

    Aniket; El-Ghannam, Ahmed

    2011-11-01

    Bioactive silica-calcium phosphate nanocomposite (SCPC) has been coated on Ti-6Al-4V implant employing an electrophoretic deposition (EPD) technique. The effects of composition and pH of the suspending medium on the zeta potential of three different SCPC formulations; SCPC25, SCPC50 and SCPC75 were analyzed. The average zeta potential of SCPC50 in pure ethanol was more negative than that of SCPC25 or SCPC75; however, the difference was not statistically significant. Discs of Ti-6Al-4V were passivated, coated with SCPC50 (200 nm-10 μm) and thermally treated at 600-800°C to produce a coating thickness in the range of 43.1 ± 5.7 to 30.1 ± 4.6 μm. After treatment at 600, 700, and 800°C, the adhesion strength at the SCPC50/Ti-6Al-4V interface was 42.6 ± 3.6, 44.7 ± 8.7, and 47.2 ± 4.3 MPa, respectively. SEM-EDX analyses of SCPC50-coated Ti-6Al-4V preimmersed in PBS for 7 days showed the formation of a Ca-deficient hydroxyapatite surface layer. ICP-OES analyses of the immersing solution (n = 6) showed an increase in the ionic concentration of Si from 3.3 ± 0.9 to 5.0 ± 1.2 ppm between days 1 and 4; after which no significant change in the Si concentration was measured. Bone marrow mesenchymal stem cells attached to the SCPC50-coated implants expressed significantly higher (p SCPC50 can efficiently be coated on Ti-6Al-4V using EPD. The SCPC50 coating has the potential to enhance bone integration with the orthopedic implant. 2011 Wiley Periodicals, Inc.

  8. Mechanical and chemical analyses across dental porcelain fused to CP titanium or Ti6Al4V

    International Nuclear Information System (INIS)

    Souza, Júlio C.M.; Henriques, Bruno; Ariza, Edith; Martinelli, Antonio E.; Nascimento, Rubens M.; Silva, Filipe S.; Rocha, Luís A.; Celis, Jean-Pierre

    2014-01-01

    The aim of this study was to evaluate the evolution of mechanical properties and chemical variation across veneering dental porcelain fused to different titanium-based substrates. Test samples were synthesized by fusing dental feldspar-based porcelain onto commercially pure titanium grade II or Ti6Al4V alloy. Samples were cross-sectioned at angles of 10 and 90° to the interface plane. Afterwards, nanoindentation tests and Scanning Electron Microscopy (SEM) imaging coupled to an Energy Dispersive Spectroscopy (EDS) system were carried out across interfaces extending from the metal towards the porcelain area. Elemental diffusion profiles across the porcelain-to-metal interfaces were also obtained by EDS analysis. The mismatch in mechanical properties found in porcelain-to-Ti6Al4V interfaces was lower than that of porcelain-to-CP titanium. Cracking was noticed at low-thickness veneering dental porcelain regions after the nanoindentation tests of samples cross-sectioned at low angles to the interface plane. A wide reaction zone between titanium and porcelain as well as higher incidence of defects was noticed at the porcelain-to-CP titanium interfaces. This study confirmed Ti6Al4V as an improved alternative to CP-titanium as it showed to establish a better interface with the veneering dental porcelain considering the slight chemical interaction and the lower mechanical properties mismatch. The elastic modulus of porcelain-to-Ti6Al4V samples showed to be less sensitive to porcelain thickness variations. - Highlights: • This study reveals mechanical and chemical behaviors across porcelain/titanium interfaces. • Cracks were noticed after nanoindentation on thin porcelain layers. • Ti6Al4V/porcelain showed a better mechanical behavior than that at CP-Ti/porcelain

  9. Mechanical and chemical analyses across dental porcelain fused to CP titanium or Ti6Al4V

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Júlio C.M., E-mail: jsouza@dem.uminho.pt [Centre of Microelectromechanical Systems (CMEMS), Dept. of Mechanical Engineering, Universidade do Minho, P-4800-058 Guimarães (Portugal); PPGO, CCS, Dept. of Dentistry (ODT), Universidade Federal de Santa Catarina (UFSC), 88040-900 Florianópolis, SC (Brazil); Henriques, Bruno [Centre of Microelectromechanical Systems (CMEMS), Dept. of Mechanical Engineering, Universidade do Minho, P-4800-058 Guimarães (Portugal); Dept. Materials Engineering, Universidade Federal do Rio Grande do Norte (UFRN), 59072-970 Natal, RN (Brazil); Ariza, Edith [Centre of Microelectromechanical Systems (CMEMS), Dept. of Mechanical Engineering, Universidade do Minho, P-4800-058 Guimarães (Portugal); Martinelli, Antonio E.; Nascimento, Rubens M. [Dept. Materials Engineering, Universidade Federal do Rio Grande do Norte (UFRN), 59072-970 Natal, RN (Brazil); Silva, Filipe S. [Centre of Microelectromechanical Systems (CMEMS), Dept. of Mechanical Engineering, Universidade do Minho, P-4800-058 Guimarães (Portugal); Rocha, Luís A. [Centre of Microelectromechanical Systems (CMEMS), Dept. of Mechanical Engineering, Universidade do Minho, P-4800-058 Guimarães (Portugal); Dept. of Physics, Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP), 17033-360, Bauru SP (Brazil); Celis, Jean-Pierre [Dept. MTM, Katholieke Universiteit Leuven, B-3001 Leuven (Belgium)

    2014-04-01

    The aim of this study was to evaluate the evolution of mechanical properties and chemical variation across veneering dental porcelain fused to different titanium-based substrates. Test samples were synthesized by fusing dental feldspar-based porcelain onto commercially pure titanium grade II or Ti6Al4V alloy. Samples were cross-sectioned at angles of 10 and 90° to the interface plane. Afterwards, nanoindentation tests and Scanning Electron Microscopy (SEM) imaging coupled to an Energy Dispersive Spectroscopy (EDS) system were carried out across interfaces extending from the metal towards the porcelain area. Elemental diffusion profiles across the porcelain-to-metal interfaces were also obtained by EDS analysis. The mismatch in mechanical properties found in porcelain-to-Ti6Al4V interfaces was lower than that of porcelain-to-CP titanium. Cracking was noticed at low-thickness veneering dental porcelain regions after the nanoindentation tests of samples cross-sectioned at low angles to the interface plane. A wide reaction zone between titanium and porcelain as well as higher incidence of defects was noticed at the porcelain-to-CP titanium interfaces. This study confirmed Ti6Al4V as an improved alternative to CP-titanium as it showed to establish a better interface with the veneering dental porcelain considering the slight chemical interaction and the lower mechanical properties mismatch. The elastic modulus of porcelain-to-Ti6Al4V samples showed to be less sensitive to porcelain thickness variations. - Highlights: • This study reveals mechanical and chemical behaviors across porcelain/titanium interfaces. • Cracks were noticed after nanoindentation on thin porcelain layers. • Ti6Al4V/porcelain showed a better mechanical behavior than that at CP-Ti/porcelain.

  10. Life expectancy of modular Ti6Al4V hip implants: influence of stress and environment.

    Science.gov (United States)

    Chandra, A; Ryu, J J; Karra, P; Shrotriya, P; Tvergaard, V; Gaisser, M; Weik, T

    2011-11-01

    Stress dependent electrochemical dissolution is identified as one of the key mechanisms governing surface degradation in fretting and crevice corrosion of biomedical implants. The present study focuses on delineating the roles of mechanical stress and chemical conditions on the life expectancy of modular hip implants. First, material removal on a stressed surface of Ti6Al4V subjected to single asperity contact is investigated experimentally to identify the influence of contact load, in-plane stress and chemical environment on mean wear rates. A range of known stress levels are applied to the specimen while its surface is mechanically stimulated in different non-reactive to oxidizing aqueous environments. Evolution of surface degradation is monitored, and its mechanism is elucidated. This phase allows estimation of Preston Constant which is later used in the analysis. Second phase of the work is semi-analytical and computational, where, based on the estimated Preston constant and other material and process parameters, the scratch propensity (consisting of magnitude of scratch depth and their frequency per unit area) due to micro-motion in modular hip implants is estimated. The third phase views these scratches as initial notches and utilizes a mixed-mode fatigue crack propagation model to estimate the critical crack length for onset of instability. The number of loading cycles needed to reach this critical crack length is then labeled as the expected life of the implant under given mechanical and chemical conditions. Implications of different material and process conditions to life expectancy of orthopedic implants are discussed. It is observed that transverse micro-motion, compared to longitudinal micro-motion, plays a far more critical role in determining the implant life. Patient body weight, as well as proximity of the joint fluid to its iso-electric point play key roles in determining wear rates and associated life expectancies of modular hip implants

  11. Pre-fatigue influence on quasi-static tensile properties of Ti-6Al-4V in thin-sheet form

    Directory of Open Access Journals (Sweden)

    De Baere I.

    2010-06-01

    Full Text Available The response of engineering structures to loads is most often assessed without taking possible damage of the used material(s into account. However, it has already been proved that a preceding cyclic loading and the alteration of the microstructure it causes, can have a significant influence on the mechanical properties of steel grades and aluminium alloys , and hence on the behaviour of structural elements made of it. Ti-6Al4V, the most widely used titanium alloy, is often one of the materials chosen for cyclic loading applications where other solicitations are present too. Therefore, the influence of pre-fatigue on the quasi-static mechanical properties of Ti-6Al-4V in thin-sheet form is investigated. Tensile experiments are performed on samples subjected to different damage levels. The material does not show a clear dependence of its tensile properties with previous loading cycles, although the overall effect can be important for particular geometries.

  12. Surface Modification of the Ti6Al4V Alloy with Silicon Carbonitride Layer Deposited by PACVD Method

    Science.gov (United States)

    Jonas, Stanisława; Konefał-Góral, Jadwiga; Małek, Anna; Kluska, Stanisława; Grzesik, Zbigniew

    2014-09-01

    Four different layers of various silicon, carbon and nitrogen contents on the Ti6Al4V alloy and (001)Si wafers have been deposited by means of Plasma Assisted Chemical Vapor Deposition (PACVD) method. The layers were obtained from reactive gas mixture containing SiH4, CH4, NH3 and Ar. After deposition the structure and chemical composition of modified surfaces have been analyzed with use of SEM/EDS technique. Based on these results and thermodynamic calculations, the diffusion coefficients, D, for nitrogen and carbon in alloy were discussed. Scratch test shown that silicon carbonitride layers have good adhesion to metal surface. In order to determine atomic structure of obtained layers, FTIR spectra for layer-(001)Si and layer-Ti6Al4V were registered.

  13. In vitro electrochemical behaviour of Chitosan-PEG coatings obtained on Ti6Al4V by dip coating

    Science.gov (United States)

    Sandoval Amador, A.; Guerrero-Barajas, S. M.; Hernandez-Salas, D. R.; Sierra-Herrera, D. K.; Estupiñan-Duran, H. A.; Y Peña Ballesteros, D.

    2017-12-01

    In the present study, coatings of Chitosan - Polyethylene Glycol was obtained by dip coating on Ti6Al4V from polymer mixtures (30-70, 50-50, 70-30). The aim of our study was analysed their ability to formation of apatite and their electrochemical behaviour in the presence of a simulated physiological fluid. The coating properties were evaluated by electrochemical impedance, atomic absorption, SEM and FTIR techniques. The results showed that surfaces coated with a 50-50 ratio of chitosan PEG stimulate the formation of calcium phosphates on the surface of the material. On the other hand, it was found that the number of layers generate a very significant effect on the resistance to the degradation of the alloy in the presence of SBF, generating an increase of up to 1 and 3 orders of magnitude in the impedance of the coating of 5 and 7 layers respectively compared to the Ti6Al4V alloy.

  14. Sustainability Assessment for Dry, Conventional and Cryogenic Machining in Face Milling of Ti-6Al-4V

    Directory of Open Access Journals (Sweden)

    IMRAN MASOOD

    2017-04-01

    Full Text Available Sustainability achievement in difficult-to-machine materials is major concern now-a-days. This paper presents sustainability assessment of machining titanium alloy Ti-6Al-4V. Face milling of Ti-6Al-4V hardened to 55 HRC with PVD (Physical Vapour Deposition coated inserts was analyzed for dry, conventional and cryogenic cooling modes. Experiments were designed using CCD (Central Composite Design for modeling and analysis of surface roughness. Feed, speed and depth of cut were used as input parameters. For a specific surface finish, the three cooling modes were compared for cutting power, machining time and material removal rate. The results indicate that cryogenic cooling was more sustainable as compared to dry and conventional cooling process. This sustainable model will help to select sustainable input parameters.

  15. In situ observation of texture and microstructure evolution during rolling and globularization of Ti-6Al-4V

    KAUST Repository

    Warwick, Jonnathan L W

    2013-03-01

    The evolution of texture in β-annealed Ti-6Al-4V during α-β rolling and so-called recrystallization annealing has been examined using synchrotron X-ray diffraction and ex situ characterization. During rolling, the initial α (0 0 0 2) texture softens and the colony α becomes kinked. During globularization, the texture strengthens as highly strained (and hence misoriented) areas of the laths disappear and this strengthening continues once coarsening of the primary α becomes dominant. At shorter heat treatment times the αs laths that form on cooling do so with a range of variant-related orientations to the β, but at longer annealing times this αs takes on the orientation of the surrounding αp. The implications for the mechanical performance of macrozone-containing bimodal Ti-6Al-4V material are discussed. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  16. Experimental Study of Direct Laser Deposition of Ti-6Al-4V and Inconel 718 by Using Pulsed Parameters

    Directory of Open Access Journals (Sweden)

    Kamran Shah

    2014-01-01

    Full Text Available Laser direct metal deposition (LDMD has developed from a prototyping to a single metal manufacturing tool. Its potential for creating multimaterial and functionally graded structures is now beginning to be explored. This work is a first part of a study in which a single layer of Inconel 718 is deposited on Ti-6Al-4V substrate. Single layer tracks were built at a range of powder mass flow rates using a coaxial nozzle and 1.5 kW diode laser operating in both continuous and pulsed beam modes. This part of the study focused on the experimental findings during the deposition of Inconel 718 powder on Ti-6Al-4V substrate. Scanning electron microscopy (SEM and X-ray diffraction analysis were performed for characterization and phase identification. Residual stress measurement had been carried out to ascertain the effects of laser pulse parameters on the crack development during the deposition process.

  17. Sustainability assessment for dry, conventional and cryogenic machining in face milling of ti-6al-4v

    International Nuclear Information System (INIS)

    Masood, I.; Jahanzaib, M.; Wasim, A.

    2017-01-01

    Sustainability achievement in difficult-to-machine materials is major concern now-a-days. This paper presents sustainability assessment of machining titanium alloy Ti-6Al-4V. Face milling of Ti-6Al-4V hardened to 55 HRC with PVD (Physical Vapour Deposition) coated inserts was analyzed for dry, conventional and cryogenic cooling modes. Experiments were designed using CCD (Central Composite Design) for modeling and analysis of surface roughness. Feed, speed and depth of cut were used as input parameters. For a specific surface finish, the three cooling modes were compared for cutting power, machining time and material removal rate. The results indicate that cryogenic cooling was more sustainable as compared to dry and conventional cooling process. This sustainable model will help to select sustainable input parameters. (author)

  18. Microstructure and tensile properties of Ti-6Al-4V alloys manufactured by selective laser melting with optimized processing parameters

    Science.gov (United States)

    Wang, L.; Ma, C.; Huang, J.; Ding, H. Y.; Chu, M. Q.

    2017-11-01

    Selective laser melting (SLM) is a precise additive manufacturing process that the metallic powders without binder are melted layer by layer to complex components using a high bright fiber laser. In the paper, Ti-6Al-4V alloy was fabricated by SLM and its microstructure and mechanical properties were investigated in order to evaluate the SLM process. The results show that the microstructure exists anisotropy between the horizontal and vertical section due to the occurrence of epitaxial growth, and the former microstructure seems equal-axis and the latter is column. Moreover, there is little difference in tensile test between the horizontal and vertical sections. Furthermore, the tensile properties of fabricated Ti-6Al-4V alloy by SLM are higher than the forged standard ones. However, the fatigue results show that there are some scatters, which need further investigation to define the fatigue initiation.

  19. Characterization of Ti-6%Al-4%V and VascoMax C-350

    International Nuclear Information System (INIS)

    Sunwoo, A J

    2005-01-01

    The α-β Ti-6% Al-4% V (Ti64) alloy can be heat treated to meet the specified requirements of the applications. The as-received material from SLAC was given a solution heat treatment (SHT) to have a good strength and ductility combination. The SHT was done at 200 C below the Beta transus of 990 C for 15 min and air-cooled to 20 C. The designed microstructure consists of β phase precipitates within the α phase matrix. The characterization of the as-received Ti64 alloy sheet microstructure reveals equiaxed, 10 (micro)m-sized grains on the flat surface and finer, 8 (micro)m-sized grains in the through thickness. Figures 1 and 2 show the microstructure of the alloy. The typical Ti64 microstructure is lamellar structure, consisting of alternating α and β phases. In order for the alloy to have the micron sized, equiaxed grains, it had to undergo extensive wrought processing. The Vicker's microhardness numbers (VHN) showed that the slightly larger grained flat surface had a higher averaged value than the through thickness; 33 kg/mm 2 vs. 30 kg/mm 2 . The residual effect of wrought processing is still present even after the SHT to cause the small difference in the hardness values. The results of tensile tests conducted at LLNL and at BNL are given in Tables 2 and 1 in Appendices 1 and 2, respectively. The effects of the irradiation dosage damage on the tensile properties of the Ti64 are presented in Appendix 2. The as-received tensile specimens are not the standard specimens for testing. As shown in Attachment, Figure 1, only the 6 mm length is used in the reduced gage section of the specimens. As a result, a small change in the gage length will translate to a higher percentage change in elongation, giving higher elongation values than using the 30 mm length of the specimen. Since most of the deformation is concentrated in the reduced gage section, the present results are more accurate measurement of ductility. The Ti64 specimens failed in the center of the gage

  20. In vitro and in vivo performance of bioactive Ti6Al4V/TiC/HA implants fabricated by a rapid microwave sintering technique

    Energy Technology Data Exchange (ETDEWEB)

    Choy, Man Tik; Tang, Chak Yin, E-mail: mfcytang@polyu.edu.hk; Chen, Ling; Wong, Chi Tak; Tsui, Chi Pong

    2014-09-01

    Failure of the bone–implant interface in a joint prosthesis is a main cause of implant loosening. The introduction of a bioactive substance, hydroxyapatite (HA), to a metallic bone–implant may enhance its fixation on human bone by encouraging direct bone bonding. Ti6Al4V/TiC/HA composites with a reproducible porous structure (porosity of 27% and pore size of 6–89 μm) were successfully fabricated by a rapid microwave sintering technique. This method allows the biocomposites to be fabricated in a short period of time under ambient conditions. Ti6Al4V/TiC/HA composites exhibited a compressive strength of 93 MPa, compressive modulus of 2.9 GPa and microhardness of 556 HV which are close to those of the human cortical bone. The in vitro preosteoblast MC3T3-E1 cells cultured on the Ti6Al4V/TiC/HA composite showed that the composite surface could provide a biocompatible environment for cell adhesion, proliferation and differentiation without any cytotoxic effects. This is among the first attempts to study the in vivo performance of load-bearing Ti6Al4V/TiC and Ti6Al4V/TiC/HA composites in a live rabbit. The results indicated that the Ti6Al4V/TiC/HA composite had a better bone–implant interface compared with the Ti6Al4V/TiC implant. Based on the microstructural features, the mechanical properties, and the in vitro and in vivo test results from this study, the Ti6Al4V/TiC/HA composites have the potential to be employed in load-bearing orthopedic applications. - Highlights: • Ti6Al4V/TiC and Ti6Al4V/TiC/HA composites were fabricated by microwave sintering. • Ti6Al4V/TiC/HA exhibited mechanical properties close to human cortical bone. • Ti6Al4V/TiC/HA could provide a biocompatible environment for bone cell growth. • Ti6Al4V/TiC/HA showed a better bone–implant interface than Ti6Al4V/TiC. • Ti6Al4V/TiC/HA could be used for bone replacement under load-bearing conditions.

  1. In vitro and in vivo performance of bioactive Ti6Al4V/TiC/HA implants fabricated by a rapid microwave sintering technique

    International Nuclear Information System (INIS)

    Choy, Man Tik; Tang, Chak Yin; Chen, Ling; Wong, Chi Tak; Tsui, Chi Pong

    2014-01-01

    Failure of the bone–implant interface in a joint prosthesis is a main cause of implant loosening. The introduction of a bioactive substance, hydroxyapatite (HA), to a metallic bone–implant may enhance its fixation on human bone by encouraging direct bone bonding. Ti6Al4V/TiC/HA composites with a reproducible porous structure (porosity of 27% and pore size of 6–89 μm) were successfully fabricated by a rapid microwave sintering technique. This method allows the biocomposites to be fabricated in a short period of time under ambient conditions. Ti6Al4V/TiC/HA composites exhibited a compressive strength of 93 MPa, compressive modulus of 2.9 GPa and microhardness of 556 HV which are close to those of the human cortical bone. The in vitro preosteoblast MC3T3-E1 cells cultured on the Ti6Al4V/TiC/HA composite showed that the composite surface could provide a biocompatible environment for cell adhesion, proliferation and differentiation without any cytotoxic effects. This is among the first attempts to study the in vivo performance of load-bearing Ti6Al4V/TiC and Ti6Al4V/TiC/HA composites in a live rabbit. The results indicated that the Ti6Al4V/TiC/HA composite had a better bone–implant interface compared with the Ti6Al4V/TiC implant. Based on the microstructural features, the mechanical properties, and the in vitro and in vivo test results from this study, the Ti6Al4V/TiC/HA composites have the potential to be employed in load-bearing orthopedic applications. - Highlights: • Ti6Al4V/TiC and Ti6Al4V/TiC/HA composites were fabricated by microwave sintering. • Ti6Al4V/TiC/HA exhibited mechanical properties close to human cortical bone. • Ti6Al4V/TiC/HA could provide a biocompatible environment for bone cell growth. • Ti6Al4V/TiC/HA showed a better bone–implant interface than Ti6Al4V/TiC. • Ti6Al4V/TiC/HA could be used for bone replacement under load-bearing conditions

  2. Preliminary study on the corrosion resistance, antibacterial activity and cytotoxicity of selective-laser-melted Ti6Al4V-xCu alloys.

    Science.gov (United States)

    Guo, Sai; Lu, Yanjin; Wu, Songquan; Liu, Lingling; He, Mengjiao; Zhao, Chaoqian; Gan, Yiliang; Lin, Junjie; Luo, Jiasi; Xu, Xiongcheng; Lin, Jinxin

    2017-03-01

    In this study, a series of Cu-bearing Ti6Al4V-xCu (x=0, 2, 4, 6wt%) alloys (shorten by Ti6Al4V, 2C, 4C, and 6C, respectively.) with antibacterial function were successfully fabricated by selective laser melting (SLM) technology with mixed spherical powders of Cu and Ti6Al4V for the first time. In order to systematically investigate the effects of Cu content on the microstructure, phase constitution, corrosion resistance, antibacterial properties and cytotoxicity of SLMed Ti6Al4V-xCu alloys, experiments including XRD, SEM-EDS, electrochemical measurements, antibacterial tests and cytotoxicity tests were conducted with comparison to SLMed Ti6Al4V alloy (Ti6Al4V). Microstructural observations revealed that Cu had completely fused into the Ti6Al4V alloy, and presented in the form of Ti 2 Cu phase at ambient temperature. With Cu content increase, the density of the alloy gradually decreased, and micropores were obviously found in the alloy. Electrochemical measurements showed that corrosion resistance of Cu-bearing alloys were stronger than Cu-free alloy. Antibacterial tests demonstrated that 4C and 6C alloys presented strong and stable antibacterial property against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) compared to the Ti6Al4V and 2C alloy. In addition, similar to the Ti6Al4V alloy, the Cu-bearing alloys also exerted good cytocompatibility to the Bone Marrow Stromal Cells (BMSCs) from Sprague Dawley (SD) rats. Based on those results, the preliminary study verified that it was feasible to fabricated antibacterial Ti6Al4V-xCu alloys direct by SLM processing mixed commercial Ti6Al4V and Cu powder. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Effect of pickling solution on the surface morphology of Ti6Al4V alloy investment cast

    CSIR Research Space (South Africa)

    Mutombo, K

    2011-10-01

    Full Text Available Ti6Al4V alloy interacted with yttria fully stabilized zirconia face-coat to generate the alpha-case layer during the investment casting. The alpha-case mainly contained Al2O3, TiO2, TiO0.48, VO2, ZrO2 and Ti2ZrAl as revealed by the Energy dispersive...

  4. Comparison between PEEK and Ti6Al4V concerning micro-scale abrasion wear on dental applications.

    Science.gov (United States)

    Sampaio, M; Buciumeanu, M; Henriques, B; Silva, F S; Souza, J C M; Gomes, J R

    2016-07-01

    In the oral cavity, abrasive wear is predictable at exposed tooth or restorative surfaces, during mastication and tooth brushing. Also, wear can occur at contacting surfaces between the Ti-based prosthetic structures and implants in presence of abrasive compounds from food or toothpaste. Thus, the aim of this work was to compare the abrasive wear resistance of PEEK and Ti6Al4V on three-body abrasion related to different hydrated silica content and loads. Surfaces of Ti6Al4V or PEEK cylinders (8mm diameter and 4mm height) were wet ground on SiC papers and then polished with 1µm diamond paste. After that, surfaces were ultrasonically cleaned in propyl alcohol for 15min and then in distilled water for 10min. Micro-scale abrasion tests were performed at 60rpm and on different normal loads (0.4, 0.8 or 1.2N) after 600 ball revolutions using suspensions with different weight contents of hydrated silica. After abrasive tests, wear scars on flat samples were measured to quantify the wear volume and characterized by scanning electron microscope (SEM) to identify the dominant wear mechanisms. Results showed a higher volume loss rate on PEEK than that recorded on Ti6Al4V,, when subjected to three-body abrasion tests involving hydrated silica suspensions. An increase in volume loss was noted on both tested materials when the abrasive content or load was increased. PEEK was characterized by less wear resistance than that on Ti6Al4V after micro-scale abrasion wear in contact with hydrated silica particles, as commonly found in toothpastes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Study on Ti-6Al-4V Alloy Machining Applying the Non-Resonant Three-Dimensional Elliptical Vibration Cutting

    Directory of Open Access Journals (Sweden)

    Mingming Lu

    2017-10-01

    Full Text Available The poor machinability of Ti-6Al-4V alloy makes it hard to process by conventional processing methods even though it has been widely used in military and civilian enterprise fields. Non-resonant three-dimensional elliptical vibration cutting (3D-EVC is a novel cutting technique which is a significant development potential for difficult-to-cut materials. However, few studies have been conducted on processing the Ti-6Al-4V alloy using the non-resonant 3D-EVC technique, the effect of surface quality, roughness, topography and freeform surface has not been clearly researched yet. Therefore, the machinability of Ti-6Al-4V alloy using the non-resonant 3D-EVC apparatus is studied in this paper. Firstly, the principle of non-resonant 3D-EVC technique and the model of cutter motion are introduced. Then the tool path is synthesized. The comparison experiments are carried out with traditional continuous cutting (TCC, two-dimension elliptical vibration cutting (2D-EVC, and the non-resonant 3D-EVC method. The experimental results shown that the excellent surface and lower roughness (77.3 nm could be obtained using the non-resonant 3D-EVC method; the shape and dimension of elliptical cutting mark also relates to the cutting speed and vibration frequency, and the concave/convex spherical surface topography are achieved by non-resonant 3D-EVC in the Ti-6Al-4V alloy. This proved that the non-resonant 3D-EVC technique has the better machinability compared with the TCC and 2D-EVC methods.

  6. Resistance of direct metal laser sintered Ti6Al4V alloy against growth of fatigue cracks

    Czech Academy of Sciences Publication Activity Database

    Konečná, R.; Kunz, Ludvík; Bača, A.; Nicoletto, G.

    2017-01-01

    Roč. 185, NOV (2017), s. 82-91 ISSN 0013-7944 Institutional support: RVO:68081723 Keywords : Titanium alloys * Ti6Al4V * Fatigue crack growth * Threshold value of stress intensity factor * Direct metal laser sintering Subject RIV: JL - Materials Fatigue, Friction Mechanics OBOR OECD: Audio engineering, reliability analysis Impact factor: 2.151, year: 2016 http://www.sciencedirect.com/science/article/pii/S0013794417300292

  7. Residual Stress Evaluation of a High Performance Machined Pre-formed Ti6Al4V Part

    OpenAIRE

    Dimitrov, D.M.; Laubscher, R.F.; Sterzing, A.; Conradie, P.J.T.; Oosthuizen, G.A.; Blau, P.; Schmidt, G.; Hochmuth, C.; Styger, G.; Zachäus, R.

    2016-01-01

    Near net-shape technologies are increasingly used to enhance resource efficiency in high performance machining for various applications, including aerospace. In this paper the effect of a pre-formed based manufacturing route on the residual stress state of an aerospace part in Ti6Al4V is presented. The manufacturing strategies, including the pre-form and machining stages, are outlined in detail. Two similar preformed billets were manufactured. High performance machining was then conducted at ...

  8. Sustained load crack growth design data for Ti-6Al-4V titanium alloy tanks containing hydrazine

    Science.gov (United States)

    Lewis, J. C.; Kenny, J. T.

    1976-01-01

    Sustained load crack growth data for Ti-6Al-4V titanium alloy in hydrazine per MIL-P-26536 and refined hydrazine are presented. Fracture mechanics data on crack growth thresholds for heat-treated forgings, aged and unaged welds, and aged and unaged heat-affected zones are reported. Fracture mechanics design curves of crack growth threshold stress intensity versus temperature are generated from 40 to 71 C.

  9. Characterization of hydroxyapatite coatings deposited by hydrothermal electrochemical method on NaOH immersed Ti6Al4V

    Energy Technology Data Exchange (ETDEWEB)

    He, Daihua, E-mail: hedh21@163.com [School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai, 200093 (China); Liu, Ping; Liu, Xinkuan; Ma, Fengcang; Chen, Xiaohong; Li, Wei [School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai, 200093 (China); Du, Jiandi; Wang, Pu [School of Mechanical Engineering, University of Shanghai for Science and Technology, Shanghai, 200093 (China); Zhao, Jun [Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai, 200050 (China)

    2016-07-05

    The hydrothermal electrochemical method was used to deposit hydroxyapatite coating on Ti6Al4V. In order to improve the bonding strength between the coating and substrate, the substrates were modified by 8 M NaOH solution before the deposition. The effects of immersing time on the substrate, on the hydroxyapatite coating, and on the bonding strength were studied. X-Ray Diffraction, Scanning Electron Microscope, Fourier Transform Infrared Spectroscopy and Drop Shape Analysis Method were applied. And the crystallinity of hydroxyapatite coating was calculated. The results show that immersing treatment effects the phase compositions, the microstructure and the wettability of the substrate surface. A porous, three-dimensional network structure is formed on the Ti6Al4V surface through the NaOH immersion. The pore size and depth increase with the increase of immersing time from 12 to 48 h. The surface microstructure of Ti6Al4V with 60 h′ immersion time was different from the others. The modification treatment can improve the bonding strength between hydroxyapatite coating and the substrate obviously. The value of the bonding strength with the substrate immersed for 48 h is larger than those of the others. A bone-like apatite layer forms on the coating after 3 days of soaking in SBF, implying with good bioactivity of the hydroxyapatite coatings deposited by the method. The surface characteristics of the sample immersed with 48 h are more conductive to the deposition of hydroxyapatite and to the improvement of the bonding strength. The formation mechanism of hydroxyapatite coating deposited by hydrothermal electrochemical method was discussed. - Highlights: • Immerse Ti6Al4V alloy with NaOH solution for different immersing time. • We deposit hydroxyapatite coating by hydrothermal electrochemical method. • We examine changes of composition, microstructure, bonding strength and bioactivity of the hydroxyapatite coating. • 48 h is the optimal immersing time. • We

  10. Electrochemical investigation of chromium oxide-coated Ti-6Al-4V and Co-Cr-Mo alloy substrates.

    Science.gov (United States)

    Swaminathan, Viswanathan; Zeng, Haitong; Lawrynowicz, Daniel; Zhang, Zongtao; Gilbert, Jeremy L

    2011-08-01

    Hard coatings for articulating surfaces of total joint replacements may improve the overall wear resistance. However, any coating approach must take account of changes in corrosion behavior. This preliminary assessment analyzes the corrosion kinetics, impedance and mechanical-electrochemical stability of 100 μm thick plasma sprayed chromium oxide (Cr₂O₃) coatings on bearing surfaces in comparison to the native alloy oxide films on Co-Cr-Mo and Ti-6Al-6V. Cyclic potentiodynamic polarization, electrochemical impedance spectroscopy, and mechanical abrasion under potentiostatic conditions were performed on coated and substrate surfaces in physiological saline. SEM analysis characterized the coating morphology. The results showed that the corrosion current density values of chromium oxide coatings (0.4-1.2 μA/cm²) were of the same order of magnitude as Ti-6Al-4V alloy. Mechanical abrasion did not increase corrosion rates of chromium oxide coatings but did for uncoated Co-Cr-Mo and Ti-6Al-4V. The impedance response of chromium oxide coatings was very different than Co-Cr-Mo and Ti-6Al-4V native oxides characterized by a defected coating model. More of a frequency-independent purely resistive response was seen in mid-frequency range for the coatings (CPE(coat) : 40-280 nF/cm² (rad/s)(1-α) , α: 0.67-0.83) whereas a more capacitive character is seen for Co-Cr-Mo and Ti-6Al-4V (CPE(ox) around 20 μF/cm² (rad/s)(1-α) , α around 0.9). Pores, interparticle gaps and incomplete fusion typical for thermal spray coatings were present in these oxides which could have influenced corrosion resistance. The coating microstructure could have allowed some fluid penetration. Overall, these coatings appear to have suitable corrosion properties for wear surfaces. Copyright © 2011 Wiley Periodicals, Inc.

  11. Biomimetic Hydroxyapatite Growth on Functionalized Surfaces of Ti-6Al-4V and Ti-Zr-Nb Alloys

    Science.gov (United States)

    Pylypchuk, Ie V.; Petranovskaya, A. L.; Gorbyk, P. P.; Korduban, A. M.; Markovsky, P. E.; Ivasishin, O. M.

    2015-08-01

    A biomimetic approach for coating titanium-containing alloys with hydroxyapatite (HA) is reported in the article. Two types of Ti-containing alloys were chosen as an object for coating: Ti-6Al-4V (recommended for orthopedic application) and a novel highly biocompatible Ti-Zr-Nb alloy, with good mechanical compatibility due to a modulus that is more close to that of human bones (E ≈ 50 GPa instead of 110 GPa in Ti-6Al-4V). Coating process was carried out in a 10×-concentrated simulated body fluid (SBF)—synthetic analog of human body plasma. The effect of oxidized and carboxylated alloy surface on formation of biomimetic hydroxyapatite has been studied. By XRD, we found influence of thermal conditions on HA crystal formation and size. SEM images and Fourier transform infrared confirmed that hydroxyapatite with different morphology, crystallinity, and Ca/P ratio formed on metallic surfaces. X-ray photoelectron spectroscopy showed that in the Ti-6AL-4V sample the observed Ca/P ratio reach 0.97, whereas in the Ti-Zr-Nb sample the observed Ca/P ratio reach 1.15.

  12. Effects of heat treatment on microstructure and mechanical behaviour of additive manufactured porous Ti6Al4V

    Science.gov (United States)

    Ahmadi, S. M.; Jain, R. K. Ashok Kumar; Zadpoor, A. A.; Ayas, C.; Popovich, V. A.

    2017-12-01

    Titanium and its alloys such as Ti6Al4V play a major role in the medical industry as bone implants. Nowadays, by the aid of additive manufacturing (AM), it is possible to manufacture porous complex structures which mimic human bone. However, AM parts are near net shape and post processing may be needed to improve their mechanical properties. For instance, AM Ti6Al4V samples may be brittle and incapable of withstanding dynamic mechanical loads due to their martensitic microstructure. The aim of this study was to apply two different heat treatment regimes (below and above β-transus) to investigate their effects on the microstructure and mechanical properties of porous Ti6Al4V specimens. After heat treatment, fine acicular α‧ martensitic microstructure was transformed to a mixture of α and β phases. The ductility of the heat-treated specimens, as well as some mechanical properties such as hardness, plateau stress, and first maximum stress changed while the density and elastic gradient of the porous structure remained unchanged.

  13. An investigation of dynamic mechanical behaviour of Ti6Al4V titanium alloy at room temperature

    Directory of Open Access Journals (Sweden)

    Ran Chun

    2016-01-01

    Full Text Available To study the high strain rate shear behaviour of Ti6Al4V titanium alloy, a series of dynamic compression experiments has been performed by split Hopkinson pressure bar (SHPB using Flat Hat-shaped specimen at room temperature. Macro true shear stress-true strain curves were obtained under different strain rate loading conditions at room temperature. The effects of strain hardening and strain rate hardening on the dynamic mechanical properties of Ti6Al4V titanium alloy were discussed. Results indicate that a The higher the strain rate, the higher the flow stress, therefore, the material has obvious strain rate hardening effect, b It is ductile failure for Ti6Al4V titanium alloy under quasi-static loading condition, c For dynamical tests, the values for true shear stress increase with increasing true strain till the maximum true shear stress, on the contrary, the values for true shear stress decrease with increasing the true strain after the maximum true shear stress and d The flow stress increases with increasing the true strain under quasi-static loading condition during the plastic deformation.

  14. Interfacial Reaction During High Energy Ball Milling Dispersion of Carbon Nanotubes into Ti6Al4V

    Science.gov (United States)

    Adegbenjo, A. O.; Olubambi, P. A.; Potgieter, J. H.; Nsiah-Baafi, E.; Shongwe, M. B.

    2017-12-01

    The unique thermal and mechanical properties of carbon nanotubes (CNTs) have made them choice reinforcements for metal matrix composites (MMCs). However, there still remains a critical challenge in achieving homogeneous dispersion of CNTs in metallic matrices. Although high energy ball milling (HEBM) has been reported as an effective method of dispersing CNTs into metal matrices, a careful selection of the milling parameters is important not to compromise the structural integrity of CNTs which may cause interfacial reactions with the matrix. In this study, multi-walled carbon nanotubes (MWCNTs) were purified by annealing in argon and vacuum atmospheres at 1000 and 1800 °C, respectively, for 5 h to remove possible metallic catalyst impurities. Subsequently, 1, 2 and 3 wt.% MWCNTs were dispersed by adapted HEBM into Ti6Al4V alloy metal matrix. Raman spectroscopy (RS), x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectrometry and transmission electron microscopy techniques were used to characterize the as-received and annealed MWCNTs, as well as the admixed MWCNT/Ti6Al4V nanocomposite powders. The experimental results showed that vacuum annealing successfully eliminated retained nickel (Ni) catalysts from MWCNTs, while the adapted HEBM method achieved a relative homogeneous dispersion of MWCNTs into the Ti6Al4V matrix and helped to control interfacial reactions between defective MWCNTs and the metal matrix.

  15. Experimental Investigation on the Fatigue Life of Ti-6Al-4V Treated by Vibratory Stress Relief

    Directory of Open Access Journals (Sweden)

    Han-Jun Gao

    2017-05-01

    Full Text Available Vibratory stress relief (VSR is a highly efficient and low-energy consumption method to relieve and homogenize residual stresses in materials. Thus, the effect of VSR on the fatigue life should be determined. Standard fatigue specimens are fabricated to investigate the fatigue life of Ti-6Al-4V titanium alloy treated by VSR. The dynamic stresses generated under different VSR amplitudes are measured, and then the relationship between the dynamic stress and vibration amplitude is obtained. Different specimen groups are subjected to VSRs with different amplitudes and annealing treatment with typical process parameters. Residual stresses are measured to evaluate the stress relieving effects. Finally, the fatigue behavior under different states is determined by uniaxial tension–compression fatigue experiments. Results show that VSR and annealing treatment have negative effects on the fatigue life of Ti-6Al-4V. The fatigue life is decreased with the increase in VSR amplitude. When the VSR amplitude is less than 0.1 mm, the decrease in fatigue limit is less than 2%. Compared with specimens without VSR or annealing treatment, the fatigue limit of the specimens treated by VSR with 0.2 mm amplitude and annealing treatment decreases by 10.60% and 8.52%, respectively. Although the stress relieving effect is better, high amplitude VSR will lead to the decrease of Ti-6Al-4V fatigue life due to the defects generated during vibration. Low amplitude VSR can effectively relieve the stress with little decrease in fatigue life.

  16. Heat-Treated TiO2 Plasma Spray Deposition for Bioactivity Improvement in Ti-6Al-4V Alloy

    Science.gov (United States)

    Kumari, Renu; Majumdar, Jyotsna Dutta

    2017-12-01

    In the present study, titanium di-oxide (TiO2) coating has been developed on Ti-6Al-4V substrate by plasma spray deposition. Followed by plasma spraying, heat treatment of the sprayed sample has been carried out by isothermally holding it at 823 K (550 °C) for 2 h. Microstructural analysis shows the presence of porosity and unmelted particles on the as-sprayed surface, the area fraction of which reduces after heat treatment. X-ray diffraction analysis shows the phase transformation from anatase (in precursor powder) to rutile (in as-sprayed coating and the same after heat treatment). There is an improvement in nano-hardness, "Young's modulus" and wear resistance in plasma-sprayed TiO2 coating (as-sprayed as well as post-heat-treated condition) as compared to as-received Ti-6Al-4V, though post-heat treatment offers a superior hardness, "young's modulus" and wear resistance as compared to as-sprayed coating. The corrosion behavior in "hank's solution" shows decrease in corrosion resistance after plasma spraying and post-heat treatment as compared to as-received substrate. A significant decrease in contact angle and improvement in bioactivity (in terms of apatite deposition) were observed in TiO2-coated surface as compared to as-received Ti-6Al-4V.

  17. Tribology and hydrophobicity of a biocompatible GPTMS/PFPE coating on Ti6Al4V surfaces.

    Science.gov (United States)

    Panjwani, Bharat; Sinha, Sujeet K

    2012-11-01

    Tribological properties of perfluoropolyether (PFPE) coated 3-glycidoxypropyltrimethoxy silane (GPTMS) SAMs (self-assembled monolayers) onto Ti6Al4V alloy substrate were studied using ball-on-disk experiments. GPTMS SAMs deposition onto a Ti6Al4V alloy surface was carried out using solution phase method. Ultra-thin layer of PFPE was dip-coated onto SAMs modified specimens. Tribological tests were carried out at 0.2 N normal load and rotational speed of 200 rpm using track radius of 2 mm. Wear track and counterface surface conditions were investigated using optical microscopy. PFPE modified specimens were baked at 150 °C for 1h to investigate the effect of thermal treatment on tribological properties. Surface characterization tests such as contact angle measurement, AFM morphology and X-ray photoelectron spectroscopy were carried out for differently modified specimens. PFPE overcoat meets the requirements of cytotoxicity test using the ISO 10993-5 elution method. PFPE top layer lowered the coefficient of friction and increased wear durability for different specimens (with and without GPTMS intermediate layer). PFPE overcoat onto GPTMS showed significant increase in the wear resistance compared with overcoat onto bare Ti6Al4V specimens. The observed improvement in the tribological properties can be attributed to the change in the interaction of PFPE molecules with the substrate surface due to the GPTMS intermediate layer. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Mechanical Properties of Ti-6Al-4V Octahedral Porous Material Unit Formed by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Jianfeng Sun

    2012-01-01

    Full Text Available The Ti-6Al-4V octahedral porous material unit is designed to calculate its load. In this paper, ANSYS is adopted for the load simulation of the unit. And a simplified model of dimensional theoretical calculation is established, by which the analytical equation of the fracture load is obtained and the calculation of the load of Ti-6Al-4V is completed. Moreover, selective laser melting is adopted in processing the Ti-6Al-4V porous material unit. The experimental value of fracture load of this material is obtained through compression experiment. The results show that the simulation curves approximate the variation tendency of the elastic deformation of the compression curves; the curves of theoretical calculation approximate the general variation tendency; and the experimental value of fracture load is very close to the theoretical value. Therefore, the theoretical prediction accuracy of fracture load is high, which lays the foundation for the mechanical properties of the octahedral porous material.

  19. EVIDENCE OF THE SEMI-SOLID FORMATION IN THE MEDICAL GRADE TI6AL4V ALLOY USING INDUCTION HEATING

    Directory of Open Access Journals (Sweden)

    Carlos Roberto Fernandes

    2015-12-01

    Full Text Available One alternative for processing cost reduction with simultaneous improvement of the mechanical properties of the Medical Ti6Al4V alloy is to get its semi-solid feedstock with a non-dendritic microstructure for further processing. The purpose of the present work is to evaluate the possibility of obtaining a semi-solid Ti6Al4V alloy by heating it up from the room temperature to the range temperature between the lines solidus and liquidus, using induction heating. The Ti6Al4V billets underwent heat treatment and quenching for semi-solid formation using a designed device and specific time pulsed profile. The billet temperature reached 1630 oC, and after the cooling rate of 54 oC/s, some samples formed a globular phase characteristic of the semi-solid alloy. This study shows that it is possible to get a semi-solid microstructure of this alloy starting from its solid state.

  20. EFFECT OF SHORT HEAT TREATMENT ROUTES ON THE TRIBOLOGICAL PROPERTIES OF TI-6AL-4V ALLOY

    Directory of Open Access Journals (Sweden)

    N. Nikoogoftar

    2017-09-01

    Full Text Available In this research, the effect of annealing and aging temperature as well as the effect of quenching media on the microstructure, hardness and dry sliding wear behavior of Ti-6Al-4V alloy has been studied. Cylindrical samples with the diameter of 10 mm and the height of 20mm were solutionized at 930˚C and 1060˚C for 600 seconds and then were quenched in the cold water and in the air. The samples were aged at different temperature of 480˚C, 550˚C and 610˚C for 360 s to increase the hardness. Heat treated samples were tested using standard pin-on-disc test machine at the applied loads of 100, 150 and 200 N. Microstructural investigations using scanning electron microscope revealed that for the samples solutionized at 930˚C and quenched in the water, the microstructure is composed of primary α and high volume fraction of martensitic α΄ phase with fine precipitated of β between martensitic lathes. In the case of air cooled samples, transformed β has also been  appeared in the vicinity of primary α. For the samples solutionized at 1060˚C and quenched in the water, fully martensitic micro structure with fine β precipitates was observed. For the sample solutionized at 1060˚C and air quenched, plate like α and lamellar grain boundary β were detected. The maximum hardness value relates to the sample solutionized at 1060˚C and quenched in water which is equal to 433 HV. Different wear mechanisms, including oxidative wear, scratch, and delamination occurred at the worn surfaces at different applied loads. For the samples quenched in the water, the oxidative wear mechanism governing at low applied load and oxide debris was observed as separate or compacted particles which formed in the contact between pin and steel counter face detached from the sample. At higher applied loads, delamination and scratch mechanism was also observed and metallic plate like debris was detached from the sample. Mechanically mixed layer (MML was formed on the

  1. Microhardness and wear behaviour of surface modified Ti6Al4V/Zr-TiC metal matrix composite for advanced material

    CSIR Research Space (South Africa)

    Popoola, API

    2012-12-01

    Full Text Available Surface modification of titanium alloy (Ti-6Al-4V) was made using a Rofin Sinar 4 kW Nd: YAG laser. A laser multi-track 50% overlapping process was employed to produce Zr and Zr-TiC metal matrix composite (MMC) coatings on Ti6Al4V substrate...

  2. Heat treatment of Ti6Al4V produced by Selective Laser Melting: Microstructure and mechanical properties

    International Nuclear Information System (INIS)

    Vrancken, Bey; Thijs, Lore; Kruth, Jean-Pierre; Van Humbeeck, Jan

    2012-01-01

    Highlights: ► Responses of SLM-produced and wrought Ti6Al4V to heat treatment are compared. ► Temperature is found to be the controlling parameter for treatments in the α + β range. ► Ductility could be improved by a factor of 85%, from 7.27% to 13.59%. ► An optimal heat treatment for SLM produced Ti6Al4V is proposed. - Abstract: The present work shows that optimization of mechanical properties via heat treatment of parts produced by Selective Laser Melting (SLM) is profoundly different compared to conventionally processed Ti6Al4V. In order to obtain optimal mechanical properties, specific treatments are necessary due to the specific microstructure resulting from the SLM process. SLM is an additive manufacturing technique through which components are built by selectively melting powder layers with a focused laser beam. The process is characterized by short laser-powder interaction times and localized high heat input, which leads to steep thermal gradients, rapid solidification and fast cooling. In this research, the effect of several heat treatments on the microstructure and mechanical properties of Ti6Al4V processed by SLM is studied. A comparison is made with the effect of these treatments on hot forged and subsequently mill annealed Ti6Al4V with an original equiaxed microstructure. For SLM produced parts, the original martensite α′ phase is converted to a lamellar mixture of α and β for heat treating temperatures below the β-transus (995 °C), but features of the original microstructure are maintained. Treated above the β-transus, extensive grain growth occurs and large β grains are formed which transform to lamellar α + β upon cooling. Post treating at 850 °C for 2 h, followed by furnace cooling increased the ductility of SLM parts to 12.84 ± 1.36%, compared to 7.36 ± 1.32% for as-built parts.

  3. Fixation of bioactive calcium alkali phosphate on Ti6Al4V implant material with femtosecond laser pulses

    International Nuclear Information System (INIS)

    Symietz, Christian; Lehmann, Erhard; Gildenhaar, Renate; Koter, Robert; Berger, Georg; Krueger, Joerg

    2011-01-01

    Bone implants made of metal, often titanium or the titanium alloy Ti6Al4V, need to be surface treated to become bioactive. This enables the formation of a firm and durable connection of the prosthesis with the living bone. We present a new method to uniformly cover Ti6Al4V with a thin layer of ceramics that imitates bone material. These calcium alkali phosphates, called GB14 and Ca10, are applied to the metal by dip coating of metal plates into an aqueous slurry containing the fine ceramic powder. The dried samples are illuminated with the 790 nm radiation of a pulsed femtosecond laser. If the laser fluence is set to a value just below the ablation threshold of the ceramic (ca. 0.4 J/cm 2 ) the 30 fs laser pulses penetrate the partly transparent ceramic layer of 20-40 μm thickness. The remaining laser fluence at the ceramic-metal interface is still high enough to generate a thin metal melt layer leading to the ceramic fixation on the metal. The laser processing step is only possible because Ti6Al4V has a lower ablation threshold (between 0.1 and 0.15 J/cm 2 ) than the ceramic material. After laser treatment in a fluence range between 0.1 and 0.4 J/cm 2 , only the particles in contact with the metal withstand a post-laser treatment (ultrasonic cleaning). The non-irradiated rest of the layer is washed off. In this work, we present results of a successful ceramic fixation extending over larger areas. This is fundamental for future applications of arbitrarily shaped implants.

  4. Electrochemical characterization of albumin protein on Ti-6AL-4V alloy immersed in a simulated plasma solution.

    Science.gov (United States)

    Padilla, Norma; Bronson, Arturo

    2007-06-01

    The effect of oxygen and albumin on the electrochemical behavior of a Ti-6Al-4V alloy immersed in a simulated inorganic plasma (SIP) solution was studied with a rotating-cylindrical electrode configuration to focus on the surface/electrolyte reactions. Potentiokinetic scans and electrochemical impedance spectroscopy have been used to characterize the interface by determining the passive current density and capacitance. For the polarization scans, an albumin addition of 37.7 mg/cm(3) to the SIP solution (oxygenated and unoxygenated) decreased the passive current density, indicating a lowering of the corrosive rate. The surface capacitance for the Ti-6Al-4V alloy immersed in a SIP solution averaged 13 microF/cm(2), which transformed after albumin addition (37.7 mg/cm(3)) from a potential independent behavior to the capacitance ranging from 23 to 6 microF/cm(2) with increasing potentials from -800 to 1500 mV(SCE), respectively, indicative of albumin adsorption. Within the same potential range and albumin addition to oxygenated solutions, the capacitances expanded slightly with a similar decreasing trend from 31 to 6 microF/cm(2), although the capacitance depicts an interaction between the hydrated passive film and the adsorbed albumin from -550 to 500 mV(SCE) in which the capacitance plateaued at 15 microF/cm(2). The hydrated porous oxide film results from the porous rutile layer reacting with H(2)O(2) formed as an intermediary component of oxygen reduction at the Ti-6Al-4V surface. The passive film-albumin interaction would affect the processing of titanium alloys in their surface preparation for biocompatibility, as well as determining the reactivity of titanium alloys to proteins.

  5. Functionalisation of Ti6Al4V components fabricated using selective laser melting with a bioactive compound

    Energy Technology Data Exchange (ETDEWEB)

    Vaithilingam, Jayasheelan [Additive Manufacturing and 3D Printing Research Group, School of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Kilsby, Samuel [Department of Chemistry, Loughborough University, Loughborough LE11 3TU (United Kingdom); Goodridge, Ruth D., E-mail: Ruth.Goodridge@nottingham.ac.uk [Additive Manufacturing and 3D Printing Research Group, School of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Christie, Steven D.R. [Department of Chemistry, Loughborough University, Loughborough LE11 3TU (United Kingdom); Edmondson, Steve [School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Hague, Richard J.M. [Additive Manufacturing and 3D Printing Research Group, School of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2015-01-01

    Surface modification of an implant with a biomolecule is used to improve its biocompatibility and to reduce post-implant complications. In this study, a novel approach has been used to functionalise phosphonic acid monolayers with a drug. Ti6Al4V components fabricated using selective laser melting (SLM) were functionalised with Paracetamol (a pharmaceutically relevant biomolecule) using phosphonic acid based self-assembled monolayers (SAMs). The attachment, stability of the monolayers on the SLM fabricated surface and functionalisation of SAMs with Paracetamol were studied using X-ray photoelectron spectroscopy (XPS) and surface wettability measurements. The obtained results confirmed that SAMs were stable on the Ti6Al4V surface for over four weeks and then began to desorb from the surface. The reaction used to functionalise the phosphonic acid monolayers with Paracetamol was noted to be successful. Thus, the proposed method has the potential to immobilise drugs/proteins to SAM coated surfaces and improve their biocompatibility and reduce post-implant complications. - Graphical abstract: A significant change in the contact angle confirming the immobilisation of Paracetamol. (a) Before self-assembled monolayer (SAM) attachment, (b) after SAM attachment and (c) after the immobilisation of Paracetamol to the SAMs. - Highlights: • Ti6Al4V parts were fabricated using selective laser melting (SLM). • Monolayers used to modify the SLM surface were stable for over 28 days (in-vitro). • Surface roughness did not have a significant impact on the monolayer stability. • Paracetamol was successfully immobilised to the adsorbed monolayers. • Caution required before selecting Paracetamol as a model drug.

  6. Commercially pure titanium (cp-Ti) versus titanium alloy (Ti6Al4V) materials as bone anchored implants - Is one truly better than the other?

    Science.gov (United States)

    Shah, Furqan A; Trobos, Margarita; Thomsen, Peter; Palmquist, Anders

    2016-05-01

    Commercially pure titanium (cp-Ti) and titanium alloys (typically Ti6Al4V) display excellent corrosion resistance and biocompatibility. Although the chemical composition and topography are considered important, the mechanical properties of the material and the loading conditions in the host have, conventionally, influenced material selection for different clinical applications: predominantly Ti6Al4V in orthopaedics while cp-Ti in dentistry. This paper attempts to address three important questions: (i) To what extent do the surface properties differ when cp-Ti and Ti6Al4V materials are manufactured with the same processing technique?, (ii) Does bone tissue respond differently to the two materials, and (iii) Do bacteria responsible for causing biomaterial-associated infections respond differently to the two materials? It is concluded that: (i) Machined cp-Ti and Ti6Al4V exhibit similar surface morphology, topography, phase composition and chemistry, (ii) Under experimental conditions, cp-Ti and Ti6Al4V demonstrate similar osseointegration and biomechanical anchorage, and (iii) Experiments in vitro fail to disclose differences between cp-Ti and Ti6Al4V to harbour Staphylococcus epidermidis growth. No clinical comparative studies exist which could determine if long-term, clinical differences exist between the two types of bulk materials. It is debatable whether cp-Ti or Ti6Al4V exhibit superiority over the other, and further comparative studies, particularly in a clinical setting, are required. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Corrosion Behavior of Ti-13Nb-13Zr and Ti-6Al-4V Alloys for Biomaterial Application

    Energy Technology Data Exchange (ETDEWEB)

    Saji, Viswanathan S.; Jeong, Yong Hoon; Choe, Han Cheol [Chosun University, Gwangju (Korea, Republic of); Yu, Jin Woo [Shingyeong University, Hwaseong (Korea, Republic of)

    2010-02-15

    Ti-13Nb-13Zr (TNZ) alloy has attracted considerable research attention in the last decade as a suitable substitute for the commercially used Ti-6Al-4V (TAV) alloy for orthopedic and dental implant applications. Hence, in the present work, a comparative evaluation has been performed on the electrochemical corrosion behavior of TNZ and TAV alloys in 0.9 wt.% NaCl solution. The result of the study showed that both the alloys had similar electrochemical behavior. The corrosion resistance of TAV alloy is found to be marginally superior to that of TNZ alloy.

  8. The Possibility Of Use Of Laser-Modified Ti6Al4V Alloy In Friction Pairs In Endoprostheses

    Directory of Open Access Journals (Sweden)

    Majkowska B.

    2015-06-01

    Full Text Available The purpose of this paper is to show results of laser treatment at cryogenic conditions of the Ti6Al4V alloy used for orthopedic applications. That modification process ought to bring beneficial changes of microstructure and residual stresses in the surface layer. The paper presents the abrasive wear of the base and laser remelted material in association with ceramics Al2O3. Despite the surface cracking after laser treatment the tribological properties in simulated body fluid have been substantially improved.

  9. Tool Wear Prediction in Ti-6Al-4V Machining through Multiple Sensor Monitoring and PCA Features Pattern Recognition

    OpenAIRE

    Alessandra Caggiano

    2018-01-01

    Machining of titanium alloys is characterised by extremely rapid tool wear due to the high cutting temperature and the strong adhesion at the tool-chip and tool-workpiece interface, caused by the low thermal conductivity and high chemical reactivity of Ti alloys. With the aim to monitor the tool conditions during dry turning of Ti-6Al-4V alloy, a machine learning procedure based on the acquisition and processing of cutting force, acoustic emission and vibration sensor signals during turning i...

  10. Structural characterization of the metal/glass interface in bioactive glass coatings on Ti-6Al-4V

    Energy Technology Data Exchange (ETDEWEB)

    Oku, T.; Suganuma, K.; Wallemberg, L.R.; Tomsia, A.P.; Gomez-Vega, J.M.; Saiz, E.

    1999-12-01

    Coating Ti-based implants with bioactive materials promotes joining between the prostheses and the bone as well as increasing long-term implant stability. In the present work, the interface between Ti-6Al-4V and bioactive silicate glass coatings, prepared using a simple enameling technique, is analyzed. High-resolution transmission electron microscopy of the glass/alloy interface shows the formation of a reaction layer ({approx}150 nm thick) composed of Ti5Si3 nanoparticles with a size of {approx}20 nm. This nanostructured interface facilitates the formation of a stable joint between the glass coating and the alloy.

  11. Data on the surface morphology of additively manufactured Ti-6Al-4V implants during processing by plasma electrolytic oxidation

    Directory of Open Access Journals (Sweden)

    Ingmar A.J. van Hengel

    2017-08-01

    Full Text Available Additively manufactured Ti-6Al-4V implants were biofunctionalized using plasma electrolytic oxidation. At various time points during this process scanning electron microscopy imaging was performed to analyze the surface morphology (van Hengel et al., 2017 [1]. This data shows the changes in surface morphology during plasma electrolytic oxidation. Data presented in this article are related to the research article “Selective laser melting porous metallic implants with immobilized silver nanoparticles kill and prevent biofilm formation by methicillin-resistant Staphylococcus aureus” (van Hengel et al., 2017 [1].

  12. Fabrication and Evaluation of Welded Ti-6Al-4V Test Sections

    National Research Council Canada - National Science Library

    Grendahl, Scott

    2001-01-01

    ... material for the Ml Abrams turret glacis as opposed to the presently utilized RHA steel. Two turret glacis test sections were fabricated from Ti-6A1-4V armor plate, and one was fabricated from RHA steel...

  13. In situ observations of lattice expansion and transformation rates of α and β phases in Ti-6Al-4V

    International Nuclear Information System (INIS)

    Elmer, J.W.; Palmer, T.A.; Babu, S.S.; Specht, E.D.

    2005-01-01

    In situ X-ray diffraction experiments using synchrotron radiation were performed on Ti-6Al-4V samples to directly observe the α → β phase transformation during heating. These experiments were conducted at the Advanced Photon Source (APS) using a 30 keV synchrotron X-ray beam to monitor changes in the α and β phases as a function of heating time under different heating rates. The results were compared to computational thermodynamic predictions of the phase fractions versus temperature, providing information about the kinetics of the α → β transformation in Ti-6Al-4V. The measured transformation rates were shown to be consistent with a diffusion-controlled growth mechanism, whereby diffusion of V in the β-Ti phase controls the rate. Based on the X-ray diffraction data, real time measurements of the α and β phase lattice parameters were made. Dramatic differences were observed in the changes of the lattice parameters of the two phases during the transformation. These changes are believed to be due to the partitioning of V and its strong effect on the lattice parameter of the β phase. An unexpected contraction of the lattice parameter of the β phase was further observed during heating in the temperature range between 500 and 600 deg. C. The origin of this contraction is most likely related to the annealing of residual stresses created by the different thermal expansion behaviors of the two phases

  14. Electrochemical behavior of Ti and Ti6Al4V in aqueous solutions of citric acid containing halides

    Directory of Open Access Journals (Sweden)

    Anelise Marlene Schmidt

    2006-12-01

    Full Text Available This paper reports on an investigation of the electrochemical behavior of Ti grade 2 and Ti6Al4V alloy in aqueous citric acid solutions with pH 2.0 containing halide ions. Voltammetric studies of Ti and the alloy in citric acid, with and without chloride ions, indicate that the Ti and Ti alloy presented a passive behavior in the test solutions used. Pitting was observed at 3.0 and 2.5 V/SCE for Ti and Ti6Al4V, respectively, when bromide ions were added to the solution. In solutions containing fluoride ions, dissolution of the film occurred at potentials close to - 1.0 V/SCE in both electrodes. The iodide ions oxidized on the passive oxide film at potentials close to 1.0 V/SCE. EIS results of the materials in citric acid solutions containing chloride ions revealed that the film's resistance increased as the applied potential rose from 0 to 1.0 V. In bromide-containing solutions, breakdown of the film was confirmed at potentials above 2.0 V/SCE in both electrodes. These results suggest film reformation for Ti and the alloy in solutions containing fluoride at potentials within the passive region.

  15. Surface treatment by electric discharge machining of Ti-6Al-4V alloy for potential application in orthopaedics.

    Science.gov (United States)

    Harcuba, Petr; Bačáková, Lucie; Stráský, Josef; Bačáková, Markéta; Novotná, Katarína; Janeček, Miloš

    2012-03-01

    This study investigated the properties of Ti-6Al-4V alloy after surface treatment by the electric discharge machining (EDM) process. The EDM process with high peak currents proved to induce surface macro-roughness and to cause chemical changes to the surface. Evaluations were made of the mechanical properties by means of tensile tests, and of surface roughness for different peak currents of the EDM process. The EDM process with peak current of 29 A was found to induce sufficient surface roughness, and to have a low adverse effect on tensile properties. The chemical changes were studied by scanning electron microscopy equipped with an energy dispersive X-ray analyser (EDX). The surface of the benchmark samples was obtained by plasma-spraying a titanium dioxide coating. An investigation of the biocompatibility of the surface-treated Ti-6Al-4V samples in cultures of human osteoblast-like MG 63 cells revealed that the samples modified by EDM provided better substrates for the adhesion, growth and viability of MG 63 cells than the TiO2 coated surface. Thus, EDM treatment can be considered as a promising surface modification to orthopaedic implants, in which good integration with the surrounding bone tissue is required. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Estudio mediante SEM/EDS del taladrado en seco de la aleación Ti-6Al-4V

    Directory of Open Access Journals (Sweden)

    Cantero, J. L.

    2005-12-01

    Full Text Available This paper is focused on dry drilling of Ti6Al4V. In absence of cutting fluid, high temperatures are reached. Two different cutting conditions are studied in order to analyze the influence of temperature. In first condition, tests with no pause between drilled holes were carried out. In second condition, tests were performed cooling the tool with air between consecutively holes. Tool wear was studied with optical microscope and SEM-EDS techniques. he quality of machined holes was estimated in terms of optical inspection. Significantly differences in tool wear evolution were observed between both cutting conditions analysed.

    En este artículo se estudia el proceso de taladrado sin fluido de corte, de la aleación Ti6Al4V, comparando dos condiciones de mecanizado, con y sin enfriamiento de herramienta y material entre taladros. El objetivo de este trabajo es analizar la influencia en el desgaste de la herramienta y en la calidad del agujero, del diferente incremento de temperatura originado por trabajar en una u otra condición. Para ello, se realizará análisis SEM/EDS y microscopía óptica de la broca e inspección visual del material.

  17. Characteristics of surface modified Ti-6Al-4V alloy by a series of YAG laser irradiation

    Science.gov (United States)

    Zeng, Xian; Wang, Wenqin; Yamaguchi, Tomiko; Nishio, Kazumasa

    2018-01-01

    In this study, a double-layer Ti (C, N) film was successfully prepared on Ti-6Al-4V alloy by a series of YAG laser irradiation in nitrogen atmosphere, aiming at improving the wear resistance. The effects of laser irradiation pass upon surface chemical composition, microstructures and hardness were investigated. The results showed that the surface chemicals were independent from laser irradiation pass, which the up layer of film was a mixture of TiN and TiC0.3N0.7, and the down layer was nitrogen-rich α-Ti. Both the surface roughness and hardness increased as raising the irradiation passes. However, surface deformation and cracks happened in the case above 3 passes' irradiation. The wear resistance of laser modified sample by 3 passes was improved approximately by 37 times compared to the as received substrate. Moreover, the cytotoxic V ion released from laser modified sample was less than that of as received Ti-6Al-4V alloy in SBF, suggesting the potentiality of a new try to modify the sliding part of Ti-based hard tissue implants in future biomedical application.

  18. Effects of laser shock peening with contacting foil on micro laser texturing surface of Ti6Al4V

    Science.gov (United States)

    Dai, Fengze; Zhang, Zidong; Ren, Xudong; Lu, Jinzhong; Huang, Shu

    2018-02-01

    Ti6Al4V samples with micro-dimple arrays were subjected to laser shock peening in contact with foil (HCLSP). The surface roughness, micro-hardness, the residual stress distribution and the surface morphology of the micro-dimple arrays were studied to evaluate the effects of HCLSP. Moreover, the surface topography of the foils in contact was also analyzed. The gap existence between the foil and the to-be treated surface led the mechanism of HCLSP to be different compared to regular laser shock peening. The surface roughness reduction, the work-hardening effects, the compressive residual stress and the micro crack enclosure were achieved. A simplified ball-hitting-surface model was utilized to analyze the HCLSP impact. The model could well explain the experimental results. When treated by the HCLSP with H62 foil at the laser power density of 4.24 GW/cm2, the Ti6Al4V samples with micro-dimple arrays exhibit well surface topography and mechanical performance.

  19. Further Investigation Into the Use of Laser Surface Preparation of Ti-6Al-4V Alloy for Adhesive Bonding

    Science.gov (United States)

    Palmieri, Frank L.; Crow, Allison; Zetterberg, Anna; Hopkins, John; Wohl, Christopher J.; Connell, John W.; Belcher, Tony; Blohowiak, Kay Y.

    2014-01-01

    Adhesive bonding offers many advantages over mechanical fastening, but requires robust materials and processing methodologies before it can be incorporated in primary structures for aerospace applications. Surface preparation is widely recognized as one of the key steps to producing robust and predictable bonds. This report documents an ongoing investigation of a surface preparation technique based on Nd:YAG laser ablation as a replacement for the chemical etch and/or abrasive processes currently applied to Ti-6Al-4V alloys. Laser ablation imparts both topographical and chemical changes to a surface that can lead to increased bond durability. A laser based process provides an alternative to chemical-immersion, manual abrasion, and grit blast process steps which are expensive, hazardous, environmentally unfriendly, and less precise. In addition, laser ablation is amenable to process automation, which can improve reproducibility to meet quality standards for surface preparation. An update on work involving adhesive property testing, surface characterization, surface stability, and the effect of laser surface treatment on fatigue behavior is presented. Based on the tests conducted, laser surface treatment is a viable replacement for the immersion chemical surface treatment processes. Testing also showed that the fatigue behavior of the Ti-6Al-4V alloy is comparable for surfaces treated with either laser ablation or chemical surface treatment.

  20. Numerical simulation and experimental investigation of Ti-6Al-4V melted by CW fiber laser at different pressures

    Science.gov (United States)

    Tabassum, Aasma; Zhou, Jie; Han, Bing; Ni, Xiao-wu; Sardar, Maryam

    2017-07-01

    The interaction of continuous wave (CW) fiber laser with Ti-6Al-4V alloy is investigated numerically and experimentally at different laser fluence values and ambient pressures of N2 atmosphere to determine the melting time threshold of Ti-6Al-4V alloy. A 2D-axisymmetric numerical model considering heat transfer and laminar flow is established to describe the melting process. The simulation results indicate that material melts earlier at lower pressure (8.0 Pa) than at higher pressure (8.8×104 Pa) in several milliseconds with the same laser fluence. The experimental results demonstrate that the melting time threshold at high laser fluence (above 1.89×108 W/m2) is shorter for lower pressure (vacuum), which is consistent with the simulation. While the melting time threshold at low laser fluence (below 1.89×108 W/m2) is shorter for higher pressure. The possible aspects which can affect the melting process include the increased heat loss induced by the heat conduction between the metal surface and the ambient gas with the increased pressure, and the absorption variation of the coarse surface resulted from the chemical reaction.

  1. Cutting zone area and chip morphology in high-speed cutting of titanium alloy Ti-6Al-4V

    International Nuclear Information System (INIS)

    Ke, Qing Chan; Xu, Daochun; Xiong, Dan Ping

    2017-01-01

    The titanium alloy Ti-6Al-4V has superior properties but poor machinability, yet is widely used in aerospace and biomedical industries. Chip formation and cutting zone area are important factors that have received limited attention. Thus, we propose a high-speed orthogonal cutting model for serrated chip formation. The high speed orthogonal cutting of Ti-6Al-4V was studied with a cutting speed of 10-160 m/min and a feed of 0.07-0.11 mm/r. Using theoretical models and experimental results, parameters such as chip shape, serration level, slip angle, and shear slip distance were investigated. Cutting zone boundaries (tool-chip contact length, length of shear plane, and critical slip plane) and cutting zone area were obtained. The results showed that discontinuous, long-curling, and continuous chips were formed at low, medium, and high speeds, respectively. Serration level, shear slip distance, and slip angle rose with increasing cutting speed. The length of shear plane, tool-chip contact, and critical slip plane varied subtly with increased cutting speed, and rose noticeably with increased feed. Cutting zone area grew weakly with increased cutting speed, levelling off at high cutting speed; however, it rose noticeably with increased feed. This study furthers our understanding of the shear slip phenomenon and the mechanism of serrated chip formation

  2. Strain localization during tensile Hopkinson bar testing of commercially pure titanium and Ti6Al4V titanium alloy

    Directory of Open Access Journals (Sweden)

    Moćko Wojciech

    2015-01-01

    Full Text Available The goal of the analysis was to determine the strain localization for various specimen shapes (type A and type B according to PN-EN ISO 26203-1 standard and different loading conditions, i.e. quasi- static and dynamic. Commercially pure titanium (Grade 2 and titanium alloy Ti6Al4V (Grade 5 were selected for the tests. Tensile loadings were applied out using servo-hydraulic testing machine and tensile Hopkinson bar with pre-tension. The results were recorded using ARAMIS system cameras and fast camera Phantom V1210, respectively at quasi-static and dynamic loading conditions. Further, specimens outline was determined on the basis of video data using TEMA MOTION software. The strain distribution on the specimen surface was estimated using digital image correlation method. The larger radius present in the specimen of type B in comparison to specimen of type A, results in slight increase of the elongation for commercially pure titanium at both quasi-static and dynamic loading conditions. However this effect disappears for Ti6Al4V alloy. The increase of the elongation corresponds to the stronger necking effect. Material softening due to increase of temperature induced by plastic work was observed at dynamic loading conditions. Moreover lower elongation at fracture point was found at high strain rates for both materials.

  3. Interface microstructure of the brazed zirconia and Ti-6Al-4V using Ti-based amorphous filler

    Directory of Open Access Journals (Sweden)

    Liu Y.

    2013-01-01

    Full Text Available The polycrystalline ZrO2−3mol.%Y2O3 was brazed to Ti-6Al-4V using a Ti47Zr28Cu14Ni11 (at.% amorphous ribbon at 1123 K in a high vacuum. The microstructure of the interface and evolution mechanism of the joint was investigated. The experimental result showed that the typical interfacial microstructures of the joints consisted of ZrO2/TiO+TiO2+Cu2Ti4O+Ni2Ti4O/α-Ti+(Ti,Zr2(Cu,Ni eutectic/(Ti,Zr2(Cu,Ni/acicular Widmanstäten structure/Ti-6Al-4V alloy. The microstructure of the brazed joint was related to the solution and chemical reaction among atoms during brazing. According to the mechanical property tests the joint brazed at 1123 K for 30 min obtained the maximum shear strength 63 MPa. Both the white block intermetallic compound (Ti,Zr2(Cu,Ni and the coarse α-Ti+(Ti,Zr2(Cu,Ni eutectic structure should be avoided forming in the brazed joint.

  4. Cutting zone area and chip morphology in high-speed cutting of titanium alloy Ti-6Al-4V

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Qing Chan; Xu, Daochun; Xiong, Dan Ping [School of Technology, Beijing Forestry University, Beijing (China)

    2017-01-15

    The titanium alloy Ti-6Al-4V has superior properties but poor machinability, yet is widely used in aerospace and biomedical industries. Chip formation and cutting zone area are important factors that have received limited attention. Thus, we propose a high-speed orthogonal cutting model for serrated chip formation. The high speed orthogonal cutting of Ti-6Al-4V was studied with a cutting speed of 10-160 m/min and a feed of 0.07-0.11 mm/r. Using theoretical models and experimental results, parameters such as chip shape, serration level, slip angle, and shear slip distance were investigated. Cutting zone boundaries (tool-chip contact length, length of shear plane, and critical slip plane) and cutting zone area were obtained. The results showed that discontinuous, long-curling, and continuous chips were formed at low, medium, and high speeds, respectively. Serration level, shear slip distance, and slip angle rose with increasing cutting speed. The length of shear plane, tool-chip contact, and critical slip plane varied subtly with increased cutting speed, and rose noticeably with increased feed. Cutting zone area grew weakly with increased cutting speed, levelling off at high cutting speed; however, it rose noticeably with increased feed. This study furthers our understanding of the shear slip phenomenon and the mechanism of serrated chip formation.

  5. Fiber damage during the consolidation of PVD Ti-6Al-4V coated NEXTEL 610 trademark alumina fibers

    International Nuclear Information System (INIS)

    Warren, J.; Elzey, D.M.; Wadley, H.N.G.

    1995-01-01

    Titanium matrix composites reinforced with sol-gel synthesized α-alumina fiber tows have attracted interest as a potentially low cost continuous fiber reinforced metal matrix composite system. The authors have conducted a detailed investigation of fiber damage during high temperature consolidation of PVD Ti-6Al-4V metallized sol-gel alumina fiber tows. Using both hot isostatic pressing and interrupted vacuum hot press consolidation cycles, the two principal mechanisms of fiber damage have been experimentally identified to be microbending/fracture and fiber matrix reaction. A time dependent micromechanics model incorporating the evolving geometry and mechanical properties of both the fibers and matrix has been formulated to simulate the fiber bending/failure mechanism in a representative unit cell and explore the effect of fiber strength loss due to reaction with the matrix. This model has been used to design a process cycle that minimizes damage by exploiting the enhanced superplastic deformation of the initially nanocrystalline PVD Ti-6Al-4V matrix

  6. Blood Compatibility of ZrO2 Particle Reinforced PEEK Coatings on Ti6Al4V Substrates

    Directory of Open Access Journals (Sweden)

    Jian Song

    2017-11-01

    Full Text Available Titanium (Ti and its alloys are widely used in biomedical devices. As biomaterials, the blood compatibility of Ti and its alloys is important and needs to be further improved to provide better functionality. In this work, we studied the suitability of zirconia (ZrO2 particle reinforced poly-ether-ether-ketone (PEEK coatings on Ti6Al4V substrates for blood-contacting implants. The wettability, surface roughness and elastic modulus of the coatings were examined. Blood compatibility tests were conducted by erythrocytes observation, hemolysis assay and clotting time of recalcified human plasma, to find out correlations between the microstructure of the ZrO2-filled PEEK composite coatings and their blood compatibilities. The results suggested that adding ZrO2 nanoparticles increased the surface roughness and improved the wettability and Derjaguin-Muller-Toporov (DMT elastic modulus of PEEK coating. The PEEK composite matrix coated Ti6Al4V specimens did not cause any aggregation of erythrocytes, showing morphological normal shapes. The hemolysis rate (HR values of the tested specimens were much less than 5% according to ISO 10993-4 standard. The values of plasma recalcification time (PRT of the tested specimens varied with the increasing amount of ZrO2 nanoparticles. Based on the results obtained, 10 wt % ZrO2 particle reinforced PEEK coating has demonstrated an optimum blood compatibility, and can be considered as a candidate to improve the performance of existing PEEK based coatings on titanium substrates.

  7. Functionalisation of Ti6Al4V components fabricated using selective laser melting with a bioactive compound.

    Science.gov (United States)

    Vaithilingam, Jayasheelan; Kilsby, Samuel; Goodridge, Ruth D; Christie, Steven D R; Edmondson, Steve; Hague, Richard J M

    2015-01-01

    Surface modification of an implant with a biomolecule is used to improve its biocompatibility and to reduce post-implant complications. In this study, a novel approach has been used to functionalise phosphonic acid monolayers with a drug. Ti6Al4V components fabricated using selective laser melting (SLM) were functionalised with Paracetamol (a pharmaceutically relevant biomolecule) using phosphonic acid based self-assembled monolayers (SAMs). The attachment, stability of the monolayers on the SLM fabricated surface and functionalisation of SAMs with Paracetamol were studied using X-ray photoelectron spectroscopy (XPS) and surface wettability measurements. The obtained results confirmed that SAMs were stable on the Ti6Al4V surface for over four weeks and then began to desorb from the surface. The reaction used to functionalise the phosphonic acid monolayers with Paracetamol was noted to be successful. Thus, the proposed method has the potential to immobilise drugs/proteins to SAM coated surfaces and improve their biocompatibility and reduce post-implant complications. Copyright © 2014. Published by Elsevier B.V.

  8. Investigation and Optimization of Disk-Laser Welding of 1 mm Thick Ti-6Al-4V Titanium Alloy Sheets

    Directory of Open Access Journals (Sweden)

    Fabrizia Caiazzo

    2015-01-01

    Full Text Available Ti-6Al-4V joints are employed in nuclear engineering, civil industry, military, and space vehicles. Laser beam welding has been proven to be promising, thanks to increased penetration depth and reduction of possible defects of the welding bead; moreover, a smaller grain size in the fusion zone is better in comparison to either TIG or plasma arc welding, thus providing an increase in tensile strength of any welded structures. In this frame, the regression models for a number of crucial responses are discussed in this paper. The study has been conducted on 1 mm thick Ti-6Al-4V plates in square butt welding configuration; a disk-laser source has been used. A three-level Box-Behnken experimental design is considered. An optimum condition is then suggested via numerical optimization with the response surface method using desirability functions with proper weights and importance of constraints. Eventually, Vickers microhardness testing has been conducted to discuss structural changes in fusion and heat affected zone due to welding thermal cycles.

  9. Influence of slight microstructural gradients on the surface properties of Ti6Al4V irradiated by UV

    International Nuclear Information System (INIS)

    Gallardo-Moreno, A.M.; Multigner, M.; Pacha-Olivenza, M.A.; Lieblich, M.; Jimenez, J.A.; Gonzalez-Carrasco, J.L.; Gonzalez-Martin, M.L.

    2009-01-01

    Ti6Al4V alloy is one of the most widely used materials for biomedical implants. Among its properties, it is remarkable the photoactivity displayed by its passive layer, which is mainly composed by titanium dioxide. However, variations in the processing conditions may yield to differences in the microstructure which can be reflected on the surface properties of the machined product. From contact angle measurements taken on different zones of samples removed from a commercial bar of Ti6Al4V, it has been shown that the modifications of the surface Gibbs energy suffered by the alloy under UV irradiation have a radial dependence. This behaviour is related to slight microstructural changes of the alloy, particularly with an increase in the volume fraction of the β-phase when moving to the interior of the sample, which alters the composition and/or microstructure of the passive layer along its radius. This study shows that gradients in the microstructure and physical properties are sample size dependent and are likely related to thermal gradients during processing.

  10. Protective Sliding Carbon-Based Nanolayers Prepared by Argon or Nitrogen Ion-Beam Assisted Deposition on Ti6Al4V Alloy

    Czech Academy of Sciences Publication Activity Database

    Vlčák, P.; Jirka, Ivan

    2016-01-01

    Roč. 2016, č. 2016 (2016), 1697090 ISSN 1687-4110 Institutional support: RVO:61388955 Keywords : carbon-based nanolayers * Ti6Al4V * nanotechnology Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.871, year: 2016

  11. Microstructural Evolution of Commercial-Purity Ti and Superplasticity of Ti-6Al-4V Alloy Processed by Equal Channel Angular Extrusion

    National Research Council Canada - National Science Library

    Shin, Dong H

    2006-01-01

    .... Specific tasks included: (1) Study superplastic deformation of a Ti-6Al-4V alloy that have been processed by equal channel angular extrusion and relate the deformation mechanism to the enhancement of superplasticity, and (2...

  12. In vitro and in vivo performance of bioactive Ti6Al4V/TiC/HA implants fabricated by a rapid microwave sintering technique.

    Science.gov (United States)

    Choy, Man Tik; Tang, Chak Yin; Chen, Ling; Wong, Chi Tak; Tsui, Chi Pong

    2014-09-01

    Failure of the bone-implant interface in a joint prosthesis is a main cause of implant loosening. The introduction of a bioactive substance, hydroxyapatite (HA), to a metallic bone-implant may enhance its fixation on human bone by encouraging direct bone bonding. Ti6Al4V/TiC/HA composites with a reproducible porous structure (porosity of 27% and pore size of 6-89 μm) were successfully fabricated by a rapid microwave sintering technique. This method allows the biocomposites to be fabricated in a short period of time under ambient conditions. Ti6Al4V/TiC/HA composites exhibited a compressive strength of 93 MPa, compressive modulus of 2.9 GPa and microhardness of 556 HV which are close to those of the human cortical bone. The in vitro preosteoblast MC3T3-E1 cells cultured on the Ti6Al4V/TiC/HA composite showed that the composite surface could provide a biocompatible environment for cell adhesion, proliferation and differentiation without any cytotoxic effects. This is among the first attempts to study the in vivo performance of load-bearing Ti6Al4V/TiC and Ti6Al4V/TiC/HA composites in a live rabbit. The results indicated that the Ti6Al4V/TiC/HA composite had a better bone-implant interface compared with the Ti6Al4V/TiC implant. Based on the microstructural features, the mechanical properties, and the in vitro and in vivo test results from this study, the Ti6Al4V/TiC/HA composites have the potential to be employed in load-bearing orthopedic applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Immobilisation of an antibacterial drug to Ti6Al4V components fabricated using selective laser melting

    Energy Technology Data Exchange (ETDEWEB)

    Vaithilingam, Jayasheelan [Additive Manufacturing and 3D Printing Research Group, School of Engineering, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Kilsby, Samuel [Department of Chemistry, Loughborough University, Loughborough LE11 3TU (United Kingdom); Goodridge, Ruth D., E-mail: Ruth.Goodridge@nottingham.ac.uk [Additive Manufacturing and 3D Printing Research Group, School of Engineering, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Christie, Steven D.R. [Department of Chemistry, Loughborough University, Loughborough LE11 3TU (United Kingdom); Edmondson, Steve [School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Hague, Richard J.M. [Additive Manufacturing and 3D Printing Research Group, School of Engineering, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2014-09-30

    Graphical abstract: The potential integration of selective laser melting (SLM) with surface modification using self-assembled monolayers for biomedical application has been investigated. Ciprofloxacin{sup ®} was functionalised to the SLM fabricated Ti6Al4V surface. Sustained release of the drug under in-vitro condition was witnessed. The inhibition zones showed the eluted drug was active against Staphylococcus aureus (a) and Escherichia coli (b) upon its release from the SLM fabricated part. - Highlights: • Parts fabricated using selective laser melting were coated with Ciprofloxacin{sup ®}. • The total amount of drug coated was approximately 1 μg/cm{sup 2}. • The coating was highly stable under oxidative conditions. • In-vitro studies showed a sustained release of the drug for over 42 days. • Ciprofloxacin{sup ®} eluted from the Ti6Al4V surface inhibited bacterial growth. - Abstract: Bacterial infections from biomedical implants and surgical devices are a major problem in orthopaedic, dental and vascular surgery. Although the sources of contaminations that lead to bacterial infections are known, it is not possible to control or avoid such infections completely. In this study, an approach to immobilise Ciprofloxacin{sup ®} (an antibacterial drug) to phosphonic acid based self-assembled monolayers (SAMs) adsorbed on a selectively laser melted (SLM) Ti6Al4V structure, has been presented. X-ray photoelectron spectroscopy (XPS) and static water contact angle measurements confirmed the attachment of SAMs and the drug. Results showed that Ciprofloxacin{sup ®} is highly stable under the oxidative conditions used in this study. In-vitro stability was estimated by immersing the Ciprofloxacin{sup ®} immobilised substrates in 10 mM of Tris–HCl buffer (pH-7.4) for 42 days. The Tris–HCl buffer was analysed using UV–vis spectrophotometry at 7, 14, 28 and 42 day time intervals to determine the release of the immobilised drug. The drug was observed to

  14. Immobilisation of an antibacterial drug to Ti6Al4V components fabricated using selective laser melting

    International Nuclear Information System (INIS)

    Vaithilingam, Jayasheelan; Kilsby, Samuel; Goodridge, Ruth D.; Christie, Steven D.R.; Edmondson, Steve; Hague, Richard J.M.

    2014-01-01

    Graphical abstract: The potential integration of selective laser melting (SLM) with surface modification using self-assembled monolayers for biomedical application has been investigated. Ciprofloxacin ® was functionalised to the SLM fabricated Ti6Al4V surface. Sustained release of the drug under in-vitro condition was witnessed. The inhibition zones showed the eluted drug was active against Staphylococcus aureus (a) and Escherichia coli (b) upon its release from the SLM fabricated part. - Highlights: • Parts fabricated using selective laser melting were coated with Ciprofloxacin ® . • The total amount of drug coated was approximately 1 μg/cm 2 . • The coating was highly stable under oxidative conditions. • In-vitro studies showed a sustained release of the drug for over 42 days. • Ciprofloxacin ® eluted from the Ti6Al4V surface inhibited bacterial growth. - Abstract: Bacterial infections from biomedical implants and surgical devices are a major problem in orthopaedic, dental and vascular surgery. Although the sources of contaminations that lead to bacterial infections are known, it is not possible to control or avoid such infections completely. In this study, an approach to immobilise Ciprofloxacin ® (an antibacterial drug) to phosphonic acid based self-assembled monolayers (SAMs) adsorbed on a selectively laser melted (SLM) Ti6Al4V structure, has been presented. X-ray photoelectron spectroscopy (XPS) and static water contact angle measurements confirmed the attachment of SAMs and the drug. Results showed that Ciprofloxacin ® is highly stable under the oxidative conditions used in this study. In-vitro stability was estimated by immersing the Ciprofloxacin ® immobilised substrates in 10 mM of Tris–HCl buffer (pH-7.4) for 42 days. The Tris–HCl buffer was analysed using UV–vis spectrophotometry at 7, 14, 28 and 42 day time intervals to determine the release of the immobilised drug. The drug was observed to release in a sustained manner. 50% of

  15. A synergistic effect of albumin and H₂O₂ accelerates corrosion of Ti6Al4V.

    Science.gov (United States)

    Yu, Fei; Addison, Owen; Davenport, Alison J

    2015-10-01

    The synergistic effect of albumin and H2O2 on corrosion of titanium alloy Ti6Al4V in physiological saline was investigated with long-term immersion tests and electrochemical methods. It was found that in the presence of both albumin and H2O2, the rate of metal release in immersion tests was far higher than in the presence of either species alone. Electrochemical polarisation curves and potentiostatic tests showed that H2O2 increased both the rates of the anodic and cathodic reactions, whilst albumin significantly decreased the rate of the cathodic reaction and slightly decreased the rate of the anodic reaction. The synergistic effect of albumin and H2O2 during immersion tests was attributed to the effect of adsorption of albumin in lowering the rate of the cathodic reaction and thus lowering the open circuit potential into the active region of titanium where complexation by H2O2 increased the corrosion rate. The corrosion attack was found to be greater in the β-phase of the alloy. The findings suggest that current standard tests in physiological or phosphate-buffered saline may underestimate the rate of corrosion in the peri-implant environment, in which albumin is the predominant protein, and reactive oxygen species such as H2O2 can occur as a result of inflammatory reactions in response to surgery, infection, or implant corrosion products. Corrosion of many biomedical implant materials occurs in the body leading to adverse biological responses. Several components of the environment into which a metal implant is placed including proteins and products of cellular physiology, been shown to modify corrosion resistance. Previously all studies on such components including the common protein albumin and the inflammatory product H2O2 have considered the effects of these species in isolation. For the first time we report a synergistic interaction between albumin and H2O2 significantly accelerating corrosion of Ti6Al4V at physiological pH and temperature. This is

  16. Microstructural influence on low-temperature superplasticity of ultrafine-grained Ti-6Al-4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Young Gun [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Kim, Woo Gyeom [Department of Metallurgy and Materials Science, Hanyang University, Ansan, Gyeonggi-Do 425-791 (Korea, Republic of); Lee, Chong Soo [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)]. E-mail: cslee@postech.ac.kr; Shin, Dong Hyuk [Department of Metallurgy and Materials Science, Hanyang University, Ansan, Gyeonggi-Do 425-791 (Korea, Republic of)

    2005-11-25

    Microstructural influence on low-temperature superplastic behavior of ultrafine-grained Ti-6Al-4V alloy fabricated by equal channel angular pressing (ECAP) was investigated. The deformed structures were analyzed with the increment of strain by transmission electron microscopy. Also, a series of tensile tests were carried out on ultrafine-grained (UFG) samples to measure elongation at temperature of 973 K and at strain rates of 10{sup -4} to 10{sup -2} s{sup -1}. The results indicated that elongation was significantly increased with increasing ECAP straining from 4 to 8 revealing more high-angle grain boundaries. Deformation mechanisms for UFG structure were analyzed in the context of inelastic deformation theory, which consisted of dislocation glide and grain boundary sliding.

  17. Interpretation of the Friction Coefficient During Reciprocating Sliding of Ti6Al4V Alloy Against Al2O3

    Directory of Open Access Journals (Sweden)

    S. Mitrovic

    2011-03-01

    Full Text Available Tribological behaviour of Ti6Al4V alloy, during linear reciprocating sliding against alumina, at nanotribometer (ball-on-flat type of contact was investigated. Experiments were carried out for sliding in Ringer's solution, over a range of loads (100 - 1000 mN and speeds (4 - 12 mm/s. Friction behaviour of the contact pairs was investigated by analysis of the dynamic friction coefficient plots and effective root mean square (rms coefficient of friction, COFrms. Presented mathematical envelopes of dynamic coefficient of friction curves and averaged envelope signals provided additional explanation of one calculated COFrms value. Envelopes of dynamic coefficient of friction enabled easier determination of different periods during sliding, which were further related to wear mechanisms.

  18. A study of electrode wear ratio on EDM of Ti-6AL-4V with copper-tungsten electrode

    Directory of Open Access Journals (Sweden)

    Zainal Nurezayana

    2016-01-01

    Full Text Available In this work, a study of electrode wear ratio (EWR on the diesinking electrical discharge machining (EDM of Ti-6AL-4V titanium alloy with copper-tungsten (Cu-W electrode has been carried out. Pulse on time (ON, pulse of time (OFF, peak current (V and servo voltage (SV were seen as the machining parameters. The experiments were run according to the design of experiments (DOE, which is two levels of full factorial with added centre points. The experimental results reveal that pulse on time and peak current are statistically significant parameters for affecting EWR with the p-value of 0.0013 and 0.0012 respectively. Moreover, based on ANOVA, we recognized peak current as the most significant parameters which contribute 31.75%, followed by pulse on time, servo voltage and pulse on time which contribute 30.99%, 8.68% and 0.72%, respectively.

  19. Influence of casting defects on fatigue strength of an investment cast Ti-6Al-4V alloy

    Directory of Open Access Journals (Sweden)

    Léopold Gaëlle

    2014-06-01

    Full Text Available The influence of casting defects on fatigue strength of an investment cast Ti-6Al-4V alloy is investigated. The most common of these defects are: pinhole, linear defect and inclusion. Each of them is currently defined by its size, morphology and position from the surface but is different from each other for a same type. An experimental campaign is defined with different types of defect. The first part of the campaign is focused on the influence of an artificial and spherical defect, considering two different surface conditions. It is shown that fatigue behaviour of this alloy is very sensitive to the surface condition of this artificial defect despite stress concentrations at the tip of the defect. The second part of the campaign is focused on casting defects: reduction of fatigue life is quantified and it is shown that an electro-discharge machined defect cannot be representative of pinhole.

  20. The effect of cryogenic cooling and minimum quantity lubrication on end milling of titanium alloy Ti-6Al-4V

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kyung Hee; Yang, Gi Dong; Lee, Dong Yoon; Kim, Tae Gon; Lee, Seok Woo [Korea Institute of Industrial Technology, Cheonan (Korea, Republic of); Suhaimi, M. A. [Universiti Teknologi Malaysia, Johor Bahru (Malaysia); Kim, Dong Won [Chonbuk National University, Jeonju (Korea, Republic of)

    2015-11-15

    The cooling down of cutting temperature in machining is very important for the improvement of tool life, especially when dealing with work materials that have low thermal conductivity such as titanium alloy. In this study designed to investigate the machining performance of a variety of cooling methods, cryogenic, Minimum quantity lubrication (MQL), and flood cooling are performed on solid end milling of titanium alloy, Ti-6Al-4V. In particular, the effect of internal and external spray methods on cryogenic machining is analyzed with a specially designed liquid nitrogen spraying system by evaluating tool wear and cutting force at cutting conditions. The cutting force is also analyzed for tool breakage detection. As a result, the combination of MQL and internal cryogenic cooling improves tool life by up to 32% compared to conventional cooling methods. The cutting force is also reduced significantly by this combination of cooling and lubrication strategy of side end milling.

  1. Dielectric and biochemical response of a PLA-PGA-HAp-Chitosan-Collagen coated on Ti6Al4V

    International Nuclear Information System (INIS)

    Montanez Superlano, Nerly Deyanira; Pena Ballesteros, Dario Yesid; Estupinan Duran, Hugo Armando

    2016-01-01

    The interaction of a polymeric biomaterial with a culture medium and osteoblast cells, electrodeposited on Ti6Al4V was evaluated. The compound is integrated of polylactic acid-polyglycolic acid-hydroxyapatite, modified with collagen and chitosan. The relative permittivity data embodied in a dielectric impedance spectrum identified the alpha and beta dispersions related to the ion exchange and the polarization of the cell membrane was calculated. Adhesion and cell proliferation was analyzed by epifluorescence microscopy, where it was observed on the third day of the cell culture process represented by mitosis core condensation and separation of the chromosomes. The surface morphology by SEM (Scanning Electron Microscope) and AFM (Atomic Force Microscope) biomaterial was observed and cellular activity was assessed by measuring alkaline phosphatase. Finally the best surface for adhesion and cell growth was found by statistical analysis, which corresponded to the coating with the highest concentration of chitosan and collagen

  2. Strain Rate and Stress Triaxiality Effects on Ductile Damage of Additive Manufactured TI-6AL-4V

    Science.gov (United States)

    Iannitti, Gianluca; Bonora, Nicola; Gentile, Domenico; Ruggiero, Andrew; Testa, Gabriel; Gubbioni, Simone

    2017-06-01

    In this work, the effects of strain rate and stress triaxiality on ductile damage of additive manufactured Ti-6Al-4V, also considering the build direction, were investigated. Raw material was manufactured by means of EOSSINT M2 80 machine, based on Direct Metal Laser Sintering technology, and machined to obtain round notched bar and Rod-on-Rod (RoR) specimens. Tensile tests on round notched bar specimens were performed in a wide range of strain rates. The failure strains at different stress triaxiality were used to calibrate the Bonora Damage Model. In order to design the RoR tests, numerical simulations were performed for assessing velocities at which incipient and fully developed damage occur. Tests at selected velocities were carried out and soft-recovered specimens were sectioning and polishing to observe the developed damage. Nucleated voids maps were compared with numerical simulations results.

  3. The effect of cryogenic cooling and minimum quantity lubrication on end milling of titanium alloy Ti-6Al-4V

    International Nuclear Information System (INIS)

    Park, Kyung Hee; Yang, Gi Dong; Lee, Dong Yoon; Kim, Tae Gon; Lee, Seok Woo; Suhaimi, M. A.; Kim, Dong Won

    2015-01-01

    The cooling down of cutting temperature in machining is very important for the improvement of tool life, especially when dealing with work materials that have low thermal conductivity such as titanium alloy. In this study designed to investigate the machining performance of a variety of cooling methods, cryogenic, Minimum quantity lubrication (MQL), and flood cooling are performed on solid end milling of titanium alloy, Ti-6Al-4V. In particular, the effect of internal and external spray methods on cryogenic machining is analyzed with a specially designed liquid nitrogen spraying system by evaluating tool wear and cutting force at cutting conditions. The cutting force is also analyzed for tool breakage detection. As a result, the combination of MQL and internal cryogenic cooling improves tool life by up to 32% compared to conventional cooling methods. The cutting force is also reduced significantly by this combination of cooling and lubrication strategy of side end milling.

  4. Metallurgical Behavior of Ti-6Al-4V Alloy Mini-Implants as a Temporary Anchorage Device in Orthodontics Applications

    Directory of Open Access Journals (Sweden)

    Mendoza-Bravo Ivan

    2014-01-01

    Full Text Available The application of mini implants as a temporary anchorage device in orthodontics is a new technique that allows the movement of teeth in an efficient and predictable way. Although they have started to be used in Germany, Japan and South Korea, there is still the need to analyze and diffuse the advantages this procedure can offer over the traditional techniques. The objective of this research work was to analyze the integrity of Ti-6Al-4V mini implants temporary employed for 4 months on three patients as an anchorage device. The mini implants were analyzed by means of electron scanning microscopy in order to determine superficial and microstructural changes as well as the interaction with human tissue. Results showed the presence of wear on the thread zone caused during the insertion into the maxilar bone. The adherence of organic tissue was also observed on two mini-implants.

  5. Effects of pressing temperature and initial microstructure on the equal channel angular pressing of Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Ko, Y.G.; Lee, Y.H.; Jung, W.S.; Shin, D.H.; Lee, C.S.

    2003-01-01

    The effects of pressing temperature and initial microstructure on the equal channel angular (ECA) pressing of Ti-6Al-4V alloy were investigated in this study. The ECA pressing was carried out isothermally with route C at 500 C, 600 C and 700 C for two typical microstructures, i.e., the Widmanstaetten microstructure and the equiaxed microstructure. The results showed that ECA pressing at 600 C and 700 C was successful without producing any noticeable segment at the specimen surfaces, while a large amount of surface segments were produced at 500 C. After 1 pass pressing at 600 C, the equiaxed microstructure showed more uniform material flow at the surface than the Widmanstaetten microstructure. However, this microstructural influence was diminished with increase of the number of the ECA pressing. A flow-localization parameter that quantifies the flow non-uniform tendency in case of flow softening materials was used to explain the different results in each microstructure. (orig.)

  6. Microstructure and erosive wear behaviors of Ti6Al4V alloy treated by plasma Ni alloying

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Z.X.; Wu, H.R.; Shan, X.L.; Lin, N.M.; He, Z.Y., E-mail: tyuthzy@126.com; Liu, X.P.

    2016-12-01

    Graphical abstract: The Ni modified layers were prepared on the surface of Ti6Al4V substrate by the plasma surface alloying technique. The surface and cross-section morphology, element concentration and phase composition were investigated by thermal field emission scanning electron microscopy (SEM), and glow discharge optical emission spectroscopy (GDOES), X-ray diffraction (XRD), respectively. The cross-section nano-scale hardness of Ni modified layer was measured by nano indenter. The results showed that Ni modified layers exhibited triple layers structure and continuous gradient distribution of the concentration. From the surface to the matrix, they were 2 μm Ni deposition layer, 8 μm Ni-rich alloying layer including the phases of Ni{sub 3}Ti, NiTi, Ti{sub 2}Ni, AlNi{sub 3} and 24 μm Ni-poor alloying layer forming the solid solution of nickel. With increasing of the thickness of Ni modified layer, the microhardness increased first, reached the climax, then gradient decreased. The erosion tests were performed on the surface of the untreated and treated Ti6Al4V sample using MSE (Micro-slurry-jet Erosion) method. The experiment results showed that the wear rate of every layer showed different value, and the Ni-rich alloying layer was the lowest. The strengthening mechanism of Ni modified layer was also discussed. - Highlights: • The Ni modified layers were prepared by the plasma surface alloying technique. • Triple layers structure was prepared. • Using Micro-slurry-jet Erosion method. • The erosion rate of Ni modified layer experienced the process of descending first and then ascending. • Improvement of erosion resistance performance of Ni-rich alloying layer was prominent. The wear mechanism of Ni modified layer showed micro-cutting wearing. - Abstract: The Ni modified layers were prepared on the surface of Ti6Al4V substrate by the plasma surface alloying technique. The surface and cross-section morphology, element concentration and phase composition

  7. Defect, Microstructure, and Mechanical Property of Ti-6Al-4V Alloy Fabricated by High-Power Selective Laser Melting

    Science.gov (United States)

    Cao, Sheng; Chen, Zhuoer; Lim, Chao Voon Samuel; Yang, Kun; Jia, Qingbo; Jarvis, Tom; Tomus, Dacian; Wu, Xinhua

    2017-12-01

    To improve the selective laser melting (SLM) productivity, a high laser power and accordingly adjusted parameters are employed to facilitate a high build rate. Three distinct processing strategies with incremental build rate are developed for SLM Ti-6Al-4V. Various types of defects are investigated. Further studies were carried out by heat-treatment and hot isostatic pressing to evaluate the influence of microstructure and porosity on mechanical properties. The anisotropic mechanical property in horizontally and vertically build samples were observed, which was attributable to the columnar grains and spatial arrangement of defects. Regardless of anisotropy, a post-SLM heat-treatment at 800°C for 2 h produces a combined high strength and ductility.

  8. Experimental analysis on semi-finishing machining of Ti6Al4V additively manufactured by direct melting laser sintering

    Science.gov (United States)

    Imbrogno, Stano; Bordin, Alberto; Bruschi, Stefania; Umbrello, Domenico

    2016-10-01

    The Additive Manufacturing (AM) techniques are particularly appealing especially for titanium aerospace and biomedical components because they permit to achieve a strong reduction of the buy-to-fly ratio. However, finishing machining operations are often necessary to reduce the uneven surface roughness and geometrics because of local missing accuracy. This work shows the influence of the cutting parameters, cutting speed and feed rate, on the cutting forces as well as on the thermal field observed in the cutting zone, during a turning operation carried out on bars made of Ti6Al4V obtained by the AM process called Direct Metal Laser Sintering (DMLS). Moreover, the sub-surface microstructure alterations due to the process are also showed and commented.

  9. Analysis Of Deformation And Microstructural Evolution In The Hot Forging Of The Ti-6Al-4V Alloy

    Directory of Open Access Journals (Sweden)

    Kukuryk M.

    2015-06-01

    Full Text Available The paper presents the analysis of the three-dimensional strain state for the cogging process of the Ti-6Al-4V alloy using the finite element method, assuming the rigid-plastic model of the deformed body. It reports the results of simulation studies on the metal flow pattern and thermal phenomena occurring in the hot cogging process conducted on three tool types. The computation results enable the determination of the distribution of effective strain, effective stress, mean stress and temperature within the volume of the blank. This solution has been complemented by adding the model of microstructure evolution during the cogging process. The numerical analysis was made using the DEFORM-3D consisting of a mechanical, a thermal and a microstructural parts. The comparison of the theoretical study and experimental test results indicates a potential for the developed model to be employed for predicting deformations and microstructure parameters.

  10. Creep study of mechanisms involved in low-temperature superplasticity of UFG Ti-6Al-4V processed by SPD

    Energy Technology Data Exchange (ETDEWEB)

    Kral, Petr, E-mail: pkral@ipm.cz [Institute of Physics of Materials, ASCR, Zizkova 22, CZ -61662 Brno (Czech Republic); CEITEC – IPM ASCR, v.v.i., Zizkova 22, CZ-61662 Brno (Czech Republic); Dvorak, Jiri [Institute of Physics of Materials, ASCR, Zizkova 22, CZ -61662 Brno (Czech Republic); CEITEC – IPM ASCR, v.v.i., Zizkova 22, CZ-61662 Brno (Czech Republic); Blum, Wolfgang [Inst. f. Werkstoffwissenschaften, University of Erlangen-Nürnberg, D-91058 Erlangen (Germany); Kudryavtsev, Egor; Zherebtsov, Sergey; Salishchev, Gennady [Belgorod State University, Laboratory of Bulk Nanostructured Materials, Pobeda Str. 85, 308015 Belgorod (Russian Federation); Kvapilova, Marie; Sklenicka, Vaclav [Institute of Physics of Materials, ASCR, Zizkova 22, CZ -61662 Brno (Czech Republic); CEITEC – IPM ASCR, v.v.i., Zizkova 22, CZ-61662 Brno (Czech Republic)

    2016-06-15

    The deformation kinetics of ultrafine-grained Ti-6Al-4V with mean (sub)grain size about 150 nm (produced by isothermal multiaxial forging) and superplastic properties at the relatively low temperature of 873 K was investigated in compression and tension over a large range of strain rates from 10{sup −7} to 10{sup −2} s{sup −1}. Electron microscopic observations showed that the grains coarsen during deformation towards the quasi-stationary spacing w{sub qs} of strain induced boundaries. In spite of the grain coarsening the grains were generally smaller than w{sub qs} allowing high-angle boundaries to dominate the quasi-stationary strength. Texture measurements indicate that dislocation glide plays a large role in deformation. Glide in this alloy is significantly influenced by solid solution strengthening leading to a stress sensitivity of strain rate of n = 3. The present ultrafine-grained Ti alloy displays a stress sensitivity exponent n = 2 over an extended stress range where its superplastic behavior is optimal. While the deformation kinetics of present ultrafine-grained Ti alloy can be roughly explained by the traditional formula for superplastic flow, the significant discrepancy to the measured values suggests that solid solution strengthening must be taken into account to get a complete insight. - Highlights: • The UFG Ti-6Al-4V alloy behaves superplastically at low temperature of 873 K. • Grain coarsening at low stresses limits superplasticity of UFG Ti alloy. • Solute strengthening plays an important role in low-temperature superplasticity. • Acceleration of creep in UFG Ti alloy is caused by processes related to hab.

  11. Creep study of mechanisms involved in low-temperature superplasticity of UFG Ti-6Al-4V processed by SPD

    International Nuclear Information System (INIS)

    Kral, Petr; Dvorak, Jiri; Blum, Wolfgang; Kudryavtsev, Egor; Zherebtsov, Sergey; Salishchev, Gennady; Kvapilova, Marie; Sklenicka, Vaclav

    2016-01-01

    The deformation kinetics of ultrafine-grained Ti-6Al-4V with mean (sub)grain size about 150 nm (produced by isothermal multiaxial forging) and superplastic properties at the relatively low temperature of 873 K was investigated in compression and tension over a large range of strain rates from 10 −7 to 10 −2 s −1 . Electron microscopic observations showed that the grains coarsen during deformation towards the quasi-stationary spacing w qs of strain induced boundaries. In spite of the grain coarsening the grains were generally smaller than w qs allowing high-angle boundaries to dominate the quasi-stationary strength. Texture measurements indicate that dislocation glide plays a large role in deformation. Glide in this alloy is significantly influenced by solid solution strengthening leading to a stress sensitivity of strain rate of n = 3. The present ultrafine-grained Ti alloy displays a stress sensitivity exponent n = 2 over an extended stress range where its superplastic behavior is optimal. While the deformation kinetics of present ultrafine-grained Ti alloy can be roughly explained by the traditional formula for superplastic flow, the significant discrepancy to the measured values suggests that solid solution strengthening must be taken into account to get a complete insight. - Highlights: • The UFG Ti-6Al-4V alloy behaves superplastically at low temperature of 873 K. • Grain coarsening at low stresses limits superplasticity of UFG Ti alloy. • Solute strengthening plays an important role in low-temperature superplasticity. • Acceleration of creep in UFG Ti alloy is caused by processes related to hab.

  12. Surface properties of Ti-6Al-4V alloy part I: Surface roughness and apparent surface free energy.

    Science.gov (United States)

    Yan, Yingdi; Chibowski, Emil; Szcześ, Aleksandra

    2017-01-01

    Titanium (Ti) and its alloys are the most often used implants material in dental treatment and orthopedics. Topography and wettability of its surface play important role in film formation, protein adhesion, following osseointegration and even duration of inserted implant. In this paper, we prepared Ti-6Al-4V alloy samples using different smoothing and polishing materials as well the air plasma treatment, on which contact angles of water, formamide and diiodomethane were measured. Then the apparent surface free energy was calculated using four different approaches (CAH, LWAB, O-W and Neumann's Equation of State). From LWAB approach the components of surface free energy were obtained, which shed more light on the wetting properties of samples surface. The surface roughness of the prepared samples was investigated with the help of optical profilometer and AFM. It was interesting whether the surface roughness affects the apparent surface free energy. It was found that both polar interactions the electron donor parameter of the energy and the work of water adhesion increased with decreasing roughness of the surfaces. Moreover, short time plasma treatment (1min) caused decrease in the surface hydrophilic character, while longer time (10min) treatment caused significant increase in the polar interactions and the work of water adhesion. Although Ti-6Al-4V alloy has been investigated many times, to our knowledge, so far no paper has been published in which surface roughness and changes in the surface free energy of the alloy were compared in the quantitative way in such large extent. This novel approach deliver better knowledge about the surface properties of differently smoothed and polished samples which may be helpful to facilitate cell adhesion, proliferation and mineralization. Therefore the results obtained present also potentially practical meaning. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Electrochemical behavior of 45S5 bioactive ceramic coating on Ti6Al4V alloy for dental applications

    Science.gov (United States)

    Machado López, M. M.; Espitia Cabrera, M. I.; Faure, J.; Contreras García, M. E.

    2016-04-01

    Titanium and its alloys are widely used as implant materials because of their mechanical properties and non-toxic behavior. Unfortunately, they are not bioinert, which means that they can release ions and can only fix the bone by mechanical anchorage, this can lead to the encapsulation of dense fibrous tissue in the body. The bone fixation is required in clinical conditions treated by orthopedic and dental medicine. The proposal is to coat metallic implants with bioactive materials to establish good interfacial bonds between the metal substrate and bone by increasing bioactivity. Bioactive glasses, ceramics specifically 45 S5 Bioglass, have drawn attention as a serious functional biomaterial because osseointegration capacity. The EPD method of bioglass gel precursor was proposed in the present work as a new method to obtain 45S5/Ti6A14V for dental applications. The coatings, were thermally treated at 700 and 800°C and presented the 45 S5 bioglass characteristic phases showing morphology and uniformity with no defects, quantification percentages by EDS of Si, Ca, Na, P and O elements in the coating scratched powders, showed a good proportional relationship demonstrating the obtention of the 45S5 bioglass. The corrosion tests were carried out in Hank's solution. By Tafel extrapolation, Ti6Al4V alloy showed good corrosion resistance in Hank's solution media, by the formation of a passivation layer on the metal surface, however, in the system 45S5/Ti6Al4V there was an increase in the corrosion resistance; icon-, Ecorr and corrosion rate decreased, the mass loss and the rate of release of ions, were lower in this system than in the titanium alloy without coating.

  14. The microstructure and surface hardness of Ti6Al4V alloy implanted with nitrogen ions at an elevated temperature

    Energy Technology Data Exchange (ETDEWEB)

    Vlcak, Petr, E-mail: petr.vlcak@fs.cvut.cz [Department of Physics, Faculty of Mechanical Engineering, Czech Technical University in Prague, Technicka 4, 16607 Prague (Czech Republic); Cerny, Frantisek [Department of Physics, Faculty of Mechanical Engineering, Czech Technical University in Prague, Technicka 4, 16607 Prague (Czech Republic); Drahokoupil, Jan [Department of Metals, Institute of Physics, AS CR, v.v.i., Na Slovance 2, 182 21 Prague (Czech Republic); Sepitka, Josef [Department of Mechanics, Biomechanics and Mechatronics, Faculty of Mechanical Engineering, Czech Technical University in Prague, Technicka 4, 16607 Prague (Czech Republic); Tolde, Zdenek [Department of Materials Engineering, Faculty of Mechanical Engineering, Czech Technical University in Prague, Technicka 4, 16607 Prague (Czech Republic)

    2015-01-25

    Highlights: • The Ti6Al4V samples were implanted with 90 keV nitrogen ions. • The samples were annealed at 500 °C during the ion implantation process. • An elevated temperature increases the mobility of the atoms and the quantity of TiN. • The hardness showed a significant increase compared to room temperature implantation. - Abstract: The effect of an elevated temperature during nitrogen ion implantation on the microstructure and on the surface hardness of Ti6Al4V titanium alloy was examined. The implantation process was carried out at fluences of 1 ⋅ 10{sup 17}, 2.7 ⋅ 10{sup 17} and 6 ⋅ 10{sup 17} cm{sup −2} and at ion energy 90 keV. The implanted samples were annealed at 500 °C during the implantation process. X-ray diffraction analysis was performed to obtain a phase characterization and a phase quantification in the implanted sample surface. The surface hardness was investigated by nanoindentation testing, and the nitrogen depth distribution was measured by Rutherford Backscattering Spectroscopy. Elevated temperature led to increased formation of a TiN compound. It was found that a mixture of TiN and an α-Ti(+N) solid solution had a predominant amount of TiN for samples with fluence of 2.7 ⋅ 10{sup 17} cm{sup −2} or higher. Elevated temperature during ion implantation caused an increase in surface hardening more towards the depth of the substrate in comparison with room temperature implantation. The hardness showed a remarkably significant increase at a fluence of 1 ⋅ 10{sup 17} and 2.7 ⋅ 10{sup 17} cm{sup −2} compared to samples implanted at the same fluences and at room temperature. There is a discussion of such mechanisms that explain the observed hardening more towards the depth of the substrate, and the increase in hardness.

  15. High Temperature Dynamic Response of a Ti-6Al-4V Alloy: A Modified Constitutive Model for Gradual Phase Transformation

    Science.gov (United States)

    Gangireddy, S.; Mates, S. P.

    2017-12-01

    Dynamic deformation behavior of a commercial Ti-6Al-4V alloy is measured between room temperature and beyond the β-transus temperature with high thermal resolution using a rapid-heating Kolsky bar technique. The high thermal resolution allows for a thorough investigation of the dynamic thermal softening behavior of this alloy including effects related to the transformation from the initial hcp α/bcc β dual phase structure to a full β structure for improved modeling of high temperature dynamic manufacturing processes such as high-speed machining. Data are obtained at an average strain rate of 1800 s-1 from room temperature to 1177 °C, with total heating times limited to 3.5 s for all tests. Short heating times prevent thermal distortion of the Kolsky bar loading waves and can allow an investigation of non-equilibrium mechanical behavior, although no such behavior was identified in this study. Between 800 °C and 1000 °C, a progressive change in the thermal softening rate was observed that corresponded well with the equilibrium phase diagram for this alloy. The dynamic thermal softening behavior in the transformation region is incorporated via a new modification of the Johnson-Cook (J-C) viscoplastic constitutive equation. Rate sensitivity is determined at room temperature by combining Kolsky bar data with quasi-static measurements at strain rates from 7.5 × 10-5 s-1 to 0.16 s-1 and the data are fit using multi-parameter optimization to arrive at a full modified J-C model for Ti-6Al-4V to nearly 1200 °C. In its generic form, the modification factor we propose, G( T), is applicable to any material system undergoing gradual phase transformation over a range of temperatures.

  16. Structural characterization and electrochemical behavior of 45S5 bioglass coating on Ti6Al4V alloy for dental applications

    Energy Technology Data Exchange (ETDEWEB)

    López, M.M. Machado, E-mail: machadolopez23@gmail.com [Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, C.U. Edificio “U”, C.P. 58000, Morelia, Michoacán, México (Mexico); Fauré, J. [Laboratoire Ingénierie et Sciences des Matériaux (LISM EA 4695) - Université de Reims Champagne-Ardenne, 21 rue Clément Ader, Reims, BP 138 Cedex 02, 51685 France (France); Cabrera, M.I. Espitia [Facultad de ingeniería Química, Universidad Michoacana de San Nicolás de Hidalgo, C.U. Edificio “D”, C.P. 58000, Morelia, Michoacán, México (Mexico); García, M.E. Contreras, E-mail: eucontre@umich.mx [Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, C.U. Edificio “U”, C.P. 58000, Morelia, Michoacán, México (Mexico)

    2016-04-15

    Graphical abstract: - Highlights: • Bioglass 45S5 nanostructured films were obtained by colloidal electrophoretic deposition (CEDP) method, proposed in this work, on Ti6Al4 V substrates. • Ti6Al4 V corrosion resistance in Hank's solution was increased with bioglass 45S5 coating. • Crystalline phases of 45S5 bioglass xerogels were obtained and characterized by XRD. • The model of chemical anchoring between Ti6Al4 V and bioglass 45S5 is proposed. - Abstract: In the present work, 45S5 bioglass coatings were deposited on the Ti6Al4 V alloy substrate through the cathodic colloidal electrophoretic deposition process (CEDP) proposed in this work. The coatings were thermally treated at temperatures of 500, 600, 700, and 800 °C for 2 h, and their structure was characterized by FESEM and DRX. Nanostructure and phase evolution of the coatings and xerogels was followed as a function of temperature. The corrosion resistance of the Ti6Al4 V alloy and the 45S5/Ti6Al4 V coating was studied by means of Tafel extrapolation in Hank's solution, at 37 °C, simulating the conditions inside the mouth. The 45S5 bioglass coatings displayed an amorphous nanostructure at lower temperatures, and partial crystallization at higher temperatures. An increase in the corrosion resistance was observed in the 45S5/Ti6l4 V coating treated at 700 °C because it reduced the i{sub corr}, and there was a change in the E{sub corr} towards more noble values. A model of the chemical anchorage of the 45S5 bioglass coating on Ti6Al4 V was proposed.

  17. Grinding behavior and surface appearance of (TiCp + TiBw/Ti-6Al-4V titanium matrix composites

    Directory of Open Access Journals (Sweden)

    Ding Wenfeng

    2014-10-01

    Full Text Available (TiCp + TiBw/Ti-6Al-4V titanium matrix composites (PTMCs have broad application prospects in the aviation and nuclear field. However, it is a typical difficult-to-cut material due to high hardness of the reinforcements, high strength and low thermal conductivity of Ti-6Al-4V alloy matrix. Grinding experiments with vitrified CBN wheels were conducted to analyze comparatively the grinding performance of PTMCs and Ti-6Al-4V alloy. Grinding force and force ratios, specific grinding energy, grinding temperature, surface roughness, ground surface appearance were discussed. The results show that the normal grinding force and the force ratios of PTMCs are much larger than that of Ti-6Al-4V alloy. Low depth of cut and high workpiece speed are generally beneficial to achieve the precision ground surface for PTMCs. The hard reinforcements of PTMCs are mainly removed in the ductile mode during grinding. However, the removal phenomenon of the reinforcements due to brittle fracture still exists, which contributes to the lower specific grinding energy and grinding temperature of PTMCs than Ti-6Al-4V alloy.

  18. Characterisation of Ti-6Al-4V/glass-ceramic and pre-oxidised Kovar/glass-ceramic interfaces

    Science.gov (United States)

    Yates, Paul

    Glass-to-metal seals are used in a wide range of components. The nature of the interfaces between the constituents is often crucial to the performance of the seal and thus the aim of this study was to characterise the various interfaces in a novel seal made from a strontium boroaluminate glass-ceramic and the alloys Ti-6Al-4V and Kovar (Fe-29Ni-17Co). A titanium boride was found, by STEM, EELS and WDX, to have formed at the glass-ceramic to Ti-6Al-4V interface and to be bonded to both the metal on one side and the glass-ceramic on the other, in contrast to the classic view of glass to metal interfaces where bonding is thought to be promoted through metal dissolving into the glass / glass-ceramic. To establish bonding at the other interface, it was necessary to grow an oxide layer on the Kovar, by heating in air at 700 °C or 800 °C for 10 minutes. The oxide grown at both temperatures was shown (by XPS, XRD, SEM, EDX, STEM and Raman) to have the same composition, with the only significant difference being thickness (2.1 +/- 0.6) µm and (4.0 +/- 0.2) µm thick, for the oxides grown at 700 °C and 800 °C respectively. However, the oxide was found to be much more complex than was indicated by prior literature, comprising four layers. The top layer of the oxide was (Fe,Co)_3O_4, with an Fe_2O_3 layer beneath it. Below these layers were a further two layers of (Fe,Co,Ni)_3O_4. When heated to 800 °C, to simulate the sealing conditions, the oxide was changed to an Fe_3O_4 layer with metallic cobalt and nickel inclusions. Bonding was shown, by SEM and STEM, to occur between the oxidised Kovar and the glass-ceramic, as a result of dissolution of iron from the oxide into the glass. Although the interfaces were not definitively optimised, the seals produced were satisfactory and hermetic.

  19. Microscopic, crystallographic and adherence properties of plasma-sprayed calcium phosphate coatings on Ti-6Al-4V

    Science.gov (United States)

    Tufekci, Eser

    Recently, plasma-spayed titanium implants have become very popular in the dentistry because of their biocompatibility and ability of providing osseointegration with the surrounding bone. Although there are numerous published studies on these materials, information and standards are still lacking. This study investigated the miscrostructural, crystallographic and adherence properties of plasma-sprayed hydroxyapatite coatings on Ti-6Al-4V substrates. The microstructures of the coatings and the elemental interdiffusion near the coating/substrate interface were investigated using a scanning electron microscope (SEM) equipped with x-ray energy-dispersive spectroscopy (EDS). X-ray diffraction analyses performed on Ti-6Al-4V coupons prepared with different percent crystallinities have provided structural information such as degree of crystallinity, phases present, average crystallite size, as well as the residual stresses within the coating. For evaluation of the adherence of the coatings to the substrates, experimental rods were subjected to torsion. The fracture surfaces were analyzed using SEM/EDS to develop a new methodology to determine the percent adherence of the coatings. SEM studies indicated that the surface microstructures of commercial dental implants were consistent with the plasma-spraying. In cross-section, coatings exhibited minimal porosity and limited interdiffusion of titanium and calcium at the coating/substrate interface. X-ray diffraction analyses indicated that the highest crystallinity coatings consisted of almost entirely HA and an amorphous calcium phosphate phase. As the coating crystallinity decreased, increasing amounts of alpha- and beta-tricalcium phosphate and tetracalcium phosphate were detected. The mean percent crystallinity for the three sets of coatings ranged from 50-60%. The mean HA crystallite size for the three sets of coatings ranged from about 0.02-0.04 mum. Differences in mean interplanar spacings for three selected

  20. Surface Texture-Based Surface Treatments on Ti6Al4V Titanium Alloys for Tribological and Biological Applications: A Mini Review

    Directory of Open Access Journals (Sweden)

    Naiming Lin

    2018-03-01

    Full Text Available Surface texture (ST has been confirmed as an effective and economical surface treatment technique that can be applied to a great range of materials and presents growing interests in various engineering fields. Ti6Al4V which is the most frequently and successfully used titanium alloy has long been restricted in tribological-related operations due to the shortcomings of low surface hardness, high friction coefficient, and poor abrasive wear resistance. Ti6Al4V has benefited from surface texture-based surface treatments over the last decade. This review begins with a brief introduction, analysis approaches, and processing methods of surface texture. The specific applications of the surface texture-based surface treatments for improving surface performance of Ti6Al4V are thoroughly reviewed from the point of view of tribology and biology.

  1. Production of hard hydrophilic Ni-B coatings on hydrophobic Ni-Ti and Ti-6Al-4V alloys by electroless deposition

    Energy Technology Data Exchange (ETDEWEB)

    Buelbuel, Ferhat; Karabudak, Filiz; Yesildal, Ruhi [Ataturk Univ., Erzurum (Turkey). Mechanical Engineering Dept.

    2017-07-01

    This paper is mainly focused on the wetting state of liquid droplets on Ni-Ti and Ti-6Al-4V hierarchical structured hydrophobic surfaces in micro/nanoscale. Electroless Ni-B deposition as a surface coating treatment has recently drawn considerable attention of researchers owing to remarkable advantages when compared with other techniques such as low price, conformal ability to coat substrates, good bath stability and relatively easier plating process control. The Ni-Ti and Ti-6Al-4V substrates were plated by electroless Ni-B plating process. The coated films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), hardness testing and static contact angle measurement. Results obtained from the analyses show that electroless Ni-B deposition may improve the hardness and wettability of the Ni-Ti and Ti-6Al-4V alloy surfaces.

  2. Surface Texture-Based Surface Treatments on Ti6Al4V Titanium Alloys for Tribological and Biological Applications: A Mini Review.

    Science.gov (United States)

    Lin, Naiming; Li, Dali; Zou, Jiaojuan; Xie, Ruizhen; Wang, Zhihua; Tang, Bin

    2018-03-24

    Surface texture (ST) has been confirmed as an effective and economical surface treatment technique that can be applied to a great range of materials and presents growing interests in various engineering fields. Ti6Al4V which is the most frequently and successfully used titanium alloy has long been restricted in tribological-related operations due to the shortcomings of low surface hardness, high friction coefficient, and poor abrasive wear resistance. Ti6Al4V has benefited from surface texture-based surface treatments over the last decade. This review begins with a brief introduction, analysis approaches, and processing methods of surface texture. The specific applications of the surface texture-based surface treatments for improving surface performance of Ti6Al4V are thoroughly reviewed from the point of view of tribology and biology.

  3. Microstructure and Mechanical Properties of Ti-6Al-4V Fabricated by Selective Laser Melting of Powder Produced by Granulation-Sintering-Deoxygenation Method

    Science.gov (United States)

    Sun, Pei; Fang, Z. Zak; Zhang, Ying; Xia, Yang

    2017-12-01

    Commercial spherical Ti powders for additive manufacturing applications are produced today by melt-atomization methods at relatively high costs. A meltless production method, called granulation-sintering-deoxygenation (GSD), was developed recently to produce spherical Ti alloy powder at a significantly reduced cost. In this new process, fine hydrogenated Ti particles are agglomerated to form spherical granules, which are then sintered to dense spherical particles. After sintering, the solid fully dense spherical Ti alloy particles are deoxygenated using novel low-temperature deoxygenation processes with either Mg or Ca. This technical communication presents results of 3D printing using GSD powder and the selective laser melting (SLM) technique. The results showed that tensile properties of parts fabricated from spherical GSD Ti-6Al-4V powder by SLM are comparable with typical mill-annealed Ti-6Al-4V. The characteristics of 3D printed Ti-6Al-4V from GSD powder are also compared with that of commercial materials.

  4. Effects of Dextrose and Lipopolysaccharide on the Corrosion Behavior of a Ti-6Al-4V Alloy with a Smooth Surface or Treated with Double-Acid-Etching

    Science.gov (United States)

    Faverani, Leonardo P.; Assunção, Wirley G.; de Carvalho, Paulo Sérgio P.; Yuan, Judy Chia-Chun; Sukotjo, Cortino; Mathew, Mathew T.; Barao, Valentim A.

    2014-01-01

    Diabetes and infections are associated with a high risk of implant failure. However, the effects of such conditions on the electrochemical stability of titanium materials remain unclear. This study evaluated the corrosion behavior of a Ti-6Al-4V alloy, with a smooth surface or conditioned by double-acid-etching, in simulated body fluid with different concentrations of dextrose and lipopolysaccharide. For the electrochemical assay, the open-circuit-potential, electrochemical impedance spectroscopy, and potentiodynamic test were used. The disc surfaces were characterized by scanning electron microscopy and atomic force microscopy. Their surface roughness and Vickers microhardness were also tested. The quantitative data were analyzed by Pearson's correlation and independent t-tests (α = 0.05). In the corrosion parameters, there was a strong lipopolysaccharide correlation with the Ipass (passivation current density), Cdl (double-layer capacitance), and Rp (polarization resistance) values (pTi-6Al-4V alloy with surface treatment by double-acid-etching. The combination of dextrose and lipopolysaccharide was correlated with the Icorr (corrosion current density) and Ipass (pTi-6Al-4V alloy decreased (pTi-6Al-4V alloy increased (pTi-6Al-4V alloy by increasing the surface thickness mainly in the group associated with dextrose and lipopolysaccharide. The combination of dextrose and lipopolysaccharide affected the corrosion behavior of the Ti-6Al-4V alloy surface treated with double-acid-etching. However, no dose-response corrosion behavior could be observed. These results suggest a greater susceptibility to corrosion of titanium implants in diabetic patients with associated infections. PMID:24671257

  5. Design and biological functionality of a novel hybrid Ti-6Al-4V/hydrogel system for reconstruction of bone defects.

    Science.gov (United States)

    Kumar, Alok; Nune, K C; Misra, R D K

    2018-04-01

    We have designed a unique injectable bioactive hydrogel comprising of alginate, gelatin, and nanocrystalline hydroxyapatite and loaded with osteoblasts, with the ability to infiltrate into three-dimensional Ti-6Al-4V scaffolds with interconnected porous architecture, fabricated by electron beam melting. A two-step crosslinking process using the EDC/NHS and CaCl 2 was adopted and found to be effective in the fabrication of cell-loaded hydrogel/Ti-6Al-4V scaffold system. This hybrid Ti-6Al-4V scaffold/hydrogel system was designed for the reconstruction of bone defects, which are difficult to heal in the absence of suitable support materials. The hybrid Ti-6Al-4V/hydrogel system favourably modulated the biological functions, namely, adhesion, proliferation, cell-to-cell, and cell-material communication because of the presence of extracellular matrix-like hydrogel in the interconnected porous structure of 3D printed Ti-6Al-4V scaffold. The hydrogel was cytocompatible, which was proven through live/dead assay, the expression level of prominent proteins for cell adhesion and cytoskeleton, including 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay. Furthermore, the high bone formation ability of the hydrogel was confirmed using alkaline phosphatase assay. A high equilibrium water content (~97%) in the hydrogel enables the delivery of cells and bioactive molecules, necessary for bone tissue growth. Although not studied, the presence of hydrogel in the pores of the scaffold can provide the space for the cell migration as well as vascularization through it, required for the effective exchange of nutrients. In conclusion, we underscore that the 3D-printed Ti-6Al-4V scaffold-loaded with bioactive hydrogel to treat the bone defects significantly impacted cellular functions and cell-material interaction. Copyright © 2017 John Wiley & Sons, Ltd.

  6. Corrosion resistance characteristics of a Ti-6Al-4V alloy scaffold that is fabricated by electron beam melting and selective laser melting for implantation in vivo

    International Nuclear Information System (INIS)

    Zhao, Bingjing; Wang, Hong; Qiao, Ning; Wang, Chao; Hu, Min

    2017-01-01

    The purpose of this study is to determine the corrosion resistance of Ti-6Al-4V alloy fabricated with electron beam melting and selective laser melting for implantation in vivo. Ti-6Al-4V alloy specimens were fabricated with electron beam melting (EBM) and selective laser melting (SLM). A wrought form of Ti-6Al-4V alloy was used as a control. Surface morphology observation, component analysis, corrosion resistance experimental results, electrochemical impedance spectroscopy, crevice corrosion resistance experimental results, immersion test and metal ions precipitation analysis were processed, respectively. The thermal stability of EBM specimen was the worst, based on the result of open circuit potential (OCP) result. The result of electrochemical impedance spectroscopy indicated that the corrosion resistance of the SLM specimen was the best under the low electric potential. The result of potentiodynamic polarization suggested that the corrosion resistance of the SLM specimen was the best under the low electric potential (< 1.5 V) and EBM specimen was the best under the high electric potential (> 1.5 V).The crevice corrosion resistance of the EBM specimen was the best. The corrosion resistance of SLM specimen was the best, based on the result of immersion test. The content of Ti, Al and V ions of EBM, SLM and wrought specimens was very low. In general, the scaffolds that were fabricated with EBM and SLM had good corrosion resistance, and were suitable for implantation in vivo. - Highlights: • EBM and SLM Ti-6Al-4V alloy have good corrosion resistance, and both of them can be applied in vivo. • SLM Ti-6Al-4V alloy was more suitable for implantation in vivo than that of EBM Ti-6Al-4V alloy. • The crevice corrosion resistance of the EBM specimen is the best. • EBM and SLM specimens can form oxide film.

  7. Effect of heat treatment on microstructures and mechanical properties of a Ti-6Al-4V alloy rod prepared by powder compact extrusion

    Science.gov (United States)

    Yang, Fei; Gabbitas, Brian

    2015-03-01

    In this paper, Ti-6Al-4V alloy rods were manufactured by the powder compact extrusion of a powder mixture of hydride-dehydride (HDH) titanium powder, elemental aluminum powder and master alloy powder. Extrusions were carried out at 1300°C and with a holding time of 5 min in an argon atmosphere. The effects of different heat treatments (HT1: 960°C/1 h, water quenching, HT2: 960°C/1 h, water quenching + 500°C/6 h, air cooling, HT3: 850°C/2 h, furnace cooling to 540°C, then air cooling) on the microstructure and mechanical properties of as-extruded Ti-6Al-4V alloy rods were investigated. The results showed that a homogeneous microstructure, composed of a lamellar structure with a grain size range of 40-60 μm, was produced by powder compact extrusion of a powder mixture. The mechanical properties achieved were an ultimate tensile strength (UTS) of 1254 MPa, a yield strength (YS) of 1216 MPa and 8% ductility. After quenching at 960°C and with a holding time of 1 h, the UTS and YS of the heat treated Ti-6Al-4V alloy rod were increased to 1324 MPa and 1290 MPa, and the ductility was increased to 12%. After HT2, the UTS and YS of the heat treated Ti-6Al-4V alloy rod were significantly increased to 1436 MPa and 1400 MPa, but the ductility decreased to 4%. After HT3, the mechanical properties of the heat treated Ti-6Al-4V alloy rod were slightly decreased to give a UTS of 1213 MPa and a YS of 1180 MPa, with an increase in ductility to 11%. The microstructural changes of as-extruded Ti-6Al-4V alloy rods were also investigated for the different heat treatments.

  8. Fatigue crack propagation behavior and debris formation in Ti-6Al-4V alloys with different grain size

    Science.gov (United States)

    Kim, H. J.; Nakahigashi, J.; Ebara, R.; Endo, M.

    2017-05-01

    Titanium alloy is widely used in applications where high specific strength as well as good heat and corrosion resistance is required. Consequently, there are a number of studies on the fatigue characteristics of titanium alloys. In recent years, grain refinement for metallic materials processed by several methods, such as severe plastic deformation, has been studied to improve the mechanical properties. Grain refinement of titanium alloy by the protium treatment is a new technology, and the fatigue properties of this material have yet to be sufficiently studied. Therefore in this study, tension-compression fatigue tests were conducted for a protium treated Ti-6Al-4V alloy with ultra-fine grains of 0.5 μm in average size as well as for an untreated alloy with conventional grains of 6 μm. Specimens had shallow, sharp notches with the depth of 50 μm and the root radius of 10 μm, which enabled successive observation of the initiation and early propagation behaviors of small fatigue cracks. Substantial amount of oxide debris was formed along the crack during crack propagation. The role of debris was discussed in association with propagation resistance.

  9. Fatigue and creep-fatigue damage assessment in Ti-6AL-4V titanium alloy using IR-thermography

    International Nuclear Information System (INIS)

    Kumar, Jalaj; Kumar, Vikas; Sundara Raman, S. Ganesh

    2015-01-01

    Titanium alloys such as Ti-6Al-4V are susceptible for fatigue and creep-fatigue interaction induced damage both at ambient and high temperature conditions. These alloys are extensively used for various structural applications such as aero-engine components etc. Reliable operation of such components depends on effective damage assessment during service. For offline damage assessment, excellent NDT techniques such as eddy current, ultrasonics, radiography etc. are available. But for online damage assessment, IR-thermography is one of the most popular techniques worldwide due to its non-intrusive and non-contact nature. Hence in the present investigation, for online damage assessment of creep-fatigue and fatigue damage, IR-thermography has been used. By holding the sample at peak stress, creep-fatigue interaction effect was introduced in the sample. Thermal profiles over fatigue and creep-fatigue samples were captured using online lock-in IR-thermography. Further, thermal modeling has been performed on the experimentally evaluated IR-data using first and second laws of thermodynamics. Thermal modeling effectively captured the partitioning of hysteresis energy into thermal losses and damage energy. This damage energy is responsible for creation of damage features such as voids in these samples. The damage energy for the sample tested with hold time (creep-fatigue) was more than that without hold time (pure fatigue) sample. Microscopic investigation further validated the higher amount of damage in creep-fatigue sample than fatigue sample. (author)

  10. A Comparative Study on the Laser Welding of Ti6Al4V Alloy Sheets in Flat and Horizontal Positions

    Directory of Open Access Journals (Sweden)

    Baohua Chang

    2017-04-01

    Full Text Available Laser welding has been increasingly utilized to manufacture a variety of components thanks to its high quality and speed. For components with complex shapes, the welding position needs be continuously adjusted during laser welding, which makes it necessary to know the effects of the welding position on the quality of the laser welds. In this paper, the weld quality under two (flat and horizontal welding positions were studied comparatively in the laser welding of Ti6Al4V titanium alloy, in terms of weld profiles, process porosity, and static tensile strengths. Results show that the flat welding position led to better weld profiles, less process porosity than that of the horizontal welding position, which resulted from the different actions of gravity on the molten weld metals and the different escape routes for pores under different welding positions. Although undercuts showed no association with the fracture positions and tensile strengths of the welds, too much porosity in horizontal laser welds led to significant decreases in the strengths and specific elongations of welds. Higher laser powers and travel speeds were recommended, for both flat and horizontal welding positions, to reduce weld porosity and improve mechanical properties.

  11. Effects of Nd:YAG laser pulse frequency on the surface treatment of Ti 6Al 4V alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gursel, Ali [International University of Sarajevo (Bosnia and Herzegovina). Dept. of Mechanical Engineering

    2016-07-01

    The desirable properties of titanium and titanium alloys, including excellent corrosion resistance, high strength to weight ratio and high operating temperature, have led to their successful application in various fields such as the medical and aerospace industries. Among the reliable treatment techniques, laser welding can provide significant advantages for the titanium alloys because of its precision, rapid processing capability and ability to control the welding parameters and their effects. The morphology and the quality of pulsed seam welds are directly or synergistically influenced by the Nd:YAG laser parameters of pulse shape, energy, duration, travel speed, peak power and frequency of repetition. In this study, a 1.5 mm thick Ti-6Al-4V alloy sheet surface was treated by SigmaLaser {sup registered} 300 Nd:YAG pulsed laser. The influence of the pulse frequency on seam morphology and surface effects was then investigated. The seam and surface quality were characterized in terms of weld morphology and microhardness. The results showed that, for Nd:YAG laser seams used for surface treatment, pulse repetition was more effective on the cooling rate than had been expected.

  12. Tool Wear Prediction in Ti-6Al-4V Machining through Multiple Sensor Monitoring and PCA Features Pattern Recognition.

    Science.gov (United States)

    Caggiano, Alessandra

    2018-03-09

    Machining of titanium alloys is characterised by extremely rapid tool wear due to the high cutting temperature and the strong adhesion at the tool-chip and tool-workpiece interface, caused by the low thermal conductivity and high chemical reactivity of Ti alloys. With the aim to monitor the tool conditions during dry turning of Ti-6Al-4V alloy, a machine learning procedure based on the acquisition and processing of cutting force, acoustic emission and vibration sensor signals during turning is implemented. A number of sensorial features are extracted from the acquired sensor signals in order to feed machine learning paradigms based on artificial neural networks. To reduce the large dimensionality of the sensorial features, an advanced feature extraction methodology based on Principal Component Analysis (PCA) is proposed. PCA allowed to identify a smaller number of features ( k = 2 features), the principal component scores, obtained through linear projection of the original d features into a new space with reduced dimensionality k = 2, sufficient to describe the variance of the data. By feeding artificial neural networks with the PCA features, an accurate diagnosis of tool flank wear ( VB max ) was achieved, with predicted values very close to the measured tool wear values.

  13. Tool Wear Prediction in Ti-6Al-4V Machining through Multiple Sensor Monitoring and PCA Features Pattern Recognition

    Directory of Open Access Journals (Sweden)

    Alessandra Caggiano

    2018-03-01

    Full Text Available Machining of titanium alloys is characterised by extremely rapid tool wear due to the high cutting temperature and the strong adhesion at the tool-chip and tool-workpiece interface, caused by the low thermal conductivity and high chemical reactivity of Ti alloys. With the aim to monitor the tool conditions during dry turning of Ti-6Al-4V alloy, a machine learning procedure based on the acquisition and processing of cutting force, acoustic emission and vibration sensor signals during turning is implemented. A number of sensorial features are extracted from the acquired sensor signals in order to feed machine learning paradigms based on artificial neural networks. To reduce the large dimensionality of the sensorial features, an advanced feature extraction methodology based on Principal Component Analysis (PCA is proposed. PCA allowed to identify a smaller number of features (k = 2 features, the principal component scores, obtained through linear projection of the original d features into a new space with reduced dimensionality k = 2, sufficient to describe the variance of the data. By feeding artificial neural networks with the PCA features, an accurate diagnosis of tool flank wear (VBmax was achieved, with predicted values very close to the measured tool wear values.

  14. Structure and tribological performance by nitrogen and oxygen plasma based ion implantation on Ti6Al4V alloy

    International Nuclear Information System (INIS)

    Feng Xingguo; Sun Mingren; Ma Xinxin; Tang Guangze

    2011-01-01

    Ti6Al4V alloy was implanted with nitrogen-oxygen mixture by using plasma based ion implantation (PBII) at pulsed voltage -10, -30 and -50 kV. The implantation was up to 6 x 10 17 ions/cm 2 fluence. The changes in chemical composition, structure and hardness of the modified surfaces were studied by XPS and nanoindentation measurements. According to XPS, it was found that the modified layer was predominantly TiO 2 , but contained small amounts of TiO, Ti 2 O 3 , TiN and Al 2 O 3 between the outmost layer and metallic substrate. Surface hardness and wear resistance of the samples increased significantly after PBII treatment, the wear rate of the sample implanted N 2 -O 2 mixture at -50 kV decreased eight times than the untreated one. The sample implanted N 2 -O 2 mixture showed better wear resistance than that of the sample only implanted oxygen at - 50 kV. The wear mechanism of untreated sample was abrasive-dominated and adhesive, and the wear scar of the sample implanted at -50 kV was characterized by abrasive wear-type ploughing.

  15. Characterization of Microstructure and Wear Resistance of PEO Coatings Containing Various Microparticles on Ti6Al4V Alloy

    Science.gov (United States)

    Li, Xinyi; Dong, Chaofang; Zhao, Qing; Pang, Yu; Cheng, Fasong; Wang, Shuaixing

    2018-02-01

    Titania-based composite coatings were prepared by plasma electrolytic oxidation (PEO) treatment of Ti6Al4V alloy in electrolyte with α-Al2O3, Cr2O3 or h-BN microparticles in suspension. The microstructure, composition of PEO composite coatings were analyzed by SEM, EDS and XRD. The wear resistance of composite ceramic coatings was studied by ball-on-disk wear test at ambient temperature and 300 °C. The results showed that the addition of microparticles accelerated the growth rate of PEO coating and changed the microstructure and composition of PEO coating. PEO coating was porous and mainly composed of rutile-TiO2, anatase-TiO2 and Al2TiO5. PEO/α-Al2O3 (Cr2O3 or h-BN) composite coating only had small micropores and appeared some α-Al2O3 (Cr2O3 or h-BN) phase. Besides, the addition of α-Al2O3 (Cr2O3 or h-BN) microparticles greatly improved the wear resistance of PEO coating. At ambient temperature, abrasive wear dominated the wear behavior of PEO coating, but abrasive wear and adhesive peel simultaneously happened at 300 °C. Whether at ambient temperature or 300 °C, PEO composite coating had better wear resistance than PEO coating. Besides, PEO/h-BN composite coating outperformed other composite coatings regardless of the temperature.

  16. Supersonic Plasma Spray Deposition of CoNiCrAlY Coatings on Ti-6Al-4V Alloy

    Science.gov (United States)

    Caliari, F. R.; Miranda, F. S.; Reis, D. A. P.; Essiptchouk, A. M.; Filho, G. P.

    2017-06-01

    Plasma spray is a versatile technology used for production of environmental and thermal barrier coatings, mainly in the aerospace, gas turbine, and automotive industries, with potential application in the renewable energy industry. New plasma spray technologies have been developed recently to produce high-quality coatings as an alternative to the costly low-pressure plasma-spray process. In this work, we studied the properties of as-sprayed CoNiCrAlY coatings deposited on Ti-6Al-4V substrate with smooth surface ( R a = 0.8 μm) by means of a plasma torch operating in supersonic regime at atmospheric pressure. The CoNiCrAlY coatings were evaluated in terms of their surface roughness, microstructure, instrumented indentation, and phase content. Static and dynamic depositions were investigated to examine their effect on coating characteristics. Results show that the substrate surface velocity has a major influence on the coating properties. The sprayed CoNiCrAlY coatings exhibit low roughness ( R a of 5.7 μm), low porosity (0.8%), excellent mechanical properties ( H it = 6.1 GPa, E it = 155 GPa), and elevated interface toughness (2.4 MPa m1/2).

  17. Some studies on cutting force and temperature in machining Ti-6Al-4V alloy using regression analysis and ANOVA

    Directory of Open Access Journals (Sweden)

    K.Satyanarayana

    2013-06-01

    Full Text Available The present work deals with the cutting forces and cutting temperature produced during turning of titanium alloy Ti-6Al-4V with PVD TiN coated tungsten carbide inserts under dry environment. The 1st order mathematical models are developed using multiple regression analysis and optimized the process parameters using contour plots. The model presented high determination coefficient (R2 = 0.964 and 0.989 explaining 96.4 % and 98.9 % of the variability in the cutting force and cutting temperature, which indicates the goodness of fit for the model and high significance of the model. The developed mathematical model correlates the relationship of the cutting force and temperature with the process parameters with good degree of approximation. From the contour plots, the optimal parametric combination for lowest cutting force is v 3 (75 m/min – f 1 (0.25 mm/rev. Similarly, the optimal parametric combination for minimum temperature is v 1 (45 m/min – f 1 (0.25 mm/rev. Cutting speed is found to be the most significance parameter on cutting forces followed by feed. Similarly, for cutting temperature, feed is found to be the most influencing parameter followed by cutting speed.

  18. PREDICTION OF SURFACE ROUGHNESS OF TI-6AL-4V IN ELECTRICAL DISCHARGE MACHINING: A REGRESSION MODEL

    Directory of Open Access Journals (Sweden)

    M.A. Maleque

    2011-12-01

    Full Text Available This paper develops a single order mathematical model for correlating various electrical discharge machining (EDM parameters and performance characteristics by utilizing relevant experimental data obtained through experimentation. In addition to the effect of peak ampere, the effect of pulse on time and pulse off time on surface roughness has also been investigated. Experiments have been conducted on titanium alloy Ti-6Al-4V with a copper electrode retaining negative polarity as per the Design of Experiments. Response surface methodology techniques are utilized to develop the mathematical model as well as to optimize the EDM parameters. An analysis of variance has been performed for the validity test of fit and adequacy of the proposed models. It can be seen that increasing pulse on time causes a fine surface until a certain value, beyond which the surface finish deteriorates. The excellent surface finish is investigated in this study for the case of pulse on time below 80 µs. This result acts as a guide for selecting the required process outputs and most economic industrial machining conditions for optimizing the input factors.

  19. Laser fabrication of Ag-HA nanocomposites on Ti6Al4V implant for enhancing bioactivity and antibacterial capability.

    Science.gov (United States)

    Liu, Xiangmei; Man, H C

    2017-01-01

    For titanium alloy implants, both surface bioactivity and antibacterial infection are the two critical factors in determining the success of clinical implantation of these metallic implants. In the present work, a novel nanocomposite layer of nano-silver-containing hydroxyapatite (Ag-HA) was prepared on the surface of biomedical Ti6Al4V by laser processing. Analysis using SEM, EDS and XRD shows the formation of an Ag-HA layer of about 200μm fusion bonded to the substrate. Mineralization tests in simulated body fluid (SBF) showed that laser fabricated Ag-HA nanocomposite layer favors the deposition of apatite on the surface of the implants. Antibacterial tests confirmed that all Ag-HA nanocomposite layers can kill bacteria while a higher Ag content would lower the cytocompatibility of these coatings. Cell viability decreases when the Ag content reaches 5% in these coatings, due to the larger amount of Ag leached out, as confirmed by ion release evaluation. Our results reveal that laser fabricated Ag-HA nanocomposite coatings containing 2% Ag show both excellent cytocompatibility and antibacterial capability. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. EFECT OF PLASMA IMMERSION ION IMPLANTATION TREATEMENT IN THE WEAR RESISTANCE OF Ti-6Al-4V ALLOY

    Directory of Open Access Journals (Sweden)

    Zepka, Susana

    2015-07-01

    Full Text Available The objective of this work was the evaluation of wear resistance of Ti-6Al-4V alloy after plasma immersion ion implantation (PIII in different immersion times. The goal of this process was the modification of surface properties of the alloy to obtain better tribology properties. In this process, atoms can be injected on the material´s surface changing the mechanical properties in the region near the surface independently of thermodynamics variables, as solubility and difusivity. The samples were submitted to 120 e 180 minutes of implantation at 250°C in the three samples for each condition. The wear analyses were made by pin-on-disk process, where the lost volumes and wear coefficients were compared in the samples. It was observed the decreasing of attrite coefficient and the lost volume of the material during wear test. The implanted sample by 180 minutes has showed the wear coefficient 35.12% lower in comparison of the sample without treatment, and 11.09% lower in comparison of implanted sample by 120 minutes. It can be observed that the sample implanted by 180 minutes showed lower wear coefficient.

  1. Characterization of laser peening-induced effects on a biomedical Ti6Al4V alloy by thermoelectric means

    Science.gov (United States)

    Carreón, Hector; Barriuso, Sandra; Porro, Juan Antonio; González-Carrasco, Jose Luis; Ocaña, José Luis

    2014-12-01

    Laser peening has recently emerged as a useful technique to overcome detrimental effects associated with other well-known surface modification processes such as shot peening or grit blasting used in the biomedical field. It is worthwhile to notice that besides the primary residual stress effect, thermally induced effects might also cause subtle surface and subsurface microstructural changes that might influence corrosion resistance and fatigue strength of structural components. In this work, plates of Ti-6Al-4V alloy of 7 mm in thickness were modified by laser peening without using a sacrificial outer layer. Irradiation by a Q-switched Nd-YAG laser (9.4-ns pulse length) working at the fundamental 1064-nm wavelength at 2.8 J/pulse and with water as a confining medium was used. Laser pulses with a 1.5-mm diameter at an equivalent overlapping density of 5000 cm-2 were applied. Attempts to analyze the global-induced effects after laser peening were addressed by using the contacting and noncontacting thermoelectric power techniques.

  2. Study on the Factors Affecting the Mechanical Behavior of Electron Beam Melted Ti6Al4V

    Science.gov (United States)

    Pirozzi, Carmine; Franchitti, Stefania; Borrelli, Rosario; Caiazzo, Fabrizia; Alfieri, Vittorio; Argenio, Paolo

    2017-09-01

    In this study, a mechanical characterization has been performed on EBM built Ti-6Al-4V tensile samples. The results of tensile tests have shown a different behavior between two sets of specimens: as built and machined ones. Supporting investigations have been carried out in order to physically explain the statistical difference of mechanical performances. Cylindrical samples which represent the tensile specimens geometry have been EBM manufactured and then investigated in their as built conditions from macrostructural and microstructural point of view. In order to make robust this study, cylindrical samples have been EBM manufactured with different size and at different height from build plate. The reason of this choice was arisen from the need of understanding if other factors as the massivity and specific location could affect the microstructure and defects generations consequently influencing the mechanical behavior of the EBMed components. The results of this study have proved that the irregularity of external circular surfaces of examined cylinders, reducing significantly the true cross section withstanding the applied load, has given a comprehensive physical explanation of the different tensile behavior of the two sets of tensile specimens.

  3. Laser gas-assisted processing of carbon coated and TiC embedded Ti-6Al-4V alloy surface

    Energy Technology Data Exchange (ETDEWEB)

    Yilbas, B.S., E-mail: bsyilbas@kfupm.edu.sa [Mechanical Engineering Department, King Fahd University of Petroleum and Minerals (Saudi Arabia); Akhtar, S.; Aleem, B.J. Abdul [Mechanical Engineering Department, King Fahd University of Petroleum and Minerals (Saudi Arabia); Karatas, C. [Faculty of Engineering, Hacettepe University (Turkey)

    2010-11-01

    Laser gas-assisted treatment of Ti-6Al-4V alloy surface is carried out. The alloy surface is initially coated by a carbon layer, in which the TiC particles are embedded prior to laser processing of the surface. The carbon coating with the presence of TiC particles on the workpiece surface is expected to result in carbonitride compound in the surface vicinity after the laser treatment process. Optical and scanning electron microscopes are used to examine the morphological and the metallurgical changes in the laser treated layer. The residual stress formed in the surface region after the laser treatment process is critical for the practical applications of the resulting surface. Therefore, the residual stress formed in the laser treated region is predicted from the analytically equation. The X-ray diffraction technique is incorporated to obtain the residual stress formed in the surface region. It is found that the residual stress predicted agrees with the X-ray diffraction data. The dense structures consisting of TiC{sub x}N{sub 1-x}, TiN{sub x}, Ti{sub 2}N, and TiC compounds are formed in the surface region of the treated layer. This, in turn, significantly increases the microhardness at the surface.

  4. Prediction of Surface Roughness When End Milling Ti6Al4V Alloy Using Adaptive Neurofuzzy Inference System

    Directory of Open Access Journals (Sweden)

    Salah Al-Zubaidi

    2013-01-01

    Full Text Available Surface roughness is considered as the quality index of the machine parts. Many diverse techniques have been applied in modelling metal cutting processes. Previous studies have revealed that artificial intelligence techniques are novel soft computing methods which fit the solution of nonlinear and complex problems like metal cutting processes. The present study used adaptive neurofuzzy inference system for the purpose of predicting the surface roughness when end milling Ti6Al4V alloy with coated (PVD and uncoated cutting tools under dry cutting conditions. Real experimental results have been used for training and testing of ANFIS models, and the best model was selected based on minimum root mean square error. A generalized bell-shaped function has been adopted as a membership function for the modelling process, and its numbers were changed from 2 to 5. The findings provided evidence of the capability of ANFIS in modelling surface roughness in end milling process and obtainment of good matching between experimental and predicted results.

  5. Tool Wear Prediction in Ti-6Al-4V Machining through Multiple Sensor Monitoring and PCA Features Pattern Recognition

    Science.gov (United States)

    2018-01-01

    Machining of titanium alloys is characterised by extremely rapid tool wear due to the high cutting temperature and the strong adhesion at the tool-chip and tool-workpiece interface, caused by the low thermal conductivity and high chemical reactivity of Ti alloys. With the aim to monitor the tool conditions during dry turning of Ti-6Al-4V alloy, a machine learning procedure based on the acquisition and processing of cutting force, acoustic emission and vibration sensor signals during turning is implemented. A number of sensorial features are extracted from the acquired sensor signals in order to feed machine learning paradigms based on artificial neural networks. To reduce the large dimensionality of the sensorial features, an advanced feature extraction methodology based on Principal Component Analysis (PCA) is proposed. PCA allowed to identify a smaller number of features (k = 2 features), the principal component scores, obtained through linear projection of the original d features into a new space with reduced dimensionality k = 2, sufficient to describe the variance of the data. By feeding artificial neural networks with the PCA features, an accurate diagnosis of tool flank wear (VBmax) was achieved, with predicted values very close to the measured tool wear values. PMID:29522443

  6. Analysis of surface roughness and cutting force during turning of Ti6Al4V ELI in dry environment

    Directory of Open Access Journals (Sweden)

    V. G. Sargade

    2016-04-01

    Full Text Available This paper investigates the effect of cutting parameters on the surface roughness and cutting force of titanium alloy Ti-6Al-4V ELI when turning using PVD TiAlN coated tool in dry environment. Taguchi L9 orthogonal array design of experiment was used for the turning experiment 2 factors and 3 levels. Turning parameters studied were cutting speed (50, 65, 80 m/min, feed rate (0.08, 0.15, 0.2 mm/rev and depth of cut 0.5 mm constant. Linear and second order model of the surface roughness and cutting force has been developed in terms of cutting speed and feed. The results show that the feed rate was the most impact factor controlling the cutting force and surface roughness produced. MINITAB 17software was used to develop a linear and second order model of surface roughness and cutting force. Optimum condition was at 66.97 m/min of cutting speed, 0.08 mm/rev of feed rate. Surface roughness 0.57μm and cutting force 54.02 N were obtained at the optimum condition. A good agreement between the experimental and predicted surface roughness and cutting force were observed.

  7. Strength, Fatigue, and Fracture Toughness of Ti-6Al-4V Liner from a Composite Over-Wrapped Pressure Vessel

    Science.gov (United States)

    Salem, Jonathan A.; Lerch, Brad; Thesken, John C.; Sutter, Jim; Russell, Richard

    2008-01-01

    It was demonstrated by way of experiment that Composite Over-wrapped Pressure Vessel (COPV) Ti-6Al-4V liner material can sustain the expected service loads and cycles. The experiments were performed as part of investigations on the residual life of COPV tanks being used in Space Shuttle Orbiters. Measured properties included tensile strength, compressive strength, reversed loading cycles to simulate liner proof strains, and cyclic fatigue loading to demonstrate the ability to sustain 1000 cycles after liner buckling. The liner material came from a salvaged 40 in. Columbia (orbiter 102) tank (SN029), and tensile strength measurements were made on both boss-transition (thick) and membrane regions (thin). The average measured yield strength was 131 ksi in the boss-transition and membrane regions, in good agreement with measurements made on 1970 s vintage forged plate stock. However, Young s modulus was 17.4+/-0.3 Msi, somewhat higher than typical handbook values (approx.16 Msi). The fracture toughness, as estimated from a failed fatigue specimen, was 74 ksi/sq in, in reasonable agreement with standardized measurements made on 1970 s vintage forged plate stock. Low cycle fatigue of a buckled test specimen implied that as-imprinted liners can sustain over 4000 load cycles.

  8. Fatigue Behavior and Modeling of Additively Manufactured Ti-6Al-4V Including Interlayer Time Interval Effects

    Science.gov (United States)

    Torries, Brian; Shamsaei, Nima

    2017-12-01

    The effects of different cooling rates, as achieved by varying the interlayer time interval, on the fatigue behavior of additively manufactured Ti-6Al-4V specimens were investigated and modeled via a microstructure-sensitive fatigue model. Comparisons are made between two sets of specimens fabricated via Laser Engineered Net Shaping (LENS™), with variance in interlayer time interval accomplished by depositing either one or two specimens per print operation. Fully reversed, strain-controlled fatigue tests were conducted, with fractography following specimen failure. A microstructure-sensitive fatigue model was calibrated to model the fatigue behavior of both sets of specimens and was found to be capable of correctly predicting the longer fatigue lives of the single-built specimens and the reduced scatter of the double-built specimens; all data points fell within the predicted upper and lower bounds of fatigue life. The time interval effects and the ability to be modeled are important to consider when producing test specimens that are smaller than the production part (i.e., property-performance relationships).

  9. Hybrid processing of Ti-6Al-4V using plasma immersion ion implantation combined with plasma nitriding

    Directory of Open Access Journals (Sweden)

    Silva Maria Margareth da

    2006-01-01

    Full Text Available Based on the fact that the Ti-6Al-4V alloy has good mechanical properties, excellent resistance to corrosion and also excellent biocompatibility, however with low wear resistance, this work aims to test plasma processes or combination of plasma and ion implantation processes to improve these characteristics. Two types of processing were used: two steps PIII (Plasma Immersion Ion Implantation combined with PN (Plasma Nitriding and single step PIII treatment. According to Auger Electron Spectroscopy (AES results, the best solution was obtained by PIII for 150 minutes resulting in ~ 65 nm of nitrogen implanted layer, while the sample treated with PIII (75 minutes and PN (75 minutes reached ~ 35 nm implanted layer. The improvement of surface properties could also be confirmed by the nanoindentation technique, with values of hardness increasing for both processes. AFM (Atomic Force Microscopy characterization showed that the single step PIII process presented greater efficiency than the duplex process (PIII + PN, probably due to the sputtering occurring during the second step (PN removing partially the implanted layer of first step (PIII.

  10. Ti-O-N/Ti composite coating on Ti-6Al-4V: surface characteristics, corrosion properties and cellular responses.

    Science.gov (United States)

    Cao, Xiao-Lin; Sun, Tao; Yu, Yonghao

    2015-03-01

    To enhance the corrosion resistance of Ti-6Al-4V and extend its lifetime in medical applications, Ti-O-N/Ti composite coating was synthesized on the surface via plasma immersion ion implantation and deposition (PIIID). Surface morphology and cross sectional morphology of the composite coating were characterized using atomic force microscopy and scanning electron microscopy, respectively. Although X-ray photoelectron spectroscopic analysis revealed that the Ti-O-N/Ti composite coating was composed of non-stoichiometric titanium oxide, titanium nitride and titanium oxynitride, no obvious characteristic peak corresponding to the crystalline phases of them was detected in the X-ray diffraction pattern. In accordance with Owens-Wendt equation, surface free energy of the uncoated and coated samples was calculated and compared. Moreover, the corrosion behavior of uncoated and coated samples was evaluated by means of electrochemical impedance spectroscopy measurement, and an equivalent circuit deriving from Randles model was used to fit Bode plots and describe the electrochemical processes occurring at the sample/electrolyte interface. On the basis of the equivalent circuit model, the resistance of the composite coating was 4.7 times higher than that of the passive layer on uncoated samples, indicating the enhanced corrosion resistance after PIIID treatment. Compared to uncoated Ti-6Al-V, Ti-O-N/Ti-coated samples facilitated ostoblast proliferation within 7 days of cell culture, while there was no statistically significant difference in alkaline phosphate activity between uncoated and coated samples during 21 days of cell culture.

  11. The effect of pulsed current electrodeposition parameters of calcium phosphates coating on Ti6Al4V ELI

    Science.gov (United States)

    Sierra-Herrera, D. K.; Sandoval-Amador, A.; Montañez-Supelano, N. D.; Y Peña-Ballesteros, D.

    2017-12-01

    Pulse current electrodeposition is a technique of special interest, due to the advantages it has, like easy operation, high control in the amount, homogeneity and purity of the deposited material, and low cost. This work studies the influence of the pulsed electrodeposition parameters variation on the characteristics of calcium phosphates coatings, including the composition, crystallinity and morphology. The influence of the current density and pulse on and off time on the physicochemical properties of the obtained coatings were evaluated. The coatings were electrodeposited on Ti6Al4V using Ca(NO3)2·H2O and NH4H2PO4 with a Ca/P molar ratio of 1.67. The coatings were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). The analysis of DRX confirmed the formation of HAP. The results revealed that the variation of the current density modified the morphology of the coating. Also, the amount of material deposited increases as the off-time pulse increases, allowing the diffusion of the ions in the solution towards the working electrode.

  12. Influence of Ultrasonic Surface Rolling on Microstructure and Wear Behavior of Selective Laser Melted Ti-6Al-4V Alloy

    Directory of Open Access Journals (Sweden)

    Zhen Wang

    2017-10-01

    Full Text Available The present article studied the effect of ultrasonic surface rolling process (USRP on the microstructure and wear behavior of a selective laser melted Ti-6Al-4V alloy. Surface characteristics were investigated using optical microscope, nano-indentation, scanning electron microscope, transmission electron microscope and laser scanning confocal microscope. Results indicated that the thickness of pore-free surfaces increased to 100~200 μm with the increasing ultrasonic surface rolling numbers. Severe work hardening occurred in the densified layer, resulting in the formation of refined grains, dislocation walls and deformation twins. After 1000 N 6 passes, about 15.5% and 14.1% increment in surficial Nano-hardness and Vickers-hardness was obtained, respectively. The hardness decreased gradually from the top surface to the substrate. Wear tests revealed that the friction coefficient declined from 0.74 (polished surface to 0.64 (USRP treated surface and the wear volume reduced from 0.205 mm−3 to 0.195 mm−3. The difference in wear volume between USRP treated and polished samples increased with sliding time. The enhanced wear resistance was concluded to be associated with the improvement of hardness and shear resistance and also the inhibition of delamination initiation.

  13. Tribocorrosion mechanisms of Ti6Al4V biomedical alloys in artificial saliva with different pHs

    Science.gov (United States)

    Licausi, M. P.; Igual Muñoz, A.; Amigó Borrás, V.

    2013-10-01

    Titanium and its alloys has been widely used for the design of dental implants because of its biocompatibility, mechanical properties and corrosion resistance. The powder-metallurgy process is a promising alternative to the casting fabrication process of titanium alloys for bone implants design as the porous structure mimics the natural bone structures, allowing the bone to grow into the pores which results in a better fixation of the artificial implant. However, under in vivo conditions the implants are subjected to tribocorrosion phenomenon, which consists in the degradation mechanisms due to the combined effect of wear and corrosion. The aim of this study is to evaluate the tribocorrosion behaviour of cast and sintered Ti6Al4V biomedical alloy for dental applications using the cast material as reference. Titanium samples were tested in artificial human saliva solution with three different pHs (3, 6, 9) and in an acidic saliva with 1000 ppm fluorides (AS-3-1000F-) by different electrochemical techniques (potentiodynamic curves, potentiostatic tests and tribo-electrochemical tests). Cast and sintered titanium alloys exhibit the same tribocorrosion mechanisms in AS independently of the pH which consists in plastic deformation with passive dissolution, but the addition of fluorides to the acidified solution changes the degradation mechanism towards active dissolution of the titanium alloys.

  14. Porosity, Microstructure, and Mechanical Properties of Ti-6Al-4V Alloy Parts Fabricated by Powder Compact Forging

    Science.gov (United States)

    Jia, Mingtu; Zhang, Deliang; Liang, Jiamiao; Gabbitas, Brian

    2017-04-01

    Ti-6Al-4V alloy powders produced using a hydrogenation-dehydrogenation process and a gas atomization process, respectively, were rapidly consolidated into near-net-shaped parts by powder compact forging. The porosity, microstructure, and tensile mechanical properties of specimens cut from regions at different distances from the side surfaces of the forged parts were examined. The regions near the side surfaces contained a fraction of pores due to the circumferential tensile strain arising during the powder compact forging process, and the porosity level decreased rapidly to zero with increasing the distance from the side surface. The forged parts had a fully lamellar structure with the α + β colony sizes and α lamella thickness changing little with the distance from the side surface. The specimens cut from the regions near the side surfaces had a lower yield strength and tensile strength. The correlation of porosity with the yield strength of the specimens suggested that the reduction of load bearing areas due to the porosity and unbonded or weakly bonded interparticle boundaries was not the only reason for the lower strength, and the stress concentration at the pores and associated with their geometry also played an important role in this. It is likely that the effect of stress concentration on yield strength reduction of the forged part increases with oxygen content. The Hall-Petch relationship of the yield strength and the average α lamella thickness suggested that the strength of the fully dense and fully consolidated forged parts was increased by oxygen solution strengthening.

  15. Influence of laser parameters in surface texturing of Ti6Al4V and AA2024-T3 alloys

    Science.gov (United States)

    Ahuir-Torres, J. I.; Arenas, M. A.; Perrie, W.; de Damborenea, J.

    2018-04-01

    Laser texturing can be used for surface modification of metallic alloys in order to improve their properties under service conditions. The generation of textures is determined by the relationship between the laser processing parameters and the physicochemical properties of the alloy to be modified. In the present work the basic mechanism of dimple generation is studied in two alloys of technological interest, titanium alloy Ti6Al4V and aluminium alloy AA2024-T3. Laser treatment was performed using a pulsed solid state Nd: Vanadate (Nd: YVO4) laser with a pulse duration of 10 ps, operating at a wavelength of 1064 nm and 5 kHz repetition rate. Dimpled surface geometries were generated through ultrafast laser ablation while varying pulse energy between 1 μJ and 20 μJ/pulse and with pulse numbers from 10 to 200 pulses per spot. In addition, the generation of Laser Induced Periodic Surface Structures (LIPSS) nanostructures in both alloys, as well as the formation of random nanostructures in the impact zones are discussed.

  16. Low temperature heat treatments of AA5754-Ti6Al4V dissimilar laser welds: Microstructure evolution and mechanical properties

    Science.gov (United States)

    Leo, P.; D'Ostuni, S.; Casalino, G.

    2018-03-01

    This paper presents the effects of the post welding heat treatments (PWHT) performed at 350 °C and 450 °C on the microstructure evolution and mechanical properties of AA5754 and Ti6Al4V dissimilar laser welds. The microstructure and tensile properties of the welds before and after low temperature treatment were analyzed. The off-set welding technique was applied to limit the formation of brittle intermetallic compounds during the welding process. The laser beam was directed onto the titanium side at a small distance from the aluminum edge. The keyhole formed and the full penetration was reached in the titanium side of the weld. Thereafter, the aluminum side melted as the heat that formed the keyhole transferred from the titanium fused zone. Two different energy lines (32 J/mm and 76 J/mm) were used. In this manner, a fused and a heat affected zones was revealed on both sides of the weld. Several intermetallic compounds formed in the intermetallic layer between the two metals. The thickness and the composition of the intermetallic layer depended on the welding parameters and the post welding heat treatment. The hardness and tensile properties of the welds before and after the post welding heat treatment were measured and analyzed.

  17. Corrosion Response of Ti6Al4V and Ti15Mo Dental Implant Alloys in the Presence of Listerine Oral Rinse

    Directory of Open Access Journals (Sweden)

    Rahul Bhola

    2013-01-01

    Full Text Available The influence of a commonly used antibacterial mouth rinse, Listerine, on the corrosion behavior of one of the commonly used titanium alloys Ti6Al4V (two-phase structure, i.e., α and β and a newer Ti15Mo (single β phase in normal saline solution has been investigated using electrochemical techniques. Interfacial electrochemical changes occurring at the oxide-solution interface have been analysed using EIS circuit modeling. Listerine acts as a corrosion inhibitor for Ti15Mo alloy and a corrosion promoter for Ti6Al4V alloy.

  18. On the Interface Generated by Hot Isostatic Pressing Compaction Process Between an AISI 304 Container and the Ti6Al4V Powders

    Science.gov (United States)

    Scherillo, Fabio; Aprea, Paolo; Astarita, Antonello; Scherillo, Antonella; Testani, Claudio; Squillace, Antonino

    2015-06-01

    In this work, the interface between a Ti6Al4V component made by Hot Isostatic Pressing and the AISI 304 container was studied in detail. The interface is dominated by interdiffusion with evident Kirkendall effect. Different intermetallic phases have been recognized. In particular, on the AISI 304 side of the interface, both χ and σ phases have been identified, whereas on the Ti6Al4V side λ phase (Laves), FeTi, (Fe,Ni)Ti, Ti2Ni, and β-Ti are present.

  19. Brasagem da zircônia metalizada com titânio à liga Ti-6Al-4V Brazing of metalized zirconia with titanium to Ti-6Al-4V alloy

    Directory of Open Access Journals (Sweden)

    J. S. Pimenta

    2012-06-01

    Full Text Available Zircônia tetragonal estabilizada com ítria foi mecanicamente metalizada com titânio e a condição de molhamento avaliada com as ligas convencionais Ag-28Cu e Au-18Ni. Estas dissolveram o revestimento de titânio para uma completa distribuição deste metal ativo na superfície cerâmica, gerando uma liga ativa in situ e possibilitando adequadas ligações químicas ao metal base na temperatura de união. Os melhores resultados de molhamento foram selecionados para brasagem indireta em forno de alto-vácuo nas juntas ZrO2/Ti-6Al-4V. Testes de detecção de vazamento de gás hélio foram realizados na interface de união das juntas; amostras removidas na seção transversal de juntas estanques foram examinadas por técnicas de análise microestrutural. Formou-se uma camada escura adjacente à cerâmica metalizada, responsável pelo molhamento ocasionado pela liga Ag-28Cu. Entretanto, o uso da liga Au-18Ni resultou em precipitação de intermetálicos e microtrincamento interfacial. Perfis de microdureza através da interface resultante até onde a zircônia mostrou típico escurecimento não indicaram alternância significativa entre medições consecutivas; os resultados dos ensaios de resistência mecânica à flexão-3p foram considerados satisfatórios.Yttria tetragonal zirconia polycrystal was mechanically metallized with titanium and the wetting behavior on the ceramic surface was analyzed using the conventional fillers Ag-28Cu and Au-18Ni. These alloys had dissolved the active metal coating, which acts to zirconia reduction on its surface and promoting suitable chemical bonding to the metallic member. Better wetting results were selected for indirect brazing in a high-vacuum furnace for ZrO2/Ti-6Al-4V simple butt joints. Helium gas leak detection was made at the joints interface; samples were removed from the tight joints cross-section and examined by microstructural analysis techniques and EDX analysis. There was formation of a dark

  20. Comportamiento microestructural de una aleación TI - 6 AL - 4 V empleada en pulpa lixiviada//Behaviour microstructure of an alloy TI - 6 AL - 4 V used in leached pulp

    Directory of Open Access Journals (Sweden)

    Rodney E. Correa‐Suárez

    2014-01-01

    Full Text Available En el trabajo se determina el comportamiento microestructural de la aleación Ti - 6 Al - 4 V del tipo α + β de la cual se fabrica el cuerpo de las válvulas que trabajan en la línea de pulpa lixiviada, que por efecto del fluido sufren perforaciones y son recuperadas por proceso de soldadura, en el establecimiento del ciclo térmico de soldadura se tuvo en cuenta la intensidad de corriente, el voltaje del arco eléctrico, la velocidad de soldadura y la energía lineal del proceso de soldadura. Como material de aporte se seleccionó el electrodo consumible ERTi – 2. De la válvula dañada se seleccionaron muestras de diferentes zonas, las cuales se caracterizaron en dependencia con la afectación de la pulpa lixiviada caliente.Palabras claves: pulpa lixiviada, ciclo térmico, microestructural, titanio, isotermas.______________________________________________________________________________AbstractIn this article, we study various solution schemes reported in the literature, which deal with the problem of irregular parts distribution on flat surfaces with two-dimensional nesting. Different solution schemes were analyzed, which they consider to be the real geometry of the part, during the evaluation and positioningthem on the surface to be cut, ensuring the best use of the material. The proposed scheme is characterized by a graphic treatment of the pieces that can accelerate the process of recognition and evaluation of options coupling between them, as well as the creation of cluster populations growing to its final location on the surface to be cut. In the generation of populations of possible solutions, using analgorithm based on the method of integration variables, in addition is made comparing the results obtained by the proposed method with other results generated by procedures developed by different authors, achieving improved use.Key words: leached pulp, cycle thermal, microstructure, titanium, isotherm.

  1. Adhesion measurement of highly-ordered TiO2 nanotubes on Ti-6Al-4V alloy

    Directory of Open Access Journals (Sweden)

    Masoud Sarraf

    2017-12-01

    Full Text Available Self-assembled nanotubular arrays on Ti alloys could be used for more effective implantable devices in various medical approaches. In the present work, the adhesion of TiO2 nanotubes (TiO2 NTs on Ti-6Al-4V (Ti64 was investigated by laser spallation and scratch test techniques. At first, electrochemical anodization was performed in an ammonium fluoride solution dissolved in a 90:10 ethane-1,2-diol (ethylene glycol and water solvent mixture. This process was performed at room temperature (23 °C at a steady potential of 60 V for 1 h. Next, the TiO2 nanotubes layer was heat-treated to improve the adhesion of the coating. The formation of selforganized TiO2 nanotubes as well as the microstructural evolution, are strongly dependent on the processing parameters and subsequent annealing. From microscopic analysis, highly oriented arrays of TiO2 nanotubes were grown by thermal treatment for 90 min at 500 °C. Further heat treatment above 500 °C led to the detachment of the nanotubes and the complete destruction of the nanotubes occurred at temperature above 700 °C. Scratch test analysis over a constant scratch length (1000 µm indicated that the failure point was shifted from 247.4 to 557.9 µm while the adhesion strength was increased from ∼862 to ∼1814 mN after annealing at 500 °C. The adhesion measurement determined by laser spallation technique provided an intrinsic adhesion strength of 51.4 MPa for the TiO2 nanotubes on the Ti64 substrate.

  2. A Novel Investigation of the Formation of Titanium Oxide Nanotubes on Thermally Formed Oxide of Ti-6Al-4V.

    Science.gov (United States)

    Butt, Arman; Hamlekhan, Azhang; Patel, Sweetu; Royhman, Dmitry; Sukotjo, Cortino; Mathew, Mathew T; Shokuhfar, Tolou; Takoudis, Christos

    2015-10-01

    Traditionally, titanium oxide (TiO2) nanotubes (TNTs) are anodized on Ti-6Al-4V alloy (Ti-V) surfaces with native TiO2 (amorphous TiO2); subsequent heat treatment of anodized surfaces has been observed to enhance cellular response. As-is bulk Ti-V, however, is often subjected to heat treatment, such as thermal oxidation (TO), to improve its mechanical properties. Thermal oxidation treatment of Ti-V at temperatures greater than 200°C and 400°C initiates the formation of anatase and rutile TiO2, respectively, which can affect TNT formation. This study aims at understanding the TNT formation mechanism on Ti-V surfaces with TO-formed TiO2 compared with that on as-is Ti-V surfaces with native oxide. Thermal oxidation-formed TiO2 can affect TNT formation and surface wettability because TO-formed TiO2 is expected to be part of the TNT structure. Surface characterization was carried out with field emission scanning electron microscopy, energy dispersive x-ray spectroscopy, water contact angle measurements, and white light interferometry. The TNTs were formed on control and 300°C and 600°C TO-treated Ti-V samples, and significant differences in TNT lengths and surface morphology were observed. No difference in elemental composition was found. Thermal oxidation and TO/anodization treatments produced hydrophilic surfaces, while hydrophobic behavior was observed over time (aging) for all samples. Reduced hydrophobic behavior was observed for TO/anodized samples when compared with control, control/anodized, and TO-treated samples. A method for improved surface wettability and TNT morphology is therefore discussed for possible applications in effective osseointegration of dental and orthopedic implants.

  3. Enhanced tribological behavior of anodic films containing SiC and PTFE nanoparticles on Ti6Al4V alloy

    International Nuclear Information System (INIS)

    Li, Songmei; Zhu, Mengqi; Liu, Jianhua; Yu, Mei; Wu, Liang; Zhang, Jindan; Liang, Hongxing

    2014-01-01

    Highlights: • An environmental friendly sodium tartrate (C 4 O 6 H 4 Na 2 ) electrolyte is used. • SiC and PTFE nanoparticles reduce friction coefficient of composite films. • SiC and PTFE nanoparticles demonstrate a favorable synergistic effect on improving tribological properties of composite films. • Lubricating mechanisms of SiC and PTFE nanoparticles are discussed. - Abstract: Anodic films containing SiC and polytetrafluoroethylene (PTFE) nanoparticles were successfully fabricated on Ti6Al4V alloy by using anodic oxidation method in an environmental friendly electrolyte. The morphology, structure and composition of the films were studied with the scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results showed that the film contained a layered structure and have a surface full of petaloid bulges, which was totally different from the common anodic oxide film of the porous kind. The tribological properties of the films were investigated with dry friction tests in terms of the friction coefficient, wear rate and the morphology of worn surfaces. The results indicated that the SiC/PTFE composite film exhibited much better anti-wear and anti-friction performances than that of the SiC composite film, the PTFE composite film and the ordinary film without nanoparticles. The SiC/PTFE composite film has friction coefficient of 0.1 and wear rate of 20.133 mg/m, which was decreased respectively by 80% and 44.5% compared with that of the ordinary film. The lubricating mechanisms of the composite film containing SiC and PTFE nanoparticles were discussed. PTFE nanoparticles could lead to the formation of lubricating layer while SiC nanoparticles inside the lubricating layer turned sliding friction to rolling friction

  4. Synthesis and Evaluation of A High Precision 3D-Printed Ti6Al4V Compliant Parallel Manipulator

    Science.gov (United States)

    Pham, Minh Tuan; Teo, Tat Joo; Huat Yeo, Song; Wang, Pan; Nai, Mui Ling Sharon

    2017-12-01

    A novel 3D printed compliant parallel manipulator (CPM) with θX - θX - Z motions is presented in this paper. This CPM is synthesized using the beam-based method, a new structural optimization approach, to achieve optimized stiffness properties with targeted dynamic behavior. The CPM performs high non-actuating stiffness based on the predicted stiffness ratios of about 3600 for translations and 570 for rotations, while the dynamic response is fast with the targeted first resonant mode of 100Hz. A prototype of the synthesized CPM is fabricated using the electron beam melting (EBM) technology with Ti6Al4V material. Driven by three voice-coil (VC) motors, the CPM demonstrated a positioning resolution of 50nm along the Z axis and an angular resolution of ~0.3 “about the X and Y axes, the positioning accuracy is also good with the measured values of ±25.2nm and ±0.17” for the translation and rotations respectively. Experimental investigation also shows that this large workspace CPM has a first resonant mode of 98Hz and the stiffness behavior matches the prediction with the highest deviation of 11.2%. Most importantly, the full workspace of 10° × 10° × 7mm of the proposed CPM can be achieved, that demonstrates 3D printed compliant mechanisms can perform large elastic deformation. The obtained results show that CPMs printed by EBM technology have predictable mechanical characteristics and are applicable in precise positioning systems.

  5. Simulation investigation of thermal phase transformation and residual stress in single pulse EDM of Ti-6Al-4V

    Science.gov (United States)

    Tang, Jiajing; Yang, Xiaodong

    2018-04-01

    The thermal phase transformation and residual stress are ineluctable in the electrical discharge machining (EDM) process, and they will greatly affect the working performances of the machined surface. This paper presents a simulation study on the thermal phase transformation and residual stress in single-pulse EDM of Ti-6Al-4V, which is the most popular titanium alloy in fields such as aircraft engine and some other leading industries. A multi-physics model including thermal, hydraulic, metallography and structural mechanics was developed. Based on the proposed model, the thickness and metallographic structure of the recast layer and heat affected layer (HAZ) were investigated. The distribution and characteristics of residual stress around the discharge crater were obtained. The recast layer and HAZ at the center of crater are found to be the thinnest, and their thicknesses gradually increase approaching the periphery of the crater. The recast layer undergoes a complete α‧ (martensitic) transformation, while the HAZ is mainly composed by the α  +  β  +  α‧ three-phase microstructure. Along the depth direction of crater, the Von Mises stress increases first and then decreases, reaching its maximal value near the interface of recast layer and HAZ. In the recast layer, both compressive stress component and tensile stress component are observed. ANOVA results showed that the influence of discharge current on maximal tensile stress is more significant than that of pulse duration, while the pulse duration has more significant influence on average thickness of the recast layer and the depth location of the maximal tensile stress. The works conducted in this study will help to evaluate the quality and integrity of EDMed surface, especially when the non-destructive testing is difficult to achieve.

  6. Customized a Ti6Al4V Bone Plate for Complex Pelvic Fracture by Selective Laser Melting.

    Science.gov (United States)

    Wang, Di; Wang, Yimeng; Wu, Shibiao; Lin, Hui; Yang, Yongqiang; Fan, Shicai; Gu, Cheng; Wang, Jianhua; Song, Changhui

    2017-01-04

    In pelvic fracture operations, bone plate shaping is challenging and the operation time is long. To address this issue, a customized bone plate was designed and produced using selective laser melting (SLM) technology. The key steps of this study included designing the customized bone plate, metal 3D printing, vacuum heat treatment, surface post-processing, operation rehearsal, and clinical application and evaluation. The joint surface of the bone plate was placed upwards with respect to the build platform to keep it away from the support and to improve the quality of the joint surface. Heat conduction was enhanced by adding a cone-type support beneath the bone plate to prevent low-quality fabrication due to poor heat conductivity of the Ti-6Al-4V powder. The residual stress was eliminated by exposing the SLM-fabricated titanium-alloy bone plate to a vacuum heat treatment. Results indicated that the bone plate has a hardness of HV1 360-HV1 390, an ultimate tensile strength of 1000-1100 MPa, yield strength of 900-950 MPa, and an elongation of 8%-10%. Pre-operative experiments and operation rehearsal were performed using the customized bone plate and the ABC-made pelvic model. Finally, the customized bone plate was clinically applied. The intraoperative C-arm and postoperative X-ray imaging results indicated that the customized bone plate matched well to the damaged pelvis. The customized bone plate fixed the broken bone and guides pelvis restoration while reducing operation time to about two hours. The customized bone plate eliminated the need for preoperative titanium plate pre-bending, thereby greatly reducing surgical wounds and operation time.

  7. Microstructure and mechanical behavior of porous Ti-6Al-4V parts obtained by selective laser melting.

    Science.gov (United States)

    Sallica-Leva, E; Jardini, A L; Fogagnolo, J B

    2013-10-01

    Rapid prototyping allows titanium porous parts with mechanical properties close to that of bone tissue to be obtained. In this article, porous parts of the Ti-6Al-4V alloy with three levels of porosity were obtained by selective laser melting with two different energy inputs. Thermal treatments were performed to determine the influence of the microstructure on the mechanical properties. The porous parts were characterized by both optical and scanning electron microscopy. The effective modulus, yield and ultimate compressive strength were determined by compressive tests. The martensitic α' microstructure was observed in all of the as-processed parts. The struts resulting from the processing conditions investigated were thinner than those defined by CAD models, and consequently, larger pores and a higher experimental porosity were achieved. The use of the high-energy input parameters produced parts with higher oxygen and nitrogen content, their struts that were even thinner and contained a homogeneous porosity distribution. Greater mechanical properties for a given relative density were obtained using the high-energy input parameters. The as-quenched martensitic parts showed yield and ultimate compressive strengths similar to the as-processed parts, and these were greater than those observed for the fully annealed samples that had the lamellar microstructure of the equilibrium α+β phases. The effective modulus was not significantly influenced by the thermal treatments. A comparison between these results and those of porous parts with similar geometry obtained by selective electron beam melting shows that the use of a laser allows parts with higher mechanical properties for a given relative density to be obtained. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Customized a Ti6Al4V Bone Plate for Complex Pelvic Fracture by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Di Wang

    2017-01-01

    Full Text Available In pelvic fracture operations, bone plate shaping is challenging and the operation time is long. To address this issue, a customized bone plate was designed and produced using selective laser melting (SLM technology. The key steps of this study included designing the customized bone plate, metal 3D printing, vacuum heat treatment, surface post-processing, operation rehearsal, and clinical application and evaluation. The joint surface of the bone plate was placed upwards with respect to the build platform to keep it away from the support and to improve the quality of the joint surface. Heat conduction was enhanced by adding a cone-type support beneath the bone plate to prevent low-quality fabrication due to poor heat conductivity of the Ti-6Al-4V powder. The residual stress was eliminated by exposing the SLM-fabricated titanium-alloy bone plate to a vacuum heat treatment. Results indicated that the bone plate has a hardness of HV1 360–HV1 390, an ultimate tensile strength of 1000–1100 MPa, yield strength of 900–950 MPa, and an elongation of 8%–10%. Pre-operative experiments and operation rehearsal were performed using the customized bone plate and the ABC-made pelvic model. Finally, the customized bone plate was clinically applied. The intraoperative C-arm and postoperative X-ray imaging results indicated that the customized bone plate matched well to the damaged pelvis. The customized bone plate fixed the broken bone and guides pelvis restoration while reducing operation time to about two hours. The customized bone plate eliminated the need for preoperative titanium plate pre-bending, thereby greatly reducing surgical wounds and operation time.

  9. NiTi intermetallic surface coatings by laser metal deposition for improving wear properties of Ti-6Al-4V substrates

    CSIR Research Space (South Africa)

    Mokgalaka, MN

    2014-03-01

    Full Text Available The NiTi intermetallic possesses a number of good properties, such as high wear, oxidation, and corrosion resistance. This paper focuses on the deposition of NiTi intermetallic coatings on Ti6Al4V substrate by laser melting of Ti and Ni elemental...

  10. Effect of the overlapping factor on the microstructure and mechanical properties of pulsed Nd:YAG laser welded Ti6Al4V sheets

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Xiao-Long; Liu, Jing; Zhang, Lin-Jie, E-mail: zhanglinjie@mail.xjtu.edu.cn; Zhang, Jian-Xun

    2014-07-01

    The effect of the overlapping factor on the microstructures and mechanical properties of pulsed Nd:YAG laser welded Ti6Al4V alloy sheets was investigated by microstructural observations, microhardness tests, tensile tests and fatigue tests. A microstructural examination shows that by increasing the overlapping factor, the grains in the fusion zone become coarser, and the width of the heat affected zone increases. As overlapping factor increases, the width of region composed completely of martensite α′ and the secondary α phase in the heat affected zone increases, consequently the gradient of microstructure along the direction from the fusion zone to base metal decreases, so does the gradient of microhardness. The results of tensile and fatigue tests reveal that the joints made using medium overlapping factor exhibit better mechanical properties than those welded with low and high overlapping factors. Based on the experimental results, it can be stated that a sound weld of Ti6Al4V alloy can be obtained if an appropriate overlapping factor is used. - Highlights: • The weld quality of Ti6Al4V alloy under various overlapping factors was assessed. • Tensile and fatigue tests were conducted with as-welded specimen. • Localized strain across the weld was measured using DIC photogrammetry system. • A sound weld of Ti6Al4V alloy is obtained by using right overlapping factor.

  11. A comparison of corrosion, tribocorrosion and electrochemical impedance properties of pure Ti and Ti6Al4V alloy treated by micro-arc oxidation process

    Science.gov (United States)

    Fazel, M.; Salimijazi, H. R.; Golozar, M. A.; Garsivaz jazi, M. R.

    2015-01-01

    In this paper, the micro-arc oxidation (MAO) coatings were performed on pure Ti and Ti6Al4V samples at 180 V. The results indicated that unlike the volcanic morphology of oxide layer on pure Ti, a cortex-like morphology with irregular vermiform slots was seen on MAO/Ti6Al4V sample. According to polarization curves, the corrosion resistance of untreated samples was significantly increased by MAO process. The electrochemical impedance spectroscopy analysis showed a lower capacitance of barrier layer (led to higher resistance) for MAO/Ti specimens. This indicates that corrosive ions diffusion throughout the oxide film would be more difficult resulted in a higher corrosion resistance. Tribocorrosion results illustrated that the potential of untreated samples was dropped sharply to very low negative values. However, the lower wear volume loss was achieved for Ti6Al4V alloy. SEM images of worn surfaces demonstrated the local detachment of oxide layer within the wear track of MAO/Ti sample. Conversely, no delamination was detected in MAO/Ti6Al4V and a mild abrasive wear was the dominant mechanism.

  12. Microstructural and tribological behavior of in situ synthesized Ti/Co coatings on Ti-6Al-4V alloy using laser surface cladding technique

    CSIR Research Space (South Africa)

    Adesina, OS

    2017-11-01

    Full Text Available Technol https://doi.org/10.1007/s00170-017-1300-3 Microstructural and tribological behavior of in situ synthesized Ti/Co coatings on Ti-6Al-4V alloy using laser surface cladding technique O. S. Adesina, A. P. I. Popoola, S. L. Pityana, D. T...

  13. Interaction between Yttria fully stabilized Zirconia or Yttria-Zirconia blended face-coat with Ti6Al4V during investment casting

    CSIR Research Space (South Africa)

    Mutombo, K

    2014-10-01

    Full Text Available The interaction between the Ti6Al4V alloy and the mould materials was investigated. The alpha-case was characterized by Vickers hardness tester, optical and scanning electron microscopy equipped with electron dispersive X-ray spectrometry (EDX). X-ray...

  14. Microstructure, microhardness and corrosion resistance of remelted TiG2 and Ti6Al4V by a high power diode laser

    Energy Technology Data Exchange (ETDEWEB)

    Amaya-Vazquez, M.R. [Laboratorio de Corrosion y Proteccion, Universidad de Cadiz, Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica, Avda. Republica Saharaui s/n, 11510 Puerto Real, Cadiz (Spain); Sanchez-Amaya, J.M., E-mail: josemaria.sanchez@uca.es [Titania, Ensayos y Proyectos Industriales S.L., Ctra Sanlucar A-2001 Km 7,5, Parque Tecnologico TecnoBahia-Edif. RETSE Nave 4, 11500 El Puerto de Santa Maria, Cadiz (Spain); Departamento de Fisica Aplicada, CASEM, Avda. Republica Saharaui s/n, 11510-Puerto Real, Cadiz (Spain); Boukha, Z.; Botana, F.J. [Laboratorio de Corrosion y Proteccion, Universidad de Cadiz, Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica, Avda. Republica Saharaui s/n, 11510 Puerto Real, Cadiz (Spain)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Laser remelting of TiG2 and Ti6Al4V is performed with argon shielded diode laser. Black-Right-Pointing-Pointer Microstructure, microhardness and corrosion of remelted samples are deeply analysed. Black-Right-Pointing-Pointer Microstructural changes of laser remelted TiG2 lead to microhardness increase. Black-Right-Pointing-Pointer Remelted Ti6Al4V presents microhardness increase and corrosion improvement. Black-Right-Pointing-Pointer Martensite depth in remelted Ti6Al4V is linearly proportional to laser fluence. - Abstract: The high strength, low density and superior corrosion resistance allow titanium alloys to be widely employed in different industrial applications. The properties of these alloys can be modulated by different heat treatments, including laser processing. In the present paper, laser remelting treatments, performed with a high power diode laser, were applied to samples of two titanium alloys (TiG2 and Ti6Al4V). The influence of the applied laser fluence on microstructure, microhardness and corrosion resistance is investigated. Results show that laser remelting treatments with appropriate fluences provoke microstructural changes leading to microhardness increase and corrosion resistance improvement.

  15. Effects of Traverse Scanning Speed of Spray Nozzle on the Microstructure and Mechanical Properties of Cold-Sprayed Ti6Al4V Coatings

    Science.gov (United States)

    Tan, Adrian Wei-Yee; Sun, Wen; Phang, Yun Peng; Dai, Minghui; Marinescu, Iulian; Dong, Zhili; Liu, Erjia

    2017-10-01

    Cold spray has the potential to restore damaged aerospace components made from titanium alloy, Ti6Al4V at low temperature (200-400 °C). Traverse scanning speed during deposition is one of the key factors that affect the quality of the Ti6Al4V coatings as it influences the thermal build-up and coating thickness per pass. As there are fewer reported studies on this, this work investigated the effects of different traverse scanning speeds (100, 300 and 500 mm/s) of cold spray nozzle on the microstructure and mechanical properties of cold-sprayed Ti6Al4V coatings. The cross-sectional analysis showed coating porosities reduces with slower traverse speed, from 3.2 to 0.5%. In addition, the microhardness of the coatings increased from about 361-385 HV due to strain hardening. However, the adhesion strength of the coatings to the substrates significantly decreased with reduced traverse speed from about 60 MPa (glue failure) at 500 mm/s to 2.5 MPa (interface failure) at 100 mm/s. Therefore, this study revealed that the control of heat build-up and thickness per pass during the cold spray deposition of the Ti6Al4V coatings is crucial to attain the desirable properties of the coatings.

  16. Significantly enhanced creep resistance of low volume fraction in-situ TiBw/Ti6Al4V composites by architectured network reinforcements

    Science.gov (United States)

    Wang, S.; Huang, L. J.; Geng, L.; Scarpa, F.; Jiao, Y.; Peng, H. X.

    2017-01-01

    We present a new class of TiBw/Ti6Al4V composites with a network reinforcement architecture that exhibits a significant creep resistance compared to monolithic Ti6Al4V alloys. Creep tests performed at temperatures between 773 K and 923 K and stress range of 100 MPa-300 MPa indicate both a significant improvement of the composites creep resistance due to the network architecture made by the TiB whiskers (TiBw), and a decrease of the steady-state creep rates by augmenting the local volume fractions of TiBw in the network region. The deformation behavior is driven by a diffusion-controlled dislocation climb process. Moreover, the activation energies of these composites are significantly higher than that of Ti6Al4V alloys, indicating a higher creep resistance. The increase of the activation energy can be attributed to the TiBw architecture that severely impedes the movements of dislocation and grain boundary sliding and provides a tailoring of the stress transfer. These micromechanical mechanisms lead to a remarkable improvement of the creep resistance of these networked TiBw/Ti6Al4V composites featuring the special networked architecture.

  17. Influence of heat treatments on the microstructure and tensile behaviour of selective laser melting-produced TI-6AL-4V parts

    Directory of Open Access Journals (Sweden)

    Ter Haar, Gerrit Matthys

    2016-11-01

    Full Text Available In industry, post-process heat treatments of Ti-6Al-4V are performed with the aim of improving its tensile behaviour. While heat treatments of wrought Ti6Al4V have been standardised (e.g., Aerospace Material Specification H-81200, heat treatments of selective laser melting (SLM-produced Ti-6Al-4V lacks research and understanding. Significant concern exists about SLM Ti6-Al-4V’s achievable ductility attributed to its martensitic (α’ phase. In this research, heat treatments at a range of temperatures are applied to SLM-produced Ti-6Al-4V tensile samples. Microstructural analysis (both optically and through electron backscatter diffraction was used to identify links between heat treatments and microstructure. Subsequently, uniaxial tensile tests were performed to determine the respective tensile properties of all samples. Correlations in the data show a significant loss in strength with respect to an increase in annealing temperature due to grain growth, while no noticeable trend was observed for fracture strain with regard to annealing temperatures.

  18. Microstructural and surface modifications and hydroxyapatite coating of Ti-6Al-4V triply periodic minimal surface lattices fabricated by selective laser melting.

    Science.gov (United States)

    Yan, Chunze; Hao, Liang; Hussein, Ahmed; Wei, Qingsong; Shi, Yusheng

    2017-06-01

    Ti-6Al-4V Gyroid triply periodic minimal surface (TPMS) lattices were manufactured by selective laser melting (SLM). The as-built Ti-6Al-4V lattices exhibit an out-of-equilibrium microstructure with very fine α' martensitic laths. When subjected to the heat treatment of 1050°C for 4h followed by furnace cooling, the lattices show a homogenous and equilibrium lamellar α+β microstructure with less dislocation and crystallographic defects compared with the as-built α' martensite. The as-built lattices present very rough strut surfaces bonded with plenty of partially melted metal particles. The sand blasting nearly removed all the bonded metal particles, but created many tiny cracks. The HCl etching eliminated these tiny cracks, and subsequent NaOH etching resulted in many small and shallow micro-pits and develops a sodium titanate hydrogel layer on the surfaces of the lattices. When soaked in simulated body fluid (SBF), the Ti-6Al-4V TPMS lattices were covered with a compact and homogeneous biomimetic hydroxyapatite (HA) layer. This work proposes a new method for making Ti-6Al-4V TPMS lattices with a homogenous and equilibrium microstructure and biomimetic HA coating, which show both tough and bioactive characteristics and can be promising materials usable as bone substitutes. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Influence of process parameters on layer build-up and microstructure of Ti6Al4V (ELI) alloy on the optomec LENS

    CSIR Research Space (South Africa)

    Arthur, N

    2016-11-01

    Full Text Available such as laser power, scanning speed and powder flow rate in order to determine their influence on the physical properties, as well as microstructure of Ti6Al4V ELI (Extra-Low Interstitials) build-ups conducted on the LENS® system for the qualification...

  20. Morphology, microstructure, and hardness of titanium (Ti-6Al-4V) blocks deposited by wire-feed additive layer manufacturing (ALM)

    International Nuclear Information System (INIS)

    Brandl, Erhard; Schoberth, Achim; Leyens, Christoph

    2012-01-01

    Highlights: ► The microstructure and hardness of deposited Ti-6Al-4V blocks are investigated. ► Hardness is influenced by post heat treatment rather than by process parameters. ► Microstructure within the prior β-grains varies to some extent from grain to grain. ► A 600 °C/4 h treatment significantly increased the average hardness. - Abstract: Additive layer manufacturing offers a potential for time and cost savings, especially for aerospace components made from costly titanium alloys. In this paper, the morphology, microstructure, chemical composition, and hardness of additive manufactured Ti-6Al-4V blocks are investigated and discussed. Blocks (7 beads wide, 7 layers high) were deposited using Ti-6Al-4V wire and a Nd:YAG laser. Two different sets of parameters are used and three different post heat treatment conditions (as-built, 600 °C/4 h, 1200 °C/2 h) are investigated. The experiments reveal elementary properties of additive manufactured Ti-6Al-4V material in correlation to process parameters and heat treatments, which are discussed comprehensively.

  1. Effects of Plasma ZrN Metallurgy and Shot Peening Duplex Treatment on Fretting Wear and Fretting Fatigue Behavior of Ti6Al4V Alloy.

    Science.gov (United States)

    Tang, Jingang; Liu, Daoxin; Zhang, Xiaohua; Du, Dongxing; Yu, Shouming

    2016-03-23

    A metallurgical zirconium nitride (ZrN) layer was fabricated using glow metallurgy using nitriding with zirconiuming prior treatment of the Ti6Al4V alloy. The microstructure, composition and microhardness of the corresponding layer were studied. The influence of this treatment on fretting wear (FW) and fretting fatigue (FF) behavior of the Ti6Al4V alloy was studied. The composite layer consisted of an 8-μm-thick ZrN compound layer and a 50-μm-thick nitrogen-rich Zr-Ti solid solution layer. The surface microhardness of the composite layer is 1775 HK 0.1 . A gradient in cross-sectional microhardness distribution exists in the layer. The plasma ZrN metallurgical layer improves the FW resistance of the Ti6Al4V alloy, but reduces the base FF resistance. This occurs because the improvement in surface hardness results in lowering of the toughness and increasing in the notch sensitivity. Compared with shot peening treatment, plasma ZrN metallurgy and shot peening composite treatment improves the FW resistance and enhances the FF resistance of the Ti6Al4V alloy. This is attributed to the introduction of a compressive stress field. The combination of toughness, strength, FW resistance and fatigue resistance enhance the FF resistance for titanium alloy.

  2. A Novel Extrusion for Manufacturing TiBw/Ti6Al4V Composite Tubes with a Quasi-Continuous Reinforced Structure.

    Science.gov (United States)

    Yang, Jianlei; Jiao, Xueyan; Chen, Wenzhen; Zhang, Wencong; Wang, Guofeng

    2017-03-31

    The present work introduces a novel extrusion with filler material to produce the high-performance TiBw/Ti-6Al-4V composite tube with a quasi-continuous reinforced structure. A simulation was adopted to study the effect of the filler material on the shape accuracy of the tubes. Based on the simulation results, the flow stress of the filler material was not the important factor, but the friction coefficient between the filler and TiBw/Ti-6Al-4V composite and the canning shape were critical to the tube precision. The microstructure and mechanical performance for the as-extruded TiBw/Ti-6Al-4V composite tubes were systematically investigated. After extrusion, the transverse section microstructure of the TiBw/Ti6Al4V composite tube remained quasi-continuous and the TiBw were rotated to align the extrusion direction. Moreover, the tensile strength and elongation reached 1240 MPa and 13.5%, resulting from dynamic recrystallization and whisker rotation.

  3. Behaviour of laser metal deposited Ti6Al4V/ Cu composites in Hank’s solution in terms of biocompatibility properties

    CSIR Research Space (South Africa)

    Erinosho, MF

    2016-01-01

    Full Text Available Ti6Al4V alloy is a well-known material for biomedical application due to the very excellent corrosion resistance it possessed. Cu has an excellent antimicrobial property and stabilizes the immune system of the body activities. In this present study...

  4. Fit of cast commercially pure titanium and Ti-6Al-4V alloy crowns before and after marginal refinement by electrical discharge machining.

    Science.gov (United States)

    Contreras, Edwin Fernando Ruiz; Henriques, Guilherme Elias Pessanha; Giolo, Suely Ruiz; Nobilo, Mauro Antonio Arruda

    2002-11-01

    Titanium has been suggested as a replacement for alloys currently used in single-tooth restorations and fixed partial dentures. However, difficulties in casting have resulted in incomplete margins and discrepancies in marginal fit. This study evaluated and compared the marginal fit of crowns fabricated from a commercially pure titanium (CP Ti) and from Ti-6Al-4V alloy with crowns fabricated from a Pd-Ag alloy that served as a control. Evaluations were performed before and after marginal refinement by electrical discharge machining (EDM). Forty-five bovine teeth were prepared to receive complete cast crowns. Stone and copper-plated dies were obtained from impressions. Fifteen crowns were cast with each alloy (CP Ti, Ti-6Al-4V, and Pd-Ag). Marginal fit measurements (in micrometers) were recorded at 4 reference points on each casting with a traveling microscope. Marginal refinement with EDM was conducted on the titanium-based crowns, and measurements were repeated. Data were analyzed with the Kruskal-Wallis test, paired t test, and independent t test at a 1% probability level. The Kruskal-Wallis test showed significant differences among mean values of marginal fit for the as-cast CP Ti crowns (mean [SD], 83.9 [26.1] microm) and the other groups: Ti-6Al-4V (50.8 [17.2] microm) and Pd-Ag (45.2 [10.4] microm). After EDM marginal refinement, significant differences were detected among the Ti-6Al-4V crowns (24.5 [10.9] microm) and the other 2 groups: CP Ti (50.6 [20.0] microm) and Pd-Ag (not modified by EDM). Paired t test results indicated that marginal refinement with EDM effectively improved the fit of CP Ti crowns (from 83.9 to 50.6 microm) and Ti-6Al-4V crowns (from 50.8 to 24.5 microm). However, the difference in improvement between the two groups was not significant by t test. Within the limitations of this study, despite the superior results for Ti-6Al-4V, both groups of titanium-based crowns had clinically acceptable marginal fits. After EDM marginal refinement

  5. Are new TiNbZr alloys potential substitutes of the Ti6Al4V alloy for dental applications? An electrochemical corrosion study.

    Science.gov (United States)

    Ribeiro, Ana Lúcia Roselino; Hammer, Peter; Vaz, Luís Geraldo; Rocha, Luís Augusto

    2013-12-01

    The main aim of this work was to assess the electrochemical behavior of new Ti35Nb5Zr and Ti35Nb10Zr alloys in artificial saliva at 37 °C to verify if they are indicated to be used as biomaterials in dentistry as alternatives to Ti6Al4V alloys in terms of corrosion protection efficiency of the material. Electrochemical impedance spectroscopy (EIS) experiments were carried out for different periods of time (0.5-216 h) in a three-electrode cell, where the working electrode (Ti alloys) was exposed to artificial saliva at 37 °C. The near-surface region of the alloys was investigated using x-ray photoelectron spectroscopy (XPS). All alloys exhibited an increase in corrosion potential with the immersion time, indicating the growth and stabilization of the passive film. Ti35Nb5Zr and Ti6Al4V alloys had their EIS results interpreted by a double-layer circuit, while the Ti35Nb10Zr alloy was modeled by a one-layer circuit. In general, the new TiNbZr alloys showed similar behavior to that observed for the Ti6Al4V. XPS results suggest, in the case of the TiNbZr alloys, the presence of a thicker passive layer containing a lower fraction of TiO2 phase than that of Ti6Al4V. After long-term immersion, all alloys develop a calcium phosphate phase on the surface. The new TiNbZr alloys appear as potential candidates to be used as a substitute to Ti6Al4V in the manufacturing of dental implant-abutment sets.

  6. Preparation of conversion coating on Ti-6Al-4V alloy in mixed solution of phytic acid and ammonium fluoride through chemical modification

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lanlan; He, Jian; Yang, Xu, E-mail: 13629752655@163.com

    2016-05-15

    Highlights: • A conversion coating was prepared on Ti-6Al-4V alloy by chemical treatment. • The formation of conversion coating is the result of combined action of phytic acid and NH{sub 4}F. • The pH value of mixed solution plays a critical role in the formation process of conversion coating. - Abstract: Conversion coatings on Ti-6Al-4V alloy was prepared through chemical modification in phytic acid and ammonium fluoride mixed solution. The influences of pH, time and the composition of solution on the microstructure of alloy surface were investigated. Scanning electron microscopy was used to observe the microstructure. The chemical composition of alloy surface before and after modification was investigated by energy dispersive X-ray spectroscopy. The results indicated that a conversion coating could be formed on the Ti-6Al-4V alloy in a mixed solution of phytic acid and ammonium fluoride, the growth and microstructure of the conversion coatings were critically dependent on the pH, time and concentration of phytic acid and ammonium fluoride. In 100 mg/ml phytic acid containing 125 mg/ml ammonium fluoride solution with a pH of 6, a compact conversion coating with the thickness of about 4.7 μm formed after 30 min immersion on Ti-6Al-4V alloy surface. The preliminary evaluation of bioactivity of conversion coating was performed by in vitro cell experiments. The results showed that this chemical modification method is a promising surface modification technique for Ti-6Al-4V alloy inplants.

  7. Effect of HAp and β-TCP incorporation on the tribological response of Ti6Al4V biocomposites for implant parts.

    Science.gov (United States)

    Dantas, T A; Costa, M M; Miranda, G; Silva, F S; Abreu, C S; Gomes, J R

    2018-04-01

    Titanium and its alloys have been widely used in many engineering areas due to their properties. Despite having a high implant-tissue osseointegration time, Ti6Al4V has been extensively used in prosthesis and articular implants. To promote a faster bone ingrowth and consequently reduce the implant fixation time, the addition of a bioactive phase to form a biocomposite seems to be an excellent solution. Because of their bioactivity and similarity in composition with the human bone, HAp and β-TCP are two of the most widely used calcium phosphates in biomedical applications. To guarantee a strong adhesion of the previous bioactive materials in the implants surface, samples of Ti6Al4V, Ti6Al4V+HAp (10 vol %) and Ti6Al4V+β-TCP (10 vol %) TCP were processed by the hot pressing technique. Tribological tests against Al 2 O 3, lubricated in PBS at 37°C were carried out on a ball-on-flat reciprocating sliding geometry. Loads in the range of 3 N to 30 N were applied and their effect on the friction behavior and wear resistance of the tested materials was evaluated. Values of the coefficient of friction as well as the wear rate tend to increase with the addition of a bioactive phase to the Ti alloy. Micrographs of the worn surfaces showed that abrasion and plastic deformation are the prevailing wear mechanisms in the studied tribosystems. For biocomposites, particularly in the case of Ti6Al4V+HAp, pull-out of bioactive particle clusters has a determinant role on the tribological response, increasing both the friction coefficient and the specific wear rate. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1010-1016, 2018. © 2017 Wiley Periodicals, Inc.

  8. Influence of thermal oxidation duration on the microstructure and fretting wear behavior of Ti6Al4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Song [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Liao, Zhenhua [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Liu, Yuhong [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Liu, Weiqiang, E-mail: weiqliu@hotmail.com [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China)

    2015-06-01

    Thermal oxidation under water oxidizing atmosphere was performed on Ti6Al4V alloy under different durations from 2 h to 8 h. Surface characterizations were performed using X-ray diffractometery (XRD), scanning electron microscopy (SEM), Raman spectroscopy, nanoindentation and nano scratch testing. Fretting wear behaviors of untreated and oxidized samples were also examined. The formed oxide coating mainly included rutile TiO{sub 2} as well as a little alumina. The weight gain with respect to the oxidation duration obeyed the linear oxidation kinetics law. The growth of oxide grains was in inadequate growth state of incomplete scale coverage from 2nd to 4th hour duration, in normal growth state from 4th to 6th hour duration while in excessive growth state of oxide particle agglomeration and surface roughening from 6th to 8th (or more than 8th) hour duration. The coating thickness increased from 5 μm to 12 μm as oxidation duration increased from 2 h to 8 h. The increase in duration also increased surface roughness and nano hardness as well as adhesion strength of the film/substrate for oxidized samples. The nano hardness value was 10.06 ± 2.15 GPa and the critical load of failure during nano scratch testing was 554.3 ± 6.44 mN for 4 h treated sample. The untreated and oxidized samples showed a same fretting running status and fretting regime with a displacement amplitude of 200 μm while revealing different fretting failure mechanisms. It was mainly abrasive and adhesive wear under ploughing force for untreated sample, while a mix of 3-body abrasion by rolling oxide particles and severe plastic deformation under high contact stress between two ceramic materials for the oxidized samples. The oxide coating was not worn out and improved the fretting wear resistance of titanium alloy. - Highlights: • A thickness of 5–12 μm rutile TiO{sub 2} coating formed under different oxidation durations. • Weight gain with respect to oxidation duration obeyed linear

  9. Thermal Modeling and Simulation of Electron Beam Melting for Rapid Prototyping on Ti6Al4V Alloys

    Science.gov (United States)

    Neira Arce, Alderson

    To be a viable solution for contemporary engineering challenges, the use of titanium alloys in a wider range of applications requires the development of new techniques and processes that are able to decrease production cost and delivery times. As a result, the use of material consolidation in a near-net-shape fashion, using dynamic techniques like additive manufacturing by electron beam selective melting EBSM represents a promising method for part manufacturing. However, a new product material development can be cost prohibitive, requiring the use of computer modeling and simulation as a way to decrease turnaround time. To ensure a proper representation of the EBSM process, a thermophysical material characterization and comparison was first performed on two Ti6Al4V powder feedstock materials prepared by plasma (PREP) and gas atomized (GA) processes. This evaluation comprises an evaluation on particle size distribution, density and powder surface area, collectively with the temperature dependence on properties such as heat capacity, thermal diffusivity, thermal conductivity and surface emissivity. Multiple techniques were employed in this evaluation, including high temperature differential scanning calorimetry (HT-DSC), laser flash analysis (LFA), infrared remote temperature analysis (IR-Thermography), laser diffraction, liquid and gas pycnometry using mercury and krypton adsorption respectively. This study was followed by the review of complementary strategies to simulate the temperature evolution during the EBSM process, using a finite element analysis package called COMSOL Multiphysics. Two alternatives dedicated to representing a moving heat source (electron beam) and the powder bed were developed using a step-by-step approximation initiative. The first method consisted of the depiction of a powder bed discretized on an array of domains, each one representing a static melt pool, where the moving heat source was illustrated by a series of time dependant selective

  10. The effect of impurities elements on titanium alloy (Ti-6Al-4V) MIM sintered part properties

    Science.gov (United States)

    Ahmad, M. Azmirruddin; Jabir, M.; Johari, N.; Ibrahim, R.; Hamidi, N.

    2017-12-01

    The titanium alloys (Ti-6Al-4V) compact were fabricated by Metal Injection Molding (MIM). However, the real challenge of MIM processing for titanium alloy is its affinity to be contaminated by interstitial light elements such as oxygen and carbon which could degrade the mechanical properties of sintered titanium alloy such as its tensile strength and ductility. The sintering temperature effect on carbon and oxygen content that affects its physical and mechanical properties of the sintered titanium alloy was studied. The titanium MIM brown specimen was sintered at four different sintering temperatures which are 1100 °C, 1150 °C, 1200 °C and 1250 °C for 4 hours under furnace control atmosphere. The experimental result indicated that the specimen which has been made from 100% gas atomized powder have a relative density of 92.2 % - 97.6 %, the range of porosity percent around 2.38 %-3.84 %. Ultimate tensile strength of 873.11 MPa - 1007.19 MPa and ductility percent in range of 1.89 %-3.46 %. The titanium alloy MIM specimen which was sintered at 1150 °C contained 0.145 % of carbon and 0.143 % of oxygen possess the highest value of density and tensile strength, with value of 4.344 gcm-3 and 1007.2 MPa respectively. Meanwhile, the titanium alloy MIM specimen which was sintered at 1200 °C contains 0.130 % of carbon and 0.127 % of oxygen, has the highest percentage of ductility with 3.46 %. The carbon content level increased as the sintering temperature increased due to decomposition of high molecule weight of residue binder system which could not be eliminated during solvent extraction debinding process and sintered at low temperature. Contrarily, the oxygen content level indicates a decrease as the sintering temperature increased. Briefly, the sintering temperature could influence the physical and mechanical properties of titanium alloy MIM sintered specimen as it influences the oxygen and carbon content level in the alloys.

  11. Electrochemical assessment of some titanium and stainless steel impact dental alloys

    International Nuclear Information System (INIS)

    Echavarria, A.; Arroyave, C.

    2003-01-01

    Commercially pure titanium alloy, Ti-6Al-4V alloy and stainless steel screw implants were evaluated in both Ringer and synthetic saliva physiological solutions at body temperature by EIS (Electrochemical Impedance Spectroscopy) with immersion times of 30 d. Results were simulated as a sandwich system composed by four capacitors-resistances connected in series with the solution resistance. A model explaining the results in terms of the porosity and thickness of four different layers, was proposed. (Author) 22 refs

  12. Synthesis and characterization of MoS2/Ti composite coatings on Ti6Al4V prepared by laser cladding

    Directory of Open Access Journals (Sweden)

    Rongjuan Yang

    2013-02-01

    Full Text Available The MoS2/Ti composite coating with sub-micron grade structure has been prepared on Ti6Al4V by laser method under argon protection. The morphology, microstructure, microhardness and friction coefficient of the coating were examined. The results indicated that the molybdenum disulfide was decomposed during melting and resolidification. The phase organization of composite coating mainly consisted of ternary element sulfides, molybdenum sulfides and titanium sulfides. The friction coefficient of and the surface roughness the MoS2/Ti coating were lower than those of Ti6Al4V. The composite coating exhibits excellent adhesion to the substrates, less surface roughness, good wear resistance and harder surface.

  13. SCC of Ti-6Al-4V foil by methanol - Effect of treatments with 2,4-pentanedione and its metal complexes.

    Science.gov (United States)

    Haney, E. G.; Fugassi, P.

    1972-01-01

    The susceptibility of Ti-6Al-4V foil to stress corrosion cracking (SCC) by methanol can be decreased by treatment of the foil with 2,4-pentanedione prior to its immersion in the corroding media. It is assumed that such treatments remove from the protective film formed on the foil by exposure to the atmosphere, certain metal ions whose oxides are more readily penetrated by the ions, Na + and Cl- or Fe(3+) and Cl-, present in the corroding media.

  14. Influence of the final temperature of investment healting on the tensile strength and Vickers hardness of CP Ti and Ti-6Al-4V alloy

    Directory of Open Access Journals (Sweden)

    Pedro César Garcia Oliveira

    2007-02-01

    Full Text Available The aim of the work was to evaluate the influence of the temperature of investment healting on the tensile strength and Vickers hardness of CP Ti and Ti-6Al-4V alloy casting. Were obtained for the tensile strength test dumbbell rods that were invested in the Rematitan Plus investment and casting in the Discovery machine cast. Thirty specimens were obtained, fiftten to the CP Titanium and fifteen to the Ti-6Al-4V alloy, five samples to each an of the three temperatures of investment: 430ºC (control group, 480ºC and 530ºC. The tensile test was measured by means of a universal testing machine, MTS model 810, at a strain of 1.0 mm/min. After the tensile strenght test the specimens were secctioned, embedded and polished to hardness measurements, using a Vickers tester, Micromet 2100. The means values to tensile tests to the temperatures 430ºC, 480 and 530: CP Ti (486.1 - 501.16 - 498.14 -mean 495.30 MPa and Ti-6Al-4V alloy (961.33 - 958.26 - 1005.80 - mean 975.13 MPa while for the Vickers hardness the values were (198.06, 197.85, 202.58 - mean 199.50 and (352.95, 339.36, 344.76 - mean 345.69, respectively. The values were submitted to Analysis of Variance (ANOVA and Tukey,s Test that indicate differences significant only between the materials, but not between the temperature, for both the materias. It was conclued that increase of the temperature of investment its not chance the tensile strength and the Vickers hardness of the CP Titanium and Ti-6Al-4V alloy.

  15. Characterization and diffusion model for the titanium boride layers formed on the Ti6Al4V alloy by plasma paste boriding

    Energy Technology Data Exchange (ETDEWEB)

    Keddam, Mourad, E-mail: keddam@yahoo.fr [Laboratoire de Technologie des Matériaux, Faculté de Génie Mécanique et Génie des Procédés, USTHB, B.P. No. 32, 16111 El-Alia, Bab-Ezzouar, Algiers (Algeria); Taktak, Sukru [Metallurgical and Materials Engineering, Faculty of Technology, Afyon Kocatepe University, ANS Campus, 03200, Afyonkarahisar (Turkey)

    2017-03-31

    Highlights: • Titanium boride layers were produced by plasma paste boriding on Ti6Al4V at 973–1073 K. • Formation rates of the Ti boride layers have parabolic character at all temperatures. • Boron diffusivities were estimated using a diffusion model including incubation times. • Activation energies of boron in TiB{sub 2} and TiB were 136 and 63 kJ/mol respectively. - Abstract: The present study is focused on the estimation of activation energy of boron in the plasma paste borided Ti6Al4V alloy, which is extensively used in technological applications, using an analytical diffusion model. Titanium boride layers were successfully produced by plasma paste boriding method on the Ti6Al4V alloy in the temperature range of 973–1073 K for a treatment time ranging from 3 to 7 h. The presence of both TiB{sub 2} top-layer and TiB whiskers sub-layer was confirmed by the XRD analysis and SEM observations. The surface hardness of the borided alloy was evaluated using Micro-Knoop indenter. The formation rates of the TiB{sub 2} and TiB layers were found to have a parabolic character at all applied process temperatures. A diffusion model was suggested to estimate the boron diffusivities in TiB{sub 2} and TiB layers under certain assumptions, by considering the effect of boride incubation times. Basing on own experimental data on boriding kinetics, the activation energies of boron in TiB{sub 2} and TiB phases were estimated as 136.24 ± 0.5 and 63.76 ± 0.5 kJ mol{sup −1}, respectively. Finally, the obtained values of boron activation energies for Ti6Al4V alloy were compared with the data available in the literature.

  16. Experimental characterization of nanoparticles emissions during Laser Shock Processing of AA6061, AISI304 and Ti6Al4V

    Directory of Open Access Journals (Sweden)

    João F. Gomes

    2017-11-01

    Full Text Available This paper describes an experimental study on the emission of nanometric size particles during laser shock processing of metallic materials: stainless steel, aluminum and titanium alloys which are the most common ones processed by this technique. The emission of nanometric size particles was confirmed to consist of aggregates composed of smaller spherical particles in the range of 10-20 nm, covered by a small concentric “layer” probably of metal oxides. The analysis of the nanoparticles showed the presence of the main elements present in the tested alloys as well as high oxygen content, which is another indication of the presence of oxides of Fe, Al and Ti. The amount of emitted nanoparticles, showed considerable increases over the baseline measured for the working environment, and these increases correspond to the more intense pulses of the laser beam. The material density was seen to highly affect the quantity of emitted nanoparticles. During LSP of aluminium alloy (the lighter material a large quantity of nanoparticles was measured, while in LSP of stainless steel few nanoparticles were observed, and this is the denser material, among the three tested. Titanium alloy results in intermediate values. The study of these emissions is innovative and relevant for industrial environments where the manufacturing process is in use.

  17. Effect of argon purity on mechanical properties, microstructure and fracture mode of commercially pure (cp) Ti and Ti-6Al-4V alloys for ceramometal dental prostheses

    International Nuclear Information System (INIS)

    Bauer, Jose; Cella, Suelen; Pinto, Marcelo M; Filho, Leonardo E Rodrigues; Reis, Alessandra; Loguercio, Alessandro D

    2009-01-01

    Provision of an inert gas atmosphere with high-purity argon gas is recommended for preventing titanium castings from contamination although the effects of the level of argon purity on the mechanical properties and the clinical performance of Ti castings have not yet been investigated. The purpose of this study was to evaluate the effect of argon purity on the mechanical properties and microstructure of commercially pure (cp) Ti and Ti-6Al-4V alloys. The castings were made using either high-purity and/or industrial argon gas. The ultimate tensile strength (UTS), proportional limit (PL), elongation (EL) and microhardness (VHN) at different depths were evaluated. The microstructure of the alloys was also revealed and the fracture mode was analyzed by scanning electron microscopy. The data from the mechanical tests and hardness were subjected to a two-and three-way ANOVA and Tukey's test (α = 0.05). The mean values of mechanical properties were not affected by the argon gas purity. Higher UTS, PL and VHN, and lower EL were observed for Ti-6Al-4V. The microhardness was not influenced by the argon gas purity. The industrial argon gas can be used to cast cp Ti and Ti-6Al-4V.

  18. Experimental investigation with respect to the performance of deep submillimeter-scaled textured tools in dry turning titanium alloy Ti-6Al-4V

    Science.gov (United States)

    Li, Ning; Chen, Yongjie; Kong, Dongdong; Tan, Shenglin

    2017-05-01

    Titanium alloy Ti-6Al-4V falls under the category of the most difficult to machine materials due to its inherent high strength maintained at elevated temperature and low thermal conductivity. Based on size effect, the poor machinability may be improved by surface texturing on the tools. Thus, the effect of deep submillimeter-scaled textures on the cutting performance in Ti-6Al-4V turning was investigated. To this end, three kinds of surface textures with different sizes were fabricated using femtosecond laser on rake faces of the uncoated cemented carbide (WC/Co) inserts. Then, dry cutting experiments were conducted with these textured inserts and conventional inserts under the condition of cutting speed Vc = 50m/min, depth of cut ap = 2 mm, and feed rate f = 0.3 mm/rev. The cutting performance is evaluated in terms of cutting forces, coefficient of friction at the tool-chip interface. Results obtained in this work show the feasibility of fabricating deep submillimeter-scaled textures on tool rake face to improve the machinability of Ti-6Al-4V. The parallel type of textured tool P01 demonstrates the best performance in both reducing cutting force and improving the friction properties on the rake face. This result can be explained by the reduced tool-chip contact area and the ploughing effect.

  19. Drilling High Precision Holes in Ti6Al4V Using Rotary Ultrasonic Machining and Uncertainties Underlying Cutting Force, Tool Wear, and Production Inaccuracies.

    Science.gov (United States)

    Chowdhury, M A K; Sharif Ullah, A M M; Anwar, Saqib

    2017-09-12

    Ti6Al4V alloys are difficult-to-cut materials that have extensive applications in the automotive and aerospace industry. A great deal of effort has been made to develop and improve the machining operations of Ti6Al4V alloys. This paper presents an experimental study that systematically analyzes the effects of the machining conditions (ultrasonic power, feed rate, spindle speed, and tool diameter) on the performance parameters (cutting force, tool wear, overcut error, and cylindricity error), while drilling high precision holes on the workpiece made of Ti6Al4V alloys using rotary ultrasonic machining (RUM). Numerical results were obtained by conducting experiments following the design of an experiment procedure. The effects of the machining conditions on each performance parameter have been determined by constructing a set of possibility distributions (i.e., trapezoidal fuzzy numbers) from the experimental data. A possibility distribution is a probability-distribution-neural representation of uncertainty, and is effective in quantifying the uncertainty underlying physical quantities when there is a limited number of data points which is the case here. Lastly, the optimal machining conditions have been identified using these possibility distributions.

  20. Micro-CT-based improvement of geometrical and mechanical controllability of selective laser melted Ti6Al4V porous structures

    Energy Technology Data Exchange (ETDEWEB)

    Van Bael, S., E-mail: Simon.Vanbael@mech.kuleuven.be [Department of Mechanical Engineering, Division of Production Engineering, Machine Design and Automation, Katholieke Universiteit Leuven, Celestijnenlaan 300B, B-3001 Leuven (Belgium); Department of Mechanical Engineering, Division of Biomechanics and Engineering Design, Katholieke Universiteit Leuven, Celestijnenlaan 300C, B-3001 Leuven (Belgium); Prometheus, Division of Skeletal Tissue Engineering, Katholieke Universiteit Leuven, O and N 1, Minderbroedersstraat 8A, B-3000 Leuven (Belgium); Kerckhofs, G., E-mail: Greet.Kerckhofs@mtm.kuleuven.be [Department of Metallurgy and Materials Engineering, Katholieke Universiteit Leuven, Kasteelpark Arenberg 44, B-3001 Leuven (Belgium); Prometheus, Division of Skeletal Tissue Engineering, Katholieke Universiteit Leuven, O and N 1, Minderbroedersstraat 8A, B-3000 Leuven (Belgium); Moesen, M., E-mail: Maarten.Moesen@mtm.kuleuven.be [Department of Metallurgy and Materials Engineering, Katholieke Universiteit Leuven, Kasteelpark Arenberg 44, B-3001 Leuven (Belgium); Prometheus, Division of Skeletal Tissue Engineering, Katholieke Universiteit Leuven, O and N 1, Minderbroedersstraat 8A, B-3000 Leuven (Belgium); Pyka, G., E-mail: Gregory.Pyka@mtm.kuleuven.be [Department of Metallurgy and Materials Engineering, Katholieke Universiteit Leuven, Kasteelpark Arenberg 44, B-3001 Leuven (Belgium); Prometheus, Division of Skeletal Tissue Engineering, Katholieke Universiteit Leuven, O and N 1, Minderbroedersstraat 8A, B-3000 Leuven (Belgium); Schrooten, J., E-mail: Jan.Schrooten@mtm.kuleuven.be [Department of Metallurgy and Materials Engineering, Katholieke Universiteit Leuven, Kasteelpark Arenberg 44, B-3001 Leuven (Belgium); Prometheus, Division of Skeletal Tissue Engineering, Katholieke Universiteit Leuven, O and N 1, Minderbroedersstraat 8A, B-3000 Leuven (Belgium); and others

    2011-09-15

    Highlights: {yields} Selective laser melting as a production tool for porous Ti6Al4V structures. {yields} Significant mismatch between designed and as-produced properties. {yields} Decreasing mismatch using a micro-CT-based protocol. {yields} Mismatch of pore size decreased from 45% to 5%. {yields} Increased morphological controllability increases mechanical controllability. - Abstract: Despite the fact that additive manufacturing (AM) techniques allow to manufacture complex porous parts with a controlled architecture, differences can occur between designed and as-produced morphological properties. Therefore this study aimed at optimizing the robustness and controllability of the production of porous Ti6Al4V structures using selective laser melting (SLM) by reducing the mismatch between designed and as-produced morphological and mechanical properties in two runs. In the first run, porous Ti6Al4V structures with different pore sizes were designed, manufactured by SLM, analyzed by microfocus X-ray computed tomography (micro-CT) image analysis and compared to the original design. The comparison was based on the following morphological parameters: pore size, strut thickness, porosity, surface area and structure volume. Integration of the mismatch between designed and measured properties into a second run enabled a decrease of the mismatch. For example, for the average pore size the mismatch decreased from 45% to 5%. The demonstrated protocol is furthermore applicable to other 3D structures, properties and production techniques, powder metallurgy, titanium alloys, porous materials, mechanical characterization, tomography.

  1. The black and white coatings on Ti-6Al-4V alloy or pure titanium by plasma electrolytic oxidation in concentrated silicate electrolyte

    Science.gov (United States)

    Han, Jun-xiang; Cheng, Yu-lin; Tu, Wen-bin; Zhan, Ting-Yan; Cheng, Ying-liang

    2018-01-01

    Black TiO2 has triggered scientific interest due to its unique properties such as enhanced solar-driven photocatalytic activity. In this paper, plasma electrolytic oxidation (PEO) treatment of Ti-6Al-4V alloy has been carried out in concentrated sodium silicate electrolyte. Silica-based black and white TiO2 coatings respectively have been obtained by controlling the oxidation time. The black coating, which was formed with a short treatment time, shows good corrosion resistance and the black appearance can be attributed to the presence of Ti2+ and Ti3+ in the coating. The lower valence titanium ions are absent in the white coatings and they also contain relatively higher Na content compared to the black coatings. The white coatings have great surface roughnesses and super hydrophilicity. The bonding strengths of the black and white coatings on the Ti-6Al-4V alloy are ∼14.4 and 4.3 MPa, respectively. The vanadium contributes little to the black appearance of the coating on Ti6Al4V alloy, since the same phenomena occur for the PEO of a pure titanium substrate.

  2. Corrosion resistance characteristics of a Ti-6Al-4V alloy scaffold that is fabricated by electron beam melting and selective laser melting for implantation in vivo.

    Science.gov (United States)

    Zhao, Bingjing; Wang, Hong; Qiao, Ning; Wang, Chao; Hu, Min

    2017-01-01

    The purpose of this study is to determine the corrosion resistance of Ti-6Al-4V alloy fabricated with electron beam melting and selective laser melting for implantation in vivo. Ti-6Al-4V alloy specimens were fabricated with electron beam melting (EBM) and selective laser melting (SLM). A wrought form of Ti-6Al-4V alloy was used as a control. Surface morphology observation, component analysis, corrosion resistance experimental results, electrochemical impedance spectroscopy, crevice corrosion resistance experimental results, immersion test and metal ions precipitation analysis were processed, respectively. The thermal stability of EBM specimen was the worst, based on the result of open circuit potential (OCP) result. The result of electrochemical impedance spectroscopy indicated that the corrosion resistance of the SLM specimen was the best under the low electric potential. The result of potentiodynamic polarization suggested that the corrosion resistance of the SLM specimen was the best under the low electric potential (1.5V).The crevice corrosion resistance of the EBM specimen was the best. The corrosion resistance of SLM specimen was the best, based on the result of immersion test. The content of Ti, Al and V ions of EBM, SLM and wrought specimens was very low. In general, the scaffolds that were fabricated with EBM and SLM had good corrosion resistance, and were suitable for implantation in vivo. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Effect of argon purity on mechanical properties, microstructure and fracture mode of commercially pure (cp) Ti and Ti-6Al-4V alloys for ceramometal dental prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Jose [Department of Dentistry I, School of Dentistry, University Federal of Maranhao, Campus Universitario do Bacanga, Av. dos Portugueses, s/n, 65085680, Sao Luis/MA (Brazil); Cella, Suelen; Pinto, Marcelo M; Filho, Leonardo E Rodrigues [Department of Dental Materials, School of Dentistry, University of Sao Paulo, Av. Prof. Lineu Prestes, 2227, 05508-900, Sao Paulo/SP (Brazil); Reis, Alessandra; Loguercio, Alessandro D, E-mail: jrob@usp.b [Department of Restorative Dentistry, Universidade Estadual de Ponta Grossa Av. General Carlos Cavalcanti, 4748, Bloco M, Sala 64 A, 84030-900, Ponta Grossa/PR (Brazil)

    2009-12-15

    Provision of an inert gas atmosphere with high-purity argon gas is recommended for preventing titanium castings from contamination although the effects of the level of argon purity on the mechanical properties and the clinical performance of Ti castings have not yet been investigated. The purpose of this study was to evaluate the effect of argon purity on the mechanical properties and microstructure of commercially pure (cp) Ti and Ti-6Al-4V alloys. The castings were made using either high-purity and/or industrial argon gas. The ultimate tensile strength (UTS), proportional limit (PL), elongation (EL) and microhardness (VHN) at different depths were evaluated. The microstructure of the alloys was also revealed and the fracture mode was analyzed by scanning electron microscopy. The data from the mechanical tests and hardness were subjected to a two-and three-way ANOVA and Tukey's test (alpha = 0.05). The mean values of mechanical properties were not affected by the argon gas purity. Higher UTS, PL and VHN, and lower EL were observed for Ti-6Al-4V. The microhardness was not influenced by the argon gas purity. The industrial argon gas can be used to cast cp Ti and Ti-6Al-4V.

  4. SCC and Corrosion Fatigue characterization of a Ti-6Al-4V alloy in a corrosive environment – experiments and numerical models

    Directory of Open Access Journals (Sweden)

    S. Baragetti

    2014-10-01

    Full Text Available In the present article, a review of the complete characterization in different aggressive media of a Ti-6Al-4V titanium alloy, performed by the Structural Mechanics Laboratory of the University of Bergamo, is presented. The light alloy has been investigated in terms of corrosion fatigue, by axial fatigue testing (R = 0.1 of smooth and notched flat dogbone specimens in laboratory air, 3.5% wt. NaCl–water mixture and methanol–water mixture at different concentrations. The first corrosive medium reproduced a marine environment, while the latter was used as a reference aggressive environment. Results showed that a certain corrosion fatigue resistance is found in a salt water medium, while the methanol environment caused a significant drop – from 23% to 55% in terms of limiting stress reduction – of the fatigue resistance of the Ti-6Al-4V alloy, even for a solution containing 5% of methanol. A Stress Corrosion Cracking (SCC experimental campaign at different methanol concentrations has been conducted over slightly notched dog-bone specimens (Kt = 1.18, to characterize the corrosion resistance of the alloy under quasi-static load conditions. Finally, crack propagation models have been implemented to predict the crack propagation rates for smooth specimens, by using Paris, Walker and Kato-Deng-Inoue-Takatsu propagation formulae. The different outcomes from the forecasting numerical models were compared with experimental results, proposing modeling procedures for the numerical simulation of fatigue behavior of a Ti-6Al-4V alloy.

  5. Corrosion Behavior of Surface-Treated Implant Ti-6Al-4V by Electrochemical Polarization and Impedance Studies

    Science.gov (United States)

    Paul, Subir; Yadav, Kasturi

    2011-04-01

    Implant materials for orthopedic and heart surgical services demand a better corrosion resistance material than the presently used titanium alloys, where protective oxide layer breaks down on a prolonged stay in aqueous physiological human body, giving rise to localized corrosion of pitting, crevice, and fretting corrosion. A few surface treatments on Ti alloy, in the form of anodization, passivation, and thermal oxidation, followed by soaking in Hank solution have been found to be very effective in bringing down the corrosion rate as well as producing high corrosion resistance surface film as reflected from electrochemical polarization, cyclic polarization, and Electrochemical Impedance Spectroscopy (EIS) studies. The XRD study revealed the presence of various types of oxides along with anatase and rutile on the surface, giving rise to high corrosion resistance film. While surface treatment of passivation and thermal oxidation could reduce the corrosion rate by 1/5th, anodization in 0.3 M phosphoric acid at 16 V versus stainless steel cathode drastically brought down the corrosion rate by less than ten times. The mechanism of corrosion behavior and formation of different surface films is better understood from the determination of EIS parameters derived from the best-fit equivalent circuit.

  6. Electrochemical behaviour of laser-clad Ti6Al4V with CP Ti in 0.1 M oxalic acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Obadele, Babatunde Abiodun, E-mail: obadele4@gmail.com [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Olubambi, Peter A. [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Andrews, Anthony [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of Materials Engineering, Kwame Nkrumah University of Science and Technology, Kumasi (Ghana); Pityana, Sisa [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); National Laser Center, Council for Scientific and Industrial Research, Pretoria (South Africa); Mathew, Mathew T. [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612 (United States)

    2015-10-15

    The relationship between the microstructure and corrosion behaviour of Ti6Al4V alloy and laser-clad commercially pure (CP) Ti coating was investigated. The microstructure, phases and properties of the clad layers were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Electrochemical measurement techniques including open circuit potential (OCP) and potentiodynamic polarisation were used to evaluate the corrosion behaviour of Ti6Al4V alloy in 0.1 M oxalic acid solution and the results compared to the behaviour of laser-clad CP Ti at varying laser scan speed. Results showed that laser-clad CP Ti at scan speed of 0.4 m/min formed a good cladding layer without defects such as cracks and pores. The phase present in the cladding layer was mostly α′-Ti. The microstructures of the clad layer were needle like acicular/widmanstätten α. An improvement in the microhardness values was also recorded. Although the corrosion potentials of the laser-clad samples were less noble than Ti6Al4V alloy, the polarisation measurement showed that the anodic current density was lower and also increases with increasing laser scanning speed. - Highlights: • The microstructure and corrosion behaviour of laser-clad CP Ti was investigated. • Laser-clad CP Ti 0.4 m/min scan speed gave a good coating without cracks and pores. • The phase present in the clad layer was mostly α′-Ti. • An improvement in the microhardness values was also recorded. • Anodic current density for coatings increases with increasing laser scan speed.

  7. On the development of a dual-layered diamond-coated tool for the effective machining of titanium Ti-6Al-4V alloy

    Science.gov (United States)

    Srinivasan, Balaji; Ramachandra Rao, M. S.; Rao, Balkrishna C.

    2017-01-01

    This work is focused on the development of a dual-layered diamond-coated tungsten carbide tool for machining titanium Ti-6Al-4V alloy. A hot-filament chemical vapor deposition technique was used to synthesize diamond films on tungsten carbide tools. A boron-doped diamond interlayer was added to a microcrystalline diamond layer in an attempt to improve the interface adhesion strength. The dual-layered diamond-coated tool was employed in machining at cutting speeds in the range of 70 to 150 m min-1 with a lower feed and a lower depth of cut of 0.5 mm rev-1 and 0.5 mm, respectively, to operate in the transition from adhesion- to diffusion-tool-wear and thereby arrive at suitable conditions for enhancing tool life. The proposed tool was then compared, on the basis of performance under real-time cutting conditions, with commercially available microcrystalline diamond, nanocrystalline diamond, titanium nitride and uncoated tungsten carbide tools. The life and surface finish of the proposed dual-layered tool and uncoated tungsten carbide were also investigated in interrupted cutting such as milling. The results of this study show a significant improvement in tool life and finish of Ti-6Al-4V parts machined with the dual-layered diamond-coated tool when compared with its uncoated counterpart. These results pave the way for the use of a low-cost tool, with respect to, polycrystalline diamond for enhancing both tool life and machining productivity in critical sectors fabricating parts out of titanium Ti-6Al-4V alloy. The application of this coating technology can also be extended to the machining of non-ferrous alloys owing to its better adhesion strength.

  8. Evaluation of biological properties of electron beam melted Ti6Al4V implant with biomimetic coating in vitro and in vivo.

    Directory of Open Access Journals (Sweden)

    Xiang Li

    Full Text Available BACKGROUND: High strength porous titanium implants are widely used for the reconstruction of craniofacial defects because of their similar mechanical properties to those of bone. The recent introduction of electron beam melting (EBM technique allows a direct digitally enabled fabrication of patient specific porous titanium implants, whereas both their in vitro and in vivo biological performance need further investigation. METHODS: In the present study, we fabricated porous Ti6Al4V implants with controlled porous structure by EBM process, analyzed their mechanical properties, and conducted the surface modification with biomimetic approach. The bioactivities of EBM porous titanium in vitro and in vivo were evaluated between implants with and without biomimetic apatite coating. RESULTS: The physical property of the porous implants, containing the compressive strength being 163 - 286 MPa and the Young's modulus being 14.5-38.5 GPa, is similar to cortical bone. The in vitro culture of osteoblasts on the porous Ti6Al4V implants has shown a favorable circumstance for cell attachment and proliferation as well as cell morphology and spreading, which were comparable with the implants coating with bone-like apatite. In vivo, histological analysis has obtained a rapid ingrowth of bone tissue from calvarial margins toward the center of bone defect in 12 weeks. We observed similar increasing rate of bone ingrowth and percentage of bone formation within coated and uncoated implants, all of which achieved a successful bridging of the defect in 12 weeks after the implantation. CONCLUSIONS: This study demonstrated that the EBM porous Ti6Al4V implant not only reduced the stress-shielding but also exerted appropriate osteoconductive properties, as well as the apatite coated group. The results opened up the possibility of using purely porous titanium alloy scaffolds to reconstruct specific bone defects in the maxillofacial and orthopedic fields.

  9. Evaluation of metal ion release from Ti6Al4V and Co-Cr-Mo casting alloys: in vivo and in vitro study.

    Science.gov (United States)

    El Sawy, Amal A; Shaarawy, Mohammed A

    2014-02-01

    The aim of this study was to evaluate the amount of ions released from Ti6Al4V and Co-Cr-Mo alloys both in vivo and in vitro. Twenty-one discs of each alloy were constructed and divided into seven groups. Three specimens from each group were immersed in a buffered saline solution over a period of 1, 3, 5, 7, 14, 21, and 28 days. Twenty-eight participants were also included in the study, where the study group consisted of 14 mandibular partially edentulous patients, and the control group consisted of 14 volunteers. The study group was further divided into two equal groups: the first group received removable partial dentures (RPDs) constructed from Co-Cr-Mo alloy, while the second group received RPDs constructed from Ti6Al4V alloy. Saliva samples were collected from each participant over the same study period. The conditioning media and saliva samples were analyzed using a spectrophotometer. One-way ANOVA and Tukey tests were used for statistical analysis (p metal ions released from the studied alloys were significantly higher in the in vitro than in the in vivo study group during the follow-up periods. A statistically significant increase in ion concentrations of the different elements for both alloys was found with time (p metallic ions from Co-Cr-Mo and Ti6Al4V alloys were higher in the buffered saline solutions than in the studied saliva samples and control groups; however, these amounts were still within the physiological limit of trace elements in the human body. © 2013 by the American College of Prosthodontists.

  10. Fatigue performance of laser additive manufactured Ti-6Al-4V in very high cycle fatigue (VHCF) regime up to 109 cycles

    Science.gov (United States)

    Wycisk, Eric; Siddique, Shafaqat; Herzog, Dirk; Walther, Frank; Emmelmann, Claus

    2015-12-01

    Additive manufacturing technologies are in the process of establishing themselves as an alternative production technology to conventional manufacturing such as casting or milling. Especially laser additive manufacturing (LAM) enables the production of metallic parts with mechanical properties comparable to conventionally manufactured components. Due to the high geometrical freedom in LAM the technology enables the production of ultra-light weight designs and therefore gains increasing importance in aircraft and space industry. The high quality standards of these industries demand predictability of material properties for static and dynamic load cases. However, fatigue properties especially in the very high cycle fatigue regime until 109 cycles have not been sufficiently determined yet. Therefore this paper presents an analysis of fatigue properties of laser additive manufactured Ti-6Al-4V under cyclic tension-tension until 107 cycles and tension-compression load until 109 cycles. For the analysis of laser additive manufactured titanium alloy Ti-6Al-4V Woehler fatigue tests under tension-tension and tension-compression were carried out in the high cycle and very high cycle fatigue regime. Specimens in stress-relieved as well as hot-isostatic-pressed conditions were analyzed regarding crack initiation site, mean stress sensitivity and overall fatigue performance. The determined fatigue properties show values in the range of conventionally manufactured Ti-6Al-4V with particularly good performance for hot-isostatic-pressed additive-manufactured material. For all conditions the results show no conventional fatigue limit but a constant increase in fatigue life with decreasing loads. No effects of test frequency on life span could be determined. However, independently of testing principle, a shift of crack initiation from surface to internal initiation could be observed with increasing cycles to failure.

  11. In situ synthesized TiB-TiN reinforced Ti6Al4V alloy composite coatings: microstructure, tribological and in-vitro biocompatibility.

    Science.gov (United States)

    Das, Mitun; Bhattacharya, Kaushik; Dittrick, Stanley A; Mandal, Chitra; Balla, Vamsi Krishna; Sampath Kumar, T S; Bandyopadhyay, Amit; Manna, Indranil

    2014-01-01

    Wear resistant TiB-TiN reinforced Ti6Al4V alloy composite coatings were deposited on Ti substrate using laser based additive manufacturing technology. Ti6Al4V alloy powder premixed with 5wt% and 15wt% of boron nitride (BN) powder was used to synthesize TiB-TiN reinforcements in situ during laser deposition. Influences of laser power, scanning speed and concentration of BN on the microstructure, mechanical, in vitro tribological and biological properties of the coatings were investigated. Microstructural analysis of the composite coatings showed that the high temperature generated due to laser interaction with Ti6Al4V alloy and BN results in situ formation of TiB and TiN phases. With increasing BN concentration, from 5wt% to 15wt%, the Young's modulus of the composite coatings, measured by nanoindentation, increased from 170±5GPa to 204±14GPa. In vitro tribological tests showed significant increase in the wear resistance with increasing BN concentration. Under identical test conditions TiB-TiN composite coatings with 15wt% BN exhibited an order of magnitude less wear rate than CoCrMo alloy-a common material for articulating surfaces of orthopedic implants. Average top surface hardness of the composite coatings increased from 543±21HV to 877±75HV with increase in the BN concentration. In vitro biocompatibility and flow cytometry study showed that these composite coatings were non-toxic, exhibit similar cell-materials interactions and biocompatibility as that of commercially pure titanium (CP-Ti) samples. In summary, excellent in vitro wear resistance, high stiffness and suitable biocompatibility make these composite coatings as a potential material for load-bearing articulating surfaces towards orthopaedic implants. © 2013 Elsevier Ltd. All rights reserved.

  12. On the development of a dual-layered diamond-coated tool for the effective machining of titanium Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Srinivasan, Balaji; Rao, Balkrishna C; Ramachandra Rao, M S

    2017-01-01

    This work is focused on the development of a dual-layered diamond-coated tungsten carbide tool for machining titanium Ti-6Al-4V alloy. A hot-filament chemical vapor deposition technique was used to synthesize diamond films on tungsten carbide tools. A boron-doped diamond interlayer was added to a microcrystalline diamond layer in an attempt to improve the interface adhesion strength. The dual-layered diamond-coated tool was employed in machining at cutting speeds in the range of 70 to 150 m min −1 with a lower feed and a lower depth of cut of 0.5 mm rev −1 and 0.5 mm, respectively, to operate in the transition from adhesion- to diffusion-tool-wear and thereby arrive at suitable conditions for enhancing tool life. The proposed tool was then compared, on the basis of performance under real-time cutting conditions, with commercially available microcrystalline diamond, nanocrystalline diamond, titanium nitride and uncoated tungsten carbide tools. The life and surface finish of the proposed dual-layered tool and uncoated tungsten carbide were also investigated in interrupted cutting such as milling. The results of this study show a significant improvement in tool life and finish of Ti-6Al-4V parts machined with the dual-layered diamond-coated tool when compared with its uncoated counterpart. These results pave the way for the use of a low-cost tool, with respect to, polycrystalline diamond for enhancing both tool life and machining productivity in critical sectors fabricating parts out of titanium Ti-6Al-4V alloy. The application of this coating technology can also be extended to the machining of non-ferrous alloys owing to its better adhesion strength. (paper)

  13. Fatigue performance of laser additive manufactured Ti-6Al-4V in very high cycle fatigue (VHCF regime up to 109 cycles

    Directory of Open Access Journals (Sweden)

    Eric eWycisk

    2015-12-01

    Full Text Available Additive manufacturing technologies are in the process of establishing themselves as an alternative production technology to conventional manufacturing such as casting or milling. Especially laser additive manufacturing (LAM enables the production of metallic parts with mechanical properties comparable to conventionally manufactured components. Due to the high geometrical freedom in LAM the technology enables the production of ultra-light weight designs and therefore gains increasing importance in aircraft and space industry. The high quality standards of these industries demand predictability of material properties for static and dynamic load cases. However, fatigue properties especially in the very high cycle fatigue regime until 109 cycles have not been sufficiently determined yet. Therefore this paper presents an analysis of fatigue properties of laser additive manufactured Ti-6Al-4V under cyclic tension-tension until 107 cycles and tension-compression load until 109 cycles.For the analysis of laser additive manufactured titanium alloy Ti-6Al-4V Woehler fatigue tests under tension-tension and tension-compression were carried out in the high cycle and very high cycle fatigue regime. Specimens in stress-relieved as well as hot-isostatic-pressed conditions were analyzed regarding crack initiation site, mean stress sensitivity and overall fatigue performance. The determined fatigue properties show values in the range of conventionally manufactured Ti-6Al-4V with particularly good performance for hot-isostatic-pressed additive-manufactured material. For all conditions the results show no conventional fatigue limit but a constant increase in fatigue life with decreasing loads. No effects of test frequency on life span could be determined. However, independently of testing principle, a shift of crack initiation from surface to internal initiation could be observed with increasing cycles to failure.

  14. Investigation of nano-structured Zirconium oxide film on Ti6Al4V substrate to improve tribological properties prepared by PIII&D

    Energy Technology Data Exchange (ETDEWEB)

    Saleem, Sehrish [Department of Physics, Government College University, Lahore 54000 (Pakistan); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Ahmad, R., E-mail: ahriaz@gcu.edu.pk [Department of Physics, Government College University, Lahore 54000 (Pakistan); Centre for Advanced Studies in Physics (CASP), Government College University, Lahore 54000 (Pakistan); Ayub, R. [Centre for Advanced Studies in Physics (CASP), Government College University, Lahore 54000 (Pakistan); Ikhlaq, Uzma [Department of Physics, Government College University, Lahore 54000 (Pakistan); Jin, Weihong; Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)

    2017-02-01

    Highlights: • ZrO{sub 2} film was deposited on Ti6Al4V alloy using the plasma immersion ion implantation and deposition at various bias voltage. • The deposited film was characterized by XPS, AFM, Ellipometry, Nano-indentation and Pin-on disk machine. • A dense zirconium oxide film with the maximum thickness 108 nm was formed at maximum applied voltage. • The hardness and wear resistance of film is much higher as compared to the substrate. - Abstract: Plasma immersion ion implantation and deposition (PIII&D) is the most attractive and efficient technique used in the medical field to tailor materials for biomedical applications. In the present study zirconium oxide nano-structured thin films were deposited on surface of Ti6Al4V alloy for bias voltages of 15, 20 and 25 kV. The chemical composition, surface roughness and thickness of deposited films were characterized by the x-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) and ellipsometry respectively. The XPS results confirm the formation of a dense zirconium oxide film of the treated specimens. AFM results exhibit a smooth film with maximum roughness of about 8.4 nm is formed. The thickness of the film is increased with the increase in bias voltages and is maximum at 25 kV. The effect of bias voltages on wear characteristics was further investigated by pin-on-disk test. It is observed that the friction coefficient is reduced, whereas wear resistance is enhanced and it is found to be maximum at 25 kV compared to the other bias voltages. Nanohardness is improved up to twice compared to untreated specimen at the maximum bias voltage. Therefore, it is concluded that deposition of zirconium oxide using the PIII&D is produced a dense layer on the substrate surface, which can be used as a promising candidate for the improved tribological properties of Ti6Al4V.

  15. Friction and wear study of diamond-like carbon gradient coatings on Ti6Al4V substrate prepared by plasma source ion implant-ion beam enhanced deposition

    International Nuclear Information System (INIS)

    Jiang, Shuwen; Jiang Bin; Li Yan; Li Yanrong; Yin Guangfu; Zheng Changqiong

    2004-01-01

    DLC gradient coatings had been deposited on Ti6Al4V alloy substrate by plasma source ion implantation-ion beam enhanced deposition method and their friction and wear behavior sliding against ultra high molecular weight polyethylene counterpart were investigated. The results showed that DLC gradient coated Ti6Al4V had low friction coefficient, which reduced 24, 14 and 10% compared with non-coated Ti6Al4V alloy under dry sliding, lubrication of bovine serum and 0.9% NaCl solution, respectively. DLC gradient coated Ti6Al4V showed significantly improved wear resistance, the wear rate was about half of non-coated Ti6Al4V alloy. The wear of ultra high molecular weight polyethylene counterpart was also reduced. High adhesion to Ti6Al4V substrate of DLC gradient coatings and surface structure played important roles in improved tribological performance, serious oxidative wear was eliminated when DLC gradient coating was applied to the Ti6Al4V alloy

  16. Evoluzione della relazione cristallografica tra la fase ? e la fase ? in una lega Ti-6Al-4V compressa a 800°C

    OpenAIRE

    Cabibbo, M.; Fabrizi, A.; di Salvia, A.; Quercetti, G.

    2013-01-01

    La relazione reciproca tra le due fasi costituenti la lega Ti-6Al-4V, ?HCP e ?BBC, è tale da avere:, che inletteratura è nota come relazione d’orientamento di Burgers. La coerenza delle due fasi è controllata da questareciproca relazione cristallografica. La perdita di coerenza tra le fasi durante la deformazione può provenire daun non parallelismo tra i due piani cristallografici di confine. Il presente lavoro illustra una caratterizzazioneTEM dell’evoluzione lamellare di coerenza all’interf...

  17. Mécanismes d'usure des outils coupants en usinage à sec de l'alliage de titane aéronautique Ti-6Al-4V

    OpenAIRE

    NOUARI , Mohammed; CALAMAZ , Madalina; GIROT , Franck

    2008-01-01

    International audience; In the present study, the titanium alloy 'Ti-6Al-4V' is orthogonally machined without cutting fluid. During experiments, the cemented carbide tools were rigidly mounted on the tool holder with rake angles of 0°, 15° and 30°. Three cutting speeds of 15, 30 and 60 m/min and three feeds of 0.1, 0.2, and 0.3 mm were selected. The experimental results show that the tool catastrophic failure occurs just after the first pass of cutting for all cutting parameters when using th...

  18. Efecto de los parámetros de GTAW pulsado en la microestructura y propiedades de la aleación de titanio Ti-6Al-4V

    OpenAIRE

    Aristizábal Mesa, Santiago

    2013-01-01

    Resumen: Se estudió el efecto de la frecuencia de la corriente alterna y la frecuencia de pulso en la microestructura, tamaño de grano, resistencia a la tracción, ductilidad y dureza de láminas de la aleación de titanio Ti-6Al-4V empleando proceso de soldadura GTAW con corriente alterna pulsada. Para ello, se tomaron cuatro frecuencias de pulso (0, 2, 6 y 10 Hz) y tres frecuencias de la corriente alterna (40, 180 y 400 Hz), con el fin de determinar las combinaciones de estas variables que gen...

  19. Peculiarities of single track formation from TI6AL4V alloy at different laser power densities by selective laser melting

    Directory of Open Access Journals (Sweden)

    Yadroitsava, I.

    2015-11-01

    Full Text Available This paper describes the geometrical characteristics of single tracks manufactured by selective laser melting (SLM at different laser powers (20-170 W and scanning speeds (0.1-2.0 m/s. Simulation of temperature distribution during processing is carried out. A conclusion about the optimal process parameters and peculiarities of selective laser melting of Ti6Al4V alloy at low and high laser powers and scanning speeds is reached. The analysis of temperature fields creates opportunities to build parts with the desired properties by using SLM.

  20. Fatigue Performance of Ti-6Al-4V Additively Manufactured Specimens with Integrated Capillaries of an Embedded Structural Health Monitoring System.

    Science.gov (United States)

    Hinderdael, Michaël; Strantza, Maria; De Baere, Dieter; Devesse, Wim; De Graeve, Iris; Terryn, Herman; Guillaume, Patrick

    2017-08-25

    Additive manufacturing (AM) of metals offers new possibilities for the production of complex structures. Up to now, investigations on the mechanical response of AM metallic parts show a significant spread and unexpected failures cannot be excluded. In this work, we focus on the detection of fatigue cracks through the integration of a Structural Health Monitoring (SHM) system in Ti-6Al-4V specimens. The working principle of the presented system is based on the integration of small capillaries that are capable of detecting fatigue cracks. Four-point bending fatigue tests have been performed on Ti-6Al-4V specimens with integrated capillaries and compared to the reference specimenswithout capillaries. Specimens were produced by conventional subtractive manufacturing of wrought material and AM, using the laser based Directed Energy Deposition (DED) process. In this study, we investigated the effect of the presence of the capillary on the fatigue strength and fatigue initiation location. Finite element (FEM) simulations were performed to validate the experimental test results. The presence of a drilled capillary in the specimens did not alter the fatigue initiation location. However, the laser based DED production process introduced roughness on the capillary surface that altered the fatigue initiation location to the capillary surface. The fatigue performance was greatly reduced when considering a printed capillary. It is concluded that the surface quality of the integrated capillary is of primary importance in order not to influence the structural integrity of the component to be monitored.

  1. Quantifying the mode II critical strain energy release rate of borate bioactive glass coatings on Ti6Al4V substrates.

    Science.gov (United States)

    Matinmanesh, A; Li, Y; Clarkin, O; Zalzal, P; Schemitsch, E H; Towler, M R; Papini, M

    2017-11-01

    Bioactive glasses have been used as coatings for biomedical implants because they can be formulated to promote osseointegration, antibacterial behavior, bone formation, and tissue healing through the incorporation and subsequent release of certain ions. However, shear loading on coated implants has been reported to cause the delamination and loosening of such coatings. This work uses a recently developed fracture mechanics testing methodology to quantify the critical strain energy release rate under nearly pure mode II conditions, G IIC , of a series of borate-based glass coating/Ti6Al4V alloy substrate systems. Incorporating increasing amounts of SrCO 3 in the glass composition was found to increase the G IIC almost twofold, from 25.3 to 46.9J/m 2 . The magnitude and distribution of residual stresses in the coating were quantified, and it was found that the residual stresses in all cases distributed uniformly over the cross section of the coating. The crack was driven towards, but not into, the glass/Ti6Al4V substrate interface due to the shear loading. This implied that the interface had a higher fracture toughness than the coating itself. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Ion release and surface oxide composition of AISI 316L, Co-28Cr-6Mo, and Ti-6Al-4V alloys immersed in human serum albumin solutions.

    Science.gov (United States)

    Karimi, Shima; Alfantazi, Akram M

    2014-07-01

    The long-term weight loss, ion release, and surface composition of 316L, Co-28Cr-6Mo and Ti-6Al-4V alloys were investigated in a simulated body environment. The samples were immersed in phosphate-buffered saline (PBS) solutions with various human serum albumin (HSA) concentrations for 8, 14, and 22 weeks. The specimens initially lost weight up to 14 weeks and then slightly gained weight. The analysis of the released ions was performed by induced coupled plasma-optical emission spectrometer (ICP-OES). The results revealed that the precipitation of the dissolved Fe and Co could cause the weight gain of the 316L and Co-28Cr-6Mo alloys. The surface chemistry of the specimens was determined by X-ray photoelectron spectroscopy (XPS). The XPS analysis of Co-28Cr-6Mo alloy showed that the interaction of Mo with HSA is different from Mo with bovine serum albumin (BSA). This was also observed for Na adsorption into the oxide layer of Ti-6Al-4V alloy in the presence of HSA and BSA. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

  3. Reactive wetting of Ti-6Al-4V alloy by molten Al 4043 and 6061 alloys at 600-700 C

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Qiaoli; Li, Fuxiang; Jin, Peng; Yu, Weiyuan [Lanzhou Univ. of Technology (China). State Key Lab. of Advanced Processing and Recycling of Non-ferrous Metal

    2017-06-15

    Wetting of Ti-6Al-4V alloy by two industrial grade Al alloys (i.e., Al 6061 and 4043 alloys) was studied using the sessile drop method at 600-700 C under high vacuum. Al/Ti-6Al-4V is a typical reactive wetting system with good final wettability accompanied by the formation of precursor film which is actually an extended reaction layer. The formation mechanism for the precursor film is ''subcutaneous infiltration''. The small amount of alloying element Si in the alloys can cause significant segregation at the liquid/solid interface which satisfies the thermodynamic condition. The wetting behavior can be described by the classic reaction product control models, and Ti{sub 7}Al{sub 5}Si{sub 12} decomposition and Al{sub 3}Ti formation correspond to the two spreading stages. The small difference in alloying elements in Al 6061 and 4043 resulted in distinctly different interface structures, formation of precursor film and spreading dynamics, especially for the Si segregation at the interface.

  4. Attachment and proliferation of neonatal rat calvarial osteoblasts on Ti6Al4V: effect of surface chemistries of the alloy.

    Science.gov (United States)

    Lee, T M; Chang, E; Yang, C Y

    2004-01-01

    This study examined the cell attachment and proliferation of neonatal rat calvarial osteoblasts on Ti6Al4V alloy as affected by the surface modifications. The modifications could alter simultaneously the surface chemistries of the alloy (elemental difference of Ti, Al, V, Cu and Ni about 300-600mum thick examined by EDS) as well as the XPS nano-surface characteristics of oxides on the metal surface (chemistries of oxides, amphoteric OH group adsorbed on oxides, and oxide thickness). Three materials including two from modifications and a control were examined. It is argued that a slight change of the nano-surface characteristics of oxides as a result of the modifications neither alters the in vitro capability of Ca and P ion adsorption nor affects the metal ion dissolution behavior of the alloy. This implies that any influence on the cytocompatibility of the materials should only be correlated to the effect of surface chemistries of the alloy and the associated metal ion dissolution behavior of the alloy. The experimental results suggest that the cell response of neonatal rat calvarial osteoblasts on the Ti6Al4V alloy should neither be affected by the variation of surface chemistries of the alloy in a range studied.

  5. Hydrogen absorption and desorption in a duplex-annealed Ti-6Al-4V alloy during exposure to different hydrogen-containing environments

    International Nuclear Information System (INIS)

    Eliezer, D.; Tal-Gutelmacher, E.; Cross, C.E.; Boellinghaus, Th.

    2006-01-01

    Based on its excellent combination of a high strength/weight ratio and good corrosion behavior, Ti-6Al-4V alloy is ranked among the most important advanced materials for a variety of industrial applications. However, in many of these technological applications, this alloy is exposed to environments which can act as sources of hydrogen, and severe problems may arise based on its susceptibility to hydrogen embrittlement. Even small hydrogen concentrations might lead to failure. Consequently, a comprehensive knowledge of hydrogen's absorption/desorption behavior and interactions between hydrogen and different microstructural features is necessary to better understand the desorption and trapping mechanisms, the types of the trap sites, and the trapped hydrogen content, in order to determine the safe service conditions of this alloy in the industry. In this paper, different characteristics of hydrogen's absorption/desorption behavior and trapping in a duplex-annealed Ti-6Al-4V alloy are studied by means of thermal desorption spectroscopy (TDS). Spectra analysis is supported by data from a variety of other experimental techniques, such as LECO hydrogen determinator, XRD and microstructure investigations by means of optical and electron microscopy. Hydrogen evolution is found to be a very complex process, being affected by the way hydrogen was initially introduced to the alloy, the phase transformations that may occur during the thermal analysis and the presence of potential trapping sites

  6. Layered Composite of TiC-TiB2 to Ti-6Al-4V in Graded Composition by Combustion Synthesis in High-gravity Field

    International Nuclear Information System (INIS)

    Huang Xuegang; Zhao Zhongmin; Zhang Long

    2013-01-01

    By taking combustion synthesis to prepare solidified TiB 2 matrix ceramic in high-gravity field, the layered composite of TiC-TiB 2 ceramic to Ti-6Al-4V substrate in graded composition was achieved. XRD, FESEM and EDS results showed that the bulk full-density solidified TiC-TiB 2 composite was composed of fine TiB 2 platelets, TiC irregular grains, a few of α-Al 2 O 3 inclusions and Cr alloy phases, and α'-Ti phases alternating with Ti-enriched carbides constituted the matrix of the joint in which fine TiB platelets were embedded, whereas some C, B atoms were also detected at the heat-affected zone of Ti-6A1-4V substrate. The layered composite of the solidified ceramic to Ti-6Al-4V substrate in graded composition with continuous microstructure was considered a result of fused joint and inter-diffusion between liquid ceramic and surface-molten Ti alloy, followed by TiB 2 -Ti peritectic reaction and subsequent eutectic reaction in TiC-TiB-Ti ternary system.

  7. An Investigation on the Wear Resistance and Fatigue Behaviour of Ti-6Al-4V Notched Members Coated with Hydroxyapatite Coatings

    Directory of Open Access Journals (Sweden)

    Reza H Oskouei

    2016-02-01

    Full Text Available In this study, surface properties of Ti-6Al-4V alloy coated with hydroxyapatite coatings were investigated. Wear resistance and fatigue behaviour of samples with coating thicknesses of 10 and 50 µm as well as uncoated samples were examined. Wear experiments demonstrated that the friction factor of the uncoated titanium decreased from 0.31 to 0.06, through a fluctuating trend, after 50 cycles of wear tests. However, the friction factor of both the coated samples (10 and 50 µm gradually decreased from 0.20 to 0.12 after 50 cycles. At the end of the 50th cycle, the penetration depth of the 10 and 50 µm coated samples were 7.69 and 6.06 µm, respectively. Fatigue tests showed that hydroxyapatite coatings could improve fatigue life of a notched Ti-6Al-4V member in both low and high cycle fatigue zones. It was understood, from fractography of the fracture surfaces, that the fatigue zone of the uncoated specimens was generally smaller in comparison with that of the coated specimens. No significant difference was observed between the fatigue life of coated specimens with 10 and 50 µm thicknesses.

  8. Cycle oxidation behavior and anti-oxidation mechanism of hot-dipped aluminum coating on TiBw/Ti6Al4V composites with network microstructure.

    Science.gov (United States)

    Li, X T; Huang, L J; Wei, S L; An, Q; Cui, X P; Geng, L

    2018-04-10

    Controlled and compacted TiAl 3 coating was successfully fabricated on the network structured TiBw/Ti6Al4V composites by hot-dipping aluminum and subsequent interdiffusion treatment. The network structure of the composites was inherited to the TiAl 3 coating, which effectively reduces the thermal stress and avoids the cracks appeared in the coating. Moreover, TiB reinforcements could pin the TiAl 3 coating which can effectively improve the bonding strength between the coating and composite substrate. The cycle oxidation behavior of the network structured coating on 873 K, 973 K and 1073 K for 100 h were investigated. The results showed the coating can remarkably improve the high temperature oxidation resistance of the TiBw/Ti6Al4V composites. The network structure was also inherited to the Al 2 O 3 oxide scale, which effectively decreases the tendency of cracking even spalling about the oxide scale. Certainly, no crack was observed in the coating after long-term oxidation due to the division effect of network structured coating and pinning effect of TiB reinforcements. Interfacial reaction between the coating and the composite substrate occurred and a bilayer structure of TiAl/TiAl 2 formed next to the substrate after oxidation at 973 K and 1073 K. The anti-oxidation mechanism of the network structured coating was also discussed.

  9. Ductility improvement due to martensite α' decomposition in porous Ti-6Al-4V parts produced by selective laser melting for orthopedic implants.

    Science.gov (United States)

    Sallica-Leva, E; Caram, R; Jardini, A L; Fogagnolo, J B

    2016-02-01

    Ti-6Al-4V parts obtained by selective laser melting typically have an acicular α' martensitic microstructure whose ductility is low. Thus, post-heat treatments are useful for increasing ductility. In this work, the effects of sub-β-transus heat treatments on the mechanical properties of Ti-6Al-4V parts with porous structures are correlated with martensite α' phase decomposition. The precipitation of β phase and the gradual transformation of α' into α phase by the diffusion of excess vanadium from α' to β phase are proposed to be the main events of martensite α' phase decomposition in parts fabricated by selective laser melting. The heat treatment performed at 650°C for 1h produced no microstructural changes, but the samples treated for at the same temperature 2h showed a fine precipitation of β phase along the α' needle boundaries. The heat treatment performed at 800°C for 1 or 2h produced a fine α+β microstructure, in which β phase are present as particles fewer in number and larger in size, when compared with the ones present in the sample heat-treated at 650°C for 2h. Heat-treatment of the parts at 800°C for 2h proved to be the best condition, which improved the ductility of the samples while only slightly reducing their strength. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Comparison of Single Ti6Al4V Struts Made Using Selective Laser Melting and Electron Beam Melting Subject to Part Orientation

    Directory of Open Access Journals (Sweden)

    Volker Weißmann

    2017-03-01

    Full Text Available The use of additive manufacturing technologies to produce lightweight or functional structures is widespread. Especially Ti6Al4V plays an important role in this development field and parts are manufactured and analyzed with the aim to characterize the mechanical properties of open-porous structures and to generate scaffolds with properties specific to their intended application. An SLM and an EBM process were used respectively to fabricate the Ti6Al4V single struts. For mechanical characterization, uniaxial compression tests and hardness measurements were conducted. Furthermore, the struts were manufactured in different orientations for the determination of the mechanical properties. Roughness measurements and a microscopic characterization of the struts were also carried out. Some parts were characterized following heat treatment (hot isostatic pressing. A functional correlation was found between the compressive strength and the slenderness ratio (λ as well as the equivalent diameter (d and the height (L of EBM and SLM parts. Hardness investigations revealed considerable differences related to the microstructure. An influence of heat treatment as well as of orientation could be determined. In this work, we demonstrate the influence of the fabrication quality of single struts, the roughness and the microstructure on mechanical properties as a function of orientation.

  11. Technics Research on Polycrystalline Cubic Boron Nitride Cutting Tools Dry Turning Ti-6AL-4V Alloy Based on Orthogonal Experimental Design

    Directory of Open Access Journals (Sweden)

    Jia Yunhai

    2018-01-01

    Full Text Available Ti-6Al-4V components are the most widely used titanium alloy products not only in the aerospace industry, but also for bio-medical applications. The machine-ability of titanium alloys is impaired by their high temperature chemical reactivity, low thermal conductivity and low modulus of elasticity. Polycrystalline cubic boron nitride represents a substitute tool material for turning titanium alloys due to its high hardness, wear resistance, thermal stability and hot red hardness. For determination of suitable cutting parameters in dry turning Ti-6AL-4V alloy by Polycrystalline cubic boron nitride cutting tools, the samples, 300mm in length and 100mm in diameter, were dry machined in a lathe. The turning suitable parameters, such as cutting speed, feed rate and cut depth were determined according to workpieces surface roughness and tools flank wear based on orthogonal experimental design. The experiment showed that the cutting speed in the range of 160~180 m/min, the feed rate is 0.15 mm/rev and the depth of cut is 0.20mm, ideal workpiece surface roughness and little cutting tools flank wear can be obtained.

  12. Wear studies on ZrO2-filled PEEK as coating bearing materials for artificial cervical discs of Ti6Al4V

    International Nuclear Information System (INIS)

    Song, Jian; Liu, Yuhong; Liao, Zhenhua; Wang, Song; Tyagi, Rajnesh; Liu, Weiqiang

    2016-01-01

    Polyetheretherketone (PEEK) and its composite coatings are believed to be the potential candidates' bio-implant materials. However, these coatings have not yet been used on the surface of titanium-based orthopedics and joint products and very few investigations on the tribological characteristics could be found in the published literature till date. In this study, the wettabilities, composition and micro-hardness were characterized using contact angle measurement, scanning electron microscopy (SEM) and hardness tester. The tribological tests were conducted using a ball-on-disc contact pair under 25% newborn calf serum (NCS) lubricated condition. For comparison, bare Ti6Al4V was studied. The obtained results revealed that those PEEK/ZrO 2 composite coatings could improve the tribological properties of Ti6Al4V significantly. Adhesive wear and mild abrasive wear might be the dominant wear and failure mechanisms for PEEK/ZrO 2 composite coatings in NCS lubricated condition. After comprehensive evaluation in the present study, 5 wt.% ZrO 2 nanoparticles filled PEEK coating displayed the optimum tribological characteristics and could be taken as a potential candidate for the bearing material of artificial cervical disc. - Graphical abstract: Polyetheretherketone (PEEK) is a type of biomaterial which might be used in surface modification. In this study, the wettabilities, composition, hardness, friction and wear characteristics of PEEK/ZrO 2 coatings were investigated, compared with bare Ti6Al4V sample. After comprehensive evaluation, 5 wt.% ZrO 2 nanoparticles filled PEEK coating displayed the optimum tribological characteristics and could be taken as a potential candidate for the bearing material of artificial cervical disc. - Highlights: • PEEK coating were filled by ZrO 2 nanoparticles with different weight percentage. • The lubrication regime of all the tested samples are boundary lubrication. • Adhesive wear and mild abrasive wear were the dominant wear

  13. Laser and plasma dental soldering techniques applied to Ti-6Al-4V alloy: ultimate tensile strength and finite element analysis.

    Science.gov (United States)

    Castro, Morgana G; Araújo, Cleudmar A; Menegaz, Gabriela L; Silva, João Paulo L; Nóbilo, Mauro Antônio A; Simamoto Júnior, Paulo Cézar

    2015-05-01

    The literature provides limited information regarding the performance of Ti-6Al-4V laser and plasma joints welded in prefabricated bars in dental applications. The purpose of this study was to evaluate the mechanical strength of different diameters of Ti-6Al-4V alloy welded with laser and plasma techniques. Forty-five dumbbell-shaped rods were created from Ti-6Al-4V and divided into 9 groups (n=5): a control group with 3-mm and intact bars; groups PL2.5, PL3, PL4, and PL5 (specimens with 2.5-, 3-, 4-, and 5-mm diameters welded with plasma); and groups L2.5, L3, L4, and L5 (specimens with 2.5-, 3-, 4-, and 5-mm diameters welded with laser). The specimens were tested for ultimate tensile strength (UTS), and elongation percentages (EP) were obtained. Fractured specimens were analyzed by stereomicroscopy, and welded area percentages (WAP) were calculated. Images were made with scanning electron microscopy. In the initial analysis, the data were analyzed with a 2-way ANOVA (2×4) and the Tukey Honestly Significant Difference (HSD) test. In the second analysis, the UTS and EP data were analyzed with 1-way ANOVA, and the Dunnett test was used to compare the 4 experimental groups with the control group (α=.05). The Pearson and Spearman correlation coefficient tests were applied to correlate the study factors. Finite element models were developed in a workbench environment with boundary conditions simulating those of a tensile test. The 2-way ANOVA showed that the factors welding type and diameter were significant for the UTS and WAP values. However, the interaction between them was not significant. The 1-way ANOVA showed statistically significant differences among the groups for UTS, WAP, and EP values. The Dunnett test showed that all the tested groups had lower UTS and EP values than the control group. The 2.5- and 3-mm diameter groups showed higher values for UTS and WAP than the other test groups. A positive correlation was found between welded area percentage and UTS

  14. Characterization of Friction Welded Titanium Alloy and Stainless Steel with a Novel Interlayer Geometry

    Science.gov (United States)

    Kumar, R.; Balasubramanian, M.

    The main purpose of the current research work is to identify and investigate a novel method of holding an intermediate metal and to evaluate its metallurgical and mechanical properties. Copper was used as an interlayer material for the welding of this dissimilar Ti-6Al-4V (Ti alloy) and 304L stainless steel (SS). The study shows that the input parameters and surface geometry played a very significant role in producing a good quality joints with minimum heat affected zone and metal loss. A sound weld was achieved between Ti-6Al-4V and SS304L, on the basis of the earlier experiments conducted by the authors in their laboratory, by using copper rod as intermediate metal. Box-Behnken method was used for performing a minimum number of experiments for the study. In the present study, Ti-6Al-4V alloy and SS304L were joined by a novel method of holding the interlayer and new surface geometry for the interlayer. Initially, the drop test was used for determining the quality of the fabricated joint and, subsequently, non-destructive techniques like radiography and C-scan were used. Further optical micrograph, SEM-EDS, hardness and tensile test were done for understanding the performance of the joint.

  15. Correlations between the post-HIP treatment, resulting microstructure and fatigue behaviour of prealloyed Ti6Al4V powder compacts

    International Nuclear Information System (INIS)

    Wirth, G.; Grundhoff, K.J.; Smarsly, W.

    1985-01-01

    Prealloyed Ti6Al4V powders, hot isostatically pressed in the (alpha + beta) temperature range, always possess a mixed microstructure of lenticular and equiaxed parts. Numerous treatments have been used to improve microstructural homogeneity, especially to achieve fine equiaxed grains well known to possess good HCF properties. In this contribution, four different conditions of HIP compacts from ultraclean PREP powder were investigated together with PSV powder compacted by combined die forging (CDF). The HIP compacts had pure equiaxed and lenticular, a mixture of both (as HIP) as well as a swaged + beta annealed microstructure. The best HCF fatigue strength was correlated to the last condition instead of the expected equiaxed microstructure. CDF resulted in a homogeneous equiaxed microstructure which thus could be achieved by a one-step compaction process directly from untreated powder. 12 references

  16. Optimization of technological parameters in the calescent superplastic bulge forming of Ti-6Al-4V alloys sheet based on fuzzy neural network

    Energy Technology Data Exchange (ETDEWEB)

    Chen, M.H.; Gao, L.; Zuo, D.W.; Wang, M. [Coll. of Mechanical and Electrical Engineering, Nanjing Univ. of Aeronautics and Astronautics, Nanjing (China); Zhu, Z.S. [Beijing Inst. of Aeronautics Materials, Beijing, BJ (China)

    2004-07-01

    The calescent superplastic bulge forming (CSPBF) of Ti-6Al-4V (TC4) alloy sheet was investigated using experimental method, and carried out the research that optimized its technological parameters using fuzzy neural network (FNN). The experimental results show that the CSPBF may save processing time, can also improve materials' formability as well as get ideal microstructure. The study indicated that the FNN adapt to solve complex nonlinear problem such as technological parameters of CSPBF of TC4 sheet. Utilizing optimized technological parameters successfully have formed the part of aerostat, the nonuniformity of wall thickness is less than 8% and part' forming time may be shorten 10minute. (orig.)

  17. Microstructure and wear property of the Ti5Si3/TiC reinforced Co-based coatings fabricated by laser cladding on Ti-6Al-4V

    Science.gov (United States)

    Weng, Fei; Yu, Huijun; Liu, Jianli; Chen, Chuanzhong; Dai, Jingjie; Zhao, Zhihuan

    2017-07-01

    Ti5Si3/TiC reinforced Co-based composite coatings were fabricated on Ti-6Al-4V titanium alloy by laser cladding with Co42 and SiC mixture. Microstructure and wear property of the cladding coatings with different content of SiC were investigated. During the cladding process, the original SiC dissolved and reacted with Ti forming Ti5Si3 and TiC. The complex in situ formed phases were found beneficial to the improvement of the coating property. Results indicated that the microhardness of the composite coatings was enhanced to over 3 times the substrate. The wear resistance of the coatings also showed distinct improvement (18.4-57.4 times). More SiC gave rise to better wear resistance within certain limits. However, too much SiC (20 wt%) was not good for the further improvement of the wear property.

  18. Comparative evaluation of laser-assisted micro-milling for AISI 316, AISI 422, TI-6AL-4V and Inconel 718 in a side-cutting configuration

    International Nuclear Information System (INIS)

    Shelton, Jonathan A; Shin, Yung C

    2010-01-01

    This paper is focused on numerical modeling and experimental evaluation of laser-assisted micro-milling (LAMM). An experimental setup consisting of a 25 W CO 2 laser, three-axis CNC linear stages and a high-speed spindle was used to implement the LAMM process. Micro-endmills between 100 and 300 µm in diameter were used to perform side-cutting operations with and without laser preheat on four materials: AISI 316, AISI 422, Ti-6Al-4V and Inconel 718. A three-dimensional transient finite-volume-based thermal model was used to analytically predict appropriate process parameters on the basis of material-removal temperatures. The effects of LAMM on the machined surface finish, edge burrs, tool wear and workpiece microstructure were evaluated experimentally.

  19. Dynamic Shear Deformation and Failure of Ti-6Al-4V and Ti-5Al-5Mo-5V-1Cr-1Fe Alloys.

    Science.gov (United States)

    Ran, Chun; Chen, Pengwan

    2018-01-05

    To study the dynamic shear deformation and failure properties of Ti-6Al-4V (Ti-64) alloy and Ti-5Al-5Mo-5V-1Cr-1Fe (Ti-55511) alloy, a series of forced shear tests on flat hat shaped (FHS) specimens for the two investigated materials was performed using a split Hopkinson pressure bar setup. The evolution of shear deformation was monitored by an ultra-high-speed camera (Kirana-05M). Localized shear band is induced in the two investigated materials under forced shear tests. Our results indicate that severe strain localization (adiabatic shear) is accompanied by a loss in the load carrying capacity, i.e., by a sudden drop in loading. Three distinct stages can be identified using a digital image correlation technique for accurate shear strain measurement. The microstructural analysis reveals that the dynamic failure mechanisms for Ti-64 and Ti-55511 alloys within the shear band are of a cohesive and adhesive nature, respectively.

  20. The development of Ti6Al4V based anti bacterial dental implant modified with TiO2 nanotube arrays doped silver metal (Ag)

    Science.gov (United States)

    Slamet, Bachtiar, B. M.; Wulan, P. P. D. K.; Setiadi, Sari, D. P.

    2017-05-01

    The development of Ti6Al4V based anti bacterial dental implant, modified with dopanted silver metal (Ag) TiO2 nanotube arrays (TiNTAs), is studied in this research. The condition inside the mouth is less foton energy, the dental implant material need to be modified with silver metal (Ag) dopanted TiNTAs. Modified TiNTAs used silver metal dopanted with Photo Assisted Deposition (PAD) method can be used as an electron trapper and produced hydroxyl radical, therefore it has antibacterial properties. The verification of antibacterial properties developed with biofilm static test using Streptococcus mutans bacteria model within 3 and 16 hours incubation, was characterized with XRD and SEM-EDX. Properties test result that resisting the biofilm growth effectively is TiNTAs/Ag/0,15, with 97,62 % disinfection bacteria sampel.

  1. Modelling of Mechanical Behavior at High Strain Rate of Ti-6al-4v Manufactured By Means of Direct Metal Laser Sintering Technique

    Science.gov (United States)

    Iannitti, Gianluca; Bonora, Nicola; Gentile, Domenico; Ruggiero, Andrew; Testa, Gabriel; Gubbioni, Simone

    2017-06-01

    In this work, the mechanical behavior of Ti-6Al-4V obtained by additive manufacturing technique was investigated, also considering the build direction. Dog-bone shaped specimens and Taylor cylinders were machined from rods manufactured by means of the EOSSINT M2 80 machine, based on Direct Metal Laser Sintering technique. Tensile tests were performed at strain rate ranging from 5E-4 s-1 to 1000 s-1 using an Instron electromechanical machine for quasistatic tests and a Direct-Tension Split Hopkinson Bar for dynamic tests. The mechanical strength of the material was described by a Johnson-Cook model modified to account for stress saturation occurring at high strain. Taylor cylinder tests and their corresponding numerical simulations were carried out in order to validate the constitutive model under a complex deformation path, high strain rates, and high temperatures.

  2. The effect of microstructure on fatigue performance of Ti-6Al-4V alloy after EDM surface treatment for application in orthopaedics.

    Science.gov (United States)

    Stráský, Josef; Janeček, Miloš; Harcuba, Petr; Bukovina, Michal; Wagner, Lothar

    2011-11-01

    Three different microstructures--equiaxed, bi-modal and coarse lamellar--are prepared from Ti-6Al-4V alloy. Electric discharge machining (EDM) with a high peak current (29 A) is performed in order to impose surface roughness and modify the chemical composition of the surface. Detailed scanning electron microscopy (SEM) investigation revealed a martensitic surface layer and subsurface heat affected zone (HAZ). EDX measurements showed carbon enriched remnants of the EDM process on the material surface. Rotating bending fatigue tests are undertaken for EDM processed samples for all three microstructures and also for electropolished-benchmark-samples. The fatigue performance is found to be rather poor and not particularly dependent on microstructure. The bi-modal microstructure shows a slightly superior high cycle fatigue performance. This performance can be further improved by a suitable heat treatment to an endurance limit of 200 MPa. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Faster methods for estimating arc centre position during VAR and results from Ti-6Al-4V and INCONEL 718 alloys

    Science.gov (United States)

    Nair, B. G.; Winter, N.; Daniel, B.; Ward, R. M.

    2016-07-01

    Direct measurement of the flow of electric current during VAR is extremely difficult due to the aggressive environment as the arc process itself controls the distribution of current. In previous studies the technique of “magnetic source tomography” was presented; this was shown to be effective but it used a computationally intensive iterative method to analyse the distribution of arc centre position. In this paper we present faster computational methods requiring less numerical optimisation to determine the centre position of a single distributed arc both numerically and experimentally. Numerical validation of the algorithms were done on models and experimental validation on measurements based on titanium and nickel alloys (Ti6Al4V and INCONEL 718). The results are used to comment on the effects of process parameters on arc behaviour during VAR.

  4. The Importance Of Surface Topography For The Biological Properties Of Nitrided Diffusion Layers Produced On Ti6Al4V Titanium Alloy

    Directory of Open Access Journals (Sweden)

    Wierzchoń T.

    2015-09-01

    Full Text Available Diffusion nitrided layers produced on titanium and its alloys are widely studied in terms of their application for cardiac and bone implants. The influence of the structure, the phase composition, topography and surface morphology on their biological properties is being investigated. The article presents the results of a study of the topography (nanotopography of the surface of TiN+Ti2N+αTi(N nitrided layers produced in low-temperature plasma on Ti6Al4V titanium alloy and their influence on the adhesion of blood platelets and their aggregates. The TEM microstructure of the produced layers have been examined and it was demonstrated that the interaction between platelets and the surface of the titanium implants subjected to glow-discharge nitriding can be shaped via modification of the roughness parameters of the external layer of the TiN titanium nitride nanocrystalline zone.

  5. Effect of Heat Treatment on Microstructure and Impact Toughness of Ti-6Al-4V Manufactured by Selective Laser Melting Process

    Directory of Open Access Journals (Sweden)

    Lee K.-A.

    2017-06-01

    Full Text Available This study manufactured Ti-6Al-4V alloy using one of the powder bed fusion 3D-printing processes, selective laser melting, and investigated the effect of heat treatment (650°C/3hrs on microstructure and impact toughness of the material. Initial microstructural observation identified prior-β grain along the building direction before and after heat treatment. In addition, the material formed a fully martensite structure before heat treatment, and after heat treatment, α and β phase were formed simultaneously. Charpy impact tests were conducted. The average impact energy measured as 6.0 J before heat treatment, and after heat treatment, the average impact energy increased by approximately 20% to 7.3 J. Fracture surface observation after the impact test showed that both alloys had brittle characteristics on macro levels, but showed ductile fracture characteristics and dimples at micro levels.

  6. Investigation of the microstructure and surface morphology of a Ti6Al4V plate fabricated by vacuum selective laser melting

    International Nuclear Information System (INIS)

    Sato, Yuji; Tsukamoto, Masahiro; Masuno, Shinichiro; Abe, Nobuyuki; Yamashita, Yorihiro; Yamashita, Kensuke; Tanigawa, Daichi

    2016-01-01

    As an additive manufacturing technology, the selective laser melting (SLM) process is useful to directly form complicated shapes. The SLM process in a vacuum has been used to fabricate three-dimensional Ti6Al4V (Ti64) plates because this method can control the phase transformation. To investigate the laser melting and solidification dynamics, the formation of a Ti64 plate by SLM in a vacuum was captured by a high-speed video camera. Due to the effects of temperature and scanning speed on the phase transformation, the crystal orientation was evaluated with X-ray diffraction. A phase transformation of the crystal orientation occurred as the baseplate temperature was heated up from 50 to 150 C. (orig.)

  7. Oxide Dissolution and Oxygen Diffusion in Solid-State Recycled Ti-6Al-4V: Numerical Modeling, Verification by Nanoindentation, and Effects on Grain Growth and Recrystallization

    Science.gov (United States)

    Lui, E. W.; Palanisamy, S.; Dargusch, M. S.; Xia, K.

    2017-12-01

    The oxide dissolution and oxygen diffusion during annealing of Ti-6Al-4V solid-state recycled from machining chips by equal-channel angular pressing (ECAP) have been investigated using nanoindentation and numerical modeling. The hardness profile from nanoindentation was converted into the oxygen concentration distribution using the Fleisher and Friedel model. An iterative fitting method was then employed to revise the ideal model proposed previously, leading to correct predictions of the oxide dissolution times and oxygen concentration profiles and verifying nanoindentation as an effective method to measure local oxygen concentrations. Recrystallization started at the prior oxide boundaries where local strains were high from the severe plastic deformation incurred in the ECAP recycling process, forming a band of ultrafine grains whose growth was retarded by solute dragging thanks to high oxygen concentrations. The recrystallized fine-grained region would advance with time to eventually replace the lamellar structure formed during ECAP.

  8. Effect of Molten Pool Size on Microstructure and Tensile Properties of Wire Arc Additive Manufacturing of Ti-6Al-4V Alloy.

    Science.gov (United States)

    Wu, Qianru; Lu, Jiping; Liu, Changmeng; Fan, Hongli; Shi, Xuezhi; Fu, Jie; Ma, Shuyuan

    2017-07-04

    Wire arc additive manufacturing (WAAM) technique is a cost-competitive and efficient technology to produce large structure components in industry domains. Mechanical properties are mainly dominated by the microstructure of the components, which is deeply affected by the molten pool size. In this work, to investigate the effect of the molten pool size on microstructure and mechanical properties of the components, a series of Ti-6Al-4V alloy blocks with different width of molten pool (WMP) ranging from 7 mm to 22 mm were deposited by adjusting the wire feed speed (WFS) from 100 cm/min to 500 cm/min. It is interesting to find that the macrostructure changes from columnar grains to equiaxial grains, and then returns to large columnar grains with the increase of WMP, which is mainly caused by the different cooling rates and thermal gradients. Nonetheless, the tensile properties of the components have a tendency to decline with the increase of WMP.

  9. Influence of damping coefficient from permanent magnets on chatter formation during end milling of titanium alloy (Ti-6Al-4V)

    Science.gov (United States)

    Sulaiman, S. A.; Amin, A. N.

    2015-12-01

    In machining operations, chatter is undesirable due to its adverse effects on the product quality, operation cost, machining accuracy and machine tool life. It is also responsible for reducing output. Chatter is a self-excitation phenomenon occurring in machine tools, in which the cutting process tends to lower the damping capacity of the machine structural components ending in an unstable behavior of the system. Chatter arises due to resonance when the vibrations of the instability of chip formation and the natural vibration modes of the machine-system components coincide. This paper focuses on the influence of damping coefficient from permanent magnets on chip serration frequency as an approach of minimizing chatter in end milling of Titanium alloy (Ti6Al4V). The method consists of two ferrite permanent magnet bars (dimensions: 1" × 6" × 3"), mounted 5mm from the cutting tool using a specially designed fixture which provided a uniform magnetic field of 2500-2700 Gausses. A titanium alloy Ti6Al4V block was then end milled using uncoated WC-Co inserts. A sequence of 15 experimental runs was conducted based on a small Central Composite Design (CCD) model in Response Surface Methodology (RSM). The primary (independent) parameters were: cutting speed, feed, and depth of cut. The data acquisition system comprised a vibration sensor (accelerometer) and a signal conditioning unit was used to measure the vibration data. The resultant vibrations were then analyzed using the DASYLab 5.6 software. Machining tests were conducted for two different conditions - with and without the application of magnets. Scanning Electron Microscope (SEM) was used to measure the chip segmentations. The SEM analysis of chip serrations demonstrated that the chip serration frequency were more stable while cutting under the presence of permanent magnets due to lower intensity of chatter.

  10. Cytocompatibility of Ti-6Al-4V and Ti-5Al-2.5Fe alloys according to three surface treatments, using human fibroblasts and osteoblasts.

    Science.gov (United States)

    Bordji, K; Jouzeau, J Y; Mainard, D; Payan, E; Netter, P; Rie, K T; Stucky, T; Hage-Ali, M

    1996-05-01

    Titanium alloys are well known for their superior mechanical properties as well as for their good biocompatibility, making them desirable as surgical implant materials. However, these alloys have been proven to behave poorly in friction since wear particles were often detected in tissues and organs associated with titanium implants. In this paper, three surface treatments were investigated in order to improve the wear resistance and the hardness of Ti-6Al-4V and Ti-5Al-2.5Fe: (a) glow discharge nitrogen implantation (10(17) atoms cm-2), (b) plasma nitriding by plasma diffusion treatment (PDT) and (c) deposition of TiN layer by plasma-assisted chemical vapour deposition (PACVD) additionally to PDT. Surface characterization after the different treatments showed considerable improvement in surface hardness, especially after the two nitriding processes. Moreover, the good corrosion resistance of untreated alloys was maintained. A cell culture model using human cells was chosen to study the effect of such treatments on the cytocompatibility of these materials. The results showed that Ti-5Al-2.5Fe alloy was as cytocompatible as the Ti-6Al-4V alloy and the same surface treatment led to identical biological consequences on both alloys. Nitrogen implantation did not modify at all the cellular behaviour observed on untreated samples. After the two nitriding treatments, cell proliferation and viability appeared to be significantly reduced and the scanning electron microscopy study revealed somewhat irregular surface states. However, osteoblast phenotype expression and protein synthesis capacity were not affected. PDT and PACVD may be interesting alternatives to the physical vapour deposition technique.

  11. Microstructure and compression properties of 3D powder printed Ti-6Al-4V scaffolds with designed porosity: Experimental and computational analysis.

    Science.gov (United States)

    Barui, Srimanta; Chatterjee, Subhomoy; Mandal, Sourav; Kumar, Alok; Basu, Bikramjit

    2017-01-01

    The osseointegration of metallic implants depends on an effective balance among designed porosity to facilitate angiogenesis, tissue in-growth and bone-mimicking elastic modulus with good strength properties. While addressing such twin requirements, the present study demonstrates a low temperature additive manufacturing based processing strategy to fabricate Ti-6Al-4V scaffolds with designed porosity using inkjet-based 3D powder printing (3DPP). A novel starch-based aqueous binder was prepared and the physico-chemical parameters such as pH, viscosity, and surface tension were optimized for drop-on-demand (DOD) based thermal inkjet printing. Micro-computed tomography (micro-CT) of sintered scaffolds revealed a 57% total porosity in homogeneously porous scaffold and 45% in the gradient porous scaffold with 99% interconnectivity among the micropores. Under uniaxial compression testing, the strength of homogeneously porous and gradient porous scaffolds were ~47MPa and ~90MPa, respectively. The progressive failure in homogeneously porous scaffold was recorded. In parallel to experimental measurements, finite element (FE) analyses have been performed to study the stress distribution globally and also locally around the designed pores. Consistent with FE analyses, a higher elastic modulus was recorded with gradient porous scaffolds (~3GPa) than the homogenously porous scaffolds (~2GPa). While comparing with the existing literature reports, the present work, for the first time, establishes 'direct powder printing methodology' of Ti-6Al-4V porous scaffolds with biomedically relevant microstructural and mechanical properties. Also, a new FE analysis approach, based on the critical understanding of the porous architecture using micro-CT results, is presented to realistically predict the compression response of porous scaffolds. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Improving the tribocorrosion resistance of Ti6Al4V surface by laser surface cladding with TiNiZrO{sub 2} composite coating

    Energy Technology Data Exchange (ETDEWEB)

    Obadele, Babatunde Abiodun, E-mail: obadele4@gmail.com [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Andrews, Anthony [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of Materials Engineering, Kwame Nkrumah University of Science and Technology, Kumasi-Ghana (Ghana); Mathew, Mathew T. [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of orthopedics, Rush University Medical Center, Chicago, IL 60612 (United States); Olubambi, Peter Apata [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Pityana, Sisa [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); National Laser Center, Council for Scientific and Industrial Research, Pretoria (South Africa)

    2015-08-01

    Highlights: • The tribocorrosion behaviour of TiNiZrO{sub 2} composite is investigated. • The effect of ZrO{sub 2} on the microstructure is discussed. • The effect of the combined action of wear and chemical process is reported. • ZrO{sub 2} addition improved the tribocorrosion property of Ti6Al4V. - Abstract: Ti6Al4V alloy was laser cladded with titanium, nickel and zirconia powders in different ratio using a 2 kW CW ytterbium laser system (YLS). The microstructures of the cladded layers were examined using field emission scanning electron microscopy (FESEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). Corrosion and tribocorrosion tests were performed on the cladded surface in 1 M H{sub 2}SO{sub 4} solution. The microstructure revealed the transformation from a dense dendritic structure in TiNi coating to a flower-like structure observed in TiNiZrO{sub 2} cladded layers. There was a significant increase in surface microindentation hardness values of the cladded layers due to the present of hard phase ZrO{sub 2} particles. The results obtained show that addition of ZrO{sub 2} improves the corrosion resistance property of TiNi coating but decreas