Science.gov

Sample records for pure titanium welds

  1. [Effects of laser welding on bond of porcelain fused cast pure titanium].

    PubMed

    Zhu, Juan-fang; He, Hui-ming; Gao, Bo; Wang, Zhong-yi

    2006-04-01

    To investigate the influence of the laser welding on bond of porcelain fused to cast pure titanium. Twenty cast titanium plates were divided into two groups: laser welded group and control group. The low-fusing porcelain was fused to the laser welded cast pure titanium plates at fusion zone. The bond strength of the porcelain to laser welded cast pure titanium was measured by the three-point bending test. The interface of titanium and porcelain was investigated by scanning electron microscopy (SEM) and energy depressive X-ray detector (EDX). The non-welded titanium plates were used as comparison. No significant difference of the bond strength was found between laser-welded samples [(46.85 +/- 0.76) MPa] and the controls [(41.71 +/- 0.55) MPa] (P > 0.05). The SEM displayed the interface presented similar irregularities with a predominance. The titanium diffused to low-fusing porcelain, while silicon and aluminum diffused to titanium basement. Laser welding does not affect low-fusing porcelain fused to pure titanium.

  2. Tensile and flexural strength of commercially pure titanium submitted to laser and tungsten inert gas welds.

    PubMed

    Atoui, Juliana Abdallah; Felipucci, Daniela Nair Borges; Pagnano, Valéria Oliveira; Orsi, Iara Augusta; Nóbilo, Mauro Antônio de Arruda; Bezzon, Osvaldo Luiz

    2013-01-01

    This study evaluated the tensile and flexural strength of tungsten inert gas (TIG) welds in specimens made of commercially pure titanium (CP Ti) compared with laser welds. Sixty cylindrical specimens (2 mm diameter x 55 mm thick) were randomly assigned to 3 groups for each test (n=10): no welding (control), TIG welding (10 V, 36 A, 8 s) and Nd:YAG laser welding (380 V, 8 ms). The specimens were radiographed and subjected to tensile and flexural strength tests at a crosshead speed of 1.0 mm/min using a load cell of 500 kgf applied on the welded interface or at the middle point of the non-welded specimens. Tensile strength data were analyzed by ANOVA and Tukey's test, and flexural strength data by the Kruskal-Wallis test (α=0.05). Non-welded specimens presented significantly higher tensile strength (control=605.84 ± 19.83) (p=0.015) and flexural strength (control=1908.75) (p=0.000) than TIG- and laser-welded ones. There were no significant differences (p>0.05) between the welding types for neither the tensile strength test (TIG=514.90 ± 37.76; laser=515.85 ± 62.07) nor the flexural strength test (TIG=1559.66; laser=1621.64). As far as tensile and flexural strengths are concerned, TIG was similar to laser and could be suitable to replace laser welding in implant-supported rehabilitations.

  3. Evaluation of anodic behavior of commercially pure titanium in tungsten inert gas and laser welds.

    PubMed

    Orsi, Iara Augusta; Raimundo, Larica B; Bezzon, Osvaldo Luiz; Nóbilo, Mauro Antonio de Arruda; Kuri, Sebastião E; Rovere, Carlos Alberto D; Pagnano, Valeria Oliveira

    2011-12-01

    This study evaluated the resistance to corrosion in welds made with Tungsten Inert Gas (TIG) in specimens made of commercially pure titanium (cp Ti) in comparison with laser welds. A total of 15 circular specimens (10-mm diameter, 2-mm thick) were fabricated and divided into two groups: control group-cp Ti specimens (n = 5); experimental group-cp Ti specimens welded with TIG (n = 5) and with laser (n = 5). They were polished mechanically, washed with isopropyl alcohol, and dried with a drier. In the anodic potentiodynamic polarization assay, measurements were taken using a potentiostat/galvanostat in addition to CorrWare software for data acquisition and CorrView for data visualization and treatment. Three curves were made for each working electrode. Corrosion potential values were statistically analyzed by the Student's t-test. Statistical analysis showed that corrosion potentials and passive current densities of specimens welded with TIG are similar to those of the control group, and had lower values than laser welding. TIG welding provided higher resistance to corrosion than laser welding. Control specimens welded with TIG were more resistant to local corrosion initiation and propagation than those with laser welding, indicating a higher rate of formation and growth of passive film thickness on the surfaces of these alloys than on specimens welded with laser, making it more difficult for corrosion to occur. © 2011 by the American College of Prosthodontists.

  4. Microstructural evolution of fusion zone in laser beam welds of pure titanium

    SciTech Connect

    Liu, H.; Nakata, K.; Zhang, J.X.; Yamamoto, N.; Liao, J.

    2012-03-15

    Microstructural evolution of fusion zone in laser beam welds of pure titanium was studied by means of electron backscattering diffraction. The microstructural evolution is strongly affected by the {beta} {yields} {alpha} transformation mechanism dependent on the cooling rate during phase transformation. The long-range diffusional transformation mainly occurs in the fusion zone at the low cooling rate, and the massive transformation dominantly takes place at the high cooling rate. For this reason, the grain morphologies probably change from the granular-like to columnar-like grains with the cooling rate increasing. - Highlights: Black-Right-Pointing-Pointer Microstructures of fusion zone in laser beam welds of pure titanium are studied. Black-Right-Pointing-Pointer Increasing cooling rate changes grain morphology from granular to columnar one. Black-Right-Pointing-Pointer Final microstructures depend on the {beta}{yields}{alpha} transformation mechanisms.

  5. Influence of irradiation conditions on the deformation of pure titanium frames in laser welding.

    PubMed

    Shimakura, Michio; Yamada, Satoshi; Takeuchi, Misao; Miura, Koki; Ikeyama, Joji

    2009-03-01

    Due to its ease of use in connecting metal frames, laser welding is now applied in dentistry. However, to achieve precise laser welding, several problems remain to be resolved. One such problem is the influence of irradiation conditions on the deformation of titanium frameworks during laser welding, which this study sought to investigate. Board-shaped pure titanium specimens were prepared with two different joint types. Two specimens were abutted against each other to form a welding block with gypsum. For welding, three different laser waveforms were used. Deformation of the specimen caused by laser welding was measured as a rise from the gypsum surface at the opposite, free end of the specimen. It was observed that specimens with a beveled edge registered a smaller deformation than specimens with a square edge. In addition, a double laser pulse waveform--whereby a supplementary laser pulse was delivered immediately after the main pulse--resulted in a smaller deformation than with a single laser pulse waveform.

  6. Microstructures of brazings and welds using grade 2 commercially pure titanium.

    PubMed

    Wiskott, H W; Doumas, M T; Scherrer, S S; Susz, C; Belser, U C

    2001-01-01

    Microstructural analyses of commercially pure titanium (CpTi) are scarce. The present report presents the micrographs, fractographs, elemental characteristics, and hardness profiles of brazed joints and weldments using machined rods of CpTi. CpTi rods were joined using four techniques: laser welding, electric-arc welding, electron-beam welding, and gold- and Ti-filler brazing. The specimens were then subjected to tensile and fatigue loading. After sectioning and patterning, optical micrographs of intact joints were obtained. Fractured surfaces were investigated using scanning electron microscopy (SEM). The joint's composition was determined by SEM-energy dispersive x-ray analysis. Hardness was determined at specific locations using a microindenter. While laser welding left the parent metal's equiaxed structure fairly intact, electric-arc welding, electron-beam welding, and brazing created a heat-affected zone in the vicinity of the joint. The extent and characteristics of the heat-affected zone depended on the amount of heat transferred to the specimens. In this respect, brazing essentially increased grain size and altered their shape. Electron-beam welding augmented this phenomenon, yielding grains that encompassed the full diameter of the joint. Electric-arc welding disrupted the granular pattern and generated highly lamellar/acicular structures. Hardness was not a good indicator of mechanical resistance, nor was the joint's structural continuity with the parent substrate. Still, acicular microstructures were characterized by a peculiar behavior in that such joints were highly resistant to tensile stresses while their fatigue strength ranged among the lowest of the joints tested.

  7. Observation and understanding in laser welding of pure titanium at subatmospheric pressure.

    PubMed

    Gao, Ming; Kawahito, Yousuke; Kajii, Shogo

    2017-06-12

    The effects of ambient pressure on the phenomena in laser welding of pure titanium were observed by X-ray transmission in situ apparatus and high speed camera. The penetration depth increased to 18 mm as the ambient pressure decreased to 0.1 kPa. The depth increment from 100 to 0.1 kPa is nearly 200%, far higher than that of mild steel (60%). Both the backward expansion at keyhole tip and the high-speed spatters could be suppressed by decreasing ambient pressure to 1 kPa or lower. The spatter number decreased at least 4 times as the ambient pressure decreased from 10 to 0.1 kPa. It could be deduced that the melt flow decelerated with decreasing ambient pressure. Relevant mechanisms were discussed by the metallic vapor ejection from keyhole and the melt flow types in molten pool.

  8. Element mixing distribution and structure feature of fusion zone in laser welding between different alloys and pure titanium.

    PubMed

    Wu, Haishu; Liu, Jihong; Liu, Xuecheng; Li, Changyi; Yu, Zhiwei

    2002-07-01

    To study micro morphology and element-mixing distribution of different alloys welded in laser and analyze the feasibility of laser welding different alloys. Alloys and titanium were matched into 4 groups: Au-Pt with Ni-Cr; Au-Pt with pure Ti; pure Ti with Ni-Cr; Ni-Cr with Co-Cr. They were welded in laser. Changes in metallography after hybridization of crystalline grain, ranges of heat-affected zone and pores were observed through SEM with ultra-thin windowed X-ray energy atlas. Meanwhile 10 testing points were chosen with area of 300 micro m x 900 micro m along the welding surface from the side A alloy to the side B alloy, than the element mixing distribution and tendency were analyzed with X-ray energy atlas. 1. Hybridization of different alloys: (l) in the group of Au-Pt with Ti, there was titanium element mixing into Au-Pt tissue gradually and evenly on the Au-Pt side of the interface without clear boundary and increasing in size of crystalline grain. However, there was titanium crystalline grain increasing in size, irregular morphology and small sacks on the titanium side with clear boundary. (2) in the group of Ni-Cr with Ti, there was mixing regularly, slow transition and interlocks between crystalline grains on the Ni-Cr side of the in terface. Poor transition, clear boundary and small cracks were observed on titanium side. (3) in the group of Co-Cr with Ni-Cr, there was good transition, obscure boundary on both sides resulting from network, cylinder and branch structure growing. 2. Element-mixing distribution of different alloys. In fusion zone, the metal elements in matched groups mixed well and hybridized into new alloys except titanium blocks. The location of wave peak depended on the composition of alloys. Most of elements were from the alloy far from the fusion zone. The hybridization between pure titanium and any other alloys is not good The effect of laser welding different alloys is ideal except with pure titanium.

  9. Effect of Heat Input on Microstructural Changes and Corrosion Behavior of Commercially Pure Titanium Welds in Nitric Acid Medium

    NASA Astrophysics Data System (ADS)

    Ravi Shankar, A.; Gopalakrishnan, G.; Balusamy, V.; Kamachi Mudali, U.

    2009-11-01

    Commercially pure titanium (Ti) has been selected for the fabrication of dissolver for the proposed fast reactor fuel reprocessing plant at Kalpakkam, India. In the present investigation, microstructural changes and corrosion behavior of tungsten inert gas (TIG) welds of Ti grade-1 and grade-2 with different heat inputs were carried out. A wider heat affected zone was observed with higher heat inputs and coarse grains were observed from base metal toward the weld zone with increasing heat input. Fine and more equiaxed prior β grains were observed at lower heat input and the grain size increased toward fusion zone. The results indicated that Ti grade-1 and grade-2 with different heat inputs and different microstructures were insensitive to corrosion in liquid, vapor, and condensate phases of 11.5 M nitric acid tested up to 240 h. The corrosion rate in boiling liquid phase (0.60-0.76 mm/year) was higher than that in vapor (0.012-0.039 mm/year) and condensate phases (0.04-0.12 mm/year) of nitric acid for Ti grade-1 and grade-2, as well as for base metal for all heat inputs. Potentiodynamic polarization experiment carried out at room temperature indicated higher current densities and better passivation in 11.5 M nitric acid. SEM examination of Ti grade-1 welds for all heat inputs exposed to liquid phase after 240 h showed corrosion attack on the surface, exposing Widmanstatten microstructure containing acicular alpha. The continuous dissolution of the liquid-exposed samples was attributed to the heterogeneous microstructure and non-protective passive film formation.

  10. Sorting Titanium Welding Rods

    NASA Technical Reports Server (NTRS)

    Ross, W. D., Jr.; Brown, R. L.

    1985-01-01

    Three types of titanium welding wires identified by their resistance to current flow. Welding-wire tester quickly identifies unknown titaniumalloy wire by touching wire with test probe, and comparing meter response with standard response. Before touching wire, tip of test probe dipped into an electrolyte.

  11. In-situ spatially resolved x-ray diffraction mapping of the alpha to beta to alpha transformation in commercially pure titanium arc welds

    SciTech Connect

    Elmer, J. W., LLNL

    1998-05-15

    Spatially Resolved X-Ray Diffraction (SRXRD) is used to map the {alpha}{r_arrow}{beta}{r_arrow}{alpha} phase transformation in the heat affected zone (HAZ) of commercially pure titanium gas tungsten arc welds. In-situ SRXRD experiments were conducted on arc welds using a 200 pm diameter x-ray beam at Stanford Synchrotron Radiation Laboratory (SSRL). A map was created which identifies six HAZ microstructural regions that exist between the liquid weld pool and the base metal during welding. The first region is single phase {beta}-Ti that forms in a 2- to 3-mm band adjacent to the liquid weld pool. The second region is back transformed {alpha}-Ti that forms behind the portion of the HAZ where {beta}-Ti was once present at higher temperatures. The third region is completely recrystallized {alpha}-Ti that forms in a 2- to 3-mm band surrounding the single phase {beta}-Ti region. Recrystallized {alpha}-Ti was observed by itself and also with varying amounts of {beta}-Ti. The fourth region of the weld is the partially transformed zone where {alpha}-Ti and {beta}-Ti coexist during welding. The fifth region is directly behind the partially transformed zone and consists of a mixture of recrystallized and back transformed {alpha}-Ti The sixth region is farthest from the weld pool and consists of {alpha}-Ti that is undergoing annealing and recrystallization. Annealing of the base metal was observed to some degree in all of the SRXRD patterns, showing that annealing exceeded 13 mm from the centerline of the weld. Although the microstructure consisted predominantly of {alpha}-Ti, both prior to the weld and after the weld, the (002) texture of the starting material was altered during welding to produce a predominantly (101) texture within the resulting HAZ.

  12. Weld-bonded titanium structures

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Creedon, J. F. (Inventor)

    1976-01-01

    Structurally stronger titanium articles are produced by a weld-bonding technique comprising fastening at least two plates of titanium together using spotwelding and curing an adhesive interspersed between the spot-weld nuggets. This weld-bonding may be employed to form lap joints or to stiffen titanium metal plates.

  13. An Evaluation of Former Soviet Union Welding Processes on Commercially Pure Titanium

    DTIC Science & Technology

    2001-12-01

    wire from Reference 8 is given as 40% to 50% CaF2, 18% to 20% LaF3 or CeF3, 5% to 10% BaF 2, and SrF2 (remainder). No information was available about...of under -fill was observed along the fusion line on each side of the weld metal on Plate A; no under -fill was observed on Plates B and C...and Casting Inspection and Repair for Machinery, Piping, and Pressure Vessels," NAVSEA Technical Publication S9074-AR-GIB-010/278, Washington, DC

  14. Thermal Stir Welds in Titanium

    NASA Astrophysics Data System (ADS)

    Fonda, Richard W.; Knipling, Keith E.; Pilchak, Adam L.

    2016-01-01

    Although conventional friction stir welding (FSW) has proven unsuccessful in joining thick sections of alpha and near-alpha titanium alloys, thermal stir welding, a variant of the FSW process in which an external heat source is used to preheat the workpiece, is demonstrated to be able to reliably join 12.3-mm-thick plates of CP titanium. This paper describes the microstructures and textures that develop in these thermal stir welds. The observed microstructure was used to reconstruct the high-temperature microstructure and texture present during the welding process and therefore reveal the genesis of the welding structures.

  15. Metallurgical effects on titanium by laser welding on dental stone.

    PubMed

    Fujioka, Sonosuke; Kakimoto, Kazutoshi; Inoue, Taro; Okazaki, Joji; Komasa, Yutaka

    2003-12-01

    It is not known for certain that dental stone components influence titanium welding. In this study, we investigated metallurgical problems caused by laser welding on dental stones using wrought commercial pure (CP) titanium. A pulsed Nd:YAG laser irradiated a number of specimens' surfaces which were fixed on either a dental hard stone or a titanium plate. The metallurgical properties of the weld were evaluated using the Vickers hardness test, microstructure observation, fractured surface observation and quantitative analysis of oxygen and hydrogen. In the weld formed on the dental stone there was an increase in hardness, the existence of an acicular structure and a brittle fractured surface, and an increase in the oxygen and hydrogen concentrations compared with base metal. In the weld formed on the titanium plate, these changes were not observed. Therefore, it was demonstrated that laser welding on dental stones made the welds brittle.

  16. Welded Permanent Fittings for Titanium Hydraulic Tubing.

    DTIC Science & Technology

    FITTINGS, *HYDRAULIC EQUIPMENT, RIVETED JOINTS, TITANIUM ALLOYS, PIPES , JET TRANSPORT AIRCRAFT, COLD WORKING, PRESSURE, RUPTURE, ARC WELDING , INERT...GAS WELDING , RADIOGRAPHY, STRESS RELIEVING, SUPERSONIC AIRCRAFT, COMMERCIAL AIRCRAFT.

  17. Submerged Arc Welding of Titanium.

    DTIC Science & Technology

    1978-09-30

    AD-AOB5 400 MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF MATERIA -ETC F/G 11/6 SUBMERGED ARC WELDING OF TITANIUM.(U) UCSEP 18 G HUNTER, 6 B KENNEY, M...3. RECIPIENT’S CATALOG NUMW-- TITLE (and Subtitle) n or QnQMED Submerged Arc Welding of Tianu Technal epor o. 9? ji’ G./ Huntert’G. KenneybM Ring...nuinbor) Welding , Titanium, Fluxes, Oxygen, Nitrogen ASS40qAfC ,,(AA.K 20. A9 AT(Continue an revereet side It necessay and Identify by block numabor) 0

  18. Temporarily alloying titanium to facilitate friction stir welding

    SciTech Connect

    Hovanski, Yuri

    2009-05-01

    While historically hydrogen has been considered an impurity in titanium, when used as a temporary alloying agent it promotes beneficial changes to material properties that increase the hot-workability of the metal. This technique known as thermohydrogen processing was used to temporarily alloy hydrogen with commercially pure titanium sheet as a means of facilitating the friction stir welding process. Specific alloying parameters were developed to increase the overall hydrogen content of the titanium sheet ranging from commercially pure to 30 atomic percent. Each sheet was evaluated to determine the effect of the hydrogen content on process loads and tool deformation during the plunge phase of the friction stir welding process. Two materials, H-13 tool steel and pure tungsten, were used to fabricate friction stir welding tools that were plunged into each of the thermohydrogen processed titanium sheets. Tool wear was characterized and variations in machine loads were quantified for each tool material and weld metal combination. Thermohydrogen processing was shown to beneficially lower plunge forces and stabilize machine torques at specific hydrogen concentrations. The resulting effects of hydrogen addition to titanium metal undergoing the friction stir welding process are compared with modifications in titanium properties documented in modern literature. Such comparative analysis is used to explain the variance in resulting process loads as a function of the initial hydrogen concentration of the titanium.

  19. [Dental welding titanium and its clinical usage].

    PubMed

    Li, H; Xiao, M; Zhao, Y

    1998-09-01

    Due to its excellent biocompatibility, desirable chemical and mechanical properties, Titanium has been used for implant denture, RPD and FPD, where welding techniques were indispensable. This paper introduces 5 useful modern ways to weld Titanium and their clinical usage. They are: laser, plasma welding, TIG, infraned brazing and Hruska electrowelding.

  20. Improved diffusion welding and roll welding of titanium alloys

    NASA Technical Reports Server (NTRS)

    Holko, K. H.

    1973-01-01

    Auto-vacuum cleaning technique was applied to titanium parts prior to welding. This provides oxide-free welding surfaces. Diffusion welding can be accomplished in as little as five minutes of hot pressing. Roll welding can be accomplished with only ten percent deformation.

  1. Weld-brazing of titanium

    NASA Technical Reports Server (NTRS)

    Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

    1974-01-01

    A joining process, designated weld-brazing, which combines resistance spotwelding and brazing has been developed at the NASA Langley Research Center. Resistance spot-welding is employed to position and align the parts and to establish a suitable faying surface gap for brazing; it contributes to the integrity of the joint. Brazing enhances the properties of the joint and reduces the stress concentrations normally associated with spotwelds. Ti-6Al-4V titanium alloy joints have been fabricated using 3003 aluminum braze both in a vacuum furnace and in a retort containing an inert gas environment.

  2. Weld-brazing of titanium

    NASA Technical Reports Server (NTRS)

    Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

    1974-01-01

    A joining process, designated weld-brazing, which combines resistance spotwelding and brazing has been developed at the NASA Langley Research Center. Resistance spot-welding is employed to position and align the parts and to establish a suitable faying surface gap for brazing; it contributes to the integrity of the joint. Brazing enhances the properties of the joint and reduces the stress concentrations normally associated with spotwelds. Ti-6Al-4V titanium alloy joints have been fabricated using 3003 aluminum braze both in a vacuum furnace and in a retort containing an inert gas environment.

  3. Comparative analysis of the fit of 3-unit implant-supported frameworks cast in nickel-chromium and cobalt-chromium alloys and commercially pure titanium after casting, laser welding, and simulated porcelain firings.

    PubMed

    Tiossi, Rodrigo; Rodrigues, Renata Cristina Silveira; de Mattos, Maria da Glória Chiarello; Ribeiro, Ricardo Faria

    2008-01-01

    This study compared the vertical misfit of 3-unit implant-supported nickel-chromium (Ni-Cr) and cobalt-chromium (Co-Cr) alloy and commercially pure titanium (cpTi) frameworks after casting as 1 piece, after sectioning and laser welding, and after simulated porcelain firings. The results on the tightened side showed no statistically significant differences. On the opposite side, statistically significant differences were found for Co-Cr alloy (118.64 microm [SD: 91.48] to 39.90 microm [SD: 27.13]) and cpTi (118.56 microm [51.35] to 27.87 microm [12.71]) when comparing 1-piece to laser-welded frameworks. With both sides tightened, only Co-Cr alloy showed statistically significant differences after laser welding. Ni-Cr alloy showed the lowest misfit values, though the differences were not statistically significantly different. Simulated porcelain firings revealed no significant differences.

  4. Customized orbital welding meets the challenge of titanium welding

    SciTech Connect

    1996-12-01

    Titanium has emerged as the material of choice for tubing used in surface condensers around the world in both new and retrofit configurations. A major worldwide supplier of steam surface condensers to the electric utility industry, Senior Engineering is finding an increased use of titanium tubes and tube sheets in condenser specifications. When compared to other alloys, titanium`s light weight is efficient in design, handling, transportation and installation activities. Additionally, it maintains a stable price structure. Senior Engineering implements an orbital welding process using fusion gas tungsten arc welding (GTAW) for its titanium tube-to-tube sheet welding. Orbital welding involves the use of a welding apparatus placed inside a tube or pipe to automatically and precisely weld a 360-deg joint. When welding manually, a welder stops several times during the weld due to the large amount of time and fatigue involved in achieving 360-deg welds, which results in lack of fusion. An automated orbital welding system, however, can accomplish the task as one continuous weld. This reduces process time and decreases lack of fusion. The orbital welding systems, featuring a microprocessor-based controller, an inverter-based power supply, an expandable mandrel and a customized torch shroud, reduced welding labor by 35%. The improved labor efficiency justified the addition of two more of the systems in January 1996.

  5. Welding and Joining of Titanium Aluminides

    PubMed Central

    Cao, Jian; Qi, Junlei; Song, Xiaoguo; Feng, Jicai

    2014-01-01

    Welding and joining of titanium aluminides is the key to making them more attractive in industrial fields. The purpose of this review is to provide a comprehensive overview of recent progress in welding and joining of titanium aluminides, as well as to introduce current research and application. The possible methods available for titanium aluminides involve brazing, diffusion bonding, fusion welding, friction welding and reactive joining. Of the numerous methods, solid-state diffusion bonding and vacuum brazing have been most heavily investigated for producing reliable joints. The current state of understanding and development of every welding and joining method for titanium aluminides is addressed respectively. The focus is on the fundamental understanding of microstructure characteristics and processing–microstructure–property relationships in the welding and joining of titanium aluminides to themselves and to other materials. PMID:28788113

  6. Welding and Joining of Titanium Aluminides.

    PubMed

    Cao, Jian; Qi, Junlei; Song, Xiaoguo; Feng, Jicai

    2014-06-25

    Welding and joining of titanium aluminides is the key to making them more attractive in industrial fields. The purpose of this review is to provide a comprehensive overview of recent progress in welding and joining of titanium aluminides, as well as to introduce current research and application. The possible methods available for titanium aluminides involve brazing, diffusion bonding, fusion welding, friction welding and reactive joining. Of the numerous methods, solid-state diffusion bonding and vacuum brazing have been most heavily investigated for producing reliable joints. The current state of understanding and development of every welding and joining method for titanium aluminides is addressed respectively. The focus is on the fundamental understanding of microstructure characteristics and processing-microstructure-property relationships in the welding and joining of titanium aluminides to themselves and to other materials.

  7. Welding of titanium and nickel alloy by combination of explosive welding and spark plasma sintering technologies

    SciTech Connect

    Malyutina, Yu. N. Bataev, A. A. Shevtsova, L. I.; Mali, V. I. Anisimov, A. G.

    2015-10-27

    A possibility of titanium and nickel-based alloys composite materials formation using combination of explosive welding and spark plasma sintering technologies was demonstrated in the current research. An employment of interlayer consisting of copper and tantalum thin plates makes possible to eliminate a contact between metallurgical incompatible titanium and nickel that are susceptible to intermetallic compounds formation during their interaction. By the following spark plasma sintering process the bonding has been received between titanium and titanium alloy VT20 through the thin powder layer of pure titanium that is distinguished by low defectiveness and fine dispersive structure.

  8. Yttria Nanoparticle Reinforced Commercially Pure (CP) Titanium

    DTIC Science & Technology

    2011-09-01

    nanoparticles as well as titanium boride (TiB) reinforcements were produced through gas atomization. After consolidation and extrusion, room temperature...pure FE iron O oxygen Ti titanium TiB titanium boride TYS tensile yield strength UTS ultimate tensile strength wt% weight percent Y2O3

  9. Weld bonding of titanium with polyimide adhesives

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Sheppard, C. H.; Orell, M. K.

    1975-01-01

    A conductive adhesive primer and a capillary flow adhesive were developed for weld bonding titanium alloy joints. Both formulations contained ingredients considered to be non-carcinogenic. Lap-shear joint test specimens and stringer-stiffened panels were weld bonded using a capillary flow process to apply the adhesive. Static property information was generated for weld bonded joints over the temperature range of 219K (-65 F) to 561K (550 F). The capillary flow process was demonstrated to produce weld bonded joints of equal strength to the weld through weld bonding process developed previously.

  10. Welding of gamma titanium aluminide alloys

    NASA Technical Reports Server (NTRS)

    Smashey, Russell W. (Inventor); Kelly, Thomas J. (Inventor); Snyder, John H. (Inventor); Sheranko, Ronald L. (Inventor)

    1998-01-01

    An article made of a gamma titanium aluminide alloy is welded, as for example in the weld repair of surface cracks, by removing foreign matter from the area to be welded, first stress relieving the article, cooling the entire article to a welding temperature of from about 1000.degree. F. to about 1400.degree. F., welding a preselected region in an inert atmosphere at the welding temperature, and second stress relieving the article. Welding is preferably accomplished by striking an arc in the preselected region so as to locally melt the alloy in the preselected region, providing a filler metal having the same composition as the gamma titanium aluminide alloy of the article, and feeding the filler metal into the arc so that the filler metal is melted and fused with the article to form a weldment upon solidification.

  11. Method for producing titanium aluminide weld rod

    DOEpatents

    Hansen, Jeffrey S.; Turner, Paul C.; Argetsinger, Edward R.

    1995-01-01

    A process for producing titanium aluminide weld rod comprising: attaching one end of a metal tube to a vacuum line; placing a means between said vacuum line and a junction of the metal tube to prevent powder from entering the vacuum line; inducing a vacuum within the tube; placing a mixture of titanium and aluminum powder in the tube and employing means to impact the powder in the tube to a filled tube; heating the tube in the vacuum at a temperature sufficient to initiate a high-temperature synthesis (SHS) reaction between the titanium and aluminum; and lowering the temperature to ambient temperature to obtain a intermetallic titanium aluminide alloy weld rod.

  12. Polyimide weld bonding for titanium alloy joints

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Kurland, R. M.

    1974-01-01

    Two weld bonding processes were developed for joining titanium alloy; one process utilizes a weld-through technique and the other a capillary-flow technique. The adhesive used for the weld-through process is similar to the P4/A5F system. A new polyimide laminating resin, BFBI/BMPM, was used in the capillary-flow process. Static property information was generated for weld-bonded joints over the temperature range of 219 K (-65 F) to 561 K (+550 F) and fatigue strength information was generated at room temperature. Significant improvement in fatigue strength was demonstrated for weld-bonded joints over spot-welded joints. A demonstration was made of the applicability of the weld-through weld-bonding process for fabricating stringer stiffened skin panels.

  13. Metallurgy and deformation of electron beam welded similar titanium alloys

    NASA Astrophysics Data System (ADS)

    Pasang, T.; Sabol, J. C.; Misiolek, W. Z.; Mitchell, R.; Short, A. B.; Littlefair, G.

    2012-04-01

    Butt welded joins were produced between commercially pure titanium and various titanium alloys using an electron beam welding technique. The materials used represent commercially pure grade, α-β alloy and β alloy. They were CP Ti, Ti-6Al-4V (Ti64) and Ti-5Al-5V-5Mo-3Cr (Ti5553), respectively. Grains were largest in the FZs of the different weldments, decreasing in size towards the heat affected zones (HAZs) and base metals. Hardness measurements taken across the traverse cross-sections of the weldments were constant from base metal-to-weld-to-base metal for CP Ti/CP Ti and Ti64/Ti64 welds, while the FZ of Ti5553/Ti5553 had a lower hardness compared with the base metal. During tensile testing the CP Ti/CP Ti weldments fractured at the base metal, whereas both the Ti64/Ti64 and Ti5553/Ti5553 broke at the weld zones. Fracture surface analysis suggested microvoid coalescence as the failure mechanism. The compositional analysis showed a relatively uniform distribution of solute elements from base metal-to-weld-to-base metal. CP Ti has always been known for its excellent weldability, Ti64 has good weldability and, preliminary results indicated that Ti5553 alloy is also weldable.

  14. Polyimide adhesives for weld-bonding titanium

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Sheppard, C. H.; Baucom, R.

    1976-01-01

    Two weld bonding processes were developed for joining titanium alloy; one process utilizes a weld-through technique and the other a capillary-flow technique. The adhesive used for the weld-through process is similar to the P4/A5F system and a new adhesive system, CP/CFA, was used in the capillary-flow process. Static property information was generated for weld-bonded joints over the temperature range of 219K (-65 F) to 561K (550 F) and fatigue strength information was generated at room temperature. Significant improvement in fatigue strength was demonstrated for weld-bonded joints over spot-welded joints. A demonstration was made of the applicability of weld-bonding for fabricating stringer stiffened skin panels.

  15. Mechanical properties of thin films of laser-welded titanium and their associated welding defects.

    PubMed

    Wu, Yulu; Xin, Haitao; Zhang, Chunbao; Tang, Zhongbin; Zhang, Zhiyuan; Wang, Weifeng

    2014-11-01

    The aim of this study was to evaluate the mechanical properties of thin films of laser-welded cast titanium using an interference strain/displacement gauge (ISDG) and to analyze factors that affect laser welding. Dog-bone-shaped small specimens of cast titanium were prepared by wire cutting after they were laser-welded. The specimens were divided into three groups according to the gap distance of the laser weld; the control was non-welded titanium. Small specimens without cast defects detected by X-ray screening were measured by a tensile test machine using ISDG, and stress-strain curves were drawn. Finally, the fracture texture was analyzed. The ultimate tensile strengths (UTSs) of specimens with a gap distance of 0.00, 0.25, and 0.50 mm were 492.16 ± 33.19, 488.09 ± 43.18, and 558.45 ± 10.80 MPa, respectively. There were no significant differences in UTS between the test groups and the control group (p > 0.05). However, the plastic deformation and the percent elongation increased as the gap distance increased. Incomplete penetration defects appeared in groups that had small gap distances, which may have affected the properties of the laser-welded titanium. However, the welding material was still pure titanium. These results suggest that an appropriate gap distance should be maintained to improve the application of dental laser welding.

  16. Formation of vortices during explosion welding (titanium-orthorhombic titanium aluminide)

    NASA Astrophysics Data System (ADS)

    Rybin, V. V.; Greenberg, B. A.; Antonova, O. V.; Elkina, O. A.; Ivanov, M. A.; Inozemtsev, A. V.; Patselov, A. M.; Sidorov, I. I.

    2009-10-01

    The possibility of cladding commercially pure titanium by a plate of orthorhombic titanium aluminide has been investigated. The bimetallic joints of orthorhombic titanium aluminide (Ti-30Al-16Nb-1Zr-1Mo) with commercially pure titanium have been obtained by explosion welding. It has been found that the weld joint investigated had a multilayer structure consisting of a zone of continuous deformation observed in both materials, a zone of titanium recrystallization, and a transition zone near the interface. Wave formation and formation of isolated vortex zones have been observed. It has been found that upon explosion welding the bonding of the surfaces is effected via melting and subsequent mixing (in the zone of vortices) and the transfer of particles of one metal into another with the formation of particle tracks (outside the zone of vortices). A possible scenario of the formation of the vortex zone in the melt with a subsequent eutectic decomposition is proposed. The structure of the vortex zones was found to consist of an ultrafine mixture of α and β grains (both phases are disordered) with the grain size changing in the limits of 50-300 nm. The regions of transition from the vortex zone to the region of continuous deformation of the aluminide and to the recrystallized zone of titanium have been investigated.

  17. Laser-TIG Welding of Titanium Alloys

    NASA Astrophysics Data System (ADS)

    Turichin, G.; Tsibulsky, I.; Somonov, V.; Kuznetsov, M.; Akhmetov, A.

    2016-08-01

    The article presents the results of investigation the technological opportunity of laser-TIG welding of titanium alloys. The experimental stand for implementation of process with the capability to feed a filler wire was made. The research of the nature of transfer the filler wire into the welding pool has been demonstrated. The influence of distance between the electrode and the surface of the welded plates on the stability of the arc was shown. The relationship between welding velocity, the position of focal plane of the laser beam and the stability of penetration of plates was determined.

  18. Dynamics of near-alpha titanium welding

    NASA Astrophysics Data System (ADS)

    Neuberger, Brett William

    Typically, when gas tungsten arc welding (GTAW) is employed to join near-alpha titanium alloys, the resulting weld fusion zone (FZ) is much harder than that of the base metal (BM), thereby leading to lost ductility. The aim of this investigation was to improve FZ ductility of Ti-5Al-1Sn-1V-1Zr-0.8Mo by modifying filler metal chemistry. In this regard, metallic yttrium was added to the filler metal and aluminum concentration reduced. It was believed that additions of yttrium would lead to formation of yttria in the weld melt, thereby promoting heterogeneous nucleation. Since oxygen and aluminum both act as alpha-stabilizers, expected pickup of oxygen during the welding process will be offset by the aluminum reduction. Tensile testing indicated that modified filler metal welds showed a dramatic increase in ductility of the FZ. Fracture toughness testing showed that while JIC values decreased in all welds, the tearing modulus, T, in modified filler metal welds was significantly higher than that of matching filler metal welds. Microhardness mapping of the weld zones illustrated that modified filler metal welds were significantly softer than matching filler metal welds. Microstructural examinations were completed through the use of optical, SEM and TEM studies, indicating that there was a presence of nano-particles in the weld FZ. XPS analysis identified these particles as yttrium oxysulfate. WDS analysis across the welds' heat affected zones demonstrated that there is an internal diffusion of oxygen from the BM into the FZ. Research results indicate yttrium oxysulfide particles form in the weld pool, act as a drag force on the solidification front and limit growth of prior-beta grain boundaries. The reduced prior-beta grain size and removal of interstitial oxygen from the matrix in modified filler metal welds, further enhanced by oxidation of yttrium oxysulfide to yttrium oxysulfate, leads to increased ductility in the weld's FZ. Addition of yttrium to the weld also

  19. Structure of the welding zone between titanium and orthorhombic titanium aluminide for explosion welding: I. Interface

    NASA Astrophysics Data System (ADS)

    Rybin, V. V.; Grinberg, B. A.; Ivanov, M. A.; Kuz'min, S. V.; Lysak, V. I.; Elkina, O. A.; Patselov, A. M.; Inozemtsev, A. V.; Antonova, O. V.; Kozhevnikov, V. E.

    2011-10-01

    The structures of the interfaces and transition zones of bimetallic metal-intermetallide joints produced by explosion welding under various conditions have been studied. The welded materials were commercial-purity titanium and orthorhombic titanium aluminide of two alloying schemes. The specific features of the structure and substructure of the zones under study are discussed. Wave formation and formation of isolated vortex zones, as well as tracks of particles related to the transfer of particles of one metal into the other one, were observed. A possible scenario of formation of interfaces, depending on the composition of titanium aluminide and welding conditions, is proposed.

  20. Electron Beam Welding to Join Gamma Titanium Aluminide Articles

    NASA Technical Reports Server (NTRS)

    Kelly, Thomas Joseph (Inventor)

    2008-01-01

    A method is provided for welding two gamma titanium aluminide articles together. The method includes preheating the two articles to a welding temperature of from about 1700 F to about 2100 F, thereafter electron beam welding the two articles together at the welding temperature and in a welding vacuum to form a welded structure, and thereafter annealing the welded structure at an annealing temperature of from about 1800 F to about 2200 F, to form a joined structure.

  1. Joint strength of laser-welded titanium.

    PubMed

    Liu, J; Watanabe, I; Yoshida, K; Atsuta, M

    2002-03-01

    The objective of this study was to examine the joint strength of titanium laser-welding using several levels of laser output energy [current (A)]. Cast titanium plates (0.5 x 3.0 x 40 and 1.0 x 3.0 x 40 mm(3)) were prepared and perpendicularly cut at the center of the plate. After the cut halves were fixed in a jig, they were laser-welded using a Nd: YAG laser at several levels of output energy in increments of 30A from 180 to 300A. The penetration depths of laser to titanium were measured under various conditions for output energy, pulse duration, and spot diameter to determine the appropriate conditions for these parameters. Based on the correlation between the results obtained for penetration depth and the size of the specimens (thickness: 0.5 and 1.0 mm, width: 3.0 mm), the pulse duration and spot diameter employed in this study were 10 ms and 1.0 mm, respectively. Three laser pulses (spot diameter: 1.0 mm) were applied from one side to weld the entire joint width (3.0 mm) of the specimens. Uncut specimens served as the non-welded control specimens. Tensile testing was conducted at a crosshead speed of 2 mm/min and a gage length of 10 mm. The breaking force (N) was recorded, and the data (n=5) were statistically analyzed. For the 0.5 mm thick specimens, the breaking force of the specimens laser-welded at currents of 240, 270, and 300A were not statistically (P>0.05) different from the non-welded control specimens. There were no significant differences in breaking force among the 1.0mm thick specimens laser-welded at currents of 270 and 300A, and the non-welded control specimens. Under appropriate conditions, joint strengths similar to the strength of the non-welded parent metal were achieved.

  2. SST Technology Follow-On Program, Phase I. Titanium Alloy Welding.

    DTIC Science & Technology

    JET TRANSPORT AIRCRAFT, *AIRFRAMES, *TITANIUM ALLOYS, WELDING , INERT GAS WELDING , ARC WELDING , ELECTRON BEAM WELDING , FATIGUE(MECHANICS), DEFECTS...MATERIALS), WELDS , WELDABILITY, STRESSES, STRESS RELIEVING, SPECIFICATIONS, MAINTENANCE, THERMAL STRESSES, ALUMINUM ALLOYS, VANADIUM ALLOYS, SUPERSONIC AIRCRAFT.

  3. [Studies on application of pure titanium for cast plate].

    PubMed

    Sakai, M

    1990-06-01

    Pure titanium produced by a commercial pure titanium casting system was studied for use as a cast plate for clinical application. The mechanical properties, elemental analysis, castability, adaptability of pure titanium and adhesion to denture base resin were investigated. The interfacial zone of the pure titanium castings was composed of a layered structure obtained by reaction with phosphate bonded Al2O3/SiO2 investment material. Vicher's hardness at 100 microns thick from the surface was higher than that in the inner part by oxidation. Cast pure titanium showed tensile strength, elongation and hardness close to those of the type III or IV dental gold alloy. The castability of pure titanium was lower than that of Co-Cr alloy and pure titanium castings also had large casting defects. Adaptability between pure titanium cast plate and the working model was satisfactory when reversible hydrocolloid impression material was used with heating-bath treatment in the refractory model. The tensile and compressive shear bonding strength of pure titanium to heat-curing or self-curing resin were similar to that of the Co-Cr alloy, and surface treatment using a solution containing 2-vol% 3-methacryloxypropyltrimethoxysilane produced a higher bonding strength than non-treatment, MKV treatment and 4-META treatment. These findings suggest that pure titanium castings produced by this system have suitable mechanical properties, adaptability and adhesion to denture base resin, and is available for cast plate in clinical application.

  4. Causal Factors of Weld Porosity in Gas Tungsten Arc Welding of Powder Metallurgy Produced Titanium Alloys

    SciTech Connect

    Muth, Thomas R; Yamamoto, Yukinori; Frederick, David Alan; Contescu, Cristian I; Chen, Wei; Lim, Yong Chae; Peter, William H; Feng, Zhili

    2013-01-01

    ORNL undertook an investigation using gas tungsten arc (GTA) welding on consolidated powder metallurgy (PM) titanium (Ti) plate, to identify the causal factors behind observed porosity in fusion welding. Tramp element compounds of sodium and magnesium, residual from the metallothermic reduction of titanium chloride used to produce the titanium, were remnant in the starting powder and were identified as gas forming species. PM-titanium made from revert scrap where sodium and magnesium were absent, showed fusion weld porosity, although to a lesser degree. We show that porosity was attributable to hydrogen from adsorbed water on the surface of the powders prior to consolidation. The removal / minimization of both adsorbed water on the surface of titanium powder and the residues from the reduction process prior to consolidation of titanium powders, are critical to achieve equivalent fusion welding success similar to that seen in wrought titanium produced via the Kroll process.

  5. Microstructural characterization and hardness properties of electric resistance welding titanium joints for dental applications.

    PubMed

    Ceschini, Lorella; Boromei, Iuri; Morri, Alessandro; Nardi, Diego; Sighinolfi, Gianluca; Degidi, Marco

    2015-06-01

    The electric resistance welding procedure is used to join a titanium bar with specific implant abutments in order to produce a framework directly in the oral cavity of the patient. This investigation studied the effects of the welding process on microstructure and hardness properties of commercially pure (CP2 and CP4) Ti components. Different welding powers and cooling procedures were applied to bars and abutments, normally used to produce the framework, in order to simulate the clinical intraoral welding procedure. The analyses highlighted that the joining process did not induce appreciable changes in the geometry of the abutments. However, because of unavoidable microstructural modifications in the welded zones, the hardness decreased to values lower than those of the unwelded CP2 and CP4 Ti grades, irrespective of the welding environments and parameters.

  6. Narrow groove welding of titanium using the hot-wire gas tungsten arc process

    SciTech Connect

    Crement, D.J. )

    1993-04-01

    From this study of automatic gas tungsten arc welding of commercially pure titanium, the following may be concluded: (1) automatic cold-wire GTAW and automatic hot-wire GTAW may be used to weld titanium in the open without contamination from the atmosphere when proper shielding is used; (2) automatic hot-wire GTAW exhibits substantial reductions in transverse weld shrinkage, as compared to manual GTAW; (3) increased deposition rates can be achieved with hot-wire additions to automatic gas tungsten arc welding; (4) automatic cold-wire GTAW and automatic hot-wire GTAW may be used with narrow groove joint designs; (5) direct viewing of the arc may be used to aid in torch placement and wire entry position.

  7. Mechanical and structural characteristics of commercially pure grade 2 Ti welds and solder joints.

    PubMed

    Anselm Wiskott, H W; Doumas, T; Scherrer, S S; Belser, U C; Susz, C

    2001-08-01

    This study aimed at determining whether data previously gathered for a laser welds and IR brazings using a Au-Pd alloy were applicable to titanium joints. As to its resistance under fatigue loading, Au-Pd alloy had shown a poor response to pre-ceramic laser welding and post-ceramic brazing. The present study was designed to assess the mechanical resistance, the microstructure and the elemental diffusion of laser welded, electric arch welded and brazed joints using commercially pure titanium as substrate metal. Mechanical resistance was determined by determining the joints' ultimate tensile strength and their resistance to fatigue loading. Elemental diffusion to and from the joints was assessed using microprobe tracings. Optical micrographs of the joints were also obtained and evaluated. Under monotonic tensile stress, three groups emerged: (1) the GTAW and the native (i.e. as received) substrate, (2) the annealed substrate and the laser welds and (3) the brazed joints. Under fatigue stress, the order was: first the native and annealed substrate, second the brazings and laser welds, third the GTAW joints. No Au-filler brazing withstood the applied fatigue loading. The micrographs showed various patterns, an absence of HAZ cracking and several occurrences of Widmanstätten structures. Elemental diffusion to and from the Ti substrate was substantial in the Ti filler brazings and virtually nil in the Au-based brazings. Under fatigue stress application, the titanium-based brazings as well as the laser- and electric arc welds performed equally well if not better than a previously tested AuPd alloy. There was a definite increase in grain size with increased heat application. However, no feature of the microstructures observed or the elemental analysis could be correlated with the specimen's resistance to fatigue stress application. Copyright 2001 Kluwer Academic Publishers

  8. A Review of Titanium Welding Processes.

    DTIC Science & Technology

    1986-02-03

    Welding ( GTAW )............................. 2 jPlasma Arc Welding (PAW) ................................... 3 Gas Metal Arc Welding (GMAW...earliest use of gas tungsten arc welding ( GTAW ). Submerged arc welding (SAW) was introduced in 1944 (p.149(4)). Gas metal arc welding (GMAW) was developed...discussion. Gas Tungsten Arc Welding GTAW )" The GTAW process is due to the heating from an arc between a noncon- sumable tungsten electrode and the work

  9. Friction Stir Welding of Aluminum and Titanium Alloys

    DTIC Science & Technology

    2007-11-02

    What is this? Jata/US Air Force Typical FSW Tools W-Re tool in collet- style tool holder. Used for welding steels and Ti alloys 3-piece self...Friction Stir Welding of Aluminum and Titanium alloys NATO Advanced Research Workshop Metallic Materials with High Structural Efficiency Kyiv...valid OMB control number. 1. REPORT DATE 18 MAR 2004 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Friction Stir Welding of Aluminum

  10. CO2 laser welding of titanium aluminide intermetallic compound

    NASA Astrophysics Data System (ADS)

    Kuwahara, Gaku; Yamaguchi, Shigeru; Nanri, Kenzo; Ootani, Masanori; Seto, Sachio; Arai, Mikiya; Fujioka, Tomoo

    2000-02-01

    Titanium aluminide intermetallic compound is studied to find out good welding conditions using CO2 laser irradiation. In the experiment, we used the casting titanium aluminide containing iron, vanadium and boron with a thickness of 2 mm. We carried out bead-on-plate laser welding at various initial temperatures of specimens varied from room temperature to 873 [K] in inert gas environment filled with argon. We measured fused depth, bead width and Vickers hardness. As a result of experiments, welding speeds that allow full bead-on- plate welding to be possible were strongly by dependent on the initial temperature, 3000 [mm/min], initial temperature 873 [K], 2600 [mm/mm], initial temperature 673 [K], and 2000 [mm/min] with 300 [K]. Transverse crack-free welding was achieved, when initial temperature was at 873 [K].

  11. Disk Laser Weld Brazing of AW5083 Aluminum Alloy with Titanium Grade 2

    NASA Astrophysics Data System (ADS)

    Sahul, Miroslav; Sahul, Martin; Vyskoč, Maroš; Čaplovič, Ľubomír; Pašák, Matej

    2017-03-01

    Disk laser weld brazing of dissimilar metals was carried out. Aluminum alloy 5083 and commercially pure titanium Grade 2 with the thickness of 2.0 mm were used as experimental materials. Butt weld brazed joints were produced under different welding parameters. The 5087 aluminum alloy filler wire with a diameter of 1.2 mm was used for joining dissimilar metals. The elimination of weld metal cracking was attained by offsetting the laser beam. When the offset was 0 mm, the intermixing of both metals was too high, thus producing higher amount of intermetallic compounds (IMCs). Higher amount of IMCs resulted in poorer mechanical properties of produced joints. Grain refinement in the fusion zone occurred especially due to the high cooling rates during laser beam joining. Reactions at the interface varied in the dependence of its location. Continuous thin IMC layer was observed directly at the titanium-weld metal interface. Microhardness of an IMC island in the weld metal reached up to 452.2 HV0.1. The XRD analysis confirmed the presence of tetragonal Al3Ti intermetallic compound. The highest tensile strength was recorded in the case when the laser beam offset of 300 μm from the joint centerline toward aluminum alloy was utilized.

  12. Effect of laser welding on the titanium ceramic tensile bond strength

    PubMed Central

    GALO, Rodrigo; RIBEIRO, Ricardo Faria; RODRIGUES, Renata Cristina Silveira; PAGNANO, Valéria de Oliveira; de MATTOS, Maria da Glória Chiarello

    2011-01-01

    Titanium reacts strongly with elements, mainly oxygen at high temperature. The high temperature of titanium laser welding modifies the surface, and may interfere on the metal-ceramic tensile bond strength. Objective The influence of laser welding on the titanium-ceramic bonding has not yet been established. The purpose of this in vitro study was to analyze the influence of laser welding applied to commercially pure titanium (CpTi) substructure on the bond strength of commercial ceramic. The influence of airborne particle abrasion (Al2O3) conditions was also studied. Material and Methods Forty CpTi cylindrical rods (3 mm x 60 mm) were cast and divided into 2 groups: with laser welding (L) and without laser welding (WL). Each group was divided in 4 subgroups, according to the size of the particles used in airborne particle abrasion: A - Al2O3 (250 µm); B - Al2O3 (180 µm); C - Al2O3 (110 µm); D - Al2O3 (50 µm). Ceramic rings were fused around the CpTi rods. Specimens were invested and their tensile strength was measured at fracture with a universal testing machine at a crosshead speed of 2.0 mm/min and 200 kgf load cell. Statistical analysis was carried out with analysis of variance and compared using the independent t test (p≤0.05). Results Significant differences were found among all subgroups (p<0.05). The highest and the lowest bond strength means were recorded in subgroups WLC (52.62 MPa) and LD (24.02 MPa), respectively. Conclusion Airborne particle abrasion yielded significantly lower bond strength as the Al2O3 particle size decreased. Mechanical retention decreased in the laser-welded specimens, i.e. the metal-ceramic tensile bond strength was lower. PMID:21956585

  13. Effect of laser welding on the titanium ceramic tensile bond strength.

    PubMed

    Galo, Rodrigo; Ribeiro, Ricardo Faria; Rodrigues, Renata Cristina Silveira; Pagnano, Valéria de Oliveira; Mattos, Maria da Glória Chiarello de

    2011-08-01

    Titanium reacts strongly with elements, mainly oxygen at high temperature. The high temperature of titanium laser welding modifies the surface, and may interfere on the metal-ceramic tensile bond strength. The influence of laser welding on the titanium-ceramic bonding has not yet been established. The purpose of this in vitro study was to analyze the influence of laser welding applied to commercially pure titanium (CpTi) substructure on the bond strength of commercial ceramic. The influence of airborne particle abrasion (Al2O3) conditions was also studied. Forty CpTi cylindrical rods (3 mm x 60 mm) were cast and divided into 2 groups: with laser welding (L) and without laser welding (WL). Each group was divided in 4 subgroups, according to the size of the particles used in airborne particle abrasion: A - Al2O3 (250 µm); B - Al2O3 (180 µm); C - Al2O3 (110 µm); D - Al2O3 (50 µm). Ceramic rings were fused around the CpTi rods. Specimens were invested and their tensile strength was measured at fracture with a universal testing machine at a crosshead speed of 2.0 mm/min and 200 kgf load cell. Statistical analysis was carried out with analysis of variance and compared using the independent t test (p<0.05). Significant differences were found among all subgroups (p<0.05). The highest and the lowest bond strength means were recorded in subgroups WLC (52.62 MPa) and LD (24.02 MPa), respectively. Airborne particle abrasion yielded significantly lower bond strength as the Al2O3 particle size decreased. Mechanical retention decreased in the laser-welded specimens, i.e. the metal-ceramic tensile bond strength was lower.

  14. Feasibility study of consolidation by direct compaction and friction stir processing of commercially pure titanium powder

    NASA Astrophysics Data System (ADS)

    Nichols, Leannah M.

    Commercially pure titanium can take up to six months to successfully manufacture a six-inch in diameter ingot in which can be shipped to be melted and shaped into other useful components. The applications to the corrosion-resistant, light weight, strong metal are endless, yet so is the manufacturing processing time. At a cost of around $80 per pound of certain grades of titanium powder, the everyday consumer cannot afford to use titanium in the many ways it is beneficial simply because the number of processing steps it takes to manufacture consumes too much time, energy, and labor. In this research, the steps it takes from the raw powder form to the final part are proposed to be reduced from 4-8 steps to only 2 steps utilizing a new technology that may even improve upon the titanium properties at the same time as it is reducing the number of steps of manufacture. The two-step procedure involves selecting a cylindrical or rectangular die and punch to compress a small amount of commercially pure titanium to a strong-enough compact for transportation to the friction stir welder to be consolidated. Friction stir welding invented in 1991 in the United Kingdom uses a tool, similar to a drill bit, to approach a sample and gradually plunge into the material at a certain rotation rate of between 100 to 2,100 RPM. In the second step, the friction stir welder is used to process the titanium powder held in a tight holder to consolidate into a harder titanium form. The resulting samples are cut to expose the cross section and then grinded, polished, and cleaned to be observed and tested using scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), and a Vickers microhardness tester. The results were that the thicker the sample, the harder the resulting consolidated sample peaking at 2 to 3 times harder than that of the original commercially pure titanium in solid form at a peak value of 435.9 hardness and overall average of 251.13 hardness. The combined

  15. Analysis and Characterization of the Role of Ni Interlayer in the Friction Welding of Titanium and 304 Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Muralimohan, C. H.; Ashfaq, M.; Ashiri, Rouholah; Muthupandi, V.; Sivaprasad, K.

    2016-01-01

    Joining of commercially pure Ti to 304 stainless steel by fusion welding processes possesses problems due to the formation of brittle intermetallic compounds in the weld metal, which degrade the mechanical properties of the joints. Solid-state welding processes are contemplated to overcome these problems. However, intermetallic compounds are likely to form even in Ti-SS joints produced with solid-state welding processes such as friction welding process. Therefore, interlayers are employed to prevent the direct contact between two base metals and thereby mainly to suppress the formation of brittle Ti-Fe intermetallic compounds. In the present study, friction-welded joints between commercially pure titanium and 304 stainless steel were obtained using a thin nickel interlayer. Then, the joints were characterized by optical microscopy, scanning electron microscopy, energy dispersive spectrometry, and X-ray diffractometry. The mechanical properties of the joints were evaluated by microhardness survey and tensile tests. Although the results showed that the tensile strength of the joints is even lower than titanium base metal, it is higher than that of the joints which were produced without nickel interlayer. The highest hardness value was observed at the interface between titanium and nickel interlayers indicating the formation of Ni-Ti intermetallic compounds. Formation these compounds was validated by XRD patterns. Moreover, in tensile tests, fracture of the joints occurred along this interface which is related to its brittle nature.

  16. Causal Factors of Weld Porosity in Gas Tungsten Arc Welding of Powder-Metallurgy-Produced Titanium Alloys

    NASA Astrophysics Data System (ADS)

    Muth, T. R.; Yamamoto, Y.; Frederick, D. A.; Contescu, C. I.; Chen, W.; Lim, Y. C.; Peter, W. H.; Feng, Z.

    2013-05-01

    An investigation was undertaken using gas tungsten arc (GTA) welding on consolidated powder metallurgy (PM) titanium (Ti) plate to identify the causal factors behind observed porosity in fusion welding. Tramp element compounds of sodium and magnesium, residual from the metallothermic reduction of titanium chloride used to produce the titanium, were remnant in the starting powder and were identified as gas-forming species. PM-titanium made from revert scrap, where sodium and magnesium were absent, showed fusion weld porosity, although to a lesser degree. We show that porosity was attributable to hydrogen from adsorbed water on the surface of the powders prior to consolidation. The removal and minimization of both adsorbed water on the surface of titanium powder and the residues from the reduction process prior to consolidation of titanium powders are critical for achieving equivalent fusion welding success similar to that seen in wrought titanium produced via the Kroll process.

  17. Structure of the welding zone between titanium and orthorhombic titanium aluminide for explosion welding: II. Local melting zones

    NASA Astrophysics Data System (ADS)

    Grinberg, B. A.; Ivanov, M. A.; Rybin, V. V.; Kuz'min, S. V.; Lysak, V. I.; Elkina, O. A.; Patselov, A. M.; Antonova, O. V.; Inozemtsev, A. V.

    2011-10-01

    The structure and chemical composition of the local melting zones that form during explosion welding of orthorhombic titanium aluminide with commercial-purity titanium near a wavy interface between them are studied. The Rayleigh number is estimated to propose a possible mechanism for the formation of a concentric structure in these zones. Titanium aluminide fragments are detected near the zone boundaries. It is assumed that the fragmentation in the transition zone is caused by the division of a material into loosely coupled microvolumes under the action of a strong external action in a time comparable with the explosion time. Outside the transition zone, fragmentation occurs via a traditional way beginning from dislocation accumulation. Both processes occur in titanium aluminide and only one process (banded structure formation) takes place in titanium.

  18. Laser welding of an advanced rapidly-solidified titanium alloy

    NASA Astrophysics Data System (ADS)

    Baeslack, W. A., III; Chiang, S.; Albright, C. A.

    1990-06-01

    The laser weldability of a complex RS titanium alloy containing yttrium is investigated by evaluating comparatively the microstructures, mechanical properties, and fracture characteristics of the base metal and the rapidly solidified weld fusion zone. To prevent atmospheric contamination the specimen was enclosed in a helium-purged plastic bag during the welding process. After welding, the coupons were sectioned transverse to the laser beam direction of traverse, epoxy mounted, polished down to 0.05 micron SiO2 and etched with Kroll's reagent for examination utilizing light and SEM and energy-dispersive X-ray analysis. Results indicate that laser welding is effective in producing a fine fusion zone dispersoid structure in the RS Ti composite.

  19. Fracture Behaviour of Nickel-Titanium Laser Welded Joints

    NASA Astrophysics Data System (ADS)

    Maletta, C.; Falvo, A.; Furgiuele, F.; Barbieri, G.; Brandizzi, M.

    2009-08-01

    In this study, the effects of Nd:YAG laser welding on the fracture behavior of Ni-rich nickel-titanium sheets are analyzed by experimental investigations. The welding was carried out in open air conditions by using a special shielding/clamping system to avoid the chemical contamination of the molten zone and the formation of hot cracks. Mechanical tests of standard dog bone-shaped and single edge crack specimens were carried out to measure the stress-strain response and the fracture resistance of both the base and the welded materials. Furthermore, scanning electron microscopy observations of the fracture surfaces were carried out in order to better understand the failure mechanisms. Finally, systematic comparative studies between base and laser-welded materials were carried out.

  20. Inverse Thermal Analysis of Titanium GTA Welds Using Multiple Constraints

    NASA Astrophysics Data System (ADS)

    Lambrakos, S. G.; Shabaev, A.; Huang, L.

    2015-06-01

    Inverse thermal analysis of titanium gas-tungsten-arc welds using multiple constraint conditions is presented. This analysis employs a methodology that is in terms of numerical-analytical basis functions for inverse thermal analysis of steady-state energy deposition in plate structures. The results of this type of analysis provide parametric representations of weld temperature histories that can be adopted as input data to various types of computational procedures, such as those for prediction of solid-state phase transformations. In addition, these temperature histories can be used to construct parametric function representations for inverse thermal analysis of welds corresponding to other process parameters or welding processes whose process conditions are within similar regimes. The present study applies an inverse thermal analysis procedure that provides for the inclusion of constraint conditions associated with both solidification and phase transformation boundaries.

  1. Weld-brazing of titanium. [resistance spot welding combined with brazing

    NASA Technical Reports Server (NTRS)

    Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

    1973-01-01

    A joining process, designated weld-brazing, which combines resistance spot-welding and brazing has been developed at the NASA Langley Research Center. Resistance spot-welding is employed to position and aline the parts and to establish a suitable faying surface gap for brazing and contributes to the integrity of the joint. Brazing enhances the properties of the joint and reduces the stress concentrations normally associated with spotwelds. Ti-6Al-4V titanium alloy joints have been fabricated using 3003 aluminum braze both in a vaccum furnace and in a retort containing an inert gas environment.

  2. Weld-brazing of titanium. [resistance spot welding combined with brazing

    NASA Technical Reports Server (NTRS)

    Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

    1973-01-01

    A joining process, designated weld-brazing, which combines resistance spot-welding and brazing has been developed at the NASA Langley Research Center. Resistance spot-welding is employed to position and aline the parts and to establish a suitable faying surface gap for brazing and contributes to the integrity of the joint. Brazing enhances the properties of the joint and reduces the stress concentrations normally associated with spotwelds. Ti-6Al-4V titanium alloy joints have been fabricated using 3003 aluminum braze both in a vaccum furnace and in a retort containing an inert gas environment.

  3. Effect of titanium preoxidation on wrought pure titanium to ceramic bond strength.

    PubMed

    Zhang, Cui-cui; Ye, Jian-tao; Zhang, Yi-ping; Liao, Juan-kun; Li, Bo-hua

    2013-02-01

    The creation of high bond strength between machined computer-manufactured pure titanium and porcelain remains a problem. However, machined titanium does not form the thick titanium oxide film found in cast titanium. The purpose of this study was to investigate the effects of different preoxidation treatments on the bond strength of a machined pure titanium ceramic system. Specimens of commercially pure titanium (25 × 3 × 0.5 mm) were divided equally into 6 groups (n=8), which received different preoxidation treatments (3 hour natural oxidation; 600°C, 650°C, 700°C, 750°C, and 800°C for 3 minutes). Bond strengths were evaluated by using a 3-point bend test. The results were analyzed by using 1-way ANOVA and the least significant difference test. Twelve additional specimens of commercially pure titanium (15 × 3 × 0.5 mm) were cut for interface observation and divided equally into 6 groups that received the preoxidation treatments described previously. Scanning electron microscopy and energy dispersive spectrum were used to observe microscopic features of the interface between Ti and ceramic. The bond strength values of the 6 groups ranged from 23.72 ±2.53 MPa to 36.99 ±3.92 MPa, with significant differences (P<.05). The specimen that received 750°C preoxidation had the highest bond strength. The main interface elements of the 6 groups were O, Si, Ti, Sn, Al, Na, and K. Ti showed a sigmoidal diffusion curve in each group, and Si showed a sigmoidal diffusion curve in most groups. Sn was enriched in each group's interface. Preoxidation under vacuum before porcelain firing can effectively improve the bond strength of machined pure titanium-porcelain systems. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  4. Tribological evaluation of diamond coating on pure titanium in comparison with plasma nitrided titanium and uncoated titanium

    SciTech Connect

    Yan, B.; Loh, N.L.; Fu, Y.; Sun, C.Q.; Hing, P.

    1999-12-01

    Titanium alloys are characterized by poor tribological properties, and the traditional use of titanium alloys has been restricted to nontribological applications. The deposition of a well adherent diamond coating is a promising way to solve this problem. In this study, the tribological properties of diamond-coated titanium were studied using a pin-on-disk tribometer, and the results were compared with those of pure titanium and plasma nitrided titanium. The tribological behavior of pure titanium was characterized by high coefficient of friction and rapid wear of materials. Plasma nitriding improved the wear resistance only under low normal load; however, this hardened layer was not efficient in improving the wear resistance and the friction properties under high normal load. Diamond coating on pure titanium improved the wear resistance of titanium significantly. Surface profilometry measurement indicated that little or no wear of the diamond coating occurred under the test conditions loads. The roughness of the diamond coating was critical because it controlled the amount of abrasive damage on the counterface. Reducing the surface roughness by polishing led to the reductions in both the friction and wear of the counterface.

  5. Laser welding technique for titanium alloy sheet

    SciTech Connect

    Gobbi, S.L.; Zhang, L.; Norris, J.; Zolotovsky, S.; Richter, K.H.

    1994-12-31

    In order to achieve reliable welds with minimal distortion for the fabrication of aerospace industrial components, several techniques were carried out on Ti6Al4V and Ti6Al2Sn4Zr2Mo sheets of 1.6 mm and 2 mm thickness using a CO{sub 2} and a Nd-YAG laser. Test 1: A satisfactory weld can be obtained by using a CO{sub 2} CW laser with a filler wire. Test 2: Before laser welding the edges were shaped with a special relief defined incorporated filler, which allows it to avoid the classical filler wire. Test 3: A cosmetic butt weld without filler, obtained by defocusing the CO{sub 2} CW laser beam, enables it to eliminate the undercut and result in a smooth surface. Test 4: High power pulsed Nd-YAG laser equipped with fiber optics and f5{prime} focus lens was employed, which produces the autogenous butt welds with full penetration and regular bead profile. The undercut and slump could be controlled by pulse energy, pulse duration, frequency, waveform and overlapping rate.

  6. Study of Gravity Effects on Titanium Laser Welding in the Vertical Position.

    PubMed

    Chang, Baohua; Yuan, Zhang; Pu, Haitao; Li, Haigang; Cheng, Hao; Du, Dong; Shan, Jiguo

    2017-09-08

    To obtain satisfactory welds in positional laser beam welding, it is necessary to know how process parameters will influence the quality of welds in different welding positions. In this study, the titanium alloy Ti6Al4V sheets were laser welded in two vertical welding positions (vertical up and vertical down), and the appearance, porosity, strength, and ductility of the laser joints were evaluated. Results show that undercuts of the vertical up welds were greater than that of vertical down welds, while the porosity contents were much higher in vertical down welds than that in vertical up welds. When welding with a higher heat input, the vertical up welding position resulted in poor weld profiles (undercuts and burn-through holes), whereas the vertical down welding position led to excessive porosity contents in welds. Both severe undercut and excessive porosity were detrimental to the tensile properties of the welds. Weld appearance was improved and porosity contents were reduced by using a lower heat input, achieving better weld quality. Therefore, it is suggested that process parameter settings with relatively high laser powers and welding speeds, which can result in lower heat inputs, are used when laser welding the Ti6Al4V titanium alloys vertically.

  7. Study of Gravity Effects on Titanium Laser Welding in the Vertical Position

    PubMed Central

    Yuan, Zhang; Pu, Haitao; Li, Haigang; Cheng, Hao; Du, Dong; Shan, Jiguo

    2017-01-01

    To obtain satisfactory welds in positional laser beam welding, it is necessary to know how process parameters will influence the quality of welds in different welding positions. In this study, the titanium alloy Ti6Al4V sheets were laser welded in two vertical welding positions (vertical up and vertical down), and the appearance, porosity, strength, and ductility of the laser joints were evaluated. Results show that undercuts of the vertical up welds were greater than that of vertical down welds, while the porosity contents were much higher in vertical down welds than that in vertical up welds. When welding with a higher heat input, the vertical up welding position resulted in poor weld profiles (undercuts and burn-through holes), whereas the vertical down welding position led to excessive porosity contents in welds. Both severe undercut and excessive porosity were detrimental to the tensile properties of the welds. Weld appearance was improved and porosity contents were reduced by using a lower heat input, achieving better weld quality. Therefore, it is suggested that process parameter settings with relatively high laser powers and welding speeds, which can result in lower heat inputs, are used when laser welding the Ti6Al4V titanium alloys vertically. PMID:28885573

  8. Effect of laser welding on the titanium composite tensile bond strength.

    PubMed

    Galo, Rodrigo; Ribeiro, Ricardo Faria; Rodrigues, Renata Cristina Silveira; Pagnano, Valéria de Oliveira; de Mattos, Maria da Glória Chiarello

    2009-01-01

    The aim of this study was to analyze the shear bond strength between commercially pure titanium, with and without laser welding, after airbone-particle abrasion (Al(2)O(3)) and 2 indirect composites. Sixty-four specimens were cast and divided into 2 groups with and without laser welding. Each group was divided in 4 subgroups, related to Al(2)O(3) grain size: A - 250 microm; B - 180 microm; C- 110 microm; and D - 50 microm. Composite rings were formed around the rods and light polymerized using UniXS unit. Specimens were invested and their shear bond strength at failure was measured with a universal testing machine at a crosshead speed of 2.0 mm/min. Statistical analysis was carried out with ANOVA and Tukey's test (alpha=0.05). The highest bond strength means were recorded in 250 microm group without laser welding. The lowest shear bond strength means were recorded in 50 microm group with laser welding. Statistically significant differences (p<0.05) were found between all groups. In conclusion, airborne particle abrasion yielded significantly lower bond strength as the Al(2)O(3) particle size decreased. Shear bond strength decreased in the laser welded specimens.

  9. Weld-brazing - a new joining process. [combination resistance spot welding and brazing of titanium alloys

    NASA Technical Reports Server (NTRS)

    Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

    1972-01-01

    A joining process designated weld brazing which combines resistance spot welding and brazing has been developed. Resistance spot welding is used to position and align the parts as well as to establish a suitable faying surface gap for brazing. Fabrication is then completed by capillary flow of the braze alloy into the joint. The process has been used successfully to fabricate Ti-6Al-4V titanium alloy joints using 3003 aluminum braze alloy. Test results obtained on single overlap and hat-stiffened structural specimens show that weld brazed joints are superior in tensile shear, stress rupture, fatigue, and buckling than joint fabricated by spotwelding or brazing. Another attractive feature of the process is that the brazed joints is hermetically sealed by the braze material.

  10. Experimental and simulation study on the microstructure of TA15 titanium alloy laser beam welded joints

    NASA Astrophysics Data System (ADS)

    Zhan, Xiaohong; Peng, Qingyu; Wei, Yanhong; Ou, Wenmin

    2017-09-01

    Laser beam welding technique offers obvious advantages over other fusion welding processes in terms of joining titanium alloy. The microstructure of welded seam and heat affected zone resulted from diverse welding speeds and laser powers were investigated after simulating welding heat treatment. The analysis of the thermal transport properties successfully explained the morphology. Optimal process parameters were obtained. The simulation results were consistent with the corresponding experimental observations.

  11. On the Hydrogen Embrittlement of Commercially Pure Alpha Titanium: An Example from the Petrochemical Industry

    NASA Astrophysics Data System (ADS)

    Tawancy, H. M.

    2017-02-01

    Grade 2 of commercially pure Ti consisting of α-phase has many applications in the petrochemical industry such as floaters of gauges used to indicate liquid levels in tanks and reaction vessels. A floater fabricated by welding of 3.5-mm-thick sheet of grade 2 Ti into a thick-walled cylinder to indicate the level of a liquid mixture of isobutane, neobutane and neopentane in a petrochemical plant has lost its structural integrity by puncturing, cracking and blistering particularly at the section in contact with the liquid. The damage has been most severe in the base metal adjacent to the weld. Detailed microstructural characterization of the damaged floater and unwelded section of the same material has been carried out using scanning electron microscopy combined with energy dispersive spectroscopy, x-ray diffraction and transmission electron microscopy, and the results have been complemented by stress analysis and microhardness measurements. It is shown that the mechanical strength of the floater has been degraded by a combination of excessive absorption of hydrogen during welding and rapid cooling from the β-phase field aided by the stresses generated by the liquid pressure. Absorption of hydrogen and rapid cooling are found to alter the desirable morphology of equiaxed grains of α-phase into a multi-phase structure with fine platelet-type morphology. The base metal adjacent to the weld is found to contain the brittle δ-phase of titanium hydride in a low-ductility matrix of α-Ti with some β-Ti. However, β-Ti is found to be the predominant constituent of the weld.

  12. On the Hydrogen Embrittlement of Commercially Pure Alpha Titanium: An Example from the Petrochemical Industry

    NASA Astrophysics Data System (ADS)

    Tawancy, H. M.

    2016-12-01

    Grade 2 of commercially pure Ti consisting of α-phase has many applications in the petrochemical industry such as floaters of gauges used to indicate liquid levels in tanks and reaction vessels. A floater fabricated by welding of 3.5-mm-thick sheet of grade 2 Ti into a thick-walled cylinder to indicate the level of a liquid mixture of isobutane, neobutane and neopentane in a petrochemical plant has lost its structural integrity by puncturing, cracking and blistering particularly at the section in contact with the liquid. The damage has been most severe in the base metal adjacent to the weld. Detailed microstructural characterization of the damaged floater and unwelded section of the same material has been carried out using scanning electron microscopy combined with energy dispersive spectroscopy, x-ray diffraction and transmission electron microscopy, and the results have been complemented by stress analysis and microhardness measurements. It is shown that the mechanical strength of the floater has been degraded by a combination of excessive absorption of hydrogen during welding and rapid cooling from the β-phase field aided by the stresses generated by the liquid pressure. Absorption of hydrogen and rapid cooling are found to alter the desirable morphology of equiaxed grains of α-phase into a multi-phase structure with fine platelet-type morphology. The base metal adjacent to the weld is found to contain the brittle δ-phase of titanium hydride in a low-ductility matrix of α-Ti with some β-Ti. However, β-Ti is found to be the predominant constituent of the weld.

  13. Grain fragmentation in ultrasonic-assisted TIG weld of pure aluminum.

    PubMed

    Chen, Qihao; Lin, Sanbao; Yang, Chunli; Fan, Chenglei; Ge, Hongliang

    2017-11-01

    Under the action of acoustic waves during an ultrasonic-assisted tungsten inert gas (TIG) welding process, a grain of a TIG weld of aluminum alloy is refined by nucleation and grain fragmentation. Herein, effects of ultrasound on grain fragmentation in the TIG weld of aluminum alloy are investigated via systematic welding experiments of pure aluminum. First, experiments involving continuous and fixed-position welding are performed, which demonstrate that ultrasound can break the grain of the TIG weld of pure aluminum. The microstructural characteristics of an ultrasonic-assisted TIG weld fabricated by fixed-position welding are analyzed. The microstructure is found to transform from plane crystal, columnar crystal, and uniform equiaxed crystal into plane crystal, deformed columnar crystal, and nonuniform equiaxed crystal after application of ultrasound. Second, factors influencing ultrasonic grain fragmentation are investigated. The ultrasonic amplitude and welding current are found to have a considerable effect on grain fragmentation. The degree of fragmentation first increases and then decreases with an increase in ultrasonic amplitude, and it increases with an increase in welding current. Measurement results of the vibration of the weld pool show that the degree of grain fragmentation is related to the intensity of acoustic nonlinearity in the weld pool. The greater the intensity of acoustic nonlinearity, the greater is the degree of grain fragmentation. Finally, the mechanism of ultrasonic grain fragmentation in the TIG weld of pure aluminum is discussed. A finite element simulation is used to simulate the acoustic pressure and flow in the weld pool. The acoustic pressure in the weld pool exceeds the cavitation threshold, and cavitation bubbles are generated. The flow velocity in the weld pool does not change noticeably after application of ultrasound. It is concluded that the high-pressure conditions induced during the occurrence of cavitation, lead to grain

  14. FLUXES FOR MECHANIZED ELECTRIC WELDING,

    DTIC Science & Technology

    WELDING FLUXES, WELDING ), (* WELDING , WELDING FLUXES), ARC WELDING , WELDS, STABILITY, POROSITY, WELDING RODS, STEEL, CERAMIC MATERIALS, FLUXES(FUSION), TITANIUM ALLOYS, ALUMINUM ALLOYS, COPPER ALLOYS, ELECTRODEPOSITION

  15. Effect of casting methods on castability of pure titanium.

    PubMed

    Takahashi, J; Zhang, J Z; Okazaki, M

    1993-12-01

    Two types of patterns were tested for castability: 1) polyester mesh pattern (20mm x 22mm with 100 open squares) and 2) 20mm x 20mm wax plates 1.0 and 1.5 mm in thickness. These materials were invested using a pre-arranged commercial phosphate-bonded investment for titanium. Three different types of casting machines were selected: 1) a pressure-type casting machine with separate melting and casting chambers, 2) a pressure-type casting machine with one chamber and 3) a centrifugal-type casting machine at 3000 rpm. Pure titanium (> 99.5%) was cast into the molds at a mold temperature of 100 degrees C. The castability of mesh pattern was evaluated in terms of the number of cast segment, and the cast plate was evaluated using X-ray transparent images by a digital imaging technique. The centrifugal casting method showed the best castability among these three casting methods.

  16. Joining titanium materials with tungsten inert gas welding, laser welding, and infrared brazing.

    PubMed

    Wang, R R; Welsch, G E

    1995-11-01

    Titanium has a number of desirable properties for dental applications that include low density, excellent biocompatibility, and corrosion resistance. However, joining titanium is one of the practical problems with the use of titanium prostheses. Dissolved oxygen and hydrogen may cause severe embrittlement in titanium materials. Therefore the conventional dental soldering methods that use oxygen flame or air torch are not indicated for joining titanium materials. This study compared laser, tungsten inert gas, and infrared radiation heating methods for joining both pure titanium and Ti-6Al-4V alloy. Original rods that were not subjected to joining procedures were used as a control method. Mechanical tests and microstructure analysis were used to evaluate joined samples. Mechanical tests included Vickers microhardness and uniaxial tensile testing of the strength of the joints and percentage elongation. Two-way analysis of variance and Duncan's multiple range test were used to compare mean values of tensile strength and elongation for significant differences (p < or = 0.05). Tensile rupture occurred in the joint region of all specimens by cohesive failure. Ti-6Al-4V samples exhibited significantly greater tensile strength than pure titanium samples. Samples prepared by the three joining methods had markedly lower tensile elongation than the control titanium and Ti-6Al-4V rods. The changes in microstructure and microhardness were studied in the heat-affected and unaffected zones. Microhardness values increased in the heat-affected zone for all the specimens tested.

  17. Radiographic inspection of porosity in pure titanium dumbbell castings.

    PubMed

    Nuñez, Juliana Maria Costa; Takahashi, Jessica Mie Ferreira Koyama; Henriques, Guilherme Elias Pessanha; Nóbilo, Mauro Antônio de Arruda; Consani, Rafael Leonardo Xediek; Mesquita, Marcelo Ferraz

    2011-09-01

    Titanium frameworks are frequently indicated for implant supported prostheses; however, voids are usually encountered inside cast titanium.   This study aimed to confirm the efficacy of a radiographic technique for inspection of porosity in commercially pure titanium castings with different diameter.   Sixty dumbbell rods (n=20) with a central 1.5, 2.0 and 3.5mm diameter were prepared by lost-wax casting. Cast specimens were finished and polished and submitted to radiographic examination (90kV, 15mA, 0.6s and 10-13mm of distance) using periapical film. The radiographs were visually analysed for the presence of porosity in the extension of the dumbbell or in the central portion of the rods. Data were submitted to Pearson Chi-square test (5%).   The tested radiographic method proved to be suitable for the evaluation of cast frameworks. Internal porosities were observed in most of the specimens (91.7%) (p=0.0005); however, only 20% occurred on the central portion of the rods (p=0.612).   Internal porosities can be visualised through radiographs and occur mostly in small diameter structures. The radiographic evaluation of metal structures can improve the quality of frameworks and thereby potentially increase the longevity of the rehabilitation. © 2010 The Gerodontology Society and John Wiley & Sons A/S.

  18. Joining characteristics of titanium-based orthodontic wires connected by laser and electrical welding methods.

    PubMed

    Matsunaga, Junko; Watanabe, Ikuya; Nakao, Noriko; Watanabe, Etsuko; Elshahawy, Waleed; Yoshida, Noriaki

    2015-01-01

    This study investigated the possibility of electrical and laser welding to connect titanium-based alloy (beta-titanium and nickel-titanium) wires and stainless-steel or cobalt-chromium alloy wires for fabrication of combination arch-wires. Four kinds of straight orthodontic rectangular wires (0.017 × 0.025 inch) were used: stainless-steel (S-S), cobalt-chromium (Co-Cr), beta-titanium alloy (β-Ti), and nickel-titanium (Ni-Ti). Homogeneous and heterogeneous end-to-end joints (15 mm long each) were made by electrical welding and laser welding. Non-welded wires (30 mm long) were also used as a control. Maximum loads at fracture (N) and elongation (%) were measured by conducting tensile test. The data (n = 10) were statistically analyzed using analysis of variance/Tukey test (P < 0.05).The S-S/S-S and Co-Cr/Co-Cr specimens showed significantly higher values of the maximum load (ML) at fracture and elongation (EL) than those of the Ni-Ti/Ni-Ti and β-Ti/β-Ti specimens for electrical welding and those of the S-S/S-S and Co-Cr/Co-Cr specimens welded by laser. On the other hand, the laser-welded Ni-Ti/Ni-Ti and β-Ti/β-Ti specimens exhibited higher values of the ML and EL compared to those of the corresponding specimens welded by electrical method. In the heterogeneously welded combinations, the electrically welded Ni-Ti/S-S, β-Ti/S-S and β-Ti/Co-Cr specimens showed significantly (P < 0.05) higher ML and EL than those of the corresponding specimens welded by laser. Electrical welding exhibited the higher values of maximum load at fracture and elongation for heterogeneously welded combinations than laser-welding.

  19. Tailoring properties of commercially pure titanium by gradation extrusion

    NASA Astrophysics Data System (ADS)

    Bergmann, Markus; Rautenstrauch, Anja; Selbmann, René; de Oliveira, Raoni Barreto; Coelho, Rodrigo Santiago; Landgrebe, Dirk

    2016-10-01

    Commercially pure titanium (CP Ti) is of great importance in medical applications due to its attractive properties, such as high biocompatibility, excellent corrosion resistance and relatively low density and suitable stiffness. Compared to the commonly used Ti-6Al-4V alloy, its lower strength has to be increased. The most attractive approach is to subject CP Ti to severe plastic deformation (SPD) processes such as Equal Channel Angular Pressing (ECAP). The resulting decreased grain size in CP Ti yields a significant increase in hardness and strength. Common SPD-processes typically provide a uniform modification of the material. Their material efficiency and productivity are critical and limiting factors. A new approach is to tailor the material properties by using Gradation Extrusion, which produces a distinct gradient in microstructure and strength. The forming process combines a regular impact extrusion process and severe plastic deformation in the lateral area of the material. This efficient process can be integrated easily into forming process chains, for instance for dental implants. This paper presents the forming process and the applied die geometry. The results of numerical simulations are used to illustrate the potential of the process to modify and strengthen the titanium material. Experiments show that the material is successfully processed by gradation extrusion. By characterizing the hardness and its distribution within the formed parts the effects of the process are investigated.

  20. Repairing an implant titanium milled framework using laser welding technology: a clinical report.

    PubMed

    Prasad, Soni; Monaco, Edward A

    2009-04-01

    The application of laser welding technology allows titanium to be welded predictably and precisely to achieve accurate fit of a milled framework. Laser energy results in localized heat production, thereby reducing thermal expansion. Unlike soldering, laser energy can be directed to a small area, making it possible to laser weld close to acrylic resin or ceramic. This article describes the use of laser welding to repair an implant titanium milled fixed denture. A quick, cost-effective, accurate repair was accomplished, and the repaired framework possessed adequate strength and the same precise fit as the original framework.

  1. [Evaluation of clinical efficacy of casting pure titanium ring on reparation of subgingival residual root].

    PubMed

    Huang, Lei; Wang, Peng

    2013-10-01

    To explore treatment regime and curative effect of the casting pure titanium ring on reparation of subgingival residual root. Thirty-two teeth were selected for reparation of subgingival residual root after root canal therapy in our department during 2008-2010. The teeth were restored with casting pure titanium ring, glass fiber post and all-ceramic crown. The patients were recalled 12 and 24 months after placement of the pure titanium ring. Gingival crevicular fluid(GCF) samples were collected by filter paper strips. Then the weight of GCF was detected and the gingival index was recorded. The data was analyzed for paired samples t test by SPSS17.0 software package. There was no significant difference in the weight of GCF and the gingival index before and after placement of pure titanium ring (P<0.05). By using pure titanium ring, most subgingival residual root after root canal therapy can be rehabilitated and function well for long time.

  2. Latent Cracking of Tantalum-Titanium Welds Due to Hydrogen Embrittlement

    NASA Astrophysics Data System (ADS)

    Hossick-Schott, Joachim; Reiterer, Markus; Heffelfinger, Jason; Hintz, Mike; Ringle, Mike; Levina, Iryna; Gaffney, Kevin

    2013-05-01

    Establishing electrical interconnects in implantable electronic medical devices frequently requires joining of dissimilar materials. A weld between a tantalum wire and titanium sheet metal on a contact module is presented as an example for dissimilar joining. Latent, brittle cracking was observed in the proximity of the weld upon pull testing. The weld cracking occurs by the mechanism known as hydrogen stress cracking (HSC) and is due to titanium hydride formation. Diffusion facilitated hydrogen transport into the weld area. Diffusing hydrogen accumulates preferably in regions of high stress, causing latent titanium hydride formation and embrittlement of the weld. A broad array of analytical tools such as scanning electron microscopy (SEM), transmission electron microscopy, electron backscattered diffraction, dynamic secondary ion mass spectroscopy, and nanoindentation were utilized to identify the root cause for HSC.

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

    SciTech Connect

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

    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.

  4. Comparative study of two commercially pure titanium casting methods

    PubMed Central

    RODRIGUES, Renata Cristina Silveira; FARIA, Adriana Claudia Lapria; ORSI, Iara Augusta; de MATTOS, Maria da Gloria Chiarello; MACEDO, Ana Paula; RIBEIRO, Ricardo Faria

    2010-01-01

    The interest in using titanium to fabricate removable partial denture (RPD) frameworks has increased, but there are few studies evaluating the effects of casting methods on clasp behavior. Objective This study compared the occurrence of porosities and the retentive force of commercially pure titanium (CP Ti) and cobalt-chromium (Co-Cr) removable partial denture circumferential clasps cast by induction/centrifugation and plasma/vacuum-pressure. Material and Methods 72 frameworks were cast from CP Ti (n=36) and Co-Cr alloy (n=36; control group). For each material, 18 frameworks were casted by electromagnetic induction and injected by centrifugation, whereas the other 18 were casted by plasma and injected by vacuum-pressure. For each casting method, three subgroups (n=6) were formed: 0.25 mm, 0.50 mm, and 0.75 mm undercuts. The specimens were radiographed and subjected to an insertion/removal test simulating 5 years of framework use. Data were analyzed by ANOVA and Tukey's to compare materials and cast methods (α=0.05). Results Three of 18 specimens of the induction/centrifugation group and 9 of 18 specimens of plasma/vacuum-pressure cast presented porosities, but only 1 and 7 specimens, respectively, were rejected for simulation test. For Co-Cr alloy, no defects were found. Comparing the casting methods, statistically significant differences (p<0.05) were observed only for the Co-Cr alloy with 0.25 mm and 0.50 mm undercuts. Significant differences were found for the 0.25 mm and 0.75 mm undercuts dependent on the material used. For the 0.50 mm undercut, significant differences were found when the materials were induction casted. Conclusion Although both casting methods produced satisfactory CP Ti RPD frameworks, the occurrence of porosities was greater in the plasma/vacuum-pressure than in the induction/centrifugation method, the latter resulting in higher clasp rigidity, generating higher retention force values. PMID:21085805

  5. Evaluation of Superplastic Forming and Weld-brazing for Fabrication of Titanium Compression Panels

    NASA Technical Reports Server (NTRS)

    Royster, D. M.; Bales, T. T.; Davis, R. C.

    1985-01-01

    The two titanium processing procedures, superplastic forming and weld brazing, are successfully combined to fabricate titanium skin stiffened structural panels. Stiffeners with complex shapes are superplastically formed using simple tooling. These stiffeners are formed to the desired configuration and required no additional sizing or shaping following removal from the mold. The weld brazing process by which the stiffeners are attached to the skins utilize spot welds to maintain alignment and no additional tooling is required for brazing. The superplastic formed/weld brazed panels having complex shaped stiffeners develop up to 60 percent higher buckling strengths than panels with conventional shaped stiffeners. The superplastic forming/weld brazing process is successfully scaled up to fabricate full size panels having multiple stiffeners. The superplastic forming/weld brazing process is also successfully refined to show its potential for fabricating multiple stiffener compression panels employing unique stiffener configurations for improved structural efficiency.

  6. Electron beam welding of aircraft structures. [joining of titanium alloy wing structures on F-14 aircraft

    NASA Technical Reports Server (NTRS)

    Witt, R. H.

    1972-01-01

    Requirements for advanced aircraft have led to more extensive use of titanium alloys and the resultant search for joining processes which can produce lightweight, high strength airframe structures efficiently. As a result, electron beam welding has been investigated. The following F-14A components are now being EB welded in production and are mainly annealed Ti-6Al-4V except for the upper wing cover which is annealed Ti-6Al-6V-2Sn: F-14A wing center section box, and F-14A lower and upper wing covers joined to wing pivot fitting assemblies. Criteria for selection of welding processes, the EB welding facility, development work on EB welding titanium alloys, and F-14A production and sliding seal electron beam welding are reported.

  7. The Effect of Nitrogen and Titanium on the Toughness of High Strength Saw Weld Deposits

    DTIC Science & Technology

    1989-05-12

    for joining high strength steels . In this endeavor, ten butt-welded HY-100 sample plates were produced using the submerged arc welding process. With...was shown to degrade toughness. In this case, the DBTT increased at a rate of +11C for every 0.01 weight percent increase in titanium. Examination of...to degrade toughness through precipitation and dispersion hardening effects. It is concluded that for the welding of high strength steels , nitrogen

  8. Wear resistance improvement of a commercially pure titanium by high current pulsed electron beam treatment

    NASA Astrophysics Data System (ADS)

    Zhang, Xiangdong; Wang, Xiaoying; Li, Fangfang; Xiao, Hong

    2017-03-01

    A commercially pure titanium was selected as target material and treated by high current pulsed electron beam. The phase and structure changes occurring in the modified surface layers were observed with optical microscopy, scanning electron microscope, and transmission electron microscope. The increase in the wear resistance was observed for the pure titanium samples after pulsed electron beam surface melting. The mechanism for wear resistance modification was discussed. The results indicated that the presence of ultrafine martensite and defects in the treated surface layer were key factors for the improvement of the wear properties of pure titanium treated by high current pulsed beam treatment.

  9. Double Glow Plasma Surface Alloying Antibacterial Silver Coating on Pure Titanium

    NASA Astrophysics Data System (ADS)

    Lin, Naiming; Guo, Junwen; Hang, Ruiqiang; Zou, Jiaojuan; Tang, Bin

    2014-03-01

    In order to endow the commercial pure titanium dental implant material with antibacterial property and aimed at avoiding the invalidation that is caused by bacterial adhesion on the surface, a silver coating was fabricated via double glow plasma surface alloying. The antibacterial property of the silver coating was assessed via in vitro estimation. The results showed that a continuous and compact coating was formed. The silver coating had absolute superiority in antibacterial property to raw commercial pure titanium. Double glow plasma surface alloying with silver on commercial pure titanium dental implant material could be considered as a potentially effective method for preventing bacterial adhesion.

  10. Double Glow Plasma Surface Alloying Antibacterial Silver Coating on Pure Titanium

    NASA Astrophysics Data System (ADS)

    Lin, Naiming; Guo, Junwen; Hang, Ruiqiang; Zou, Jiaojuan; Tang, Bin

    2014-12-01

    In order to endow the commercial pure titanium dental implant material with antibacterial property and aimed at avoiding the invalidation that is caused by bacterial adhesion on the surface, a silver coating was fabricated via double glow plasma surface alloying. The antibacterial property of the silver coating was assessed via in vitro estimation. The results showed that a continuous and compact coating was formed. The silver coating had absolute superiority in antibacterial property to raw commercial pure titanium. Double glow plasma surface alloying with silver on commercial pure titanium dental implant material could be considered as a potentially effective method for preventing bacterial adhesion.

  11. Electrochemical anodizing treatment to enhance localized corrosion resistance of pure titanium.

    PubMed

    Prando, Davide; Brenna, Andrea; Bolzoni, Fabio M; Diamanti, Maria V; Pedeferri, Mariapia; Ormellese, Marco

    2017-01-26

    Titanium has outstanding corrosion resistance due to the thin protective oxide layer that is formed on its surface. Nevertheless, in harsh and severe environments, pure titanium may suffer localized corrosion. In those conditions, costly titanium alloys containing palladium, nickel and molybdenum are used. This purpose investigated how it is possible to control corrosion, at lower cost, by electrochemical surface treatment on pure titanium, increasing the thickness of the natural oxide layer. Anodic oxidation was performed on titanium by immersion in H2SO4 solution and applying voltages ranging from 10 to 80 V. Different anodic current densities were considered. Potentiodynamic tests in chloride- and fluoride-containing solutions were carried out on anodized titanium to determine the pitting potential. All tested anodizing treatments increased corrosion resistance of pure titanium, but never reached the performance of titanium alloys. The best corrosion behavior was obtained on titanium anodized at voltages lower than 40 V at 20 mA/cm2. Titanium samples anodized at low cell voltage were seen to give high corrosion resistance in chloride- and fluoride-containing solutions. Electrolyte bath and anodic current density have little effect on the corrosion behavior.

  12. Corrosion behavior of pure titanium and titanium alloys in fluoride-containing solutions.

    PubMed

    Nakagawa, M; Matsuya, S; Udoh, K

    2001-12-01

    The effects of fluoride concentrations and pH on the corrosion behavior of pure titanium, Ti-6Al-4V, Ti-6Al-7Nb alloys and a new Ti alloy adding palladium, which is expected to promote a repassivation of Ti were examined by anodic polarization and corrosion potential measurements. The amount of dissolved Ti was analyzed by inductively coupled plasma mass spectroscopy. The surface of the specimen was analyzed by X-ray photoelectron spectroscopy before and after the measurement. Pure Ti, Ti-6Al-4V and Ti-6Al-7Nb alloys were easily corroded even in a low fluoride concentration in an acidic environment. The corrosion resistance of Ti-0.2Pd alloy was greater than those of pure Ti, Ti-6Al-4V and Ti-6Al-7Nb alloys in the wide range of pH and fluoride concentrations. The high corrosion resistance of Ti-0.2Pd alloy was caused by the surface enrichment of Pd promoting a repassivation of Ti. The Ti-0.2Pd alloy is expected to be useful as a new Ti alloy with high corrosion resistance in dental use.

  13. Optimizatin Of Pulsed Nd:YAG Laser Parameters For Titanium Seam-Welding

    NASA Astrophysics Data System (ADS)

    Akman, E.; Canel, T.; Demir, A.; Sinmazcelik, T.

    2007-04-01

    Titanium alloys are the most advantageous metals for the medical and aerospace industry because of their light weight and excellent corrosion resistance. Several techniques were investigated to achieve reliable welds with optimal distortion for the fabrication components used in industry. Laser welding is the most important joining technique because of its precision, rapid processing. For pulse mode Nd:YAG laser; pulse shape, energy, duration, repetition rate and peak power are the most important parameters effects the weld quality. And also the combinations of these parameters are very important for pulsed laser seam-welding. In this study, an experimental work has been done to determine the pulsed laser seam-welding parameters for 3mm thick titanium alloys using the Lumonics JK760TR Nd:YAG pulsed laser.

  14. Effect of minor chemistry elements on GTA weld fusion zone characteristics of a commercial grade titanium

    SciTech Connect

    Marya, S.K.

    1996-06-01

    Gas Tungsten Arc Welding (GTAW) is the most common technique employed in the fabrication of rolled thin tubes. One of the major manufacturing problems concerns the stability of weld fusion zone on materials from different casts, notwithstanding stringent monitoring of the process parameters -- current, voltage and travel speed. These parameters determine the theoretical weld heat and are expected to control the instantaneous mass of melt. According to the data compiled by Sahoo et al., oxygen is known to reduce the surface tension of most of the metals. However, investigations on the role of minor changes in concentrations of elements like sulphur, oxygen, selenium, bismuth, aluminium, and titanium in steels have very often attributed the cast to cast variations to different temperature gradients of surface tension over the weldpool. To the author`s knowledge, no reported work so far has revealed changing weld profiles in autogeneous mechanized GTA welds on titanium due to minor composition changes.

  15. Measurement and material modeling of biaxial work-hardening behavior for pure titanium sheet

    NASA Astrophysics Data System (ADS)

    Sumita, Takeshi; Kuwabara, Toshihiko

    2013-12-01

    Biaxial tensile tests of a commercial pure titanium sheet (JIS ♯1) were performed using a servo-controlled multiaxial tube expansion testing machine developed by one of the authors [Kuwabara, T. and Sugawara, F., Multiaxial tube expansion test method for measurement of sheet metal deformation behavior under biaxial tension for a large strain range, Int. J. Plasticity, 45 (2013), 103-118]. Tubular specimens with an inner diameter of 54 mm were fabricated by roller bending and TIG welding the as-received test material with a thickness of 0.5 mm. Several linear stress paths in the first quadrant of the stress space were applied to the tubular specimens to measure the contours of plastic work and the directions of the plastic strain rates for an equivalent plastic strain range of 0.05 ≤ ɛ0p ≤ 0.30. It was found that the shapes of the work contours significantly changed with an increase in ɛ0p and that the Yld2000-2d yield function could reproduce the differential work hardening behavior of the test material by changing the material parameters and the exponent as functions of ɛ0p.

  16. An evaluation of biocompatibility of indigenously produced pure titanium: an experimental study in rabbits.

    PubMed

    Chittaranjan, Bhogisetty; Murthy, Late Bhamidipati Sreerama; Ravindranath, Turaga

    2012-10-01

    The indigenously produced pure titanium dental implants are economical and useful for common human use in India. The aim of this study is to test the biocompatibility of the indigenously produced pure titanium dental implant material obtained from the Defense Metallurgical Research Laboratory, Hyderabad, India, and the Institute of Nuclear Medicine and Allied Science, Delhi, India. An experimental study in rabbits was done to study the amount of ordered bone formation around the screw and cylinder type of indigenously produced pure titanium metal implant specimens. The experimental animals were killed at 4, 6, 8, 12, and 16 weeks from the date of implantation. The histopathological examination of the animals killed at 16 weeks demonstrates the presence of osteoblastic cell proliferation and early ordered bone formation toward the implant site, indicating signs of osseointegration of both screw- and cylinder-type indigenously produced pure titanium specimens.

  17. Microstructure Refinement After the Addition of Titanium Particles in AZ31 Magnesium Alloy Resistance Spot Welds

    NASA Astrophysics Data System (ADS)

    Xiao, L.; Liu, L.; Esmaeili, S.; Zhou, Y.

    2012-02-01

    Microstructural evolution of AZ31 magnesium alloy welds without and with the addition of titanium powders during resistance spot welding was studied using optical microscopy, scanning electron microscopy, and transmission electron microscopy (TEM). The fusion zone of AZ31 magnesium alloy welds could be divided into columnar dendritic zone (CDZ) and equiaxed dendritic zone (EDZ). The well-developed CDZ in the vicinity of the fusion boundary was clearly restricted and the coarse EDZ in the central region was efficiently refined by adding titanium powders into the molten pool, compared with the as-received alloy welds. A microstructural analysis showed that these titanium particles of approximately 8 µm diameter acted as inoculants and promoted the nucleation of α-Mg grains and the formation of equiaxed dendritic grains during resistance spot welding. Tensile-shear testing was applied to evaluate the effect of titanium addition on the mechanical properties of welds. It was found that both strength and ductility of magnesium alloy welds were increased after the titanium addition. A TEM examination showed the existence of an orientation matching relationship between the added Ti particles and Mg matrix, i.e., [ {0 1bar{1}0} ]_{{Mg}} // [ { 1bar{2} 1bar{3}} ]_{{Ti}} {{and}} ( {000 2} )_{{Mg}} // ( 10bar{1}0)_{{Ti}} in some grains of Ti polycrystal particles. This local crystallographic matching could promote heterogeneous nucleation of the Mg matrix during welding. The diameter of the added Ti inoculant should be larger than 1.8 µm to make it a potent inoculant.

  18. The use of Spark Plasma Sintering method for high-rate diffusion welding of high-strength UFG titanium alloys

    NASA Astrophysics Data System (ADS)

    Nokhrin, A. V.; Chuvil'deev, V. N.; Boldin, M. S.; Piskunov, A. V.; Kozlova, N. A.; Chegurov, M. K.; Popov, A. A.; Lantcev, E. A.; Kopylov, V. I.; Tabachkova, N. Yu

    2017-07-01

    The article provides an example of applying the technology of spark plasma sintering (SPS) to ensure high-rate diffusion welding of high-strength ultra-fine-grained UFG titanium alloys. Weld seams produced from Ti-5Al-2V UFG titanium alloy and obtained through SPS are characterized by high density, hardness and corrosion resistance.

  19. Nucleation and growth of titanium aluminide in an explosion-welded laminate composite

    NASA Astrophysics Data System (ADS)

    Bataev, I. A.; Bataev, A. A.; Mali, V. I.; Pavlyukova, D. V.; Yartsev, P. S.; Golovin, E. D.

    2012-10-01

    Processes of nucleation and growth of titanium aluminide in a 23-layer aluminum-titanium composite produced by explosion welding have been studied. In the vortex zones of seven upper welds, microvolumes of melted metal whose microhardness is ˜5500 MPa have been revealed, which corresponds to the microhardness of the intermetallic compound Al3Ti. No formation of titanium aluminide in welded junctions that were not subjected to additional heat treatment has been revealed by X-ray diffraction. The holding of the composites at 630°C is accompanied by the formation of interlayers of intermetallic compounds of the Al3Ti type. Intermetallic compounds of two morphological types are formed in the welds. In the regions of vortex zones, compact precipitates of Al3Ti are formed; in the other regions of the welds, intermetallic compounds in the form of a film are precipitated. The intermetallic compounds of the first type grow more rapidly and in final account absorb the precipitates of the film type. The activation of diffusion in the upper junctions that occurs upon heating of the welded composites is favored by the nonequilibrium state of the material caused by the strain hardening of the initial samples. In the welds located deeper than the 13th layer, no signs of the formation of compact intermetallic compounds have been revealed upon the annealing for 5 h and less.

  20. Effect of aluminium oxide sandblasting on cast commercially pure titanium surfaces.

    PubMed

    Papadopoulos, T; Tsetsekou, A; Eliades, G

    1999-03-01

    Studies on the titanium porcelain interface have shown the presence of alumina, attributed mainly to the sandblasting procedure. In this study, an investigation of the effect of the sandblasting procedure on the microstructure and roughness of a cast commercially pure titanium surface was undertaken using three different particle size alumina powders. The analysis showed that in all cases alumina particles are embedded into the surface layer of titanium. The use of a large particle size alumina seems to be advantageous in reducing the weight of alumina remaining on the titanium surface and while increasing the surface roughness, thus promoting mechanical interlocking with porcelain.

  1. [The role of fetus decalcified bone matrix (FDBM) in inducing pure titanium-bone implant integration].

    PubMed

    Zou, L; Zhang, D; Wang, W

    1998-05-01

    Because of its high biological compatibility, titanium has been a good biomaterial. The implanted artificial bone made from titanium can contact with the vital and mature osseous tissue directly within 3-6 months, the so-called osteointergration. In order to promote the process of osteointergration, FDBM of rabbit was prepared and was combined with pure titanium so as to speed up osteointergration. The study focused on bone density, bone intergration rate, new bone growth rate around the pure titanium, and the Ca2+ and PO(4)3- density of titanium-bone interface. A control group of pure titanium inplant without FDBM was set up. The results showed FDBM had no antigenicity. It could induce and speed up the new bone formation at titanium-bone interface. The titanium-bone intergration time was within 2 months. It was suggested that there were more bone morphogenesis protein (BMP) or other bone induction and bone formation factors in brephobone than that in child and adult bone. As a kind of bone induction material, FDBM was easy prepared, cheap in price, easy to storage, no antigenicity and obvious bone-inductive function.

  2. Achieving High Strength Joint of Pure Copper Via Laser-Cold Metal Transfer Arc Hybrid Welding

    NASA Astrophysics Data System (ADS)

    Chen, Yulong; Chen, Cong; Gao, Ming; Zeng, Xiaoyan

    2016-06-01

    Fiber laser-cold metal transfer arc hybrid welding of pure copper was studied. Weld porosity was tested by X-ray nondestructive testing. Microstructure and fracture features were observed by scanning electron microscopy. Mechanical properties were evaluated by cross weld tensile test. Full penetrated and continuous welds were obtained by hybrid welding once the laser power reached 2 kW, while they could not be obtained by laser welding alone, even though the laser power reached 5 kW. The ultimate tensile strength (UTS), the yield strength (YS), and the elongation of the best hybrid weld material were up to 227, 201 MPa, and 21.5 pct, respectively. The joint efficiencies in UTS and YS of hybrid weld were up to 84 and 80 pct of the BM, respectively. The fracture location changes from the fusion zone to the heat-affected zone with the increase of laser power. Besides, the mechanisms of process stability and porosity suppression were clarified by laser-arc interaction and pool behavior. The strengthening mechanism was discussed by microstructure characteristics.

  3. Marginal and internal adaptation of commercially pure titanium and titanium-aluminum-vanadium alloy cast restorations.

    PubMed

    Al Wazzan, Khalid A; Al-Nazzawi, Ahmad A

    2007-01-01

    The purpose of this in vitro study was to investigate the marginal accuracy and internal fit of complete cast crowns and three-unit fixed partial dentures (FPDs) cast with commercially pure titanium (CPTi) and Titanium-Aluminum-Vanadium alloy (Ti-6Al-4V). CPTi and Ti-6Al-4V alloy were used to cast twelve single crowns and twelve three-unit FPDs. A traveling microscope was used to measure marginal gap and discrepancies in internal fit. Two and one-way analysis of variance (ANOVA) analyses were used to determine the effects of the marginal and internal fit discrepancies. The Ti-6Al-4V alloy demonstrated a significantly smaller marginal gap than CPTi (P<0.0001). The recorded marginal discrepancies for both metals were within a clinically accepted range (<100 microm). The single crown fit discrepancy was significantly smaller than the three-unit FPD for both the CPTi and the Ti-6Al-4V alloy (P<0.0001). For the internal fit discrepancy, the occlusal surface showed the greatest gaps. The Ti-6Al-4V alloy demonstrated a better fit than CPTi. Single crowns showed an improved fit when compared with the three-unit FPD. Mid-occlusal internal gap demonstrated greater values than the axial internal gap. This in vitro study suggested marginal fit of complete crowns and three-unit FPDs cast by CPTi or Ti-6Al-4V alloy were within the range of what is clinically acceptable for longevity of restorations.

  4. The Effect of Titanium Inclusions on HY-80 GMA Weld Deposits

    DTIC Science & Technology

    1990-12-01

    Titanium Inclusions, HY-80 GMA Weld Deposits. 19 Abstract (continue on reverse if necessary and identiffy by block number) HY-80 steels are used in...submarine and ship construction and it has been found that small additions of titanium to this steel during manufacture markedly improve the fracture...toughness of the heat affected zone (HAZ) of Gas-MetaI-Arc-NWeldin) IGNMAW) deposits made from this steel . This has been ascribed to prior austenite grain

  5. Gravitational effects on the GTA weld pool size of a pure metal

    NASA Astrophysics Data System (ADS)

    Domey, Jeffrey John

    Understanding the physical phenomena involved in the welding process is of substantial value to improving the weldability of materials. The nature of arc welding restricts direct observation during the welding process to surface phenomena, and physical observation of the weld is limited to solidified welds. Thus, accurate computational simulations are needed to provide a better understanding of the transient phenomena that are present during the welding process. One of the major factors affecting the motion within the molten weld pool is the gravity-driven buoyancy force. This force opposes the electromagnetic force induced flow for the straight polarity (direct-current electrode negative) GTA weld. The buoyancy force can also act to oppose or enhance the Marangoni convective flow within the weld pool depending on the sign of the surface tension temperature coefficient. An extensive study involving both numerical as well as physical experiments of the GTA welding process covering a variety of gravitational fields has been performed. Numerical experiments, utilizing the WELDER code, were conducted for stationary GTA welds onto an aluminum alloy. It was found that at a g-level of 0.1g, the convective flow was dominated by the electromagnetic force, while at higher g-levels, 1.0g and 2.0g, the convective flow was dominated by the buoyancy force. It was also found that the depth-to-width (d/w) ratio decreased as the g-level increased for 0.1g to 2.0g. Numerical experiments were also performed in the 1.0g to 10.0g range for stationary GTA welds onto commercially pure nickel. It was found that the electro-magnetic force dominated all of the simulations, although as the g-level increased, the buoyancy force increased causing a decrease in the depth of the fusion zone. This decrease in depth caused a decrease in the d/w ratio of the fusion zone as the g-level increased. Physical experiments for GTA welding of commercially pure nickel in the high-g range (up to 10.0g) were

  6. Revival of pure titanium for dynamically loaded porous implants using additive manufacturing.

    PubMed

    Wauthle, Ruben; Ahmadi, Seyed Mohammad; Amin Yavari, Saber; Mulier, Michiel; Zadpoor, Amir Abbas; Weinans, Harrie; Van Humbeeck, Jan; Kruth, Jean-Pierre; Schrooten, Jan

    2015-09-01

    Additive manufacturing techniques are getting more and more established as reliable methods for producing porous metal implants thanks to the almost full geometrical and mechanical control of the designed porous biomaterial. Today, Ti6Al4V ELI is still the most widely used material for porous implants, and none or little interest goes to pure titanium for use in orthopedic or load-bearing implants. Given the special mechanical behavior of cellular structures and the material properties inherent to the additive manufacturing of metals, the aim of this study is to investigate the properties of selective laser melted pure unalloyed titanium porous structures. Therefore, the static and dynamic compressive properties of pure titanium structures are determined and compared to previously reported results for identical structures made from Ti6Al4V ELI and tantalum. The results show that porous Ti6Al4V ELI still remains the strongest material for statically loaded applications, whereas pure titanium has a mechanical behavior similar to tantalum and is the material of choice for cyclically loaded porous implants. These findings are considered to be important for future implant developments since it announces a potential revival of the use of pure titanium for additively manufactured porous implants.

  7. Effect of silica coating on the bond strength of milled pure titanium to dental porcelain.

    PubMed

    Ye, Jiantao; Ye, Xiuhua; Chang, Shaohai; Liu, Lang; Zhang, Yiping; Lin, Shiyao

    2016-10-01

    The creation of a high bond strength between machined computer-manufactured pure titanium and porcelain remains problematic, and the effects of a silica coating on the bond strength of milled pure titanium bonded to dental porcelain require further investigation. The objective of this study was to evaluate the bond strength of machined pure titanium, with an intermediate coating of silica, to dental porcelain. In this work, 24 specimens of milled pure titanium were prepared and randomly divided into test and control groups, in which the test group was coated with silica using the sol-gel dipping technique. The metal-ceramic bond strength was evaluated, according to ISO 9693 standards, using the three-point bending test, and scanning electron microscopy and energy-dispersive spectroscopy were used to study the microstructure and elemental composition of the specimens. The bonding strength of the silica-coated group was significantly higher than that of the control group, and more residual porcelain on the metal surface could be observed in the silica-coated group. Therefore, the application of a silica intermediate coating produced using the sol-gel method could significantly improve the bond strength between machined pure titanium and porcelain.

  8. Titanium

    USGS Publications Warehouse

    Bedinger, G.M.

    2013-01-01

    Titanium is the ninth most abundant element in the earth’s crust and can be found in nearly all rocks and sediments. It is a lithophile element with a strong affinity for oxygen and is not found as a pure metal in nature. Titanium was first isolated as a pure metal in 1910, but it was not until 1948 that metal was produced commercially using the Kroll process (named after its developer, William Kroll) to reduce titanium tetrachloride with magnesium to produce titanium metal.

  9. Characteristics of multi-layer coating formed on commercially pure titanium for biomedical applications.

    PubMed

    Teker, Dilek; Muhaffel, Faiz; Menekse, Meryem; Karaguler, Nevin Gul; Baydogan, Murat; Cimenoglu, Huseyin

    2015-03-01

    An innovative multi-layer coating comprising a bioactive compound layer (consisting of hydroxyapatite and calcium titanate) with an underlying titanium oxide layer (in the form of anatase and rutile) has been developed on Grade 4 quality commercially pure titanium via a single step micro-arc oxidation process. Deposition of a multi-layer coating on titanium enhanced the bioactivity, while providing antibacterial characteristics as compared its untreated state. Furthermore, introduction of silver (4.6wt.%) into the multi-layer coating during micro-arc oxidation process imposed superior antibacterial efficiency without sacrificing the bioactivity.

  10. Passive fit of frameworks in titanium and palladium-silver alloy submitted the laser welding.

    PubMed

    de Sousa, S A; de Arruda Nobilo, M A; Henriques, G E P; Mesquita, M F

    2008-02-01

    This study evaluated the precision of fit of implant frameworks cast in titanium (cp Ti) and palladium-silver alloy (Pd-Ag), made by the one-piece cast and laser welding techniques. From a metal matrix with five implants, 20 master casts were obtained, to which replicas of implants were incorporated. On these masters 10 frameworks were made for each type of material (cp Ti and Pd-Ag alloy). Half of these were made by the one-piece cast technique and the other half by the laser welding technique. The implant/prosthesis interface was analysed and measured in the vestibular and lingual regions of the central and distal implants with the help of a measuring microscope. The results indicated that in the central cylinders, the Tukey test (P<0.0005) showed a significant difference in the passive fit between the laser-welded frameworks (34.73 microm) and those one-piece cast frameworks (151.39 microm), and as regards materials, the palladium-silver alloy (66.30 microm) showed better results than the titanium (119.83 microm). In the distal cylinders there was no significant difference between the frameworks cast in titanium and palladium-silver by the one-piece technique. However, after laser welding, there was a significant difference for the frameworks cast in titanium (31.37 microm) and palladium-silver (106.59 microm).

  11. Effects of interfacial variables on ceramic adherence to cast and machined commercially pure titanium.

    PubMed

    Sadeq, Abdulaziz; Cai, Zhuo; Woody, Ronald D; Miller, Amp W

    2003-07-01

    Titanium-ceramic bonding is less optimal than conventional metal-ceramic bonding, due to excessive oxidation of titanium during porcelain firing. This in vitro study evaluated the effects of porcelain firing atmosphere and gold sputter coating on titanium surfaces on porcelain bonding to machined and as-cast titanium substrates. Material and methods Eight groups of ASTM grade 2 commercially pure (CP) titanium specimens (13 mm x13 mm x1 mm) were prepared (n=10). A conventional Au-Pd-In metal-ceramic alloy (Orion) and an ultra low-fusing porcelain (Finesse) served as the control (n=10). Forty machined titanium specimens were prepared from 1.00-mm thick titanium sheets with a diamond band saw. Forty titanium specimens were produced in a centrifugal dental titanium casting machine. All titanium specimens were airborne particle abraded with 110-microm alumina particles, whereas the control specimens were airborne particle abraded with 50-microm alumina particles. Forty titanium specimens (20 specimens each of as-cast and machined titanium) were randomly selected for gold sputter coating before ceramic firing. An ultra low-fusing porcelain (Vita Titankeramik) was fused on the central 6-mm diameter circular area on each titanium specimen. Porcelain firing environments for the titanium specimens consisted of vacuum and a reduced argon atmosphere. Porcelain was debonded by a biaxial flexure, constant strain test at a cross-head speed of 0.25 mm/min. Specimens were analyzed by standardized SEM/EDS analysis 3 times throughout the study to determine the silicon atomic percentage (Si at %): (1) after airborne particle abrasion, before porcelain application; (2) after the application of the first layer of porcelain; and (3) after the fracture of porcelain from the metal substrate. The titanium-ceramic adhesion was characterized by determining the area fraction of adherent porcelain (AFAP). Results were analyzed by analysis of variance and the Student-Newman-Keuls test (alpha=.05

  12. Ultrasonic Spot and Torsion Welding of Aluminum to Titanium Alloys: Process, Properties and Interfacial Microstructure

    NASA Astrophysics Data System (ADS)

    Balle, Frank; Magin, Jens

    Hybrid lightweight structures shape the development of future vehicles in traffic engineering and the aerospace industry. For multi-material concepts made out of aluminum and titanium alloys, the ultrasonic welding technique is an alternative effective joining technology. The overlapped structures can be welded in the solid state, even without gas shielding. In this paper the conventional ultrasonic spot welding with longitudinal oscillation mode is compared to the recent ultrasonic torsion welding with a torsional mode at 20 kHz working frequency. For each technique the process parameters welding force, welding energy and oscillation amplitude were optimized for the hybrid joints using design of experiments. Relationships between the process parameters, mechanical properties and related welding zone should be understood. Central aspects of the research project are microscopic studies of the joining zone in cross section and extensive fracture surface analysis. Detailed electron microscopy and spectroscopy of the hybrid interface help to understand the interfacial formation during ultrasonic welding as well as to transfer the gained knowledge for further multi-metal joints.

  13. [Effects on microstructure and mechanical property of pure titanium (TA1) treated by anodic oxidation].

    PubMed

    Pan, Liuguo; Sun, Liqun

    2008-12-01

    Effects on surface microstructure and mechanical property of pure titanium (TA1) for implant treated by anodic oxidation were investigated. We found that the oxide film with a certain uniform and compact color could be achieved by anodic oxidation method. However, with the increasing of oxidizing voltage and time, the oxide film will be dissolved at local area. The oxygen content of oxide film and the hydrogen content of matrix titanium will be raised, and will also be increased. In fact, hydrogen could be diffused into matrix titanium. With the increase of hydrogen content of matrix titanium and sigmas/sigmab, there appear the possible results of plastic deformation and the fracture of implant.

  14. New mechanism for the alpha to omega martensitic transformation in pure titanium.

    PubMed

    Trinkle, D R; Hennig, R G; Srinivasan, S G; Hatch, D M; Jones, M D; Stokes, H T; Albers, R C; Wilkins, J W

    2003-07-11

    We propose a new direct mechanism for the pressure driven alpha-->omega martensitic transformation in pure titanium. A systematic algorithm enumerates all possible pathways whose energy barriers are evaluated. A new, homogeneous pathway emerges with a barrier at least 4 times lower than other pathways. The pathway is shown to be favorable in any nucleation model.

  15. Susceptibility of Welded and Non-Welded Titanium Alloys to Environmentally Assisted Cracking in Simulated Concentrated Ground Waters

    SciTech Connect

    Fix, D V; Estill, J C; Wong, L L; Rebak, R B

    2003-10-14

    The engineering barriers for the nuclear waste repository at Yucca Mountain include a double walled container and a detached drip shield. The material selected to construct the drip shield will be Titanium Grade 7 (Ti Gr 7 or R52400). Ti Gr 7 is highly resistant to corrosion and consequently it is widely used to handle aggressive industrial environments. The model for the degradation of the engineering barriers includes three modes of corrosion, namely general corrosion, localized corrosion and environmentally assisted cracking (EAC). The objective of the current research was to characterize the susceptibility of three titanium alloys to EAC in several environmental conditions with varying solution composition, pH and temperature. The susceptibility to EAC was evaluated using constant deformation (deflection) U-bend specimens in both the non-welded and welded conditions. Results show that after more than five years exposure in the vapor and liquid phases of alkaline (pH {approx} 10) and acidic (pH {approx} 3) multi-ionic environments at 60 C and 90 C, most of the specimens were free from EAC. The only specimens that suffered EAC were welded Ti Gr 12 (R53400) exposed to liquid simulated concentrated water (SCW) at 90 C.

  16. Joining characteristics of beta-titanium wires with electrical resistance welding.

    PubMed

    Iijima, Masahiro; Brantley, William A; Yuasa, Toshihiro; Kawashima, Isao; Mizoguchi, Itaru

    2008-05-01

    The goal of this research was to investigate the effects of different conditions for electrical resistance welding of beta-titanium orthodontic wires. Three electrode types were used with a range of power settings on an electrical resistance welding machine to join beta-titanium wires (Resolve, GAC International). Forces that caused bond failures for joined specimens were obtained with tensile loading, and the values were compared using one-way ANOVA and the Tukey test (alpha = 0.05). Metallurgical phases in the joint region were determined by micro-X-ray diffraction. Mean tensile forces for bond failure ranged from 5 to 20 kgf for the eight specimen groups and were dependent on electrode type and power setting. All X-ray diffraction peaks in the joint region were indexed to beta-titanium. Superior bond strength was achieved with the use of wide electrodes. The absence of phases other than beta-titanium in the joint area suggests that the electrical resistance welding may not adversely affect clinically important mechanical properties. Scanning microscope observations indicated that the localized permanent deformation and the formation of an undesirable equiaxed grain structure occurred with the use of narrow electrodes.

  17. The relationship between the super plasticity of laser welding joint of titanium alloy and hydrogen treatment

    NASA Astrophysics Data System (ADS)

    Cao, Zean; Cheng, Donghai; Jiang, Xunyan; Hu, Dean; Chen, Yiping

    2017-06-01

    The superplastic deformation uniformity of laser welded joint of TC4 titanium alloy is improved by hydrogen treatment. The non-uniform deformation coefficient K was introduced to quantification ally characterize the non-uniform deformation. The results show when the content of hydrogen exceeds 0.29%, the super plasticity of the titanium alloy welded plate decreases with the increase of the hydrogen content. The decrease of the shrinkage of the base material is larger than that of the weld section with the increase of hydrogen content. The K can be used to describe the non-uniform deformation of the weld and the base material during the superplastic deformation of laser welded joint of the TC4. The K value increases with increaseing hydrogen content, increaseing deformation temperature and decreaseing strain rate. The K value reaches the maximum of 0.84 with hydrogen content of 1.299%, deformation temperature of 920 °C, strain rate of 10-4S-1.

  18. Investigation of the vapour-plasma plume in the welding of titanium by high-power ytterbium fibre laser radiation

    NASA Astrophysics Data System (ADS)

    Bykovskiy, D. P.; Petrovskii, V. N.; Uspenskiy, S. A.

    2015-03-01

    The vapour-plasma plume produced in the welding of 6-mm thick VT-23 titanium alloy plates by ytterbium fibre laser radiation of up to 10 kW power is studied in the protective Ar gas medium. High-speed video filming of the vapour-plasma plume is used to visualise the processes occurring during laser welding. The coefficient of inverse bremsstrahlung by the welding plasma plume is calculated from the data of the spectrometric study.

  19. Low-Temperature Nitriding of Pure Titanium by using Hollow Cathode RF-DC Plasma

    NASA Astrophysics Data System (ADS)

    Windajanti, J. M.; S, D. J. Djoko H.; Abdurrouf

    2017-05-01

    Pure titanium is widely used for the structures and mechanical parts due to its high strength, low density, and high corrosion resistance. Unfortunately, titanium products suffer from low hardness and low wear resistance. Titanium’s surface can be modified by nitriding process to overcome such problems, which is commonly conducted at high temperature. Here, we report the low-temperature plasma nitriding process, where pure titanium was utilized by high-density RF-DC plasma combined with hollow cathode device. To this end, a pure titanium plate was set inside a hollow tube placed on the cathode plate. After heating to 450 °C, a pre-sputtering process was conducted for 1 hour to remove the oxide layer and activate the surface for nitriding. Plasma nitriding using N2/H2 gasses was performed in 4 and 8 hours with the RF voltage of 250 V, DC bias of -500 to -600 V, and gas pressure of 75 to 30 Pa. To study the nitriding mechanism as well as the role of hollow cathode, the nitrided specimen was characterized by SEM, EDX, XRD, and micro-hardness equipment. The TiN compound was obtained with the diffusion zone of nitrogen until 5 μm thickness for 4 hours nitriding process, and 8 μm for 8 hours process. The average hardness also increased from 300 HV in the untreated specimen to 624 HV and 792 HV for 4 and 8 hours nitriding, respectively.

  20. Effect of heat treatment in atmosphere on mechanical properties of pure titanium at liquid helium temperature

    SciTech Connect

    Konosu, S.; Nakaniwa, T.; Ivano, O.

    1998-05-12

    Due to their extreme friability, nuclear fusion superconductivity coil materials (NbTi, Nb{sub 3}Sn, Nb{sub 3}Al) are placed in pure titanium rectangular parallelepiped sleeves called conduits, of about 1 mm in wall thickness, and subjected to sintering heat treatment (50 to 200 hours at 923 to 1,023K) to produce superconductive materials. In use, the superconductive coil is immersed in liquid helium (4.2K) and as immense currents flow through the coil, the conduit is subjected to very large electromagnetic forces. As pure titanium is a highly active material, oxided scale forms on the surface when it is heated to high temperatures under atmospheric conditions, together with the formation, beneath the oxided scale, of an oxygen-rich layer possessing intense oxygen solubility. While oxided scale, because of its ability to reduce hydrogen absorption, is being actively used as a means to prevent the hydrogen embrittlement of titanium, it is believed that this leads to a deterioration of the mechanical properties because the oxygen-rich layer is deficient in ductility. The current research is intended to clarify the effect on the tensile test properties at liquid helium temperature (4.2K) of pure titanium and the oxygen-rich layer which forms thereon as a result of the heat treatment under atmospheric conditions.

  1. Influence of Duplex Treatment on Structural and Tribological Properties of Commercially Pure Titanium

    NASA Astrophysics Data System (ADS)

    Çelik, Ilhan

    2017-01-01

    Titanium and its alloys are widely used in many fields, including aerospace and the chemical and biomedical industries. This is due to their mechanical properties, excellent corrosion resistance, and biocompatibility although they do have poor wear resistance. In this study, a duplex layer was successfully formed on the commercially pure titanium surface by duplex treatments (plasma nitriding and physical vapor deposition (PVD)). In the initial treatment, plasma nitriding was performed on the pure titanium samples and in the second treatment, the nitrided samples were coated with CrN by PVD. The friction and wear properties of the duplex-treated samples were investigated for tribological applications. Surface morphology and microstructure of the duplex-treated samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). In addition, the tribological properties were investigated using pin-on-disc tribometer. A compound layer composed of ɛ-Ti2N and δ-TiN phases and a diffusion layer formed under the compound layer were obtained on the surface of pure titanium after the nitriding treatments. CrN coated on the nitrided surface provided an increase in the surface hardness and in the wear resistance.

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

    NASA Astrophysics Data System (ADS)

    Moćko, Wojciech; Kruszka, Leopold; Brodecki, Adam

    2015-09-01

    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. Biocompatibility of pure titanium modified by human endothelial cell-derived extracellular matrix

    NASA Astrophysics Data System (ADS)

    Xue, Xiaoqing; Wang, Jin; Zhu, Ying; Tu, Qiufen; Huang, Nan

    2010-04-01

    Extracellular matrix (ECM) used to modify biomaterial surface is a promising method for improving cardiovascular material hemocompatibility. In the present work, human umbilical vein endothelial cells (HUVECs) are cultured and native ECM is obtained on pure titanium surface. Fourier infrared spectrum (FTIR) test proves the existence of amide I and amide II band on the modified titanium surface. X-ray photoelectron spectroscopy (XPS) further confirms the chemical composition and binding types of the ECM proteins on the titanium substrate. The results of light microscopy and atomic force microscopy (AFM) exhibit the morphology of HUVEC derived ECM. There are higher water contact angles on the ECM modified samples. Furthermore, some ECM components, including fibronectin (FN), laminin (LN) and type IV collagen (IV-COL) are presented on ECM-covered titanium surface by immunofluorescence staining. The biological behavior of cultured HUVECs and adherent platelets on different samples are investigated by in vitro HUVECs culture and platelet adhesion. Cells exhibit better morphology and their proliferation ability greatly improve on the ECM-covered titanium. At the same time, the platelet adhesion and spreading are inhibited on ECM-covered titanium surface. These investigations demonstrate that ECM produced by HUVECs cannot only improve adhesion and proliferation ability of endothelial cell but also inhibit adhesion and activation of platelets. Thus, the approach described here may provide a basis for preparation of modified surface in cardiovascular implants application.

  4. Superplastic forming/weld-brazing of titanium skin-stiffened compression panels

    NASA Technical Reports Server (NTRS)

    Royster, D. M.; Bales, T. T.; Wiant, H. R.

    1982-01-01

    A study was conducted to exploit the processing advantages of superplastic forming and weld-brazing for the fabrication of titanium skin-stiffened structural components. Small titanium compression panels were fabricated and tested at room temperature. Stiffeners having configurations of a conventional hat shape, beaded shaped web, ribbed shaped web, or stepped shaped web were investigated. The data from the panel tests included load-shortening curves, local buckling strengths, and failure loads. Experimental buckling loads were compared with buckling loads calculated using a finite-element analysis. The superplastic formed/weld-brazed panels having complex shaped stiffeners developed from 20 to 58 percent higher local buckling strengths than panels with conventionally shaped stiffeners.

  5. Microstructural Evolution During Friction Stir Welding of Near-Alpha Titanium

    DTIC Science & Technology

    2009-02-01

    material, was initially developed for use on aluminum alloys because of the lower temperatures and stresses required to weld those alloys and the ready...focused on aluminum alloys. However, there is also substantial interest in developing FSW for higher strength alloys such as titanium and steels. Such...higher loads needed for some of these alloys. Although FSW of these high strength alloys has seen much less development than FSW of aluminum alloys

  6. Fundamental study about CO2 laser welding of titanium aluminide intermetallic compound

    NASA Astrophysics Data System (ADS)

    Kuwahara, Gaku; Yamaguchi, Shigeru; Nanri, Kenzo; Ootani, Masanori; Tetsuka, Masato; Seto, Sachio; Arai, Mikiya; Fujioka, Tomoo

    2000-11-01

    Titanium aluminide intermetallic compound is attracting attentions as heat-resistant and high-specific strength material in the next generation, especially, it is promising material in the field of aerospace components. Conventional machining process including welding, however, can be hardly applied due to its very low ductility. The objective of this study, as a first stage, is to find out paying attention to crack and hardness the fundamental good conditions of the bead-on-plate welding of TiAl intermetallic compound using CO2 laser irradiation. In the experiment, we used the casting gamma titanium aluminide contained iron, vanadium and boron with a thickness of 2mm. We carried out bead-on-plate laser welding in the titanium aluminide material in inert gas environment filled with argon. We measured fused depth, Vickers hardness, transverse crack numbers and so on as major parameters of welding speed from 1000 to 4600 mm/min and initial temperature of specimen from R.T. to 873 K with a beam spot size of 0.5 mm and an output power of 1.5 kW. In addition, the specimens were analyzed by Electron Probe X-ray Micro Analyzer, Energy Dispersive X-ray Spectroscopy and X-ray Diffractometry. As a result of experiments, transverse crack-free welding was achieved, when initial temperature was at 873 K. In every condition, the value of Vickers hardness of fused zone increased compared with base. We think the reason of it is an increase of (alpha) 2(Ti3Al) phase, which is caused by rapid cooling, taking in Oxygen, fine structure and so on.

  7. Welded Titanium Case for Space-Probe Rocket Motor

    NASA Technical Reports Server (NTRS)

    Brothers, A. J.; Boundy, R. A.; Martens, H. E.; Jaffe, L. D.

    1959-01-01

    The high strength-to-weight ratio of titanium alloys suggests their use for solid-propellant rocket-motor cases for high-performance orbiting or space-probe vehicles. The paper describes the fabrication of a 6-in.-diam., 0.025-in.-wall rocket-motor from the 6A1-4V titanium alloy. The rocket-motor case, used in the fourth stage of a successful JPL-NASA lunar-probe flight, was constructed using a design previously proven satisfactory for Type 410 stainless steel. The nature and scope of the problems peculiar to the use of the titanium alloy, which effected an average weight saving of 34%, are described.

  8. Simulation of Local Material Properties during Laser Beam Welding of Aluminum-Titanium Compounds

    NASA Astrophysics Data System (ADS)

    Barr, Annika; Hunkel, Martin; von Hehl, Axel

    Combinations of aluminum and titanium by firmly bonding via laser beam welding enable the production of customized hybrid designs with enhanced properties. A novel approach of coupling process, microstructure and mechanical simulation, considering the development of weld geometry and local material conditions, is intended to deliver a fast and reliable method for evaluating the quasi-static strength of laser beam welded hybrid compounds. For microstructure and mechanical simulations a comprehensive data set of material specific mechanical properties is required to reach simulation results. This includes hot tensile tests, tensile tests concerning the heat affected zone (by means of micro flat specimens) and metallographic examinations to determine the microstructure and hardness. The data set was implemented into a simulation model in order to validate the simulation results including microstructure evolution and resulting local mechanical properties. These results provide the basis for refining and advancing the coupled simulation model.

  9. Influence of titanium and nitrogen on the fracture properties of weld metals

    SciTech Connect

    Kocak, M.; Petrovski, B.I.; Richter, E.; Evans, G.M.

    1994-12-31

    A The effects of titanium and nitrogen contents on the C-Mn shielded metal arc weld (SMAW) metal properties have been studied. There are still uncertainties concerning the exact role of each element and interactions between these elements with respect to the weld metal microstructure and fracture toughness properties. Therefore, systematic additions of titanium (in the range of 5 to 450 ppm) and nitrogen (80, 160 and 240 ppm) were made to obtain various amounts of acicular ferrite and different microstructures which lead to varying fracture behaviors. The research program covers the determination of tensile properties, Charpy-V notch transition curves and crack tip opening displacement (CTOD) fracture toughness values of different weld deposits containing three different nitrogen contents. The results show that an optimum level of titanium (30 ppm) addition enhanced the formation of acicular ferrite and hence improved the Charpy-V impact and CTOD toughness values. An increase of nitrogen increased the strength but caused a drastic deterioration of both Charpy-V impact and CTOD toughness values at the upper shelf and transition regime.

  10. Partially degradable friction-welded pure iron-stainless steel 316L bone pin.

    PubMed

    Nasution, A K; Murni, N S; Sing, N B; Idris, M H; Hermawan, H

    2015-01-01

    This article describes the development of a partially degradable metal bone pin, proposed to minimize the occurrence of bone refracture by avoiding the creation of holes in the bone after pin removal procedure. The pin was made by friction welding and composed of two parts: the degradable part that remains in the bone and the nondegradable part that will be removed as usual. Rods of stainless steel 316L (nondegradable) and pure iron (degradable) were friction welded at the optimum parameters: forging pressure = 33.2 kPa, friction time = 25 s, burn-off length = 15 mm, and heat input = 4.58 J/s. The optimum tensile strength and elongation was registered at 666 MPa and 13%, respectively. A spiral defect formation was identified as the cause for the ductile fracture of the weld joint. A 40-µm wide intermetallic zone was identified along the fusion line having a distinct composition of Cr, Ni, and Mo. The corrosion rate of the pin gradually decreased from the undeformed zone of pure iron to the undeformed zone of stainless steel 316L. All metallurgical zones of the pin showed no toxic effect toward normal human osteoblast cells, confirming the ppb level of released Cr and Ni detected in the cell media were tolerable.

  11. Welding of a corrosion-resistant composite material based on VT14 titanium alloy obtained using an electron beam emitted into the atmosphere

    NASA Astrophysics Data System (ADS)

    Golkovski, M. G.; Samoylenko, V. V.; Polyakov, I. A.; Lenivtseva, O. G.; Chakin, I. K.; Komarov, P. N.; Ruktuev, A. A.

    2017-01-01

    The study investigates the possibility of inert gas arc welding of a double layer composite material on a titanium base with an anti-corrosive layer obtained by fused deposition of a powder mix containing tantalum and niobium over a titanium base using an electron beam emitted into the atmosphere. Butt welding and fillet welding options were tested with two types of edge preparation. Welds were subjected to a metallographic examination including a structural study and an analysis of the chemical and phase composition of the welds. A conclusion was made regarding the possibility of using welding for manufacturing of items from the investigated composite material.

  12. Crestal remodelling and osseointegration at surface-modified commercially pure titanium and titanium alloy implants in a canine model.

    PubMed

    Lee, Jaebum; Hurson, Steve; Tadros, Hatem; Schüpbach, Peter; Susin, Cristiano; Wikesjö, Ulf M E

    2012-08-01

    Ti-6Al-7Nb alloys exhibit enhanced mechanical properties and corrosion resistance and may represent an improvement to present commercially pure (CP) titanium oral implant technology. To evaluate crestal remodelling and osseointegration at CP titanium compared with Ti-6Al-7Nb alloy oral implants using a canine model. Two threaded anodized CP titanium and two Ti-6Al-7Nb alloy anodized oral implants (ø4.5 × 6.1 mm) were placed into each jaw quadrant in the edentulated posterior mandible in six adult male Hound Labrador mongrel dogs. Abutments were placed onto the implants, and the mucogingival flaps were adapted and sutured for transmucosal wound healing. Block biopsies were collected for histometric analysis following an 8-week healing interval. Healing was uneventful. Bone density outside and within the root of the threads averaged (± SE) 49.0 ± 4.5% and 38.7 ± 5.1% for CP titanium implants and 43.2 ± 3.6% and 34.2 ± 4.8% for Ti-6Al-7Nb alloy implants. Mean osseointegration reached 68.0 ± 4.4% and 62.8 ± 2.5% for CP titanium and Ti-6Al-7Nb alloy implants, respectively. Although crestal resorption at lingual sites averaged 0.2 ± 0.1 mm for both technologies, crestal resorption at buccal sites averaged 0.9 ± 0.2 and 1.0 ± 0.6 mm for CP titanium and Ti-6Al-7Nb alloy implants, respectively. There were no statistically significant differences between implant technologies for any parameter assessed. Notably, advanced/advancing buccal crestal resorption exposing the implant threads was observed in 50% of the implants (four of six animals) regardless of implant technology; osteoclastic resorption still observed at 8 weeks following implant placement. Within the limitations of study, anodized Ti-6Al-7Nb alloy implants may represent a feasible alternative to benchmark anodized CP titanium implants. Remodelling of the buccal crestal plate resulting in advanced bone loss appears a major impediment to oral implant osseointegration and possibly, in extension, implant

  13. Estimation of Dislocation Density in Cold-Rolled Commercially Pure Titanium by Using Synchrotron Diffraction

    NASA Astrophysics Data System (ADS)

    ALkhazraji, Hasan; Salih, Mohammed Z.; Zhong, Zhengye; Mhaede, Mansour; Brokmeier, Hans-Günter; Wagner, Lothar; Schell, N.

    2014-08-01

    Cold rolling (CR) leads to a heavy changes in the crystallographic texture and microstructure, especially crystal defects, such as dislocations, and stacking faults increase. The microstructure evolution in commercially pure titanium (cp-Ti) deformed by CR at the room temperature was determined by using the synchrotron peak profile analysis of full width at half maximum (FWHM). The computer program ANIZC has been used for the calculation of diffraction contrast factors of dislocations in elastically anisotropic hexagonal crystals. The dislocation density has a minimum value at 40 pct reduction. The increase of the dislocation density at higher deformation levels is caused by the nucleation of new generation of dislocations from the crystallite grain boundaries. The high-cycle fatigue strength (HCF) has a maximum value at 80 pct reduction and it has a minimum value at 40 pct reduction in the commercially pure titanium.

  14. [The change of bacterial adhesion during deposition nitrogen-diamond like carbon coating on pure titanium].

    PubMed

    Yin, Lu; Xiao, Yun

    2011-10-01

    The aim of this study was to observe the change of bacterial adhesion on pure titanium coated with nitrogen-diamond like carbon (N-DLC) films and to guide the clinical application. N-DLC was deposited on titanium using ion plating machine, TiN film, anodic oxide film and non-deposition were used as control, then made specimens adhering on the surface of resin denture base for 6 months. The adhesion of Saccharomyces albicans on the titanium surface was observed using scanning electron microscope, and the roughness was tested by roughness detector. The number of Saccharomyces albicans adhering on diamond-like carbon film was significantly less than on the other groups (P < 0.05), and the growth of bacterial cell was inhibited and in a poor state. The largest number of adhesion and cell strains grew well on anodic oxide film group and non-deposition control group. The change of surface roughness of N-DLC film was less than other group (P < 0.05). Pure titanium coated with N-DLC film reduced the adhesion of Saccharomyces albicans after clinical application, thereby reduced the risk of denture stomatitis.

  15. Laser surface alloying of commercially pure titanium with boron and carbon

    NASA Astrophysics Data System (ADS)

    Makuch, N.; Kulka, M.; Dziarski, P.; Przestacki, D.

    2014-06-01

    Laser surface alloying with boron and carbon was applied to produce the composite layers, reinforced by the hard ceramic phases (titanium borides and titanium carbides), on commercially pure titanium. The external cylindrical surface of substrate material was coated by paste containing boron, boron and graphite, or graphite. Then, the laser re-melting was carried out with using the continuous-wave CO2 laser. This enabled the formation of laser-borided, laser-borocarburized, and laser-carburized layers. The microstructure or the re-melted zone consisted of the hard ceramic phases (TiB+TiB2, TiB+TiB2+TiC, or TiC) located in the eutectic mixture of Tiα'-phase with borides, borides and carbides, or carbides, respectively. All the composite layers were characterized by the sufficient cohesion. The significant increase in microhardness and in wear resistance of all the laser-alloyed layers was observed in comparison with commercially pure titanium. The percentage of hard ceramic phases in more plastic eutectic mixture influenced the measured microhardness values. The dominant wear mechanism (abrasive or adhesive) depended on the method of laser alloying, and the type of test used. The wear tests for longer duration, without the change in the counter specimen, created the favourable conditions for adhesive wear, while during the shorter tests the abrasive wear dominated, as a rule.

  16. The deformation behavior of commercially pure titanium subjected to electron beam treatment

    SciTech Connect

    Kazachenok, Marina Kozelskaya, Anna; Panin, Alexey; Ivanov, Yurii

    2015-10-27

    The effect of low-energy high-current pulsed electron beam treatment on the microstructure and mechanical properties of commercially pure titanium specimens is studied. Plastic deformation mechanisms of the specimens subjected to the electron beam treatment followed by uniaxial tension are demonstrated. The role of the interface between the hardened surface layer and the relatively soft parent metal in the slip band formation in the loaded specimens is revealed.

  17. Spectral diagnostics of a vapor-plasma plume produced during welding titanium with a high-power ytterbium fiber laser

    NASA Astrophysics Data System (ADS)

    Uspenskiy, S. A.; Petrovskiy, V. N.; Bykovskiy, D. P.; Mironov, V. D.; Prokopova, N. M.; Tret'yakov, E. V.

    2015-03-01

    This work is devoted to the research of welding plume during high power ytterbium fiber laser welding of a titanium alloy in the Ar shielding gas environment. High speed video observation of a vapor-plasma plume for visualization of processes occurring at laser welding was carried out. The coefficient of the inverse Bremsstrahlung absorption of laser radiation is calculated for a plasma welding plume by results of spectrometer researches. The conclusion deals with the impact of plasma on a high-power fiber laser radiation.

  18. Effect of initial orientation on the tensile properties of commercially pure titanium

    NASA Astrophysics Data System (ADS)

    Sinha, Subhasis; Ghosh, Atasi; Gurao, N. P.

    2016-05-01

    Effect of crystallographic texture on uniaxial tensile deformation of commercially pure titanium was studied using in situ as well as post-mortem electron backscatter diffraction and elastoplastic self-consistent simulations. Correlation of mechanical properties and strain hardening response with deformation micromechanisms like different modes of slip and twinning was established. Tensile specimens were machined along rolling direction in the plane perpendicular to normal and transverse direction (sample A and C, respectively) as well as along transverse direction in the plane normal to rolling direction (sample B) to obtain different initial texture from cold rolled and annealed plate of commercially pure titanium. Sample B showed higher strength but lower strain hardening rate and ductility than the orientations A and C. It showed extension twinning with lateral thickening while the other samples showed coexistence of extension and contraction twinning. Schmid factor accounted for most of the observed twinning although some contraction twinning in sample A is attributed to the effect of internal stresses. A combination of in situ tensile test in a field emission gun scanning electron microscope with electron backscatter diffraction facility and elastoplastic self-consistent simulations aid in obtaining high-fidelity Voce hardening parameters for different slip and twinning systems in commercially pure titanium. The variation in tensile properties can be explained on the basis of propensity of twinning which tends to provide strain hardening at lower strain but contributes to failure at higher strain.

  19. Preparation of Copper and Chromium Alloyed Layers on Pure Titanium by Plasma Surface Alloying Technology

    NASA Astrophysics Data System (ADS)

    He, Xiaojing; Li, Meng; Wang, Huizhen; Zhang, Xiangyu; Tang, Bin

    2015-05-01

    Cu-Cr alloyed layers with different Cu and Cr contents on pure titanium were obtained by means of plasma surface alloying technology. The microstructure, chemical composition and phase composition of Cu-Cr alloyed layers were analyzed by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD), respectively. The experimental results demonstrate that the alloyed layers are bonded strongly to pure titanium substrate and consist of unbound Ti, CuTi, Cu3Ti, CuTi3 and Cr2Ti. The thickness of Cu5Cr5 and Cu7Cr3 alloyed layer are about 18 μm and 28 μm, respectively. The antibacterial properties against gram-negative Escherichia coli (E.coli, ATCC10536) and gram-positive Staphylococcus aureus (S. aureus, ATCC6538) of untreated pure titanium and Cu-Cr alloyed specimen were investigated by live/dead fluorescence staining method. The study shows that Cu-Cr alloyed layers exhibit excellent antibacterial activities against both E.coli and S.aureus within 24 h, which may be attributed to the formation of Cu-containing phases.

  20. Microstructure, Growth Kinetics and Some Mechanical Properties of Boride Layers Produced on Pure Titanium by Molten-Salt Boriding

    NASA Astrophysics Data System (ADS)

    Ma, L. S.; Duan, Y. H.; Li, P.

    2017-08-01

    To modify the surface properties of pure titanium, boride layers had been fabricated by the boron molten-salt diffusion on pure titanium surfaces in the temperature range of 900-1100 °C for 5- to 30-h treatments. The results demonstrated that the boride layers were mainly composed of TiB whiskers and TiB2 layers without the rutile titanium oxide TiO2. Two diffusion models were introduced to model the growth kinetics of boride layers. The parabolic growth constants and the boron diffusion coefficients were obtained. The boron activation energies for TiB2 and TiB were 225.617 and 165.266 kJ mol-1, respectively. The surface microhardness of the borided titanium decreased with the increase in distance from the surface. The results of wear tests indicated that the wear properties had been improved significantly compared to the pure titanium under dry sliding conditions.

  1. Explosive Welding of Aluminum, Titanium and Zirconium to Copper Sheet Metal

    NASA Technical Reports Server (NTRS)

    Hegazy, A. A.; Mote, J. D.

    1985-01-01

    The main material properties affecting the explosive weldability of a certain metal combination are the yield strength, the ductility, the density and the sonic velocity of the two metals. Successful welding of the metal combination depends mainly on the correct choice of the explosive welding parameters; i.e., the stand off distance, the weight of the explosive charge relative to the weight of the flyer plate and the detonation velocity of the explosive. Based on the measured and the handbook values of the properties of interest, the explosive welding parameters were calculated and the arrangements for the explosive welding of the Al alloy 6061-T6, titanium and zirconium to OFHC copper were determined. The relatively small sheet metal thickness (1/8") and the fact that the thickness of the explosive layer must exceed a certain minimum value were considered during the determination of the explosive welding conditions. The results of the metallographic investigations and the measurements of the shear strength at the interface demonstrate the usefulness of these calculations to minimize the number of experimental trials.

  2. Welded Titanium Case for Space-Probe Rocket Motor

    NASA Technical Reports Server (NTRS)

    Brothers, A. J.; Boundy, R. A.; Martens, H. E.; Jaffe, L. D.

    1959-01-01

    Early in 1958, the Jet Propulsion Laboratory of the California Institute of Technology was requested to participate in a lunar-probe mission code-named Juno II which would place a 15-lb Instrumented payload (Pioneer IV) in the vicinity of the moon. The vehicle was to use the same high-speed upper-stage assembly as flown on the successful Jupiter-C configuration; however, the first-stage booster was to be a Jupiter rather than a Redstone. An analysis of the intended flight and payload configuration Indicated that the feasibility of accomplishing the mission was questionable and that additional performance would have to be obtained if the mission was to be feasible. Since the most efficient way of Increasing the performance of a staged vehicle is to increase the performance of the last stage, a study of possible ways of doing this was made.. Because of the time schedule placed on this effort It was decided to reduce the weight of the fourth-stage rocket-motor case by substituting the annealed 6Al--4V titanium alloy for the Type 410 stainless steel. Although this introduced an unfamiliar material, It reduced the changes in design and fabrication techniques. This particular titanium alloy was chosen on the basis of previous tests which proved the suitability of the alloy as a pressure-vessel material when used at an annealed yield strength of about 120, 000 psi. The titanium-case fourth stage of Juno U is shown with the payload and on the missile in Fig. 1; the stainless-steel motor cases used in the Jupiter-C vehicle are shown in Fig. 2. The fourth-stage motor case has a diameter of 6 in., a length of approximately 38 in. center dot and a nominal cylindrical wall thickness of 0.025 in. As shown in Fig. 1, the case serves as the structural support of the payload and is aligned to the upper stage assembly through an alignment ring. The nozzle is threaded into the end of the motor case, and is of the ceramic-coated steel design. Figure 3 shows a comparison of the

  3. Corrosion Analysis of an Experimental Noble Alloy on Commercially Pure Titanium Dental Implants

    PubMed Central

    Bortagaray, Manuel Alberto; Ibañez, Claudio Arturo Antonio; Ibañez, Maria Constanza; Ibañez, Juan Carlos

    2016-01-01

    Objective: To determine whether the Noble Bond® Argen® alloy was electrochemically suitable for the manufacturing of prosthetic superstructures over commercially pure titanium (c.p. Ti) implants. Also, the electrolytic corrosion effects over three types of materials used on prosthetic suprastructures that were coupled with titanium implants were analysed: Noble Bond® (Argen®), Argelite 76sf +® (Argen®), and commercially pure titanium. Materials and Methods: 15 samples were studied, consisting in 1 abutment and one c.p. titanium implant each. They were divided into three groups, namely: Control group: five c.p Titanium abutments (B&W®), Test group 1: five Noble Bond® (Argen®) cast abutments and, Test group 2: five Argelite 76sf +® (Argen®) abutments. In order to observe the corrosion effects, the surface topography was imaged using a confocal microscope. Thus, three metric parameters (Sa: Arithmetical mean height of the surface. Sp: Maximum height of peaks. Sv: Maximum height of valleys.), were measured at three different areas: abutment neck, implant neck and implant body. The samples were immersed in artificial saliva for 3 months, after which the procedure was repeated. The metric parameters were compared by statistical analysis. Results: The analysis of the Sa at the level of the implant neck, abutment neck and implant body, showed no statistically significant differences on combining c.p. Ti implants with the three studied alloys. The Sp showed no statistically significant differences between the three alloys. The Sv showed no statistically significant differences between the three alloys. Conclusion: The effects of electrogalvanic corrosion on each of the materials used when they were in contact with c.p. Ti showed no statistically significant differences. PMID:27733875

  4. Titanium integration with bone, welding, and screw head destruction complicating hardware removal of the distal radius: report of 2 cases.

    PubMed

    Van Nortwick, Sara S; Yao, Jeffrey; Ladd, Amy L

    2012-07-01

    Increasingly, surgeons treat distal radius fractures with locking plate systems. Recent case reports have focused on technical insertion errors resulting in removal difficulties: poor drilling orientation or cross-threading, destruction of the screw head, and filling of the screw recess with tissue. We report 2 complications of titanium locked plate removal secondary to in vivo reactions including titanium integration with bone and mechanical binding between the titanium screw and plate. We clarify and discuss terminology relevant to implant removal, including cold-welding, galling, fretting, and anodization. Even with optimal technique, in situ reactions can complicate titanium implant removal.

  5. [The effect of fluoride on electrochemical corrosion of the dental pure titanium before and after adhesion of Streptococcus mutans].

    PubMed

    Geng, Li; Qiao, Guang-yan; Gu, Kai-ka

    2016-04-01

    To investigate the effect of fluoride on electrochemical corrosion of the dental pure titanium before and after adhesion of Streptococcus mutans. The dental pure titanium specimens were tested by electrochemical measurement system including electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve (PD) methods in artificial saliva with 0 g/L and 1.0 g/L sodium fluoride before and after dipped into culture medium with Streptococcus mutans for 24 h. The corrosion parameters, including the polarization resistance (R(ct)), corrosion potential (E(corr)), pitting breakdown potential (E(b)), and the difference between E(corr) and E(b) representing the "pseudo-passivation" (ΔE) obtained from the electrochemical tests were used to evaluate the corrosion resistance of dental pure titanium. The data were statistically analyzed by 2×2 factorial statistical analysis to examine the effect of sodium fluoride and adhesion of Streptococcus mutans using SPSS 12.0 software package. The results showed that the corrosion parameters including R(ct), Ecorr, E(b), and ΔE of pure titanium had significant difference between before and after adhesion of Streptococcus mutans in the same solution(P<0.05), and in artificial saliva with 0 g/L and 1.0 g/L sodium fluoride(P<0.05). The dental pure titanium was prone to corrosion in artificial saliva with sodium fluoride. The corrosion resistance of pure titanium decreased distinctly after immersed in culture medium with Streptococcus mutans.

  6. Bactericidal and antimicrobial effects of pure titanium and titanium alloy treated with short-term, low-energy UV irradiation

    PubMed Central

    Narita, K.; Ono, A.; Wada, K.; Tanaka, T.; Kumagai, G.; Yamauchi, R.; Nakane, A.; Ishibashi, Y.

    2017-01-01

    Objectives The surface of pure titanium (Ti) shows decreased histocompatibility over time; this phenomenon is known as biological ageing. UV irradiation enables the reversal of biological ageing through photofunctionalisation, a physicochemical alteration of the titanium surface. Ti implants are sterilised by UV irradiation in dental surgery. However, orthopaedic biomaterials are usually composed of the alloy Ti6Al4V, for which the antibacterial effects of UV irradiation are unconfirmed. Here we evaluated the bactericidal and antimicrobial effects of treating Ti and Ti6Al4V with UV irradiation of a lower and briefer dose than previously reported, for applications in implant surgery. Materials and Methods Ti and Ti6Al4V disks were prepared. To evaluate the bactericidal effect of UV irradiation, Staphylococcus aureus 834 suspension was seeded onto the disks, which were then exposed to UV light for 15 minutes at a dose of 9 J/cm2. To evaluate the antimicrobial activity of UV irradiation, bacterial suspensions were seeded onto the disks 0, 0.5, one, six, 24 and 48 hours, and three and seven days after UV irradiation as described above. In both experiments, the bacteria were then harvested, cultured, and the number of colonies were counted. Results No colonies were observed when UV irradiation was performed after the bacteria were added to the disks. When the bacteria were seeded after UV irradiation, the amount of surviving bacteria on the Ti and Ti6Al4V disks decreased at 0 hours and then gradually increased. However, the antimicrobial activity was maintained for seven days after UV irradiation. Conclusion Antimicrobial activity was induced for seven days after UV irradiation on both types of disk. Irradiated Ti6Al4V and Ti had similar antimicrobial properties. Cite this article: T. Itabashi, K. Narita, A. Ono, K. Wada, T. Tanaka, G. Kumagai, R. Yamauchi, A. Nakane, Y. Ishibashi. Bactericidal and antimicrobial effects of pure titanium and titanium alloy treated with

  7. Joining aluminum to titanium alloy by friction stir lap welding with cutting pin

    SciTech Connect

    Wei, Yanni; Li, Jinglong; Xiong, Jiangtao; Huang, Fu; Zhang, Fusheng; Raza, Syed Hamid

    2012-09-15

    Aluminum 1060 and titanium alloy Ti-6Al-4V plates were lap joined by friction stir welding. A cutting pin of rotary burr made of tungsten carbide was employed. The microstructures of the joining interface were observed by scanning electron microscopy. Joint strength was evaluated by a tensile shear test. During the welding process, the surface layer of the titanium plate was cut off by the pin, and intensively mixed with aluminum situated on the titanium plate. The microstructures analysis showed that a visible swirl-like mixed region existed at the interface. In this region, the Al metal, Ti metal and the mixed layer of them were all presented. The ultimate tensile shear strength of joint reached 100% of 1060Al that underwent thermal cycle provided by the shoulder. - Highlights: Black-Right-Pointing-Pointer FSW with cutting pin was successfully employed to form Al/Ti lap joint. Black-Right-Pointing-Pointer Swirl-like structures formed due to mechanical mixing were found at the interface. Black-Right-Pointing-Pointer High-strength joints fractured at Al suffered thermal cycle were produced.

  8. Fiber laser welding of austenitic steel and commercially pure copper butt joint

    NASA Astrophysics Data System (ADS)

    Kuryntsev, S. V.; Morushkin, A. E.; Gilmutdinov, A. Kh.

    2017-03-01

    The fiber laser welding of austenitic stainless steel and commercially pure copper in butt joint configuration without filler or intermediate material is presented. In order to melt stainless steel directly and melt copper via heat conduction a defocused laser beam was used with an offset to stainless steel. During mechanical tests the weld seam was more durable than heat affected zone of copper so samples without defects could be obtained. Three process variants of offset of the laser beam were applied. The following tests were conducted: tensile test of weldment, intermediate layer microhardness, optical metallography, study of the chemical composition of the intermediate layer, fractography. Measurements of electrical resistivity coefficients of stainless steel, copper and copper-stainless steel weldment were made, which can be interpreted or recalculated as the thermal conductivity coefficient. It shows that electrical resistivity coefficient of cooper-stainless steel weldment higher than that of stainless steel. The width of intermediate layer between stainless steel and commercially pure copper was 41-53 μm, microhardness was 128-170 HV0.01.

  9. Effect of Friction Welding Condition on Joining Phenomena and Tensile Strength of Friction Welded joint between Pure Copper and Low Carbon Steel

    NASA Astrophysics Data System (ADS)

    Kimura, Masaaki; Kusaka, Masahiro; Kaizu, Koichi; Fuji, Akiyoshi

    This paper describes the effect of the friction welding condition on the joining phenomena and tensile strength of friction welded joint between pure copper (OFC) and low carbon steel (LCS). When the joint was made at friction pressure of 30 MPa with friction speed of 27.5 s-1, OFC transferred to the half radius region of the weld interface on the LCS side, and then transferred toward the entire weld interface. The temperatures at the centerline, half radius and periphery portions on the weld interface of the LCS side were almost the same after the initial peak. When the joint was made at a friction time of 2.4 s, i.e. the friction torque was close to the initial peak, that had obtained approximately 40% joint efficiency and fractured from the weld interface with a little OFC adhering to the weld interface on the LCS side. The joint efficiency increased with increasing forge pressure, and it reached approximately 80% at a forge pressure of 180 MPa. This joint fractured at the softened OFC region adjacent to the weld interface. On the other hand, OFC transferred to the peripheral region of the weld interface on the LCS side when the joint was made at friction pressure of 90 MPa with friction speed of 27.5 s-1. However, OFC transfer was not obtained at the central region because the temperature at the periphery portion was higher than that of the other portions. The joint efficiency increased with increasing friction time, and it obtained approximately 74% at a friction time of 1.2 s. Moreover, all joints fractured between the OFC side and the weld interface, although the joints were made with higher forge pressure. To obtain higher joint efficiency and fracture in the OFC side, the joint should be made with low friction pressure and high forge pressure, and with the friction time at which the friction torque reaches the initial peak.

  10. [The effect of fluoride on adhesion of Streptococcus mutans and Streptococcus sanguis on the dental pure titanium surface].

    PubMed

    Wang, Jue; Qiao, Guang-yan; Shen, Qing-ping; Gu, Kai-kai

    2015-04-01

    This study was to investigate the effect of fluoride on adhesion of Streptococcus mutans and Streptococcus sanguis on the dental pure titanium surface. The adhesion of Streptococcus mutans and Streptococcus sanguis on the dental pure titanium surface were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay after soaked in artificial saliva containing different concentrations of sodium fluoride for 24 h. Then the surface roughness and surface morphology of the pure titanium were analyzed by atomic force microscope after bacterial adhesion experiments. The data was statistically analyzed by analysis of variance(ANOVA) with SPSS11.0 software package. After soaked in artificial saliva containing different concentrations of sodium fluoride for 24 h, the sequence of OD values showed the adhesion of Streptococcus mutans and Streptococcus sanguis on dental pure titanium surface was 0 g/L < 0.5 g/L < 1.0g/L < 2.0 g/L (P<0.05). In addition, the sequence of Ra values showed the surface roughness of pure titanium after bacterial adhesion experiments was 0 g/L < 0.5 g/L < 1.0g/L < 2.0 g/L (P<0.05). And the surface morphology of pure titanium was consistent with the changes of OD value and Ra value. The results of adhesion of Streptococcus mutans and Streptococcus sanguis, surface roughness and surface morphology reveal that fluoride aggravates the corrosion of pure titanium, increases the surface roughness, and thus promots the adhesion of Streptococcus mutans and Streptococcus sanguis on the titanium surface.

  11. Corrosion-fatigue of laser-repaired commercially pure titanium and Ti-6Al-4V alloy under different test environments.

    PubMed

    Zavanelli, R A; Guilherme, A S; Pessanha-Henriques, G E; de Arruda Nóbilo, M Antônio; Mesquita, M F

    2004-10-01

    This study evaluated the corrosion-fatigue life of laser-repaired specimens fabricated from commercially pure titanium (CP Ti) and Ti-6Al-4V alloy, tested under different storage conditions. For each metal, 30 dumbbell rods with a central 2.3 mm diameter were prepared by lost-wax casting with the Rematitan System. Simulating the failure after service, corrosion-fatigue life in different media at room temperature (air, synthetic saliva and fluoride synthetic saliva) was determined at a testing frequency of 10 Hz for intact specimens and after laser repairing, using a square waveform with equal maximum tensile and compressive stress that was 30% lower than the 0.2% offset yield strength. For laser welding, the fractured specimens were rejoined using a jig to align the sections invested in type-IV dental stone. The adjacent areas of the gap was air-abraded with 100 microm aluminum oxide, laser welded and retested under the same conditions as the initial intact specimens. The number of cycles at failure was recorded, and the fracture surface was examined with a scanning electron microscope (SEM). The number of cycles for failure of the welded and intact specimens was compared by anova and the Tukey test at a 5% probability level. Within the limitations of this study, the number of cycles required for fracture decreased in wet environments and the laser repairing process adversely affected the life of both metals under the corrosion-fatigue conditions.

  12. Effects of fluoride and dissolved oxygen concentrations on the corrosion behavior of pure titanium and titanium alloys.

    PubMed

    Nakagawa, Masaharu; Matsuya, Shigeki; Udoh, Koichi

    2002-06-01

    The effects of dissolved-oxygen concentration and fluoride concentration on the corrosion behaviors of commercial pure titanium, Ti-6Al-4V and Ti-6Al-7Nb alloys and experimentally produced Ti-0.2Pd and Ti-0.5Pt alloys were examined using the corrosion potential measurements. The amount of dissolved Ti was analyzed by inductively coupled plasma mass spectroscopy. A decrease in the dissolved-oxygen concentration tended to reduce the corrosion resistance of Ti and Ti alloys. If there was no fluoride, however, corrosion did not occur. Under low dissolved-oxygen conditions, the corrosion of pure Ti and Ti-6Al-4V and Ti-6Al-7Nb alloys might easily take place in the presence of small amounts of fluoride. They were corroded by half or less of the fluoride concentrations in commercial dentifrices. The Ti-0.2Pd and Ti-0.5Pt alloys did not corrode more, even under the low dissolved-oxygen conditions and a fluoride-containing environment, than pure Ti and Ti-6Al-4V and Ti-6Al-7Nb alloys. These alloys are expected to be useful as new Ti alloys with high corrosion resistance in dental use.

  13. Strain localization of commercially pure titanium subjected to ultrasonic impact treatment followed by uniaxial tension

    NASA Astrophysics Data System (ADS)

    Panin, Alexey; Kazachenok, Marina; Kozelskaya, Anna; Perevalova, Olga; Balokhonov, Ruslan; Romanova, Varvara; Pochivalov, Yurii

    2016-11-01

    It was demonstrated that the ultrasonic impact treatment results in the gradient microstructure of the surface layer of commercially pure titanium composed of nanosized nonequiaxial α-Ti grains, underlying course α-grains with banded substructure and deformation twins, and subjacent layer characterized by the presence of a few twins and extinction contours within the course grains. The effect of ultrasonic impact treatment on the mechanical behavior of titanium specimen under tension was revealed theoretically and experimentally Using optical and atomic force microscopes it was shown that the fine-grained surface layer impede dislocation motion causing the initiation and propagation of shear bands oriented along the direction of maximum shear stresses. The fine structure of shear bands was studied by transmission electron microscopy.

  14. Optimization of Oxidation Temperature for Commercially Pure Titanium to Achieve Improved Corrosion Resistance

    NASA Astrophysics Data System (ADS)

    Bansal, Rajesh; Singh, J. K.; Singh, Vakil; Singh, D. D. N.; Das, Parimal

    2017-03-01

    Thermal oxidation of commercially pure titanium (cp-Ti) was carried out at different temperatures, ranging from 200 to 900 °C to achieve optimum corrosion resistance of the thermally treated surface in simulated body fluid. Scanning electron microscopy, x-ray diffraction, Raman spectroscopy and electrochemical impedance spectroscopy techniques were used to characterize the oxides and assess their protective properties exposed in the test electrolyte. Maximum resistance toward corrosion was observed for samples oxidized at 500 °C. This was attributed to the formation of a composite layer of oxides at this temperature comprising Ti2O3 (titanium sesquioxide), anatase and rutile phases of TiO2 on the surface of cp-Ti. Formation of an intact and pore-free oxide-substrate interface also improved its corrosion resistance.

  15. Optimization of Oxidation Temperature for Commercially Pure Titanium to Achieve Improved Corrosion Resistance

    NASA Astrophysics Data System (ADS)

    Bansal, Rajesh; Singh, J. K.; Singh, Vakil; Singh, D. D. N.; Das, Parimal

    2017-02-01

    Thermal oxidation of commercially pure titanium (cp-Ti) was carried out at different temperatures, ranging from 200 to 900 °C to achieve optimum corrosion resistance of the thermally treated surface in simulated body fluid. Scanning electron microscopy, x-ray diffraction, Raman spectroscopy and electrochemical impedance spectroscopy techniques were used to characterize the oxides and assess their protective properties exposed in the test electrolyte. Maximum resistance toward corrosion was observed for samples oxidized at 500 °C. This was attributed to the formation of a composite layer of oxides at this temperature comprising Ti2O3 (titanium sesquioxide), anatase and rutile phases of TiO2 on the surface of cp-Ti. Formation of an intact and pore-free oxide-substrate interface also improved its corrosion resistance.

  16. The effect of thermal cycling on the bond strength of low-fusing porcelain to commercially pure titanium and titanium-aluminium-vanadium alloy.

    PubMed

    Tróia, Manoel G; Henriques, Guilherme E P; Nóbilo, Mauro A A; Mesquita, Marcelo F

    2003-12-01

    Titanium-ceramic restorations are currently used in spite of the pending problem of titanium-ceramic bonding, which has only been partially solved. In addition, some titanium-ceramic systems appear to be susceptible to thermal cycling, which can cause weaker bond strength. The objective of this study was to evaluate the bonding characteristics of titanium porcelain bonded to commercially pure titanium (Ti-Cp) or titanium-aluminum-vanadium (Ti-6Al-4V) alloy as well as the effect of thermal cycling on bond strength. A three-point-flexure-test was used to evaluate the bond strength of titanium porcelain bonded to commercially pure titanium and Ti-6Al-4V alloy according to DIN 13.927. To evaluate the effect of thermal cycling on the samples, half were thermal cycled in temperatures ranging from 4 degrees C (+/-2 degrees C) to 55 degrees C (+/-2 degrees C). Results were compared with palladium-silver (Pd-Ag) alloy bonded to conventional porcelain (control). Scanning electron microscope (SEM) photomicrographs were taken to characterize the failed surfaces in the metal-ceramic interface. Anova and Tukey's multiple comparison tests were used to analyze the data at a 5% probability level. Thermal cycling did not significantly weaken the bond strength of porcelain to titanium interfaces. There was no significant difference in bond strength between commercially pure titanium (23.60 MPa for thermal cycled group and 24.99 MPa for non-thermal cycled group) and Ti-6Al-4V groups (24.98 and 25.60 MPa for thermal cycled and non-thermal cycled groups, respectively). Bond strength values for the control group (47.98 and 45.30 MPa, respectively) were significantly greater than those for commercially pure titanium and Ti-6Al-4V combinations. The bond strength of low fusing porcelain bonded to cast pure titanium or Ti-6Al-4V alloy was significantly lower than the conventional combination of porcelain-Pd-Ag alloy. Thermal cycling did not affect the bond strength of any group.

  17. Investigation of plasma arc welding as a method for the additive manufacturing of titanium-(6)aluminum-(4)vanadium alloy components

    NASA Astrophysics Data System (ADS)

    Stavinoha, Joe N.

    The process of producing near net-shape components by material deposition is known as additive manufacturing. All additive manufacturing processes are based on the addition of material with the main driving forces being cost reduction and flexibility in both manufacturing and product design. With wire metal deposition, metal is deposited as beads side-by-side and layer-by-layer in a desired pattern to build a complete component or add features on a part. There are minimal waste products, low consumables, and an efficient use of energy and feedstock associated with additive manufacturing processes. Titanium and titanium alloys are useful engineering materials that possess an extraordinary combination of properties. Some of the properties that make titanium advantageous for structural applications are its high strength-to-weight ratio, low density, low coefficient of thermal expansion, and good corrosion resistance. The most commonly used titanium alloy, Ti-6Al-4V, is typically used in aerospace applications, pressure vessels, aircraft gas turbine disks, cases and compressor blades, and surgical implants. Because of the high material prices associated with titanium alloys, the production of near net-shape components by additive manufacturing is an attractive option for the manufacturing of Ti-6Al-4V alloy components. In this thesis, the manufacturing of cylindrical Ti-6Al-4V alloy specimens by wire metal deposition utilizing the plasma arc welding process was demonstrated. Plasma arc welding is a cost effective additive manufacturing technique when compared to other current additive manufacturing methods such as laser beam welding and electron beam welding. Plasma arc welding is considered a high-energy-density welding processes which is desirable for the successful welding of titanium. Metal deposition was performed using a constant current plasma arc welding power supply, flow-purged welding chamber, argon shielding and orifice gas, ERTi-5 filler metal, and Ti-6Al

  18. Biocompatibility of surface treated pure titanium and titanium alloy by in vivo and in vitro test

    NASA Astrophysics Data System (ADS)

    Lee, Min-Ho; Yoon, Dong-Joo; Won, Dae-Hee; Bae, Tae-Sung; Watari, Fumio

    2003-02-01

    In the present study, commercial pure Ti and Ti-6Al-4V alloy specimens with and without alkali and heat treatments were implanted in the abdominal connective tissue of mice. Conventional stainless steel 316L was also implanted for comparison. After three months, their biocompatibility was evaluated by in vitro and in vivo experiments. Surface structural changes of specimens due to the alkali treatment and soaking in Hank's solution were analyzed by XRD, SEM, XPS and AES. An apatite layer, which accelerates the connection with bone, was formed more easily on the alkali treated specimens than the non-treated specimens. The number of macrophages, which is known to increase as the inflammatory reaction proceeds, was much lower for the alkali and heat treated specimens than for the others. The average thickness of the fibrous capsule formed around the implant was much thinner for the alkali and heat treated specimens than for the others.

  19. Characteristics and Corrosion Behavior of Pure Titanium Subjected to Surface Mechanical Attrition

    NASA Astrophysics Data System (ADS)

    Fu, Tianlin; Wang, Xiao; Liu, Jianxiong; Li, Li; Yu, Xiaohua; Zhan, Zhaolin

    2017-08-01

    A stable passive film exhibiting good corrosion resistance in a 3.5 wt.% NaCl solution was formed on the surface of pure titanium (Ti) subjected to a surface mechanical attrition treatment (SMAT). The corrosion potential (-0.21 V) of the film was significantly higher than that (-0.92 V) of the untreated sample. Moreover, the corrosion current density was an order of magnitude lower than that of the untreated sample. SMAT resulted in a decrease in the vacancy condensation in the TiO2 film, thereby inhibiting the invasion and diffusion of Cl- in the film.

  20. Characteristics and Corrosion Behavior of Pure Titanium Subjected to Surface Mechanical Attrition

    NASA Astrophysics Data System (ADS)

    Fu, Tianlin; Wang, Xiao; Liu, Jianxiong; Li, Li; Yu, Xiaohua; Zhan, Zhaolin

    2017-10-01

    A stable passive film exhibiting good corrosion resistance in a 3.5 wt.% NaCl solution was formed on the surface of pure titanium (Ti) subjected to a surface mechanical attrition treatment (SMAT). The corrosion potential (-0.21 V) of the film was significantly higher than that (-0.92 V) of the untreated sample. Moreover, the corrosion current density was an order of magnitude lower than that of the untreated sample. SMAT resulted in a decrease in the vacancy condensation in the TiO2 film, thereby inhibiting the invasion and diffusion of Cl- in the film.

  1. Spherical nanoindentation stress-strain curves of commercially pure titanium and Ti-6Al-4V

    DOE Data Explorer

    Weaver, Jordan S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Priddy, Matthew W. [Georgia Inst. of Technology, Atlanta, GA (United States); McDowell, David L. [Georgia Inst. of Technology, Atlanta, GA (United States); Kalidindi, Surya R. [Georgia Inst. of Technology, Atlanta, GA (United States)

    2016-07-27

    Spherical nanoindentation combined with electron back-scattered diffraction was employed to characterize the grain-scale elastic and plastic anisotropy of single crystal alpha-Ti for commercially pure (CP-Ti) and alloyed (Ti-64) titanium. In addition, alpha-beta Ti (single colony) grains were characterized. The data set includes the nanoindentation force, displacement, and contact stiffness, the nanoindentation stress-strain analysis, and the alpha-Ti crystal orientations. Details of the samples and experimental protocols can be found in Weaver et al. (2016) Acta Materialia doi:10.1016/j.actamat.2016.06.053.

  2. Work-hardening behavior of commercially pure titanium JIS grade 1 sheet upon reverse loading

    NASA Astrophysics Data System (ADS)

    Hama, Takayuki; Yi, Ning; Kobuki, Akihiro; Uchida, Sohei; Fujimoto, Hitoshi; Takuda, Hirohiko

    2016-10-01

    In the present study, work-hardening behavior under various loading paths of a commercially pure titanium JIS Grade 1 sheet was investigated. The following tension-compression asymmetry was presented. The yield stress was smaller under compression than under tension, whereas the subsequent work-hardening was larger under compression than under tension. When the sheet was subjected to reverse loading from compression to tension, strong Bauschinger effect was exhibited. Thereafter, a concave curve followed by a small stress peak appeared, which was not presented under monotonic tension. Microstructure observations suggested that this characteristic behavior would be owing to the the activities of twinning and detwinning respectively during compression and following tension.

  3. [Titanium joints welded with laser and infrared techniques: comparative analysis of its microstructure].

    PubMed

    Manicone, P; Valentini, G; Raffaelli, L; Raffaelli, R

    2000-10-01

    Aim of the study is to compare microstructure of Titanium joints soldered with Laser and Infrared methods by performing SEM analysis, metallography and microhardness evaluation. Wax specimens were separated in the middle area corresponding to the joint region, machined and then soldered. 40 Titanium samples were fused and divided in 2 groups of 20 samples each. First group was soldered by laser welding, second one by infrared brazing. SEM analysis and standard metallography were carried out at joined areas and unsoldered surfaces. Microhardness test was performed on longitudinally sectioned samples with 150 g load for 15 second up to 7 mm distance from the joined area. SEM photomicrographs revealed for group 1 a homogeneous metal-joint interface, without microporosities; for group 2 exhibited a distinct demarcation of metal joint interface. Metallography evaluation showed for laser joined samples only the presence of Titanium; infrared joined samples showed in soldered regions also Ni and Cu. Microhardness values detected at the joined surfaces seem to be higher for both considered groups. Laser joining method with exclusive presence of Titanium seems to be ideal for monometallism; both techniques exhibited microstructural changes in the heated surface layer.

  4. Investigation of the vapour-plasma plume in the welding of titanium by high-power ytterbium fibre laser radiation

    SciTech Connect

    Bykovskiy, D P; Petrovskii, V N; Uspenskiy, S A

    2015-03-31

    The vapour-plasma plume produced in the welding of 6-mm thick VT-23 titanium alloy plates by ytterbium fibre laser radiation of up to 10 kW power is studied in the protective Ar gas medium. High-speed video filming of the vapour-plasma plume is used to visualise the processes occurring during laser welding. The coefficient of inverse bremsstrahlung by the welding plasma plume is calculated from the data of the spectrometric study. (interaction of laser radiation with matter)

  5. Cytocompatibility of pure metals and experimental binary titanium alloys for implant materials.

    PubMed

    Park, Yeong-Joon; Song, Yo-Han; An, Ji-Hae; Song, Ho-Jun; Anusavice, Kenneth J

    2013-12-01

    This study was performed to evaluate the biocompatibility of nine types of pure metal ingots (Ag, Al, Cr, Cu, Mn, Mo, Nb, V, Zr) and 36 experimental titanium (Ti) alloys containing 5, 10, 15, and 20 wt% of each alloying element. The cell viabilities for each test group were compared with that of CP-Ti using the WST-1 test and agar overlay test. The ranking of pure metal cytotoxicity from most potent to least potent was as follows: Cu>Al>Ag>V>Mn>Cr>Zr>Nb>Mo>CP-Ti. The mean cell viabilities for pure Cu, Al, Ag, V, and Mn were 21.6%, 25.3%, 31.7%, 31.7%, and 32.7%, respectively, which were significantly lower than that for the control group (p<0.05). The mean cell viabilities for pure Zr and Cr were 74.1% and 60.6%, respectively (p<0.05). Pure Mo and Nb demonstrated good biocompatibility with mean cell viabilities of 93.3% and 93.0%, respectively. The mean cell viabilities for all the Ti-based alloy groups were higher than 80% except for Ti-20 Nb (79.6%) and Ti-10 V (66.9%). The Ti-10 Nb alloy exhibited the highest cell viability (124.8%), which was higher than that of CP-Ti. Based on agar overlay test, pure Ag, Cr, Cu, Mn, and V were ranked as 'moderately cytotoxic', whereas the rest of the tested pure metals and all Ti alloys, except Ti-10 V (mild cytotoxicity), were ranked as 'noncytotoxic'. The results obtained in this study can serve as a guide for the development of new Ti-based alloy implant systems. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Microstructure and properties of laser-borided composite layers formed on commercially pure titanium

    NASA Astrophysics Data System (ADS)

    Kulka, M.; Makuch, N.; Dziarski, P.; Piasecki, A.; Miklaszewski, A.

    2014-03-01

    Laser-boriding was proposed in order to produce composite boride layers on commercially pure titanium. Three zones were observed in the microstructure: laser-borided re-melted zone (TiB, TiB2 and Tiα'-phase), heat affected zone (Tiα'-phase) and the substrate without heat treatment (Tiα-phase). The stick-like titanium borides occurred in the re-melted zone. In some areas, the tubular nature of titanium borides was visible. Among the sticks of titanium borides the needles of Tiα'-phase appeared. The high overlapping of multiple laser tracks (86%) caused the formation of uniform laser-alloyed layer in respect of the thickness. The microcracks and pores were not detected in the laser-borided composite layer. The high hardness of the re-melted zone (1250-1650 HV) was obtained. The hardness gradually decreased up to 250-300 HV in heat affected zone and up to about 200 HV in the substrate. In case of higher laser beam power used (1.95 kW), the re-melted zone was thicker and more homogeneous in respect of the microstructure and hardness. The craters obtained at the surface after the Rockwell C indentation test evidently revealed ideal cohesion of the laser-borided layer (HF1 standard). The significant increase in wear resistance of laser-borided composite layers was observed in comparison with commercially pure titanium. The lower mass wear intensity factors were obtained for laser-alloyed layers. The measurements of relative mass loss were also used in order to evaluate wear behavior of the investigated materials. The tests of laser-borided layers showed the catastrophic wear of the counter-specimens. The separated particles of counter-sample caused the accelerated wear of the laser-alloyed specimen. The longer duration of the tests, carried out without the change in a counter-specimen, caused the adhesion of counter-sample particles on the laser-borided specimen. The increased contact surface was the reason for the higher temperature and created the favourable

  7. Effect of plasma nitriding treatment on structural, tribological and electrochemical properties of commercially pure titanium.

    PubMed

    Çelik, İlhan; Karakan, Mehmet

    2016-02-01

    In this study, plasma nitriding treatment was applied to commercially pure titanium (Grade 2). Structural properties, electrochemical and tribological behaviours of the nitrided pure titanium specimens were comparatively investigated. Microstructure and morphology of the plasma nitrided specimens were analysed by X-ray diffraction and scanning electron microscopy. Furthermore, corrosion tests were conducted in Ringer's solution, which represents a human body environment, to determine electrochemical properties. Then, tribological and frictional properties were investigated using pin-on-disc tribometer, and a micro-hardness tester was used to measure the hardness of the coatings. The results showed that plasma nitrided specimens exhibited higher surface hardness than the untreated specimens did. In addition, the plasma nitrided specimens at 700 °C presented significantly better performance than the other plasma nitrided specimens (at 500 °C and 600 °C) under dry wear conditions. Moreover, corrosion test results showed that corrosion behaviours of untreated and nitrided samples had similar characteristic. © IMechE 2015.

  8. ARc Welding (Industrial Processing Series).

    DTIC Science & Technology

    ARC WELDING , *BIBLIOGRAPHIES), (*ARC WELDS, BIBLIOGRAPHIES), ALUMINUM ALLOYS, TITANIUM ALLOYS, CHROMIUM ALLOYS, METAL PLATES, SPOT WELDING , STEEL...INERT GAS WELDING , MARAGING STEELS, MICROSTRUCTURE, HEAT RESISTANT ALLOYS, HEAT RESISTANT METALS, WELDABILITY, MECHANICAL PROPERTIES, MOLYBDENUM ALLOYS, NICKEL ALLOYS, RESISTANCE WELDING

  9. Laser-Arc Hybrid Welding of Dissimilar Titanium Alloy and Stainless Steel Using Copper Wire

    NASA Astrophysics Data System (ADS)

    Gao, Ming; Chen, Cong; Wang, Lei; Wang, Zemin; Zeng, Xiaoyan

    2015-05-01

    Laser-arc hybrid welding with Cu3Si filler wire was employed to join dissimilar Ti6Al4V titanium alloy and AISI316 stainless steel (316SS). The effects of welding parameters on bead shape, microstructure, mechanical properties, and fracture behavior were investigated in detail. The results show that cross-weld tensile strength of the joints is up to 212 MPa. In the joint, obvious nonuniformity of the microstructure is found in the fusion zone (FZ) and at the interfaces from the top to the bottom, which could be improved by increasing heat input. For the homogeneous joint, the FZ is characterized by Fe67- x Si x Ti33 dendrites spreading on α-Cu matrix, and the two interfaces of 316SS/FZ and FZ/Ti6Al4V are characterized by a bamboo-like 316SS layer and a CuTi2 layer, respectively. All the tensile samples fractured in the hardest CuTi2 layer at Ti6Al4V side of the joints. The fracture surface is characterized by river pattern revealing brittle cleavage fracture. The bead formation mechanisms were discussed according to the melt flow and the thermodynamic calculation.

  10. Tensile properties of a titanium modified austenitic stainless steel and the weld joints after neutron irradiation

    SciTech Connect

    Shiba, Kiyoyuki; Ioka, Ikuo; Jitsukawa, Shiro; Hamada, Shozo; Hishinuma, Atkinichi; Robertson, J.P.

    1999-10-01

    Tensile specimens of a titanium modified austenitic stainless steel and its weldments fabricated with Tungsten Inert Gas (TIG) and Electron Beam (EB) welding techniques were irradiated to a peak dose of 19 dpa and a peak helium level of 250 appm in the temperature range between 200 and 400 C in spectrally tailored capsules in the Oak Ridge Research Reactor (ORR) and the High Flux Isotope Reactor (HFIR). The He/dpa ratio of about 13 appm/dpa is similar to the typical helium/.dpa ratio of a fusion reactor environment. The tensile tests were carried out at the irradiation temperature in vacuum. The irradiation caused an increase in yield stress to levels between 670 and 800 MPa depending on the irradiation temperature. Total elongation was reduced to less than 10%, however the specimens failed in a ductile manner. The results were compared with those of the specimens irradiated using irradiation capsules producing larger amount of He. Although the He/dpa ratio affected the microstructural change, the impact on the post irradiation tensile behavior was rather small not only for base metal specimens but also for the weld joint and the weld metal specimens.

  11. Tensile properties of a titanium modified austenitic stainless steel and the weld joints after neutron irradiation

    SciTech Connect

    Shiba, K.; Ioka, I.; Jitsukawa, S.; Hamada, A.; Hishinuma, A.

    1996-10-01

    Tensile specimens of a titanium modified austenitic stainless steel and its weldments fabricated with Tungsten Inert Gas (TIG) and Electron Beam (EB) welding techniques were irradiated to a peak dose of 19 dpa and a peak helium level of 250 appm in the temperature range between 200 and 400{degrees}C in spectrally tailored capsules in the Oak Ridge Research Reactor (ORR) and the High Flux Isotope Reactor (HFIR). The He/dpa ratio of about 13 appm/dpa is similar to the typical helium/dpa ratio of a fusion reactor environment. The tensile tests were carried out at the irradiation temperature in vacuum. The irradiation caused an increase in yield stress to levels between 670 and 800 MPa depending on the irradiation temperature. Total elongation was reduced to less than 10%, however the specimens failed in a ductile manner. The results were compared with those of the specimens irradiated using irradiation capsules producing larger amount of He. Although the He/dpa ratio affected the microstructural change, the impact on the post irradiation tensile behavior was rather small for not only base metal specimens but also for the weld joint and the weld metal specimens.

  12. Effects of sandblasting and electrical discharge machining on porcelain adherence to cast and machined commercially pure titanium.

    PubMed

    Inan, Ozgür; Acar, Asli; Halkaci, Selçuk

    2006-08-01

    The aim of this study was to determine the effect of sandblasting and electrical discharge machining (EDM) on cast and machined titanium surfaces and titanium-porcelain adhesion. Twenty machined titanium specimens were prepared by manufacturer (groups 1 and 2). Thirty specimens were prepared with autopolymerizing acrylic resin. Twenty of these specimens (groups 3 and 4) were cast with commercially pure titanium and the alpha-case layer was removed. For control group (group 5), 10 specimens were cast by using NiCr alloy. Groups 2 and 4 were subjected to EDM while groups 1, 3, and 5 were subjected to sandblasting. Surface examinations were made by using a scanning electron microscope (SEM). A low-fusing porcelain was fused on the titanium surfaces, whereas NiCr specimens were covered using a conventional porcelain. Titanium-porcelain adhesion was characterized by a 3-point bending test. Results were analyzed by Kruskal-Wallis and Mann-Whitney U tests. Metal-porcelain interfaces were characterized by SEM. The bond strength of control group was higher than that of the titanium-porcelain system. There was no significant difference between cast and machined titanium groups (p > 0.05). There was no significant difference between EDM and sandblasting processes (p > 0.05). The use of EDM as surface treatment did not improve titanium-porcelain adhesion compared with sandblasting.

  13. [Research on investing methods and mold cooling methods of the self-made investment for pure titanium castings].

    PubMed

    Zhao, Juan; Huang, Xu; Zhao, Yun-Feng; Xiao, Mao-Chun; Li, Yong

    2006-10-01

    To observe the influence of different investing methods and mold cooling methods on pure titanium castings invested in the self-made investment, and to provide theoretic base for the development for the investment. The influence of investing methods (one-step investing method and two-step investing method) on castability and crown fit of titanium castings were investigated, and the influence of cooling methods on reaction layers, mechanical properties and crown fit of titanium castings were investigated. Both the investing methods exhibited good castability, but only the titanium full crowns by one-step investing method showed clinically acceptable fit. Although the quenching group showed thinner reaction layer(100 microm), lower strength and similar elongation rate, the titanium castings by bench cooling showed clinically acceptable full crown fit with 115 microm thick reaction layer as cast. The one-step investing method and the bench cooling are recommended for the self-made investment.

  14. DC electrical conductivity measurements for pure and titanium oxide doped KDP Crystals grown by gel medium

    NASA Astrophysics Data System (ADS)

    Mareeswaran, S.; Asaithambi, T.

    2016-10-01

    Now a day's crystals are the pillars of current technology. Crystals are applied in various fields like fiber optic communications, electronic industry, photonic industry, etc. Crystal growth is an interesting and innovative field in the subject of physics, chemistry, material science, metallurgy, chemical engineering, mineralogy and crystallography. In recent decades optically good quality of pure and metal doped KDP crystals have been grown by gel growth method in room temperature and its characterizations were studied. Gel method is a very simple and one of the easiest methods among the various crystal growth methods. Potassium dihydrogen phosphate KH2PO4 (KDP) continues to be an interesting material both academically and technologically. KDP is a delegate of hydrogen bonded materials which possess very good electrical and nonlinear optical properties in addition to interesting electro-optic properties. We made an attempt to grow pure and titanium oxide doped KDP crystals with various doping concentrations (0.002, 0.004, 0.006, 0.008 and 0.010) using gel method. The grown crystals were collected after 20 days. We get crystals with good quality and shaped crystals. The dc electrical conductivity (resistance, capacitance and dielectric constant) values of the above grown crystals were measured at two different frequencies (1KHz and 100 Hz) with a temperature range of 500C to 1200C using simple two probe setup with Q band digital LCR meter present in our lab. The electrical conductivity increases with the increase of temperature. Dielectric constants value of titanium oxide doped KDP crystal was slightly decreased compared with pure KDP crystals. Results were discussed in details.

  15. Is there scientific evidence favoring the substitution of commercially pure titanium with titanium alloys for the manufacture of dental implants?

    PubMed

    Cordeiro, Jairo M; Barão, Valentim A R

    2017-02-01

    The development of Ti alloys to manufacture dental implants has emerged in recent years due to the increased failure of commercially pure titanium (cpTi) implants. Thus, this study reviews existing information about the mechanical, chemical, electrochemical, and biological properties of the main Ti alloys developed over the past few years to provide scientific evidence in favor of using Ti-based alloys as alternative to cpTi. Ti alloys may be considered viable substitutes in the fabrication of dental implants. Such evidence is given by the enhanced properties of alloys, such as a low elastic modulus, high tensile strength, satisfactory biocompatibility, and good corrosion and wear resistances. In addition, Ti alloys may be modified at the structural, chemical, and thermomechanical levels, which allows the development of materials in accordance with the demands of several situations encountered in clinical practice. Although several in vitro studies have established the superiority of Ti alloys over cpTi, mainly in terms of their mechanical properties, there is no scientific evidence that supports the total replacement of this material in vivo. This review demonstrates the superiority of β-type alloys. However, it is evident that in vivo studies are encouraged to test new alloys to consolidate their use as substitutes for cpTi.

  16. Full-Field Strain Measurement On Titanium Welds And Local Elasto-Plastic Identification With The Virtual Fields Method

    SciTech Connect

    Tattoli, F.; Casavola, C.; Pierron, F.; Rotinat, R.; Pappalettere, C.

    2011-01-17

    One of the main problems in welding is the microstructural transformation within the area affected by the thermal history. The resulting heterogeneous microstructure within the weld nugget and the heat affected zones is often associated with changes in local material properties. The present work deals with the identification of material parameters governing the elasto--plastic behaviour of the fused and heat affected zones as well as the base material for titanium hybrid welded joints (Ti6Al4V alloy). The material parameters are identified from heterogeneous strain fields with the Virtual Fields Method. This method is based on a relevant use of the principle of virtual work and it has been shown to be useful and much less time consuming than classical finite element model updating approaches applied to similar problems. The paper will present results and discuss the problem of selection of the weld zones for the identification.

  17. Full-Field Strain Measurement On Titanium Welds And Local Elasto-Plastic Identification With The Virtual Fields Method

    NASA Astrophysics Data System (ADS)

    Tattoli, F.; Pierron, F.; Rotinat, R.; Casavola, C.; Pappalettere, C.

    2011-01-01

    One of the main problems in welding is the microstructural transformation within the area affected by the thermal history. The resulting heterogeneous microstructure within the weld nugget and the heat affected zones is often associated with changes in local material properties. The present work deals with the identification of material parameters governing the elasto—plastic behaviour of the fused and heat affected zones as well as the base material for titanium hybrid welded joints (Ti6Al4V alloy). The material parameters are identified from heterogeneous strain fields with the Virtual Fields Method. This method is based on a relevant use of the principle of virtual work and it has been shown to be useful and much less time consuming than classical finite element model updating approaches applied to similar problems. The paper will present results and discuss the problem of selection of the weld zones for the identification.

  18. Microstructure evolution and material flow behavior in friction-stir welded dissimilar titanium alloys

    NASA Astrophysics Data System (ADS)

    Gonser, Matthew J.

    The purpose of this study was to friction-stir weld dissimilar titanium alloys together and to investigate how macroscopic flow in the stir zone and the resulting weld microstructure affect mechanical properties. Welds were produced with travel speeds from 50 to 100 mm/min and tool rotation speeds of 2000 to 3500 revolutions per minute (RPM). Thermal analysis showed that super transus temperatures were reached in the stir zone and both near-HAZ regions of the weld. Cooling rate data was consistent with the formation of basketweave and colony alpha phase in the prior-beta grains on the Ti-6Al-4V side of the stir zone and near-HAZ. The Timetal 21S region of the stir zone consisted of refined (approximately 18 mum in diameter) metastable-beta grains compared to 30 mum diameter grains in the Timetal 21S base material. Metallurgical mixing between the two alloys resulted in a unique alpha-beta microstructure in the stir zone. The amount of metallurgical mixing was found to be dependent on which alloy was placed on the retreating side of the weld. With the FSW tool centered between the two materials, placement of the Ti-6Al-4V alloy on the retreating side increased the amount of metallurgical mixing between the two alloys by 40% compared to when the Timetal 21S was placed on the retreating side. Electron back-scatter diffraction (EBSD) clearly showed the presence of a TMAZ adjacent to the stir zone on the Timetal 21S side of the weld. This was confirmed by the large number of low angle subgrains (misorientation angle<10°) within the deformed metastable-beta matrix. The stir zone was shown to have fewer subgrains due to the recrystallization of new grains which consume the recovered metastable-beta matrix. A series of aging and solution treatment plus aging heat treatments was given to select as-welded samples to investigate the change in microstructure and properties. The peak hardness for all regions was obtained for the 500°C-8 hour heat treatment, while the 600°C-8

  19. Preparation and properties of plasma electrolytic oxidation coating on sandblasted pure titanium by a combination treatment.

    PubMed

    Wang, Hong-Yuan; Zhu, Rui-Fu; Lu, Yu-Peng; Xiao, Gui-Yong; Zhao, Xing-Chuan; He, Kun; Yuan, Y F; Li, Ying; Ma, Xiao-Ni

    2014-09-01

    Plasma electrolytic oxidation (PEO) is one of the most applicable methods to produce bioceramic coating on a dental implant and sandblasting is a primary technique to modify metal surface properties. This study aims to deposit bioceramic Ca- and P-containing coatings on sandblasted commercially pure titanium by PEO technique to improve its bioactive performance. The time-dependent modified surfaces are characterized in terms of their microstructure, phase, chemical composition, mechanical properties and bioactivities. The results show that the combination-treated coating exhibits better properties than the PEO-treated one, especially in bioactivities, as evidenced by the HA formation after immersion in simulated body fluid (SBF) for 5 days and the cell viability after seeding for 1 or 3 days. The enhancement of the modified surface is attributed to a combination of the mechanical sandblasting and the microplasma oxidation.

  20. Influence of oxidation treatment on fatigue and fatigue-induced damage of commercially pure titanium.

    PubMed

    Leinenbach, C; Eifler, D

    2009-09-01

    In this investigation, the cyclic deformation behaviour of commercially pure titanium was characterized in axial stress controlled constant amplitude and load increase tests, as well as in rotating bending tests. The influence of different clinically relevant surface treatments (polishing, thermal and anodic oxidizing) on the fatigue behaviour was investigated. All tests were realized in oxygen-saturated Ringer's solution. The cyclic deformation behaviour was characterized by mechanical hysteresis measurements. In addition, the change of the free corrosion potential and the corrosion current during the fatigue tests in simulated physiological media indicated such types of surface damage as slip bands, microcracks and oxide film ablation. Microstructural changes on the specimen surfaces were examined by scanning electron microscopy.

  1. The process development of laser surface modification of commercially pure titanium (Grade 2) with rhenium

    NASA Astrophysics Data System (ADS)

    Kobiela, K.; Smolina, I.; Dziedzic, R.; Szymczyk, P.; Kurzynowski, T.; Chlebus, E.

    2016-12-01

    The paper presents the results of the process development of laser surface modification of commercially pure titanium with rhenium. The criterion of the successful/optimal process is the repetitive geometry of the surface, characterized by predictable and repetitive chemical composition over its entire surface as well as special mechanical properties (hardness and wear resistance). The analysis of surface geometry concluded measurements of laser penetration depth and heat affected zone (HAZ), the width of a single track as well as width of a clad. The diode laser installed on the industrial robot carried out the laser treatment. This solution made possible the continuous supply of powder to the substrate during the process. The aim of an investigation is find out the possibility of improving the tribological characteristics of the surface due to the rhenium alloying. The verification of the surface properties (tribological) concluded geometry measurements, microstructure observation, hardness tests and evaluation of wear resistance.

  2. Effect of Thermal Oxidation on Corrosion Resistance of Commercially Pure Titanium in Acid Medium

    NASA Astrophysics Data System (ADS)

    Jamesh, M.; Kumar, Satendra; Sankara Narayanan, T. S. N.

    2012-06-01

    This article addresses the characteristics of commercially pure titanium (CP-Ti) subjected to thermal oxidation in air at 650 °C for 48 h and its corrosion behavior in 0.1 and 4 M HCl and HNO3 mediums. Thermal oxidation of CP-Ti leads to the formation of thick oxide scales (~20 μm) throughout its surface without any spallation. The oxide layer consists of rutile- and oxygen-diffused titanium as predominant phases with a hardness of 679 ± 43 HV1.96. Electrochemical studies reveal that the thermally oxidized CP-Ti offers a better corrosion resistance than its untreated counterpart in both HCl and HNO3 mediums. The uniform surface coverage and compactness of the oxide layer provide an effective barrier toward corrosion of CP-Ti. The study concludes that thermal oxidation is an effective approach to engineer the surface of CP-Ti so as to increase its corrosion resistance in HCl and HNO3 mediums.

  3. In-situ laser ultrasonic measurement of the hcp to bcc transformation in commercially pure titanium

    SciTech Connect

    Shinbine, A. Garcin, T.; Sinclair, C.

    2016-07-15

    Using a novel in-situ laser ultrasonic technique, the evolution of longitudinal velocity was used to measure the α − β transformation during cyclic heating and cooling in commercially pure titanium. In order to quantify the transformation kinetics, it is shown that changes in texture can not be ignored. This is particularly important in the case of titanium where significant grain growth occurs in the β-phase leading to the ultrasonic wave sampling a decreasing number of grains on each thermal treatment cycle. Electron backscatter diffraction measurements made postmortem in the region where the ultrasonic pulse traveled were used to obtain an estimate of such local texture and grain size changes. An analysis technique for including the anisotropy of wave velocity depending on local texture is presented and shown to give self consistent results for the transformation kinetics. - Highlights: • Laser ultrasound and EBSD interpret the hcp/bcc phase transformation in cp-Ti. • Grain growth and texture produced variation in velocity during similar treatments. • Texture was deconvoluted from phase addition to obtain transformation kinetics.

  4. Amorphization effects on pure titanium using C{sup +}, O{sup +} and Cr{sup +} ion implantation

    SciTech Connect

    Athanasiou, N.S.; Lanza, F.; Paracchini, L.; Brossa, F.

    1998-01-20

    In this work, the influence of the amorphization effect of C{sup +}, O{sup +} and Cr{sup +} implantation on the friction and wettability properties of pure titanium (grade 2) has been studied. Doses from 1 {times} 10{sup 17} to 5 {times} 10{sup 17} ions cm{sup {minus}2} at multiple energies of 50 to 190 keV have been used. Additionally, pin-on-disk tribological tests using Ultra-High-Molecular-Weight-Polyethylene (UHMWPE) pins under lubricated conditions and wettability measurements of implanted and unimplanted titanium samples were carried out. The authors found, that the more suitable material for the wettability and hence wear resistance is C{sup +} implanted titanium, because of its higher surface energy than the unimplanted titanium corresponding energy. Friction tests on monoenergetic 180 keV C{sup +} and O{sup +} modified titanium with 1 {times} 10{sup 17} ions cm{sup {minus}2} have showed an essentially reduced friction compared to samples implanted with the same dose but at multiple energies. A reduction of the wettability by about 7% and the friction coefficient by about 18% was observed for carbon implanted titanium with a dose of 1 {times} 10{sup 17} C{sup +} cm{sup {minus}2}; this effect corresponds to a good correlation between wettability and friction coefficient after C{sup +} implantation in titanium. It was concluded that the reduction of the friction coefficient with monoenergetic C{sup +} implanted titanium is 3.7 times lower compared with those of pure titanium.

  5. [Effect of sintering gold paste coating on the bonding strength of pure titanium and three low-fusing porcelains].

    PubMed

    Zhang, Ya-li; Luo, Xiao-ping; Zhou, Li

    2012-05-01

    To study the effect of sintering gold paste coating of pure titanium on the adhesion of three porcelains following the protocol ISO 9693, and to investigate the titanium-porcelains interfaces. Sixty machined pure titanium samples were prepared in a rectangular shape according to ISO 9693 and divided equally into six groups. Half of the strips were coated with gold paste (Deckgold) and sintered. Three ultra-low-fusing dental porcelains (I: Initial Ti, S: Super porcelain Ti-22, T: TitanKeramik) were fused onto the titanium surfaces. A thin layer of bonding agent was only applied on the surfaces of uncoated gold specimens. The interface of the porcelain and titanium was observed with a field emission scanning electron microscope (FE-SEM) after metallographic preparation and sputtered with a very thin carbon layer of the embedded titanium-porcelain interface. After three-point bending test was performed, optical stereomicroscope was used to characterize the titanium-porcelains adhesion and determine the mode of failure. FE-SEM illustrated intermetallic compounds of Au-Ti formed with some visible microcracks in the gold layer and the interface of gold layer and ceramic. All the uncoated gold titanium-porcelain system showed predominately adhesive fracture at the titanium oxidation, whereas the failure modes in all gold coated systems were cohesive and adhesive, mainly cohesive. The three-point-bending test showed that the bonding strength of GS and GI groups [(37.08 ± 4.32) and (36.20 ± 2.40) MPa] were higher than those in uncoated groups [(31.56 ± 3.74) and (30.88 ± 2.60) MPa, P < 0.05], while no significant difference was found between T group and GT group (P > 0.05). The gold paste intermediate coatings can improve bond strengths of Super porcelain Ti-22 system and Initial Ti system, which have potential applications in clinical fields.

  6. Fatigue limits of titanium-bar joints made with the laser and the electric resistance welding techniques: microstructural characterization and hardness properties.

    PubMed

    Degidi, Marco; Nardi, Diego; Morri, Alessandro; Sighinolfi, Gianluca; Tebbel, Florian; Marchetti, Claudio

    2017-09-01

    Fatigue behavior of the titanium bars is of utmost importance for the safe and reliable operation of dental implants and prosthetic constructions based on these implants. To date, however, only few data are available on the fatigue strength of dental prostheses made with electric resistance welding and laser welding techniques. This in-vitro study highlighted that although the joints made with the laser welding approach are credited of a superior tensile strength, joints made with electric resistance welding exhibited double the minimum fatigue strength with respect to the joints made with laser welding (120 vs 60 N).

  7. Laser Powder Welding of a Ti52Al46.8Cr1Si0.2Titanium Aluminide Alloy at Elevated Temperature

    NASA Astrophysics Data System (ADS)

    Smal, C. A.; Meacock, C. G.; Rossouw, H. J.

    2011-04-01

    A method for the joining of a Ti52Al46.8Cr1Si0.2Titanium Aluminide alloy by laser powder welding is presented. The technique acts to join materials by consolidating powder with focused laser beam to form weld beads that fill a V joint. In order to avoid the occurrence of residual thermal stresses and hence cracking of the brittle material, the weld plates were heated to a temperature of 1173 K (= 900 °C) by an ohmic heating device, welded and then slowly cooled to produce pore and crack free welds.

  8. Welding.

    ERIC Educational Resources Information Center

    South Carolina State Dept. of Education, Columbia. Office of Vocational Education.

    This curriculum guide is designed for use by South Carolina vocational education teachers as a continuing set of lesson plans for a two-year course on welding. Covered in the individual sections of the guide are the following topics: an orientation to welding, oxyacetylene welding, advanced oxyacetylene welding, shielded metal arc welding, TIG…

  9. Welding.

    ERIC Educational Resources Information Center

    South Carolina State Dept. of Education, Columbia. Office of Vocational Education.

    This curriculum guide is designed for use by South Carolina vocational education teachers as a continuing set of lesson plans for a two-year course on welding. Covered in the individual sections of the guide are the following topics: an orientation to welding, oxyacetylene welding, advanced oxyacetylene welding, shielded metal arc welding, TIG…

  10. Evaluation of shear bond strength of porcelain bonded to laser welded titanium surface and determination of mode of bond failure.

    PubMed

    Patil, Narendra P; Dandekar, Minal; Nadiger, Ramesh K; Guttal, Satyabodh S

    2010-09-01

    The aim of this study was to evaluate the shear bond strength of porcelain to laser welded titanium surface and to determine the mode of bond failure through scanning electron microscopy (SEM) and energy dispersive spectrophotometry (EDS). Forty five cast rectangular titanium specimens with the dimension of 10 mm x 8 mm x 1 mm were tested. Thirty specimens had a perforation of 2 mm diameter in the centre. These were randomly divided into Group A and B. The perforations in the Group B specimens were repaired by laser welding using Cp Grade II titanium wire. The remaining 15 specimens were taken as control group. All the test specimens were layered with low fusing porcelain and tested for shear bond strength. The debonded specimens were subjected to SEM and EDS. Data were analysed with 1-way analysis of variance and Student's t-test for comparison among the different groups. One-way analysis of variance (ANOVA) showed no statistically significant difference in shear bond strength values at a 5% level of confidence. The mean shear bond strength values for control group, Group A and B was 8.4 +/- 0.5 Mpa, 8.1 +/- 0.4 Mpa and 8.3 +/- 0.3 Mpa respectively. SEM/EDS analysis of the specimens showed mixed and cohesive type of bond failure. Within the limitations of the study laser welding did not have any effect on the shear bond strength of porcelain bonded to titanium.

  11. Characterization of disk-laser dissimilar welding of titanium alloy Ti-6Al-4V to aluminum alloy 2024

    NASA Astrophysics Data System (ADS)

    Caiazzo, Fabrizia; Alfieri, Vittorio; Cardaropoli, Francesco; Corrado, Gaetano; Sergi, Vincenzo

    2013-02-01

    Both technical and economic reasons suggest to join dissimilar metals, benefiting from the specific properties of each material in order to perform flexible design. Adhesive bonding and mechanical joining have been traditionally used although adhesives fail to be effective in high-temperature environments and mechanical joining are not adequate for leak-tight joints. Friction stir welding is a valid alternative, even being difficult to perform for specific joint geometries and thin plates. The attention has therefore been shifted to laser welding. Interest has been shown in welding titanium to aluminum, especially in the aviation industry, in order to benefit from both corrosive resistance and strength properties of the former, and low weight and cost of the latter. Titanium alloy Ti-6Al-4V and aluminum alloy 2024 are considered in this work, being them among the most common ones in aerospace and automotive industries. Laser welding is thought to be particularly useful in reducing the heat affected zones and providing deep penetrative beads. Nevertheless, many challenges arise in welding dissimilar metals and the aim is further complicated considering the specific features of the alloys in exam, being them susceptible to oxidation on the upper surface and porosity formation in the fused zone. As many variables are involved, a systematic approach is used to perform the process and to characterize the beads referring to their shape and mechanical features, since a mixture of phases and structures is formed in the fused zone after recrystallization.

  12. Effect of zirconium addition on welding of aluminum grain refined by titanium plus boron

    NASA Astrophysics Data System (ADS)

    Zaid, A. I. O.

    2014-06-01

    Aluminum oxidizes freely in ordinary atmosphere which makes its welding difficult and weak, particularly it solidifies in columnar structure with large grains. Therefore, it is anticipated that the effect of addition of some grain refiners to its melt before solidification is worth while investigating as it may enhance its weldabilty and improve its mechanical strength. In this paper, the effect of addition of zirconium at a weight of 0.1% (which corresponds to the peretictic limit on the aluminum-zirconium base phase diagram) to commercially pure aluminum, grain refined by Ti+B on its weldability, using gas tungsten arc welding, GTAW, method which was formerly known as TIG. A constant current level of 30 AC Ampere was used because it removes the oxides during the welding process. Metallographic examination of the weldments of the different combinations of Al with Al and Al with its microalloys: in the heat affected zone, HAZ, and away from it was carried out and examined for HAZ width, porosity, cracks and microhardness. It was found that grain refining by Ti+B or Zr resulted in enhancement of the weldment.

  13. Surface modification of pure titanium by hydroxyapatite-containing composite coatings

    NASA Astrophysics Data System (ADS)

    Zhao, Quan-Ming; Cheng, Li; Yang, Hui-Lin; Liu, Zhong-Tang; Feng, De-Hong

    2014-12-01

    Micro-arc oxidation (MAO) is commonly applied to modify the surface of titanium (Ti)-based medical implants with a bioactive and porous Ti oxide (TiO2) coating. The study reports a new method of incorporating hydroxyapatite (HA) within the TiO2 coating by MAO and alkali heat treatment (AHT) in the solution containing Ca ion and P ion. The morphology, composition and phase composition of the coatings were analyzed with scanning electron microscopy with energy-dispersive X-ray spectrometer and X-ray diffraction. Surface topography and roughness of the coatings were investigated by atomic force microscopy operated in the tapping mode. The results showed that TiO2-based coatings were obtained on pure Ti by MAO with an electrolyte containing Ca ion and P ion; the prepared MAO coatings were mainly composed of Ca, P, O and Ti. AHT transformed Ca and P to HA crystals. In conclusion, the TiO2/HA composite coatings can be obtained on the surface of pure Ti by MAO and AHT, and the addition of Ca ion and P ion to the AHT solution contributed to the formation of HA.

  14. Corrosion behavior of titanium boride composite coating fabricated on commercially pure titanium in Ringer's solution for bioimplant applications.

    PubMed

    Sivakumar, Bose; Singh, Raghuvir; Pathak, Lokesh Chandra

    2015-03-01

    The boriding of commercially pure titanium was performed at 850°C, 910°C, and 1050°C for varied soaking periods (1, 3 and 5h) to enhance the surface properties desirable for bioimplant applications. The coating developed was characterized for the evolution of phases, microstructure and morphology, microhardness, and consequent corrosion behavior in the Ringer's solution. Formation of the TiB2 layer at the outermost surface followed by the TiB whiskers across the borided CpTi is unveiled. Total thickness of the composite layer on the substrates borided at 850, 910, and 1050°C for 5h was found to be 19.1, 26.4, and 18.2μm respectively which includes <3μm thick TiB2 layer. The presence of TiB2 phase was attributed to the high hardness ~2968Hv15gf of the composite coating. The anodic polarization studies in the simulated body fluid unveiled a reduction in the pitting corrosion resistance after boriding the CpTi specimens. However, this value is >0.55VSCE (electrochemical potential in in-vivo physiological environment) and hence remains within the safe region. Both the untreated and borided CpTi specimens show two passive zones associated with different passivation current densities. Among the CpTi borided at various times and temperatures, a 3h treated shows better corrosion resistance. The corrosion of borided CpTi occurred through the dissolution of TiB2. Copyright © 2014. Published by Elsevier B.V.

  15. Effect of Temperature Field on Formation of Friction Stir Welding Joints of Ti-6Al-4V Titanium Alloy

    NASA Astrophysics Data System (ADS)

    Yue, Yumei; Wen, Quan; Ji, Shude; Ma, Lin; Lv, Zan

    2017-07-01

    In order to investigate the formation mechanism of tunnel defect produced near the bottom of stir zone (SZ) in friction stir welding joint of Ti-6Al-4V titanium alloy, the temperature distribution during welding process was analyzed by numerical simulation and experiment. Results show that macrostructure morphology of SZ in cross section presents "bowl" shape owing to the characteristic of temperature distribution. Obvious temperature gradient appears along the thickness direction of joint. Decreasing rotational velocity reduces peak temperature and temperature gradient, which is beneficial to eliminate tunnel defect.

  16. In-line process control for laser welding of titanium by high dynamic range ratio pyrometry and plasma spectroscopy

    NASA Astrophysics Data System (ADS)

    Lempe, B.; Taudt, C.; Baselt, T.; Rudek, F.; Maschke, R.; Basan, F.; Hartmann, P.

    2014-02-01

    The production of complex titanium components for various industries using laser welding processes has received growing attention in recent years. It is important to know whether the result of the cohesive joint meets the quality requirements of standardization and ultimately the customer requirements. Erroneous weld seams can have fatal consequences especially in the field of car manufacturing and medicine technology. To meet these requirements, a real-time process control system has been developed which determines the welding quality through a locally resolved temperature profile. By analyzing the resulting weld plasma received data is used to verify the stability of the laser welding process. The determination of the temperature profile is done by the detection of the emitted electromagnetic radiation from the material in a range of 500 nm to 1100 nm. As detectors, special high dynamic range CMOS cameras are used. As the emissivity of titanium depends on the wavelength, the surface and the angle of radiation, measuring the temperature is a problem. To solve these a special pyrometer setting with two cameras is used. That enables the compensation of these effects by calculating the difference between the respective pixels on simultaneously recorded images. Two spectral regions with the same emissivity are detected. Therefore the degree of emission and surface effects are compensated and canceled out of the calculation. Using the spatially resolved temperature distribution the weld geometry can be determined and the laser process can be controlled. The active readjustment of parameters such as laser power, feed rate and inert gas injection increases the quality of the welding process and decreases the number of defective goods.

  17. Flexural strength of pure Ti, Ni-Cr and Co-Cr alloys submitted to Nd:YAG laser or TIG welding.

    PubMed

    Rocha, Rick; Pinheiro, Antônio Luiz Barbosa; Villaverde, Antonio Balbin

    2006-01-01

    Welding of metals and alloys is important to Dentistry for fabrication of dental prostheses. Several methods of soldering metals and alloys are currently used. The purpose of this study was to assess, using the flexural strength testing, the efficacy of two processes Nd:YAG laser and TIG (tungsten inert gas) for welding of pure Ti, Co-Cr and Ni-Cr alloys. Sixty cylindrical specimens were prepared (20 of each material), bisected and welded using different techniques. Four groups were formed (n=15). I: Nd:YAG laser welding; II- Nd:YAG laser welding using a filling material; III- TIG welding and IV (control): no welding (intact specimens). The specimens were tested in flexural strength and the results were analyzed statistically by one-way ANOVA. There was significant differences (p<0.001) among the non-welded materials, the Co-Cr alloy being the most resistant to deflection. Comparing the welding processes, significant differences (p<0.001) where found between TIG and laser welding and also between laser alone and laser plus filling material. In conclusion, TIG welding yielded higher flexural strength means than Nd:YAG laser welding for the tested Ti, Co-Cr and Ni-Cr alloys.

  18. Grain Size Effect of Commercial Pure Titanium Foils on Mechanical Properties, Fracture Behaviors and Constitutive Models

    NASA Astrophysics Data System (ADS)

    Daming, Nie; Zhen, Lu; Kaifeng, Zhang

    2017-02-01

    The constitutive models based on grain size effect are crucial for analyzing the deformation of metal foils. Previous investigations on the constitutive models concentrate on the foils whose thickness/average grain diameter (T/D) ratios are more than 3. In this study, the commercial pure titanium foils with thickness of 0.1 and 0.2 mm were employed as the experimental materials. The mechanical properties of foils with dimensions of nine different T/D ratios categorized into three ranges (T/D < 1, 1 ≤ T/D < 3, T/D ≥ 3)were tested. Meanwhile, the fracture behaviors and fracture mechanisms of the samples with different T/D ratios were compared and analyzed. Besides, three constitutive models incorporating the surface layer effect and grain boundary strengthening effect were established for the three T/D ratio ranges correspondingly. In these models, the thickness of the surface layers is set T for T/D < 1 foils, D for T/D > 3, and increases with D linearly in 1 ≤ T/D < 3. The results calculated by the three models were compared. The experiments indicate that those models are all in good agreement.

  19. Microstructure and Microtexture Evolution of Pure Titanium during Single Direction Torsion and Alternating Cyclic Torsion

    NASA Astrophysics Data System (ADS)

    Chen, Han; Li, Fuguo; Liu, Jie; Li, Jinghui; Ma, Xinkai; Wan, Qiong

    2017-05-01

    Systematic experimental studies of microstructure and crystallographic texture of pure titanium during the Single Direction Torsion (SDT) and Alternating Cyclic Torsion (ACT) are carried out at room temperature. The microstructure evolution indicates that the grain size can be refined during SDT, while the grain morphology can be controlled during ACT. Also, lots of {10-12} and few {11-22} twins are observed and their area percentages increase with increasing torsion angles during SDT. The microtexture evolution states that the deformation texture first approaches to the B fiber (0, 90, 0 to 60 deg), and then stays away from B fiber (0, 90, 0 to 60 deg) with increasing plastic strain during SDT. The change of deformation texture is mainly attributed to the appearance of {10-12} twin. However, the deformation texture is always close to B fiber (0, 90, 0 to 60 deg) during ACT. Finally, the effects of different dislocation movements caused by SDT and ACT are discussed. Quantities of subgrains with high density dislocation are observed during SDT while the {10-12} and {11-22} twins intersect with each other, and high density dislocations distribute the twin during ACT.

  20. Effect of Particle Morphology and Size Distribution on Cold-Sprayed Pure Titanium Coatings

    NASA Astrophysics Data System (ADS)

    Wong, W.; Vo, P.; Irissou, E.; Ryabinin, A. N.; Legoux, J.-G.; Yue, S.

    2013-10-01

    The effects of commercially pure titanium particle morphology (spherical, sponge, and irregular) and size distributions (mean particle sizes of 20-49 μm) on the cold spray process and resulting coating properties were investigated. Numerous powder and coating characterizations were performed including: powder oxygen and nitrogen contents, powder flowability, powder compressibility, coating microhardness, coating porosity, LOM/SEM analyses, and XRD. Compared to spherical powders, the sponge and irregular CP-Ti powders had higher oxygen content, poorer powder flowability, higher compression ratio, lower powder packing factor, and higher average particle impact velocities. XRD results showed no new phases present when comparing the various feedstock powders to corresponding coatings. A higher particle temperature was also obtained with larger particle size for all feedstock powder morphologies processed with the same set of spray parameters. A spherical powder with 29 μm mean particle size was found to have the lowest porosity coating and best cold sprayability. The relationships of several as-cold sprayed coating characteristics to the ratio of particle impact and critical velocities were also discussed.

  1. Microstructure and Microtexture Evolution of Pure Titanium during Single Direction Torsion and Alternating Cyclic Torsion

    NASA Astrophysics Data System (ADS)

    Chen, Han; Li, Fuguo; Liu, Jie; Li, Jinghui; Ma, Xinkai; Wan, Qiong

    2017-03-01

    Systematic experimental studies of microstructure and crystallographic texture of pure titanium during the Single Direction Torsion (SDT) and Alternating Cyclic Torsion (ACT) are carried out at room temperature. The microstructure evolution indicates that the grain size can be refined during SDT, while the grain morphology can be controlled during ACT. Also, lots of {10-12} and few {11-22} twins are observed and their area percentages increase with increasing torsion angles during SDT. The microtexture evolution states that the deformation texture first approaches to the B fiber (0, 90, 0 to 60 deg), and then stays away from B fiber (0, 90, 0 to 60 deg) with increasing plastic strain during SDT. The change of deformation texture is mainly attributed to the appearance of {10-12} twin. However, the deformation texture is always close to B fiber (0, 90, 0 to 60 deg) during ACT. Finally, the effects of different dislocation movements caused by SDT and ACT are discussed. Quantities of subgrains with high density dislocation are observed during SDT while the {10-12} and {11-22} twins intersect with each other, and high density dislocations distribute the twin during ACT.

  2. HISTOMORPHOMETRIC ANALYSIS OF PURE TITANIUM IMPLANTS WITH POROUS SURFACE VERSUS ROUGH SURFACE

    PubMed Central

    Brentel, Aline Scalone; de Vasconcellos, Luana Marotta Reis; Oliveira, Marize Varella; Graça, Mário Lima de Alencastro; de Vasconcellos, Luis Gustavo Oliveira; Cairo, Carlos Alberto Alves; Carvalho, Yasmin Rodarte

    2006-01-01

    The purpose of this study was to analyze the bone repair around commercially pure titanium implants with rough and porous surface, fabricated using powder metallurgy technique, after their insertion in tibiae of rabbits. Seven male rabbits were used. Each animal received 3 porous-surface implants in the left tibia and 3 rough-surface implants in the right tibia. The rabbits were sacrificed 4 weeks after surgery and fragments of the tibiae containing the implants were submitted to histological and histomorphometric analyses to evaluate new bone formation at the implant-bone interface. Means (%) of bone neoformation obtained in the histomorphometric analysis were compared by Student's t-test for paired samples at 5% significance level.. The results of the histological analysis showed that osseointegration occurred for both types of implants with similar quality of bone tissue. The histomorphometric analysis revealed means of new bone formation at implant-bone interface of 79.69 ± 1.00% and 65.05 ± 1.23% for the porous- and rough-surface implants, respectively. Statistically significant difference was observed between the two types of implants with respect to the amount new bone formation (p<0.05). In conclusion, the porous-surface implants contributed to the osseointegration because they provide a larger contact area at implant-bone interface. PMID:19089076

  3. Mechanical properties of cast commercially pure titanium simulating ceramic firing cycles.

    PubMed

    Fonseca, Johnson Campideli; Spazzin, Aloisio Oro; Naves, Lucas Zago; Costa, Ana Rosa; Correr-Sobrinho, Lourenco; Henriques, Guilhereme Elias Pessanha

    2012-07-01

    To evaluate the mechanical properties (ultimate tensile strength, elongation and hardness) of the commercially pure titanium (cp Ti) as casting and after ceramic firing cycles. Dumbbell-shaped specimens were prepared for the tensile strength testing. Disk-shaped cast specimens were used for microhardness testing. The ceramic firing cycles were made simulating a low fusion ceramic application. Tensile testing was conducted in a universal testing machine at a crosshead speed of 1 mm/min until failure. Ultimate tensile strength and elongation were recorded. The fracture mode was analyzed by scanning electron microscopy. Vickers hardness was measured in a hardness tester. The data from the tensile and hardness tests were subjected to a one-way analysis of variance and Tukey's test (α = 0.05). The mean values of tensile strength were not changed by the ceramic firing cycles. Lower hardness was observed for cp Ti as casting compared with Ti cast after the firing cycles. The ceramic firing cycles did not show any considerable prejudicial effects on the mechanical properties of the cp Ti.

  4. Fabrication of the Ti5Si3/Ti composite inoculants and its refining mechanism on pure titanium

    NASA Astrophysics Data System (ADS)

    Li, Nuo; Cui, Chunxiang; Liu, Shaungjin; Zhao, Long; Liu, Shuiqing

    2017-03-01

    The in situ Ti5Si3/Ti inoculants were successfully prepared by vacuum arc-melting and melt-spinning method. An efficient route by adding a small quantity of Ti5Si3/Ti inoculants to Ti melt has been first proposed to modify the coarse grains of as cast microstructure of pure titanium in this paper. It was found that the microstructure of ribbon inoculants was cellular structure that composed of Ti5Si3 and α-Ti phases. The grain refining effect of the inoculants was significantly improved with the adding ratio range from 0.2% to 0.5% in weight. With the increase of addition amount of inoculants on Ti melt, the tensile strength, yield strength and microhardness of pure titanium are significantly improved except elongation. The excellent grain refining effect can be attributed to the heterogeneous nucleation of the titanium grain on the precipitated Ti5Si3 phases in the Si-rich regions and the constitutional supercooling of Si in the Si-poverty regions. It is suggested that the in situ Ti5Si3/Ti inoculants is a promising inoculants for titanium alloys.

  5. [Influence of deposition time on chromatics during nitrogen-doped diamond like carbon coating on pure titanium].

    PubMed

    Yin, Lu; Yao, Jiang-wu; Xu, De-wen

    2010-10-01

    The aim of this study was to observed the influence of deposition time on chromatics during nitrogen-doped diamond like carbon coating (N-DLC) on pure titanium by multi impulse are plasma plating machine. Applying multi impulse are plasma plating machine to produce TiN coatings on pure titanium in nitrogen atmosphere, then filming with nitrogen-doped DLC on TiN in methane (10-80 min in every 5 min). The colors of N-DLC were evaluated in the CIE1976 L*a*b* uniform color scale and Mussell notation. The surface morphology of every specimen was analyzed using scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). When changing the time of N-DLC coating deposition, N-DLC surface showed different color. Golden yellow was presented when deposition time was 30 min. SEM showed that crystallization was found in N-DLC coatings, the structure changed from stable to clutter by varying the deposition time. The chromatics of N-DLC coatings on pure titanium could get golden yellow when deposition time was 30 min, then the crystallized structure was stable.

  6. Effect of temperature variation on the cytotoxicity of cast dental alloys and commercially pure titanium.

    PubMed

    Faria, Adriana Cláudia Lapria; Rodrigues, Renata Cristina Silveira; Antunes, Rossana Pereira de Almeida; de Mattos, Maria da Gloria Chiarello; Rosa, Adalberto Luiz; Ribeiro, Ricardo Faria

    2009-01-01

    Cell culture system has been used to evaluate alloy cytotoxicity under different environments, testing the extracts, but the effect of temperature variation on the cytotoxicity of dental alloys has not been analyzed. The aim of the present study was to investigate if temperature variation could affect dental alloy cytotoxicity, testing alloy extracts in an epithelial cell culture system. Discs of Ni-Cr, Co-Cr-Mo, Ni-Cr-Ti, Ti-6Al-4V and commercially pure titanium (cp Ti) were cast by arc melting, under argon atmosphere, injected by vacuum-pressure. Discs were immersed in artificial saliva and subjected to different temperatures: 37 degrees C and thermocycling (37 degrees C/5 degrees C/37 degrees C/55 degrees C/37 degrees C). After thermocycling, extracts were put in a subconfluent culture during 6 h, and the number of cells and their viability were used to evaluate cytotoxicity in these temperatures. For each alloy, data from temperature conditions were compared by Student's t-test (alpha=0.05). The cytotoxicity tests with alloy/metal extracts showed that Ni-Cr, Co-Cr-Mo, Ti-6Al-4V and cp Ti extracts (p>0.05) did not affect cell number or cell viability, while Ni-Cr-Ti (p<0.05) extract decreased cell number and viability when the alloy was subjected to thermocycling. Within the limitations of the present study, the Ni-Cr-Ti alloy had cell number and viability decreased when subjected to temperature variation, while the other alloys/metal extracts did not show these results.

  7. EFFECT OF TEMPERATURE VARIATION ON THE CYTOTOXICITY OF CAST DENTAL ALLOYS AND COMMERCIALLY PURE TITANIUM

    PubMed Central

    Faria, Adriana Cláudia Lapria; Rodrigues, Renata Cristina Silveira; Antunes, Rossana Pereira de Almeida; de Mattos, Maria da Gloria Chiarello; Rosa, Adalberto Luiz; Ribeiro, Ricardo Faria

    2009-01-01

    Cell culture system has been used to evaluate alloy cytotoxicity under different environments, testing the extracts, but the effect of temperature variation on the cytotoxicity of dental alloys has not been analyzed. Objective: The aim of the present study was to investigate if temperature variation could affect dental alloy cytotoxicity, testing alloy extracts in an epithelial cell culture system. Material and methods: Discs of Ni-Cr, Co-Cr-Mo, Ni-Cr-Ti, Ti-6Al-4V and commercially pure titanium (cp Ti) were cast by arc melting, under argon atmosphere, injected by vacuum-pressure. Discs were immersed in artificial saliva and subjected to different temperatures: 37°C and thermocycling (37°C/5°C/37°C/55°C/37°C). After thermocycling, extracts were put in a subconfluent culture during 6 h, and the number of cells and their viability were used to evaluate cytotoxicity in these temperatures. For each alloy, data from temperature conditions were compared by Student's t-test (α=0.05). Results: The cytotoxicity tests with alloy/metal extracts showed that Ni-Cr, Co-Cr-Mo, Ti-6Al-4V and cp Ti extracts (p>0.05) did not affect cell number or cell viability, while Ni-Cr-Ti (p<0.05) extract decreased cell number and viability when the alloy was subjected to thermocycling. Conclusion: Within the limitations of the present study, the Ni-Cr-Ti alloy had cell number and viability decreased when subjected to temperature variation, while the other alloys/metal extracts did not show these results. PMID:19936519

  8. Effects of Peracetic Acid on the Corrosion Resistance of Commercially Pure Titanium (grade 4).

    PubMed

    Raimundo, Lariça B; Orsi, Iara A; Kuri, Sebastião E; Rovere, Carlos Alberto D; Busquim, Thaís P; Borie, Eduardo

    2015-01-01

    The aim of this study was to evaluate the corrosion resistance of pure titanium grade 4 (cp-Ti-4), subjected to disinfection with 0.2% and 2% peracetic acid during different immersion periods using anodic potentiodynamic polarization test in acid and neutral artificial saliva. Cylindrical samples of cp-Ti-4 (5 mm x 5 mm) were used to fabricate 24 working electrodes, which were mechanically polished and divided into eight groups (n=3) for disinfection in 2% and 0.2% peracetic acid for 30 and 120 min. After disinfection, anodic polarization was performed in artificial saliva with pH 4.8 and 6.8 to assess the electrochemical behavior of the electrodes. A conventional electrochemical cell, constituting a reference electrode, a platinum counter electrode, and the working electrode (cp-Ti specimens) were used with a scanning rate of 1 mV/s. Three curves were obtained for each working electrode, and corrosion was characterized by using scanning electron microscopy (SEM) and energy dispersive x-ray spectrometry (EDS). Data of corrosion potential (Ecorr) and passive current (Ipass) obtained by the polarization curves were analyzed statistically by Student's t-test (a=0.05). The statistical analysis showed no significant differences (p>0.05) between artificial saliva types at different concentrations and periods of disinfection, as well as between control and experimental groups. No surface changes were observed in all groups evaluated. In conclusion, disinfection with 0.2% and 2% peracetic acid concentrations did not cause corrosion in samples manufactured with cp-Ti-4.

  9. High Power Laser Welding. [of stainless steel and titanium alloy structures

    NASA Technical Reports Server (NTRS)

    Banas, C. M.

    1972-01-01

    A review of recent developments in high power, carbon dixoide laser welding is presented. Deep penetration welding in stainless steel to 0.5-in. thick, high speed welding in thin gage rimmed steel and gas shielded welding in Ti-6Al-4V alloy are described. The effects of laser power, power density, focusing optics, gas-shielding techniques, material properties and weld speed on weld quality and penetration are discussed. It is shown that laser welding performance in thin materials is comparable to that of electron beams. It is further shown that high quality welds, as evidenced by NDT, mechanical and metal-lographic tests, can be achieved. The potential of the laser for industrial welding applications is indicated.

  10. Welding.

    ERIC Educational Resources Information Center

    Lehigh County Area Vocational-Technical School, Schnecksville, PA.

    This curriculum guide provides materials for a 12-unit secondary course in welding. Purpose stated for the flexible entry and exit course is to help students master manipulative skills to develop successful welding techniques and to gain an understanding of the specialized tools and equipment used in the welding field. Units cover oxyacetylene…

  11. Welding.

    ERIC Educational Resources Information Center

    Lehigh County Area Vocational-Technical School, Schnecksville, PA.

    This curriculum guide provides materials for a 12-unit secondary course in welding. Purpose stated for the flexible entry and exit course is to help students master manipulative skills to develop successful welding techniques and to gain an understanding of the specialized tools and equipment used in the welding field. Units cover oxyacetylene…

  12. Effect of Prior and Post-Weld Heat Treatment on Electron Beam Weldments of (α + β) Titanium alloy Ti-5Al-3Mo-1.5V

    NASA Astrophysics Data System (ADS)

    Anil Kumar, V.; Gupta, R. K.; Manwatkar, Sushant K.; Ramkumar, P.; Venkitakrishnan, P. V.

    2016-06-01

    Titanium alloy Ti5Al3Mo1.5V is used in the fabrication of critical engine components for space applications. Double vacuum arc re-melted and (α + β) forged blocks were sliced into 10-mm-thick plates and subjected to electron beam welding (EBW) with five different variants of prior and post-weld heat treatment conditions. Effects of various heat treatment conditions on the mechanical properties of the weldments have been studied. The welded coupons were characterized for microstructure, mechanical properties, and fracture analysis. An optimized heat treatment and welding sequence has been suggested. Weld efficiency of 90% could be achieved. Weldment has shown optimum properties in solution treated and aged condition. Heat-affected zone adjacent to weld fusion line is found to have lowest hardness in all conditions.

  13. Microstructure and Mechanical Properties of Pulsed Laser Beam Welded Ti-2Al-1.5Mn Titanium Alloy Joints

    NASA Astrophysics Data System (ADS)

    Fang, Xiuyang; Liu, Hong; Zhang, Jianxun

    2014-06-01

    The microstructure and mechanical properties in the pulsed laser beam welded joints of Ti-2Al-1.5Mn titanium alloy thin sheet were investigated in this study. The results show that the original α + β-phases and the transformed α + α'-phases are found in the partially transformed heat-affected zone (HAZ) together with the remaining β-phase, and the microhardness gradually enhances in the region as the result of the increase of α'-phase. The martensitic α'-phase and the remaining β-phase are detected in the fully transformed HAZ and the fusion zone (FZ), and the highest microhardness is found in these regions in virtue of the dominant α'-phase structure. The fine α'-phase appeared in the FZ results in higher average microhardness at high welding speed. Moreover, similar to the results of microhardness test, the tensile test results mean that the HAZ and FZ are stronger than the base metal (BM). Therefore, pulsed laser beam welding is feasible for joining thin sheet of Ti-2Al-1.5Mn titanium alloy.

  14. A comparative evaluation of laser and GTA welds in a high-strength titanium alloy -- Ti-6-22-22S

    SciTech Connect

    Baeslack, W.A. III; Hurley, J.; Paskell, T.

    1994-12-31

    Titanium alloy Ti-6Al-2Sn-2Zr-2Mo-2Cr-025Si (hereafter designated Ti-6-22-22S)is an alpha-beta titanium alloy developed for deep hardenability, high strength, intermediate temperature creep resistance, and moderate toughness. As a potential structural material for next-generation aircraft and aerospace systems, the weldability of Ti-6-22-22S has recently become a subject of increasing importance and concern. In the welding of titanium sheet, achieving satisfactory ductility is the principal limitation to alloy weldability, with poor ductility promoted by a coarse beta grain structure in the weld fusion and near-heat-affected zones. Square-butt welds were produced in 1.6 mm thick Ti-6-22-22S sheet using automatic GTA and CO{sub 2} laser welding systems. Microstructure analysis and DPH hardness traverses were performed on mounted. polished and etched specimens. Three-point bend and tensile tests were performed on transverse-weld and longitudinal-weld oriented specimens. Microstructure analysis of the laser welds revealed a fine, columnar fusion zone beta grain macrostructure and a fully-martensitic transformed-beta microstructure. Consistent with the microstructural similarities, fusion zone hardnesses of the laser welds were comparable (385 and 390 DPG, respectively) and greater than that of the base metal (330 DPH). In general, laser welds did not exhibit markedly superior ductilities relative to the GTAW, which was attributed to differences in the nature of the intragranular transformed-beta microstructures, being coarser and softer for the GTAW, the response of these as-welded microstructures to heat treatment, and interactions between the transformed-beta microstructure and the beta grain macrostructure.

  15. Corrosion behavior of pure titanium in the presence of Actinomyces naeslundii.

    PubMed

    Zhang, Song-Mei; Qiu, Jing; Tian, Fei; Guo, Xiao-Kui; Zhang, Fu-Qiang; Huang, Qing-Feng

    2013-05-01

    It is well known that some microorganisms affect the corrosion of dental metal. Oral bacteria such as Actinomyces naeslundii may alter the corrosion behavior and stability of titanium. In this study, the corrosion behavior of titanium was studied in a nutrient-rich medium both in the presence and the absence of A. naeslundii using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS). A. naeslundii was able to colonize the surface of titanium and then form a dense biofilm. The SEM images revealed the occurrence of micropitting corrosion on the metal surface after removal of the biofilm. The electrochemical corrosion results from EIS showed a significant decrease in the corrosion resistant (R(p)) value after immersing the metal in A. naeslundii culture for 3 days. Correspondingly, XPS revealed a reduction in the relative levels of titanium and oxygen and an obvious reduction of dominant titanium dioxide (TiO₂) in the surface oxides after immersion of the metal in A. naeslundii culture. These results suggest that the metabolites produced by A. naeslundii can weaken the integrity and stability of the protective TiO₂ in the surface oxides, which in turn decreases the corrosion resistance of titanium, resulting in increased corrosion of titanium immersed in A. naeslundii solution as a function of time.

  16. The Effect of Heat Treatment on the Microstructure and Properties of Explosively Welded Titanium-Steel Plates

    NASA Astrophysics Data System (ADS)

    Wachowski, Marcin; Gloc, Michał; Ślęzak, Tomasz; Płociński, Tomasz; Kurzydłowski, Krzysztof Jan

    2017-02-01

    This paper describes a study of explosively welded titanium-carbon steel S355J2+N plates. Following the welding, plates underwent heat treatment at temperature of 600 °C for 90 min with cooling in furnace to 300 °C and in air to room temperature. The structure of the bonding was examined by using light, scanning electron (SEM) and transmission electron microscopy. The mechanical properties before and after heat treatment were examined applying three-point bending tests with cyclic loads and hardness measurements. Fracture surfaces were investigated using computer tomography and SEM. It has been found that the bonding areas are characterized by a specific chemical composition, microstructure and microhardness. Between the steel and the Ti cladding, a strongly defected transition zone was formed and melted areas with altered chemical composition were observed. It was also demonstrated that the heat treatment commonly applied to welded steel-Ti plates had a significant and negative impact on the microstructure and mechanical properties of the welded plates due to formation of brittle intermetallic phases.

  17. The Effect of Heat Treatment on the Microstructure and Properties of Explosively Welded Titanium-Steel Plates

    NASA Astrophysics Data System (ADS)

    Wachowski, Marcin; Gloc, Michał; Ślęzak, Tomasz; Płociński, Tomasz; Kurzydłowski, Krzysztof Jan

    2017-03-01

    This paper describes a study of explosively welded titanium-carbon steel S355J2+N plates. Following the welding, plates underwent heat treatment at temperature of 600 °C for 90 min with cooling in furnace to 300 °C and in air to room temperature. The structure of the bonding was examined by using light, scanning electron (SEM) and transmission electron microscopy. The mechanical properties before and after heat treatment were examined applying three-point bending tests with cyclic loads and hardness measurements. Fracture surfaces were investigated using computer tomography and SEM. It has been found that the bonding areas are characterized by a specific chemical composition, microstructure and microhardness. Between the steel and the Ti cladding, a strongly defected transition zone was formed and melted areas with altered chemical composition were observed. It was also demonstrated that the heat treatment commonly applied to welded steel-Ti plates had a significant and negative impact on the microstructure and mechanical properties of the welded plates due to formation of brittle intermetallic phases.

  18. Comparison of single-beam and dual-beam laser welding of Ti-22Al-25Nb/TA15 dissimilar titanium alloys

    NASA Astrophysics Data System (ADS)

    Shen, Junqi; Li, Bo; Hu, Shengsun; Zhang, Hao; Bu, Xianzheng

    2017-08-01

    Laser beam welding (LBW) was used to join Ti-22Al-25Nb/TA15 dissimilar titanium alloys. The microstructure and mechanical properties of the welded joints under single and dual beam welding were analyzed and compared. In the mode of single laser beam, the fusion zone only consisted of B2 phase because of existence of β-phase stabilizer and rapid cooling rate of LBW. However, O phase was formed in the fusion zone while applying dual-beam laser welding due to decrease of the cooling rate. The microhardness distribution of the welded joint in dual-beam welding mode was consistent with that in single mode, but the hardness of the weld under dual laser beam was higher than that of single laser beam. In room-temperature tensile tests, the fractures all occurred in the weld, but the morphology exhibited a quasi-cleavage feature in single mode while the morphology was dimple fracture in the mode of dual laser beam. The tensile strength and elongation were both increased under dual-beam laser welding compared with those under single-beam laser welding.

  19. Simulation of the elastic deformation of laser-welded joints of an austenitic corrosion-resistant steel and a titanium alloy with an intermediate copper insert

    NASA Astrophysics Data System (ADS)

    Pugacheva, N. B.; Myasnikova, M. V.; Michurov, N. S.

    2016-02-01

    The macro- and microstructures and the distribution of elements and of the values of the microhardness and contact modulus of elasticity along the height and width of the weld metal and heat-affected zone of austenitic corrosion-resistant 12Kh18N10T steel (Russian analog of AISI 321) and titanium alloy VT1-0 (Grade 2) with an intermediate copper insert have been studied after laser welding under different conditions. The structural inhomogeneity of the joint obtained according to one of the regimes selected has been shown: the material of the welded joint represents a supersaturated solid solution of Fe, Ni, Cr, and Ti in the crystal lattice of copper with a uniformly distributed particles of intermetallic compounds Ti(Fe,Cr) and TiCu3. At the boundaries with steel and with the titanium alloy, diffusion zones with thicknesses of 0.1-0.2 mm are formed that represent supersaturated solid solutions based on iron and titanium. The strength of such a joint was 474 MPa, which corresponds to the level of strength of the titanium alloy. A numerical simulation of the mechanical behavior of welded joints upon the elastic tension-compression has been performed taking into account their structural state, which makes it possible to determine the amplitude values of the deformations of the material of the weld.

  20. Vacuum brazing of alumina ceramic to titanium for biomedical implants using pure gold as the filler metal

    NASA Astrophysics Data System (ADS)

    Siddiqui, Mohammad S.

    One of the many promising applications of metal/ceramic joining is in biomedical implantable devices. This work is focused on vacuum brazing of C.P titanium to 96% alumina ceramic using pure gold as the filler metal. A novel method of brazing is developed where resistance heating of C.P titanium is done inside a thermal evaporator using a Ta heating electrode. The design of electrode is optimized using Ansys resistive heating simulations. The materials chosen in this study are biocompatible and have prior history in implantable devices approved by FDA. This research is part of Boston Retinal implant project to make a biocompatible implantable device (www.bostonretina.org). Pure gold braze has been used in the construction of single terminal feedthrough in low density hermetic packages utilizing a single platinum pin brazed to an alumina or sapphire ceramic donut (brazed to a titanium case or ferrule for many years in implantable pacemakers. Pure gold (99.99%) brazing of 96% alumina ceramic with CP titanium has been performed and evaluated in this dissertation. Brazing has been done by using electrical resistance heating. The 96% alumina ceramic disk was manufactured by high temperature cofired ceramic (HTCC) processing while the Ti ferrule and gold performs were purchased from outside. Hermetic joints having leak rate of the order of 1.6 x 10-8 atm-cc/ sec on a helium leak detector were measured. Alumina ceramics made by HTCC processing were centreless grounded utilizing 800 grit diamond wheel to provide a smooth surface for sputtering of a thin film of Nb. Since pure alumina demonstrates no adhesion or wetting to gold, an adhesion layer must be used on the alumina surface. Niobium (Nb), Tantalum (Ta) and Tungsten (W) were chosen for evaluation since all are refractory (less dissolution into molten gold), all form stable oxides (necessary for adhesion to alumina) and all are readily thin film deposited as metals. Wetting studies are also performed to determine the

  1. Multifunctional commercially pure titanium for the improvement of bone integration: Multiscale topography, wettability, corrosion resistance and biological functionalization.

    PubMed

    Ferraris, Sara; Vitale, Alessandra; Bertone, Elisa; Guastella, Salvatore; Cassinelli, Clara; Pan, Jinshan; Spriano, Silvia

    2016-03-01

    The objects of this research are commercially pure titanium surfaces, with multifunctional behavior, obtained through a chemical treatment and biological functionalization. The explored surfaces are of interest for dental implants, in contact with bone, where several simultaneous and synergistic actions are needed, in order to get a fast and effective osseointegration. The here described modified surfaces present a layer of titanium oxide, thicker than the native one, with a multi-scale surface topography (a surface roughness on the nano scale, which can be overlapped to a micro or macro roughness of the substrate) and a high density of OH groups, that increase surface wettability, induce a bioactive behavior (hydroxyapatite precipitation in simulated body fluid) and make possible the grafting of biomolecules (alkaline phosphatase, ALP, in the present research). The surface oxide is an efficient barrier against corrosion, with passive behavior both with and without application of an external voltage. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. The long-term behaviors of passivation and hydride layer of commercial grade pure titanium in TRU waste disposal environments

    NASA Astrophysics Data System (ADS)

    Nakayama, Gen; Sakakibara, Yohei; Taniyama, Yoshihiro; Cho, Hideo; Jintoku, Takashi; Kawakami, Susumu; Takemoto, Mikio

    2008-09-01

    Preservation of the passivity under reducing environmental conditions for extended periods of time and the behavior of hydrogen evolution as the results of the preservation of the passivity of several candidate commercial grade pure titanium related to the small amount of palladium addition, such as Ti-Gr.17 for metallic containers to be buried under deep ground for disposing of transuranic (TRU) waste is investigated. The present investigation has revealed the following corrosion paths for the titanium alloys investigated. The passivity of the alloys is preserved as the result of repeated destruction and recovery of the surface films on the alloys. The long-term corrosion rate under the preserved passivity is of the order of 10 -6-10 -8 my -1 with evolution of hydrogen. The substrate alloys absorb parts of the hydrogen generated to form lath-type hydride phase before forming hydride layers at the final stage.

  3. Understanding the effects of process parameters on the properties of cold gas dynamic sprayed pure titanium coatings

    NASA Astrophysics Data System (ADS)

    Wong, Wilson

    The cold gas dynamic spraying of commercially pure titanium coatings was investigated. Specifically, the relationship between several key cold spray parameters on the quality of the resulting coatings was studied in order to gain a more thorough understanding of the cold spray process. To achieve this goal, three distinct investigations were performed. The first part of the investigation focussed on the effect of propelling gas, particularly helium and nitrogen, during the cold spraying of titanium coatings. Coatings were characterised by SEM and were evaluated for their deposition efficiency (DE), microhardness, and porosity. In selected conditions, three particle velocities were investigated such that for each condition, the propelling gasses temperature and pressure were attuned to attain similar particle velocities for each gas. In addition, a thick and fully dense cold sprayed titanium coating was achieved with optimised spray parameters and nozzle using helium. The corresponding average particle velocity was 1173 m/s. The second part of the investigation studied the effect of particle morphology (spherical, sponge, and irregular) and size distributions (mean particle sizes of 20, 29, and 36 mum) of commercially pure titanium on the mechanical properties of the resulting cold sprayed coatings. Numerous powder and coating characterisations were performed. From these data, semi-empirical flow (stress-strain) curves were generated based on the Johnson-Cook plasticity model which could be used as a measure of cold sprayability. Cold sprayability can be defined as the ease with which a powder can be cold sprayed. It was found that the sponge and irregular commercially pure titanium powders had higher oxygen content, poorer powder flowability, higher compression ratio, lower powder packing factor, and higher average particle impact velocities compared to the spherical powders. XRD results showed no new phases present when comparing the various feedstock powders to

  4. Effects of Long Term Thermal Exposure on Chemically Pure (CP) Titanium Grade 2 Room Temperature Tensile Properties and Microstructure

    NASA Technical Reports Server (NTRS)

    Ellis, David L.

    2007-01-01

    Room temperature tensile testing of Chemically Pure (CP) Titanium Grade 2 was conducted for as-received commercially produced sheet and following thermal exposure at 550 and 650 K for times up to 5,000 h. No significant changes in microstructure or failure mechanism were observed. A statistical analysis of the data was performed. Small statistical differences were found, but all properties were well above minimum values for CP Ti Grade 2 as defined by ASTM standards and likely would fall within normal variation of the material.

  5. Solid Particle Erosion Behaviors of Carbon-Fiber Epoxy Composite and Pure Titanium

    NASA Astrophysics Data System (ADS)

    Cai, Feng; Gao, Feng; Pant, Shashank; Huang, Xiao; Yang, Qi

    2016-01-01

    Rotor blades of Bell CH-146 Griffon helicopter experience excessive solid particle erosion at low altitudes in desert environment. The rotor blade is made of an advanced light-weight composite which, however, has a low resistance to solid particle erosion. Coatings have been developed and applied to protect the composite blade. However, due to the influence of coating process on composite material, the compatibility between coating and composite base, and the challenges of repairing damaged coatings as well as the inconsistency between the old and new coatings, replaceable thin metal shielding is an alternative approach; and titanium, due to its high-specific strength and better formability, is an ideal candidate. This work investigates solid particle erosion behaviors of carbon-fiber epoxy composite and titanium in order to assess the feasibility of titanium as a viable candidate for erosion shielding. Experiment results showed that carbon-fiber epoxy composite showed a brittle erosion behavior, whereas titanium showed a ductile erosion mode. The erosion rate on composite was 1.5 times of that on titanium at impingement angle 15° and increased to 5 times at impact angle 90°.

  6. Evaluation of the Pressing Characteristics of Commercially Pure Titanium Using an Instrumented Double Acting Die

    SciTech Connect

    Hovanski, Yuri; Lavender, Curt A.; Weil, K. Scott

    2008-06-19

    With recent advances in synthesizing titanium powder by low-cost routes, there has been growing interest in identifying process/material conditions that overcome the powder compaction problems typically found with this reactive metal. The use of instrumented dies in studying the cold pressing process for commercial iron and steel powders has provided greater insight into the complex phenomena that occur and may be used to evaluate constitutive relations that describe the compaction process. Nevertheless, little work has been conducted on the special, more problematic case of reactive metal powders such as titanium. An instrumented die was developed that allows die wall friction to be characterized and the radial stress distribution along the die wall and throughout the compact to be monitored. As will be presented, this tool has been used to investigate titanium compaction and to draw comparisons with results obtained on a baseline commercial iron powder. Both sets of data were systematically collected using various powder/die lubrication combinations.

  7. Friction Stir-Welded Titanium Alloy Ti-6Al-4V: Microstructure, Mechanical and Fracture Properties

    NASA Astrophysics Data System (ADS)

    Sanders, D. G.; Edwards, P.; Cantrell, A. M.; Gangwar, K.; Ramulu, M.

    2015-05-01

    Friction stir welding (FSW) has been refined to create butt welds from two sheets of Ti-6Al-4V alloy to have an ultra-fine grain size. Weld specimen testing was completed for three different FSW process conditions: As welded, stress relieved, stress relieved and machined, and for the un-welded base material. The investigation includes macrostructure, microstructure, microhardness, tensile property testing, notched bar impact testing, and fracture toughness evaluations. All experiments were conducted in accordance with industry standard testing specifications. The microstructure in the weld nugget was found to consist of refined and distorted grains of alpha in a matrix of transformed beta containing acicular alpha. The enhanced fracture toughness of the welds is a result of increased hardness, which is attributed to an increase in alpha phase, increase in transformed beta in acicular alpha, and grain refinement during the weld process. The noted general trend in mechanical properties from as welded, to stress relieved, to stress relieved and machined conditions exhibited a decrease in ultimate tensile strength, and yield strength with a small increase in ductility and a significant increase in fracture toughness.

  8. The influence of surface roughness and high pressure torsion on the growth of anodic titania nanotubes on pure titanium

    NASA Astrophysics Data System (ADS)

    Hu, Nan; Gao, Nong; Starink, Marco J.

    2016-11-01

    Anodic titanium dioxide nanotube (TNT) arrays have wide applications in photocatalytic, catalysis, electronics, solar cells and biomedical implants. When TNT coatings are combined with severe plastic deformation (SPD), metal processing techniques which efficiently improve the strength of metals, a new generation of biomedical implant is made possible with both improved bulk and surface properties. This work investigated the effect of processing by high pressure torsion (HPT) and different mechanical preparations on the substrate and subsequently on the morphology of TNT layers. HPT processing was applied to refine the grain size of commercially pure titanium samples and substantially improved their strength and hardness. Subsequent anodization at 30 V in 0.25 wt.% NH4F for 2 h to form TNT layers on sample surfaces prepared with different mechanical preparation methods was carried out. It appeared that the local roughness of the titanium surface on a microscopic level affected the TNT morphology more than the macroscopic surface roughness. For HPT-processed sample, the substrate has to be pre-treated by a mechanical preparation finer than 4000 grit for HPT to have a significant influence on TNTs. During the formation of TNT layers the oxide dissolution rate was increased for the ultrafine-grained microstructure formed due to HPT processing.

  9. Influence of oxidative nanopatterning and anodization on the fatigue resistance of commercially pure titanium and Ti-6Al-4V.

    PubMed

    Ketabchi, Amirhossein; Weck, Arnaud; Variola, Fabio

    2015-04-01

    With an increasingly aging population, a significant challenge in implantology is the creation of biomaterials that actively promote tissue integration and offer excellent mechanical properties. Engineered surfaces with micro- and nanoscale topographies have shown great potential to control and direct biomaterial-host tissue interactions. Two simple yet efficient chemical treatments, oxidative nanopatterning and anodization, have demonstrated the ability to confer exciting new bioactive capacities to commercially pure titanium and Ti-6Al-4V alloy. However, the resulting nanoporous and nanotubular surfaces require careful assessment in regard to potential adverse effects on the fatigue resistance, a factor which may ultimately cause premature failure of biomedical implants. In this work, we have investigated the impact of oxidative nanopatterning and anodization on the fatigue resistance of commercially pure titanium and Ti-6Al-4V. Quantitative (e.g., S-N curves) and qualitative analyses were carried out to precisely characterize the fatigue response of treated metals and compare it to that of polished controls. Scanning electron microscopy (SEM) imaging revealed the effects of cyclic loading on the fracture surface and on the structural integrity of chemically grown nanostructured oxides. Results from this study reinforce the importance of mechanical considerations in the development and optimization of micro- and nanoscale surface treatments for metallic biomedical implants.

  10. The influence of commercially pure titanium and titanium-aluminum-vanadium alloy on the final shade of low-fusing porcelain.

    PubMed

    Al Wazzan, Khalid A; Al Hussaini, Ibrahim S

    2007-02-01

    The aims of this study were to investigate the influence of commercially pure titanium (PTi) and titanium-aluminum-vanadium (Ti-6Al-4V) alloys (TiA) on the final shade of low-fusing porcelain bonded to them and to compare the shade changes with those of three conventional metal-ceramic systems. A titanium casting unit was used to cast PTi and Ti-6Al-4V alloy specimens followed by A3 shade low-fusing porcelain (Noritake) being bonded to them. Gold-based (AuA), palladium-based (PdA), and nickel-chromium (Ni-Cr) alloys were cast with an automatic centrifugal casting machine, then A3 shade conventional porcelain material (Vita, VMK 95) was applied to them. Ten specimens of each metal were then fabricated. The CIE L* a* b* color coordinates of the specimens were measured with a spectrophotometer. All alloys had significant color changes when compared with A3 shade tabs. The color differences from the shade tabs were 5.79 for the Ti-6Al-4V group, 6.46 for PdA alloy, 8.12 for AuA alloy, 8.15 for Ni-Cr alloy, and 12.58 for PTi. The specimens differed from the shade tabs primarily because of the differences in a* and b* coordinate values. Predictable shade reproduction of metal-ceramic restorations (MCRs) may be impaired by the underlying metal. The PTi had the greatest color differences among all the tested metal when compared with the shade tabs, whereas the Ti-6Al-4V alloy had the lowest. PTi is more likely to affect the final shade of low-fusing porcelain than Ti-6Al-4V alloy.

  11. Effect of a copper filler metal on the microstructure and mechanical properties of electron beam welded titanium-stainless steel joint

    SciTech Connect

    Wang, Ting; Zhang, Binggang; Feng, Jicai; Tang, Qi

    2012-11-15

    Cracking in an electron beam weld of titanium to stainless steel occurred during the cooling process because of internal thermal stress. Using a copper filler metal, a crack free joint was obtained, which had a tensile strength of 310 MPa. To determine the reasons for cracking in the Ti/Fe joint and the function of the copper filler metal on the improvement of the cracking resistance of the Ti/Cu/Fe joint, the microstructures of the joints were studied by optical microscopy, scanning electron microscopy and X-ray diffraction. The cracking susceptibilities of the joints were evaluated with microhardness tests on the cross-sections. In addition, microindentation tests were used to compare the brittleness of the intermetallics in the welds. The results showed that the Ti/Fe joint was characterized by continuously distributed brittle intermetallics such as TiFe and TiFe(Cr){sub 2} with high hardness ({approx} 1200 HV). For the Ti/Cu/Fe joint, most of the weld consisted of a soft solid solution of copper with dispersed TiFe intermetallics. The transition region between the weld and the titanium alloy was made up of a relatively soft Ti-Cu intermetallic layer with a lower hardness ({approx} 500 HV). The formation of soft phases reduced the cracking susceptibility of the joint. - Highlights: Black-Right-Pointing-Pointer Electron beam welded Ti/Fe joint cracked for the brittleness and residual stress. Black-Right-Pointing-Pointer Electron beam welded Ti/Cu/Fe joint with tensile strength of 310 MPa was obtained. Black-Right-Pointing-Pointer Cu diluted Ti and Fe contents in weld and separated the TiFe{sub 2} into individual blocks. Black-Right-Pointing-Pointer Interfacial hard Ti-Fe compounds were replaced by soft Ti-Cu compounds in the weld. Black-Right-Pointing-Pointer A large amount of solid solution of copper formed in the weld.

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

    PubMed

    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.

  13. Histomorphological and Histomorphometric Analyses of Grade IV Commercially Pure Titanium and Grade V Ti-6Al-4V Titanium Alloy Implant Substrates: An In Vivo Study in Dogs.

    PubMed

    Ribeiro da Silva, Jonathan; Castellano, Arthur; Malta Barbosa, João Pedro; Gil, Luiz F; Marin, Charles; Granato, Rodrigo; Bonfante, Estevam A; Tovar, Nick; Janal, Malvin N; Coelho, Paulo G

    2016-10-01

    To evaluate the bone response to grade IV commercially pure titanium (G4) relative to Ti-6Al-4V (G5). Implant surface topography was characterized by optical interferometry and scanning electron microscopy (SEM). Thirty-six implants (Signo Vinces, n = 18 per group) were installed in the radius of 18 dogs. The animals were killed at 1, 3, and 6 weeks, resulting in 6 implants per group and time in vivo for bone morphology, bone-to-implant contact (BIC), and bone area fraction occupancy (BAFO) evaluation. SEM depicted a more uniform topography of G4 than G5. Surfaces were statistically homogeneous for Sa, Sq, and Sdr. At 1 week, new bone formation was observed within the healing connective tissue in contact with the implant surface. At 3 weeks, new bone in direct contact with the implant surface was observed at all bone regions. At 6 weeks, the healing chambers filled with woven bone depicted an onset of replacement by lamellar bone. No significant effect of substrate was detected. Time presented an effect on BIC and BAFO (P < 0.001). Both titanium substrates were biocompatible and osseoconductive at the bone tissue level.

  14. Titanium

    SciTech Connect

    Fox, G.J.

    1997-01-01

    The article contains a summary of factors pertinent to titanium use. Geology and exploitation, production processes, global production, titanium dioxide and alloy applications, and the titanium market are reviewed. Potential applications outlined are for oil and gas equipment and for the automotive industry. Titanium alloys were selected for drilling risers for North Sea oil and gas drilling platforms due to a high strength-to-weight ratio and corrosion resistance. These properties also make titanium alloys attractive for auto parts, although the cost is currently prohibitive.

  15. Formation of mixed and patterned self-assembled films of alkylphosphonates on commercially pure titanium surfaces

    NASA Astrophysics Data System (ADS)

    Rudzka, Katarzyna; Sanchez Treviño, Alda Y.; Rodríguez-Valverde, Miguel A.; Cabrerizo-Vílchez, Miguel A.

    2016-12-01

    Titanium is extensively employed in biomedical devices, in particular as implant. The self-assembly of alkylphosphonates on titanium surfaces enable the specific adsorption of biomolecules to adapt the implant response against external stimuli. In this work, chemically-tailored cpTi surfaces were prepared by self-assembly of alkylphosphonate molecules. By bringing together attributes of two grafting molecules, aqueous mixtures of two alkylphosphonates were used to obtain mixed self-assembled films. Single self-assembled films were also altered by laser abrasion to produce chemically patterned cpTi surfaces. Both mixed and patterned self-assembled films were confirmed by AFM, ESEM and X-ray photoelectron spectroscopy. Water contact angle measurements also revealed the composition of the self-assembly films. Chemical functionalization with two grafting phosphonate molecules and laser surface engineering may be combined to guide the bone-like formation on cpTi, and the future biological response in the host.

  16. Hardening of the surface layers of commercial pure titanium VT1-0 under combined treatment

    SciTech Connect

    Bashchenko, Lyudmila P. Gromov, Viktor E. Budovskikh, Evgenii A. Soskova, Nina A.; Ivanov, Yurii F.

    2015-10-27

    The treatment of VT1-0 titanium samples was carried out by concentrated energy fluxes. The combined treatment included surface carburizing with the joint use of powder samples of compounds with high physical and mechanical properties (namely, titanium diboride TiB{sub 2}, silicon carbide SiC and zirconium oxide ZrO{sub 2}) and subsequent electron beam treatment of surface layers formed in electroexplosive treatment. The combined treatment of surface layers resulted in the multifold increase in microhardness, which reduces depending on the depth of hardening zone. After electron-beam treatment, the depth of hardening zone is increased. During electron-beam treatment, the two-layer hardening zone forms.

  17. Hardening of the surface layers of commercial pure titanium VT1-0 under combined treatment

    NASA Astrophysics Data System (ADS)

    Bashchenko, Lyudmila P.; Gromov, Viktor E.; Budovskikh, Evgenii A.; Ivanov, Yurii F.; Soskova, Nina A.

    2015-10-01

    The treatment of VT1-0 titanium samples was carried out by concentrated energy fluxes. The combined treatment included surface carburizing with the joint use of powder samples of compounds with high physical and mechanical properties (namely, titanium diboride TiB2, silicon carbide SiC and zirconium oxide ZrO2) and subsequent electron beam treatment of surface layers formed in electroexplosive treatment. The combined treatment of surface layers resulted in the multifold increase in microhardness, which reduces depending on the depth of hardening zone. After electron-beam treatment, the depth of hardening zone is increased. During electron-beam treatment, the two-layer hardening zone forms.

  18. Electrochemical Behavior Assessment of Micro- and Nano-Grained Commercial Pure Titanium in H2SO4 Solutions

    NASA Astrophysics Data System (ADS)

    Fattah-alhosseini, Arash; Ansari, Ali Reza; Mazaheri, Yousef; Karimi, Mohsen

    2017-02-01

    In this study, the electrochemical behavior of commercial pure titanium with both coarse-grained (annealed sample with the average grain size of about 45 µm) and nano-grained microstructure was compared by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott-Schottky analysis. Nano-grained Ti, which typically has a grain size of about 90 nm, is successfully made by six-cycle accumulative roll-bonding process at room temperature. Potentiodynamic polarization plots and impedance measurements revealed that as a result of grain refinement, the passive behavior of the nano-grained sample was improved compared to that of annealed pure Ti in H2SO4 solutions. Mott-Schottky analysis indicated that the passive films behaved as n-type semiconductors in H2SO4 solutions and grain refinement did not change the semiconductor type of passive films. Also, Mott-Schottky analysis showed that the donor densities decreased as the grain size of the samples reduced. Finally, all electrochemical tests showed that the electrochemical behavior of the nano-grained sample was improved compared to that of annealed pure Ti, mainly due to the formation of thicker and less defective oxide film.

  19. Effect of surface contamination on adhesive bonding of cast pure titanium and Ti-6Al-4V alloy.

    PubMed

    Watanabe, I; Watanabe, E; Yoshida, K; Okabe, T

    1999-03-01

    There is little information regarding bond strengths of resin cements to cast titanium surfaces contaminated by investment material. This study examined the effect of surface contamination on the shear bond strength of resin cements to cast titanium and Ti-6Al-4V alloy. Two types of disks were cast from commercially pure titanium (CP-Ti) and Ti-6Al-4V alloy ingots using an argon-arc pressure casting unit and a phosphate-bonded Al2 O3 /LiAlSiO6 investment. After casting, disks were subjected to 3 surface treatments: (1) cast surface sandblasted (50 microm-sized Al2 O3 ) for 30 seconds; (2) metal surface sanded with silicon-carbide paper (600 grit) after grinding the contaminated cast surface (approximately 200 microm in thickness); and (3) metal surface sandblasted for 30 seconds after treatment 2. Surface structures were examined after each treatment with SEM and optical microscopy. Each type of disk was then bonded with 2 types of luting materials. Bonded specimens were subjected to thermocycling for up to 50,000 cycles, and shear bond strengths were determined after 0 (baseline) and 50,000 thermocycles. Results were statistically analyzed with 3-way ANOVA (P <.05). Microscopic observation of cast CP-Ti and Ti-6Al-4V exhibited noticeable structures on the cast surfaces apparently contaminated with investment material. However, there were no statistical differences (P >.05) in the bond strengths of both cements between contaminated (treatment 1) and uncontaminated surfaces (treatment 3) for both metals at baseline and after 50,000 thermocycles. The bond strength of specimens sanded with silicon-carbide paper (treatment 2) deteriorated dramatically after 50,000 thermocycles. Contamination of the cast metal surfaces by elements of the investment during casting did not affect bond strengths of the luting materials to CP-Ti and Ti-6Al-4V.

  20. The role of titanium in the non-metallic inclusions which nucleate acicular ferrite in the submerged arc weld (SAW) fusion zones of Navy HY-100 steel

    SciTech Connect

    Fox, A.G.; Brothers, D.G.

    1995-04-01

    The origin of acicular ferrite in the weld metal of submerged arc weldments on high strength steels is very complex and depends upon the chemical composition for the steel base plate and filler wire, the composition of the flux used during welding and the cooling rate of the weld metal during the transformation of the undercooled metastable austenite. The strength and toughness of weld metal improves as the amount of acicular ferrite increases due its fine basket weave microstructure and so it is important to understand the mechanism of its formation so that the volume fraction of acicular ferrite can be maximized in steel weld metal. The chemical composition of the filler wire mostly determines the final composition of the weld metal although the composition of the base plate is important because of dilution effects. In high strength steels the alloying elements such as carbon, nickel, chromium, copper nd niobium are present to achieve the required strength levels and a fortuitous outcome of this is a continuous cooling transformation (CCT) diagram with features that mean that bainite is the major transformation product during the arc welding of these steels provided a suitable weld power and preheat/interpass temperature is chosen during multi-run welding. Once a suitable weld-metal hardenability and cooling rate has been established the amount of acicular ferrite nucleated will depend on the size, number, distribution and chemical composition of the non-metallic inclusions. Suitable inclusions appear to be in the size range 0.2--2.0 micrometers with a mean size of 0.5 micrometers being about an optimum value. These inclusions usually contain manganese, silicon, aluminum and titanium as their major constituents and do not appear to be exactly spherical but have a faceted or slightly angular appearance.

  1. Experimental study on the behavior of primary human osteoblasts on laser-cused pure titanium surfaces.

    PubMed

    Markwardt, Jutta; Friedrichs, Jens; Werner, Carsten; Davids, Andreas; Weise, Hartmut; Lesche, Raoul; Weber, Anke; Range, Ursula; Meißner, Heike; Lauer, Günther; Reitemeier, Bernd

    2014-05-01

    Mandibular tumor resection can lead to a mandibular segmental defect. LaserCUSING® is used to produce a mandibular implant, designed to be identical to the shape of the mandibular defect. Novel microrough surfaces result from this generative technology. In the current study, the behavior of human osteoblasts on untreated laser-cused titanium specimens or on specimens conditioned with different blasting agents was analyzed. The conditioning of these specimens resulted in surfaces with graded roughness. White light confocal microscopy and single-cell force spectroscopy were used to characterize the surface of the specimens and to quantify the initial adhesion of primary human osteoblasts to the specimens, respectively. Furthermore, cell growth, viability, apoptosis as well as mineralization of the specimens were analyzed over a time-period of 2 months. Compared to specimens that were treated with blasting agents, untreated specimens had the highest surface roughness. Quantitative SCFS measurements demonstrated that the adhesion of human primary osteoblasts was the highest on these specimens. Additionally, the untreated specimens allowed the highest number of osteoblasts to colonize. Mineralization studies showed increasing calcium and phosphor elemental composition for all specimen series. It can be concluded that untreated laser-cused titanium specimens are superior to promote the initial adhesion and subsequent colonization by osteoblast cells.

  2. Effects of Long-Term Thermal Exposure on Commercially Pure Titanium Grade 2 Elevated-Temperature Tensile Properties

    NASA Technical Reports Server (NTRS)

    Ellis, David L.

    2012-01-01

    Elevated-temperature tensile testing of commercially pure titanium (CP Ti) Grade 2 was conducted for as-received commercially produced sheet and following thermal exposure at 550 and 650 K (531 and 711 F) for times up to 5000 h. The tensile testing revealed some statistical differences between the 11 thermal treatments, but most thermal treatments were statistically equivalent. Previous data from room temperature tensile testing was combined with the new data to allow regression and development of mathematical models relating tensile properties to temperature and thermal exposure. The results indicate that thermal exposure temperature has a very small effect, whereas the thermal exposure duration has no statistically significant effects on the tensile properties. These results indicate that CP Ti Grade 2 will be thermally stable and suitable for long-duration space missions.

  3. Imaging of Compressed Pure-CH Shells and CH Shells with Titanium-Doped Layers on OMEGA

    NASA Astrophysics Data System (ADS)

    Smalyuk, V. A.; Yaakobi, B.; Goncharov, V. N.; Delettrez, J. A.; Marshall, F. J.; Meyerhofer, D. D.

    1999-11-01

    The compressed shell integrity of spherical targets has been studied using the 60-beam, 30-kJ UV, OMEGA laser system. The emission from the hot core has been imaged through the cold shell at two narrow, x-ray energy bands, absorbing and nonabsorbing by the shell, allowing nonuniformities in the core emission and the cold shell areal density to be measured. Images of the target have been obtained using a pinhole-array with K-edge filters. The x-ray energies used are around 2.8 and 4.5 keV for pure-CH shells, and around 4.5 and 6 keV for titanium-doped layers. Additional images of the shell are obtained with a framed monochromatic x-ray microscope and a time-integrated crystal-spectrometer/pinhole-array combination. We will present measurements of the compressed shell integrity at the stagnation stage of spherical implosions by varying the position of the titanium-doped layer within the shell, by varying the thickness of the CH shell, and by using two different laser pulse shapes. The experimental results will be compared with 2-D (ORCHID) hydrodynamic simulations. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460, the University of Rochester, and the New York State Energy Research and Development Authority.

  4. Microstructure and Mechanical Properties of Laser-Welded Joints of Ti-22Al-25Nb/TA15 Dissimilar Titanium Alloys

    NASA Astrophysics Data System (ADS)

    Li, Dalong; Hu, Shengsun; Shen, Junqi; Zhang, Hao; Bu, Xianzheng

    2016-05-01

    Laser beam welding (LBW) was applied to join 1-mm-thick dissimilar titanium alloys, Ti-22Al-25Nb (at.%) and TA15, and the microstructure and mechanical properties of the welded joints were systematically analyzed. Defect-free joints were obtained, and the fusion zone mainly consisted of B2 and martensitic α' phases because of the uneven distribution of the β phase stabilizer and rapid cooling rate of LBW. The phase compositions of the heat-affected zone varied with the different thermal cycles during the welding process. The different microstructures of the dissimilar titanium alloys led to an unsymmetrical hardness profile, with the welded seam exhibiting the lowest value of 271 HV. In room-temperature tensile tests, the fractures all occurred preferentially in the fusion zone. The strengths of the joints were close to those of the base metal but with prominently decreasing ductility. In tensile tests performed at 550 °C, all the joints fractured in the TA15 base metal, and the strength and plasticity of the welds were equivalent to those of the TA15 base metal.

  5. Diffusion bonding of commercially pure titanium to low carbon steel using a silver interlayer

    SciTech Connect

    Atasoy, Evren; Kahraman, Nizamettin

    2008-10-15

    Titanium and low carbon steel plates were joined through diffusion bonding using a silver interlayer at various temperatures for various diffusion times. In order to determine the strength of the resulting joints, tensile-shear tests and hardness tests were applied. Additionally, optical, scanning electron microscopy examinations and energy dispersive spectrometry elemental analyses were carried out to determine the interface properties of the joint. The work showed that the highest interface strength was obtained for the specimens joined at 850 deg. C for 90 min. It was seen from the hardness results that the highest hardness value was obtained for the interlayer material and the hardness values on the both sides of the interlayer decreased gradually as the distance from the joint increased. In energy dispersive spectrometry analyses, it was seen that the amount of silver in the interlayer decreased markedly depending on the temperature rise. In addition, increasing diffusion time also caused some slight decrease in the amount of silver.

  6. Welding.

    ERIC Educational Resources Information Center

    Cowan, Earl; And Others

    The curriculum guide for welding instruction contains 16 units presented in six sections. Each unit is divided into the following areas, each of which is color coded: terminal objectives, specific objectives, suggested activities, and instructional materials; information sheet; transparency masters; assignment sheet; test; and test answers. The…

  7. Welding.

    ERIC Educational Resources Information Center

    Baldwin, Harold; Whitney, Gregory

    This curriculum guide is intended to assist vocational instructors in preparing students for entry-level employment as welders and preparing them for advanced training in the workplace. The package contains an overview of new and emerging welding technologies, a competency/skill and task list, an instructor's guide, and an annotated bibliography.…

  8. Welding.

    ERIC Educational Resources Information Center

    Baldwin, Harold; Whitney, Gregory

    This curriculum guide is intended to assist vocational instructors in preparing students for entry-level employment as welders and preparing them for advanced training in the workplace. The package contains an overview of new and emerging welding technologies, a competency/skill and task list, an instructor's guide, and an annotated bibliography.…

  9. Full-Field Strain Behavior of Friction Stir-Welded Titanium Alloy

    DTIC Science & Technology

    2008-01-01

    microstructural uniformity and mechanical properties [2]. Typical FSW tools for aluminum are made from tool steel and can have fairly elaborate geometries...2]. Much has been accomplished in characterizing FSW joints in 2XXX and 7XXX series aluminum alloys for aerospace use, but little published...roughly two thirds higher than aluminum . The tensile stiffness of titanium sheet is between that of steel and aluminum , but titanium’s strength

  10. Enhanced osteoblast proliferation and corrosion resistance of commercially pure titanium through surface nanostructuring by ultrasonic shot peening and stress relieving.

    PubMed

    Jindal, Shitu; Bansal, Rajesh; Singh, Bijay P; Pandey, Rajiv; Narayanan, Shankar; Wani, Mohan R; Singh, Vakil

    2014-07-01

    This investigation was carried out to study the effect of a novel process of surface modification, surface nanostructuring by ultrasonic shot peening, on osteoblast proliferation and corrosion behavior of commercially pure titanium (c p-Ti) in simulated body fluid. A mechanically polished disc of c p-Ti was subjected to ultrasonic shot peening with stainless steel balls to create nanostructure at the surface. A nanostructure (<20 nm) with inhomogeneous distribution was revealed by atomic force and scanning electron microscopy. There was an increase of approximately 10% in cell proliferation, but there was drastic fall in corrosion resistance. Corrosion rate was increased by 327% in the shot peened condition. In order to examine the role of residual stresses associated with the shot peened surface on these aspects, a part of the shot peened specimen was annealed at 400°C for 1 hour. A marked influence of annealing treatment was observed on surface structure, cell proliferation, and corrosion resistance. Surface nanostructure was much more prominent, with increased number density and sharper grain boundaries; cell proliferation was enhanced to approximately 50% and corrosion rate was reduced by 86.2% and 41% as compared with that of the shot peened and the as received conditions, respectively. The highly significant improvement in cell proliferation, resulting from annealing of the shot peened specimen, was attributed to increased volume fraction of stabilized nanostructure, stress recovery, and crystallization of the oxide film. Increase in corrosion resistance from annealing of shot peened material was related to more effective passivation. Thus, the surface of c p-Ti, modified by this novel process, possessed a unique quality of enhancing cell proliferation as well as the corrosion resistance and could be highly effective in reducing treatment time of patients adopting dental and orthopedic implants of titanium and its alloys.

  11. Strain measurement of pure titanium covered with soft tissue using X-ray diffraction.

    PubMed

    Fujisaki, Kazuhiro; Tadano, Shigeru

    2010-03-01

    Measurement of the stress and strain applied to implants and bone tissue in the human body are important for fracture prediction and evaluations of implant adaptation. The strain of titanium (Ti) materials can be measuring by X-ray diffraction techniques. This study applied X-ray diffraction to the skin tissue-covered Ti. Characteristic X-rays of Mo Kalpha were used and the X-rays diffracted from the Ti were detected through the covering skin tissue. The X-ray absorption by skin tissue is large under the diffracted X-rays detected in low angles because the length of penetration depends on the angle of inclination, equal to the Bragg angle. The effects of skin tissue to detect the diffracted X-rays were investigated in the experiments. And the strain measurements were conducted under bending loads applied to the Ti specimen. The effect of skin tissue was absorption of X-rays as well as the X-rays scattered from the physiological saline contained in the tissue. The X-rays scattered by the physiological saline creates a specific background pattern near the peaks from the (002) and (011) lattice planes of Ti in the X-ray diffraction profile. Diffracted X-rays from the Ti were detected after being transmitted through 1 mm thick skin tissue by Mo Kalpha. Individual peaks such as (010), (002), (011), and (110) were clearly established by using a parallel beam arrangement. The strains of (110) lattice planes were measured with or without the tissue cover were very similar. The strain of the (110) lattice planes of Ti could be measured by Mo Kalpha when the Ti specimen was located under the skin tissue.

  12. Surface roughness and fatigue performance of commercially pure titanium and Ti-6Al-4V alloy after different polishing protocols.

    PubMed

    Guilherme, Aderico Santana; Henriques, Guilherme Elias Pessanha; Zavanelli, Ricardo Alexandre; Mesquita, Marcelo Ferraz

    2005-04-01

    Surface quality of cast metal is directly related to service performance under fatigue stress. Surface heterogeneities resulting from either finishing or polishing processes or by corrosive agents such as fluoridated solutions, can negatively affect fatigue life. Cast titanium frameworks are difficult to polish, and an accepted polishing protocol has not been established. This study evaluated and compared surface roughness of cast commercially pure titanium (CP Ti) and Ti-6Al-4V alloy submitted to conventional or electrolytic polishing, correlating the results with corrosion-fatigue strength testing performed in artificial fluoridated saliva. Specimens were also tested in air at room temperature to evaluate the effectiveness of the corrosion-fatigue test model. For each metal, 40 dumb-bell-shaped rods, 2.3 mm in diameter at the central segment, were cast. Conventional polishing was performed on 20 specimens of each metal following the manufacturer's instructions. A source of continuous electrical current was used for electrolytic polishing of the other 20 specimens of each metal, which were immersed in an electrolytic solution containing 5% fluoridric acid, 35% nitric acid, and 60% distilled water. Surface roughness, Ra (microm), was measured with a profilometer, and fatigue tests were carried out with a universal testing machine using a load 30% lower than the 0.2% offset yield strength. After failure, the fractured surfaces were examined using scanning electron microscopy. Surface roughness means were analyzed with a 2-way analysis of variance and the Tukey multiple comparisons test (alpha=.05). Electrolytic polishing (0.24 +/- 0.05 microm) provided significantly (P <.05) lower surface roughness values than conventional polishing (0.32 +/- 0.06 microm). Regardless of the polishing protocol, surface roughness of Ti-6Al-4V alloy (0.25 +/- 0.06 microm) was significantly lower (P <.05) than that of CP Ti (0.31 +/- 0.05 microm), and the fluoridated environment did not

  13. Corrosion and in vitro biocompatibility properties of cryomilled-spark plasma sintered commercially pure titanium.

    PubMed

    Dheda, Shehreen S; Kim, Yoon Kyung; Melnyk, Christopher; Liu, Wendy; Mohamed, Farghalli A

    2013-05-01

    Ti alloys, such as Ti6Al4V, are currently used in biomedical and dental implant applications. Ti alloys are used because they are stronger than commercially pure (CP) Ti due to the presence of alloying elements. However, toxicity of alloying elements during long-term use of implants is of concern. Another means of increasing the strength of materials is grain size refinement. In this study, ultrafine-grained (UFG, ~250 nm to 1 μm) CP Ti was produced by cryomilling followed by spark plasma sintering (SPS). Electrochemical impedance spectroscopy (EIS) and cell culture experiments were performed to compare the corrosion and biocompatibility properties of coarse grained (CG) Ti and UFG Ti. It was found that UFG Ti exhibited corrosion resistance comparable to CG Ti in Ringers solution. In addition, UFG Ti exhibited a reduced inflammatory response and enhanced cell adhesion compared to CG Ti. Investigation of surface roughness provided an explanation for enhanced cell adhesion.

  14. Fusion Welding Research.

    DTIC Science & Technology

    2014-09-26

    alloy for a variety of Navy systems. The fracture toughness of thick plate submerged arc welds is of particular interesc. This project is an...research S on welding processes. Studies include metal vapors in the arc , development of a high speed infrared temperature monitor, digital signal...analysis as a weld process monitor, convection in arc weld pools, droplet transfer and contact tip wear in gas metal arc welding of titanium, and fractd’re

  15. Friction behavior of network-structured CNT coating on pure titanium plate

    NASA Astrophysics Data System (ADS)

    Umeda, Junko; Fugetsu, Bunshi; Nishida, Erika; Miyaji, Hirofumi; Kondoh, Katsuyoshi

    2015-12-01

    Friction behavior of the network-structured CNTs coated pure Ti plate was evaluated by ball-on-disk wear test using SUS304 ball specimen under dry condition. The friction coefficient was significantly low and stable compared to the as-received Ti plate with no coating film. CNTs coating film had two important roles; self-lubrication and bearing effects to reduce the friction coefficient and carbon solid-solution hardening to improve the abrasive wear property of Ti plate. The annealing treatment at higher temperature (1123 K) was more effective to reduce the friction coefficient than that at lower temperature (973 K) because the Ti plate surface was uniformly covered with CNTs film even after sliding wear test. This is due to TiC interlayer formation via a reaction between Ti plate and carbon elements originated from CNTs during annealing. As a result, a strong interface bonding between CNTs film and Ti plate surface was obtained by higher temperature annealing treatment, and obstructed the detachment of CNTs film during wear test.

  16. Early laser-welded titanium frameworks supported by implants in the edentulous mandible: a 15-year comparative follow-up study.

    PubMed

    Ortorp, Anders; Jemt, Torsten

    2009-12-01

    Comparative long-term knowledge of different framework materials in the edentulous implant patient is not available for 15 years of follow-up. To report and compare a 15-year retrospective data on implant-supported prostheses in the edentulous mandible provided with laser-welded titanium frameworks (test) and gold alloy frameworks (control). Altogether, 155 patients were consecutively treated with abutment-level prostheses with two early generations of fixed laser-welded titanium frameworks (titanium group). Fifty-three selected patients with gold alloy castings formed the control group. Clinical and radiographic 15-year data were collected and compared for the groups. All patients who were followed up for 15 years (n = 72) still had a fixed prosthesis in the mandible at the termination of the study. The 15-year original prosthesis cumulative survival rate (CSR) was 89.2 and 100% for titanium and control frameworks (p = .057), respectively (overall CSR 91.7%). The overall 15-year implant CSR was 98.7%. The average 15-year bone loss was 0.59 mm (SD 0.56) and 0.98 mm (SD 0.64) for the test and control groups (p = .027), respectively. Few (1.3%) implants had >3.1-mm accumulated bone loss after 15 years. The most common complications for titanium frameworks were resin or veneer fractures and soft tissue inflammation. Fractures of the titanium metal frame were observed in 15.5% of the patients. More patients had framework fractures in the earliest titanium group (Ti-1 group) compared to the gold alloy group (p = .034). Loose and fractured implant screw components were few (2.4%). Predictable overall long-term results could be maintained with the present treatment modality. Fractures of the metal frames and remade prostheses were more common in the test group, and the gold alloy frameworks had a tendency to work better when compared with welded titanium frameworks during 15 years. However, on the average, more bone loss was observed for implants supporting gold alloy

  17. The Effect of Grain Size on Fatigue Crack Propagation in Commercial Pure Titanium Investigated by Acoustic Emission

    NASA Astrophysics Data System (ADS)

    Li, Lifei; Zhang, Zheng; Shen, Gongtian

    2015-07-01

    The effect of grain size on fatigue crack propagation and the corresponding acoustic emission (AE) characteristics of commercial pure titanium (CP-Ti) were investigated at room temperature. After a four-point bending fatigue testing, the fatigue features and AE source mechanisms were discussed, combined with microstructural and fractographic observations. The results showed that the increased grain size had little effect on the stable propagation rate of fatigue crack; however, a significant increase in the AE counts rate was observed. During crack stable propagation, the relationship between the AE counts rate and the fatigue stress intensity factor range was generally in accordance with the Pairs law, with the exception of some local fluctuations due to regional twin paling. While lenticular twins appeared dispersively along the crack, twin palings were observed occasionally at the edge of the crack. Twin paling occurrence was more frequent in the specimens with larger grains than in those with smaller grains. This suggests that twin discontinuously played a role in the fatigue process in this CP-Ti, and that the AE technique is sensitive to crack propagation and twinning events during fatigue.

  18. Effect of Laser Power and Scan Speed on Melt Pool Characteristics of Commercially Pure Titanium (CP-Ti)

    NASA Astrophysics Data System (ADS)

    Kusuma, Chandrakanth; Ahmed, Sazzad H.; Mian, Ahsan; Srinivasan, Raghavan

    2017-07-01

    Selective laser melting (SLM) is an additive manufacturing technique that creates complex parts by selectively melting metal powder layer-by-layer using a laser. In SLM, the process parameters decide the quality of the fabricated component. In this study, single beads of commercially pure titanium (CP-Ti) were melted on a substrate of the same material using an in-house built SLM machine. Multiple combinations of laser power and scan speed were used for single bead fabrication, while the laser beam diameter and powder layer thickness were kept constant. This experimental study investigated the influence of laser power, scan speed, and laser energy density on the melt pool formation, surface morphology, geometry (width and height), and hardness of solidified beads. In addition, the observed unfavorable effect such as inconsistency in melt pool width formation is discussed. The results show that the quality, geometry, and hardness of solidified melt pool are significantly affected by laser power, scanning speed, and laser energy density.

  19. Mechanical properties, surface morphology and stability of a modified commercially pure high strength titanium alloy for dental implants.

    PubMed

    Elias, Carlos Nelson; Fernandes, Daniel Jogaib; Resende, Celso R S; Roestel, Jochen

    2015-02-01

    Commercially pure titanium (cp Ti) and Ti-6Al-4V (Ti G5) alloy have limitations for biomedical application, due to lower mechanical strength and the possibility of ion release, respectively. The purpose of this work was to compare the properties of a modified cp Ti grade 4 (Ti G4 Hard) with those of available cp Ti and Ti G5 alloys. Bars, discs and dental implants made with Ti G2, G4, G5 and G4 Hard were used. Mechanical tests (tension, compression, hardness and torque) and roughness measurements were performed. Clinical trials were used to evaluate the biological behavior of dental implants made with Ti G4 Hard and Ti G4. The results of the mechanical tests showed that the mechanical strength of modified Ti G4 is higher than that of Ti G2, G4 and G5. Scanning electron microscopy analysis showed that modified Ti G4 after etching has better surface morphological features than conventional cp Ti and Ti G5. The clinical performances of Ti G4 and Ti G4 Hard were similar. The improvement of the mechanical properties of modified Ti G4 means that Ti G5 can be safely replaced by Ti G4 Hard without compromising the fracture resistance, with the advantage of not releasing toxic ions. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  20. Capillary flow weld-bonding

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Jones, R. J. (Inventor)

    1976-01-01

    The invention of a weld-bonding technique for titanium plates was described. This involves fastening at least two plates of titanium together using spot-welding and applying a bead of adhesive along the edge of the resistance spot-welded joint which upon heating, flows and fills the separation between the joint components.

  1. Filler wire for aluminum alloys and method of welding

    NASA Technical Reports Server (NTRS)

    Bjorkman, Jr., Gerald W. O. (Inventor); Cho, Alex (Inventor); Russell, Carolyn K. (Inventor)

    2003-01-01

    A weld filler wire chemistry has been developed for fusion welding 2195 aluminum-lithium. The weld filler wire chemistry is an aluminum-copper based alloy containing high additions of titanium and zirconium. The additions of titanium and zirconium reduce the crack susceptibility of aluminum alloy welds while producing good weld mechanical properties. The addition of silver further improves the weld properties of the weld filler wire. The reduced weld crack susceptibility enhances the repair weldability, including when planishing is required.

  2. Combined Laser Beam Welding and Brazing Process for Aluminium Titanium Hybrid Structures

    NASA Astrophysics Data System (ADS)

    Möller, F.; Grden, M.; Thomy, C.; Vollertsen, F.

    The current state of the art in light-weight construction is - for the case of aircraft structures - the use of either aluminium or titanium. Whereas aluminium is light-weight and less expensive, titanium offers superior corrosion properties at higher cost. In order to combine the advantages of both materials, a hybrid Ti-Al structure is proposed for e.g. seat-track application. In this paper, an overview of the results from this research work and the accompanying thermo-mechanical simulations will be reported and discussed. On the basis of the development of an appropriate system technology, the process development will be described, focusing on the main influencing parameters of the process on joint properties.

  3. [Study on the in vitro release behavior of bovine serum albumin from calcium phosphate coating on pure titanium surface].

    PubMed

    Zhu, Xiaojing; Wang, Yan; Zhang, Hui; Teng, Wei; Ning, Chengyun; Zheng, Huade

    2014-09-01

    To study the incorporation rate and release behavior of bovine serum albumin (BSA) incorporated into the calcium phosphate coating by biomimetic deposition, as well as the physical and chemical properties of the hybrid coating, and to provide experimental basis for the fabrication of growth factor/biomimetic calcium phosphate coating and exploration for the loading/release behavior of growth factors. Pure titanium specimens were immersed into saturated calcium phosphate solutions(SCP) containing no BSA (controlled group) and 3 different concentrations of BSA (experimental groups) : 1, 10 and 100 mg/L. Biomimetic calcium phosphate coating was formed on titanium surface and BSA was incorporated into the coating through co-deposition. The topography of the specimen was observed using scanning electron microscopy (SEM). Chemical structure and phase composition of coatings were detected by Fourier infrared spectroscopy (FTIR) analysis and X-ray diffraction (XRD) respectively. BSA incorporation rate and release profile were determined by bicinchoninic acid protein assay kit. The biomimetic calcium phosphate coating was mainly composed of hydroxyapatite and octacalcium phosphate. BSA was successfully incorporated into the calcium phosphate coatings in all the 3 experimental groups. With the increase of BSA concentration, plate-like units of the coatings were turned into small grid structure. BSA incorporation rates of the three experimental groups were (72.4 ± 2.4)%, (62.3 ± 0.9)% and (42.2 ± 1.7)% respectively. The in vitro release test showed that all three BSA release profiles could be divided into two significant different stages: early burst release stage and later sustained release stage. The amount of BSA release of the 3 experimental groups in 24 h and 30 d were (1.57 ± 0.09), (8.82 ± 0.93), (140.24 ± 3.12) µg, and (2.39 ± 0.29), (14.39 ± 0.70), (151.06 ± 2.00) µg respectively. Biomimetic calcium phosphate coating can be used as an effective carrier for

  4. Investigation of Interface Bonding Mechanism of an Explosively Welded Tri-Metal Titanium/Aluminum/Magnesium Plate by Nanoindentation

    NASA Astrophysics Data System (ADS)

    Zhang, T. T.; Wang, W. X.; Zhou, J.; Cao, X. Q.; Yan, Z. F.; Wei, Y.; Zhang, W.

    2017-08-01

    A tri-metal titanium/aluminum/magnesium (Ti/Al/Mg) cladding plate, with an aluminum alloy interlayer plate, was fabricated for the first time by explosive welding. Nanoindentation tests and associated microstructure analysis were conducted to investigate the interface bonding mechanisms of the Ti/Al/Mg cladding plate. A periodic wavy bonding interface (with an amplitude of approximately 30 μm and a wavelength of approximately 160 μm) without a molten zone was formed between the Ti and Al plates. The bonding interface between the Al and the Mg demonstrated a similar wavy shape, but the wave at this location was much larger with an amplitude of approximately 390 μm and a wavelength of approximately 1580 μm, and some localized melted zones also existed at this location. The formation of the wavy interface was found to result from a severe deformation at the interface, which was caused by the strong impact or collision. The nanoindentation tests showed that the material hardness decreased with increasing distance from the bonding interface. Material hardness at a location was found to be correlated with the degree of plastic deformation at that site. A larger plastic deformation was correlated with an increase in hardness.

  5. Structure and properties of commercially pure titanium nitrided in the plasma of a low-pressure gas discharge produced by a PINK plasma generator

    NASA Astrophysics Data System (ADS)

    Ivanov, Yu F.; Akhmadeev, Yu H.; Lopatin, I. V.; Petrikova, E. A.; Krysina, V.; Koval, N. N.

    2015-11-01

    The paper analyzes the surface structure and properties of commercially pure VT1-0 titanium nitrided in the plasma of a low-pressure gas discharge produced by a PINK plasma generator. The analysis demonstrates that the friction coefficient of the nitrided material decreases more than four times and its wear resistance and microhardness increases more than eight and three times, respectively. The physical mechanisms responsible for the enhancement of strength and tribological properties of the material are discussed.

  6. Characterization of Friction Welded Titanium Alloy and Stainless Steel with a Novel Interlayer Geometry

    NASA Astrophysics Data System (ADS)

    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.

  7. Effect of the combination of different welding parameters on melting characteristics of grade 1 titanium with a pulsed Nd-Yag laser.

    PubMed

    Bertrand, C; Laplanche, O; Rocca, J P; Le Petitcorps, Y; Nammour, S

    2007-11-01

    The laser is a very attractive tool for joining dental metallic alloys. However, the choice of the setting parameters can hardly influence the welding performances. The aim of this research was to evaluate the impact of several parameters (pulse shaping, pulse frequency, focal spot size...) on the quality of the microstructure. Grade 1 titanium plates have been welded with a pulsed Nd-Yag laser. Suitable power, pulse duration, focal spot size, and flow of argon gas were fixed by the operator. Five different pulse shapes and three pulse frequencies were investigated. Two pulse shapes available on this laser unit were eliminated because they considerably hardened the metal. As the pulse frequency rose, the metal was more and more ejected, and a plasma on the surface of the metal increased the oxygen contamination in the welded area. Frequencies of 1 or 2 Hz are optimum for a dental use. Three pulse shapes can be used for titanium but the rectangular shape gives better results.

  8. Laser-Modified Surface Enhances Osseointegration and Biomechanical Anchorage of Commercially Pure Titanium Implants for Bone-Anchored Hearing Systems

    PubMed Central

    Omar, Omar; Simonsson, Hanna; Palmquist, Anders; Thomsen, Peter

    2016-01-01

    Osseointegrated implants inserted in the temporal bone are a vital component of bone-anchored hearing systems (BAHS). Despite low implant failure levels, early loading protocols and simplified procedures necessitate the application of implants which promote bone formation, bone bonding and biomechanical stability. Here, screw-shaped, commercially pure titanium implants were selectively laser ablated within the thread valley using an Nd:YAG laser to produce a microtopography with a superimposed nanotexture and a thickened surface oxide layer. State-of-the-art machined implants served as controls. After eight weeks’ implantation in rabbit tibiae, resonance frequency analysis (RFA) values increased from insertion to retrieval for both implant types, while removal torque (RTQ) measurements showed 153% higher biomechanical anchorage of the laser-modified implants. Comparably high bone area (BA) and bone-implant contact (BIC) were recorded for both implant types but with distinctly different failure patterns following biomechanical testing. Fracture lines appeared within the bone ~30–50 μm from the laser-modified surface, while separation occurred at the bone-implant interface for the machined surface. Strong correlations were found between RTQ and BIC and between RFA at retrieval and BA. In the endosteal threads, where all the bone had formed de novo, the extracellular matrix composition, the mineralised bone area and osteocyte densities were comparable for the two types of implant. Using resin cast etching, osteocyte canaliculi were observed directly approaching the laser-modified implant surface. Transmission electron microscopy showed canaliculi in close proximity to the laser-modified surface, in addition to a highly ordered arrangement of collagen fibrils aligned parallel to the implant surface contour. It is concluded that the physico-chemical surface properties of laser-modified surfaces (thicker oxide, micro- and nanoscale texture) promote bone bonding

  9. Laser-Modified Surface Enhances Osseointegration and Biomechanical Anchorage of Commercially Pure Titanium Implants for Bone-Anchored Hearing Systems.

    PubMed

    Shah, Furqan A; Johansson, Martin L; Omar, Omar; Simonsson, Hanna; Palmquist, Anders; Thomsen, Peter

    2016-01-01

    Osseointegrated implants inserted in the temporal bone are a vital component of bone-anchored hearing systems (BAHS). Despite low implant failure levels, early loading protocols and simplified procedures necessitate the application of implants which promote bone formation, bone bonding and biomechanical stability. Here, screw-shaped, commercially pure titanium implants were selectively laser ablated within the thread valley using an Nd:YAG laser to produce a microtopography with a superimposed nanotexture and a thickened surface oxide layer. State-of-the-art machined implants served as controls. After eight weeks' implantation in rabbit tibiae, resonance frequency analysis (RFA) values increased from insertion to retrieval for both implant types, while removal torque (RTQ) measurements showed 153% higher biomechanical anchorage of the laser-modified implants. Comparably high bone area (BA) and bone-implant contact (BIC) were recorded for both implant types but with distinctly different failure patterns following biomechanical testing. Fracture lines appeared within the bone ~30-50 μm from the laser-modified surface, while separation occurred at the bone-implant interface for the machined surface. Strong correlations were found between RTQ and BIC and between RFA at retrieval and BA. In the endosteal threads, where all the bone had formed de novo, the extracellular matrix composition, the mineralised bone area and osteocyte densities were comparable for the two types of implant. Using resin cast etching, osteocyte canaliculi were observed directly approaching the laser-modified implant surface. Transmission electron microscopy showed canaliculi in close proximity to the laser-modified surface, in addition to a highly ordered arrangement of collagen fibrils aligned parallel to the implant surface contour. It is concluded that the physico-chemical surface properties of laser-modified surfaces (thicker oxide, micro- and nanoscale texture) promote bone bonding which

  10. Comparative study of the shear bond strength of various veneering materials on grade II commercially pure titanium.

    PubMed

    Lee, Eun-Young; Jun, Sul-Gi; Wright, Robert F; Park, Eun-Jin

    2015-02-01

    To compare the shear bond strength of various veneering materials to grade II commercially pure titanium (CP-Ti). Thirty specimens of CP-Ti disc with 9 mm diameter and 10 mm height were divided into three experimental groups. Each group was bonded to heat-polymerized acrylic resin (Lucitone 199), porcelain (Triceram), and indirect composite (Sinfony) with 7 mm diameter and 2 mm height. For the control group (n=10), Lucitone 199 were applied on type IV gold alloy castings. All samples were thermocycled for 5000 cycles in 5-55℃ water. The maximum shear bond strength (MPa) was measured with a Universal Testing Machine. After the shear bond strength test, the failure mode was assessed with an optic microscope and a scanning electron microscope. Statistical analysis was carried out with a Kruskal-Wallis Test and Mann-Whitney Test. The mean shear bond strength and standard deviations for experimental groups were as follows: Ti-Lucitone 199 (12.11 ± 4.44 MPa); Ti-Triceram (11.09 ± 1.66 MPa); Ti-Sinfony (4.32 ± 0.64 MPa). All of these experimental groups showed lower shear bond strength than the control group (16.14 ± 1.89 MPa). However, there was no statistically significant difference between the Ti-Lucitone 199 group and the control group, and the Ti-Lucitone 199 group and the Ti-Triceram group. Most of the failure patterns in all experimental groups were adhesive failures. The shear bond strength of veneering materials such as heat-polymerized acrylic resin, porcelain, and indirect composite to CP-Ti was compatible to that of heatpolymerized acrylic resin to cast gold alloy.

  11. A bone-like precoating strategy for implants: collagen immobilization and mineralization on pure titanium implant surface.

    PubMed

    Munisamy, S; Vaidyanathan, T K; Vaidyanathan, J

    2008-01-01

    Many surface modification strategies are currently of interest in improving integration of implants to bone. An in vitro precoating of a bone-like mineralized layer of immobilized collagen on the implant surface is a potentially valuable approach to improve host acceptance of the implant. The goal of this investigation was to develop a method to precoat in vitro a bone-like mineralized collagen layer on a pure titanium dental implant surface. The study was conducted on acid-etched and nonetched surfaces of screw implants. Initially, a procedure was standardized to self-assemble collagen from a collagen solution. In subsequent experiments, the implant was also placed inside the solution, and after 3 days, collagen was found to be coated on the implant surface. Mineralization of the collagen gel as well as collagen coating on the implant was carried out by calcium phosphate precipitation from a mineralizing solution of calcium chloride containing polyvinyl phosphonic acid and polyaspartic acid, which served as polyanionic additives to help disperse the precipitation and template mineral nucleation. The implant was kept in the mineralizing solution and maintained for 2 weeks in an incubator at 37 degrees C with a phosphate vapor phase generated from a vial containing dihydrogen ammonium phosphate in the incubator. Scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy analysis confirmed the coated layer to be a biomimetic bone-like mineralized type 1 collagen. Initial studies using osteoblast-like cells indicated cellular attachment on the modified surface. The method appears to be a promising way to generate in vitro a bone-like layer on the implant surface.

  12. The effect of static applied potential on the 24-hour impedance behavior of commercially pure titanium in simulated biological conditions.

    PubMed

    Ehrensberger, Mark T; Gilbert, Jeremy L

    2010-04-01

    Potential step impedance analysis was utilized to evaluate the electrochemical impedance of commercially pure titanium (cpTi) samples that were polarized to static potentials (range from -1000 mV to +1000 mV vs. Ag/AgCl) and immersed in physiologically relevant electrolytes [phosphate buffered saline (PBS) and cell culture medium with 10% fetal bovine serum (AMEM + FBS)] for 24 hrs. The cpTi impedance outcomes were a complex function of voltage, solution constituents, and immersion time. In the 0 mV to +1000 mV range, oxide growth was observed over 24 hr immersion in both solutions based on decreasing current density (approximately 10(-6) A/cm(2) to approximately 10(-8) A/cm(2)) and increasing R(p) (200 kOmega cm(2) to approximately 10 MOmega cm(2)). Below 0 mV, the 24 hr R(p) decreased with negative potential to approximately 15 kOmega cm(2). After 24 hr immersion, oxide dissolution and/or adsorption of organic species caused the capacitance to increase at -1000 mV (AMEM + FBS & PBS) and at -600 mV (AMEM + FBS only). Twenty-four hours of immersion in AMEM + FBS at -1000 mV and -600 mV produced a surface coloration that is likely due to alteration of oxide valance state and/or doping level. This work shows that Ti surface oxide and its electrochemical behavior can be altered dramatically under sustained cathodic potentials.

  13. The effect of fretting associated periodic cathodic potential shifts on the electrochemistry and in vitro biocompatibility of commercially pure titanium.

    PubMed

    Ciolko, Alexandra A; Tobias, Menachem; Ehrensberger, Mark T

    2016-11-01

    This study explored how periodic cathodic polarization of commercially pure titanium (cpTi) alters its electrochemical properties and biocompatibility. MC3T3-E1 preosteoblast cells were cultured directly on cpTi samples and maintained at open circuit potential (OCP) for 24 h followed by an additional 24-h sequence of periodic cathodic polarization to -1000 or -750 mV (vs. Ag/AgCl) for 1 s followed by a 5-s recovery at OCP. Control experiments were performed where the samples were maintained at OCP throughout the entire test. Subsequent electrochemical impedance spectroscopy revealed both of the periodic cathodic polarization conditions significantly reduced the polarization resistance (Rp ), while only the -1000 mV condition significantly increased the capacitance (C) as compared to the controls. Scanning electron micrographs showed that the cells were fragmented and balled up on the samples periodically shifted to -1000 mV as compared to the cells that were well spread on the controls and samples periodically shifted to -750 mV. Additionally, live/dead fluorescence microscopy revealed that periodic polarizations to -1000 mV reduced cell viability to around 12% as compared to the greater than 95% cell viability observed on the controls and samples periodically polarized to -750 mV. This work showed that periodic cathodic potential shifts can notably alter the electrochemical behavior of cpTi and the viability and morphology of cells seeded directly onto its surface. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1591-1601, 2016.

  14. SCC INITIATION AND GROWTH RATE STUDIES ON TITANIUM GRADE 7 AND BASE METAL, WELDED, AND AGED ALLOY 22 IN CONCENTRATED GROUNDWATER

    SciTech Connect

    J.H. Payer

    2005-08-01

    The stress corrosion crack initiation and growth rate response was evaluated on as-received, as-welded, cold worked and aged Alloy 22 (UNS N06022) and titanium Grades 7 (UNS R52400), 28 (UNS R55323) and 29 (UNS R56404) at 105-165 C in various aerated, concentrated groundwater environments. Time-to-failure experiments on actively-loaded tensile specimens at 105 C evaluated the effects of applied stress, welding, surface finish, shot peening, cold work, crevicing, and aging treatments in Alloy 22 (UNS N06022), and found these materials to be highly resistant to SCC (none observed). Long-term U-bend data at 165 C corroborated these findings. Titanium Grade 7 and stainless steels were also included in the 105 C test matrix. Long term crack growth rate data showed stable crack growth in titanium Grade 7. Recent creep tests in air confirm literature data that these alloys are quite susceptible to creep failure, even below the yield stress, and it is unclear whether cracking in SCC tests is only accelerated by the creep response, or whether creep is responsible for cracking. Alloy 22 exhibited stable growth rates under ''gentle'' cyclic loading, but was prone to crack arrest at fully static loading. No effect of Pb additions was observed.

  15. Evaluation of Mechanical Properties and Marginal Fit of Crowns Fabricated Using Commercially Pure Titanium and FUS-Invest

    PubMed Central

    Wu, Jinshuang; Wang, Xianli; Xing, Helin; Guo, Tianwen; Dong, Chaofang

    2017-01-01

    This study investigated the mechanical properties and single crown accuracy of the tailor-made Fourth University Stomatology investment (FUS-invest) for casting titanium. Background. Current investment for casting titanium is not optimal for obtaining high-quality castings, and the commercially available titanium investment is costly. Methods. Titanium specimens were cast using the tailor-made FUS-invest. The mechanical properties were tested using a universal testing machine. Fractured castings were characterized by energy-dispersive spectroscopy. 19 titanium crowns were produced using FUS-invest and another 19 by Symbion. The accuracy of crowns was evaluated. Results. The mechanical properties of the titanium cast by FUS-invest were elastic modulus 125.6 ± 8.8 GPa, yield strength 567.5 ± 11.1 MPa, tensile strength 671.2 ± 15.6 MPa, and elongation 4.6 ± 0.2%. For marginal fit, no significant difference (P > 0.05) was found at four marker points of each group. For internal fit, no significant difference (P > 0.05) was found between two groups, whereas significant difference (P < 0.01) was found at different mark point of each group. Conclusions. The mechanical properties of titanium casted using FUS-invest fulfilled the ISO 9693 criteria. The marginal and internal fit of the titanium crowns using either the FUS-invest or Symbion were similar. PMID:28913355

  16. Effect of Heat Input on the Tensile Damage Evolution in Pulsed Laser Welded Ti6Al4V Titanium Sheets

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Gao, Xiaolong; Zhang, Jianxun

    2016-11-01

    The present paper is focused on studying the effect of heat input on the tensile damage evolution of pulsed Nd:YAG laser welding of Ti6Al4V alloy under monotonic loading. To analyze the reasons that the tensile fracture site of the pulsed-laser-welded Ti6Al4V sheet joints changes with the heat input under monotonic loading, the microstructure of the sample with different nominal strain values was investigated by in situ observation. Experiment results show that the tensile ductility and fatigue life of welded joints with low heat input are higher than that of welded joints with high heat input. Under tensile loads, the critical engineering strain for crack initiation is much lower in the welded joint with high heat input than in the welded joints with low and medium heat input. And the microstructural damage accumulation is much faster in the fusion zone than in the base metal for the welded joints with high input, whereas the microstructural damage accumulation is much faster in the base metal than in the fusion zone for the welded joints with low input. Consequently, the welded joints fractured in the fusion zone for the welds with high heat input, whereas the welded joints ruptured in the base metal for the welds with low heat input. It is proved that the fine grain microstructure produced by low heat input can improve the critical nominal strain for crack initiation and the resistance ability of microstructural damage.

  17. Microstructures and Mechanical Properties of Electron Beam-Welded Titanium-Steel Joints with Vanadium, Nickel, Copper and Silver Filler Metals

    NASA Astrophysics Data System (ADS)

    Wang, Ting; Zhang, Binggang; Wang, Houqin; Feng, Jicai

    2014-04-01

    Electron beam welding experiments of titanium alloy to stainless steel with V, Ni, Cu and Ag filler metals were carried out. The interfacial microstructures of the joints were examined by optical microscopy, scanning electron microscopy, and x-ray diffraction analysis. Mechanical properties of the joints were evaluated according to tensile strength and microhardness. The results showed that all the filler metals were helpful to restrain the Ti-Fe intermetallics formed in the Ti/Fe joint. The welds with different filler metals were all characterized by solid solution and interfacial intermetallics. And the type of solid solution and interfacial intermetallics were depended on the metallurgical reactions between the filler metals and base metals. The interfacial intermetallics were Fe2Ti + Ni3Ti + NiTi2, TiFe, Ti2Ag, and Cu2Ti + CuTi + CuTi2 in the joints welded with Ni, V, Ag, and Cu filler metals, respectively. The tensile strengths of the joints were primarily determined by the hardness of the interfacial intermetallics. The highest tensile strength was obtained in the joint welded with silver filler metal, which is about 310 MPa.

  18. Microstructure characteristics and mechanical properties of laser-welded joint of γ-TiAl alloy with pure Ti filler metal

    NASA Astrophysics Data System (ADS)

    Cai, Xiaolong; Sun, Daqian; Li, Hongmei; Guo, Hongling; Gu, Xiaoyan; Zhao, Zhuo

    2017-12-01

    γ-TiAl alloy was successfully welded using pure Ti filler metal by laser. The microstructures, element distribution and phase composition of the joint were investigated by SEM, EDS and XRD, and the mechanical properties of the joints were evaluated by nanoindentation and tensile strength tests. Crack-free joints were obtained by using Ti filler metal. The weld zone mainly contained of α2-Ti3Al phase and a small amount of Ti2Al phases. The hardness values in the weld zone were higher than that of base metal (BM) due to the formation of α2-Ti3Al phase, but for the modulus values were just the reverse. The tensile strength and elongation of the joints were 288 MPa and 2.19%, respectively, accounting for 74.8% and 94.0% of the BM, respectively. The joint fracture surface exhibited typical brittle fracture morphology, and Ti2Al and TiAl2 particle phases can be seen on the fracture surface.

  19. Characterization of microstructure and mechanical property of pure titanium with different Fe addition processed by severe plastic deformation and subsequent annealing

    NASA Astrophysics Data System (ADS)

    Deng, Guanyu; Bhattacharjee, Tilak; Chong, Yan; Zheng, Ruixiao; Bai, Yu; Shibata, Akinobu; Tsuji, Nobuhiro

    2017-05-01

    Titanium and Ti-alloys are widely used in the marine, aerospace, and biomedical industries due to their high strength to weight ratio, excellent corrosion resistance, and biocompatibility. Increasing the strength level of pure Ti via grain refinement without a considerable decrease in ductility is an attractive approach. Fabrication of nanostructured or ultrafine grained (UFG) metals using severe plastic deformation (SPD) techniques has attracted a lot of interest in the last two decades. The main purpose of the present study is to explore the influence of Fe addition in grain refinement in pure Ti. As-cast pure Ti with two different levels of Fe was firstly deformed by high pressure torsion (HPT) up to 10 rotations at room temperature, and then annealed in a vacuum at a temperature of 500 °C for half an hour. Detailed microstructures were characterized by transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD), and mechanical property was examined by microhardness test.

  20. Submerged-arc welding slags: characterization and leaching strategies for the removal of aluminum and titanium.

    PubMed

    Annoni, Raquel; Souza, Poliana Santos; Petrániková, Martina; Miskufova, Andrea; Havlík, Tomáš; Mansur, Marcelo Borges

    2013-01-15

    In the present study, submerged-arc welding slags were characterized by applying a variety of methods, including X-ray fluorescence, X-ray diffraction, particle size, Raman spectroscopy, and scanning electron microscope with energy dispersive X-ray analysis. The content of Al proved to be quite similar within neutral and acid slags (10-14%), while that of Ti proved to be much higher in acid slags (approximately 10%) than in neutral slags (<1%). The presence of spinel structures associated with Al species could also be identified in the analyzed samples. This characterization study was accompanied by leaching tests performed under changing operating conditions in an attempt to evaluate to what extent the Al and Ti bearing components could be removed from the slags. The leaching work involved three distinct strategies: (i) NaOH leaching followed by H(2)SO(4) leaching, (ii) acid leaching (HCl and H(2)SO(4)) using oxidizing/reducing agents, and (iii) slag calcination followed by H(2)SO(4) leaching. In the best result, 80% of Al was extracted in one single leaching stage after calcination of the acid slag with NaCl+C at 900 °C. By contrast, the removal of Ti proved to be unsatisfactory. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Physicochemical state of the nanotopographic surface of commercially pure titanium following anodization-hydrothermal treatment reveals significantly improved hydrophilicity and surface energy profiles.

    PubMed

    Takebe, Jun; Ito, Shigeki; Miura, Shingo; Miyata, Kyohei; Ishibashi, Kanji

    2012-01-01

    A method of coating commercially pure titanium (cpTi) implants with a highly crystalline, thin hydroxyapatite (HA) layer using discharge anodic oxidation followed by hydrothermal treatment (Spark discharged Anodic oxidation treatment ; SA-treated cpTi) has been reported for use in clinical dentistry. We hypothesized that a thin HA layer with high crystallinity and nanostructured anodic titanium oxide film on such SA-treated cpTi implant surfaces might be a crucial function of their surface-specific potential energy. To test this, we analyzed anodic oxide (AO) cpTi and SA-treated cpTi disks by SEM and AFM. Contact angles and surface free energy of each disk surface was measured using FAMAS software. High-magnification SEM and AFM revealed the nanotopographic structure of the anodic titanium oxide film on SA-treated cpTi; however, this was not observed on the AO cpTi surface. The contact angle and surface free energy measurements were also significantly different between AO cpTi and SA-treated cpTi surfaces (Tukey's, P<0.05). These data indicated that the change of physicochemical properties of an anodic titanium oxide film with HA crystals on an SA-treated cpTi surface may play a key role in the phenomenon of osteoconduction during the process of osseointegration.

  2. Effects of sandblasting, H2SO4/HCl etching, and phosphate primer application on bond strength of veneering resin composite to commercially pure titanium grade 4.

    PubMed

    Egoshi, Takafumi; Taira, Yohsuke; Soeno, Kohyoh; Sawase, Takashi

    2013-01-01

    This study investigated the effects of surface treatments on the bond strength of a resin composite to a commercially pure titanium. The bonding surfaces of all titanium specimens were ground with 1,000-grit silicon carbide paper and then subjected to one or more of these surface treatments: sandblasting with alumina (sand), etching with 45wt% H2SO4 and 15wt% HCl (SH-etchant) at 70°C for 10 min, and/or phosphate primer (MDP-primer) application. Specimens not subjected to any surface treatment were used as controls. After resin composite veneer placement and 24-h water immersion, the shear bond strengths of the specimens in descending order were: sand/SH-etchant/MDP-primer, sand/SH-etchant/no primer, no sand/SH-etchant/MDP-primer, sand/no etch/MDP-primer, no sand/SH-etchant/no primer, sand/no etch/no primer, no sand/no etch/MDP-primer, no sand/no etch/no primer. Scanning electron microscope observations revealed that sandblasting and SH-etchant created many micro- and nanoscale cavities on the titanium surface. Results showed that a combined use of sandblasting, SH-etchant, and MDP-primer application had a cooperative effect on titanium bonding.

  3. Combined effect of grain refinement and surface modification of pure titanium on the attachment of mesenchymal stem cells and osteoblast-like SaOS-2 cells.

    PubMed

    Medvedev, A E; Neumann, A; Ng, H P; Lapovok, R; Kasper, C; Lowe, T C; Anumalasetty, V N; Estrin, Y

    2017-02-01

    Surface modification is an important step in production of medical implants. Surface roughening creates additional surface area to enhance the bonding between the implant and the bone. Recent research provided a means to alter the microstructure of titanium by severe plastic deformation (SPD) in order to increase its strength, and thereby reduce the size of the implants (specifically, their diameter). The purpose of the present study was to examine the effect of bulk microstructure of commercially pure titanium with coarse-grained (CG) and ultrafine-grained (UFG) bulk structure on the surface state of these materials after surface modification by sand blasting and acid etching (SLA). It was shown that SLA-modified surface characteristics, in particular, roughness, chemistry, and wettability, were affected by prior SPD processing. Additionally, biocompatibility of UFG titanium was examined using osteosarcoma cell line SaOS-2 and primary human adipose-derived mesenchymal stem cell (adMSC) cultures. Enhanced cell viability as well as increased matrix mineralization during osteogenic differentiation of MSCs on the surface of ultrafine-grained titanium was shown. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Study of weld offset in longitudinally welded SSME HPFTP inlet

    NASA Technical Reports Server (NTRS)

    Min, J. B.; Spanyer, K. S.; Brunair, R. M.

    1992-01-01

    Welded joints are an essential part of rocket engine structures such as the Space Shuttle Main Engine (SSME) turbopumps. Defects produced in the welding process can be detrimental to weld performance. Recently, review of the SSME high pressure fuel turbopump (HPFTP) titanium inlet X-rays revealed several weld discrepancies such as penetrameter density issues, film processing discrepancies, weld width discrepancies, porosity, lack of fusion, and weld offsets. Currently, the sensitivity of welded structures to defects is of concern. From a fatigue standpoint, weld offset may have a serious effect since local yielding, in general, aggravates cyclic stress effects. Therefore, the weld offset issue is considered in this report. Using the FEM and beamlike plate approximations, parametric studies were conducted to determine the influence of weld offsets and a variation of weld widths in longitudinally welded cylindrical structures with equal wall thicknesses on both sides of the joint. Following the study, some conclusions are derived for the weld offsets.

  5. Fabrication of nanotube arrays on commercially pure titanium and their apatite-forming ability in a simulated body fluid

    SciTech Connect

    Hsu, Hsueh-Chuan; Wu, Shih-Ching; Hsu, Shih-Kuang; Chang, Yu-Chen; Ho, Wen-Fu

    2015-02-15

    In this study, we investigated self-organized TiO{sub 2} nanotubes that were grown using anodization of commercially pure titanium at 5 V or 10 V in NH{sub 4}F/NaCl electrolyte. The nanotube arrays were annealed at 450 °C for 3 h to convert the amorphous nanotubes to anatase and then they were immersed in simulated body fluid at 37 °C for 0.5, 1, and 14 days. The purpose of this experiment was to evaluate the apatite-formation abilities of anodized Ti nanotubes with different tube diameters and lengths. The nanotubes that formed on the surfaces of Ti were examined using a field emission scanning electron microscope, X-ray diffraction, and X-ray photoelectron spectroscope. When the anodizing potential was increased from 5 V to 10 V, the pore diameter of the nanotube increased from approximately 24–30 nm to 35–53 nm, and the tube length increased from approximately 590 nm to 730 nm. In vitro testing of the heat-treated nanotube arrays indicated that Ca-P formation occurred after only 1 day of immersion in simulated body fluid. This result was particularly apparent in the samples that were anodized at 10 V. It was also found that the thickness of the Ca-P layer increases as the applied potential for anodized c.p. Ti increases. The average thickness of the Ca-P layer on Ti that was anodized at 5 V and 10 V was approximately 170 nm and 190 nm, respectively, after immersion in simulated body fluid for 14 days. - Highlights: • TiO{sub 2} nanotube on Ti surface was formed by anodic oxidation in a NaCl/NH{sub 4}F solution. • TiO{sub 2} layers show a tube length of 590 nm and 730 nm at 5 V and 10 V, respectively. • After soaking in SBF, Ca-P layer completely covered the entire nanotubular surfaces. • The Ca-P layer was thicker on the Ti surface anodized at 10 V.

  6. Preparation and characterization of porous bioceramic layers on pure titanium surfaces obtained by micro-arc oxidation process

    NASA Astrophysics Data System (ADS)

    Chien, Chi-Sheng; Hung, Yu-Chien; Hong, Ting-Fu; Wu, Chung-Chun; Kuo, Tsung-Yuan; Lee, Tzer-Min; Liao, Tze-Yuan; Lin, Huan-Chang; Chuang, Cheng-Hsin

    2017-03-01

    Fluorapatite (FA) has better chemical and thermal stability than hydroxyapatite (HA), and has thus attracted significant interest for biomaterial applications in recent years. In this study, porous bioceramic layers were prepared on pure titanium surfaces using a micro-arc oxidation (MAO) technique with an applied voltage of 450 V and an oxidation time of 5 min. The MAO process was performed using three different electrolyte solutions containing calcium fluoride (CaF2), calcium acetate monohydrate (Ca(CH3COO)2·H2O), and sodium phosphate monobasic dihydrate (NaH2PO4·2H2O) mixed in ratios of 0:2:1, 1:1:1, and 2:0:1, respectively. The surface morphology, composition, micro-hardness, porosity, and biological properties of the various MAO coatings were examined and compared. The results showed that as the CaF2/Ca(CH3COO)2·H2O ratio increased, the elemental composition of the MAO coating transformed from HA, A-TiO2 (Anatase) and R-TiO2 (Rutile); to A-TiO2, R-TiO2, and a small amount of HA; and finally A-TiO2, R-TiO2, CaF2, TiP2O5, and FA. The change in elemental composition was accompanied by a higher micro-hardness and a lower porosity. The coatings exhibited a similar in vitro bioactivity performance during immersion in simulated body fluid for 7-28 days. Furthermore, for in initial in vitro biocompatibility tests performed for 24 h using Dulbecco's Modified Eagle Medium (DMEM) supplement containing 10%Fetal bovine serum, the attachment and spreading of osteoblast-like osteosarcoma MG63 cells were found to increase slightly with an increasing CaF2/Ca(CH3COO)2·H2O ratio. In general, the results presented in this study show that all three MAO coatings possess a certain degree of in vitro bioactivity and biocompatibility.

  7. Microstructural Evolution of the Interface Between Pure Titanium and Low Melting Point Zr-Ti-Ni(Cu) Filler Metals

    NASA Astrophysics Data System (ADS)

    Lee, Dongmyoung; Sun, Juhyun; Kang, Donghan; Shin, Seungyoung; Hong, Juhwa

    2014-12-01

    Low melting point Zr-based filler metals with melting point depressants (MPDs) such as Cu and Ni elements are used for titanium brazing. However, the phase transition of the filler metals in the titanium joint needs to be explained, since the main element of Zr in the filler metals differs from that of the parent titanium alloys. In addition, since the MPDs easily form brittle intermetallics, that deteriorate joint properties, the phase evolution they cause needs to be studied. Zr-based filler metals having Cu content from 0 to 12 at. pct and Ni content from 12 to 24 at. pct with a melting temperature range of 1062 K to 1082 K (789 °C to 809 °C) were wetting-tested on a titanium plate to investigate the phase transformation and evolution at the interface between the titanium plate and the filler metals. In the interface, the alloys system with Zr, Zr2Ni, and (Ti,Zr)2Ni phases was easily changed to a Ti-based alloy system with Ti, Ti2Ni, and (Ti,Zr)2Ni phases, by the local melting of parent titanium. The dissolution depths of the parent metal were increased with increasing Ni content in the filler metals because Ni has a faster diffusion rate than Cu. Instead, slow diffusion of Cu into titanium substrate leads to the accumulation of Cu at the molten zone of the interface, which could form undesirable Ti x Cu y intermetallics. This study confirmed that Zr-based filler metals are compatible with the parent titanium metal with the minimum content of MPDs.

  8. Characterization of solid-phase welds between Ti-6Al-2Sn-4Zr-2Mo-0. 01Si and Ti-13. 5A1-21. 5Nb titanium aluminide

    SciTech Connect

    Baeslack, W.A. III; Juhas, M.; Fraser, H.L. ); Broderick, T.F. . Materials Directorate)

    1994-12-01

    Dissimilar-alloy welds have been produced between Ti-6Al-2Sn-4Zr-2Mo-0.1Si (wt.%) and Ti-13.5Al-21.5Nb (wt.%) titanium aluminide using three different solid-phase welding processes that create significantly different thermo-mechanical conditions at the weld interface. Exposure to supertransus temperatures, appreciable deformation and rapid cooling of the weld interface region during linear-friction welding promote dynamic recrystallization of beta grains and beta decomposition to fine martensitic products. In contrast, diffusion welding at temperatures below the base metal beta transus temperatures and at relatively low pressures minimizes deformation and microstructural variations in the weld interface region relative to the unaffected base metal. During capacitor-discharge resistance spot welding, extremely rapid heating of the weld interface region to near-solidus temperatures, and subsequent rapid cooling, result in the formation of a metastable, ordered-beta microstructure in the Ti-13.5ASl-21.5Nb and fine alpha-prime martensite in the Ti-6Al-2Sn-4Zr-2Mo-0.1Si.

  9. Titanium 2013

    USGS Publications Warehouse

    2014-01-01

    Titanium is the ninth most abundant element in the earth's crust and can be found in nearly all rocks and sediments. It is a lithophile element with a strong affinity for oxygen and is not found as a pure metal in nature. Titanium was first isolated as a pure metal in 1910, but it was not until 1948 that the metal was produced commercially using the Kroll process (named after its developer, William Kroll) to reduce titanium tetrachloride with magnesium to produce titanium metal.

  10. Thermal Stir Welding Development at Marshall Space Flight Center

    NASA Technical Reports Server (NTRS)

    Ding, Robert J.

    2008-01-01

    Solid state welding processes have become the focus of welding process development at NASA's Marshall Space Flight Center. Unlike fusion weld processes such as tungsten inert gas (TIG), variable polarity plasma arc (VPPA), electron beam (EB), etc., solid state welding processes do not melt the material during welding. The resultant microstructure can be characterized as a dynamically recrystallized morphology much different than the casted, dentritic structure typical of fusion weld processes. The primary benefits of solid state processes over fusion weld processes include superior mechanic properties and the elimination of thermal distortion and residual stresses. These solid state processes attributes have profoundly influenced the direction of advanced welding research and development within the NASA agency. Thermal Stir Welding (TSW) is a new solid state welding process being developed at the Marshall Space Flight Center. Unlike friction stir welding, the heating, stirring and forging elements of the weld process can be decoupled for independent control. An induction coil induces energy into a workpiece to attain a desired plastic temperature. An independently controlled stir rod, captured within non-rotating containment plates, then stirs the plasticized material followed by forging plates/rollers that work the stirred weld joint. The independent control (decoupling) of heating, stirring and forging allows, theoretically, for the precision control of microstructure morphology. The TSW process is being used to evaluate the solid state joining of Haynes 230 for ARES J-2X applications. It is also being developed for 500-in (12.5 mm) thick commercially pure grade 2 titanium for navy applications. Other interests include Inconel 718 and stainless steel. This presentation will provide metallurgical and mechanical property data for these high melting temperature alloys.

  11. Thermal Stir Welding Development at Marshall Space Flight Center

    NASA Technical Reports Server (NTRS)

    Ding, Robert J.

    2008-01-01

    Solid state welding processes have become the focus of welding process development at NASA's Marshall Space Flight Center. Unlike fusion weld processes such as tungsten inert gas (TIG), variable polarity plasma arc (VPPA), electron beam (EB), etc., solid state welding processes do not melt the material during welding. The resultant microstructure can be characterized as a dynamically recrystallized morphology much different than the casted, dentritic structure typical of fusion weld processes. The primary benefits of solid state processes over fusion weld processes include superior mechanic properties and the elimination of thermal distortion and residual stresses. These solid state processes attributes have profoundly influenced the direction of advanced welding research and development within the NASA agency. Thermal Stir Welding (TSW) is a new solid state welding process being developed at the Marshall Space Flight Center. Unlike friction stir welding, the heating, stirring and forging elements of the weld process can be decoupled for independent control. An induction coil induces energy into a workpiece to attain a desired plastic temperature. An independently controlled stir rod, captured within non-rotating containment plates, then stirs the plasticized material followed by forging plates/rollers that work the stirred weld joint. The independent control (decoupling) of heating, stirring and forging allows, theoretically, for the precision control of microstructure morphology. The TSW process is being used to evaluate the solid state joining of Haynes 230 for ARES J-2X applications. It is also being developed for 500-in (12.5 mm) thick commercially pure grade 2 titanium for navy applications. Other interests include Inconel 718 and stainless steel. This presentation will provide metallurgical and mechanical property data for these high melting temperature alloys.

  12. Nanopore formation on the surface oxide of commercially pure titanium grade 4 using a pulsed anodization method in sulfuric acid.

    PubMed

    Williamson, R S; Disegi, J; Griggs, J A; Roach, M D

    2013-10-01

    Titanium and its alloys form a thin amorphous protective surface oxide when exposed to an oxygen environment. The properties of this oxide layer are thought to be responsible for titanium and its alloys biocompatibility, chemical inertness, and corrosion resistance. Surface oxide crystallinity and pore size are regarded to be two of the more important properties in establishing successful osseointegration. Anodization is an electrochemical method of surface modification used for colorization marking and improved bioactivity on orthopedic and dental titanium implants. Research on titanium anodization using sulphuric acid has been reported in the literature as being primarily conducted in molarity levels 3 M and less using either galvanostatic or potentiostatic methods. A wide range of pore diameters ranging from a few nanometers up to 10 μm have been shown to form in sulfuric acid electrolytes using the potentiostatic and galvanostatic methods. Nano sized pores have been shown to be beneficial for bone cell attachment and proliferation. The purpose of the present research was to investigate oxide crystallinity and pore formation during titanium anodization using a pulsed DC waveform in a series of sulfuric acid electrolytes ranging from 0.5 to 12 M. Anodizing titanium in increasing sulfuric acid molarities showed a trend of increasing transformations of the amorphous natural forming oxide to the crystalline phases of anatase and rutile. The pulsed DC waveform was shown to produce pores with a size range from ≤0.01 to 1 μm(2). The pore size distributions produced may be beneficial for bone cell attachment and proliferation.

  13. Effects of concentration of Ag nanoparticles on surface structure and in vitro biological responses of oxide layer on pure titanium via plasma electrolytic oxidation

    NASA Astrophysics Data System (ADS)

    Shin, Ki Ryong; Kim, Yeon Sung; Kim, Gye Won; Yang, Hae Woong; Ko, Young Gun; Shin, Dong Hyuk

    2015-08-01

    This study was to investigate how Ag nanoparticles with various concentrations affect the surface structure and in vitro biological properties of oxide layers on the pure titanium produced by a plasma electrolytic oxidation (PEO) process. For this aim, PEO processes were carried out at an AC current density of 100 mA/cm2 for 300 s in potassium pyrophosphate (K4P2O7) electrolytes containing 0, 0.1, 0.3 and 0.5 g/l Ag nanoparticles. Structural investigations using scanning electron microscopy evidenced that the oxide layers showed the successful incorporation of Ag nanoparticles, and the topographical deformation of the porous surface was found when the concentration of Ag nanoparticles was more than 0.1 g/l. Based on the anti-bacterial activity of all oxide layers, the Ag nanoparticles uniformly spread were of considerable importance in triggering the disinfection of E. coli bacteria. The bone forming abilities and cell (MC3T3-E1) proliferation rates of oxide layers produced in electrolytes containing 0 and 0.1 g/l Ag nanoparticles were higher than those containing 0.3 and 0.5 g/l Ag nanoparticles. Consequently, the oxide layer on pure titanium via PEO process in the electrolyte with 0.1 g/l Ag nanoparticles exhibited better the bioactivity accompanying the anti-bacterial activity.

  14. Cracks growth behaviors of commercial pure titanium under nanosecond laser irradiation for formation of nanostructure-covered microstructures (with sub-5-μm)

    NASA Astrophysics Data System (ADS)

    Pan, A. F.; Wang, W. J.; Mei, X. S.; Zheng, B. X.; Yan, Z. X.

    2016-11-01

    This study reported on the formation of sub-5-μm microstructures covered on titanium by cracks growth under 10-ns laser radiation at the wavelength of 532 nm and its induced light modification for production of nanostructures. The electric field intensity and laser power density absorbed by commercial pure titanium were computed to investigate the self-trapping introduced by cracks and the effect of surface morphology on laser propagation characteristics. It is found that nanostructures can form at the surface with the curvature radius below 20 μm. Meanwhile, variable laser fluences were applied to explore the evolution of cracks on commercial pure titanium with or without melt as spot overlap number increased. Experimental study was first performed at the peak laser fluence of 1.063 J/cm2 to investigate the microstructures induced only by cracks growth. The results demonstrated that angular microstructures with size between 1.68 μm and 4.74 μm was obtained and no nanostructure covered. Then, at the peak laser fluence of 2.126 J/cm2, there were some nanostructures covered on the melt-induced curved microstructured surface. However, surface molten material submerged in the most of cracks at the spot overlap number of 744, where the old cracks disappeared. The results indicated that there was too much molten material and melting time at the peak laser fluence of 2.126 J/cm2, which was not suitable for obtainment of perfect micro-nano structures. On this basis, peak laser fluence was reduced down to 1.595 J/cm2 and the sharp sub-5 μm microstructures with nanostructures covered was obtained at spot overlap number of 3720.

  15. Microstructure and Mechanical Properties of Gas-Tungsten-Arc-Welded Ti-15-3 Beta Titanium Alloy

    NASA Astrophysics Data System (ADS)

    Balachandar, K.; Subramanya Sarma, V.; Pant, Bhanu; Phanikumar, G.

    2009-11-01

    Microstructure and mechanical properties of gas-tungsten-arc (GTA)-welded Ti-15V-3Cr-3Sn-3Al alloy in direct current electrode negative mode are characterized. The thermal profile was measured during welding with continuous current (CC) and pulsed current (PC) at different frequencies. A single-step postweld aging of the welded samples at subtransus temperature was attempted to study precipitation of alpha phase. Two different morphologies of alpha phase are observed along with a partitioning of alloying elements into the two phases. Processing conditions for higher strength are identified and correlated with the thermal profile. Microstructure changes due to postweld heat treatment were characterized.

  16. In vitro biological response to the oxide layer in pure titanium formed at different current densities by plasma electrolytic oxidation

    NASA Astrophysics Data System (ADS)

    Shin, Ki Ryong; Kim, Yeon Sung; Yang, Hae Woong; Ko, Young Gun; Shin, Dong Hyuk

    2014-09-01

    This study examined the influence of the current density on the surface characteristics and biological response of titanium oxide layers produced by a plasma electrolytic oxidation process. For this purpose, the present processes were carried out under alternating current conditions in a phosphate electrolyte for 300 s at current densities of 100, 150, 200, and 250 mA/cm2. The pore size decreased with decreasing the current density, whereas the mean surface roughness and amount of anatase phase increased. This tendency is considered suitable for the formation of biomimetic apatite and the proliferation of osteoblast cells. The in vitro examinations showed that the formation of biomimetic apatite and the proliferation of osteoblasts on the titanium oxide layer produced at 100 mA/cm2 were highest among the samples evaluated.

  17. Influence of Helium and Nitrogen Gases on the Properties of Cold Gas Dynamic Sprayed Pure Titanium Coatings

    NASA Astrophysics Data System (ADS)

    Wong, Wilson; Irissou, Eric; Ryabinin, Anatoly N.; Legoux, Jean-Gabriel; Yue, Stephen

    2011-01-01

    This study investigates the effect of propellant gas, helium, and nitrogen during cold spraying of titanium coatings. Coatings were characterized by SEM and were evaluated for their deposition efficiency (DE), microhardness, and porosity. In selected conditions, three particle velocities were investigated in which for each condition, the propelling gases' temperature and pressure were attuned to attain similar particle velocities for each gas. Observations show that loosely bonded particles can be detached by high-pressure supersonic gas stream. Selected coatings were characterized by XPS to analyze the occurrence of oxidation and nitridation. Although generally accepted that coating characteristics can be affected by particle temperature, results show that for the same particle velocity, DE and coating density are also a function of substrate temperature. In addition, a thick and fully dense cold sprayed titanium coating was achieved with optimized spray parameters and nozzle using helium. The corresponding average particle velocity was 1173 m/s.

  18. Feasibility of correlating V-Cr-Ti alloy weld strength with weld chemistry. CRADA final report

    SciTech Connect

    Grossbeck, M.L.; Odom, R.W.

    1998-06-01

    The mechanical properties of refractory metals such as vanadium are determined to a large extent by the interstitial impurities in the alloy. In the case of welding, interstitial impurities are introduced in the welding process from the atmosphere and by dissolution of existing precipitates in the alloy itself. Because of the necessity of having an ultra-pure atmosphere, a vacuum chamber or a glove box is necessary. In the V-Cr-Ti system, the titanium serves as a getter to control the concentration of oxygen and nitrogen in solid solution in the alloy. In this project the secondary ion mass spectrometry (SIMS) technique was used to detect, measure, and map the spacial distribution of impurity elements in welds in the alloy V-4Cr-4Ti. An attempt was then made to correlate the concentrations and distributions of the impurities with mechanical properties of the welds. Mechanical integrity of the welds was determined by Charpy V-notch testing. Welds were prepared by the gas-tungsten-arc (GTA) method. Charpy testing established a correlation between weld impurity concentration and the ductile to brittle transition temperature (DBTT). Higher concentrations of oxygen resulted in a higher DBTT. An exception was noted in the case of a low-oxygen weld which had a high hydrogen concentration resulting in a brittle weld. The concentrations and distributions of the impurities determined by SIMS could not be correlated with the mechanical properties of the welds. This research supports efforts to develop fusion reactor first wall and blanket structural materials.

  19. Size-mediated cytotoxicity of nanocrystalline titanium dioxide, pure and zinc-doped hydroxyapatite nanoparticles in human hepatoma cells

    NASA Astrophysics Data System (ADS)

    Devanand Venkatasubbu, G.; Ramasamy, S.; Avadhani, G. S.; Palanikumar, L.; Kumar, J.

    2012-03-01

    Nanoparticles are highly used in biological applications including nanomedicine. In this present study, the interaction of HepG2 hepatocellular carcinoma cells (HCC) with hydroxyapatite (HAp), zinc-doped hydroxyapatite, and titanium dioxide (TiO2) nanoparticles were investigated. Hydroxyapatite, zinc-doped hydroxyapatite and titanium dioxide nanoparticles were prepared by wet precipitation method. They were subjected to isochronal annealing at different temperatures. Particle morphology and size distribution were characterized by X-ray diffraction and transmission electron microscope. The nanoparticles were co-cultured with HepG2 cells. MTT assay was employed to evaluate the proliferation of tumor cells. The DNA damaging effect of HAp, Zn-doped HAp, and TiO2 nanoparticles in human hepatoma cells (HepG2) were evaluated using DNA fragmentation studies. The results showed that in HepG2 cells, the anti-tumor activity strongly depend on the size of nanoparticles in HCC cells. Cell cycle arrest analysis for HAp, zinc-doped HAp, and TiO2 nanoparticles revealed the influence of HAp, zinc-doped HAp, and titanium dioxide nanoparticles on the apoptosis of HepG2 cells. The results imply that the novel nano nature effect plays an important role in the biomedicinal application of nanoparticles.

  20. High-Powered, Ultrasonically Assisted Thermal Stir Welding

    NASA Technical Reports Server (NTRS)

    Ding, Robert

    2013-01-01

    distance equal to the thickness of the material being welded. The TSW process can be significantly improved by reducing the draw forces. This can be achieved by reducing the friction forces between the weld workpieces and the containment plates. High-power ultrasonic (HPU) vibrations of the containment plates achieve friction reduction in the TSW process. Furthermore, integration of the HPU energy into the TSW stir rod can increase tool life of the stir rod, and can reduce shear forces to which the stir rod is subjected during the welding process. TSW has been used to successfully join 0.500-in (˜13-mm) thick commercially pure (CP) titanium, titanium 6AL- 4V, and titanium 6AL-4V ELI in weld joint lengths up to 9 ft (˜2.75-m) long. In addition, the TSW process was used to fabricate a sub-scale hexagonally shaped gun turret component for the U.S. Navy. The turret is comprised of six 0.5000-in (˜13-mm) thick angled welds. Each angled weld joint was prepared by machining the mating surfaces to 120deg. The angled weld joint was then fixtured using an upper and lower containment plate of the same geometry of the angled weld joint. The weld joint was then stirred by the stir rod as it and the upper and lower containment plates traverse through the angled joint prep.

  1. In-process monitoring and feedback control for stable production of full-penetration weld in continuous wave fibre laser welding

    NASA Astrophysics Data System (ADS)

    Kawahito, Yousuke; Ohnishi, Terumasa; Katayama, Seiji

    2009-04-01

    Laser micro-welding has been applied for device sealing in electronics and automobile industries. Welding of corners in goods and products is a problem owing to easier formation of a weld with burn-through, shallow penetration or a non-bonded part when a drastic change in the welding speed or laser power occurs. This research was therefore undertaken with the objective of obtaining a fundamental knowledge of in-process monitoring and feedback control for the stable production of a full-penetration weld with a constant bead width on the bottom surface irrespective of the changes in the laser power and the welding speed. Variation in weld penetration geometry was investigated by rapid deceleration and acceleration in the welding speed during lap welding of pure titanium thin sheets with a continuous wave (CW) single-mode fibre laser beam. The rapid deceleration in the welding speed led to a considerable change in the full-penetration weld geometry or a partially penetrated weld (if the power was accordingly reduced), resulting in the difficulty in the stable production of a full-penetration weld bead. The heat radiation intensity measured from the laser-irradiated area was useful as an in-process monitoring signal for detecting the molten pool size on the laser-irradiated surface. However, the utilization of monitoring of heat radiation was difficult for predicting the weld bead width on the bottom surface due to the formation of partial penetration or the change in the penetration shape. The laser power was controlled at a 4 ms interval according to the heat radiation signal in order to adjust the weld bead width on the laser-irradiated surface to the target weld penetration geometry affected by thermal storage. Consequently, the feedback-controlled laser power produced a stable full-penetration weld with the designed bead width on the bottom surface irrespective of the rapid deceleration of the welding speed and the corresponding decrease in laser power

  2. Proliferation of mouse fibroblast-like and osteoblast-like cells on pure titanium films manufactured by electron beam melting.

    PubMed

    Kawase, Mayu; Hayashi, Tatsuhide; Asakura, Masaki; Tomino, Masafumi; Mieki, Akimichi; Kawai, Tatsushi

    2016-10-01

    The physical characteristics and biological compatibility of surfaces produced by electron beam melting (EBM) are not well known. In particular, there are not many reports on biocompatibility qualities. In this study, pure Ti films were manufactured using EBM. While it is reported that moderately hydrophilic biomaterial surfaces display improved cell growth and biocompatibility, contact angle measurements on the EBM-produced pure Ti films showed slight hydrophobicity. Nonetheless, we found the cell count of both fibroblast-like cells (L929) and osteoblast-like cells (MC3T3-E1) increased on pure Ti films, especially the MC3T3-E1, which increased more than that of the control. In addition, the morphology of L929 and MC3T3-E1 was polygonal and spindle-shaped and the cytoskeleton was well developed in the pure Ti surface groups. Upon staining with Alizarin red S, a slight calcium deposition was observed and this level gradually rose to a remarkable level. These results indicate that pure Ti films manufactured by EBM have good biocompatibility and could be widely applied as biomedical materials in the near future.

  3. Interaction of human plasma fibrinogen with commercially pure titanium as studied with atomic force microscopy and X-ray photoelectron spectroscopy.

    PubMed

    Keere, Isabel Van De; Willaert, Ronnie; Hubin, Annick; Vereecken, Jean

    2008-03-04

    The surface of a biomaterial interacts with the body fluid upon implantation in the human body. The biocompatibility of a material is strongly influenced by the adsorption of proteins onto the surface. Titanium is frequently used as a biomaterial for implants in orthopedics and cardiovascular devices. Understanding the biocompatibility is very important to improve implants. The surface chemistry of an implant material and its influence on the interaction with body fluid is crucial in that perspective. The main goal of this study was to investigate the conformation of human plasma fibrinogen (HPF) adsorbed on commercially pure titanium (CP Ti) on a molecular level by means of ex situ atomic force microscopy (AFM). With X-ray photoelectron spectroscopy combined with argon ion beam depth profiling, it was shown that the oxide layer present at the surface was mainly composed of TiO2, with a small percentage of Ti2O3. Ex situ AFM imaging showed the conformation of HPF on CP Ti. Single molecules and aggregates of fibrinogen were observed. The trinodular structure of single HPF molecules (two spherical D domains at the distal ends of the extended molecule and the central spherical E domain) adsorbed onto CP Ti was visualized. Aggregate formation through the connection of the D domains of the HPF molecules was observed on CP Ti. The alphaC domains of HPF were not visible on CP Ti. The ex situ AFM images indicated conformational changes of HPF upon adsorption onto CP Ti. The conformation of the adsorbed HPF molecules was different on mica and titanium. The difference in wettability between both substrates caused a larger spread of the protein on the CP Ti surface and thus resulted in a larger perturbation to the native structure of HPF as compared to mica.

  4. Effect of laser beam offset on microstructure and mechanical properties of pulsed laser welded BTi-6431S/TA15 dissimilar titanium alloys

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Hu, Shengsun; Shen, Junqi; Li, Dalong; Bu, Xianzheng

    2015-11-01

    Laser beam welding was used to weld dissimilar joints in BTi-6431S/TA15 titanium alloys. The effect of laser beam offset on microstructural characterizations and mechanical properties of the joints were investigated. Microstructural evolution of the joints was characterized by optical microscopy (OM) and X-ray diffraction (XRD). Tensile testing was conducted at room temperature and at 550 °C. The results demonstrated that with the exception of some porosity, a good quality joint could be achieved. Martensite α' and acicular α structures were present in the fusion zone (FZ). The amount of martensite α' present with the -0.2 mm beam offset was less than that with the 0.2 mm beam offset. Acicular α and martensite α' transformations occurred in the high temperature heat-affected zone (HT-HAZ) of both the BTi-6431S and TA15 alloys. In the low-temperature heat-affected zone (LT-HAZ), the BTi-6431S and TA15 alloy microstructures exhibited a mixture of secondary α, primary α, and prior β phases. The microhardness values in the FZ followed the order: -0.2 mm> 0 mm> 0.2 mm. Tensile testing at room temperature and at 550 °C resulted in fracture of the TA15 alloy base metal. The fracture morphology exhibited a ductile dimple feature.

  5. Synthesis by anodic-spark deposition of Ca- and P-containing films on pure titanium and their biological response

    NASA Astrophysics Data System (ADS)

    Banakh, Oksana; Journot, Tony; Gay, Pierre-Antoine; Matthey, Joël; Csefalvay, Catherine; Kalinichenko, Oleg; Sereda, Olha; Moussa, Mira; Durual, Stéphane; Snizhko, Lyubov

    2016-08-01

    The purpose of this work is to characterize the anodized layers formed on titanium by anodic-spark deposition in an electrolyte containing Ca and P ions, Ca3(PO4)2, studied for the first time. The oxidation experiments were performed at different periods of time and using different concentrations of electrolyte. The influence of the process parameters (time of electrolysis and electrolyte concentration) on the surface morphology and chemical composition of the anodized layers was studied. It has been found that it is possible to incorporate Ca and P into the growing layer. A response of the anodized layers in a biological medium was evaluated by their immersion in a simulated body fluid. An enrichment of titanium and a simultaneous loss of calcium and phosphorus in the layer after immersion tests indicate that these coatings should be bioresorbable in a biological medium. Preliminary biological assays were performed on some anodized layers in order to assess their biocompatibility with osteoblast cells. The cell proliferation on one selected anodized sample was assessed up to 21 days after seeding. The preliminary results suggest excellent biocompatibility properties of anodized coatings.

  6. Structures and properties of layered bioceramic coatings on pure titanium using a hybrid technique of sandblasting and micro-arc oxidation

    NASA Astrophysics Data System (ADS)

    Wang, Hong-Yuan; Zhu, Rui-Fu; Lu, Yu-Peng; Xiao, Gui-Yong; Ma, Xiao-Ni; Li, Ying

    2013-10-01

    Sandblasting is the most ordinary approach not only to leave the treated regions in compressive residual stress states but also to alter the surface topography of an implant, and micro-arc oxidation (MAO) provides a novelly effective way to produce porous, adhesive and bioactive implant coatings. In this study, ceramic coatings containing Ca and P elements were deposited on the sandblasted pure titanium substrates through the MAO process, and the bioactive performance of the coatings was improved. In addition, the variation of morphology and microstructure, phase and element composition of the coatings according to treating time and related properties were characterized and analyzed, respectively. It was indicated that the hybrid-treated coatings exhibited better properties than that by MAO method, especially in hydroxyapatite (HA) inducing ability, as evidenced by characterization test and HA formation after simulated body fluid (SBF) immersion for days. The enhancement of modified surface was attributed to the combination of the physical and electrochemical treatments.

  7. Effect of Multi-pass Friction Stir Processing on the Electrochemical and Corrosion Behavior of Pure Titanium in Strongly Acidic Solutions

    NASA Astrophysics Data System (ADS)

    Fattah-Alhosseini, Arash; Attarzadeh, Farid Reza; Vakili-Azghandi, Mojtaba

    2017-01-01

    The corrosion behavior of multi-pass friction stir processed (FSP) pure titanium was studied in 0.5 M H2SO4 solutions. Microstructures of treated and untreated samples were characterized using scanning electron microscopy. It was found that the grain size decreased with increasing the number of applied passes of FSP. Electrochemical tests including potentiodynamic polarization measurements and electrochemical impedance spectroscopy showed that three passes of FSP treatments resulted in a Ti sample which exhibited the best passive behavior and had the highest corrosion resistance among all samples in strongly acidic solutions of 0.5 M H2SO4. These improvements can be attributed to the emergence of diverse structural defects and grain refinement induced by FSP treatments. Moreover, Mott-Schottky analysis was performed to investigate the semiconducting properties of passive films. It was found that the semiconducting behavior remained the same after FSP treatments but it reduced donor densities and surprisingly introduced an additional donor level.

  8. Role of surface roughness on corrosion and fretting corrosion behaviour of commercially pure titanium in Ringer's solution for bio-implant application

    NASA Astrophysics Data System (ADS)

    Sivakumar, Bose; Pathak, Lokesh Chandra; Singh, Raghuvir

    2017-04-01

    Influence of roughness (ra) from 43 to 474 nm on corrosion and fretting corrosion of commercially pure titanium (CpTi) was studied in the Ringer's solution. The anodic polarization and electrochemical impedance spectroscopy (EIS) revealed the highest corrosion resistance of CpTi with ra 43 nm and correlated well with the surface energy (SE). The highest potential drop associated with the fretting corrosion is observed for CpTi with ra 43 nm followed by 474 nm; this is found to correspond with the worn out area. The fretting current density (ifretting) is several order higher than obtained during the potentiodynamic polarization (without fretting) study. Fretting corrosion manifested by the drop in electrochemical potential is simulated with high accuracy using fretting current density and an initial contact area. Fretting corrosion at an applied potential (+250 mV(SCE)) is produced much larger fretting corrosion current density than during the open circuit potential (OCP).

  9. Effect of sandblasting intensity on microstructures and properties of pure titanium micro-arc oxidation coatings in an optimized composite technique

    NASA Astrophysics Data System (ADS)

    Wang, Hong-Yuan; Zhu, Rui-Fu; Lu, Yu-Peng; Xiao, Gui-Yong; He, Kun; Yuan, Y. F.; Ma, Xiao-Ni; Li, Ying

    2014-02-01

    Sandblasting is one of the most effective methods to modify a metal surface and improve its properties for application. Micro-arc oxidation (MAO) could produce a ceramic coating on a dental implant, facilitating cellular differentiation and osseocomposite on it. This study aims to deposit bioceramic Ca- and P-containing coatings on sandblasted commercially pure titanium by an optimum composite technique to improve the bioactive performance. The effect of sandblasting intensity on microstructures and properties of the implant coatings is examined, and the modified surfaces are characterized in terms of their topography, phase, chemical composition, mechanical properties and hydroxyapatite (HA)-inducing ability. The results show that a moderate sandblasting micromachines the substrate in favorable combination of rough and residual stresses; its MAO coating deposits nano-hydroxyapatite after immersion in simulated body fluid (SBF) for 5 days exhibiting better bioactivity. The further improvement of the implant surface performance is attributed to an optimized composite technique.

  10. Comparative evaluation of the three different surface treatments - conventional, laser and Nano technology methods in enhancing the surface characteristics of commercially pure titanium discs and their effects on cell adhesion: An in vitro study.

    PubMed

    Vignesh; Nayar, Sanjna; Bhuminathan; Mahadevan; Santhosh, S

    2015-04-01

    The surface area of the titanium dental implant materials can be increased by surface treatments without altering their shape and form, thereby increasing the biologic properties of the biomaterial. A good biomaterial helps in early cell adhesion and cell signaling. In this study, the commercially pure titanium surfaces were prepared to enable machined surfaces to form a control material and to be compared with sandblasted and acid-etched surfaces, laser treated surfaces and titanium dioxide (20 nm) Nano-particle coated surfaces. The surface elements were characterized. The biocompatibility was evaluated by cell culture in vitro using L929 fibroblasts. The results suggested that the titanium dioxide Nano-particle coated surfaces had good osteoconductivity and can be used as a potential method for coating the biomaterial.

  11. Comparative evaluation of the three different surface treatments – conventional, laser and Nano technology methods in enhancing the surface characteristics of commercially pure titanium discs and their effects on cell adhesion: An in vitro study

    PubMed Central

    Vignesh; Nayar, Sanjna; Bhuminathan; Mahadevan; Santhosh, S.

    2015-01-01

    The surface area of the titanium dental implant materials can be increased by surface treatments without altering their shape and form, thereby increasing the biologic properties of the biomaterial. A good biomaterial helps in early cell adhesion and cell signaling. In this study, the commercially pure titanium surfaces were prepared to enable machined surfaces to form a control material and to be compared with sandblasted and acid-etched surfaces, laser treated surfaces and titanium dioxide (20 nm) Nano-particle coated surfaces. The surface elements were characterized. The biocompatibility was evaluated by cell culture in vitro using L929 fibroblasts. The results suggested that the titanium dioxide Nano-particle coated surfaces had good osteoconductivity and can be used as a potential method for coating the biomaterial. PMID:26015762

  12. Pure titanium particle loaded nanocomposites: study on the polymer/filler interface and hMSC biocompatibility.

    PubMed

    Avolio, Roberto; D'Albore, Marietta; Guarino, Vincenzo; Gentile, Gennaro; Cocca, Maria Cristina; Zeppetelli, Stefania; Errico, Maria Emanuela; Avella, Maurizio; Ambrosio, Luigi

    2016-10-01

    The integration of inorganic nanoparticles into polymer matrices allows for the modification of physical properties as well as the implementation of new features for unexplored application fields. Here, we propose the study of a new metal/polymer nanocomposite fabricated by dispersing pure Ti nanoparticles into a poly(methylmetacrilate) matrix via solvent casting process, to investigate its potential use as new biomaterial for biomedical applications. We demonstrated that Ti nanoparticles embedded in the poly(methylmetacrilate) matrix can act as reinforcing agent, not negatively influencing the biological response of human mesenchymal stem cell in terms of cytotoxicity and cell viability. As a function of relative amount and surface treatment, Ti nanoparticles may enhance mechanical strength of the composite-ranging from 31.1 ± 2.5 to 43.7 ± 0.7 MPa-also contributing to biological response in terms of adhesion and proliferation mechanisms. In particular, for 1 wt% Ti, treated Ti nanoparticles improve cell materials recognition, as confirmed by higher cell spreading-quantified in terms of cell area via image analysis-locally promoting stronger interactions at cell matrix interface. At this stage, these preliminary results suggest a promising use of pure Ti nanoparticles as filler in polymer composites for biomedical applications.

  13. The effect of scanning electrochemical potential on the short-term impedance of commercially pure titanium in simulated biological conditions.

    PubMed

    Ehrensberger, Mark T; Gilbert, Jeremy L

    2010-09-01

    The electrochemical history (voltage-time variations) of titanium oxide-solution interfaces can vary widely in vivo, particularly where oxide abrasion is present, and it is important to assess the effects of voltage on the impedance behavior of the interface. Potential step impedance analysis (PSIA) utilizes a time and frequency domain methodology to assess the electrochemical impedance of electrified interfaces over a range of voltages. The PSIA method was used to study the combined effects of scanning electrical potential and the presence of solution-born organic species (protein, amino acids, etc.) on the electrochemical properties of cpTi. The specific solutions used in these scanning PSIA experiments were phosphate buffered saline and cell culture medium supplemented with 10% fetal bovine serum. The results show that electrochemical impedance properties of cpTi are voltage-time history dependent and strongly influenced by electrical potential within the -1000 mV to +1000 mV range studied. Moreover, the presence of biologically relevant molecules in the electrolyte solution alters the impedance properties only at cathodic potentials. Specifically, at cathodic potentials, these organic species have been shown to suppress the cathodic current density, shift the zero current potential in the cathodic direction, and increase the interfacial capacitance, polarization resistance, and the distribution of surface relaxation times. At anodic potentials, the presence of the organic species does not alter any of the electrochemical properties examined. Overall, these results show the importance of understanding of the variation in electrochemical potentials achievable in vivo and the effects voltage history has on interfacial electrochemical behavior. (c) 2010 Wiley Periodicals, Inc.

  14. Pure Titanium Membrane (Ultra – Ti®) in the Treatment of Periodontal Osseous Defects: A Split-Mouth Comparative Study

    PubMed Central

    Khanna, Rajeev; Pardhe, Nilesh Dinesh; Srivastava, Nancy; Bajpai, Manas; Gupta, Shailendra

    2016-01-01

    Introduction Although many different types of Guided Tissue Regeneration (GTR) membranes (resorbable/non-resorbable, including titanium mesh) have been used in the field of Periodontics till now, but this is the first and only clinical study testing the effectiveness of an ultra thin pure Titanium Membrane (Ultra Ti) as a GTR membrane in infra-bony periodontal defects. Aim To compare the efficacy of GTR in intra-bony defects with newly introduced non-resorbable barrier membrane, made of titanium called “Ultra-Ti ® GTR Membrane” versus open flap debridement. Materials and Methods A prospective, randomized, controlled, clinical split mouth study was designed wherein each patient received both the control and test treatment. Two similar defects were selected in each of the 12 patients and were randomly assigned to one of the two treatments. Both the surgeries consisted of identical procedures except for the omission of the barrier membrane in the control sites. Full mouth Plaque Index (PI), Gingival Index (GI), Pocket Probing Depth (PPD) and Relative Attachment Level (RAL) were recorded before surgery and after 6 months and 9 months along with hard tissue measurements at the time of surgery and then at re-entry after 9 months. Radiographs were also taken before surgery and 9 months post operatively. Student’s paired t-test and unpaired t-test (SPSS software version 9) were used to analyze the results. Results Nine months after treatment, the test defects gained 4.375 ± 1.189mm of RAL, while the control defects yielded a significantly lower RAL gain of 3.417 ± 0.996mm. Pocket reduction was also significantly higher in the test group (4.917 ± 0.996mm) when compared with the controls (3.83 ± 0.718mm). There was a significant bone fill (54.69% of defect fill) obtained in the test site, unlike the control site (8.91%). Conclusion The present study demonstrated that GTR with “Ultra-Ti® GTR Membrane” resulted in a significant added benefit in comparison with

  15. Hot press and roll welding of titanium-6-percent-aluminum-4-percent-vanadium bar and sheet with auto-vacuum cleaning

    NASA Technical Reports Server (NTRS)

    Holko, K. H.

    1972-01-01

    Hot press butt welds were made in 0.5 in. diameter bar, and roll lap welds were made in 0.060 in. thick sheet of Ti-6A1-4V. For hot press welds made after auto-vacuum cleaning at 1800 F for 2 hours, weld strength and ductility equaled the parent metal properties. Only 5 minutes of pressing time were needed at 1800 F and 200 psi to make the hot press welds. Roll welds were made in sheet at 1750 F with only 10 percent deformation. The welds in the bar and sheet were metallurgically indistinguishable from the parent material.

  16. Microstructure and Oxidation Behavior of Al and Al/NiCrAlY Coatings on Pure Titanium Alloy

    NASA Astrophysics Data System (ADS)

    Gong, Xue; Zhang, Nannan; Zhang, Zhongli; Chen, Ruirun; Lin, Danyang

    2017-06-01

    To improve the oxidation resistance of Ti alloys, a NiCrAlY coating was deposited as diffusion barrier between aluminum overlay coating and pure Ti substrate by air plasma spraying method. The microstructure and oxidation behavior of Al coatings with and without NiCrAlY diffusion barrier were investigated in isothermal oxidation tests at 800 °C for 100 h. The results indicate that the weight gain of the Al/NiCrAlY coating was 4.16 × 10-5 mg2 cm-4 s-1, whereas that of the single Al coating was 9.52 × 10-5 mg2 cm-4 s-1 after 100 h oxidation. As compared with single Al coating, the Al/NiCrAlY coating revealed lower oxidation rate and excellent oxidation resistance by forming thin Al2O3 + NiO scales at overlaying coating/diffusion barrier and diffusion barrier/substrate interfaces. Meanwhile, the inward diffusion of Al and the outward diffusion of Ti were inhibited effectively by the NiCrAlY diffusion barrier.

  17. In vitro evaluation of cytotoxicity and corrosion behavior of commercially pure titanium and Ti-6Al-4V alloy for dental implants.

    PubMed

    Chandar, Sanchitha; Kotian, Ravindra; Madhyastha, Prashanthi; Kabekkodu, Shama Prasada; Rao, Padmalatha

    2017-01-01

    The aim of this study was to investigate the cytotoxicity in human gingival fibroblast by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and corrosion behavior by potentiodynamic polarization technique of commercially pure titanium (Ti 12) and its alloy Ti-6Al-4V (Ti 31). In the present in vitro study, cytotoxicity of Ti 12 and Ti 31 in human gingival fibroblast by MTT assay and the corrosion behavior by potentiodynamic polarization technique in aqueous solutions of 0.1 N NaCl, 0.1 N KCl, and artificial saliva with and without NaF were studied. The independent t-test within materials and paired t-test with time interval showed higher cell viability for Ti 12 compared to Ti 31. Over a period, cell viability found to stabilize in both Ti 12 and Ti 31. The effects of ions of Ti and alloying elements aluminum and vanadium on the cell viability were found with incubation period of cells on samples to 72 h. The electrochemical behavior of Ti 12 and Ti 31 in different experimental solutions showed a general tendency for the immersion potential to shift steadily toward nobler values indicated formation of TiO2 and additional metal oxides. The multiphase alloy Ti-6Al-4V showed more surface pitting. The commercially pure Ti showed better cell viability compared to Ti 31. Less cell viability in Ti 31 is because of the presence of aluminum and vanadium. A significant decrease in cytotoxicity due to the formation of TiO2 over a period of time was observed both in Ti 12 and Ti 31. The electrochemical behavior of Ti 12 and Ti 31 in different experimental solutions showed a general tendency for the immersion potential to shift steadily toward nobler values indicated formation of TiO2 and additional metal oxides. Ti 31 alloy showed surface pitting because of its multiphase structure.

  18. Ultrasonic Stir Welding

    NASA Technical Reports Server (NTRS)

    Nabors, Sammy

    2015-01-01

    NASA Marshall Space Flight Center (MSFC) developed Ultrasonic Stir Welding (USW) to join large pieces of very high-strength metals such as titanium and Inconel. USW, a solid-state weld process, improves current thermal stir welding processes by adding high-power ultrasonic (HPU) energy at 20 kHz frequency. The addition of ultrasonic energy significantly reduces axial, frictional, and shear forces; increases travel rates; and reduces wear on the stir rod, which results in extended stir rod life. The USW process decouples the heating, stirring, and forging elements found in the friction stir welding process allowing for independent control of each process element and, ultimately, greater process control and repeatability. Because of the independent control of USW process elements, closed-loop temperature control can be integrated into the system so that a constant weld nugget temperature can be maintained during welding.

  19. Nanostructure of vortex during explosion welding.

    PubMed

    Rybin, V V; Greenberg, B A; Ivanov, M A; Patselov, A M; Antonova, O V; Elkina, O A; Inozemtsev, A V; Salishchev, G A

    2011-10-01

    The microstructure of a bimetallic joint made by explosion welding of orthorhombic titanium aluminide (Ti-30Al-16Nb-1Zr-1Mo) with commercially pure titanium is studied. It is found that the welded joint has a multilayered structure including a severely deformed zone observed in both materials, a recrystallized zone of titanium, and a transition zone near the interface. Typical elements of the transition zone-a wavy interface, macrorotations of the lattice, vortices and tracks of fragments of the initial materials-are determined. It is shown that the observed vortices are formed most probably due to local melting of the material near the contact surface. Evidence for this assumption is deduced from the presence of dipoles, which consist of two vortices of different helicity and an ultrafine duplex structure of the vortex. Also, high mixing of the material near the vortex is only possible by the turbulent transport whose coefficient is several orders of magnitude larger than the coefficient of atomic diffusion in liquids. The role played by fragmentation in both the formation of lattice macrorotations and the passage of coarse particles of one material through the bulk of the other is determined.

  20. The Impact of Force Transmission on Narrow-Body Dental Implants Made of Commercially Pure Titanium and Titanium Zirconia Alloy with a Conical Implant-Abutment Connection: An Experimental Pilot Study.

    PubMed

    Nelson, Katja; Schmelzeisen, Rainer; Taylor, Thomas D; Zabler, Simon; Wiest, Wolfram; Fretwurst, Tobias

    2016-01-01

    The purpose of this study was to visualize the mode and impact of force transmission in narrowdiameter implants with different implant-abutment designs and material properties and to quantify the displacement of the abutment. Narrow-diameter implants from two manufacturers were examined: Astra 3.0-mm-diameter implants (Astra OsseoSpeed TX; n = 2) and Straumann Bone Level implants with a 3.3-mm diameter made of commercially pure titanium (cpTi) Gr. 4 (n = 2) and 3.3-mm TiZr-alloy (n = 2; Bone Level, Straumann) under incremental force application using synchrotron radiography (absorption and inline x-ray phase-contrast) and tomography. During loading (250 N), Astra 3.0 and Bone Level 3.3- mm implants showed a deformation of the outer implant shoulder of 61.75 to 95 μm independent of the implant body material; the inner implant diameter showed a deformation of 71.25 to 109.25 μm. A deformation of the implant shoulder persisted after the removal of the load (range, 42.75 to 104.5 μm). An angulated intrusion of the abutment (maximum, 140 μm) into the implant body during load application was demonstrated; this spatial displacement persisted after removal of the load. This study demonstrated a deformation of the implant shoulder and displacement of the abutment during load application in narrow-diameter implants.

  1. Effect of pressure of helium, argon, krypton, and xenon on the porosity, microstructure, and mechanical properties of commercially pure titanium castings.

    PubMed

    Zinelis, S

    2000-11-01

    Porosity is a frequently observed casting defect in dental titanium alloys. This study evaluated the effect of pressure of helium, argon, krypton, and xenon on the porosity, microstructure, and mechanical properties of commercially pure titanium (cp Ti) castings. Eight groups (A-H) of 16 rectangular wax patterns each (30 mm in length, 3 mm in width, and 1 mm in depth) were prepared. The wax patterns were invested with a magnesia-based material and cast with cp Ti (grade II). Groups A, C, E, and G were cast under a pressure of 1 atm, and groups B, D, F, and H were cast under a pressure of 0.5 atm of He, Ar, Kr, and Xe, respectively. The extent of the porosity of the cast specimens was determined radiographically and quantified by image analysis. Three specimens of each group and 3 cylinders of the as-received cp Ti used as a reference were embedded in resin and studied metallographically after grinding, polishing, and chemical etching. These surfaces were used for determination of the Vickers hardness (VHN) as well. Eight specimens from each group were fractured in the tensile mode, and the 0.2% yield strength, fracture stress, and percentage elongation were calculated. Porosity was analyzed with 2-way ANOVA and the Newman-Keuls multiple range test. VHN measurements and tensile properties for specimen groups were compared with 1-way ANOVA and the Newman-Keuls multiple range test (95% significance level). The porosity levels per group were (%): A = 5.50 +/- 4.34, B = 0.77 +/- 1.27, C = 2.44 +/- 3.68, D = 0.06 +/- 0.12, E-H = 0. Two-way ANOVA showed that there was no detectable interaction (P<.05) between gas type and applied pressure. Metallographic examination revealed no differences in microstructure among the groups studied. A finer grain size was observed in all cast groups compared with the original cp Ti. The VHN of the as-received cp Ti was significantly greater than all the cast groups tested. Groups cast under He showed the highest VHN, yield strength, and

  2. Technique development for field inspection of cracking in seam welded ducts

    SciTech Connect

    Shell, Eric B.; Benson, Craig; Liljestrom, Greg C.; Shanahan, Stephen

    2014-02-18

    The resistance seam weld interfaces between alloyed and pure titanium are an in service concern due to precipitation of titanium hydride and resulting embrittlement and cracking. Several inspection techniques were developed and evaluated for field use to characterize the damage in the fleet. Electromagnetic, ultrasonic, florescent penetrant, thermographic, and radiographic techniques were considered. The ultrasonic and electromagnetic approaches were both found suitable. However, the electromagnetic approach is more desirable for field inspections, due to consistency and ease of use. The electromagnetic inspection procedure is able to discriminate between precursor damage and through cracking with sufficient sensitivity to small cracks.

  3. Bonding titanium to Rene 41 alloy

    NASA Technical Reports Server (NTRS)

    Scott, R. W.

    1972-01-01

    Pair of intermediate materials joined by electron beam welding method welds titanium to Rene 41 alloy. Bond is necessary for combining into one structure high strength-to-density ratio titanium fan blades and temperature resistant nickel-base alloy turbine-buckets in VTOL aircraft lift-fan rotor.

  4. Parametric study in weld mismatch of longitudinally welded SSME HPFTP inlet

    NASA Technical Reports Server (NTRS)

    Min, J. B.; Spanyer, K. L.; Brunair, R. M.

    1991-01-01

    Welded joints are an essential part of pressure vessels such as the Space Shuttle Main Engine (SSME) Turbopumps. Defects produced in the welding process can be detrimental to weld performance. Recently, review of the SSME high pressure fuel turbopump (HPFTP) titanium inlet x rays revealed several weld discrepancies such as penetrameter density issues, film processing discrepancies, weld width discrepancies, porosity, lack of fusion, and weld offsets. Currently, the sensitivity of welded structures to defects is of concern. From a fatigue standpoint, weld offset may have a serious effect since local yielding, in general, aggravates cyclic stress effects. Therefore, the weld offset issue is considered. Using the finite element method and mathematical formulations, parametric studies were conducted to determine the influence of weld offsets and a variation of weld widths in longitudinally welded cylindrical structures with equal wall thickness on both sides of the joint. From the study, the finite element results and theoretical solutions are presented.

  5. Remote welding equipment for TPX

    SciTech Connect

    Silke, G.W.; Junge, R.

    1995-12-31

    Remote welding equipment and techniques are necessary for maintenance of the Tokamak Physics Experiment (TPX) Plasma Facing Components (PFCs). The processes identified for this application includes inside diameter (i.d.) and outside diameter (o.d.) Gas Tungsten Arc (GTA) welding of titanium and stainless steel alloys. Welding equipment developed for this application includes some unique features due to the specialized environment of the TPX vessel. Remote features of this equipment must include the ability to acquire and align the parts being welded, perform all welding operations and visually inspect the weld area. Designs for weld heads require the integration of industry proven hardware with the special features include compact size, remote manipulation, remote clamping and alignment, remote vision, full inert gas coverage, arc voltage control, wire feed, programmable weld schedules and failure recovery.

  6. Improvement to the marginal coping fit of commercially pure titanium cast in phosphate-bonded investment by using a simple pattern coating technique.

    PubMed

    Pieralini, Anelise Rodolfo Ferreira; Nogueira, Fabiane; Ribeiro, Ricardo Faria; Adabo, Gelson Luis

    2012-07-01

    Coatings of zirconite, Y(2)O(3) or ZrO(2) on wax patterns before investing in phosphate-bonded investments have been recommended to reduce the reaction layer in titanium castings, but they are not easily obtainable. Spinel-based investments are relatively stable with molten titanium and could be used as coatings to improve the quality of castings made with those investments. The purpose of this study was to evaluate the effect of pattern coating with a commercial spinel-based investment before investing in 1 of 3 phosphate-bonded inves tments on the marginal coping fit and surface roughness of commercially pure titanium castings. Ten square acrylic resin patterns (12 × 12 × 2 mm) per group were invested in the phosphate-bonded investments Rematitan Plus (RP), Rema Exakt (RE), and Castorit Super C (CA) with or without a coating of the spinel-based investment, Rematitan Ultra (RU). After casting, the specimens were cleaned and the surface roughness was measured with a profilometer. Copings for dental implants with conical abutment were invested, eliminated, and cast as previously described. The copings were cleaned and misfit was measured with a profile projector (n=10). For both tests, the difference between the mean value of RU only and each value of the phosphate-bonded investment was calculated, and the data were analyzed by 2-way ANOVA and Tukey's HSD test (α=.05). In addition, the investment roughness was measured in bar specimens (30 × 10 × 10 mm), and the data (n=10) were analyzed by 1-way ANOVA and Tukey's HSD post hoc test (α=.05). Two-way ANOVA for casting surface roughness was significant because of the investment, the coating technique, and the interaction between variables. One-way ANOVA was performed to prove the interaction term, and Tukey's post hoc test showed that RP with coating had the lowest mean, while RP had the highest. CA with coating was not different from RP with coating or CA without coating. RE with coating was similar to CA, while

  7. New explosive seam welding concepts

    NASA Technical Reports Server (NTRS)

    Bement, L. J.

    1973-01-01

    Recently developed techniques provide totally-confined linear explosive seam welding and produce scarf joint with linear explosive seam welding. Linear ribbon explosives are utilized in making narrow, continuous, airtight joints in variety of aluminum alloys, titanium, copper, brass, and stainless steel.

  8. Effects of the nanotopographic surface structure of commercially pure titanium following anodization-hydrothermal treatment on gene expression and adhesion in gingival epithelial cells.

    PubMed

    Takebe, J; Miyata, K; Miura, S; Ito, S

    2014-09-01

    The long-term stability and maintenance of endosseous implants with anodized-hydrothermally treated commercially pure titanium surfaces and a nanotopographic structure (SA-treated c.p.Ti) depend on the barrier function provided by the interface between the transmucosal portion of the implant surface and the peri-implant epithelium. This study investigated the effects of extracellular and intracellular gene expression in adherent gingival epithelial cells cultured for 1-7 days on SA-treated c.p.Ti implant surfaces compared to anodic oxide (AO) c.p.Ti and c.p.Ti disks. Scanning electron microscopy (SEM) showed filopodium-like extensions bound closely to the nanotopographic structure of SA-treated c.p.Ti at day 7 of culture. Gene expressions of focal adhesion kinase, integrin-α6β4, and laminin-5 (α3, β3, γ2) were significantly higher on SA-treated c.p.Ti than on c.p.Ti or AO c.p.Ti after 7 days (P<0.05). Our results confirmed that gingival epithelial cells adhere to SA-treated c.p.Ti as the transmucosal portion of an implant, and that this interaction markedly improves expression of focal adhesion molecules and enhances the epithelial cell phenotype. The cellular gene expression responses driving extracellular and intracellular molecular interactions thus play an important role in maintenance at the interface between SA-treated c.p.Ti implant surfaces and the gingival epithelial cells. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Modification of the structure and properties of commercially pure titanium through nitriding and subsequent TiN coating deposition in a single vacuum cycle

    NASA Astrophysics Data System (ADS)

    Ivanov, Yu F.; Krysina, O. V.; Petrikova, E. A.; Shugurov, V. V.; Tolkachev, O. S.; Teresov, A. D.; Koval, N. N.

    2017-05-01

    The modification of titanium by ion plasma methods consisting of hard coatings deposition on a specimen surface subjected to nitriding is carried out. It is shown that complex modification of the titanium in a single vacuum cycle is followed by formation of multilayered multiphase structure which tribological properties multiply exceed the corresponding properties of the material treated on two vacuum separated setups.

  10. Three-dimensional distortion of gold alloy castings and welded titanium frameworks. Measurements of the precision of fit between completed implant prostheses and the master casts in routine edentulous situations.

    PubMed

    Jemt, T

    1995-08-01

    Thirty routine patients, provided with fixed prostheses supported by osseointegrated Brånemark implants in edentulous lower jaws, were arranged into three different groups with regard to design of the metal framework. Ten patients received cast gold alloy frames and the other two groups were provided with two different designs of welded titanium frames. The fit of the completed prostheses was measured in three dimensions (3-D) in relation to the master cast, by means of a photogrammetric technique, prior to insertion. Mean 3-D distortion of the centre point of the gold cylinder was 42 (s.d. 8) microns for the cast framework. The corresponding mean distortion for the two designs of titanium frameworks was 43 (s.d. 16) and 36 (s.d. 10) microns, respectively. Least distortion was observed in vertical direction for all three designs. None of the different designs of metal frames showed a significantly better fit (P > 0.05), but the cast and oldest titanium framework design presented a much wider range of distortion. This indicated a higher risk of sectioning and resoldering during the fabrication of the prostheses as compared to the more consistently fabricated prostheses, with a new titanium framework design.

  11. Failure behavior of plasma-sprayed HAp coating on commercially pure titanium substrate in simulated body fluid (SBF) under bending load.

    PubMed

    Laonapakul, Teerawat; Rakngarm Nimkerdphol, Achariya; Otsuka, Yuichi; Mutoh, Yoshiharu

    2012-11-01

    Four point bending tests with acoustic emission (AE) monitoring were conducted for evaluating failure behavior of the plasma-sprayed hydroxyapatite (HAp) top coat on commercially pure titanium (cp-Ti) plate with and without mixed HAp/Ti bond coat. Effect of immersion in simulated body fluid (SBF) on failure behavior of the coated specimen was also investigated by immersing the specimen in SBF. The AE patterns obtained from the bending test of the HAp coating specimens after a week immersion in SBF clearly showed the earlier stage of delamination and spallation of the coating layer compared to those without immersion in SBF. It was also found that the bond coating improved failure resistance of the HAp coating specimen compared to that without the bond coat. Four point bend fatigue tests under ambient and SBF environments were also conducted with AE monitoring during the entire fatigue test for investigating the influence of SBF environment on fatigue failure behavior of the HAp coating specimen with the mixed HAp/Ti bond coat. The specimens tested at a stress amplitude of 120 MPa under both ambient and SBF environments could survive up to 10⁷ cycles without spallation of HAp coating layer. The specimens tested under SBF environment and those tested under ambient environment after immersion in SBF showed shorter fatigue life compared to those tested under ambient environment without SBF immersion. Micro-cracks nucleated in the coating layer in the early stage of fatigue life and then propagated into the cp-Ti substrate in the intermediate stage, which unstably propagated to failure in the final stage. It was found from the XRD analysis that the dissolution of the co-existing phases and the precipitation of the HAp phase were taken place during immersion in SBF. During this process, the co-existing phases disappeared from the coating layer and the HAp phase fully occupied the coating layer. The degradation of bending strength and fatigue life of the HAp coating

  12. [Effects of thermal and mechanical cycling on the metal-ceramic bond strength of machine-milled Ti2448 alloy and pure titanium].

    PubMed

    Yong, Tan; Bo, Gao

    2016-02-01

    To evaluate the effects of thermal and mechanical cycling on the metal-ceramic bond strength of machine-milled Ti2448 alloy and commercial pure titanium (cp Ti). Ceramic-cp Ti (n = 30) specimens and ceramic-Ti2448 combinations (n = 30) were prepared in accordance with ISO 9693. The specimens from each metal-ceramic combination were randomly divided into three subgroups. In group A or the control group, the specimens were only stored in distilled water for 24 h at 37 °C; in groups B and C, the specimens were subjected to 3,000 cycles of thermal cycling between 5 and 55 °C for a dwell time of 60 s and to mechanical cycling of 20,000 or 40,000 cycles with 50 N load and 4 Hz in distilled water at 37 °C. A crack initiation test was performed using a universal testing machine in accordance with ISO 9693. Failure types at the metal-ceramic interface and the morphological and elemental composition of this interface were analyzed using a scanning electron microscope and an energy dispersive spectrometer. Statistical analysis was performed via two-way ANOVA and Tukey's adjustment test (α = 0.05). The bond strength of the ceramic-Ti2448 combination was significantly higher than that of the ceramic-cp Ti combination regardless of fatigue conditions (44.86 MPa ± 1.75 MPa and 29.21 MPa ± 2.20 MPa for Ti2448 and cp Ti, respectively; P < 0.01). The mean bond strengths of ceramic-cp Ti and ceramic-Ti2448 combinations in group C were significantly lower than that of group A (P < 0.01). Although ceramic-cp Ti combination failed adhesively at the metal-ceramic interface without the ceramic on the substrate surface, Ti2448 frameworks exhibited cohesive failure; as a result, large amounts of residual porcelain were retained on the specimens. The metal-ceramic bond strength of cp Ti and Ti2448 is decreased by thermal and mechanical cycling.

  13. Titanium Brazing for Structures and Survivability

    DTIC Science & Technology

    2007-05-01

    first method ( Weld +HIP) was a tungsten inert gas ( TIG ) weld around the exterior of the Ti- 6Al-4V blocks followed by hot isostatic pressing (HIP) at...structural material is much less mature than both steel and aluminum alloys, especially in the area of joining. While welding is the typical joining...method for titanium, vacuum brazing is an option in areas that are difficult to access for welding as well as areas near other nonmetallic

  14. Behavior of Ti-5Al-2.5Sn ELI titanium alloy sheet parent and weld metal in the presence of cracks at 20 K

    NASA Technical Reports Server (NTRS)

    Sullivan, T. L.

    1971-01-01

    Through- and surface-cracked specimens of two thicknesses were tested in uniaxial tension. Surface-cracked specimens were generally found to be stronger than through-cracked specimens with the same crack length. Apparent surface-crack fracture toughness calculated using the Anderson modified Irwin equation remained relatively constant for cracks as deep as 90 percent of the sheet thickness. Subcritical growth of surface cracks was investigated. Comparison of chamber and open air welds showed chamber welds to be slightly tougher. Both methods produced welds with toughness that compared favorably with that of the parent metal. Weld efficiencies were above 94 percent.

  15. Reconditioning medical prostheses by welding

    NASA Astrophysics Data System (ADS)

    Rontescu, C.; Cicic, D. T.; Vasile, I. M.; Bogatu, A. M.; Amza, C. G.

    2017-08-01

    After the technological process of making, some of the medical prostheses may contain imperfections, which can lead to framing the product in the spoilage category. This paper treats the possibility of reconditioning by welding of the prosthesis made of titanium alloys. The paper presents the obtained results after the reconditioning by welding, using the GTAW process, of a intramedullary rod type prosthesis in which was found a crack after the non-destructive examination. The obtained result analysis, after the micrographic examination of the welded joint areas, highlighted that the process of reconditioning by welding can be applied successfully in such situations.

  16. Performance of a Scanning Mobility Particle Sizer in Measuring Diverse Types of Airborne Nanoparticles: Multi-Walled Carbon Nanotubes, Welding Fumes, and Titanium Dioxide Spray

    PubMed Central

    Chen, Bean T.; Schwegler-Berry, Diane; Cumpston, Amy; Cumpston, Jared; Friend, Sherri; Stone, Samuel; Keane, Michael

    2016-01-01

    Direct-reading instruments have been widely used for characterizing airborne nanoparticles in inhalation toxicology and industrial hygiene studies for exposure/risk assessments. Instruments using electrical mobility sizing followed by optical counting, e.g., scanning or sequential mobility particle spectrometers (SMPS), have been considered as the “gold standard” for characterizing nanoparticles. An SMPS has the advantage of rapid response and has been widely used, but there is little information on its performance in assessing the full spectrum of nanoparticles encountered in the workplace. In this study, an SMPS was evaluated for its effectiveness in producing “monodisperse” aerosol and its adequacy in characterizing overall particle size distribution using three test aerosols, each mimicking a unique class of real-life nanoparticles: singlets of nearly spherical titanium dioxide (TiO2), agglomerates of fiber-like multi-walled carbon nanotube (MWCNT), and aggregates that constitutes welding fume (WF). These aerosols were analyzed by SMPS, cascade impactor, and by counting and sizing of discrete particles by scanning and transmission electron microscopy. The effectiveness of the SMPS to produce classified particles (fixed voltage mode) was assessed by examination of the resulting geometric standard deviation (GSD) from the impactor measurement. Results indicated that SMPS performed reasonably well for TiO2 (GSD = 1.3), but not for MWCNT and WF as evidenced by the large GSD values of 1.8 and 1.5, respectively. For overall characterization, results from SMPS (scanning voltage mode) exhibited particle-dependent discrepancies in the size distribution and total number concentration compared to those from microscopic analysis. Further investigation showed that use of a single-stage impactor at the SMPS inlet could distort the size distribution and underestimate the concentration as shown by the SMPS, whereas the presence of vapor molecules or atom clusters in

  17. Performance of a scanning mobility particle sizer in measuring diverse types of airborne nanoparticles: Multi-walled carbon nanotubes, welding fumes, and titanium dioxide spray.

    PubMed

    Chen, Bean T; Schwegler-Berry, Diane; Cumpston, Amy; Cumpston, Jared; Friend, Sherri; Stone, Samuel; Keane, Michael

    2016-07-01

    Direct-reading instruments have been widely used for characterizing airborne nanoparticles in inhalation toxicology and industrial hygiene studies for exposure/risk assessments. Instruments using electrical mobility sizing followed by optical counting, e.g., scanning or sequential mobility particle spectrometers (SMPS), have been considered as the "gold standard" for characterizing nanoparticles. An SMPS has the advantage of rapid response and has been widely used, but there is little information on its performance in assessing the full spectrum of nanoparticles encountered in the workplace. In this study, an SMPS was evaluated for its effectiveness in producing "monodisperse" aerosol and its adequacy in characterizing overall particle size distribution using three test aerosols, each mimicking a unique class of real-life nanoparticles: singlets of nearly spherical titanium dioxide (TiO2), agglomerates of fiber-like multi-walled carbon nanotube (MWCNT), and aggregates that constitutes welding fume (WF). These aerosols were analyzed by SMPS, cascade impactor, and by counting and sizing of discrete particles by scanning and transmission electron microscopy. The effectiveness of the SMPS to produce classified particles (fixed voltage mode) was assessed by examination of the resulting geometric standard deviation (GSD) from the impactor measurement. Results indicated that SMPS performed reasonably well for TiO2 (GSD = 1.3), but not for MWCNT and WF as evidenced by the large GSD values of 1.8 and 1.5, respectively. For overall characterization, results from SMPS (scanning voltage mode) exhibited particle-dependent discrepancies in the size distribution and total number concentration compared to those from microscopic analysis. Further investigation showed that use of a single-stage impactor at the SMPS inlet could distort the size distribution and underestimate the concentration as shown by the SMPS, whereas the presence of vapor molecules or atom clusters in some test

  18. Morphology of the surface of technically pure titanium VT1-0 after electroexplosive carbonization with a weighed zirconium oxide powder sample and electron beam treatment

    SciTech Connect

    Sosnin, Kirill V.; Raykov, Sergey V.; Vaschuk, Ekaterina S.; Budovskikh, Evgenie A. Gromov, Victor E.; Ivanov, Yuri F.

    2014-11-14

    Titanium is carbonized by the electroexplosive method. Formation of a surface alloyed layer and a coating on the treated surface is established by the methods of transmission electron microscopy. The morphology and elemental composition of the alloyed layer are analyzed. A dependence of the structure of the modified layer subjected to electron gun treatment on the absorbed power density is revealed.

  19. Characteristics of the surface oxides on turned and electrochemically oxidized pure titanium implants up to dielectric breakdown: the oxide thickness, micropore configurations, surface roughness, crystal structure and chemical composition.

    PubMed

    Sul, Young-Taeg; Johansson, Carina B; Petronis, Sarunas; Krozer, Anatol; Jeong, Yongsoo; Wennerberg, Ann; Albrektsson, Tomas

    2002-01-01

    Titanium implants have been used widely and successfully for various types of bone-anchored reconstructions. It is believed that properties of oxide films covering titanium implant surfaces are of crucial importance for a successful osseointegration, in particular at compromized bone sites. The aim of the present study is to investigate the surface properties of anodic oxides formed on commercially pure (c.p.) titanium screw implants as well as to study 'native' oxides on turned c.p. titanium implants. Anodic oxides were prepared by galvanostatic mode in CH3COOH up to the high forming voltage of dielectric breakdown and spark formation. The oxide thicknesses, measured with Auger electron spectroscopy (AES), were in the range of about 200-1000 nm. Barrier and porous structures dominated the surface morphology of the anodic film. Quantitative morphometric analyses of the micropore structures were performed using an image analysis system on scanning electron microscopy (SEM) negatives. The pore sizes were < or = 8 microm in diameter and had 1.27-2.1 microm2 opening area. The porosity was in the range of 12.7-24.4%. The surface roughness was in the range of 0.96-1.03 microm (Sa), measured with TopScan 3D. The crystal structures of the titanium oxide were amorphous, anatase, and a mixtures of anatase and rutile type, as analyzed with thin-film X-ray diffractometry (TF-XRD) and Raman spectroscopy. The chemical compositions consisted mainly of TiO2, characterized with X-ray photoelectron spectroscopy (XPS). The native (thermal) oxide on turned implants was 17.4 nm (+/- 6.2) thick and amorphous. Its chemical composition was TiO2. The surface roughness had an average height deviation of 0.83 microm (Sa). The present results are needed to elucidate the influence of the oxide properties on the biological reaction. The results of animal studies using the presently characterized surface oxides on titanium implants will be published separately.

  20. Cytotoxic effects of four types of welding fumes on macrophages in vitro: a comparative study

    SciTech Connect

    Pasanen, J.T.; Gustafsson, T.E.; Kalliomaeki, P.L.T.; Tossavainen, A.; Jaervisalo, J.O.

    1986-01-01

    The effects of fume particles given off by the manual metal arc (MMA) and metal inert gas (MIG) welding of stainless steel (SS) and mild steel (MS) were studied on rat alveolar macrophage cultures in vitro. The fumes were generated by welding, and particulate material obtained was collected on membrane filters. The macrophage cultures were exposed to the total dust and to its water-insoluble fractions. Cell variability and the release of both lactate dehydrogenase and one lysosomal enzyme from the cells to the medium were measured after an exposure period of 24 h. The cytotoxic control dust was DQ 12 quartz, and the inert control dust was pure titanium dioxide. According to the parameters studied, SS/MMA and MS/MMA welding fumes were cytotoxic to rat alveolar macrophages. The cytotoxic effect of SS/MMA welding fumes decreased after the samples had been washed with phosphate-buffered salt solution. The MIG welding fumes of SS and MS had markedly smaller effects on the cells. Diluted solutions of potassium chromate were also tested in order to investigate its role in the cytotoxicity of SS/MMA welding fumes. The results suggest that hexavalent chromium may be responsible for the cytotoxicity of SS/MMA.

  1. Current welding consumables research in the U.S. Navy

    SciTech Connect

    DeLoach, J.J. Jr.; Franke, G.L.; Vassilaros, M.G.; Wong, R.J.

    1993-12-31

    US Navy research is being conducted on a number of topics pertaining to welding Navy steels with yield strengths exceeding 690 MPa. Four tasks are discussed in this presentation. HSLA-100 Welding Consumables Development addresses evaluation of experimental compositions, data analysis, and identification of optimum compositions. Low-Carbon Bainitic Weld Metals discusses the effects of alloying on weld metal strength and cooling rate sensitivity, and the effect of titanium-bearing inclusions on weld toughness. Weldability Methodology addresses weldability tests, diffusible hydrogen, and cracking models. Welding Fluxes discusses determination of flux composition and correlations with weld performance. Future research for each task is also described.

  2. A comparison of the stress corrosion cracking susceptibility of commercially pure titanium grade 4 in Ringer's solution and in distilled water: a fracture mechanics approach.

    PubMed

    Roach, Michael D; Williamson, R Scott; Thomas, Joseph A; Griggs, Jason A; Zardiackas, Lyle D

    2014-01-01

    From the results of laboratory investigations reported in the literature, it has been suggested that stress corrosion cracking (SCC) mechanisms may contribute to early failures in titanium alloys that have elevated oxygen concentrations. However, the susceptibility of titanium alloys to SCC in physiological environments remains unclear. In this study, a fracture mechanics approach was used to examine the SCC susceptibility of CP titanium grade 4 in Ringer's solution and distilled de-ionized (DI) water, at 37°C. The study duration was 26 weeks, simulating the non-union declaration of a plated fracture. Four wedge loads were used corresponding to 86-95% of the alloy's ligament yield load. The longest cracks were measured to be 0.18 mm and 0.10 mm in Ringer's solution and DI water, respectively. SEM analysis revealed no evidence of extensive fluting and quasi-cleavage fracture features which, in literature reports, were attributed to SCC. We thus postulate that the Ringer's solution accelerated the wedge-loaded crack growth without producing the critical stresses needed to change the fracture mechanism. Regression analysis of the crack length results led to a significant best-fit relationship between crack growth velocity (independent variable) and test electrolyte, initial wedge load, and time of immersion of specimen in electrolyte (dependent variables).

  3. Underwater wet welding consumables for offshore applications

    SciTech Connect

    Sanchez-Osio, A.; Liu, S.; Olson, D.L.; Ibarra, S.

    1993-12-31

    The use of underwater wet welding for offshore repairs has been limited mainly because of porosity in the resulting welds. With appropriate consumable design, however, it is possible to enhance weld metal toughness through microstructural refinement and to reduce porosity. New titanium and boron based consumables have been developed with which high toughness acicular ferrite can be produced in underwater wet welds. Titanium, by means of oxide formation, promoted an increase in weld metal acicular ferrite, while boron additions decreased the amount of grain boundary ferrite, further improving the microstructure. Porosity reduction was possible through the addition of calcium carbonate at approximately 13 wt. % in the coating. However, weld metal decarburization also resulted with the addition.

  4. Submerged Arc Welding of Titanium.

    DTIC Science & Technology

    1978-09-30

    slag control. 7) Further developmental work was necessary. Following Petsch’s work, Union Carbide Corporation, under contract to the Office of Naval...crucibles under argon. However, subsequent X—ray analysis indicated that this fusion technique resulted in 1 to 37. CaO impurity formation from adsorbed...this source would probably not produce a large quantity of nitrogen; however, all flux was fused under argon in order to prevent any such

  5. Welding Research

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Welding fabrication and welding processes were studied. The following research projects are reported: (1) welding fabrication; (2) residual stresses and distortion in structural weldments in high strength steels; (3) improvement of reliability of welding by in process sensing and control (development of smart welding machines for girth welding of pipes); (4) development of fully automated and integrated welding systems for marine applications; (5) advancement of welding technology; (6) research on metal working by high power laser (7) flux development; (8) heat and fluid flow; (9) mechanical properties developments.

  6. New Method For Joining Stainless Steel to Titanium

    NASA Technical Reports Server (NTRS)

    Emanuel, W. H.

    1982-01-01

    In new process, edge of stainless-steel sheet is perforated, and joined to titanium by resistance seam welding. Titanium flows into perforations, forming a strong interlocking joint. Process creates a quasi-metallurgical bond between the thin sheets of stainless steel and titanium.

  7. The effect of mucine, IgA, urea, and lysozyme on the corrosion behavior of various non-precious dental alloys and pure titanium in artificial saliva.

    PubMed

    Bilhan, H; Bilgin, T; Cakir, A F; Yuksel, B; Von Fraunhofer, J A

    2007-11-01

    The corrosion of dental alloys has biological, functional, and aesthetic consequences. Various studies have shown that protein solutions can inhibit the corrosion of alloys. This study is planned to determine the relationship of organic constituents of saliva and the corrosion of dental alloys. The organic constituents are IgA, mucine, urea, and lysozyme which are encountered in the highest amounts in saliva and the dental materials are titanium (Ti), Co-Cr-Mo and Ni-Cr-Mo alloys, and dental amalgam, the most often used metallic components in dentistry. In particular, the interactions between the commonest salivary proteins, IgA, mucine, urea and lysozyme, and Ti, Co-Cr-Mo, Ni-Cr-Mo and dental amalgam were investigated. Each alloy was evaluated by cyclic polarization in each medium. The general anodic and cathodic behavior during forward and reverse cycles, the corrosion and passivation current densities (muA/cm2 ), and the corrosion and the pitting potentials (mV) were determined. The results have shown that Ni-Cr-Mo and dental amalgam alloys are highly susceptible to corrosion in all the investigated media. The Co-Cr-Mo alloy has shown high passive current densities in the solution of mucine and lysozyme in artificial saliva. Titanium instead, has shown a high resistance to corrosion and a stable passive behavior in all media, especially in a solution of mucine and IgA in synthetic saliva. Mucine and IgA, as well as urea and lysozyme, appeared to enhance the formation of a passive film layer on the Ti metal surface, thus inhibiting the corrosion. Based on the study findings, and especially considering the problem of nickel allergy and toxicity of mercury released from dental amalgam, the use of Co-Cr-Mo alloys and Ti to Ni-Cr-Mo alloys is recommended and alternatives to dental amalgam should be sought for patients with impaired salivary flow.

  8. Nonchamber, Root-Side, Inert-Gas Purging During Welding

    NASA Technical Reports Server (NTRS)

    Mcgee, William F.; Rybicki, Daniel J.

    1995-01-01

    Improved apparatus distributes inert gas to protect against oxidation on root side of weld during welding and after welding while joint remains hot. Simple and lightweight; readily moved along weld path in synchronism with torch. Because it concentrates inert gas where needed, consumes gas at relatively low rate, and not necessary to monitor oxygen content of protective atmosphere. Apparatus does not obscure view of root side of weld. Used for full-penetration plasma-arc welding of such reactive metals as aluminum/lithium alloys and titanium.

  9. Tissue stimulator enclosure welding fixture

    NASA Technical Reports Server (NTRS)

    Mcclure, S. R.

    1977-01-01

    It was demonstrated that the thickness of the stimulator titanium enclosure is directly related to the battery recharge time cycle. Reduction of the titanium enclosure thickness from approximately 0.37 mm (0.015 inch) to 0.05 mm (0.002 inch) significantly reduced the recharge time cycle and thereby patient inconvenience. However, fabrication of titanium enclosures from the thinner material introduced problems in forming, holding, and welding that required improvement in state of the art shop practices. The procedures that were utilized to resolve these fabrication problems are described.

  10. Investigation of Torsional Strength of the VT6 Weld Joint Produced by Linear Friction Welding

    NASA Astrophysics Data System (ADS)

    Suleimanova, G. R.; Kabirov, R. R.; Karavaeva, M. V.; Ershova, Yu. A.; Zhilyaev, A. P.

    2015-10-01

    Results of measurement of torsional strength of the weld joint of the VT6 titanium alloy produced by linear friction welding are presented. For a comparison, the same method was used to test monolithic specimens of the VT6 alloy. Torsional strength values of the weld joint (τUS = 861 MPa and φ = 110°) correspond to the strength of the monolithic material. In this case, the specimens fail along the base metal.

  11. Welding Curriculum.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Education, Juneau. Div. of Adult and Vocational Education.

    This competency-based curriculum guide is a handbook for the development of welding trade programs. Based on a survey of Alaskan welding employers, it includes all competencies a student should acquire in such a welding program. The handbook stresses the importance of understanding the principles associated with the various elements of welding.…

  12. Welding IV.

    ERIC Educational Resources Information Center

    Allegheny County Community Coll., Pittsburgh, PA.

    Instructional objectives and performance requirements are outlined in this course guide for Welding IV, a competency-based course in advanced arc welding offered at the Community College of Allegheny County to provide students with proficiency in: (1) single vee groove welding using code specifications established by the American Welding Society…

  13. Welding IV.

    ERIC Educational Resources Information Center

    Allegheny County Community Coll., Pittsburgh, PA.

    Instructional objectives and performance requirements are outlined in this course guide for Welding IV, a competency-based course in advanced arc welding offered at the Community College of Allegheny County to provide students with proficiency in: (1) single vee groove welding using code specifications established by the American Welding Society…

  14. Automatic orbital GTAW welding: Highest quality welds for tomorrow's high-performance systems

    NASA Technical Reports Server (NTRS)

    Henon, B. K.

    1985-01-01

    Automatic orbital gas tungsten arc welding (GTAW) or TIG welding is certain to play an increasingly prominent role in tomorrow's technology. The welds are of the highest quality and the repeatability of automatic weldings is vastly superior to that of manual welding. Since less heat is applied to the weld during automatic welding than manual welding, there is less change in the metallurgical properties of the parent material. The possibility of accurate control and the cleanliness of the automatic GTAW welding process make it highly suitable to the welding of the more exotic and expensive materials which are now widely used in the aerospace and hydrospace industries. Titanium, stainless steel, Inconel, and Incoloy, as well as, aluminum can all be welded to the highest quality specifications automatically. Automatic orbital GTAW equipment is available for the fusion butt welding of tube-to-tube, as well as, tube to autobuttweld fittings. The same equipment can also be used for the fusion butt welding of up to 6 inch pipe with a wall thickness of up to 0.154 inches.

  15. Advanced Welding Concepts

    NASA Technical Reports Server (NTRS)

    Ding, Robert J.

    2010-01-01

    Four advanced welding techniques and their use in NASA are briefly reviewed in this poster presentation. The welding techniques reviewed are: Solid State Welding, Friction Stir Welding (FSW), Thermal Stir Welding (TSW) and Ultrasonic Stir Welding.

  16. Advanced Welding Science for DoD Application. The Genesis of the Army Welding Microfactory, Workshop held in Golden, Colorado on March 20+-22, 1991

    DTIC Science & Technology

    1991-06-01

    2000). 39 5.3.7 Welding and Joinint Consumables Presen 1995 22005 (a) Aluminum-Lithium and Composite Fillers (b) Hardfacing (c) Lov Cost Titanium...filler alloys need to be investigated for unique weld metal properties (1991). HARDFACING (22) Welded overlay band process for artillery rotating

  17. Experimental titanium alloys for dental applications.

    PubMed

    Faria, Adriana C L; Rodrigues, Renata C S; Rosa, Adalberto L; Ribeiro, Ricardo F

    2014-12-01

    Although the use of titanium has increased, casting difficulties limit routine use. The purpose of the present study was to compare the mechanical properties and biocompatibility of the experimental titanium alloys titanium-5-zirconium, titanium-5-tantalum, and titanium-5-tantalum-5-zirconium (in wt%) with those of commercially pure titanium. Specimens of titanium alloys and commercially pure titanium were cast by using plasma. Their modulus of elasticity and ultimate tensile strength were determined in a universal testing machine. Biocompatibility was evaluated with SCC9 cells. In periods of 1, 4, 7, 10, and 14 days, cell proliferation was evaluated by the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium reduction assay, and cell viability was evaluated in the 7-day period. Cell morphology was evaluated at 2, 12, and 24 hours. Modulus of elasticity, ultimate tensile strength, and cell viability were analyzed by 1-way ANOVA and the Bonferroni test; cell proliferation data were compared by 2-way ANOVA (alloy versus time) and by the Bonferroni test; and the cell morphology data were analyzed by split-plot design. All statistical tests were performed at the 95% confidence level (P<.05). Titanium-5-tantalum presented the lowest modulus of elasticity and ultimate tensile strength, whereas titanium-5-zirconium and titanium-5-tantalum-5-zirconium were statistically similar to commercially pure titanium. Cell proliferation and viability were not affected by any alloy being similar to those observed for commercially pure titanium. No noticeably differences were found in the morphology of cells cultured on any alloy and commercially pure titanium. Experimental alloys, especially titanium-5-zirconium and titanium-5-tantalum-5-zirconium, presented promising mechanical results for future studies and clinical applications. In addition, these alloys, evaluated by cell proliferation, viability, and morphology, were found to be biocompatible in vitro

  18. In-process monitoring and adaptive control for gap in micro butt welding with pulsed YAG laser

    NASA Astrophysics Data System (ADS)

    Kawahito, Yousuke; Kito, Masayuki; Katayama, Seiji

    2007-05-01

    A gap is one of the most important issues to be solved in laser welding of a micro butt joint, because the gap results in welding defects such as underfilling or a non-bonded joint. In-process monitoring and adaptive control has been expected as one of the useful procedures for the stable production of sound laser welds without defects. The objective of this research is to evaluate the availability of in-process monitoring and adaptive control in micro butt welding of pure titanium rods with a pulsed neodymium : yttrium aluminium garnet (Nd : YAG) laser beam of a 150 µm spot diameter. It was revealed that a 45 µm narrow gap was detected by the remarkable jump in a reflected light intensity due to the formation of the molten pool which could bridge the gap. Heat radiation signal levels increased in proportion to the sizes of molten pools or penetration depths for the respective laser powers. As for adaptive control, the laser peak power was controlled on the basis of the reflected light or the heat radiation signals to stably produce a sound deeply penetrated weld reduced underfilling. In the case of a 100 µm gap, the underfilling was greatly reduced by half smaller than those made with a conventional rectangular pulse shape in seam welding as well as spot welding with a pulsed Nd : YAG laser beam. Consequently, the adaptive control of the laser peak power on the basis of in-process monitoring could reduce the harmful effects due to a gap in micro butt laser welding with a pulsed laser beam.

  19. Welding Technician

    ERIC Educational Resources Information Center

    Smith, Ken

    2009-01-01

    About 95% of all manufactured goods in this country are welded or joined in some way. These welded products range in nature from bicycle handlebars and skyscrapers to bridges and race cars. The author discusses what students need to know about careers for welding technicians--wages, responsibilities, skills needed, career advancement…

  20. Welding Technician

    ERIC Educational Resources Information Center

    Smith, Ken

    2009-01-01

    About 95% of all manufactured goods in this country are welded or joined in some way. These welded products range in nature from bicycle handlebars and skyscrapers to bridges and race cars. The author discusses what students need to know about careers for welding technicians--wages, responsibilities, skills needed, career advancement…

  1. Influence of Solute Content and Solidification Parameters on Grain Refinement of Aluminum Weld Metal

    NASA Astrophysics Data System (ADS)

    Schempp, Philipp; Cross, Carl Edward; Pittner, Andreas; Rethmeier, Michael

    2013-07-01

    Grain refinement provides an important possibility to enhance the mechanical properties ( e.g., strength and ductility) and the weldability (susceptibility to solidification cracking) of aluminum weld metal. In the current study, a filler metal consisting of aluminum base metal and different amounts of commercial grain refiner Al Ti5B1 was produced. The filler metal was then deposited in the base metal and fused in a GTA welding process. Additions of titanium and boron reduced the weld metal mean grain size considerably and resulted in a transition from columnar to equiaxed grain shape ( CET). In commercial pure aluminum (Alloy 1050A), the grain-refining efficiency was higher than that in the Al alloys 6082 and 5083. Different welding and solidification parameters influenced the grain size response only slightly. Furthermore, the observed grain-size reduction was analyzed by means of the undercooling parameter P and the growth restriction parameter Q, which revealed the influence of solute elements and nucleant particles on grain size.

  2. The investigation of ultrasonic mechanical forging influence on the structure and mechanical properties of VT23 welded joints by methods of laser and electron beam welding

    NASA Astrophysics Data System (ADS)

    Smirnova, A. S.; Pochivalov, Yu. I.; Panin, V. E.; Orishich, A. M.; Malikov, A. G.; Fomin, V. M.

    2016-11-01

    The structure and mechanical properties of welded joints of VT23 titanium alloy received by methods of laser and electron beam welding with subsequent thermomechanical treatment (TMP1 and TMP2) including ultrasonic mechanical forging are investigated. X-ray structure analysis, scanning electron and transmission electron microscopy have revealed the features of phase structure, microstructure and fractography of welded joints after electron beam and laser welding with subsequent ultrasonic mechanical forging. Application of ultrasonic mechanical forging of welded joints produced by electron beam and laser welding has allowed increasing fatigue life of samples of welded joints after laser welding from 6369 to 19 569 cycles and from 54 616 cycles to 77 126 cycles for electron beam welding. Thus, the application of ultrasonic mechanical forging can significantly raise fatigue and mechanical characteristics of welded connections.

  3. Reduction of titanium dioxide to metallic titanium conducted under the autogenic pressure of the reactants.

    PubMed

    Eshed, Michal; Irzh, Alexander; Gedanken, Aharon

    2009-08-03

    We report on a reaction to convert titanium dioxide to titanium. The reduction reaction was done under the autogenic pressure of the reactants at 750 degrees C for 5 h. The MgO, a by-product, was removed by acids to obtain pure metallic titanium.

  4. Elements of arc welding

    SciTech Connect

    Not Available

    1993-07-01

    This paper looks at the following arc welding techniques: (1) shielded metal-arc welding; (2) submerged-arc welding; (3) gas metal-arc welding; (4) flux-cored arc welding; (5) electrogas welding; (6) gas tungsten-arc welding; and (7) plasma-arc welding.

  5. A superior process for forming titanium hydrogen isotopic films

    NASA Technical Reports Server (NTRS)

    Steinberg, R.; Alger, D. L.; Cooper, D. W.

    1975-01-01

    Process forms stoichiometric, continuous, strongly bonded titanium hydrogen isotopic films. Films have thermal and electrical conductivities approximately the same as bulk pure titanium, ten times greater than those of usual thin films.

  6. An experimental method for investigating phase transformations in the heat affected zone of welds using synchrotron radiation

    SciTech Connect

    Elmer, J.W.; Wong, J.; Froba, M.; Waide, P.A.; Larson, E.M.

    1995-05-26

    Although welding is an established technology used in many industrial settings, it is least understand terms of the phases that actually exist, the variation of their spatial disposition with time, and the rate of transformation from one phase to another at various thermal coordinates in the vicinity of the weld. With the availability of high flux and, more recently, high brightness synchrotron x-radiation sources, a number of diffraction and spectroscopic methods have been developed for structural characterization with improved spatial and temporal resolutions to enable in-situ measurements of phases under extreme temperature, pressure and other processing conditions not readily accessible with conventional sources. This paper describes the application of spatially resolved x-ray diffraction (SRXRD) for in-situ investigations of phase transformations in the heat affected zone (HAZ) of fusion welds. Results are presented for gas tungsten (GTA) welds in commercially pure titanium that show the existence of the high temperature bcc {beta}-phase in a 3.3 {plus_minus} 0.3 mm wide HA band adjacent to the liquid weld pool. Phase concentration profiles derived from the SRXRD data further show the co-existence of both the low temperature hcp ({alpha}-phase and the {beta}-phase in the partially, transformed region of the HA. These results represent the first direct observations of solid state phase transformations and mapping of phase boundaries in fusion welds. SRXRD experiments of this type are needed as experimental input for modeling of kinetics of phase transformations and microstructural evolution under the highly non-isothermal conditions produced during welding.

  7. Soldadura (Welding). Spanish Translations for Welding.

    ERIC Educational Resources Information Center

    Hohhertz, Durwin

    Thirty transparency masters with Spanish subtitles for key words are provided for a welding/general mechanical repair course. The transparency masters are on such topics as oxyacetylene welding; oxyacetylene welding equipment; welding safety; different types of welds; braze welding; cutting torches; cutting with a torch; protective equipment; arc…

  8. Soldadura (Welding). Spanish Translations for Welding.

    ERIC Educational Resources Information Center

    Hohhertz, Durwin

    Thirty transparency masters with Spanish subtitles for key words are provided for a welding/general mechanical repair course. The transparency masters are on such topics as oxyacetylene welding; oxyacetylene welding equipment; welding safety; different types of welds; braze welding; cutting torches; cutting with a torch; protective equipment; arc…

  9. Effect of Pre- and Post-weld Heat Treatments on Linear Friction Welded Ti-5553

    NASA Astrophysics Data System (ADS)

    Wanjara, Priti; Dalgaard, Elvi; Gholipour, Javad; Cao, Xinjin; Cuddy, Jonathan; Jonas, John J.

    2014-10-01

    Linear friction welding allows solid-state joining of near-beta ( β) titanium alloy Ti-5553 (Ti-5Al-5V-5Mo-3Cr). In the as-welded condition, the weld zone (WZ) exhibits β grain refinement and marked softening as compared with Ti-5553 in the solution heat treated and aged condition. The softening of the weldment is attributed to the depletion of the strengthening alpha ( α) phase in the WZ and the adjacent thermo-mechanically affected zone (TMAZ). Specifically, in near- β titanium alloys, the strength of the material mainly depends on the shape, size, distribution, and fraction of the primary α and other decomposition products of the β phase. Hence, a combination of pre- and post-weld heat treatments were applied to determine the conditions that allow mitigating the α phase depletion in the WZ and TMAZ of the welds. The mechanical response of the welded samples to the heat treatments was determined by performing microhardness measurements and tensile testing at room temperature with an automated 3D deformation measurement system. It was found that though the joint efficiency in the as-welded condition was high (96 pct), strain localization and failure occurred in the TMAZ. The application of post-weld solution heat treatment with aging was effective in restoring α, increasing the joint efficiency (97 to 99 pct) and inducing strain localization and failure in the parent material region.

  10. WELDING TORCH

    DOEpatents

    Correy, T.B.

    1961-10-01

    A welding torch into which water and inert gas are piped separately for cooling and for providing a suitable gaseous atmosphere is described. A welding electrode is clamped in the torch by a removable collet sleeve and a removable collet head. Replacement of the sleeve and head with larger or smaller sleeve and head permits a larger or smaller welding electrode to be substituted on the torch. (AEC)

  11. The Effect of Welding Energy on the Microstructural and Mechanical Properties of Ultrasonic-Welded Copper Joints

    PubMed Central

    Yang, Jingwei; Cao, Biao; Lu, Qinghua

    2017-01-01

    The effects of welding energy on the mechanical and microstructural characteristics of ultrasonic-welded pure copper plates were investigated. Complex dynamic recrystallization and grain growth occurred inside the weld zone during ultrasonic welding. At a low welding energy, a thin band of straight weld interfaces was observed and had an ultra-fine grain structure. With an increase in welding energy, the weld interface progressively changed from flat to sinusoidal, and eventually turned into a convoluted wavy pattern, bearing similarities to shear instabilities, as observed in fluid dynamics. The lap shear load of the joints initially increased and then remained stable as the welding energy increased. The tensile characteristics of the joints significantly depended on the development of plastic deformation at the interface. The influence of the microstructure on the hardness was also discussed. PMID:28772553

  12. Intermetallic alloy welding wires and method for fabricating the same

    DOEpatents

    Santella, M.L.; Sikka, V.K.

    1996-06-11

    Welding wires for welding together intermetallic alloys of nickel aluminides, nickel-iron aluminides, iron aluminides, or titanium aluminides, and preferably including additional alloying constituents are fabricated as two-component, clad structures in which one component contains the primary alloying constituent(s) except for aluminum and the other component contains the aluminum constituent. This two-component approach for fabricating the welding wire overcomes the difficulties associated with mechanically forming welding wires from intermetallic alloys which possess high strength and limited ductilities at elevated temperatures normally employed in conventional metal working processes. The composition of the clad welding wires is readily tailored so that the welding wire composition when melted will form an alloy defined by the weld deposit which substantially corresponds to the composition of the intermetallic alloy being joined. 4 figs.

  13. Intermetallic alloy welding wires and method for fabricating the same

    DOEpatents

    Santella, Michael L.; Sikka, Vinod K.

    1996-01-01

    Welding wires for welding together intermetallic alloys of nickel aluminides, nickel-iron aluminides, iron aluminides, or titanium aluminides, and preferably including additional alloying constituents are fabricated as two-component, clad structures in which one component contains the primary alloying constituent(s) except for aluminum and the other component contains the aluminum constituent. This two-component approach for fabricating the welding wire overcomes the difficulties associated with mechanically forming welding wires from intermetallic alloys which possess high strength and limited ductilities at elevated temperatures normally employed in conventional metal working processes. The composition of the clad welding wires is readily tailored so that the welding wire composition when melted will form an alloy defined by the weld deposit which substantially corresponds to the composition of the intermetallic alloy being joined.

  14. Development of techniques for welding V Cr Ti alloys

    NASA Astrophysics Data System (ADS)

    Grossbeck, M. L.; King, J. F.; Alexander, D. J.; Rice, P. M.; Goodwin, G. M.

    1998-10-01

    Welding vanadium alloys is complicated by interstitial impurity introduction and redistribution at elevated temperatures. Gas tungsten arc (GTA) welding, which will probably be required for the fabrication of large tokamak structures, must be done in a glove box environment. Welds were evaluated by Charpy testing. GTA welds could be made with a ductile to brittle transition temperature (DBTT) of 50°C with a post-weld heat treatment (PWHT) or by using a heated Ti getter system on the glove box to reduce interstitial contamination. Titanium-O,N,C precipitates in the fusion zone were found to transform to a more oxygen-rich phase during a PWHT of 950°C/2 h. Hydrogen was found to promote cleavage cracking following welding in cases where the atmosphere was contaminated. Grain size and microstructure also affected weld embrittlement.

  15. Plasma arc welding weld imaging

    NASA Technical Reports Server (NTRS)

    Rybicki, Daniel J. (Inventor); Mcgee, William F. (Inventor)

    1994-01-01

    A welding torch for plasma arc welding apparatus has a transparent shield cup disposed about the constricting nozzle, the cup including a small outwardly extending polished lip. A guide tube extends externally of the torch and has a free end adjacent to the lip. First and second optical fiber bundle assemblies are supported within the guide tube. Light from a strobe light is transmitted along one of the assemblies to the free end and through the lip onto the weld site. A lens is positioned in the guide tube adjacent to the second assembly and focuses images of the weld site onto the end of the fiber bundle of the second assembly and these images are transmitted along the second assembly to a video camera so that the weld site may be viewed continuously for monitoring the welding process.

  16. Effects of titanium and zirconium on iron aluminide weldments

    SciTech Connect

    Burt, R.P.; Edwards, G.R.; David, S.A.

    1996-08-01

    Iron aluminides form a coarse fusion zone microstructure when gas-tungsten arc welded. This microstructure is susceptible to hydrogen cracking when water vapor is present in the welding environment. Because fusion zone microstructural refinement can reduce the hydrogen cracking susceptibility, titanium was used to inoculate the weld pool in iron aluminide alloy FA-129. Although the fusion zone microstructure was significantly refined by this method, the fracture stress was found to decrease with titanium additions. This decrease is attributed to an increase in inclusions at the grain boundaries.

  17. Hydrogen content in titanium and a titanium-zirconium alloy after acid etching.

    PubMed

    Frank, Matthias J; Walter, Martin S; Lyngstadaas, S Petter; Wintermantel, Erich; Haugen, Håvard J

    2013-04-01

    Dental implant alloys made from titanium and zirconium are known for their high mechanical strength, fracture toughness and corrosion resistance in comparison with commercially pure titanium. The aim of the study was to investigate possible differences in the surface chemistry and/or surface topography of titanium and titanium-zirconium surfaces after sand blasting and acid etching. The two surfaces were compared by X-ray photoelectron spectroscopy, secondary ion mass spectroscopy, scanning electron microscopy and profilometry. The 1.9 times greater surface hydrogen concentration of titanium zirconium compared to titanium was found to be the major difference between the two materials. Zirconium appeared to enhance hydride formation on titanium alloys when etched in acid. Surface topography revealed significant differences on the micro and nanoscale. Surface roughness was increased significantly (p<0.01) on the titanium-zirconium alloy. High-resolution images showed nanostructures only present on titanium zirconium.

  18. A comparison of two types of neural network for weld quality prediction in small scale resistance spot welding

    NASA Astrophysics Data System (ADS)

    Wan, Xiaodong; Wang, Yuanxun; Zhao, Dawei; Huang, YongAn

    2017-09-01

    Our study aims at developing an effective quality monitoring system in small scale resistance spot welding of titanium alloy. The measured electrical signals were interpreted in combination with the nugget development. Features were extracted from the dynamic resistance and electrode voltage curve. A higher welding current generally indicated a lower overall dynamic resistance level. A larger electrode voltage peak and higher change rate of electrode voltage could be detected under a smaller electrode force or higher welding current condition. Variation of the extracted features and weld quality was found more sensitive to the change of welding current than electrode force. Different neural network model were proposed for weld quality prediction. The back propagation neural network was more proper in failure load estimation. The probabilistic neural network model was more appropriate to be applied in quality level classification. A real-time and on-line weld quality monitoring system may be developed by taking advantages of both methods.

  19. Robotic Vision for Welding

    NASA Technical Reports Server (NTRS)

    Richardson, R. W.

    1986-01-01

    Vision system for robotic welder looks at weld along axis of welding electrode. Gives robot view of most of weld area, including yet-unwelded joint, weld pool, and completed weld bead. Protected within welding-torch body, lens and fiber bundle give robot closeup view of weld in progress. Relayed to video camera on robot manipulator frame, weld image provides data for automatic control of robot motion and welding parameters.

  20. Welding III.

    ERIC Educational Resources Information Center

    Allegheny County Community Coll., Pittsburgh, PA.

    Instructional objectives and performance requirements are outlined in this course guide for Welding III, an advanced course in arc welding offered at the Community College of Allegheny County to provide students with the proficiency necessary for industrial certification. The course objectives, which are outlined first, specify that students will…

  1. Welding Curriculum.

    ERIC Educational Resources Information Center

    EASTCONN Regional Educational Services Center, North Windham, CT.

    The purpose of this welding program is to provide students with skills and techniques to become employed as advanced apprentice welders. The welding program manual includes the following sections: (1) course description; (2) general objectives; (3) competencies; (4) curriculum outline for 13 areas; (5) 13 references; and (6) student progress…

  2. Welding Curriculum.

    ERIC Educational Resources Information Center

    EASTCONN Regional Educational Services Center, North Windham, CT.

    The purpose of this welding program is to provide students with skills and techniques to become employed as advanced apprentice welders. The welding program manual includes the following sections: (1) course description; (2) general objectives; (3) competencies; (4) curriculum outline for 13 areas; (5) 13 references; and (6) student progress…

  3. Welding III.

    ERIC Educational Resources Information Center

    Allegheny County Community Coll., Pittsburgh, PA.

    Instructional objectives and performance requirements are outlined in this course guide for Welding III, an advanced course in arc welding offered at the Community College of Allegheny County to provide students with the proficiency necessary for industrial certification. The course objectives, which are outlined first, specify that students will…

  4. WELDING METHOD

    DOEpatents

    Cornell, A.A.; Dunbar, J.V.; Ruffner, J.H.

    1959-09-29

    A semi-automatic method is described for the weld joining of pipes and fittings which utilizes the inert gasshielded consumable electrode electric arc welding technique, comprising laying down the root pass at a first peripheral velocity and thereafter laying down the filler passes over the root pass necessary to complete the weld by revolving the pipes and fittings at a second peripheral velocity different from the first peripheral velocity, maintaining the welding head in a fixed position as to the specific direction of revolution, while the longitudinal axis of the welding head is disposed angularly in the direction of revolution at amounts between twenty minutas and about four degrees from the first position.

  5. Fracture Mechanical Measurements with Commercial Stainless Steels at 4 K and with Cp-Titanium at 173 K

    NASA Astrophysics Data System (ADS)

    Nyilas, A.; Mitterbacher, H.

    2010-04-01

    Using the JETT (J-Evaluation on Tensile Test) technique, measurements have been performed with commercial stainless steels in forged and cast condition for the reason of an assessment for low temperature service down to 4 K. These steels frequently used for industrial applications are designated by German Werkstoff (WNr) 1.4308 and 1.4408 cast stainless steels and a forged material with the number 1.4307. The fracture toughness tests at 4 K with forged material 1.4307 comprised apart from the base metal also the weld zone and additionally the 5% and 8% pre-strained conditions of the base metal. Fracture toughness reduced slightly for cold worked condition gradually as well as for the weld joint. The Reliability of the JETT measurements has been also checked using the ASTM E 1820—99a standard. In addition, to these measurements, commercial pure ASTM grade 2 titanium (WNr 3.7035) has been also examined using the same JETT method for the reason of industrial application and the requirement of minimum fracture toughness of 100 MPa√m was fulfilled at 173 K. Furthermore, test results performed at 7 K of pure titanium plate material (ASTM grade 1) with respect to fracture mechanical JETT method are presented.

  6. Porcelain veneering of titanium--clinical and technical aspects.

    PubMed

    Haag, Per

    2011-01-01

    Gold and other alloys have long been used for the production of crowns and bridges as replacements for damaged or lost teeth. However, doubts have arisen on the suitability of using these materials for dental restorations, as gold has also shown a capacity to cause side-effects such as allergic reactions. This is especially valid for alloys, which during the last decades have been used as porcelain-fused-to metal restorations. This fact has led to an interest in using titanium instead of these alloys. Trials to use titanium for this purpose were initiated in Japan in the early 1980s. Titanium as an unalloyed metal differs in two aspects from the above named alloys: it has a phase transformation at 882 degrees C, which changes its outer and inner properties, and it has an expansion that lies between that of the porcelain types available on the market at the time. In Japan a technique for casting titanium was developed, where the after-treatment of the casting was elaborate, to re-establish the original properties of titanium. The porcelain developed for veneering had shortcomings as the rendering produced a rough surface and non satisfactory esthetics. In Sweden a new concept was introduced in 1989. Here the processing of titanium was performed by industrial methods such as milling, spark erosion and laser welding. The idea behind this was to avoid phase transformation. During the 1990s a number of porcelain products were launched and a vast number of both laboratory and clinical studies were performed and published, with varying results. In the first study of this thesis a prospective clinical trial was performed at a public dental health clinic in Sweden. Twenty-five patients were provided with 40 copings of pure titanium, which were veneered with porcelain. After 2 years 36 of these crowns were evaluated and the patients were also interviewed regarding problems such as shooting pains or difficulties in cleaning around the teeth that were crowned. This evaluation

  7. In vitro toxicity evaluation of silver soldering, electrical resistance, and laser welding of orthodontic wires.

    PubMed

    Sestini, Silvia; Notarantonio, Laura; Cerboni, Barbara; Alessandrini, Carlo; Fimiani, Michele; Nannelli, Pietro; Pelagalli, Antonio; Giorgetti, Roberto

    2006-12-01

    The long-term effects of orthodontic appliances in the oral environment and the subsequent leaching of metals are relatively unknown. A method for determining the effects of various types of soldering and welding, both of which in turn could lead to leaching of metal ions, on the growth of osteoblasts, fibroblasts, and oral keratinocytes in vitro, is proposed. The effects of cell behaviour of metal wires on osteoblast differentiation, expressed by alkaline phosphatase (ALP) activity; on fibroblast proliferation, assayed by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulphophenil)-2H-tetrazolium-phenazine ethosulphate method; and on keratinocyte viability and migration on the wires, observed by scanning electron microscopy (SEM), were tested. Two types of commercially available wires normally used for orthodontic appliances, with a similar chemical composition (iron, carbon, silicon, chromium, molybdenum, phosphorus, sulphur, vanadium, and nitrogen) but differing in nickel and manganese content, were examined, as well as the joints obtained by electrical resistance welding, traditional soldering, and laser welding. Nickel and chromium, known as possible toxic metals, were also examined using pure nickel- and chromium-plated titanium wires. Segments of each wire, cut into different lengths, were added to each well in which the cells were grown to confluence. The high nickel and chromium content of orthodontic wires damaged both osteoblasts and fibroblasts, but did not affect keratinocytes. Chromium strongly affected fibroblast growth. The joint produced by electrical resistance welding was well tolerated by both osteoblasts and fibroblasts, whereas traditional soldering caused a significant (P < 0.05) decrease in both osteoblast ALP activity and fibroblast viability, and prevented the growth of keratinocytes in vitro. Laser welding was the only joining process well tolerated by all tested cells.

  8. ELECTRIC WELDING EQUIPMENT AND AUTOMATION OF WELDING IN CONSTRUCTION,

    DTIC Science & Technology

    WELDING , *ARC WELDING , AUTOMATION, CONSTRUCTION, INDUSTRIES, POWER EQUIPMENT, GENERATORS, POWER TRANSFORMERS, RESISTANCE WELDING , SPOT WELDING , MACHINES, AUTOMATIC, STRUCTURES, WIRING DIAGRAMS, USSR.

  9. Syllabus in Trade Welding.

    ERIC Educational Resources Information Center

    New York State Education Dept., Albany. Bureau of Secondary Curriculum Development.

    The syllabus outlines material for a course two academic years in length (minimum two and one-half hours daily experience) leading to entry-level occupational ability in several welding trade areas. Fourteen units covering are welding, gas welding, oxyacetylene welding, cutting, nonfusion processes, inert gas shielded-arc welding, welding cast…

  10. Composite thin-foil bandpass filter for EUV astronomy Titanium-antimony-titanium

    NASA Technical Reports Server (NTRS)

    Jelinsky, P.; Martin, C.; Kimble, R.; Bowyer, S.; Steele, G.

    1983-01-01

    Thin metallic foils of antimony and titanium have been investigated in an attempt to develop an EUV filter with a bandpass from 350 to 550 A. A composite filter has been developed composed of antimony sandwiched between two titanium foils. The transmissions of sample composite foils and of pure titanium foils from 130 to 1216 A are presented. The absorption coefficients of anatimony and titanium and the effect of titanium oxide on the transmission are derived. The composite filter has been found to be quite stable and mechanically rugged. Among other uses, the filter shows substantial promise for EUV astronomy.

  11. Composite thin-foil bandpass filter for EUV astronomy Titanium-antimony-titanium

    NASA Technical Reports Server (NTRS)

    Jelinsky, P.; Martin, C.; Kimble, R.; Bowyer, S.; Steele, G.

    1983-01-01

    Thin metallic foils of antimony and titanium have been investigated in an attempt to develop an EUV filter with a bandpass from 350 to 550 A. A composite filter has been developed composed of antimony sandwiched between two titanium foils. The transmissions of sample composite foils and of pure titanium foils from 130 to 1216 A are presented. The absorption coefficients of anatimony and titanium and the effect of titanium oxide on the transmission are derived. The composite filter has been found to be quite stable and mechanically rugged. Among other uses, the filter shows substantial promise for EUV astronomy.

  12. Wonder Weld

    SciTech Connect

    2012-01-01

    Engineers at the U.S. Department of Energy's Princeton Plasma Physics Laboratory are using the process shown here to create a super-strong weld for the upgrade of a key component of the Lab's experimental nuclear fusion reactor.

  13. Laser Welded versus Resistance Spot Welded Bone Implants: Analysis of the Thermal Increase and Strength

    PubMed Central

    Fornaini, Carlo; Meleti, Marco; Bonanini, Mauro; Lagori, Giuseppe; Vescovi, Paolo; Merigo, Elisabetta; Nammour, Samir

    2014-01-01

    Introduction. The first aim of this “ex vivo split mouth” study was to compare the thermal elevation during the welding process of titanium bars to titanium implants inserted in pig jaws by a thermal camera and two thermocouples. The second aim was to compare the strength of the joints by a traction test with a dynamometer. Materials and Methods. Six pigs' jaws were used and three implants were placed on each side of them for a total of 36 fixtures. Twelve bars were connected to the abutments (each bar on three implants) by using, on one side, laser welding and, on the other, resistance spot welding. Temperature variations were recorded by thermocouples and by thermal camera while the strength of the welded joint was analyzed by a traction test. Results. For increasing temperature, means were 36.83 and 37.06, standard deviations 1.234 and 1.187, and P value 0.5763 (not significant). For traction test, means were 195.5 and 159.4, standard deviations 2.00 and 2.254, and P value 0.0001 (very significant). Conclusion. Laser welding was demonstrated to be able to connect titanium implant abutments without the risk of thermal increase into the bone and with good results in terms of mechanical strength. PMID:25110731

  14. Workshop Report Advanced Welding Science for DoD Application: The Genesis of the Army Welding Microfactory Held in Golden, Colorado on 20-22 March 1991.

    DTIC Science & Technology

    1991-06-01

    Hardfacing (c) Low Cost Titanium Consumables (d) Flux and Electrode Coating Systems (e) High Performance Aluminum Consumables (f) Aluminum Filler...investigation. Aluminum metal matrix composite filler alloys need to be investigated for unique weld metal properties (1991). HARDFACING (22) Welded overlay

  15. Solid State Joining of Dissimilar Titanium Alloys

    NASA Astrophysics Data System (ADS)

    Morton, Todd W.

    Solid state joining of titanium via friction stir welding and diffusion bonding have emerged as enablers of efficient monolithic structural designs by the eliminations fasteners for the aerospace industry. As design complexity and service demands increase, the need for joints of dissimilar alloys has emerged. Complex thermomechanical conditions in friction stir weld joints and high temperature deformation behavior differences between alloys used in dissimilar joints gives rise to a highly variable flow pattern within a stir zone. Experiments performed welding Ti-6Al-4V to beta21S show that mechanical intermixing of the two alloys is the primary mechanism for the generation of the localized chemistry and microstructure, the magnitude of which can be directly related to pin rotation and travel speed weld parameters. Mechanical mixing of the two alloys is heavily influenced by strain rate softening phenomena, and can be used to manipulate weld nugget structure by switching which alloy is subjected to the advancing side of the pin. Turbulent mixing of a weld nugget and a significant reduction in defects and weld forces are observed when the beta21S is put on the advancing side of the weld where higher strain rates are present. Chemical diffusion driven by the heat of weld parameters is characterized using energy dispersive x-ray spectroscopy (EDS) and is shown to be a secondary process responsible for generating short-range chemical gradients that lead to a gradient of alpha particle structures. Diffusion calculations are inconsistent with an assumption of steady-state diffusion and show that material interfaces in the weld nugget evolve through the break-down of turbulent interface features generated by material flows. A high degree of recrystallization is seen throughout the welds, with unique, hybrid chemistry grains that are generated at material interfaces in the weld nugget that help to unify the crystal structure of dissimilar alloys. The degree of

  16. Welding method combining laser welding and MIG welding

    SciTech Connect

    Hamasaki, M.

    1985-03-26

    Welding of deep penetration is obtained in a sustrate by a method which comprises first melting the joint portion of the substrates by MIG welding and then focusing a laser beam in the bottom surface of a crater formed in consequence of the MIG welding thereby effecting laser welding of the crater.

  17. Welded Kimberlite?

    NASA Astrophysics Data System (ADS)

    van Straaten, B. I.; Kopylova, M. G.; Russell, J. K.; Scott Smith, B. H.

    2009-05-01

    Welding of pyroclastic deposits generally involves the sintering of hot glassy vesicular particles and requires the presence of a load and/or high temperatures. Welding can occur on various scales as observed in large welded pyroclastic flows, in small-volume agglutinated spatter rims, or as in coalesced clastogenic lava flows. In all these examples welding occurs mainly by reduction or elimination of porosity within the vesicular clasts and/or inter-clast pore space. The end result of welding in pyroclastic deposits is to produce dense, massive, coherent deposits. Here, we present a possible new end-member of the welding process: welding of non- vesicular pyroclasts in intra-crater kimberlite deposits. Kimberlite melt is a low-viscosity liquid carrying abundant crystals. Because of this, kimberlite eruptions generally produce non-vesicular pyroclasts. During welding, these pyroclast cannot deform by volume reduction to form typical fiamme. As a result, welding and compaction in kimberlites proceeds via the reduction of inter-clast pore space alone. The lack of porous pyroclasts limits the maximum amount of volumetric strain within pyroclastic kimberlite deposits to about 30%. This value is substantially lower than the limiting values for welding of more common felsic pyroclastic flows. The lower limit for volumetric strain in welded kimberlite deposits severely restricts the development of a fabric. In addition, pyroclastic kimberlite deposits commonly feature equant-shaped pyroclasts, and equant-shaped crystals. This, in turn, limits the visibility of the results of compaction and pore space reduction, as there are few deformable markers and elongate rigid markers that are able to record the strain during compaction. These features, together with the low viscosity of kimberlite magma and the stratigraphic position of these kimberlite deposits within the upper reaches of the volcanic conduit, call for careful interpretation of coherent-looking rocks in these

  18. Solar cell welded interconnection development program. [parallel gap and ultrasonic metal-metal bonding

    NASA Technical Reports Server (NTRS)

    Katzeff, J. S.

    1974-01-01

    Parallel gap welding and ultrasonic bonding techniques were developed for joining selected interconnect materials (silver, aluminum, copper, silver plated molybdenum and Kovar) to silver-titanium and aluminum contact cells. All process variables have been evaluated leading to establishment of optimum solar cell, interconnect, electrodes and equipment criteria for obtainment of consistent high quality welds. Applicability of nondestructive testing of solar cell welds has been studied. A pre-weld monitoring system is being built and will be utilized in the numerically controlled parallel gap weld station.

  19. Laser welding and syncristallization techniques comparison: "Ex vivo" study.

    PubMed

    Fornaini, Carlo; Meleti, Marco; Vescovi, Paolo; Merigo, Elisabetta; Rocca, Jean-Paul

    2013-12-30

    Stabilization of implant abutments through electric impulses at high voltage for a very short time (electrowelding) was developed in the Eighties. In 2009, the same procedure was performed through the use of laser (laser welding) The aim of this study is to compare electrowelding and laser welding for intra-oral implant abutments stabilization on "ex vivo models" (pig jaws). Six bars were welded with two different devices (Nd:YAG laser and Electrowelder) to eighteen titanium implant abutment inserted in three pig jaws. During the welding process, thermal increase was recorded, through the use of k-thermocouples, in the bone close to the implants. The strength of the welded joints was evaluated by a traction test after the removal of the implants. For temperature measurements a descriptive analysis and for traction test "values unpaired t test with Welch's correction" were performed: the significance level was set at P<0.05. Laser welding gives a lower thermal increase than Electrowelding at the bone close to implants (Mean: 1.97 and 5.27); the strength of laser welded joints was higher than that of Electrowelding even if nor statistically significant. (Mean: 184.75 and 168.29) CONCLUSION: Electrowelding seems to have no advantages, in term of thermal elevation and strength, while laser welding may be employed to connect titanium implants for immediate load without risks of thermal damage at surrounding tissues.

  20. Characterization of Defocused Electron Beams and Welds in Stainless Steel and Refractory Metals using the Enhanced Modified Faraday Cup Diagnostic

    SciTech Connect

    Elmer, J W

    2009-01-23

    As the first part of a project to compare new generation, continuous wave, laser welding technology to traditional electron beam welding technology, electron beam welds were made on commercially pure vanadium refractory metal and 21-6-9 austenitic stainless steel. The electron beam welds were made while employing EB diagnostics to fully characterize the beams so that direct comparisons could be made between electron beam and laser beams and the welds that each process produces.

  1. Particulate and gaseous emissions when welding aluminum alloys.

    PubMed

    Cole, Homer; Epstein, Seymour; Peace, Jon

    2007-09-01

    Fabrication and repair of aluminum components and structures commonly involves the use of electric arc welding. The interaction of the arc and the metal being welded generates ultraviolet radiation, metallic oxides, fumes, and gases. Aluminum is seldom used as the pure metal but is often alloyed with other metals to improve strength and other physical properties. Therefore, the exact composition of any emissions will depend on the welding process and the particular aluminum alloy being welded. To quantify such emissions, The Aluminum Association sponsored several studies to characterize arc welding emissions by the gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) processes for various combinations of base and filler alloys. In all cases, the tests were conducted under conditions that could be found in a production weld shop without forced ventilation. The concentrations of each analyte that a welder could be exposed to were greatly affected by the welding process, the composition of the base and filler alloys, the position of the welder, and the welding helmet. The results obtained can be used by employers to identify and control potential hazards associated with the welding of aluminum alloys and can provide the basis for hazard communication to employees involved in the welding of these alloys.

  2. Effect of Electromagnetic Stirring on Weld Pools.

    DTIC Science & Technology

    1983-10-01

    Cminue an reverse sde If neceewer mE identity b block nmber) GTAW Electromagnetic Agitation Titanium Thermal Gradient 20. A RACT (Continue en revers... GTAW Gas Tungsten Arc Welding V Voltage iv -- ’ -’y - -’ e - a + . - - . - CONVERSION FACTORS 1 -1/sin - 2.12 cfh I J - 5 (9F - 32) 1 cm - 0.394 in...carefully controlled and monitored conditions. The set of welds made to determine the effect of stirring frequency on grain size employed automated GTAW

  3. Designing shielded metal arc consumables for underwater wet welding in offshore applications

    SciTech Connect

    Sanchez-Osio, A.; Liu, S.; Olson, D.L.; Ibarra, S.

    1995-08-01

    The use of underwater wet welding for offshore repairs has been limited mainly because of porosity and low toughness in the resulting welds. With appropriate consumable design, however, it is possible to reduce porosity and to enhance weld metal toughness through microstructural refinement. New titanium and boron-based consumables have been developed with which high toughness acicular ferrite (AF) can be produced in underwater wet welds. Titanium, by means of oxide formation, promoted an increase in the amount of acicular ferrite in the weld metal, while boron additions decreased the amount of grain boundary ferrite (GBF), further improving the microstructure. Porosity reduction was possible through the addition of calcium carbonate at approximately 13 wt percent in the electrode coating. However, weld metal decarbonization also resulted with the addition of carbonate.

  4. Weld geometry strength effect in 2219-T87 aluminum

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.; Novak, H. L.; Mcilwain, M. C.

    1981-01-01

    A theory of the effect of geometry on the mechanical properties of a butt weld joint is worked out based upon the soft interlayer weld model. Tensile tests of 45 TIG butt welds and 6 EB beads-on-plate in 1/4-in. 2219-T87 aluminum plate made under a wide range of heat sink and power input conditions are analyzed using this theory. The analysis indicates that purely geometrical effects dominate in determining variations in weld joint strength with heat sink and power input. Variations in weld dimensions with cooling rate are significant as well as with power input. Weld size is suggested as a better indicator of the condition of a weld joint than energy input.

  5. Fusion welding studies using laser on Ti-SS dissimilar combination

    NASA Astrophysics Data System (ADS)

    Shanmugarajan, B.; Padmanabham, G.

    2012-11-01

    Laser welding investigations were carried out on dissimilar Ti-SS combination. The study is aimed to improve the weld strength and ductility by minimizing harmful intermetallics and taking advantage of high cooling rates in laser welding. Results of continuous wave 3.5 kW CO2 laser welding of totally dissimilar combination of Titanium and stainless steel (304) have been discussed. Bead on plate welding experiments were conducted to identify the laser welding parameters using depth of penetration as criteria. The welding of dissimilar combination has been attempted both autogenously and with interlayers such as Vanadium (V) and Tantalum (Ta) in the form of laser cladding as well as strip. Autogenous welds were carried out by varying the laser power, welding speed and position of the laser beam with respect to the joint centre. The resultant welds are characterized by macrostructure analysis, SEM/EDAX and XRD and as welded tensile test in UTM. The autogenous welds have exhibited extensive cracking even when welded at high speeds or by manipulating the beam position with respect to the joint. Similarly Vandaium as interlayer could not achieve crack free joint. A joint with 40 MPa strength could be made with Ta as interlayer. Results and analysis of these variants of laser welded joints are reported and discussed.

  6. Plasmonic welding of hybrid Au-ZnO nanostructure

    NASA Astrophysics Data System (ADS)

    Chen, Z. Y.; Yang, H. B.; Ghosh, P.; Li, Q.; Qiu, M.

    2017-06-01

    We report that 532 nm CW laser can be used to obtain non-wetting metal-semiconductor (Au-ZnO) Schottky heterojunctions by plasmonic welding. Single crystal Au and n-type ZnO nanowires are placed on gold (Au) and titanium (Ti) electrodes, respectively, and the junction welding is realized. The current-voltage (I-V) characteristic curve of the single Schottky rectifier is also measured.

  7. Process for synthesizing titanium carbide, titanium nitride and titanium carbonitride

    DOEpatents

    Koc, R.; Glatzmaier, G.C.

    1995-05-23

    A process is disclosed for synthesizing titanium carbide, titanium nitride or titanium carbonitride. The process comprises placing particles of titanium, a titanium salt or titanium dioxide within a vessel and providing a carbon-containing atmosphere within the vessel. The vessel is heated to a pyrolysis temperature sufficient to pyrolyze the carbon to thereby coat the particles with a carbon coating. Thereafter, the carbon-coated particles are heated in an inert atmosphere to produce titanium carbide, or in a nitrogen atmosphere to produce titanium nitride or titanium carbonitride, with the heating being of a temperature and time sufficient to produce a substantially complete solid solution.

  8. Process for synthesizing titanium carbide, titanium nitride and titanium carbonitride

    DOEpatents

    Koc, Rasit; Glatzmaier, Gregory C.

    1995-01-01

    A process for synthesizing titanium carbide, titanium nitride or titanium carbonitride. The process comprises placing particles of titanium, a titanium salt or titanium dioxide within a vessel and providing a carbon-containing atmosphere within the vessel. The vessel is heated to a pyrolysis temperature sufficient to pyrolyze the carbon to thereby coat the particles with a carbon coating. Thereafter, the carbon-coated particles are heated in an inert atmosphere to produce titanium carbide, or in a nitrogen atmosphere to produce titanium nitride or titanium carbonitride, with the heating being of a temperature and time sufficient to produce a substantially complete solid solution.

  9. Welding Curtains

    NASA Astrophysics Data System (ADS)

    1984-01-01

    Concept of transparent welding curtains made of heavy duty vinyl originated with David F. Wilson, President of Wilson Sales Company. In 1968, Wilson's curtains reduced glare of welding arc and blocked ultraviolet radiation. When later research uncovered blue light hazards, Wilson sought improvement of his products. He contracted Dr. Charles G. Miller and James B. Stephens, both of Jet Propulsion Laboratory (JPL), and they agreed to undertake development of a curtain capable of filtering out harmful irradiance, including ultraviolet and blue light and provide protection over a broad range of welding operation. Working on their own time, the JPL pair spent 3 years developing a patented formula that includes light filtering dyes and small particles of zinc oxide. The result was the Wilson Spectra Curtain.

  10. Welding of Vanadium, Tantalum, 304L and 21-6-9 Stainless Steels, and Titanium Alloys at Lawrence Livermore National Laboratory using a Fiber Delivered 2.2 kW Diode Pumped CW Nd:YAG Laser

    SciTech Connect

    Palmer, T; Elmer, J; Pong, R; Gauthier, M

    2006-06-16

    This report summarizes the results of a series of laser welds made between 2003 and 2005 at Lawrence Livermore National Laboratory (LLNL). The results are a compilation of several, previously unpublished, internal LLNL reports covering the laser welding of vanadium, tantalum, 304L stainless steel, 21-6-9 (Nitronic 40) steel, and Ti-6Al-4V. All the welds were made using a Rofin Sinar DY-022 diode pumped continuous wave Nd:YAG laser. Welds are made at sharp focus on each material at various power levels and travel speeds in order to provide a baseline characterization of the performance of the laser welder. These power levels are based on measurements of the output power of the laser system, as measured by a power meter placed at the end of the optics train. Based on these measurements, it appears that the system displays a loss of approximately 10% as the beam passes through the fiber optic cable and laser optics. Since the beam is delivered to the fixed laser optics through a fiber optic cable, the effects of fiber diameter are also briefly investigated. Because the system utilizes 1:1 focusing optics, the laser spot size at sharp focus generally corresponds to the diameter of the fiber with which the laser is delivered. Differences in the resulting weld penetration in the different materials system are prevalent, with the welds produced on the Nitronic 40 material displaying the highest depths (> 5 mm) and minimal porosity. A Primes focusing diagnostic has also been installed on this laser system and used to characterize the size and power density distribution of the beams as a function of both power and focus position. Further work is planned in which this focusing diagnostic will be used to better understand the effects of changes in beam properties on the resulting weld dimensions in these and other materials systems.

  11. Truss Assembly and Welding by Intelligent Precision Jigging Robots

    NASA Technical Reports Server (NTRS)

    Komendera, Erik; Dorsey, John T.; Doggett, William R.; Correll, Nikolaus

    2014-01-01

    This paper describes an Intelligent Precision Jigging Robot (IPJR) prototype that enables the precise alignment and welding of titanium space telescope optical benches. The IPJR, equipped with micron accuracy sensors and actuators, worked in tandem with a lower precision remote controlled manipulator. The combined system assembled and welded a 2 m truss from stock titanium components. The calibration of the IPJR, and the difference between the predicted and the truss dimensions as-built, identified additional sources of error that should be addressed in the next generation of IPJRs in 2D and 3D.

  12. Narrow gap laser welding

    DOEpatents

    Milewski, John O.; Sklar, Edward

    1998-01-01

    A laser welding process including: (a) using optical ray tracing to make a model of a laser beam and the geometry of a joint to be welded; (b) adjusting variables in the model to choose variables for use in making a laser weld; and (c) laser welding the joint to be welded using the chosen variables.

  13. Narrow gap laser welding

    DOEpatents

    Milewski, J.O.; Sklar, E.

    1998-06-02

    A laser welding process including: (a) using optical ray tracing to make a model of a laser beam and the geometry of a joint to be welded; (b) adjusting variables in the model to choose variables for use in making a laser weld; and (c) laser welding the joint to be welded using the chosen variables. 34 figs.

  14. Weld pool oscillation during pulsed GTA welding

    SciTech Connect

    Aendenroomer, A.J.R.; Ouden, G. den

    1996-12-31

    This paper deals with weld pool oscillation during pulsed GTA welding and with the possibility to use this oscillation for in-process control of weld penetration. Welding experiments were carried out under different welding conditions. During welding the weld pool was triggered into oscillation by the normal welding pulses or by extra current pulses. The oscillation frequency was measured both during the pulse time and during the base time by analyzing the arc voltage variation using a Fast Fourier Transformation program. Optimal results are obtained when full penetration occurs during the pulse time and partial penetration during the base time. Under these conditions elliptical overlapping spot welds are formed. In the case of full penetration the weld pool oscillates in a low frequency mode (membrane oscillation), whereas in the case of partial penetration the weld pool oscillates in a high frequency mode (surface oscillation). Deviation from the optimal welding conditions occurs when high frequency oscillation is observed during both pulse time and base time (underpenetration) or when low frequency oscillation is observed during both pulse time and base time (overpenetration). In line with these results a penetration sensing system with feedback control was designed, based on the criterion that optimal weld penetration is achieved when two peaks are observed in the frequency distribution. The feasibility of this sensing system for orbital tube welding was confirmed by the results of experiments carried out under various welding conditions.

  15. Electroslag and electrogas welding

    NASA Technical Reports Server (NTRS)

    Campbell, H. C.

    1972-01-01

    These two new joining methods perform welding in the vertical position, and therein lies the secret of their impressive advantages in material handling, in weld preparation, in welding speed, in freedom from distortion, and in weld soundness. Once the work has been set in the proper vertical position for welding, no further plate handling is required. The molten filler metal is held in place by copper shoes or dams, and the weld is completed in one pass.

  16. Welding processes and practices

    SciTech Connect

    Koellhoffer, L.; Manz, A.F.; Hornberger, G.

    1987-01-01

    Each section begins with basic process theory and moves on to practical exercises that become increasingly more difficult. Among the many processes and practices covered are: the materials and mechanical factors, basic positions and joints, oxyfuel gas welding, oxyacetylene welding of carbon steel, shielded metal arc welding, flux-colored arc welding, and gas tungsten arc welding. Discusses the advantages and disadvantages of welding, and presents trouble-shooting techniques.

  17. Texture Development in Friction Stir Welds

    DTIC Science & Technology

    2011-01-01

    distor- tion). Friction stir welding was initially developed for aluminium alloys, but has since been demonstrated for copper, iron, titanium and...textures. The predominant mode of deformation, particularly in regions near the tool, is simple shear, as confirmed in previous FSW studies of aluminium ...alloys.3–8 It has been demonstrated that continuous dynamic recrystallisation, i.e. the concurrent processes of deformation and dynamic recovery, is

  18. The influence of consumable composition and solidification on inclusion formation and growth in low carbon steel underwater wet welds

    SciTech Connect

    Sanchez-Osio, A.; Liu, S.

    1995-02-01

    The use of underwater wet welding for offshore repairs has been limited mainly because of porosity in the resulting welds. With appropriate consumable design, however, it is possible to enhance weld metal toughness and reduce porosity. Surface and underwater wet welds, obtained with E6013 grade electrodes modified with systematic titanium and boron additions, were prepared and analyzed to explain, in terms of the fundamentals of inclusion formation during weld solidification, any increase in acicular ferrite. It was demonstrated that in underwater wet welding, over 60% vol. acicular ferrite can be obtained, through titanium and boron additions to the electrode covering. The presence of titanium resulted in the formation of inclusions which assisted the formation of acicular ferrite in the underwater welds and countered the rapid quenching effect of the underwater environment. Boron additions decreased the amount of grain boundary ferrite, further improving the microstructure. It was shown that the weld metal titanium and boron compositional ranges for acicular ferrite maximization varied with the heat input and the cooling rate. Porosity reduction was possible through the addition of calcium carbonate at approximately 13% wt. in the flux covering. However, weld metal decarburization also occurred with the addition. The Zener diameter approach was used to relate the inclusion size and austenite grain size, and to explain the resulting microstructure.

  19. Effect of joint design and welding type on the flexural strength and weld penetration of Ti-6Al-4V alloy bars.

    PubMed

    Simamoto Júnior, Paulo Cézar; Resende Novais, Veridiana; Rodrigues Machado, Asbel; Soares, Carlos José; Araújo Raposo, Luís Henrique

    2015-05-01

    Framework longevity is a key factor for the success of complete-arch prostheses and commonly depends on the welding methods. However, no consensus has been reached on the joint design and welding type for improving framework resistance. The purpose of this study was to assess the effect of different joint designs and welding methods with tungsten inert gas (TIG) or laser to join titanium alloy bars (Ti-6Al-4V). Seventy titanium alloy bar specimens were prepared (3.18 mm in diameter × 40.0 mm in length) and divided into 7 groups (n=10): the C-control group consisting of intact specimens without joints and the remaining 6 groups consisting of specimens sectioned perpendicular to the long-axis and rejoined using an I-, X30-, or X45-shaped joint design with TIG welding (TI, TX30, and TX45) or laser welding (LI, LX30, and LX45). The specimens were tested with 3-point bending. The fracture surfaces were first evaluated with stereomicroscopy to measure the weld penetration area and then analyzed with scanning electron microscopy (SEM). The data were statistically analyzed with 2-way ANOVA and the Tukey post hoc test, 1-way ANOVA and the Dunnett test, and the Pearson correlation test (α=.05). Specimens from the X30 and X45 groups showed higher flexural strength (P<.05) and welded area (P<.05) than specimens from the I groups, regardless of the welding type. TIG welded groups showed significantly higher flexural strength than the laser groups (P<.05), regardless of the joint design. TIG welding also resulted in higher welded areas than laser welding for the I-shaped specimens. No significant differences were found for the weld penetration area in the X45 group, either for laser or TIG welding. SEM analysis showed more pores at the fracture surfaces of the laser specimens. Fracture surfaces indicative of regions of increased ductility were detected for the TIG specimens. TIG welding resulted in higher flexural strength for the joined titanium specimens than laser welding

  20. Titanium/titanium nitride temporomandibular joint prosthesis: historical background and a six-year clinical review.

    PubMed

    Bütow, K W; Blackbeard, G A; van der Merwe, A E

    2001-08-01

    The titanium/titanium nitride temporomandibular joint (TTN-TMJ) prosthesis, for the combined replacement of both the joint and the glenoid fossa, was developed in 1992 and introduced clinically in 1994. This joint prosthesis is manufactured from pure titanium and the condylar surfaces, as well as the fossa, are coated with titanium nitride for hardening of the contact surfaces. In two different research projects, the joint were first placed in experimental animals, before they were successfully placed in human subjects. Twenty seven joint prostheses used in human subjects have been analysed for this review.

  1. Modification of Structure and Strength Properties of Permanent Joints Under Laser Beam Welding with Application of Nanopowder Modifiers

    NASA Astrophysics Data System (ADS)

    Cherepanov, A. N.; Orishich, A. M.; Malikov, A. G.; Ovcharenko, V. E.

    2016-08-01

    In the paper we present the results of experimental study of specially prepared nanosize metal-ceramic compositions impact upon structure, microhardness and mechanical properties of permanent joints produced by laser-beam welding of steel and titanium alloy plates.

  2. Weld pool phenomena

    SciTech Connect

    David, S.A.; Vitek, J.M.; Zacharia, T.; DebRoy, T.

    1994-09-01

    During welding, the composition, structure and properties of the welded structure are affected by the interaction of the heat source with the metal. The interaction affects the fluid flow, heat transfer and mass transfer in the weld pool, and the solidification behavior of the weld metal. In recent years, there has been a growing recognition of the importance of the weld pool transport processes and the solid state transformation reactions in determining the composition, structure and properties of the welded structure. The relation between the weld pool transport processes and the composition and structure is reviewed. Recent applications of various solidification theories to welding are examined to understand the special problems of weld metal solidification. The discussion is focussed on the important problems and issues related to weld pool transport phenomena and solidification. Resolution of these problems would be an important step towards a science based control of composition, structure and properties of the weld metal.

  3. Friction plug welding

    NASA Technical Reports Server (NTRS)

    Takeshita, Riki (Inventor); Hibbard, Terry L. (Inventor)

    2001-01-01

    Friction plug welding (FPW) usage is advantageous for friction stir welding (FSW) hole close-outs and weld repairs in 2195 Al--Cu--Li fusion or friction stir welds. Current fusion welding methods of Al--Cu--Li have produced welds containing varied defects. These areas are found by non-destructive examination both after welding and after proof testing. Current techniques for repairing typically small (<0.25) defects weaken the weldment, rely heavily on welders' skill, and are costly. Friction plug welding repairs increase strength, ductility and resistance to cracking over initial weld quality, without requiring much time or operator skill. Friction plug welding while pulling the plug is advantageous because all hardware for performing the weld can be placed on one side of the workpiece.

  4. WELDING APPARATUS

    DOEpatents

    Correy, T.B.; DeWitt, D.E.; Nelson, I.V.

    1963-04-23

    This patent covers an arrangement for replacing air in a welding chamber with an inert gas. This operation usually is time-consuming because of the tendency of the inert gas to mix with the air being removed from the welding chamber. The chamber is open at the bottom and has at its top a cover and a porous plate a little below the cover. The inert gas is admitted to the chamber through two screened openings in the cover. On passing through the porous plate, the gas acts as a piston extending across the chamber and moving downwardly to expel the air through the lower open end of the chamber, with a minimum of mixing with the air being expelled. (AEC)

  5. WELDING PROCESS

    DOEpatents

    Zambrow, J.; Hausner, H.

    1957-09-24

    A method of joining metal parts for the preparation of relatively long, thin fuel element cores of uranium or alloys thereof for nuclear reactors is described. The process includes the steps of cleaning the surfaces to be jointed, placing the sunfaces together, and providing between and in contact with them, a layer of a compound in finely divided form that is decomposable to metal by heat. The fuel element members are then heated at the contact zone and maintained under pressure during the heating to decompose the compound to metal and sinter the members and reduced metal together producing a weld. The preferred class of decomposable compounds are the metal hydrides such as uranium hydride, which release hydrogen thus providing a reducing atmosphere in the vicinity of the welding operation.

  6. Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur C., Jr.

    2008-01-01

    Friction stir welding (FSW) is a solid state welding process invented in 1991 at The Welding Institute in the United Kingdom. A weld is made in the FSW process by translating a rotating pin along a weld seam so as to stir the sides of the seam together. FSW avoids deleterious effects inherent in melting and promises to be an important welding process for any industries where welds of optimal quality are demanded. This article provides an introduction to the FSW process. The chief concern is the physical effect of the tool on the weld metal: how weld seam bonding takes place, what kind of weld structure is generated, potential problems, possible defects for example, and implications for process parameters and tool design. Weld properties are determined by structure, and the structure of friction stir welds is determined by the weld metal flow field in the vicinity of the weld tool. Metal flow in the vicinity of the weld tool is explained through a simple kinematic flow model that decomposes the flow field into three basic component flows: a uniform translation, a rotating solid cylinder, and a ring vortex encircling the tool. The flow components, superposed to construct the flow model, can be related to particular aspects of weld process parameters and tool design; they provide a bridge to an understanding of a complex-at-first-glance weld structure. Torques and forces are also discussed. Some simple mathematical models of structural aspects, torques, and forces are included.

  7. Characterization of In-Situ Alloyed and Additively Manufactured Titanium Aluminides

    NASA Astrophysics Data System (ADS)

    Ma, Yan; Cuiuri, Dominic; Hoye, Nicholas; Li, Huijun; Pan, Zengxi

    2014-12-01

    Titanium aluminide components were fabricated using in-situ alloying and layer additive manufacturing based on the gas tungsten arc welding process combined with separate wire feeding of titanium and aluminum elements. The new fabrication process promises significant time and cost saving in comparison to traditional methods. In the present study, issues such as processing parameters, microstructure, and properties are discussed. The results presented here demonstrate the potential to produce full density titanium aluminide components directly using the new technique.

  8. Investigation of Conditions of Titanium Carbonization - IV

    NASA Technical Reports Server (NTRS)

    Meerson, G. A.; Lipkes, Y. M.

    1949-01-01

    In a previous paper, results are presented of accurate investigations of the processes of titanium carbonization and the succeeding titanium carbide decarbonization as related to the phenomenon of the graphitization of soot by heating at a constant temperature in atmospheres of pure hydrogen and carbon monoxide. These tests showed that the processes of titanium carbonization-decarbonization in an atmosphere of pure gases without nitrogen proceed in the same direction as the analogous processes under the conditions of the production furnace. In this case, however, the presence of admixtures of nitrogen changes the quantitative results of the decarbonization process. Thermodynamic computations confirming the results of previous tests conducted at atmospheric pressure and additional tests of titanium carbonization at lowered pressures are presented herein.

  9. Strain aging and toughness characteristics of ferritic weld metals

    SciTech Connect

    Kocak, M.; Petrovski, B.; Evans, G.M.

    1994-12-31

    The effects of varying nitrogen, titanium, boron, and aluminum contents on the as-deposited, stress-relieved, and artificially strain-aged shielded metal arc weld (SMAW) metal properties have been studied. There are still uncertainties concerning the exact role of each element and interactions between these elements with respect to the weld metal microstructure, strain aging and fracture properties. Therefore, systematic additions of titanium (in the range of 5 ppm to 500 ppm), boron (5 ppm to 200 ppm), aluminum (5 ppm to 560 ppm) and nitrogen were made to obtain various amounts of acicular ferrite and different microstructures which lead to the varying fracture behaviors and sensitivity to the strain aging. Increasing boron content also leads to an increase of the Charpy-V transition temperature with varying sensitivity to nitrogen content. Results indicate that as toughness of the as-deposited weld metal containing 40 ppm boron s much more sensitive to nitrogen content than the weld deposits contain 160 ppm boron. A similar trend has also been seen with the addition of 160 ppm aluminum to the weld metal while a change of titanium content did not cause such a significant change. In summary, present paper rigorously reviews the results of this extensive research program to develop a mechanistic understanding of the microalloying system (Ti, B and Al) on the strain aging and fracture toughness properties (Charpy-V and CTOD) of the multipass ferritic weldments.

  10. Small-scale explosive seam welding. [using ribbon explosive encased in lead sheath

    NASA Technical Reports Server (NTRS)

    Bement, L. J.

    1972-01-01

    A unique small scale explosive seam welding technique is reported that has successfully joined a variety of aluminum alloys and alloy combinations in thicknesses to 0.125 inch, as well as titanium in thicknesses to 0.056 inch. The explosively welded joints are less than one-half inch in width and apparently have no long length limitation. The ribbon explosive developed in this study contains very small quantities of explosive encased in a flexible thin lead sheath. The evaluation and demonstration of this welding technique was accomplished in three phases: evaluation and optimization of ten major explosive welding variables, the development of four weld joints, and an applicational analysis which included photomicrographs, pressure integrity tests, vacuum effects, and fabrication of some potentially useful structures in aluminum and titanium.

  11. Titanium-Oxygen Reactivity Study

    NASA Technical Reports Server (NTRS)

    Chafey, J. E.; Scheck, W. G.; Witzell, W. E.

    1962-01-01

    A program has been conducted at Astronautics to investigate the likelihood of occurrence of the catastrophic oxidation of titanium alloy sheet under conditions which simulate certain cases of accidental failure of the metal while it is in contact with liquid or gaseous oxygen. Three methods of fracturing the metal were used; they consisted of mechanical puncture, tensile fracture of welded joints, and perforation by very high velocity particles. The results of the tests which have been conducted provide further evidence of the reactivity of titanium with liquid and gaseous oxygen. The evidence indicates that the rapid fracturing of titanium sheet while it is in contact with oxygen initiates the catastrophic oxidation reaction. Initiation occurred when the speed of the fracture was some few feet per second, as in both the drop-weight puncture tests and the static tensile fracture tests of welded joints, as well as when the speed was several thousand feet per second, as in the simulated micrometeoroid penetration tests. The slow propagation of a crack, however, did not initiate the reaction. It may logically be concluded that the localized frictional heat of rapid fracture and/or spontaneous oxidation (exothermic) of minute particles emanating from the fracture cause initiation of the reaction. Under conditions of slow fracture, however, the small heat generated may be adequately dissipated and the reaction is not initiated. A portion of the study conducted consisted of investigating various means by which the reaction might be retarded or prevented. Providing a "barrier" at the titanium-oxygen interface consisting of either aluminum metal or a coating of a petroleum base corrosion inhibitor appeared to be only partially effective in retarding the reaction. The accidental puncturing or similar rupturing of thin-walled pressurized oxygen tanks on missiles and space vehicle will usually constitute loss of function, and may sometimes cause their catastrophic destruction

  12. Introduction to Welding.

    ERIC Educational Resources Information Center

    Fortney, Clarence; Gregory, Mike

    This curriculum guide provides six units of instruction on basic welding. Addressed in the individual units of instruction are the following topics: employment opportunities for welders, welding safety and first aid, welding tools and equipment, basic metals and metallurgy, basic math and measuring, and procedures for applying for a welding job.…

  13. Weld-Bead Shaver

    NASA Technical Reports Server (NTRS)

    Guirguis, Kamal; Price, Daniel S.

    1990-01-01

    Hand-held power tool shaves excess metal from inside circumference of welded duct. Removes excess metal deposited by penetration of tungsten/inert-gas weld or by spatter from electron-beam weld. Produces smooth transition across joint. Easier to use and not prone to overshaving. Also cuts faster, removing 35 in. (89 cm) of weld bead per hour.

  14. Decreasing biotoxicity of fume particles produced in welding process.

    PubMed

    Yu, Kuei-Min; Topham, Nathan; Wang, Jun; Kalivoda, Mark; Tseng, Yiider; Wu, Chang-Yu; Lee, Wen-Jhy; Cho, Kuk

    2011-01-30

    Welding fumes contain heavy metals, such as chromium, manganese, and nickel, which cause respiratory diseases and cancer. In this study, a SiO(2) precursor was evaluated as an additive to the shielding gas in an arc welding process to reduce the biotoxicity caused by welding fume particles. Transmission electron micrographic images show that SiO(2) coats on the surface of welding fume particles and promotes particle agglomeration. Energy dispersive X-ray spectroscopy further shows that the relative amount of silicon in these SiO(2)-coated agglomerates is higher than in baseline agglomerates. In addition, Escherichia coli (E. coli) exposed to different concentrations of pure SiO(2) particles generated from the arc welding process exhibits similar responses, suggesting that SiO(2) does not contribute to welding fume particle toxicity. The trend of E. coli growth in different concentrations of baseline welding fume particle shows the most significant inhibition occurs in higher exposure concentrations. The 50% lethal logarithmic concentrations for E. coli in arc welding particles of baseline, 2%, and 4.2% SiO(2) precursor additives were 823, 1605, and 1800 mg/L, respectively. Taken together, these results suggest that using SiO(2) precursors as an additive to arc welding shielding gas can effectively reduce the biotoxicity of welding fume.

  15. Laser welding in space

    NASA Technical Reports Server (NTRS)

    Kaukler, W. F.; Workman, G. L.

    1991-01-01

    Autogenous welds in 304 stainless steel were performed by Nd-YAG laser heating in a simulated space environment. Simulation consists of welding on the NASA KC-135 aircraft to produce the microgravity and by containing the specimen in a vacuum chamber. Experimental results show that the microgravity welds are stronger, harder in the fusion zone, have deeper penetration and have a rougher surface rippling of the weld pool than one-g welds. To perform laser welding in space, a solar-pumped laser concept that significantly increases the laser conversion efficiency and makes welding viable despite the limited power availability of spacecraft is proposed.

  16. Assessment of weld quality of aerospace grade metals by using ultrasonic matrix phased array technology

    NASA Astrophysics Data System (ADS)

    Na, Jeong K.; Gleeson, Sean T.

    2014-03-01

    Advantages of two dimensional electronic ultrasonic beam focusing, steering and scanning with the matrix phased array (MPA) technology has been used to visualize the conditions of resistance spot welds in auto vehicle grade advanced high strength steel carbon steels nondestructively. Two of the commonly used joining techniques, resistance spot welding and resistance seam welding, for thin aerospace grade plates made of aluminum, titanium, and stainless steels have also been inspected with the same MPA NDE system. In this study, a detailed discussions of the current MPA based ultrasonic real time imaging methodology has been made followed by some of the NDT results obtained with various welded test coupons.

  17. Application of titanium materials to vacuum chambers and components

    NASA Astrophysics Data System (ADS)

    Kurisu, H.; Ishizawa, K.; Yamamoto, S.; Hesaka, M.; Saito, Y.

    2008-03-01

    This paper describes the outgassing properties of titanium materials, and development of vacuum chambers and components for practical UHV/XHV systems. The mechano-chemically polished and the chemically polished titanium materials have a smooth surface and a thin (<= 10 nm) oxide surface layer, which showed extremely low outgassing rate below 10-12 Pams-1 after baking process. In order to fabricate practical vacuum systems welding, metallizing and brazing processes were optimized, and complex shaped vacuum chambers and various vacuum components such as a bellows, valve, electric feedthrough and ceramic duct with titanium sleeve were fabricated. Sufficient mechanical properties and durability were obtained for practical use.

  18. Welding properties of thin steel sheets by laser-arc hybrid welding: laser focused arc welding

    NASA Astrophysics Data System (ADS)

    Ono, Moriaki; Shinbo, Yukio; Yoshitake, Akihide; Ohmura, Masanori

    2003-03-01

    Laser-arc hybrid welding combines the laser and arc welding processes to provide advantages not found in either. This process can weld lapped steel sheets that have a larger gap than is possible with laser welding. Blowholes form when lap-welding zinc-coated steel sheets because of the zinc that is vaporized. The laser-arc hybrid welding process can lap-weld zinc-coated steel sheets without causing blowholes. The welding speed of laser-arc hybrid welding is nearly equivalent to that of laser welding. Laser-arc hybrid welding produces high-quality lap joints and is ideal for assembly welding of automotive parts.

  19. Advanced Welding Applications

    NASA Technical Reports Server (NTRS)

    Ding, Robert J.

    2010-01-01

    Some of the applications of advanced welding techniques are shown in this poster presentation. Included are brief explanations of the use on the Ares I and Ares V launch vehicle and on the Space Shuttle Launch vehicle. Also included are microstructural views from four advanced welding techniques: Variable Polarity Plasma Arc (VPPA) weld (fusion), self-reacting friction stir welding (SR-FSW), conventional FSW, and Tube Socket Weld (TSW) on aluminum.

  20. The Kinetics of Phase Transformation in Welds

    SciTech Connect

    Elmer, J W; Wong, J; Palmer, T

    2002-02-06

    The fundamentals of welding-induced phase transformations in metals and alloys are being investigated using a combination of advanced synchrotron based experimental methods and modem computational science tools. In-situ experimental methods have been developed using a spatially resolved x-ray probe to enable direct observations of phase transformations under the real non- isothermal conditions experienced during welding. These experimental techniques represent a major step forward in the understanding of phase transformations that occur during welding, and are now being used to aid in the development of models to predict microstructural evolution under the severe temperature gradients, high peak temperatures and rapid thermal fluctuations characteristic of welds. Titanium alloys, stainless steels and plain carbon steels are currently under investigation, and the phase transformation data being obtained here cannot be predicted or measured using conventional metallurgical approaches. Two principal synchrotron-based techniques have been developed and refined for in-situ investigations of phase transformation dynamics in the heat-affected zone (HAZ) and fusion zone (FZ) of welds: Spatially Resolved X-Ray Diffraction (SRXRD) and Time Resolved X-Ray Diffraction (TRXRD). Both techniques provide real-time observations of phases that exist during welding, and both have been developed at the Stanford Synchrotron Radiation Laboratory (SSRL) using a high flux wiggler beam line. The SRXRD technique enables direct observations of the phases existing in the HAZ of quasi-stationary moving arc welds, and is used to map the HAZ phases by sequentially jogging the weld with respect to the x-ray beam while taking x-ray diffraction (XRD) patterns at each new location. These spatially resolved XRD patterns are collected in linear traverses perpendicular to the direction of weld travel. The XRD data contained in multiple traverses is later compiled to produce an areal map of the phases

  1. Stress corrosion cracking of titanium alloys

    NASA Technical Reports Server (NTRS)

    Statler, G. R.; Spretnak, J. W.; Beck, F. H.; Fontana, M. G.

    1974-01-01

    The effect of hydrogen on the properties of metals, including titanium and its alloys, was investigated. The basic theories of stress corrosion of titanium alloys are reviewed along with the literature concerned with the effect of absorbed hydrogen on the mechanical properties of metals. Finally, the basic modes of metal fracture and their importance to this study is considered. The experimental work was designed to determine the effects of hydrogen concentration on the critical strain at which plastic instability along pure shear directions occurs. The materials used were titanium alloys Ti-8Al-lMo-lV and Ti-5Al-2.5Sn.

  2. Characterisation of fume from hyperbaric welding operations

    NASA Astrophysics Data System (ADS)

    Ross, John A. S.; Semple, Sean; Duffin, Rodger; Kelly, Frank; Seldmann, Joerg; Raab, Andrea

    2009-02-01

    We report preliminary work characterising dust from hyperbaric welding trials carried out at increased pressure in a helium and oxygen atmosphere. Particle size and concentration were measured during welding. Samples for quartz and metal analysis and toxicity assessment were taken from a filter in the local fume extraction system. The residue of dust after metal extraction by nitric acid in hydrogen peroxide predominantly a non-metallic white powder assumed to be dust from welding rod coatings and thermal insulation material. Metallic analysis showed predominantly calcium, from the welding rod coating, and period 4 transition metals such as iron, manganese, magnesium and titanium (inductively coupled mass spectrometry, Agilent 7500c). The presence of zirconium indicated a contribution from grinding. The fume was nanoparticulate in nature with a mean particle diameter of 20-30 nm (MSI Inc WPS 1000XP). It showed an intermediate level of oxidative potential regarding the low-molecular weight respiratory tract lining fluid antioxidants ascorbate and glutathione and caused release of the inflammatory marker IL-8 in a human lung A 549 epithelial cell culture with no indication of cytotoxicity. The study findings have strong implications for the measurement techniques needed to assess fume exposure in hyperbaric welding and the provision of respiratory protection.

  3. Titanium Cranioplasty

    PubMed Central

    Gordon, D. S.; Blair, G. A. S.

    1974-01-01

    The technique of repairing defects of the skull with titanium is described. The skull contour can be accurately reproduced. The technique is simpler than wiring or suturing methods. The material is inert, radiolucent, and rigid. ImagesFIG. 1FIG. 2FIG. 3FIG. 5FIG. 6FIG. 7 PMID:4834099

  4. The Molybdenum titanium Phase Diagram Evaluated from Ab initio Calculations

    DTIC Science & Technology

    2016-10-07

    between Titanium- Tantalum Alloy and Pure Titanium for Biomedical Applications, Mater. Trans. 48-3 (2007) 380-384. 8 E. B. Taddei, V. A. R. Henriques, C...surgical implant applications", Nov 2013 (originally approved in 2011). 13 L. Kaufman, Coupled thermochemical and phase diagram data for tantalum based...S. Barzilai, C. Toher, S. Curtarolo, O. Levy, Evaluation of the tantalum -titanium phase diagram from

  5. Television Monitoring System for Welding

    NASA Technical Reports Server (NTRS)

    Vallow, K.; Gordon, S.

    1986-01-01

    Welding process in visually inaccessible spots viewed and recorded. Television system enables monitoring of welding in visually inaccessible locations. System assists welding operations and provide video record, used for weld analysis and welder training.

  6. Television Monitoring System for Welding

    NASA Technical Reports Server (NTRS)

    Vallow, K.; Gordon, S.

    1986-01-01

    Welding process in visually inaccessible spots viewed and recorded. Television system enables monitoring of welding in visually inaccessible locations. System assists welding operations and provide video record, used for weld analysis and welder training.

  7. Deflection load characteristics of laser-welded orthodontic wires.

    PubMed

    Watanabe, Etsuko; Stigall, Garrett; Elshahawy, Waleed; Watanabe, Ikuya

    2012-07-01

    To compare the deflection load characteristics of homogeneous and heterogeneous joints made by laser welding using various types of orthodontic wires. Four kinds of straight orthodontic rectangular wires (0.017 inch × 0.025 inch) were used: stainless-steel (SS), cobalt-chromium-nickel (Co-Cr-Ni), beta-titanium alloy (β-Ti), and nickel-titanium (Ni-Ti). Homogeneous and heterogeneous end-to-end joints (12 mm long each) were made by Nd:YAG laser welding. Two types of welding methods were used: two-point welding and four-point welding. Nonwelded wires were also used as a control. Deflection load (N) was measured by conducting the three-point bending test. The data (n  =  5) were statistically analyzed using analysis of variance/Tukey test (P < .05). The deflection loads for control wires measured were as follows: SS: 21.7 ± 0.8 N; Co-Cr-Ni: 20.0 ± 0.3 N; β-Ti: 13.9 ± 1.3 N; and Ni-Ti: 6.6 ± 0.4 N. All of the homogeneously welded specimens showed lower deflection loads compared to corresponding control wires and exhibited higher deflection loads compared to heterogeneously welded combinations. For homogeneous combinations, Co-Cr-Ni/Co-Cr-Ni showed a significantly (P < .05) higher deflection load than those of the remaining homogeneously welded groups. In heterogeneous combinations, SS/Co-Cr-Ni and β-Ti/Ni-Ti showed higher deflection loads than those of the remaining heterogeneously welded combinations (significantly higher for SS/Co-Cr-Ni). Significance (P < .01) was shown for the interaction between the two factors (materials combination and welding method). However, no significant difference in deflection load was found between four-point and two-point welding in each homogeneous or heterogeneous combination. Heterogeneously laser-welded SS/Co-Cr-Ni and β-Ti/Ni-Ti wires provide a deflection load that is comparable to that of homogeneously welded orthodontic wires.

  8. Laser weld jig

    DOEpatents

    Van Blarigan, Peter; Haupt, David L.

    1982-01-01

    A system is provided for welding a workpiece (10, FIG. 1) along a predetermined weld line (12) that may be of irregular shape, which includes the step of forming a lip (32) on the workpiece to extend parallel to the weld line, and moving the workpiece by engaging the lip between a pair of rotatable members (34, 36). Rotation of one of the members at a constant speed, causes the workpiece to move so that all points on the weld line sequentially pass a fixed point in space (17) at a constant speed, so that a laser welding beam can be directed at that fixed point to form a weld along the weld line. The workpiece can include a reuseable jig (24) forming the lip, and with the jig constructed to detachably hold parts (22, 20) to be welded at a position wherein the weld line of the parts extends parallel to the lip on the jig.

  9. Welded solar cell interconnection

    NASA Technical Reports Server (NTRS)

    Stofel, E. J.; Browne, E. R.; Meese, R. A.; Vendura, G. J.

    1982-01-01

    The efficiency of the welding of solar-cell interconnects is compared with the efficiency of soldering such interconnects, and the cases in which welding may be superior are examined. Emphasis is placed on ultrasonic welding; attention is given to the solar-cell welding machine, the application of the welding process to different solar-cell configurations, producibility, and long-life performance of welded interconnects. Much of the present work has been directed toward providing increased confidence in the reliability of welding using conditions approximating those that would occur with large-scale array production. It is concluded that there is as yet insufficient data to determine which of three methods (soldering, parallel gap welding, and ultrasonic welding) provides the longest-duration solar panel life.

  10. Intelligent Welding Controller

    NASA Technical Reports Server (NTRS)

    Cook, George E.; Kumar, Ramaswamy; Prasad, Tanuji; Andersen, Kristinn; Barnett, Robert J.

    1989-01-01

    Control system adapts to changing design requirements and operating conditions. Proposed control system for gas/tungsten arc welding requires only that operator specifies such direct parameters of welds as widths and depths of penetration. In control system for robotic welder, components and functions intimately connected with welding process assigned to controller domain. More general functions assigned to supervisor domain. Initial estimate of indirect parameters of welding process applied to system only at beginning of weld (t=0); after start of welding, outputs from multivariable controller takes place of estimate.

  11. Fusion welding process

    DOEpatents

    Thomas, Kenneth C.; Jones, Eric D.; McBride, Marvin A.

    1983-01-01

    A process for the fusion welding of nickel alloy steel members wherein a ferrite containing pellet is inserted into a cavity in one member and melted by a welding torch. The resulting weld nugget, a fusion of the nickel containing alloy from the members to be welded and the pellet, has a composition which is sufficiently low in nickel content such that ferrite phases occur within the weld nugget, resulting in improved weld properties. The steel alloys encompassed also include alloys containing carbon and manganese, considered nickel equivalents.

  12. Effect of sulfur and oxygen on weld penetration of high-purity austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Aidun, D. K.; Martin, S. A.

    1997-08-01

    Convective flow during arc welding depends upon the surface tension gradient (dy/dT, Marangoni flow), buoyancy, arc drag force, electromagnetic force, shielding gas, and the viscosity of the melt. The Marangoni and the buoyancy-driven flow are the major factors in controlling weld penetration in ferrous alloys, especially austenitic stainless steels such as 304 and 316. Small variations in the concentration of surfactants, such as sulfur and oxygen, in stainless steels cause significant changes in the weld penetration and depth/width (D/W) ratio of the fusion zone. Gas-tungsten arc (GTA) welds were done on low- and high-sulfur 304 and 316 heats using pure argon and argon/oxygen shielding gases. Also, laser beam (LB) welds were done on the 304 and 316 heats using pure argon as the shielding gas. Increase in the sulfur content decreased the D/W ratio for the GTA 304 welds using pure argon, but for the case of LB 304 welds the results were the opposite. For the GTA 316 welds and LB 316 welds, increase in sulfur increased the D/W ratio of the fusion zone. Oxygen increased the D/W ratio of both the 304 and 316 GTA welds.

  13. Effect of plasma welding parameters on the flexural strength of Ti-6Al-4V alloy.

    PubMed

    Lyra e Silva, João Paulo; Fernandes Neto, Alfredo Júlio; Raposo, Luís Henrique Araújo; Novais, Veridiana Resende; de Araujo, Cleudmar Amaral; Cavalcante, Luisa de Andrade Lima; Simamoto Júnior, Paulo Cezar

    2012-01-01

    The aim of this study was to assess the effect of different plasma arc welding parameters on the flexural strength of titanium alloy beams (Ti-6Al-4V). Forty Ti-6Al-4V and 10 NiCr alloy beam specimens (40 mm long and 3.18 mm diameter) were prepared and divided into 5 groups (n=10). The titanium alloy beams for the control group were not sectioned or subjected to welding. Groups PL10, PL12, and PL14 contained titanium beams sectioned and welded at current 3 A for 10, 12 or 14 ms, respectively. Group NCB consisted of NiCr alloy beams welded using conventional torch brazing. After, the beams were subjected to a three-point bending test and the values obtained were analyzed to assess the flexural strength (MPa). Statistical analysis was carried out by one-way ANOVA and Tukey's HSD test at 0.05 confidence level. Significant difference was verified among the evaluated groups (p<0.001), with higher flexural strength for the control group (p<0.05). No significant differences was observed among the plasma welded groups (p>0.05). The NCB group showed the lowest flexural strength, although it was statistically similar to the PL 14 group (p>0.05). The weld depth penetration was not significantly different among the plasma welded groups (p=0.05). Three representative specimens were randomly selected to be evaluated under scanning electron microcopy. The composition of the welded regions was analyzed by energy dispersive X-ray spectroscopy. This study provides an initial set of parameters supporting the use of plasma welding during fabrication of titanium alloy dental frameworks.

  14. Al-to-Cu Friction Stir Lap Welding

    NASA Astrophysics Data System (ADS)

    Firouzdor, Vahid; Kou, Sindo

    2012-01-01

    Recently, friction stir welding (FSW) has been used frequently to join dissimilar metals, for instance, Al to Mg, Cu, and steel. The formation of brittle intermetallic compounds often severely limits the strength and ductility of the resultant welds. In the present study, Al-to-Cu lap FSW was studied by welding 6061 Al to commercially pure Cu. Conventional lap FSW was modified by butt welding a small piece of Al to the top of Cu, with a slight pin penetration into the bottom of Al. At travel speeds up to 127 mm/min (5 ipm), the modified welds were about twice the joint strength and five to nine times the ductility of the conventional lap welds. In the conventional lap welds, voids were present along the Al-Cu interface, and fracture occurred along the interface in tensile testing. No such voids were observed in the modified lap welds, and fracture occurred through Cu. Thus, as in the case of Al-to-Mg lap FSW recently studied by the authors, modified lap FSW significantly improved the weld quality in Al-to-Cu lap FSW. At the relatively high travel speed of 203 mm/min (8 ipm), however, modified lap FSW was no longer superior because of channel formation.

  15. Preparation of titanium diboride powder

    DOEpatents

    Brynestad, Jorulf; Bamberger, Carlos E.

    1985-01-01

    Finely-divided titanium diboride or zirconium diboride powders are formed by reacting gaseous boron trichloride with a material selected from the group consisting of titanium powder, zirconium powder, titanium dichloride powder, titanium trichloride powder, and gaseous titanium trichloride.

  16. Metal Bonded Titanium Diboride

    DTIC Science & Technology

    1952-03-01

    of specimens made from titanium diboride plus 10 percent titanium and 30 percent zirconium . X 100. 22 6. Microstructures of specimens made from...chromium. X 1000 26 10. Microstructures of specimens made from titanium diboride plus 10 percent titanium and 30 percent zirconium . X 1200 27 11. Gain in...shock resistance and oxidation resistance of titanium diboride but zirconium diboride which is isomorphous with titanium diboride has been reported6

  17. NON-MELT PROCESSING OF "LOW-COST", ARMSTRONG TITANIUM AND TITANIUM ALLOY POWDERS

    SciTech Connect

    Peter, William H; Blue, Craig A; Clive, Scorey; Ernst, Bill; McKernan, John; Kiggans, Jim; Rivard, John D; Yu, Dr. Charlie

    2007-01-01

    In the last decade, a considerable effort has been made to develop new methods for producing low cost titanium and titanium powders. The Armstrong process is a new method of producing titanium powder via reducing TiCl4 vapor in molten sodium. The process is scalable, and can be used to produce pre-alloyed powders. Non-melt processing and powder metallurgy approaches are economically viable with the commercially pure powders. In this investigation, several non-melt processing technologies, including vacuum hot pressing, extrusion, roll compaction, and forging techniques, will be evaluated using the Armstrong titanium powders. The metallurgical, chemical, and mechanical properties of the processed titanium samples will be discussed.

  18. Applying NASA's explosive seam welding

    NASA Technical Reports Server (NTRS)

    Bement, Laurence J.

    1991-01-01

    The status of an explosive seam welding process, which was developed and evaluated for a wide range of metal joining opportunities, is summarized. The process employs very small quantities of explosive in a ribbon configuration to accelerate a long-length, narrow area of sheet stock into a high-velocity, angular impact against a second sheet. At impact, the oxide films of both surface are broken up and ejected by the closing angle to allow atoms to bond through the sharing of valence electrons. This cold-working process produces joints having parent metal properties, allowing a variety of joints to be fabricated that achieve full strength of the metals employed. Successful joining was accomplished in all aluminum alloys, a wide variety of iron and steel alloys, copper, brass, titanium, tantalum, zirconium, niobium, telerium, and columbium. Safety issues were addressed and are as manageable as many currently accepted joining processes.

  19. Gentamicin-Eluting Titanium Dioxide Nanotubes Grown on the Ultrafine-Grained Titanium.

    PubMed

    Nemati, Sima Hashemi; Hadjizadeh, Afra

    2017-01-06

    Titanium (Ti)-based materials is the most appropriate choices for the applications as orthopedic and dental implants. In this regard, ultrafine-grained (UFG) titanium with an enhanced mechanical properties and surface energy has attracted more attention. Titanium dioxide (TiO2) nanotubes grown on the titanium could enhance bone bonding, cellular response and are good reservoirs for loading drugs and antibacterial agents. This article investigates gentamicin loading into and release from the TiO2 nanotubes, grown on the UFG compared to coarse-grained (CG) titanium substrate surfaces. Equal Channel Angular Pressing (ECAP) was employed to produce the UFG structure titanium. TiO2 nanotubes were grown by the anodizing technique on both UFG and CG titanium substrate surfaces. Scanning electron microscopy (SEM) imaging confirmed TiO2 nanotube growth on the surface. The UV-vis spectroscopy analysis results show that the amount of gentamicin load-release in the anodized UFG titanium sample is higher than that of CG one which can be explained in terms of thicker TiO2 nanotube arrays layer formed on UFG sample. Moreover, the anodized UFG titanium samples released the drug in a longer time than CG (1 day for the UFG titanium vs. 3 h for the CG one). Regarding wettability analysis, anodized UFG titanium sample showed more enhanced hydrophilicity than CG counterpart. Therefore, the significantly smaller grain size of pure titanium provided by the ECAP technique coupled with appropriate subsequent anodization treatment not only offers a good combination of biocompatibility and adequate mechanical properties but also it provides a delayed release condition for gentamicin.

  20. Welding in airplane construction

    NASA Technical Reports Server (NTRS)

    Rechtlich, A; Schrenk, M

    1928-01-01

    The present article attempts to explain the principles for the production of a perfect weld and to throw light on the unexplained problems. Moreover, it is intended to elucidate the possibilities of testing the strength and reliability of welded parts.

  1. Initial cytotoxicity of novel titanium alloys.

    PubMed

    Koike, M; Lockwood, P E; Wataha, J C; Okabe, T

    2007-11-01

    We assessed the biological response to several novel titanium alloys that have promising physical properties for biomedical applications. Four commercial titanium alloys [Super-TIX(R) 800, Super-TIX(R) 51AF, TIMETAL(R) 21SRx, and Ti-6Al-4V (ASTM grade 5)] and three experimental titanium alloys [Ti-13Cr-3Cu, Ti-1.5Si and Ti-1.5Si-5Cu] were tested. Specimens (n = 6; 5.0 x 5.0 x 3.0 mm(3)) were cast in a centrifugal casting machine using a MgO-based investment and polished to 600 grit, removing 250 mum from each surface. Commercially pure titanium (CP Ti: ASTM grade 2) and Teflon (polytetrafluoroethylene) were used as positive controls. The specimens were cleaned and disinfected, and then each cleaned specimen was placed in direct contact with Balb/c 3T3 fibroblasts for 72 h. The cytotoxicity [succinic dehydrogenase (SDH) activity] of the extracts was assessed using the MTT method. Cytotoxicity of the metals tested was not statistically different compared to the CP Ti and Teflon controls (p > 0.05). These novel titanium alloys pose cytotoxic risks no greater than many other commonly used alloys, including commercially pure titanium. The promising short-term biocompatibility of these Ti alloys is probably due to their excellent corrosion resistance under static conditions, even in biological environments.

  2. Ceramic Weld Backing Evaluation

    DTIC Science & Technology

    1980-06-01

    deposition rate welding processes such as GTAW and GMAW short arc, to some degree, no others will consistently produce full penetration one side welds ...OFFSHORE POWER SYSTEMS 8000 Arlington Expressway Jacksonville, Florida 32211 CERAMIC WELD BACKING EVALUATION FINAL REFORT JUNE 1980 Project Manager...Ceramic Weld Backing Evaluation 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER

  3. Low Gravity Improves Welds

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.; Kaukler, William F.; Plaster, Teresa C.

    1993-01-01

    Hardnesses and tensile strengths greater. Welds made under right conditions in low gravity appear superior to those made under high gravity. Conclusion drawn from results of welding experiments conducted during low- and high-gravity-simulating maneuvers of KC-135 airplane. Results have implications not only for welding in outer space but also for repeated rapid welding on Earth or in airplanes under simulated low gravity to obtain unusually strong joints.

  4. Infrared Thermography For Welding

    NASA Technical Reports Server (NTRS)

    Gilbert, Jeffrey L.; Lucky, Brian D.; Spiegel, Lyle B.; Hudyma, Russell M.

    1992-01-01

    Infrared imaging and image-data-processing system shows temperatures of joint during welding and provides data from which rates of heating and cooling determined. Information used to control welding parameters to ensure reliable joints, in materials which microstructures and associated metallurgical and mechanical properties depend strongly on rates of heating and cooling. Applicable to variety of processes, including tungsten/inert-gas welding; plasma, laser, and resistance welding; cutting; and brazing.

  5. Low Gravity Improves Welds

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.; Kaukler, William F.; Plaster, Teresa C.

    1993-01-01

    Hardnesses and tensile strengths greater. Welds made under right conditions in low gravity appear superior to those made under high gravity. Conclusion drawn from results of welding experiments conducted during low- and high-gravity-simulating maneuvers of KC-135 airplane. Results have implications not only for welding in outer space but also for repeated rapid welding on Earth or in airplanes under simulated low gravity to obtain unusually strong joints.

  6. Effect of friction stir welding and post-weld heat treatment on a nanostructured ferritic alloy

    SciTech Connect

    Mazumder, Baishakhi; Yu, Xinghua; Edmondson, Philip D.; Parish, Chad M.; Miller, Michael K; Meyer, H. M.; Feng, Zhili

    2015-12-08

    Nanostructured ferritic alloys (NFAs) are new generation materials for use in high temperature energy systems, such as nuclear fission or fusion reactors. However, joining these materials is a concern, as their unique microstructure is destroyed by traditional liquid-state welding methods. The microstructural evolution of a friction stir welded 14YWT NFA was investigated by atom probe tomography, before and after a post-weld heat treatment (PWHT) at 1123K. The particle size, number density, elemental composition, and morphology of the titanium-yttrium-oxygenenriched nanoclusters (NCs) in the stir and thermally-affected zones were studied and compared with the base metal. No statistical difference in the size of the NCs was observed in any of these conditions. After the PWHT, increases in the number density and the oxygen enrichment in the NCs were observed. Therefore, these new results provide additional supporting evidence that friction stir welding appears to be a viable joining technique for NFAs, as the microstructural parameters of the NCs are not strongly affected, in contrast to traditional welding techniques.

  7. Effect of friction stir welding and post-weld heat treatment on a nanostructured ferritic alloy

    DOE PAGES

    Mazumder, Baishakhi; Yu, Xinghua; Edmondson, Philip D.; ...

    2015-12-08

    Nanostructured ferritic alloys (NFAs) are new generation materials for use in high temperature energy systems, such as nuclear fission or fusion reactors. However, joining these materials is a concern, as their unique microstructure is destroyed by traditional liquid-state welding methods. The microstructural evolution of a friction stir welded 14YWT NFA was investigated by atom probe tomography, before and after a post-weld heat treatment (PWHT) at 1123K. The particle size, number density, elemental composition, and morphology of the titanium-yttrium-oxygenenriched nanoclusters (NCs) in the stir and thermally-affected zones were studied and compared with the base metal. No statistical difference in the sizemore » of the NCs was observed in any of these conditions. After the PWHT, increases in the number density and the oxygen enrichment in the NCs were observed. Therefore, these new results provide additional supporting evidence that friction stir welding appears to be a viable joining technique for NFAs, as the microstructural parameters of the NCs are not strongly affected, in contrast to traditional welding techniques.« less

  8. Effect of friction stir welding and post-weld heat treatment on a nanostructured ferritic alloy

    NASA Astrophysics Data System (ADS)

    Mazumder, B.; Yu, X.; Edmondson, P. D.; Parish, C. M.; Miller, M. K.; Meyer, H. M.; Feng, Z.

    2016-02-01

    Nanostructured ferritic alloys (NFAs) are new generation materials for use in high temperature energy systems, such as nuclear fission or fusion reactors. However, joining these materials is a concern, as their unique microstructure is destroyed by traditional liquid-state welding methods. The microstructural evolution of a friction stir welded 14YWT NFA was investigated by atom probe tomography, before and after a post-weld heat treatment (PWHT) at 1123K. The particle size, number density, elemental composition, and morphology of the titanium-yttrium-oxygen-enriched nanoclusters (NCs) in the stir and thermally-affected zones were studied and compared with the base metal. No statistical difference in the size of the NCs was observed in any of these conditions. After the PWHT, increases in the number density and the oxygen enrichment in the NCs were observed. Therefore, these new results provide additional supporting evidence that friction stir welding appears to be a viable joining technique for NFAs, as the microstructural parameters of the NCs are not strongly affected, in contrast to traditional welding techniques.

  9. Compaction of Titanium Powders

    SciTech Connect

    Gerdemann, Stephen,J; Jablonski, Paul, J

    2011-05-01

    Accurate modeling of powder densification has been an area of active research for more than 60 years. The earliest efforts were focused on linearization of the data because computers were not readily available to assist with curve-fitting methods. In this work, eight different titanium powders (three different sizes of sponge fines<150 {micro}m,<75 {micro}m, and<45 {micro}m; two different sizes of a hydride-dehydride [HDH]<75 {micro}m and<45 {micro}m; an atomized powder; a commercially pure [CP] Ti powder from International Titanium Powder [ITP]; and a Ti 6 4 alloy powder) were cold pressed in a single-acting die instrumented to collect stress and deformation data during compaction. From these data, the density of each compact was calculated and then plotted as a function of pressure. The results show that densification of all the powders, regardless of particle size, shape, or chemistry, can be modeled accurately as the sum of an initial density plus the sum of a rearrangement term and a work-hardening term. These last two terms are found to be a function of applied pressure and take the form of an exponential rise.

  10. Compaction of Titanium Powders

    SciTech Connect

    Stephen J. Gerdemann; Paul D. Jablonski

    2010-11-01

    Accurate modeling of powder densification has been an area of active research for more than 60 years. The earliest efforts were focused on linearization of the data because computers were not readily available to assist with curve-fitting methods. In this work, eight different titanium powders (three different sizes of sponge fines <150 μm, <75 μm, and < 45 μm; two different sizes of a hydride-dehydride [HDH] <75 μm and < 45 μm; an atomized powder; a commercially pure [CP] Ti powder from International Titanium Powder [ITP]; and a Ti 6 4 alloy powder) were cold pressed in a single-acting die instrumented to collect stress and deformation data during compaction. From these data, the density of each compact was calculated and then plotted as a function of pressure. The results show that densification of all the powders, regardless of particle size, shape, or chemistry, can be modeled accurately as the sum of an initial density plus the sum of a rearrangement term and a work-hardening term. These last two terms are found to be a function of applied pressure and take the form of an exponential rise.

  11. Comparing Laser Welding Technologies with Friction Stir Welding for Production of Aluminum Tailor-Welded Blanks

    SciTech Connect

    Hovanski, Yuri; Carsley, John; Carlson, Blair; Hartfield-Wunsch, Susan; Pilli, Siva Prasad

    2014-01-15

    A comparison of welding techniques was performed to determine the most effective method for producing aluminum tailor-welded blanks for high volume automotive applications. Aluminum sheet was joined with an emphasis on post weld formability, surface quality and weld speed. Comparative results from several laser based welding techniques along with friction stir welding are presented. The results of this study demonstrate a quantitative comparison of weld methodologies in preparing tailor-welded aluminum stampings for high volume production in the automotive industry. Evaluation of nearly a dozen welding variations ultimately led to down selecting a single process based on post-weld quality and performance.

  12. Laser welding and syncristallization techniques comparison: “Ex vivo” study

    PubMed Central

    Meleti, Marco; Vescovi, Paolo; Merigo, Elisabetta; Rocca, Jean-Paul

    2013-01-01

    Background and aims: Stabilization of implant abutments through electric impulses at high voltage for a very short time (electrowelding) was developed in the Eighties. In 2009, the same procedure was performed through the use of laser (laser welding) The aim of this study is to compare electrowelding and laser welding for intra-oral implant abutments stabilization on “ex vivo models” (pig jaws). Materials and methods: Six bars were welded with two different devices (Nd:YAG laser and Electrowelder) to eighteen titanium implant abutment inserted in three pig jaws. During the welding process, thermal increase was recorded, through the use of k-thermocouples, in the bone close to the implants. The strength of the welded joints was evaluated by a traction test after the removal of the implants. For temperature measurements a descriptive analysis and for traction test “values unpaired t test with Welch's correction” were performed: the significance level was set at P<0.05. Results: Laser welding gives a lower thermal increase than Electrowelding at the bone close to implants (Mean: 1.97 and 5.27); the strength of laser welded joints was higher than that of Electrowelding even if nor statistically significant. (Mean: 184.75 and 168.29) Conclusion: Electrowelding seems to have no advantages, in term of thermal elevation and strength, while laser welding may be employed to connect titanium implants for immediate load without risks of thermal damage at surrounding tissues. PMID:24511205

  13. Coil Welding Aid

    NASA Technical Reports Server (NTRS)

    Wiesenbach, W. T.; Clark, M. C.

    1983-01-01

    Positioner holds coil inside cylinder during tack welding. Welding aid spaces turns of coil inside cylinder and applies contact pressure while coil is tack-welded to cylinder. Device facilitates fabrication of heat exchangers and other structures by eliminating hand-positioning and clamping of individual coil turns.

  14. Variable polarity arc welding

    NASA Technical Reports Server (NTRS)

    Bayless, E. O., Jr.

    1991-01-01

    Technological advances generate within themselves dissatisfactions that lead to further advances in a process. A series of advances in welding technology which culminated in the Variable Polarity Plasma Arc (VPPA) Welding Process and an advance instituted to overcome the latest dissatisfactions with the process: automated VPPA welding are described briefly.

  15. Welding Course Curriculum.

    ERIC Educational Resources Information Center

    Genits, Joseph C.

    This guide is intended for use in helping students gain a fundamental background on the major aspects of the welding trade. The course emphasis is on mastery of the manipulative skills necessary to develop successful welding techniques and on acquisition of an understanding of the specialized tools and equipment used in welding. The first part…

  16. Instructional Guidelines. Welding.

    ERIC Educational Resources Information Center

    Fordyce, H. L.; Doshier, Dale

    Using the standards of the American Welding Society and the American Society of Mechanical Engineers, this welding instructional guidelines manual presents a course of study in accordance with the current practices in industry. Intended for use in welding programs now practiced within the Federal Prison System, the phases of the program are…

  17. Welding Plutonium Storage Containers

    SciTech Connect

    HUDLOW, SL

    2004-04-20

    The outer can welder (OCW) in the FB-Line Facility at the Savannah River Site (SRS) is a Gas Tungsten Arc Weld (GTAW) system used to create outer canisters compliant with the Department of Energy 3013 Standard, DOE-STD-3013-2000, Stabilization, Packaging, and Storage of Plutonium-Bearing Materials. The key welding parameters controlled and monitored on the outer can welder Data Acquisition System (DAS) are weld amperage, weld voltage, and weld rotational speed. Inner 3013 canisters from the Bagless Transfer System that contain plutonium metal or plutonium oxide are placed inside an outer 3013 canister. The canister is back-filled with helium and welded using the outer can welder. The completed weld is screened to determine if it is satisfactory by reviewing the OCW DAS key welding parameters, performing a helium leak check, performing a visual examination by a qualified weld inspector, and performing digital radiography of the completed weld. Canisters with unsatisfactory welds are cut open and repackaged. Canisters with satisfactory welds are deemed compliant with the 3013 standard for long-term storage.

  18. Portable Weld Tester.

    ERIC Educational Resources Information Center

    Eckert, Douglas

    This training manual, which was developed for employees of an automotive plant, is designed to teach trainees to operate a portable weld tester (Miyachi MM-315). In chapter 1, the weld tester's components are illustrated and described, and the procedure for charging its batteries is explained. Chapter 2 illustrates the weld tester's parts,…

  19. Active weld control

    NASA Technical Reports Server (NTRS)

    Powell, Bradley W.; Burroughs, Ivan A.

    1994-01-01

    Through the two phases of this contract, sensors for welding applications and parameter extraction algorithms have been developed. These sensors form the foundation of a weld control system which can provide action weld control through the monitoring of the weld pool and keyhole in a VPPA welding process. Systems of this type offer the potential of quality enhancement and cost reduction (minimization of rework on faulty welds) for high-integrity welding applications. Sensors for preweld and postweld inspection, weld pool monitoring, keyhole/weld wire entry monitoring, and seam tracking were developed. Algorithms for signal extraction were also developed and analyzed to determine their application to an adaptive weld control system. The following sections discuss findings for each of the three sensors developed under this contract: (1) weld profiling sensor; (2) weld pool sensor; and (3) stereo seam tracker/keyhole imaging sensor. Hardened versions of these sensors were designed and built under this contract. A control system, described later, was developed on a multiprocessing/multitasking operating system for maximum power and flexibility. Documentation for sensor mechanical and electrical design is also included as appendices in this report.

  20. Portable Weld Tester.

    ERIC Educational Resources Information Center

    Eckert, Douglas

    This training manual, which was developed for employees of an automotive plant, is designed to teach trainees to operate a portable weld tester (Miyachi MM-315). In chapter 1, the weld tester's components are illustrated and described, and the procedure for charging its batteries is explained. Chapter 2 illustrates the weld tester's parts,…

  1. Welding Course Curriculum.

    ERIC Educational Resources Information Center

    Genits, Joseph C.

    This guide is intended for use in helping students gain a fundamental background on the major aspects of the welding trade. The course emphasis is on mastery of the manipulative skills necessary to develop successful welding techniques and on acquisition of an understanding of the specialized tools and equipment used in welding. The first part…

  2. Penetration in GTA welding

    SciTech Connect

    Heiple, C.R.; Burgardt, P.

    1990-01-01

    The size and shape of the weld bead produced in GTA welding depends on the magnitude and distribution of the energy incident on the workpiece surfaces as well as the dissipation of that energy in the workpiece. The input energy is largely controllable through the welding parameters selected, however the dissipation of that energy in the workpiece is less subject to control. Changes in energy dissipation can produce large changes in weld shape or penetration. Heat transport away from the weld pool is almost entirely by conduction, but heat transport in the weld pool is more complicated. Heat conduction through the liquid is an important component, but heat transport by convection (mass transport) is often the dominant mechanism. Convective heat transport is directional and changes the weld pool shape from that produced by conduction alone. Surface tension gradients are often the dominant forces driving fluid flow in GTA weld pools. These gradients are sensitive functions of weld pool chemistry and the energy input distribution to the weld. Experimental and theoretical work conducted primarily in the past decade has greatly enhanced our understanding of weld pool fluid flow, the forces which drive it, and its effects on weld pool shape. This work is reviewed here. While less common, changes in energy dissipation through the unmelted portion of the workpiece can also affect fusion zone shape or penetration. These effects are also described. 41 refs., 9 figs.

  3. Coil Welding Aid

    NASA Technical Reports Server (NTRS)

    Wiesenbach, W. T.; Clark, M. C.

    1983-01-01

    Positioner holds coil inside cylinder during tack welding. Welding aid spaces turns of coil inside cylinder and applies contact pressure while coil is tack-welded to cylinder. Device facilitates fabrication of heat exchangers and other structures by eliminating hand-positioning and clamping of individual coil turns.

  4. Laser welding method for removal of instruments debris from root canals.

    PubMed

    Hagiwara, Ryoichi; Suehara, Masataka; Fujii, Rie; Kato, Hiroshi; Nakagawa, Kan-ichi; Oda, Yutaka

    2013-01-01

    The purpose of this study was to clarify the viability of a novel method for removing debris from broken instruments from root canals using a laser apparatus. Laser welding was performed on stainless steel or nickel titanium files using an Nd:YAG laser. Retention force between the files and extractors was measured. Increase in temperature on the root surface during laser irradiation was recorded and the irradiated areas evaluated with a scanning electron microscope. Retention force on stainless steel was significantly greater than that on nickel titanium. The maximum temperature increase was 4.1°C. The temperature increase on the root surface was greater in the vicinity of the welded area than that at the apical area. Scanning electron microscopy revealed that the files and extractors were welded together. These results indicate that the laser welding method is effective in removing debris from broken instruments from root canals.

  5. A comparison of tensile weld strength and microstructural changes in four arch wires, before and after immersion in 1.23% acidulated phosphate fluoride solution: an in-vitro study.

    PubMed

    Tela, Shantanu; Bhosale, Veera; Sable, Ravindranath; Abdullah, Roopa; Halli, Rajshekhar

    2013-01-01

    The objective of this study is to evaluate and to compare the tensile weld strengths and microstructural changes in four archwires namely beta titanium, stainless steel (SS), blue elgiloy and timolium before and after immersion in 1.23% acidulated phosphate fluoride (APF) solution. The mean tensile weld strength of a weld joint of four arch wires were compared pre-fluoride (Group 1) with post fluoride (Group 2) and the microstructural characteristics of weld joints were evaluated under an optical microscope. The mean tensile weld strength for beta titanium was 445.64 N/mm 2, blue elgiloy was 363.26 N/mm 2, SS was 358.30 N/mm 2 and timolium was 308.62 N/mm 2. After immersion in fluoride the mean tensile strength for beta titanium was 427.16 N/mm 2, blue elgiloy was 359.86 N/mm 2, SS is 349.44 N/mm 2 and timolium is 294.86 N/mm 2. After immersion in fluoride, the beta titanium and SS had a smooth fusion at the center of weld assembly with characteristic nugget formation. The beta titanium weld assembly had greater tensile weld strength than other welded assemblies. Blue elgiloy ranked second, whereas SS and timolium were third and fourth respectively. The wires in descending order of their mean tensile weld strength, on evaluation of their weld joints were found to be: Beta titanium > blue elgiloy > SS > timolium. The reduction in tensile weld strength was statistically insignificant for all the archwires after exposure to 1.23% APF at 37°C for 90 min.

  6. Advanced Techniques for In-Situ Monitoring of Phase Transformations During Welding Using Synchrotron-Based X-Ray Diffraction

    SciTech Connect

    Elmer, J W; Palmer, T A; Zhang, W; DebRoy, T

    2005-06-05

    Understanding the evolution of microstructure in welds is an important goal of welding research because of the strong correlation between weld microstructure and weld properties. To achieve this goal it is important to develop a quantitative measure of phase transformations encountered during welding in order to ultimately develop methods for predicting weld microstructures from the characteristics of the welding process. To aid in this effort, synchrotron radiation methods have been developed at Lawrence Livermore National Laboratory (LLNL) for direct observation of microstructure evolution during welding. Using intense, highly collimated synchrotron radiation, the atomic structure of the weld heat affected and fusion zones can be probed in real time. Two synchrotron-based techniques, known as spatially resolved (SRXRD) and time resolved (TRXRD) x-ray diffraction, have been developed for these investigations. These techniques have now been used to investigate welding induced phase transformations in titanium alloys, low alloy steels, and stainless steel alloys. This paper will provide a brief overview of these methods and will discuss microstructural evolution during the welding of low carbon (AISI 1005) and medium carbon (AISI 1045) steels where the different levels of carbon influence the evolution of microstructures during welding.

  7. Forge Welding of Magnesium Alloy to Aluminum Alloy Using a Cu, Ni, or Ti Interlayer

    NASA Astrophysics Data System (ADS)

    Yamagishi, Hideki; Sumioka, Junji; Kakiuchi, Shigeki; Tomida, Shogo; Takeda, Kouichi; Shimazaki, Kouichi

    2015-08-01

    The forge-welding process was examined to develop a high-strength bonding application of magnesium (Mg) alloy to aluminum (Al) alloy under high-productivity conditions. The effect of the insert material on the tensile strength of the joints, under various preheat temperatures and pressures, was investigated by analyzing the reaction layers of the bonded interface. The tensile strengths resulting from direct bonding, using pure copper (Cu), pure nickel (Ni), and pure titanium (Ti) inserts were 56, 100, 119, and 151 MPa, respectively. The maximum joint strength reached 93 pct with respect to the Mg cast billet. During high-pressure bonding, a microscopic plastic flow occurred that contributed to an anchor effect and the generation of a newly formed surface at the interface, particularly prominent with the Ti insert in the form of an oxide layer. The bonded interfaces of the maximum-strength inserts were investigated using scanning electron microscopy-energy-dispersive spectroscopy and electron probe microanalysis. The diffusion reaction layer at the bonded interface consisted of brittle Al-Mg intermetallics having a thickness of approximately 30 μm. In contrast, for the three inserts, the thicknesses of the diffusion reaction layer were infinitely thin. For the pure Ti insert, exhibiting the maximum tensile strength value among the inserts tested, focused ion beam-transmission electron microscopy-EDS analysis revealed a 60-nm-thick Al-Ti reaction layer, which had formed at the bonded interface on the Mg alloy side. Thus, a high-strength Al-Mg bonding method in air was demonstrated, suitable for mass production.

  8. Microstructure characterization of laser welded Ti-6Al-4V fusion zones

    SciTech Connect

    Xu, Pei-quan; Li, Leijun Zhang, Chunbo

    2014-01-15

    The as-welded microstructure of laser-welded Ti-6Al-4V is characterized as a function of CO2 key-hole mode laser welding speed. Martensitic α′ is the predominant phase, with some α and retained β. Phase transformation is affected by the cooling rate through laser welding speed. A higher welding speed of 1.6 to 2.0 m/min produced more martensite α′ and less retained β in the welds. 1.4 m/min welding speed produced small amounts of α, besides the martensite α′. A trace of δ titanium hydride phase seems to have formed in the weld fusion zone. Moiré fringes are a common feature in the TEM microstructure, due to abundance of multi-phase interfaces. Tensile twins and clusters of dislocations indicate that plastic deformation has happened in the as-welded microstructure, indicating the local stress levels to be approaching the yield stress on-cooling during laser welding.

  9. Advances in Joining Techniques Used in Development of SPF/DB Titanium Sandwich Reinforced with Metal Matrices

    NASA Technical Reports Server (NTRS)

    Fischler, J. E.

    1985-01-01

    Three and four-sheet expanded titanium sandwich sheets have been developed at Douglas Aircraft Company, a division of McDonnell Douglas Corporation, under contract to NASA Langley Research Center. In these contracts, spot welding and roll seam welding are used to join the core sheets. These core sheets are expanded to the face sheets and diffusion bonded to form various type cells. The advantages of various cell shapes and the design parameters for optimizing the wing and fuselage concepts are discussed versus the complexity of the spot weld pattern. In addition, metal matrix composites of fibers in an aluminum matrix encapsulated in a titanium sheath are aluminum brazed successfully to the titanium sandwich face sheets. The strength and crack growth rate of the superplastic-formed/diffusion bonded (SPF/DB) titanium sandwich with and without the metal matrix composites are described.

  10. T-joints of Ti alloys with hybrid laser-MIG welding: macro-graphic and micro-hardness analyses

    NASA Astrophysics Data System (ADS)

    Spina, R.; Sorgente, D.; Palumbo, G.; Scintilla, L. D.; Brandizzi, M.; Satriano, A. A.; Tricarico, L.

    2012-03-01

    Titanium alloys are characterized by high mechanical properties and elevated corrosion resistance. The combination of laser welding with MIG/GMAW has proven to improve beneficial effects of both processes (keyhole, gap-bridging ability) while limiting their drawbacks (high thermal gradient, low mechanical resistance) In this paper, the hybrid Laser-GMAW welding of Ti-6Al-4V 3-mm thick sheets is investigated using a specific designed trailing shield. The joint geometry was the double fillet welded T-joint. Bead morphologies, microstructures and mechanical properties (micro-hardness) of welds were evaluated and compared to those achieved for the base metals.

  11. Investigation of the Pyrometallurgical, Physical and Mechanical Behavior of Weld Metal

    DTIC Science & Technology

    1989-06-01

    has been used to make homogeneous high purity ceramic chemicals. The sol gel process has also been demonstrated to achieve properties of the welding...extremely cost effective in reducing cold cracking associated with high strenght steel weldments (see publication #12). 2.4 Aluminum Weld Metal Cracking...Al-Li-Cu alloys without sufficient grain refiners have a high susceptibility of hot tearing and inferior weldability. Additions of titanium and

  12. Method for welding beryllium

    DOEpatents

    Dixon, Raymond D.; Smith, Frank M.; O'Leary, Richard F.

    1997-01-01

    A method is provided for joining beryllium pieces which comprises: depositing aluminum alloy on at least one beryllium surface; contacting that beryllium surface with at least one other beryllium surface; and welding the aluminum alloy coated beryllium surfaces together. The aluminum alloy may be deposited on the beryllium using gas metal arc welding. The aluminum alloy coated beryllium surfaces may be subjected to elevated temperatures and pressures to reduce porosity before welding the pieces together. The aluminum alloy coated beryllium surfaces may be machined into a desired welding joint configuration before welding. The beryllium may be an alloy of beryllium or a beryllium compound. The aluminum alloy may comprise aluminum and silicon.

  13. Flow visualization of Marangoni convection in simulated weld pools

    NASA Astrophysics Data System (ADS)

    Limmaneevichitr, Chaowalit

    Many computational models and experiments have demonstrated that Marangoni convection dominates other forces in weld pools under the practical gas tungsten arc welding conditions. The Marangoni convection in the weld pools is important because it has a decisive effect on the reproducibility of weld geometry and is responsible for other welding problems, including arc wander, humped beads, and porosity. A flow visualization technique was developed to observe the Marangoni convection in simulated weld pool of sodium nitrate (NaNO3) subject to a defocused CO2 laser beam. The intent was to provide a better understanding of Marangoni convection in weld pools, which is impossible to conduct in opaque metal pools, and to understand the effect of the power and diameter of the heat source on the Marangoni convection. The study of the effect of the Marangoni convection on the weld pool shape was conducted in stationary welds of NaNO3 and gallium (Ga), a high and low Prandtl number material, respectively. It is proposed that, in the absence of a surface-active agent and a significant electromagnetic force, pool bottom convexity increases with increasing value of Peclet number. It was shown that for a given material composition and welding process, the weld shape often reveals a good deal about the nature of weld pool convection. Finally, a transparent pool of NaNO3 with potassium propionate (C2H5COOK) as a surface-active agent was used for the flow visualization. The reversed Marangoni convection was clearly observed. The stationary laser weldings showed deeper weld pools in NaNO3 containing 1 mole % C2H5COOK than in pure NaNO 3. This is consistent with the effect Of C2H5COOK on the convection pattern observed in flow visualization. It is believed that the results of this dissertation are the valuable tools to explain the significance of the Marangoni convection in weld pools and to explain why small differences in some specific chemical composition have such a profound

  14. Metallographic Preparation of Space Shuttle Reaction Control System Thruster Electron Beam Welds for Electron Backscatter Diffraction

    NASA Technical Reports Server (NTRS)

    Martinez, James

    2011-01-01

    A Space Shuttle Reaction Control System (RCS) thruster failed during a firing test at the NASA White Sands Test Facility (WSTF), Las Cruces, New Mexico. The firing test was being conducted to investigate a previous electrical malfunction. A number of cracks were found associated with the fuel closure plate/injector assembly (Fig 1). The firing test failure generated a flight constraint to the launch of STS-133. A team comprised of several NASA centers and other research institutes was assembled to investigate and determine the root cause of the failure. The JSC Materials Evaluation Laboratory was asked to compare and characterize the outboard circumferential electron beam (EB) weld between the fuel closure plate (Titanium 6Al-4V) and the injector (Niobium C-103 alloy) of four different RCS thrusters, including the failed RCS thruster. Several metallographic challenges in grinding/polishing, and particularly in etching were encountered because of the differences in hardness, ductility, and chemical resistance between the two alloys and the bimetallic weld. Segments from each thruster were sectioned from the outboard weld. The segments were hot-compression mounted using a conductive, carbon-filled epoxy. A grinding/polishing procedure for titanium alloys was used [1]. This procedure worked well on the titanium; but a thin, disturbed layer was visible on the niobium surface by means of polarized light. Once polished, each sample was micrographed using bright field, differential interference contrast optical microscopy, and scanning electron microscopy (SEM) using a backscatter electron (BSE) detector. No typical weld anomalies were observed in any of the cross sections. However, areas of large atomic contrast were clearly visible in the weld nugget, particularly along fusion line interfaces between the titanium and the niobium. This prompted the need to better understand the chemistry and microstructure of the weld (Fig 2). Energy Dispersive X-Ray Spectroscopy (EDS

  15. (Welding under extreme conditions)

    SciTech Connect

    Davis, S.A.

    1989-09-29

    The traveler was an invited member of the United States delegation and representative of the Basic Energy Science Welding Science program at the 42nd Annual International Institute of Welding (IIW) Assembly and Conference held in Helsinki, Finland. The conference and the assembly was attended by about 600 delegates representing 40 countries. The theme of the conference was welding under extreme conditions. The conference program contained several topics related to welding in nuclear, arctic petrochemical, underwater, hyperbaric and space environments. At the annual assembly the traveler was a delegate (US) to two working groups of the IIW, namely Commission IX and welding research study group 212. Following the conference the traveler visited the Danish Welding Institute in Copenhagen and the Risoe National Laboratory in Roskilde. Prior to the conference the traveler visited Lappeenranta University of Technology and presented an invited seminar entitled Recent Advances in Welding Science and Technology.''

  16. Optically controlled welding system

    NASA Technical Reports Server (NTRS)

    Gordon, Stephen S. (Inventor)

    1988-01-01

    An optically controlled welding system wherein a welding torch having through-the-torch viewing capabilities is provided with an optical beam splitter to create a transmitted view and a reflective view of a welding operation. These views are converted to digital signals which are then processed and utilized by a computerized robotic welder to make the welding torch responsive thereto. Other features include an actively cooled electrode holder which minimizes a blocked portion of the view by virtue of being constructed of a single spoke or arm, and a weld pool contour detector comprising a laser beam directed onto the weld pool with the position of specular radiation reflected therefrom, being characteristic of a penetrated or unpenetrated condition of the weld pool.

  17. Optically controlled welding system

    NASA Technical Reports Server (NTRS)

    Gordon, Stephen S. (Inventor)

    1989-01-01

    An optically controlled welding system (10) wherein a welding torch (12) having through-the-torch viewing capabilities is provided with an optical beam splitter (56) to create a transmitted view and a reflective view of a welding operation. These views are converted to digital signals which are then processed and utilized by a computerized robotic welder (15) to make the welding torch responsive thereto. Other features includes an actively cooled electrode holder (26) which minimizes a blocked portion of the view by virtue of being constructed of a single spoke or arm (28) and a weld pool contour detector (14) comprising a laser beam directed onto the weld pool with the position of specular radiation reflected therefrom being characteristic of a penetrated or unpenetrated condition of the weld pool.

  18. Robotic Welding Of Injector Manifold

    NASA Technical Reports Server (NTRS)

    Gilbert, Jeffrey L.; Shelley, D. Mark

    1992-01-01

    Brief report presents history, up through October 1990, of continuing efforts to convert from manual to robotic gas/tungsten arc welding in fabrication of main injector inlet manifold of main engine of Space Shuttle. Includes photographs of welding machinery, welds, and weld preparations. Of interest to engineers considering establishment of robotic-welding facilities.

  19. Robotic Welding Of Injector Manifold

    NASA Technical Reports Server (NTRS)

    Gilbert, Jeffrey L.; Shelley, D. Mark

    1992-01-01

    Brief report presents history, up through October 1990, of continuing efforts to convert from manual to robotic gas/tungsten arc welding in fabrication of main injector inlet manifold of main engine of Space Shuttle. Includes photographs of welding machinery, welds, and weld preparations. Of interest to engineers considering establishment of robotic-welding facilities.

  20. The morphological evolution of the axial structure and the curved columnar grain in the weld

    NASA Astrophysics Data System (ADS)

    Han, Rihong; Lu, Shanping; Dong, Wenchao; Li, Dianzhong; Li, Yiyi

    2015-12-01

    The competitive growth of microstructures in the entire weld pool for both the Al-Cu alloy and the pure aluminum was simulated by the cellular automata method to comparatively investigate the micro-mechanisms for the morphological evolution of the axial structure and the curved columnar grain in the weld. The competitive mechanism of grains during the epitaxial growth and the morphological evolution of the grain structure in the weld with various welding speeds were studied. The results indicate that both the thermal conditions and the solidification characteristic of the weld metal exert an important influence on the grain competition and the resulting structure in the weld. For the Al-Cu alloy, the dendritic structure with a large S/L interface curvature appears during the epitaxial growth. The preferential orientation affects the competition result obviously. Owing to the anisotropic growth kinetics, the straight axial structure forms at low welding speeds. With the increase of the welding speed, the width of the axial region decreases and eventually disappears. For the pure aluminum, the S/L interface during the epitaxial growth is planar, and the grain competition is controlled by the thermal conditions completely. The columnar grains curve gradually to follow the highest temperature gradient direction at low welding speeds and become straight at high welding speeds.