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Sample records for pure titanium welds

  1. 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. PMID:24474361

  2. 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.

  3. The Fatigue Behavior of Built-Up Welded Beams of Commercially Pure Titanium

    NASA Astrophysics Data System (ADS)

    Patnaik, Anil; Poondla, Narendra; Bathini, Udaykar; Srivatsan, T. S.

    2011-10-01

    In this article, the results of a recent study aimed at evaluating, understanding, and rationalizing the extrinsic influence of fatigue loading on the response characteristics of built-up welded beams made from commercially pure titanium (Grade 2) are presented and discussed. The beams were made from welding plates and sheets of titanium using the pulsed gas metal arc welding technique to form a structural beam having an I-shaped cross section. The welds made for the test beams of the chosen metal were fillet welds using a matching titanium filler metal wire. The maximum and minimum load values at which the built-up beams were cyclically deformed were chosen to be within the range of 22-45% of the maximum predicted flexural static load. The beams were deformed in fatigue at a stress ratio of 0.1 and constant frequency of 5 Hz. The influence of the ratio of maximum load with respect to the ultimate failure load on fatigue performance, quantified in terms of fatigue life, was examined. The percentage of maximum load to ultimate load that resulted in run-out of one million cycles was established. The overall fracture behavior of the failed beam sample was characterized by scanning electron microscopy observations to establish the conjoint influence of load severity, intrinsic microstructural effects, and intrinsic fracture surface features in governing failure by fracture.

  4. 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. PMID:19496406

  5. Investigations on the Effects of the Tool Material, Geometry, and Tilt Angle on Friction Stir Welding of Pure Titanium

    NASA Astrophysics Data System (ADS)

    Reshad Seighalani, K.; Besharati Givi, M. K.; Nasiri, A. M.; Bahemmat, P.

    2010-10-01

    Friction stir welding (FSW) parameters, such as tool material, tool geometry, tilt angle, tool rotational speed, welding speed, and axial force play a major role in the weld quality of titanium alloys. Because of excessive erosion, tool material and geometry play the main roles in FSW of titanium alloys. Therefore, in the present work for the first time, tool material and geometry, tool tilt angle, cooling system and shielding gas effects on macrostructure, microstructure, and mechanical properties of pure titanium weld joint were investigated. Result of this research shows that Ti can be joined by the FSW, using a tool with a shoulder made of tungsten (W) and simple pin made of tungsten carbide (WC). The best conditions for welding were use of compressed air as a cooling system, tool tilt angle of 1°, and a stream of Argon as a shielding medium. Investigation on mechanical properties shows that the tensile strength and the yield strength of the welded joint in the best case could be similar to the corresponding strengths of the base metal.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Studies on laser- and plasma-welded titanium.

    PubMed

    Roggensack, M; Walter, M H; Böning, K W

    1993-03-01

    In recent years, titanium has become a material of major interest in prosthetic dentistry. Due to its chemical properties, titanium has to be processed differently from conventional alloys. In this paper, two different methods of welding were investigated. Specimens machined from pure titanium rods were fused either by laser welding or plasma welding. Hardness profiles and light microscopy images were taken in the region of the weld. The mechanical properties were tested by alternating bending fatigue tests up to 3 million cycles. Light microscopy images and hardness profiles showed a larger heat-affected zone after plasma welding compared to laser welding. No significant differences comparing fatigue strength could be found between the two methods of welding. However, extreme loads led to earlier fatigue in the plasma-welded specimens. SEM images of the laser-welded joints showed fractures in the welding zone, while the plasma-welded specimens fractured mostly beyond the heat-affected zone. From these results, it can be assumed that both methods are suitable for welding titanium. At the moment, laser welding is the more suitable technique in dentistry because of its lower thermal alteration of the workpieces. PMID:8595837

  11. 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.

  12. [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. PMID:12553259

  13. 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. PMID:18546764

  14. Spatially resolved X-ray diffraction phase mapping and {alpha} {r_arrow} {beta} {r_arrow} {alpha} transformation kinetics in the heat-affected zone of commercially pure titanium arc welds

    SciTech Connect

    Elmer, J.W.; Wong, J.; Ressler, T.

    1998-11-01

    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 using a 180-{micro}m-diameter X-ray beam at the Stanford Synchrotron Radiation Laboratory (SSRL) (Stanford, CA) to probe the phases present in the HAZ of a 1.9 kW weld moving at 1.1 mm/s. Results of sequential linear X-ray diffraction scans made perpendicular to the weld direction were combined to construct a phase transformation map around the liquid weld pool. This map identifies six HAZ microstructural regions between the liquid weld pool and the base metal: (1) {alpha}-Ti that is undergoing annealing and recrystallization; (2) completely recrystallized {alpha}-Ti; (3) partially transformed {alpha}-Ti, where {alpha}-Ti and {beta}-Ti coexist; (4) single-phase {beta}-Ti; (5) back-transformed {alpha}Ti; and (6) recrystallized {alpha}-Ti plus back-transformed {alpha}-Ti. Although the microstructure consisted predominantly of {alpha}-Ti, both prior to and after the weld, the crystallographically textured starting material was altered during welding to produce different {alpha}-Ti textures within the resulting HAZ. Based on the travel speed of the weld, the {alpha} {r_arrow} {beta} transformation was measured to take 1.83 seconds during heat, while the {beta} {r_arrow} {alpha} transformation was measured to take 0.91 seconds during cooling. The {alpha} {r_arrow} {beta} transformation was characterized to be dominated by long-range diffusion growth on the leading (heating) side of the weld, while the {beta} {r_arrow} {alpha} transformation was characterized to be predominantly massive on the trailing (cooling) side of the weld, with a massive growth rate on the order of 100 {micro}m/s.

  15. 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.

  16. 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.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

  19. 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.

  20. Electroslag welding of titanium and its alloys

    SciTech Connect

    Malin, V.Y.

    1985-02-01

    The objective of this review is to examine the specific requirements of the electroslag welding process when applied to thick-wall components made from titanium or its various alloys. The review includes process variations, flux and equipment development requirements, specifics of the various techniques, wire and shielding gas supply problems, welding conditions, properties of the welds, quality control, and other topics.

  1. 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.

  2. 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.

  3. 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.

  4. [Study of pure titanium electrolytic polishing].

    PubMed

    Morita, N

    1990-03-01

    This study attempted to polish pure titanium test pieces electrolytically to mirror surface at the size of cast denture frames. Electrolytic polishing of pure titanium could be done on an area of 30 cm2 with a non-aqueous electrolyte. Small pure titanium plates could be polished electrolytically, but a uniformly smooth surface could not be obtained easily with large testpiece. The optimal electrolytic conditions were 30 V for 6 min at 25 degrees C using a solution consisting of 70 ml ethyl alcohol, 30 ml iso-propyl alcohol, 6 g aluminum chloride, and 25 g zinc chloride. The solution was safe and had less restriction of frequency of use. PMID:2135513

  5. 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.

  6. 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.

  7. 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. PMID:23636297

  8. 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

  9. 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.

  10. Cryogenic acoustic loss of pure and alloyed titanium

    NASA Astrophysics Data System (ADS)

    Matacz, A. L.; Veitch, P. J.; Blair, D. G.

    Low acoustic loss, high yield strength cryogenic materials are required for various high precision experiments, resonant-bar gravitational radiation antennae in particular. We report here acoustic loss measurements of commerically pure and alloyed titanium samples between 4.2 and 300 K. It is shown that machining damage of the surface significantly increased the acoustic loss of pure titanium, particularly below 100 K, and that the high strength alloy Ti-6AI-4V had significantly greater acoustic loss than pure titanium.

  11. Multilayered titanium-steel composite produced by explosive welding

    NASA Astrophysics Data System (ADS)

    Malyutina, Yu. N.; Skorohod, K. A.; Shevtsova, K. E.; Chesnokova, A. V.

    2015-10-01

    Multilayered titanium-steel composite consisting of alternating high-strength and ductile metallic materials were produced by explosive welding. Different types of weld joints formed in the composite were recognized by methods of microstructural analysis. Wave-shaped and flat geometry of welds are typical of steel and titanium layers, respectively. Structural features such as lack of penetration, shear bands, recrystallized metals and martensitic structure were detected in the vortex and weld-adjacent zones of impacted materials. The impact strength of the layered composite was 65% higher as compared to that of VT23 titanium alloy. A favorable role of interlayers in the multilayered composite has been confirmed by toughness tests.

  12. 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.

  13. 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. PMID:26045042

  14. Dissimilar friction welding of titanium alloys to alloy 718

    SciTech Connect

    Kuo, M.; Albright, C.E.; Baeslack, W.A. III

    1994-12-31

    The design of advanced, high-performance gas-turbine engines will require the utilization of elevated-temperature titanium-based materials, including conventional alloys, titanium aluminides, and titanium metal-matrix composites. The most efficient utilization of these materials in the engine compressor section would be achieved by directly joining these materials to existing nickel-base superalloys, such as Alloy 718. To date, the dissimilar welding of titanium alloys to nickel-based alloys has not been common practice because intermetallic compounds form in the weld and cause embrittlement. Special welding techniques must be developed to inhibit this compound formation and to provide high strength welds. In this investigation, a friction welding process was developed for joining titanium alloys (Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V) to nickel-based superalloy Alloy 718. An interlayer system comprised of copper and niobium sheet layers was employed as a diffusion barrier and weld deformation enhancer. A postweld heat treatment (PWHT, 700{degrees}C for 20 min in vacuum) under axial pressure (Ksi) was used to improve the joint strength consistency. The following conclusions can be drawn from this investigation: (1) A friction welding technique has been developed for joining titanium alloys (Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V) to Alloy 718 using an interlayer system of niobium and copper. Joint strengths averaging approximately 50 Ksi were achieved. (2) Deformation was concentrated in the interlayers, especially the copper interlayer, during friction welding. Increased reduction in length (RIL) during friction welding resulted in a decrease in the interlayer thicknesses. (3) The EDS results showed that the niobium and copper interlayers prevent interdiffusion between the two parent metals, producing formation of detrimental phases.

  15. Custom-made laser-welded titanium implant prosthetic abutment.

    PubMed

    Iglesia-Puig, Miguel A

    2005-10-01

    A technique to create an individually modified implant prosthetic abutment is described. An overcasting is waxed onto a machined titanium abutment, cast in titanium, and joined to it with laser welding. With the proposed technique, a custom-made titanium implant prosthetic abutment is created with adequate volume and contour of metal to support a screw-retained, metal-ceramic implant-supported crown. PMID:16198181

  16. 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.

  17. Microstructural evolution of pure copper during friction-stir welding

    NASA Astrophysics Data System (ADS)

    Mironov, S.; Inagaki, K.; Sato, Y. S.; Kokawa, H.

    2015-02-01

    The microstructural evolution of pure copper during friction-stir welding was found to be principally influenced by welding temperature. At temperatures below ~0.5 Tm (where Tm is melting point), the microstructure was shown to be essentially determined by continuous recrystallization, leading to significant grain refinement and related material strengthening in the stir zone. In contrast, grain structure development at temperatures above ~0.5 Tm was dominated by discontinuous recrystallization producing a relatively coarse grain structure in the stir zone and giving rise to material softening.

  18. 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.

  19. Effect of Surface Nanocrystallization on Fatigue Behavior of Pure Titanium

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Sun, Qiaoyan; Xiao, Lin; Sun, Jun

    2016-01-01

    The high-cycle fatigue behavior was investigated in pure titanium after surface nanocrystallization (SNC Ti). Compared with the coarse-grained titanium (CG Ti) samples, the SNC Ti samples exhibit an improved fatigue life. The SNC has a remarkable influence on the fatigue cracks initiation and growth of pure titanium. The results show that, because the free-surface cracking is suppressed by the surface nanogradient structure in the SNC Ti, the fatigue cracks initiation sites change from the free surface to the subsurface. Meanwhile, the fatigue crack growth rate decreases due to the microstructural feature and residual compressive stress. The deformation twins in the subsurface of SNC Ti have a marked effect on the fatigue crack initiation and the crack growth. The former effect is due to the twin boundaries being preferential sites for crack initiation, while the latter is associated with the barriers that the twin boundaries pose to the propagation of dislocations. Furthermore, microstructural analysis indicates that the dislocation distribution in SNC Ti gradually becomes homogenous as fatigue processes. This homogeneous microstructure is also beneficial to the improvement of fatigue life.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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. PMID:8004920

  5. 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.

  6. Pulsed Nd:YAG laser welding of titanium ear implants

    NASA Astrophysics Data System (ADS)

    Gedopt, Jan; Delarbre, Erwin

    2000-11-01

    Three different prototypes of ear implants have been successfully produced using Nd-YAG laser welding. The prototypes differ in use and dimensions. This presentation will deal with the latest developed ear implant, i.e. a box containing special electronics inside. The implant has to be He leak tight, the weld penetration should be between 50 and 65% of the cover in order to be sure to avoid damage of the electronics in the box and the temperature should not exceed 100 degree(s)C during welding. Furthermore no sharp edges and no surface contamination or oxidation is allowed. Pulsed Nd-YAG welding proved to be a fabrication technique who allowed satisfying those conditions. Through an appropriate choice of pulse energy, pulse time, pulse frequency, overlap and an external cooling device we succeeded to fulfil all those requirements. Special devices have been developed and are used to position the boxes adequately in front of the laser beam. During the welding a copper heat sink was used to eliminate the developed heat, and at the same time this was used to keep a good contact between the cover and the rest of the box. In the development phase the internal temperature during the welding cycle has been measured. With an appropriate choice of pulse frequency, pulse time, the internal temperature could be limited to about 80 degree(s)C. XPS measurements have also been performed on dummies in order to control the eventual formation of a titanium deposit during welding. Finally 30 implants have been welded successfully, and they will now be used for further medical tests, first on animals and later on human beings.

  7. 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. PMID:20126909

  8. Measurement of Work Hardening Behavior of Pure Titanium Sheet Using A Servo-Controlled Tube Bulge Testing Apparatus

    SciTech Connect

    Sumita, Takeshi; Kuwabara, Toshihiko; Hayashida, Yasuhiro

    2011-05-04

    Biaxial stress tests of rolled pure titanium sheet (JIS 1, 0.5 mm thick) have been carried out in order to investigate the anisotropic plastic deformation under biaxial tension. Rolled pure titanium sheet was bent and welded to make tubular specimens. Combined tension-internal pressure was applied to the tubular specimens using the servo-controlled tube bulge testing apparatus developed by one of the authors [Kuwabara, T., Yoshida, K., Narihara, K., Takahashi S., Int. J. Plasticity 21 (1), 101-117 (2002)], so that the strain rate ratio, {epsilon}{sub {phi}}:{epsilon}{theta}, in the axial ({phi}) and circumferential ({theta}) directions of the specimen was controlled to be constant. Contours of plastic work at different levels of plastic strain and stress paths under constant strain rate ratios have been observed in the first quadrant of stress space. It is found that the test material exhibits significant differential work hardening behavior with the increase of plastic work.

  9. Measurement of Work Hardening Behavior of Pure Titanium Sheet Using A Servo-Controlled Tube Bulge Testing Apparatus

    NASA Astrophysics Data System (ADS)

    Sumita, Takeshi; Kuwabara, Toshihiko; Hayashida, Yasuhiro

    2011-05-01

    Biaxial stress tests of rolled pure titanium sheet (JIS ♯1, 0.5 mm thick) have been carried out in order to investigate the anisotropic plastic deformation under biaxial tension. Rolled pure titanium sheet was bent and welded to make tubular specimens. Combined tension-internal pressure was applied to the tubular specimens using the servo-controlled tube bulge testing apparatus developed by one of the authors [Kuwabara, T., Yoshida, K., Narihara, K., Takahashi S., Int. J. Plasticity 21 (1), 101-117 (2002)], so that the strain rate ratio, ɛ˙φ:ɛ˙θ, in the axial (φ) and circumferential (θ) directions of the specimen was controlled to be constant. Contours of plastic work at different levels of plastic strain and stress paths under constant strain rate ratios have been observed in the first quadrant of stress space. It is found that the test material exhibits significant differential work hardening behavior with the increase of plastic work.

  10. 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.

  11. 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. PMID:8809260

  12. In vitro response of human fibroblasts to commercially pure titanium.

    PubMed

    Mostardi, R A; Meerbaum, S O; Kovacik, M W; Gradisar, I A

    1999-10-01

    The generation of metal particles through surface wear of prosthetic joints has been associated with biological reactions that may lead to prosthetic component loosening. The role of the macrophage in these reactions has been studied extensively, but that of the fibroblast has not. The few fibroblast studies that there have been have shown that particles of several metals, with sizes over a wide range, can promote cytokine release and may cause cell necrosis. The intent of this study was to determine if there are metal particle exposure threshold levels that result in morphological changes and cell necrosis of fibroblasts in peri-articular tissues. Retrieved human fibroblasts (superior medial plica) were cultured in standard fashion and then were exposed to various particle dosages of commercially pure Titanium (cpTi). Cell morphological changes and necrosis were observed to occur when the total mass of the particle dosage exceeded a threshold level. These data imply that these cell responses occur at threshold levels of wear particle exposure. PMID:10400881

  13. 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. PMID:25595723

  14. 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.

  15. 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.

  16. 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. PMID:11915624

  17. 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. PMID:19328274

  18. 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. PMID:20932119

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  1. 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.

  2. 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.

  3. Formation of Brittle Phases During Pulsed Current Gas Tungsten Arc Welding of Titanium to Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Wei, Shouzheng; Li, Yajiang; Wang, Juan; Liu, Kun

    2014-04-01

    Welding of titanium alloy TA15 to aluminum alloy Al 2024 was conducted by pulsed current gas tungsten arc welding using AlSi12 filler metal. Formation process of phases near the Ti/Al interface was discussed. Titanium and aluminum were partially fusion welded in the upper part while brazed together in the middle and bottom parts of the joint. In the upper part of the joint, intermetallics Ti3Al + Ti5Si3, TiAl + Ti5Si3, and TiAl3 were formed as three layers orderly from the titanium side to the weld metal. In the middle and bottom parts of the joint, intermetallics Ti5Si3 and TiAl3 were formed as two layers near the Ti/Al interface.

  4. 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. PMID:26046272

  5. 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.

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

    SciTech Connect

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

    2007-04-23

    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.

  7. 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. PMID:25579960

  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. Electron beam welding of titanium and Ti-6AL-4V Thick plates

    NASA Astrophysics Data System (ADS)

    Kohyama, Akira; Arata, Yoshiaki; Tomie, Michio; Igata, Naohiro

    1984-05-01

    This paper reports work as thick weld process development for Ti and Ti alloys in fusion reactor applications. The materials used are pure Ti and Ti-6A1-4V with a maximum plate thickness of 56 mm I-butt welded by a 100KW electron beam welding facility at Osaka University. Optimum welding conditions produced sound welded I-butt joints without detectable defects by X-ray when evaluated with tensile test and micro-Vickers hardness test. The microstructures of the welded joints were investigated with TEM and SEM. These results showed that welded joints were quite sound and were possibly acceptable as structural components of fusion reactor even in as welded state.

  10. 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.

  11. 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

    2016-04-01

    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.

  12. Structure of welded joints obtained by contact weld in nanostructured titanium

    NASA Astrophysics Data System (ADS)

    Klimenov, V. A.; Klopotov, A. A.; Gnysov, S. F.; Vlasov, V. A.; Lychagin, D. V.; Chumaevskii, A. V.

    2015-10-01

    The paper presents the research of the weld structure of two Ti specimens of the type VT6 that have nano- and submicrocrystalline structures. Electrical contact welding is used to obtain welds. The acicular structure is formed in the weld area. Two types of defects are detected, namely micropores and microcracks.

  13. 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.

  14. Fluid Flow Characteristics and Porosity Behavior in Full Penetration Laser Welding of a Titanium Alloy

    NASA Astrophysics Data System (ADS)

    Chang, Baohua; Allen, Chris; Blackburn, Jon; Hilton, Paul; Du, Dong

    2015-04-01

    In this paper, a computational fluid mechanics model is developed for full penetration laser welding of titanium alloy Ti6Al4V. This has been used to analyze possible porosity formation mechanisms, based on predictions of keyhole behavior and fluid flow characteristics in the weld pool. Numerical results show that when laser welding 3 mm thickness titanium alloy sheets with given laser beam focusing optics, keyhole depth oscillates before a full penetration keyhole is formed, but thereafter keyhole collapses are not predicted numerically. For lower power, lower speed welding, the fluid flow behind the keyhole is turbulent and unstable, and vortices are formed. Molten metal is predicted to flow away from the center plane of the weld pool, and leave a gap or void within the weld pool behind the keyhole. For higher power, higher speed welding, fluid flow is less turbulent, and such vortices are not formed. Corresponding experimental results show that porosity was absent in the melt runs made at higher power and higher welding speed. In contrast, large pores were present in melt runs made at lower power and lower welding speed. Based on the combination of experimental results and numerical predictions, it is proposed that porosity formation when keyhole laser welding may result from turbulent fluid flow behind the keyhole, with the larger the value of associated Reynolds number, the higher the possibility of porosity formation. For such fluid flow controlled porosities, measures to decrease Reynolds number of the fluid flow close to the keyhole could prove effective in reducing or avoiding porosity.

  15. [Preparation of anodic oxidation layer on the surface of pure titanium and its biological activity study].

    PubMed

    Gao, Shuchun; Zhai, Yuchun; Hu, Jinling

    2010-09-01

    This paper introduces how TiO2 film was prepared on pure titanium by anodic oxidation. Surface morphology and composition of the oxide film were analyzed by SEM coupled with EDAX. The deposition ability of hydroxyapatite of the anodized titanium in simulated body fluid (SBF) at 37 degrees C was evaluated. The results indicated that the oxide film was rough and honeycomb holes, connecting with each other, could be found on the surface. The holes with the diameter of 1-2 microm were distributed uniformly, which was typical for anodic oxidation. After alkaline treatment, hydroxyapatite deposition on the oxidized specimens in SBF was improved significantly. PMID:21179705

  16. 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.

  17. Mandibular reconstruction using autologous iliac bone and titanium mesh reinforced by laser welding for implant placement.

    PubMed

    Yamashita, Yoshio; Yamaguchi, Yoshimasa; Tsuji, Mitsuhiro; Shigematsu, Masahito; Goto, Masaaki

    2008-01-01

    Segmental mandibulectomy is a treatment option for benign and malignant neoplasms of the mandible. Although reconstructing the mandible of a patient with a missing segment is difficult, it is essential to improve the postoperative course of the patient. Mandibular reconstruction using titanium mesh is a useful technique for dental implant placement because the morphology of the mandible can be easily reproduced. However, fitting titanium mesh to the remaining mandible is not an easy task during surgery. The present report introduces a method in which a 3-dimensional skull model fabricated by means of stereolithography is prepared, based on computerized tomography (CT) scans, to construct a titanium mesh cage matching the shape of the mandible, preoperatively. Furthermore, the load-bearing area of the titanium mesh cage is reinforced by laser welding another layer of titanium mesh to reduce the incidence of metal fatigue during jaw movement. PMID:19216287

  18. 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.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

  1. 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.

  2. 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.

  3. Inverse Thermal Analysis of a Titanium Laser Weld Using Multiple Constraint Conditions

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    Inverse thermal analysis of a titanium laser weld 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 extends an inverse thermal analysis procedure applied in previous studies. This extension provides for the inclusion of constraint conditions associated with both solidification and phase transformation boundaries.

  4. 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. PMID:17937410

  5. 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.

  6. Microtextures and grain boundary misorientation distributions in controlled heat input titanium alloy fusion welds

    NASA Astrophysics Data System (ADS)

    Leary, R.; Merson, E.; Brydson, R.

    2010-07-01

    Microstructures, macrotextures and microtextures in commercial purity titanium and Ti-6Al-4V fusion welds produced by the InterPulse gas tungsten constricted arc welding (GTCAW) technique have been characterised. At the cooling rates associated with the InterPulse technique, α variants sharing a common 1120 pole are found to cluster together into groups within prior β grains, leading to large areas where all variants are separated by a misorientation of 60°. These present potential easy slip paths, hence increasing the "effective structural unit size." Characterisation of these microtextures may provide new insight into microtexture-properties relations and the mechanisms of microtextural evolution.

  7. Bonding of low-fusing dental porcelain to commercially pure titanium.

    PubMed

    Könönen, M; Kivilahti, J

    1994-09-01

    The objective of the investigation was to study the basic problems related to the firing of dental porcelain to commercially pure titanium. The firing of a low-fusing porcelain to sandblasted or electrolytically polished titanium was carried out in an ordinary dental furnace. The interfacial regions between the ceramic coatings and titanium were analyzed using scanning acoustic microscopy (C-SAM) and scanning electron microscopy (SEM) techniques. Thermal stresses in the joints were evaluated by means of a finite element model based on multilayer elastic strain analysis. The chemical reactions and their formation sequence at 750 degrees C was predicted thermodynamically and observed experimentally both at 750 and 800 degrees C. The C-SAM results gave evidence that the integrity of the porcelain-titanium joints are better in the sandblasted samples than in the electropolished ones, where defects were larger. SEM analyses of the same samples confirmed the C-SAM findings. Because the reaction layers are more continuous in the electropolished samples, cracks propagated more readily in these samples during the cooling procedure. Both thermodynamic calculations and experimental chemical analyses strongly indicate that the cause for the cracking of the reaction zone is thin layer of Ti (oxo)silicide and/or a relatively thick solid solution layer of Ti and oxygen. PMID:7814430

  8. MC3T3-E1 Cell Response to Pure Titanium, Zirconia and Nano-Hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Hwan; Han, Jung-Suk; Yang, Jae-Ho; Lee, Jai-Bong; Kim, Dae-Joon

    Titanium, zirconia and HAp were known as good biocompatible materials for tissue engineering. Osteblastic cell response is influence by the surface topography of material and its chemical composition as well. To evaluate the influence of different chemical compositions on osteoblast-like cells the specimens were polished until they have almost identical surface roughness. The commercially pure titanium, zirconia/alumina composite and nano-sized hydroxyapatite (HAp) specimens synthesized by hydrothermal method were used to evaluate the cell attachment, proliferation and differentiation. Confocal laser microscopy was used measurement of surface roughness, and flourescence microscopy and SEM were used to evaluate initial cell attachment and morphology after 3 hours. MTS assay was performed for cell proliferation after 1, 3, 7 days and ALP assay was used for cell differentiation after 7, 10, 14 days of cell culture period. Surface topography of nano-HAp specimen was almost identical compared with those of titanium and zirconia specimen. Under this condition, proliferation and differentiation of MC3T3-E1 cells was not significantly different with those on titanium and zirconia specimen. However, cells on Nano-HAp specimen showed quicker and more active cellular reaction for attachment when measured by the expression of adhesion proteins through confocal laser microscopy. The results suggested that the new nano-sized HAp can be applied as a suitable material for skeletal tissue engineering.

  9. 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.

  10. 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. PMID:12238790

  11. 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.

  12. Fusion zone microstructure and porosity in electron beam welds of an {alpha} + {beta} titanium alloy

    SciTech Connect

    Mohandas, T.; Banerjee, D.; Kutumba Rao, V.V.

    1999-03-01

    The effect of electron beam welding parameters on fusion zone (FZ) microstructure and porosity in a Ti-6.8 Al-3.42 Mo-1.9 Zr-0.21 Si alloy (Russian designation VT 9) has been investigated. It has been observed that the FZ grain width increased continuously with increase in heat input when the base metal was in the {beta} heat-treated condition, while in the {alpha} + {beta} heat-treated base metal welds, the FZ grain width increased only after a threshold energy input. The difference is attributed to both the weld thermal cycle and the pinning effect of equiaxed primary alpha on grain growth in the heat-affected zone (HAZ) of {alpha} + {beta} heat-treated base metal. Postweld heat treatment (PWHT) in the subtransus and supertransus regions did not alter the columnar grain morphology in the FZ, possibly due to the lack of enough driving force for the formation of new grains by the breaking up of the columnar grains and grain boundary movement for grain growth. The highest porosity was observed at intermediate welding speeds. At low speeds, a majority of pores formed at the fusion boundary, while at high speeds, occurrence of porosity was maximum at the weld center. The trends on porosity can be explained on the basis of solubility of hydrogen in titanium as a function of temperature and the influence of weld thermal cycle on nucleation, growth, and escape of hydrogen gas bubbles. The porosity at slow welding speeds is low because sufficient time exists for the nucleation, growth, and escape of hydrogen gas bubbles, while insufficient time exists for the nucleation of gas bubbles at high welding speeds. The effect of pickling of joint surface, vacuum annealing of the base metal, and successive remelting of the weld metal has also been investigated.

  13. 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. PMID:24757071

  14. Success and high predictability of intraorally welded titanium bar in the immediate loading implants.

    PubMed

    Fogli, Vaniel; Camerini, Michele; Lauritano, Dorina; Carinci, Francesco

    2014-01-01

    The implants failure may be caused by micromotion and stress exerted on implants during the phase of bone healing. This concept is especially true in case of implants placed in atrophic ridges. So the primary stabilization and fixation of implants are an important goal that can also allow immediate loading and oral rehabilitation on the same day of surgery. This goal may be achieved thanks to the technique of welding titanium bars on implant abutments. In fact, the procedure can be performed directly in the mouth eliminating possibility of errors or distortions due to impression. This paper describes a case report and the most recent data about long-term success and high predictability of intraorally welded titanium bar in immediate loading implants. PMID:24963419

  15. Success and High Predictability of Intraorally Welded Titanium Bar in the Immediate Loading Implants

    PubMed Central

    Fogli, Vaniel; Camerini, Michele; Carinci, Francesco

    2014-01-01

    The implants failure may be caused by micromotion and stress exerted on implants during the phase of bone healing. This concept is especially true in case of implants placed in atrophic ridges. So the primary stabilization and fixation of implants are an important goal that can also allow immediate loading and oral rehabilitation on the same day of surgery. This goal may be achieved thanks to the technique of welding titanium bars on implant abutments. In fact, the procedure can be performed directly in the mouth eliminating possibility of errors or distortions due to impression. This paper describes a case report and the most recent data about long-term success and high predictability of intraorally welded titanium bar in immediate loading implants. PMID:24963419

  16. 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.

  17. Application of commercially pure titanium coatings using HVOF thermal spray for machinery component restoration

    SciTech Connect

    McCaw, R.L.; Hays, R.A.; Brenna, R.T.

    1994-12-31

    Alloy 625 has been shown to be susceptible to crevice corrosion under tight metal to nonmetal crevices in both natural and treated seawater. Under similar conditions, commercially pure titanium (CP Ti) has been shown to be immune. Therefore, coating alloy 625 sealing areas with CP Ti is a potentially effective crevice corrosion countermeasure. Specialized thermal spray techniques were developed utilizing the high velocity oxy-fuel (HVOF) process to apply coatings of CP Ti to alloy 625 substrates in atmosphere. Coating quality was similar to plasma sprayed coatings of other less reactive, metals. Crevice corrosion tests were conducted and issues relating to implementation of HVOF thermal spraying on a production basis were considered.

  18. 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.

  19. 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

  20. 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. PMID:26666885

  1. 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.

  2. 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.

  3. 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. PMID:22652178

  4. Fusion zone microstructure and porosity in electron beam welds of an α+β titanium alloy

    NASA Astrophysics Data System (ADS)

    Mohandas, T.; Banerjee, D.; Kutumba Rao, V. V.

    1999-03-01

    The effect of electron beam welding parameters on fusion zone (FZ) microstructure and porosity in a Ti -6.8 Al -3.42 Mo -1.9 Zr -0.21 Si alloy (Russian designation VT 9) has been investigated. It has been observed that the FZ grain width increased continuously with increase in heat input when the base metal was in the β heat-treated condition, while in the α+β heat-treated base metal welds, the FZ grain width increased only after a threshold energy input. The difference is attributed to both the weld thermal cycle and the pinning effect of equiaxed primary alpha on grain growth in the heat-affected zone (HAZ) of α+β heat-treated base metal. Postweld heat treatment (PWHT) in the subtransus and supertransus regions did not alter the columnar grain morphology in the FZ, possibly due to the lack of enough driving force for the formation of new grains by the breaking up of the columnar grains and grain boundary movement for grain growth. As the PWHTs were conducted in a furnace, the role of thermal gradients can be ruled out. Intragranular microstructure in the aswelded condition consisted of hexagonal martensite. The scale of the martensite laths depended on welding speed. The highest porosity was observed at intermediate welding speeds. At low speeds, a majority of pores formed at the fusion boundary, while at high speeds, occurrence of porosity was maximum at the weld center. The trends on porosity can be explained on the basis of solubility of hydrogen in titanium as a function of temperature and the influence of weld thermal cycle on nucleation, growth, and escape of hydrogen gas bubbles. The porosity at slow welding speeds is low because sufficient time exists for the nucleation, growth, and escape of hydrogen gas bubbles, while insufficient time exists for the nucleation of gas bubbles at high welding speeds. The effect of pickling of joint surface, vacuum annealing of the base metal, and successive remelting of the weld metal has also been investigated.

  5. 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.

  6. Elevated temperature behavior of superplastically formed/weld-brazed titanium compression panels having advanced shaped stiffeners

    NASA Technical Reports Server (NTRS)

    Royster, D. M.; Bales, T. T.

    1983-01-01

    The 316 C (600 F) buckling behavior of superplastically formed/weld-brazed titanium compression panels having advanced shaped stiffeners was investigated. Fabrication of the advanced shaped stiffeners was made possible by the increased formability afforded by the superplasticity characteristics of the titanium alloy Ti-6Al-4V. Stiffeners having the configurations of a conventional hat, a beaded web, a modified beaded web, a ribbed web, and a stepped web were investigated. The data from the panel tests include load-shortening curves, local buckling strengths, and failure loads. The superplastic formed/weld-brazed panels with the ribbed web and stepped web stiffeners developed 25 and 27 percent higher buckling strengths at 316 C (600 F) than panels with conventionally shaped stiffeners. The buckling load reductions for panels tested at 316 C (600 F), compared with panels tested at room temperature, were in agreement with predictions based on titanium material property data. The advantage that higher buckling loads can be readily achieved by superplastically forming of advanced stiffener shapes was demonstrated. Application of these advanced stiffener shapes offers the potential to achieve substantial weight savings in aerospace vehicles.

  7. Cell attachment of periodontal ligament cells on commercially pure titanium at the early stage.

    PubMed

    Zhou, Bin; Cao, Yingguang; Wu, Lijuan; Yuan, Yanxiang; Zeng, Yinping

    2004-01-01

    In order to study the character of periodontal ligament cells (PDLCs) attaching on commercially pure titanium (cpTi) by morphology and metrology on the early stage (24 h), 1 x 10(5)/ml PDLCs in 2 ml culture medium were seeded on cpTi discs fixed in 24-well culture plates. Morphology of cell attachment was observed by contrast phase microscope, scanning electron microscope (SEM) and fluroscence microscopy. Cell adhesion was analyzed by MTT at 0.5, 1, 2, 4 h respectively. PDLCs could attach and spread on cpTi discs. SEM showed that PDLCs had pseudopod-like protuberance. PDLCs showed different attaching phases and reached saturation in cell number at 2 h. It was concluded that PDLCs had good biocompatibility with cpTi, and showed a regular and dynamic pattern in the process of attaching to cpTi. PMID:15315359

  8. 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

  9. 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. PMID:25579920

  10. Hardness, microstructure and surface characterization of laser gas nitrided commercially pure titanium using high power CO{sub 2} laser

    SciTech Connect

    Selvan, J.S.; Subramanian, K.; Nath, A.K.; Gogia, A.K.; Balamurugan, A.K.; Rajagopal, S.

    1998-10-01

    Surface nitriding of commercially pure (CP) titanium was carried out using high power CO{sub 2} laser at pure nitrogen and dilute nitrogen (N{sub 2} + Ar) environment. The hardness, microstructure, and melt pool configuration of the laser melted titanium in helium and argon atmosphere was compared with laser melting at pure and dilute nitrogen environment. The hardness of the nitrided layer was of the order of 1000 to 1600 HV. The hardness of the laser melted titanium in the argon and helium atmosphere was 500 to 1000 HV. Using x-ray analysis of the formation of TiN and Ti{sub 2}N phase was identified in the laser nitrided titanium. The presence of nitrogen in the nitrided zone was confirmed using secondary ion mass spectroscopy (SIMS) analysis. The microstructures revealed densely populated dendrites in the sample nitrided at 100% N{sub 2} environment and thinly populated dendrites in dilute environment. The crack intensity was large in the nitrided sample at pure nitrogen, and few cracks were observed in the 50% N{sub 2} + 50% Ar environment.

  11. A Quantitative Model of Keyhole Instability Induced Porosity in Laser Welding of Titanium Alloy

    NASA Astrophysics Data System (ADS)

    Pang, Shengyong; Chen, Weidong; Wang, Wen

    2014-06-01

    Quantitative prediction of the porosity defects in deep penetration laser welding has generally been considered as a very challenging task. In this study, a quantitative model of porosity defects induced by keyhole instability in partial penetration CO2 laser welding of a titanium alloy is proposed. The three-dimensional keyhole instability, weld pool dynamics, and pore formation are determined by direct numerical simulation, and the results are compared to prior experimental results. It is shown that the simulated keyhole depth fluctuations could represent the variation trends in the number and average size of pores for the studied process conditions. Moreover, it is found that it is possible to use the predicted keyhole depth fluctuations as a quantitative measure of the average size of porosity. The results also suggest that due to the shadowing effect of keyhole wall humps, the rapid cooling of the surface of the keyhole tip before keyhole collapse could lead to a substantial decrease in vapor pressure inside the keyhole tip, which is suggested to be the mechanism by which shielding gas enters into the porosity.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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. PMID:21077419

  17. Quantitatively Analyzing Strength Contribution vs Grain Boundary Scale Relation in Pure Titanium Subjected to Severe Plastic Deformation

    NASA Astrophysics Data System (ADS)

    Luo, Peng; Hu, Qiaodan; Wu, Xiaolin

    2016-05-01

    Electron backscatter diffraction was used to reveal high- and low-angle grain boundaries (HAGBs, with misorientation ≥15 deg, and LAGBs, <15 deg) in pure titanium (ASTM grade 2) subjected to equal channel angular pressing. Comprehensive paradigms were developed to present relations of yield strength vs HAGB grain diameter, and LAGB contribution vs LAGB linear intercept. Incorporating grain orientations (against loading axis) into the Hall-Petch relation, we quantitatively investigated the strength contributions by HAGBs and LAGBs, respectively.

  18. Tribological characterization of surface-treated commercially pure titanium for femoral heads in total hip replacement: a feasibility study.

    PubMed

    Cotogno, G; Holzwarth, U; Franchi, M; Rivetti, S; Chiesa, R

    2006-12-01

    Most noncemented total hip replacements combine a titanium alloy stem, a CoCrMo femoral head and an ultra-high molecular weight polyethylene (UHMWPE) acetabular cup. In spite of its nickel content of up to 1% and the resulting biocompatibility issues in some clinical situations, the higher cost and some difficulties in machining, CoCrMo alloy is preferred to titanium alloys thanks to its outstanding tribological properties, higher hardness and elastic modulus. Nowadays most of the heads of hip prostheses use CoCrMo as bearing material. The present study investigates the effect of various surface treatments and combinations of treatments, such as electrochemical oxidation (anodization), laser surface melting and barrel polishing, on the tribological properties of commercially pure grade 2 titanium. The aim of the study was to characterize surface treatments capable of improving the tribological properties of titanium surface to the same extent as CoCrMo. The tribological properties were characterized by multidirectional pin-on-flat screening wear tests, using UHMWPE pins as bearing surface. The experiments showed the possibility of improving the wear resistance of titanium to the degree of CoCrMo. Although further efforts will be required to optimize the treatments studied, the results are encouraging enough to warrant pursuing this direction of investigation. PMID:17219358

  19. 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.

  20. 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.

  1. 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. PMID:26963213

  2. Combination of laser keyhole and conduction welding: Dissimilar laser welding of niobium and Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Torkamany, M. J.; Malek Ghaini, F.; Poursalehi, R.; Kaplan, A. F. H.

    2016-04-01

    Pulsed Nd:YAG laser welding of pure niobium plate to titanium alloy Ti-6Al-4V sheet in butt joint is studied regarding the laser/metal interaction modes. To obtain the optimized process parameters in dissimilar welding of Ti-6Al-4V/Nb, the melting ratio of laser beam energy for each weld counterpart is evaluated experimentally. Different laser welding modes of keyhole and conduction are predicted regarding the absorbed energy from the similar laser pulses on each weld counterpart. Laser keyhole and conduction welding were observed simultaneously through direct visualization of laser interaction with dissimilar metals using High Speed Imaging (HSI) system.

  3. 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.

  4. 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. PMID:16721459

  5. 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. PMID:23430335

  6. Concentration-driven phase control for low temperature synthesis of phase-pure anatase and rutile titanium oxide.

    PubMed

    Wang, Zhifeng; Xiao, Chunyan; Yamada, Shuhei; Yoshinaga, Kohji; Bu, Xiu R; Zhang, Ming

    2015-06-15

    It is highly desirable to develop controlled synthetic methods at low temperature (<100 °C) for defined phases of titanium oxide nanoparticle. We present here a simple low temperature approach which is based on the peroxide route. This approach allows the preparation of phase-pure rutile and anatase without the use of any additives or surfactants or external acids. The formation of crystalline phases is found to be dependent on reaction temperature and highly dependent on concentration. Phase-pure rutile is obtained in two concentration zones while phase-pure anatase is obtained in one concentration zone. The relationship between phases and reaction conditions (concentration and temperature) fits well with the nucleation diffusion rate model. PMID:25746180

  7. Ultrafine-grained commercially pure titanium and microstructure response to hydroxyapatite coating methods

    NASA Astrophysics Data System (ADS)

    Calvert, Kayla L.

    Commercially pure titanium (cp-Ti) is an ideal biomaterial as it does not evoke an inflammatory foreign body response in the body. However, the low strength of cp-Ti prevents the use in most orthopaedic load bearing applications. Therefore, many metal orthopaedic implants are commonly made of higher strength metal alloys that are less biocompatible. Nanostructured materials exhibit superior mechanical properties compared to their conventional grain sized counterparts. Severe plastic deformation (SPD) of metals has been shown to produce nanostructured materials. SPD by machining is a single-step deformation route that refines the grain microstructure, to develop an ultrafine grained (UFG) microstructure. UFG cp-Ti strips were developed with induced shear strains of up to 4.0 using a machining-based process. Both Vickers microhardness evaluation and microstructural analysis were used to characterize the as-received (annealed) and machined states. For induced shear strains between 1.9 and 4.0 in grade 2 cp-Ti the hardness was increased from 188 +/- 7 kg/mm2 in the as-received state to between 244 +/- 6 and 264 +/- 12 kg/mm 2 in the as-machined state, corresponding to an increase in hardness between 31 and 41%. The microstructural analysis revealed a grain size reduction from 34 +/- 11 mum in the as-received state to ˜ 100 nm for machined grade 2-Ti. A complete annealing study suggested that recovery/recrystallization occurs between 300 and 400°C, with a significant hardness drop between 400 and 600°C, while grain growth is continuous, starting at the lowest annealing temperature of 300°C. Hydroxyapatite (HA) is commonly applied to orthopaedic devices to promote bone growth. Machined Ti strips were coated with HA using conventional plasma spray as well as two alternative low-temperature application routes (sol-gel with calcination and anodization with hydrothermal treatment) to evaluate the thermal influence on the UFG-Ti substrate. Plasma spray produced a thick

  8. Influence of the method of protection on the cyclic strength and character of fracture of titanium alloy weld joints

    SciTech Connect

    Mozeiko, B.Y.; Yakovleva, T.Y.

    1985-10-01

    In the argon-arc welding of titanium assemblies of complex spatial configuration done outside controlled atmosphere chambers it is often difficult to provide reliable protection of the root side of the joint with known gas protection equipment. The necessary reliability in protection is provided by a special, technologically stable two-layer coating applied to the reverse side of the edges being welded. The inner forming layer of the coating is a powder mixture of halides of alkali and alkaline-earth metals thinned to a pasty state with an ethanol-acetone solvent. The outer reinforcing layer is a solution of BMK5 acrylic resin in ethanol-acetone solvent. For a comparative evaluation of the cyclic strength of weld joints obtained with two methods of protection of the reverse side of the joint (protective coating and highest purity argon), two lots of specimens were tested in alternating-sign symmetric bending. Flat weld specimens of 2-mm-thick VT20 titanium sheet were tested.

  9. 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

  10. 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…

  11. 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. PMID:26706544

  12. The influence of nickel layer thickness on microhardness and hydrogen sorption rate of commercially pure titanium alloy

    NASA Astrophysics Data System (ADS)

    Kudiiarov, V. N.; Kashkarov, E. B.; Syrtanov, M. S.; Yugova, I. S.

    2016-02-01

    The influence of nickel coating thickness on microhardness and hydrogen sorption rate by commercially pure titanium alloy was established in this work. Coating deposition was carried out by magnetron sputtering method with prior ion cleaning of surface. It was shown that increase of sputtering time from 10 to 50 minutes leads to increase coating thickness from 56 to 3.78 μm. It was established that increase of nickel coating thickness leads to increase of microhardness at loads less than 0.5 kg. Microhardness values for all samples are not significantly different at loads 1 kg. Hydrogen content in titanium alloy with nickel layer deposited at 10 and 20 minutes exceeds concentration in initial samples on one order of magnitude. Further increasing of deposition time of nickel coating leads to decreasing of hydrogen concentration in samples due to coating delamination in process of hydrogenation.

  13. 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

  14. 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°.

  15. 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.

  16. 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.

  17. Fatigue performance of joints executed in pure titanium structures with several diameters.

    PubMed

    Nuñez-Pantoja, Juliana Maria Costa; Vaz, Luis Geraldo; Nóbilo, Mauro Antônio de Arruda; Mesquita, Marcelo Ferraz

    2011-01-01

    This study evaluated fatigue strength of CP-Ti laser-welded joints. Sixty (20/diameter) CP-Ti casted dumbbell rods with diameters of 1.5, 2.0, and 3.5 mm were sectioned and welded using two joint openings (0.0 (00) and 0.6 mm (06)). Six groups were formed, amounting to a total of 9 (n=10) with inclusion of intact groups. Welding was executed using 360 V/8 ms (1.5 and 2.0 mm) and 380 V/9 ms (3.5 mm). Joints were finished, polished, and submitted to radiographic examination to visually analyze presence of porosity (PP). Specimens were submitted to cyclic tests, and the number of cycles until failure (NC) was recorded. Fractured surfaces were examined by SEM. Kruskal-Wallis and Dunn (α=0.05) tests demonstrated that NC was lower for all diameters with 06, and for 3.5 mm/00. NC and PP were found to have a negative correlation (Spearman Coefficient). For CP-Ti frameworks with thin diameters, laser welding is better when structures are juxtaposed. PMID:22123013

  18. 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.

  19. 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.

  20. 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. PMID:26952502

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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. PMID:23775939

  8. Structure, castability and mechanical properties of commercially pure and alloyed titanium cast in graphite mould.

    PubMed

    Cheng, W W; Ju, C P; Lin, J H Chern

    2007-07-01

    This report is a study of structure, castability, mechanical properties as well as corrosion behaviour of titanium doped with up to 5 weight percentage (wt%) of a series of alloy elements, including Ta, Mo, Nb, Hf, Zr, Sn, Bi and Ag. The results indicate that, with addition of 1 wt% alloy element, Bi and Mo were most effective in enhancing the castability of titanium. With more alloy elements added, the castability values of most alloys more or less decreased. Except Ti-Mo system, all Ti alloys with a fine acicular morphology had the same crystal structure (hcp) as that of c.p. Ti with a typical lath type morphology. When 3 wt% or more Mo was added, a finer orthorhombic alpha'' phase was formed. The microhardness and bending strength values of Ti alloys were all higher than those of c.p. Ti. Among all alloys, Ti-Mo system exhibited the highest hardness and strength level. For a certain alloy, the bending strength did not necessarily increase with its alloy content. Except Ti-5Zr and Ti-Mo alloys, the bending moduli of most alloy systems were not much different from that of c.p. Ti. All alloys showed an excellent resistance to corrosion in Hanks' solution at 37 degrees C. PMID:17559621

  9. Corrosion and Tribocorrosion Performance of Thermally Oxidized Commercially Pure Titanium in a 0.9% NaCl Solution

    NASA Astrophysics Data System (ADS)

    Bailey, R.; Sun, Y.

    2015-04-01

    In the present work, the corrosion and tribocorrosion characteristics of thermally oxidized commercially pure titanium in a 0.9% NaCl solution have been investigated. Thermal oxidation (TO) of CP-Ti was carried out at a temperature of 625 °C for 20 h. This treatment results in a multi-layered structure consisting of a 1 µm rutile (TiO2) film and a 9 µm α-titanium oxygen diffusion zone (ODZ) (α-Ti(O)). Electrochemical tests were carried out on surfaces created at various depths from the TO-Ti original surface. It was found that the rutile film generated through TO offers excellent corrosion resistance over that of untreated Ti. Testing also provided evidence that oxygen content in the upper part of the ODZ (depths <5 µm from the surface) helps accelerate passive film formation and thus reduce the corrosion of CP-Ti. Tribo-electrochemical testing of TO-Ti was carried out against an alumina counter face under a load of 2 N and various anodic and cathodic potentials. It is initially shown that the rutile oxide layer offers both low friction and much better resistance to material removal during tribocorrosion than untreated CP-Ti. During sliding wear at open circuit potential, four frictional zones can be identified in a typical friction curve, each having its own characteristics corresponding to the oxide layer, the gradual or partial removal of the oxide layer, the diffusion zone, and the substrate. An unusual anodic protection behavior of the oxide film has also been observed. When the TO-Ti is polarized anodically during sliding, the durability of the oxide layer is prolonged, resulting in low friction and much reduced material loss. When cathodically charged to -1500 mVSCE during sliding, both the TO-Ti and untreated CP-Ti experience a reduction in material loss. This is believed to be related to hydrogen evolution and titanium hydride formation.

  10. 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.

  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. 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.

  13. Effect of heat treatment and diffusion welding conditions on the structure and properties of porous material workpieces made of titanium fibers

    NASA Astrophysics Data System (ADS)

    Kollerov, M. Yu.; Shlyapin, S. D.; Gusev, D. E.; Senkevich, K. S.; Runova, Yu. E.

    2015-11-01

    The effect of the diffusion welding conditions on the structure and properties of a porous material (PM) made of titanium fibers is studied. It is shown that the use of fibers produced by melt quenching and then joined to form workpieces or articles by diffusion welding can be a promising trend in the production of PMs for medicine applications. A change in the solidification rate of fibers and their contact substantially affects the mechanical properties of PM workpieces. As the diffusion welding temperature of both sheet and cylindrical workpieces increases, the strength of PM increases and the plasticity of PM decreases.

  14. 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.

  15. Synthesis of nitrogen doped faceted titanium dioxide in pure brookite phase with enhanced visible light photoactivity.

    PubMed

    Pan, Jian; Jiang, San Ping

    2016-05-01

    Brookite titanium dioxide (TiO2) is rarely studied, as compared with anatase and rutile phases TiO2, due to its comparatively lower photoactivity. It has been recently reported that brookite TiO2 with active facets exhibits excellent performance, however, synthesis of such faceted brookite TiO2 is difficult because of its low thermodynamic phase stability and low structural symmetric. Furthermore, like faceted anatase and rutile TiO2, faceted brookite TiO2 is not responsive to visible light due to its wide bandgap. In this study, a novel dopant, hydrazine, was introduced in the development of nitrogen doping. By applying this dopant, nitrogen doped brookite nanorods with active {120}, {111} and {011¯} facets were successfully synthesized. The resultant materials exhibited remarkably enhanced visible-light photoactivity in photodegradation. PMID:26866886

  16. Standard specification for seamless and welded titanium and titanium alloy tubes for condensers and heat exchangers. ASTM standard

    SciTech Connect

    1998-09-01

    DoD adopted. This specification is under the jurisdiction of ASTM Committee B-10 on Reactive and Refractory Metals and Alloys and is the direct responsibility of Subcommittee B10.01 on Titanium. Current edition approved Apr. 10, 1998 and published September 1998. Originally published as B 388-58T. Last previous edition was B 388-95.

  17. 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.

  18. A comparative study of the influence of three pure titanium plates with different micro- and nanotopographic surfaces on preosteoblast behaviors.

    PubMed

    Zuo, Jun; Huang, Xunzhi; Zhong, Xiaoxia; Zhu, Bangshang; Sun, Qiang; Jin, Chengyu; Quan, Hongzhi; Tang, Zhangui; Chen, Wantao

    2013-11-01

    There is a great demand for dental implants with the ability to accelerate periimplant bone regeneration. Modification of surface micro- and nanotopographies has been revealed to affect bone cell metabolism. In this study, we utilized dielectric barrier discharge (DBD) technology to modify commercially pure titanium (Ti-tr) surfaces and then investigated the cytocompability of DBD-modified Ti surface when compared with machined (Ti-m) and polished (Ti-p) Ti surfaces. These three kinds of Ti plates exhibited different surface energies and topographies at the micro- and nanoscale levels. The DBD-treated pure Ti surface significantly enhances cell adhesion, spread, and proliferation of MC3T3-E1 preosteoblast cells compared with the Ti-p and Ti-m surfaces, suggesting that Ti-tr has better cytocompatibility compared with the other two surfaces. Preosteoblast cells on Ti-m surface exhibited higher alkaline phosphatase activity than cells on Ti-tr and Ti-p surfaces 14 days after seeding. No significant difference in alkaline phosphatase activity was observed between cells grown on Ti-tr and Ti-p surfaces. Our study demonstrated that DBD modification significantly enhanced cell adhesion, spread, and proliferation of preosteoblasts with no negative effects on cell differentiation. Microtopography and nanotopography of the surfaces of different materials and chemical/energetic properties have a synergistic effect on cell attachment, proliferation, and differentiation. PMID:23625827

  19. 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. PMID:20459192

  20. 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.

  1. 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. PMID:25020216

  2. Physical Simulation of Hot Rolling of Ultra-fine Grained Pure Titanium

    NASA Astrophysics Data System (ADS)

    Polyakov, Alexander; Gunderov, Dmitry; Sitdikov, Vil'; Valiev, Ruslan; Semenova, Irina; Sabirov, Ilchat

    2014-12-01

    Complex thermo-mechanical processing routes are often developed for fabrication of ultra-fine grained (UFG) metallic materials with superior mechanical properties. The processed UFG metallic materials often have to undergo additional metalforming operations for fabrication of complex shape parts or tools that can significantly affect their microstructure and crystallographic texture, thus further changing their mechanical properties. The development of novel thermo-mechanical processing routes for fabrication of UFG metallic materials or for further metalforming operations is very time-consuming and expensive due to much higher cost of the UFG metallic materials. The objective of this work is to perform physical simulation of hot rolling of UFG pure Ti obtained via severe plastic deformation and to analyze the effect of hot rolling on the microstructure, crystallographic texture, and hardness of the material. It is demonstrated that physical simulation of metalforming processes for UFG metallic materials can significantly reduce the amount of material required for development of processing routes as well as to increase the efficiency of experimental work.

  3. 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.

  4. Surface analysis of commercially pure titanium implant retrieved from rat bone. Part 1: initial biological response of sandblasted surface.

    PubMed

    Watanabe, Kouichi; Okawa, Seigo; Kanatani, Mitugu; Homma, Kikuo

    2009-03-01

    To gain insight on the early biological response to commercial pure titanium (cpTi), the surface properties of cpTi implants retrieved from rat bone were examined by X-ray photoelectron spectroscopy (XPS). To this end, semi-cylindrical bullets, 1.1 mm in diameter and 3.5 mm in length, were implanted into the femurs of Wistar rats and then retrieved after either 3 hours or 7 days. Regardless of implantation interval, elements of Ti, O, C, and N were observed on the retrieved implants and that the thickness of the adsorbed film (mainly protein) was estimated to be about 2.5 nm. Small amounts of both Ca and P were also detected, whereby the Ca/P atomic ratios after 3 hours and 7 days were very small compared to that of hydroxyapatite. Furthermore, no correlation was found between the Ca and P distributions in the element maps. In conclusion, no calcium phosphate compounds were formed on the implant in vivo after 7 days. PMID:19496397

  5. Corrosion behaviour of commercially pure titanium shot blasted with different materials and sizes of shot particles for dental implant applications.

    PubMed

    Aparicio, Conrado; Gil, F Javier; Fonseca, Carlos; Barbosa, Mario; Planell, Josep Anton

    2003-01-01

    It is well known that the osseointegration of the commercially pure titanium (c.p. Ti) dental implant is improved when the metal is shot blasted in order to increase its surface roughness. This roughness is colonised by bone, which improves implant fixation. However, shot blasting also changes the chemical composition of the implant surface because some shot particles remain adhered on the metal. The c.p. Ti surfaces shot blasted with different materials and sizes of shot particles were tested in order to determine their topographical features (surface roughness, real surface area and the percentage of surface covered by the adhered shot particles) and electrochemical behaviour (open circuit potential, electrochemical impedance spectroscopy and cyclic polarisation). The results demonstrate that the increased surface area of the material because of the increasing surface roughness is not the only cause for differences found in the electrochemical behaviour and corrosion resistance of the blasted c.p. Ti. Among other possible causes, those differences may be attributed to the compressive residual surface stresses induced by shot blasting. All the materials tested have an adequate corrosion and electrochemical behaviour in terms of its possible use as dental implant material. PMID:12419627

  6. 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.

  7. 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.

  8. Marginal adaptation of cast partial crowns made of pure titanium and a gold alloy under influence of a manual burnishing technique.

    PubMed

    Stoll, R; Makris, P; Stachniss, V

    2001-05-01

    The aim of this study was to determine the marginal adaptation of partial crowns from pure titanium and a gold alloy after two different cementation techniques. Forty freshly extracted human molars were prepared and randomly divided in four groups. Two groups were restored with partial crowns using the gold alloy Degulor M*. In one group, the crowns were fixed on the tooth by using a zinc phosphate cement. In the other group the margins were additionally burnished by using a hand burnisher No. 660. In the other two groups, partial crowns from pure titanium were cemented in the same way. The marginal quality was determined by quantitative margin analysis in the SEM using a replica technique. Partial crowns from a gold alloy showed significantly (P < 0.05) more margin quality A (vertical marginal discrepancy < 50 microm) while partial crowns from pure titanium had significantly (P < 0.05) more margin quality B (vertical marginal discrepancy 50-100 microm) and over-extended margins (quality D). No significant (P < 0.05) difference was found between the conventional cementation technique and the technique with manual burnishing in both material groups. PMID:11380778

  9. MHD technologies for electroslag welding and melting of titanium alloys for aerospace industry

    NASA Astrophysics Data System (ADS)

    Shcherbinin, E.; Kompan, Ya.

    2006-09-01

    The basic tendency in improving titanium alloys is the need to increase the specific strength of structures of the aerospace engineering. Owing to the strength of advanced alloys Ti­10­2­3 (the USA) and VT22 (Russia), reaching 1300­1400 MPA, titanium is used widely in the load­carrying airframes and most loaded parts of engines of the modern airplanes "Boeing", "Airbus", "Antonov", "Ilyushin ", and others. At present, the problem is to develop alloys with a tensile strength of 1600 MPa and higher. Figs 2, Refs 6.

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

    PubMed Central

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

    2015-01-01

    PURPOSE To compare the shear bond strength of various veneering materials to grade II commercially pure titanium (CP-Ti). MATERIALS AND METHODS 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. RESULTS 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. CONCLUSION 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. PMID:25722841

  11. 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

  12. 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

  13. Investigation of the structure and properties of titanium-stainless steel permanent joints obtained by laser welding with the use of intermediate inserts and nanopowders

    NASA Astrophysics Data System (ADS)

    Cherepanov, A. N.; Orishich, A. M.; Pugacheva, N. B.; Shapeev, V. P.

    2015-03-01

    Results of an experimental study of the structure, the phase composition, and the mechanical properties of laser-welded joints of 3-mm thick titanium and 12Kh18N10T steel sheets obtained with the use of intermediate inserts and nanopowdered modifying additives are reported. It is shown that that such parameters as the speed of welding, the radiation power, and the laser-beam focal spot position all exert a substantial influence on the welding-bath process and on the seam structure formed. In terms of chemical composition, most uniform seams with the best mechanical strength are formed at a 1-m/min traverse speed of laser and 2.35-kW laser power, with the focus having been positioned at the lower surface of the sheets. Under all other conditions being identical, uplift of the focus to workpiece surface or to a higher position results in unsteady steel melting, in a decreased depth and reduced degree of the diffusion-induced mixing of elements, and in an interpolate connection formed according to the soldering mechanism in the root portion of the seam. The seam material is an over-saturated copper-based solid solution of alloying elements with homogeneously distributed intermetallic disperse particles (Ti(Fe, Cr)2 and TiCu3) contained in this alloy. Brittle fracture areas exhibiting cleavage and quasi-cleavage facets correspond to coarse Ti(Fe, Cr)2 intermetallic particles or to diffusion zones primarily occurring at the interface with the titanium alloy. The reported data and the conclusions drawn from the numerical calculations of the thermophysical processes of welding of 3-mm thick titanium and steel sheets through an intermediate copper insert are in qualitative agreement with the experimental data. The latter agreement points to adequacy of the numerical description of the melting processes of contacting materials versus welding conditions and focal-spot position in the system.

  14. Effects of silica-coating on surface topography and bond strength of porcelain fused to CAD/CAM pure titanium.

    PubMed

    Fukuyama, Takushi; Hamano, Naho; Ino, Satoshi

    2016-01-01

    The aim of this study was to evaluate the shear bond strength of porcelain fusing to titanium and the effects of surface treatment on surface structure of titanium. In the shear bond strength test, titanium surface treatments were: conventional, silica-coating without bonding agent, and silica-coating with bonding agent. Titanium surface treatments for analysis by the atomic force microscope (AFM) were: polishing, alumina sandblasting and silica-coating. The shear bond strength value of silica-coating with bonding agent group showed significantly higher than that of other groups. In AFM observation results, regular foamy structure which is effective for wetting was only observed in silica-coating. Therefore, this structure might indicate silicon. Silica-coating renders forms a nanoscopic regular foamy structure, involved in superhydrophilicity, to titanium surface, which is markedly different from the irregular surface generated by alumina sandblasting. PMID:27041024

  15. Effects of the laser beam superficial heat treatment on the gas Tungsten arc Ti-6al-4v welded metal microstructure

    NASA Astrophysics Data System (ADS)

    Voiculescu, I.; Dontu, Octavian; Geanta, V.; Ganatsios, S.

    2008-03-01

    The microstructure of the weld and the extent to which it is different from the thermo-mechanically processed base material is strongly influenced by the thermal cycle of welding. The mechanical properties of composite weld structures in titanium alloys depend on structural characteristics of each region (weld, base material and heat affected area), influenced by the specific thermal cycle imposed during welding and the subsequent post-weld heat treatment. In order to improve the as-welded metal toughness and ductility, the welded metal was subjected to various post weld laser heat treatments, above and below beta transus temperature in a shielding atmosphere of pure argon. Standard micro-hardness measurements and tensile strength techniques showed higher mechanical properties of the heat treated samples in different conditions with respect to the base metal. Metallographic investigations attribute this to the formation of α'phases in heat treated material, especially in the weld metal.

  16. 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.…

  17. 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…

  18. 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. PMID:23177772

  19. 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.

  20. 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.

  1. 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.

  2. 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. PMID:23807314

  3. 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.

  4. 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.

  5. 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.

  6. 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. PMID:23274794

  7. Warm forming simulation of titanium tailor-welded blanks with experimental verification

    SciTech Connect

    Lai, C. P.; Chan, L. C.; Chow, C. L.

    2007-05-17

    The simulation of the forming process of Ti-TWBs at elevated temperatures using finite element analysis to determine the optimum forming conditions of Ti-TWBs is presented in this paper. For verification of the simulation results, titanium alloy (Ti-6Al-4V) was selected for the first instance to prepare the specimen of Ti-TWBs. The thickness combinations of 0.7mm/1.0mm and in widths of 20mm, 90mm and 110mm were used. A specific tooling system with temperature control device was developed to the forming of Ti-TWBs at 550 deg. C. A cylindrical punch of 50mm diameter was designed and manufactured. Different forming parameters (i.e. traveling distance of the punch and the stroke as well as the time of each forming process) and material characteristics under various temperatures were measured. In addition, the true stress and strain values by tensile test as well as the major and minor strain distributions of forming Ti-TWBs at elevated temperatures by Swift Forming test were carried out and applied as input into the finite element program. The simulation results indentify failure locations and Limit Dome Height (LDH) of Ti-TWBs at elevated temperatures and were compared with the measured ones. Finally, the optimum forming conditions of Ti-TWBs were determined based on the experimentally verified simulation results.

  8. Evidence for a transition in deformation mechanism in nanocrystalline pure titanium processed by high-pressure torsion

    NASA Astrophysics Data System (ADS)

    Yang, Chao; Song, Min; Liu, Yong; Ni, Song; Sabbaghianrad, Shima; Langdon, Terence G.

    2016-06-01

    Nanocrystalline titanium with an average grain size of about 60-70 nm was prepared by high-pressure torsion. The results of hardness and structural evolutions indicate that a strain-induced hardening-softening-hardening-softening behaviour occurs. For coarse-grained titanium, -type dislocation multiplication, twinning and a high pressure-induced α-to-ω phase transformation play major roles to accommodate deformation, leading to a significant strain hardening. As deformation proceeds, dynamic recrystallisation leads to a decrease in dislocation density, especially for -type dislocations, leading to a slight strain softening. The -component dislocation multiplication dominates the deformation when the grain size decreases to 100 nm and -component dislocation multiplication, grain refinement and the α-to-ω phase transformation contribute to the second strain hardening. The following strain softening is attributed to dynamic recovery.

  9. Effect of heat treatment on H2O2/HCl etched pure titanium dental implant: An in vitro study

    PubMed Central

    Zhang, Feng; Zhang, Chun-Fei; Yin, Mei-nv; Ren, Ling-Fei; Lin, Hai-sheng; Shi, Geng-sheng

    2012-01-01

    Summary Background Surface chemistry of dental implant plays an important role in osseointegration. Heat treatment might alter surface chemistry and result in different biological response. The aim of this study was to investigate the roles of heat treatment of H2O2/HCl-treated Ti implants in cell attachment, proliferation and osteoblastic differentiation. Material/Methods Sandblasted, dual acid-etched and H2O2/HCl heat-treated discs were set as the control group and sandblasted, dual acid-etched H2O2/HCl-treated discs were the test group. Both groups’ discs were sent for surface characterization. MC3T3-E1 cells were seeded on these 2 groups’ discs for 3 hours to 14 days, and then cell attachment, cell proliferation and cell differentiation were evaluated. Results Scanning electron microscope analysis revealed that the titanium discs in the 2 groups shared the same surface topography, while x-ray diffraction examination showed an anatase layer in the control group and titanium hydride diffractions in the test group. The cell attachment of the test group was equivalent to that of the control group. Cell proliferation was slightly stimulated at all time points in the control group, but the alkaline phosphatase (ALP) activity and osteocalcin (OC) production increased significantly in the test group compared with those in the control group at every time point investigated (p<0.05 or p<0.01). Moreover, the osteoblastic differentiation-related genes AKP-2, osteopontin (OPN) and OC were greatly up-regulated in the test group (p<0.05 or p<0.01). Conclusions The results implied that surface chemistry played an important role in cell response, and H2O2/HCl etched titanium surface without subsequent heat treatment might improve osseointegration response. PMID:22739726

  10. 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.

  11. 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.

  12. 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.

  13. Mechanical properties of titanium connectors.

    PubMed

    Neo, T K; Chai, J; Gilbert, J L; Wozniak, W T; Engelman, M J

    1996-01-01

    The tensile mechanical properties of welded titanium joints were studied, and intact titanium was used as controls. Welded joints were fabricated with either a stereographic laser-welding technique or a gas tungsten arc welding technique. The effect of heat treatment following a simulated porcelain application was also investigated. Heat-treated laser welds had significantly lower ultimate tensile strengths. Heat treatment had no effect on the modulus of elasticity or elongation, but generally significantly decreased the yield strength of the titanium specimens. The gas tungsten are welding specimens had significantly higher yield strengths and elastic moduli than the other two groups. The elongation of the control specimens was significantly greater than the elongation of the gas tungsten arc welding specimens, which was in turn significantly higher than that of the laser-welded specimens. PMID:8957877

  14. 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

  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. 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. PMID:27585912

  17. 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.

  18. 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.

  19. Effect of bulk microstructure of commercially pure titanium on surface characteristics and fatigue properties after surface modification by sand blasting and acid-etching.

    PubMed

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

    2016-04-01

    Surface modification techniques are widely used to enhance the biological response to the implant materials. These techniques generally create a roughened surface, effectively increasing the surface area thus promoting cell adhesion. However, a negative side effect is a higher susceptibility of a roughened surface to failure due to the presence of multiple stress concentrators. The purpose of the study reported here was to examine the effects of surface modification by sand blasting and acid-etching (SLA) on the microstructure and fatigue performance of coarse-grained and ultrafine-grained (UFG) commercially pure titanium. Finer grain sizes, produced by equal channel angular pressing, resulted in lower values of surface roughness in SLA-processed material. This effect was associated with greater resistance of the UFG structure to plastic deformation. The fatigue properties of UFG Ti were found to be superior to those of coarse-grained Ti and conventional Ti-6Al-4V, both before and after SLA-treatment. PMID:26703365

  20. Effect of nonthermal plasma treatment on surface chemistry of commercially-pure titanium and shear bond strength to autopolymerizing acrylic resin.

    PubMed

    Vechiato-Filho, Aljomar José; da Silva Vieira Marques, Isabella; dos Santos, Daniela Micheline; Matos, Adaias Oliveira; Rangel, Elidiane Cipriano; da Cruz, Nilson Cristino; Barão, Valentim Adelino Ricardo

    2016-03-01

    The effect of nonthermal plasma on the surface characteristics of commercially pure titanium (cp-Ti), and on the shear bond strength between an autopolymerizing acrylic resin and cp-Ti was investigated. A total of 96 discs of cp-Ti were distributed into four groups (n=24): Po (no surface treatment), SB (sandblasting), Po+NTP and SB+NTP (methane plasma). Surface characterization was performed through surface energy, surface roughness, scanning microscopy, energy dispersive spectroscopy, and X-ray diffraction tests. Shear bond strength test was conducted immediately and after thermocycling. Surface treatment affected the surface energy and roughness of cp-Ti discs (P<.001). SEM-EDS showed the presence of the carbide thin film. XRD spectra revealed no crystalline phase changes. The SB+NTP group showed the highest bond strength values (6.76±0.70 MPa). Thermocycling reduced the bond strength of the acrylic resin/cp-Ti interface (P<.05), except for Po group. NTP is an effective treatment option for improving the shear bond strength between both materials. PMID:26706504

  1. 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.

  2. In vitro infrared thermography assessment of temperature peaks during the intra-oral welding of titanium abutments

    NASA Astrophysics Data System (ADS)

    Degidi, Marco; Nardi, Diego; Sighinolfi, Gianluca; Merla, Arcangelo; Piattelli, Adriano

    2012-07-01

    Control of heat dissipation and transmission to the peri-implant area during intra-oral welding is very important to limit potential damage to the surrounding tissue. The aim of this in vitro study was to assess, by means of thermal infrared imaging, the tissue temperature peaks associated with the thermal propagation pathway through the implants, the abutments and the walls of the slot of the scaffold, generated during the welding process, in three different implant systems. An in vitro polyurethane mandible model was prepared with a 7.0 mm v-shape slot. Effects on the maximum temperature by a single welding procedure were studied using different power supplies and abutments. A total of 36 welding procedures were tested on three different implant systems. The lowest peak temperature along the walls of the 7.0 mm v-shaped groove (31.6 ± 2 °C) was assessed in the specimens irrigated with sterile saline solution. The highest peak temperature (42.8 ± 2 °C) was assessed in the samples with a contemporaneous power overflow and premature pincers removal. The results of our study suggest that the procedures used until now appear to be effective to avoid thermal bone injuries. The peak tissue temperature of the in vitro model did not surpass the threshold limits above which tissue injury could occur.

  3. 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.

  4. 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

  5. AB054. An improved technique for bladder cancer: pure laparoscopic radical cystectomy with orthotopic U-shape ileal neobladder using titanium staples

    PubMed Central

    Wang, Shuai; Qi, Xiaolong; Liu, Feng; Zheng, Min; Zhang, Dahong

    2015-01-01

    Objective To report our experience with an improved technique of laparoscopic radical cystectomy (LRC) and orthotopic ileal neobladder reconstruction, evaluating the perioperative and pathological outcomes. Methods We retrospectively reviewed the data of 56 cases who underwent radical cystoprostatectomy followed by construction of an orthotopic U-shaped ileal neobladder between August 2010 and December 2014. These data include intraoperative data, early and long-term postoperative complications, neobladder function, urinary continence and oncologic results. Also the key innovative procedure was introduced with details. Results The median time of the overall procedure was 212 min. The median estimated blood loss was 171 mL. The median hospitalization time after the operation was 21 days. Complications included two cases of unilateral ureter-pouch anastomotic strictures, one case of bilateral ureteral stricture, three cases of vesicourethral anastomotic strictures and three cases of vesicourethral leakage. The mean maximum pouch capacity was 446±32 mL, and pouch pressure at capacity was 18.1±2.6 cmH2O. The Qmax was 14±1.2 mL/s, and the mean post-void residual was 25±10 mL. There were nine cases of night-time incontinence at 3 months post-operatively. Negative surgical margins of the bladder specimens were achieved in all patients. During a follow-up period of 3 to 44 months (average 32.6 months), local recurrence was found in two patients and distant metastasis was occurred in another three patients. Conclusions Our preliminary experience showed that pure LRC with non-absorbable titanium staples assisted orthotopic U-shape ileal neobladder reconstruction is feasible based on perioperative data and oncologic features.

  6. 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.

  7. Experimental characterization and macro-modeling of mechanical strength of multi-sheets and multi-materials spot welds under pure and mixed modes I and II

    NASA Astrophysics Data System (ADS)

    Chtourou, Rim; Haugou, Gregory; Leconte, Nicolas; Zouari, Bassem; Chaari, Fahmi; Markiewicz, Eric

    2015-09-01

    Resistance Spot Welding (RSW) of multiple sheets with multiple materials are increasingly realized in the automotive industry. The mechanical strength of such new generation of spot welded assemblies is not that much dealt with. This is true in particular for experiments dedicated to investigate the mechanical strength of spot weld made by multi sheets of different grades, and their macro modeling in structural computations. Indeed, the most published studies are limited to two sheet assemblies. Therefore, in the first part of this work an advanced experimental set-up with a reduced mass is proposed to characterize the quasi-static and dynamic mechanical behavior and rupture of spot weld made by several sheets of different grades. The proposed device is based on Arcan test, the plates contribution in the global response is, thus, reduced. Loading modes I/II are, therefore, combined and well controlled. In the second part a simplified spot weld connector element (macroscopic modeling) is proposed to describe the nonlinear response and rupture of this new generation of spot welded assemblies. The weld connector model involves several parameters to be set. The remaining parameters are finally identified through a reverse engineering approach using mechanical responses of experimental tests presented in the first part of this work.

  8. 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.

  9. 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. PMID:22400276

  10. 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.

  11. Technique development for field inspection of cracking in seam welded ducts

    NASA Astrophysics Data System (ADS)

    Shell, Eric B.; Liljestrom, Greg C.; Benson, Craig; Shanahan, Stephen

    2014-02-01

    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.

  12. 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.

  13. 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.

  14. Will nonaerospace applications for titanium ever grow?

    NASA Astrophysics Data System (ADS)

    Katrak, Firoze E.; Servi, I. S.; Agarwal, J. C.

    1991-07-01

    Confronted with the currently attractive aerospace markets, titanium producers could choose to minimize their promotional effort in the nonaerospace sector. In such a case, primary producers would continue to give some support to a few nonaerospace market segments but would minimize product and market development in most other areas. Such a modus operandi is quite likely, in which case the 1990s may turn out to be as disappointing for the industrial application of titanium as were the 1980s. Such a trend is not desirable for titanium producers for two reasons: the military aerospace market is likely to shrink in the future,8 and the titanium content of commercial jet engines will decline.9 Thus, titanium producers need to adopt a strategy to increase nonaerospace applications. Such a strategy must accomplish at least the following: • Commit to reducing titanium mill product costs. • Convince potential users that titanium (sponge and) mill products will be available at a sustained cost much below the current cost. No radically new technologies are necessaryzzto meet the target sponge costs (i.e., the current processes can meet cost targets with plant and practice changes). • Begin developing new alloys specifically tailored to nonaerospace applications and lower-cost mill products. If and when new alloys become available, the potential growth in nonaerospace uses would be greater than the 1-10-100 rule, which applies to existing commercially pure titanium. • Work toward reducing value-added component costs by achieving cost reductions in secondary fabrication for selected niche applications. • Offer application engineering and technical support services, including the establishment of training centers (e.g., for field welding). • Develop estimates of cost effectiveness in target applications that will convince the users. If a strategy incorporating these elements is not adopted by titanium producers because of the short-term strength of aerospace demand

  15. 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.

  16. 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.

  17. Adhesive-Bonded Tab Attaches Thermocouples to Titanium

    NASA Technical Reports Server (NTRS)

    Cook, C. F.

    1982-01-01

    Mechanical strength of titanium-alloy structures that support thermocouples is preserved by first spotwelding thermocouples to titanium tabs and then attaching tabs to titanium with a thermosetting adhesive. In contrast to spot welding, a technique previously used for thermocouples, fatigue strength of the titanium is unaffected by adhesive bonding. Technique is also gentler than soldering or attaching thermocouples with a tap screw.

  18. 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). PMID:23852924

  19. 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.

  20. 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

  1. 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

  2. Preventing Contamination In Electron-Beam Welds

    NASA Technical Reports Server (NTRS)

    Goodin, Wesley D.; Gulbrandsen, Kevin A.; Oleksiak, Carl

    1990-01-01

    Simple expedient eliminates time-consuming, expensive manual hand grinding. Use of groove and backup tube greatly reduces postweld cleanup in some electron-beam welding operations. Tube-backup method developed for titanium parts, configurations of which prevents use of solid-block backup. In new welding configuration, tube inserted in groove to prevent contact between alumina beads and molten weld root. When welding complete and beads and tube removed, only minor spatter remains and is ground away easily.

  3. Synchrotron-Based Experimental Investigations and Numerical Modeling of the Kinetics of Phase Transformations in the Heat Affected Zone of Welds

    SciTech Connect

    2000-05-04

    Spatially Resolved X-Ray Diffraction (SRXRD) and Time Resolved X-Ray Diffraction (TRXRD) methods are being developed at LLNL for in-situ investigations of phase transformations in the heat-affected zone (HAZ) of welds. In this region of the weld, severe temperature gradients, high peak temperatures and rapid thermal fluctuations occur as the heat source passes through the material. These non-isothermal temperature fluctuations produce HAZ microstructures that cannot be predicted by conventional methods. The unique synchrotron-based experiments being developed here will enable the determination of phase transformation kinetics under true non-isothermal welding conditions, and can be used to aid in the development of models to predict HAZ microstructural evolution under a wide range of welding conditions. Commercially pure titanium, stainless steel alloys and plain carbon steels are currently under investigation.

  4. Cytotoxic effects of four types of welding fumes on macrophages in vitro: a comparative study.

    PubMed

    Pasanen, J T; Gustafsson, T E; Kalliomäki, P L; Tossavainen, A; Järvisalo, 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. PMID:3701879

  5. Development of the weldbond process for joining titanium

    NASA Technical Reports Server (NTRS)

    Fields, D.

    1972-01-01

    High quality resistance spot welds were produced by welding through epoxy adhesive on titanium alloys. Weldbond joints were consistently stronger than those of either mechanical fasteners, structural adhesive bonds, or mechanical fasteners with adhesive at the joint interface. Weldbond joints and/or spot weld joints showed superior strength at all temperature ranges as compared to other joints tested.

  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. Comparison of the deformation behaviour of commercially pure titanium and Ti-5Al-2.5Sn(wt.%) at 296 and 728 K

    NASA Astrophysics Data System (ADS)

    Li, H.; Mason, D. E.; Yang, Y.; Bieler, T. R.; Crimp, M. A.; Boehlert, C. J.

    2013-07-01

    The tension and tensile-creep deformation behaviours of a fully-α phase commercially pure (CP) Ti and a near-α Ti-5Al-2.5Sn(wt.%) alloy deformed in situ inside a scanning electron microscope were compared. Tensile tests were performed at 296 and 728 K, while tensile-creep tests were performed at 728 K. The yield stress of CP Ti decreased dramatically with increasing temperature. In contrast, temperature had much smaller effect on the yield stress of Ti-5Al-2.5Sn(wt.%). Electron backscattered diffraction was performed both before and after the deformation, and slip trace analysis was used to determine the active slip and twinning systems, as well as the associated global stress state Schmid factors. In tension tests of CP Ti, prismatic slip was the most likely slip system to be activated when the Schmid factor exceeded 0.4. Prismatic slip was observed over the largest Schmid factor range, indicating that the local stress tensor varies significantly from the global stress state of uniaxial tension. The basal slip activity in Ti-5Al-2.5Sn(wt.%) was observed in a larger faction of grains than in CP Ti. Pyramidal ⟨c + a⟩ slip was more prevalent in CP Ti. Although twinning was an active deformation mode in tension tests of the CP Ti, it was rare in Ti-5Al-2.5Sn(wt.%). During creep, dislocation slip was the primary apparent deformation mechanism in CP Ti, while evidence for dislocation slip was much less apparent in Ti-5Al-2.5Sn(wt.%), where grain boundary sliding was dominant. A robust statistical analysis was carried out to assess the significance of the comparative activity of the different slip systems under the variety of experimental conditions examined.

  8. Welding superalloy sheet for superconducting cable jackets

    SciTech Connect

    Summers, L.T.; Strum, M.J.; Morris, J.W. Jr.

    1983-08-01

    Autogenous gas tungsten arc welds produced in A-286 exhibit significantly lower yield and ultimate tensile strengths than comparably heat-treated base metal. Deformation in the aged weld metal is highly localized and delineates the dendritic microstructure. The observed mechanical properties are caused by the formation of precipitate-free regions located at the dendrite cores. These regions form as the result of titanium segregation during weld pool solidification which yields dendrite cores sufficiently lean in titanium as to prevent nucleation of the hardening phase.

  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. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.…

  15. 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…

  16. 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.

  17. Effect of tool geometry on ultrasonic welding process

    NASA Astrophysics Data System (ADS)

    Sasaki, Tomohiro; Sakata, Yutaro; Watanabe, Takehiko

    2014-08-01

    Ultrasonic welding of pure aluminum sheets is performed using two weld tools, one with a knurled surface and one with a cylindrical surface. Relative motion behaviors of each weld tool, with respect to the working materials, during ultrasonic welding tests are analyzed using the digital correlation method. Weld microstructure development is investigated on the basis of transitional weld stages in the context of relative motion behaviors. The dominant relative motion is between the two work materials at the beginning of the weld but changes to be the motion between the weld tool and the work material it is in contact with as weld time increases. Thermo-mechanical effects of the relative motion of the weld tool and the work materials, on the development of weld microstructure, are discussed.

  18. Welding mechanics for advanced component safety assessment

    NASA Astrophysics Data System (ADS)

    Siegele, Dieter

    2011-06-01

    Numerical methods are nowadays a useful tool for the calculation of distortion and residual stresses as a result from the welding process. Modern finite element codes not only allow for calculation of deformations and stresses due to the welding process but also take into account the change of microstructure due to different heating and cooling rates. As an extension to the pure welding simulation, the field of welding mechanics combines the mechanics and the material behaviour from the welding process with the assessment of service behaviour of welded components. In the paper, new results of experimental and numerical work in the field of welding mechanics are described. Through examples from automotive, nuclear and pipe-line applications it is demonstrated that an equilibrated treatment and a close interaction of "process", "properties" and "defects" are necessary to come up with an advanced fitness-forservice assessment of welded components.

  19. Aluminum laser welding optimization

    NASA Astrophysics Data System (ADS)

    Chmelíčková, Hana; Halenka, Viktor; Lapšanská, Hana; Havelková, Martina

    2007-04-01

    Pulsed Nd:YAG laser with maximal power 150 W is used in our laboratory to cut, drill and weld metal and non-metal thin materials to thickness 2 mm. Welding is realized by fixed processing head or movable fiber one with beam diameter 0,6 mm in focus plane. Welding of stainless and low-carbon steel was tested before and results are publicized and used in practice. Now the goal of our experiment was optimization of process parameters for aluminum that has other physical properties than steels, lower density, higher heat conductivity and surface reflexivity. Pure alumina specimen 0,8 mm and Al-Mg-Si alloy 0,5 mm prepared for butt welds. Problem with surface layer of Al IIO 3 was overcome by sanding and chemical cleaning with grinding paste. Critical parameters for good weld shape are specimen position from beam focus plane, pulse length and energy, pulse frequency and the motion velocity that determines percentage of pulse overlap. Argon as protective gas was used with speed 6 liters per second. Thermal distribution in material can be modeled by numerical simulation. Software tool SYSWELD makes possible to fit laser as surface heat source, define weld geometry, and make meshing of specimen to finite elements and compute heat conduction during process. Color isotherms, vectors, mechanical deformations and others results can be study in post-processing.

  20. More About Cutting Tool For Shaving Weld Beads

    NASA Technical Reports Server (NTRS)

    Oelgoetz, Peter A.; Davis, William M.

    1996-01-01

    Report describes modification and testing of proposed tool discussed in "Cutting Tool For Shaving Weld Beads" (MFS-30056). Modified version of commercial pneumatically driven rotary cutting tool removes such hard metals as nickel alloys, titanium, and stainless steels.

  1. 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.

  2. 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.

  3. 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…

  4. 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.

  5. Molten welding slag enthalpies

    SciTech Connect

    Stukalo, V.A.; Neshchimenko, N.Ya.; Batalin, G.I.; Patselii, N.V.; Galinich, V.I.

    1988-05-01

    We measured enthalpies at 1740-19970 K for four multicomponent oxide liquids. The initial materials were special-purity metal oxides, chemically pure manganese oxalate, and calcium fluoride. High-temperature calorimetry has been applied to the enthalpies of slags used in automatic constructional-steel welding. The mean specific heats have been calculated from the temperature dependence of the enthalpies. The enthalpies increase with the basicity in these slags.

  6. Friction welding.

    NASA Technical Reports Server (NTRS)

    Moore, T. J.

    1972-01-01

    Results of an exploratory study of the structure and properties of friction welds in Udimet 700 (U-700) and TD-nickel (TD-Ni) bar materials, as well as dissimilar U-700/TD-Ni friction welds. Butt welds were prepared by friction welding 12.7-mm-diam U-700 bars and TD-Ni bars. Specimens for elevated temperature tensile and stress rupture testing were machined after a postweld heat treatment. Friction welding of U-700 shows great potential because the welds were found to be as strong as the parent metal in stress rupture and tensile tests at 760 and 980 C. In addition, the weld line was not detectable by metallographic examination after postheating. Friction welds in TD-Ni or between U-700 and TD-Ni were extremely weak at elevated temperatures. The TD-Ni friction welds could support only 9% as much stress as the base metal for 10-hour stress rupture life at 1090 C. The U-700/TD-Ni weld could sustain only 15% as much stress as the TD-Ni parent metal for a 10-hour stress rupture life at 930 C. Thus friction welding is not a suitable joining method for obtaining high-strength TD-Ni or U-700/TD-Ni weldments.

  7. FRACTURE MECHANICAL MEASUREMENTS WITH COMMERCIAL STAINLESS STEELS AT 4 K AND WITH CP-TITANIUM AT 173 K

    SciTech Connect

    Nyilas, A.; Mitterbacher, H.

    2010-04-08

    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 MPasq root(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.

  8. 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.

  9. Investigation of real-time microstructure evolution in steep thermal gradients using in-situ spatially resolved X-ray diffraction: A case study for Ti fusion welds

    SciTech Connect

    Ressler, T.; Wong, J.; Elmer, J.W. |

    1998-12-24

    A recently developed spatially resolved X-ray diffraction (SRXRD) technique utilizing intense synchrotron radiation has been refined to yield phase and microstructural information down to 200 {micro}m in spatial extent in materials subjected to steep thermal gradients during processing. This SRXRD technique has been applied to map completely the phases and their solid-state transformation in the so-called heat-affected zone (HAZ) in titanium fusion welds in situ during the welding process. Detailed profile analysis of the SRXRD patterns revealed four principal microstructural regions at temperature in the vicinity of the HAZ surrounding the liquid weld pool: (i) a completely transformed {beta}-Ti zone 2--3 mm adjacent to the liquid weld pool; (ii) a mixed {alpha} + {beta}-it region surrounding the pure {beta}-Ti zone, (iii) a back-transformed {alpha}-Ti zone on the backside of the HAZ where pure {beta}-Ti once existed at temperature well above the {alpha} {r_arrow} {beta} transformation isotherm, and (iv) a more diffused region outside the HAZ where annealing and recrystallization of the {alpha}-it base metal occur. The high-temperature microstructures so derived corroborate well the expected transformation kinetics in pure titanium, and the observed phase transformation boundaries are in good agreement with those predicted from the transformation isotherms calculated from a simplified heat-flow model. Based on a detailed assessment of the SRXRD setup employed, improved experimentations such as a smaller beam spot emitted from third generation synchrotron sources, better mechanical stability (tighter scattering geometry), and use of an area detector would enable more quantitative structural information for future phase dynamics studies exemplified by this work.

  10. 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.

  11. A study on the influence of ultrasonic processing on microstructure during laser welding phases

    NASA Astrophysics Data System (ADS)

    Liu, H. D.; Hu, F. Y.; Cui, A. Y.; Li, H. B.

    2015-12-01

    This paper proposes new welding technology that combines ultrasonic processing across different phases based on laser welding (UPPLW) and laser processing technology. The welding experiment used a 1.5 mm thick titanium alloy. The specimen was made metallographically prepared and the microstructural grain size of the welded joint was rated by metallurgical processing software, verifying that this new process can refine grains and improve joint properties.

  12. 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…

  13. 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)

  14. Cutting Tool For Shaving Weld Beads

    NASA Technical Reports Server (NTRS)

    Hoffman, David S.; Mcferrin, David C.; Daniel, Ronald L., Jr.; Coby, John B., Jr.; Dawson, Sidney G.

    1995-01-01

    Cutting tool proposed for use in shaving weld beads flush with adjacent surfaces of weldments. Modified version of commercial pneumatically driven rotary cutting tool, cutting wheel of which turns at speeds sufficient for machining nickel alloys, titanium, and stainless steels. Equipped with forward-mounted handle and rear-mounted skid plate to maximize control and reduce dependence on skill of technician.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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…

  1. 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…

  2. Welding II.

    ERIC Educational Resources Information Center

    Allegheny County Community Coll., Pittsburgh, PA.

    Instructional objectives and performance requirements are outlined in this course guide for Welding II, a performance-based course offered at the Community College of Allegheny County to introduce students to out-of-position shielded arc welding with emphasis on proper heats, electrode selection, and alternating/direct currents. After introductory…

  3. 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.

  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. 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

  6. The Effect of Yttrium on Ti-5111 Gas Tungsten Arc Welds

    NASA Astrophysics Data System (ADS)

    Neuberger, B. W.; Oberson, P. G.; Ankem, S.

    2011-05-01

    Much interest has developed in the near- α titanium alloy Ti-5Al-1Sn-1V-1Zr-0.8Mo (Ti-5111) for naval applications. When gas tungsten arc welded with filler metal that has the same chemical composition as the base metal, however, the weld FZ tends to be harder and less ductile than the base metal, which may make the weld susceptible to failure. This behavior may be attributed to the presence of oxygen impurities and the large prior- β grain size in the weld. In this investigation, the addition of a small amount of yttrium to the weld filler metal can decrease hardening and increase the ductility of Ti-5111 welds, which is beneficial for weld performance. Microstructural and chemical analyses of unmodified and yttrium-modified Ti-5111 welds are presented along with results from mechanical testing of the welds.

  7. Microstructural evolution under dual ion irradiation and in-reactor creep of type 316 stainless steel welded joints*1

    NASA Astrophysics Data System (ADS)

    Kohyama, A.; Kohno, Y.; Hishinuma, A.

    1994-09-01

    Electron beam (EB) welding was applied to 316SS and the titanium modified 316SS (JPCA). For the prospective improvement of swelling in welded joints, modified TIG or EB welding procedures utilizing titanium or nickel foil insertion were employed. For the case of EB welding of 15 mm thickness I-butt joint, the higher weld heat input showed better swelling resistance in the joints. The in-reactor creep results suggest that irradiation creep in welded joints may not be a big concern, as far as swelling resistance is maintained. So, Ni addition, stress relief treatment and high heat input for EB welding with optimization of welding condition are recommended for suppressing irradiation creep and swelling.

  8. 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

  9. 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.

  10. 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…

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Ribbon Reduces Spiking in Electron-Beam Welding

    NASA Technical Reports Server (NTRS)

    Olson, R. E.

    1984-01-01

    Spiking in electron-beam welding reduced by placing high-vapor-pressure substance along path of electron beam. Strip of metal having vapor pressure higher than base metal at same temperature placed in slot machined along weld line. Strip vaporizes as beam strikes it, and vapor pressure keeps surface tension from closing off top of channel. Technique used successfully on nickel alloys and aluminum alloys and effective on steel and titanium.

  16. 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

  17. 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.

  18. 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.

  19. 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. PMID:17620189

  20. 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.

  1. 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

  2. Fusion welding. (Latest citations from the EI Compendex*plus database). Published Search

    SciTech Connect

    Not Available

    1994-11-01

    The bibliography contains citations concerning the fusion welding of metals and non-metals. Among the materials cited are aluminum alloys, stainless steel, high density polyethylenes, titanium, ceramic fibers, and glass. Improvement of fusion welding through modeling and real-time control, studies on the bloating mechanism of shales, and prevention of fusion welding are also examined. (Contains a minimum of 53 citations and includes a subject term index and title list.)

  3. 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.

  4. Dependence of fracture toughness of molybdenum laser welds on processing parameters and in-situ oxygen gettering

    SciTech Connect

    Pope, L.E.; Jellison, J.L.

    1980-01-01

    Fracture toughness properties have been determined for laser welds in different grades of molybdenum. The fracture toughness of welds in sintered molybdenum was consistently less than the fracture toughness of welds in vacuum arc remelted molybdenum. These differences cannot be attributed to oxygen content, since the oxygen level was nominally the same for all grades of molybdenum examined in this program. Alloy additions of titanium by means of physically deposited coatings significantly improved the fracture toughness of welds in sintered molybdenum, whereas titanium additions to welds in vacuum arc remelted molybdenum decreased the fracture toughness slightly. Pulsed laser welds exhibited fine columnar structures and, in the case of sintered molybdenum, superior fracture toughness when compared with continuous wave laser welds. 6 figures, 3 tables.

  5. Surface characterizations of variously treated titanium materials.

    PubMed

    Lim, Y J; Oshida, Y; Andres, C J; Barco, M T

    2001-01-01

    The attachment of cells to titanium surfaces is an important phenomenon in the area of clinical implant dentistry. A major consideration in designing implants has been to produce surfaces that promote desirable responses in the cells and tissues. To achieve these requirements, the titanium implant surface can be modified in various ways. This research was designed to elucidate the relationship between surface roughness (Ra) and contact angle (theta) of various engineered titanium surfaces of commercially pure titanium, titanium-aluminum-vanadium alloy (Ti-6Al-4V), and titanium-nickel (TiNi) alloy. The contact angle was measured using distilled water, 1% sodium chloride solution, human neutrophils, and osteoblast-like cells. Surface oxide crystallography was identified by transmission electron diffraction. It was found that: (1) there were no significant differences in contact angles among the 4 media; (2) for commercially pure titanium, a combined treatment (hydrofluoric acid/nitric acid/water --> sodium hydroxide --> oxidation) showed the lowest theta (10.51 degrees in water), while the surface treated with sulfuric acid showed the highest value (72.99 degrees in water); (3) for all commercially pure titanium samples, when theta is greater than 45 degrees, the contact angle increases linearly with Ra (hydrophobic nature) and the surface is covered with rutile-type oxide only, while the contact angle decreases linearly with Ra when theta is less than 45 degrees (hydrophilic nature) and the surface is covered with a mixture of rutile and anatase oxides; and (4) a similar trend was found on Ti-6Al-4V and TiNi surfaces. PMID:11432653

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. The effects of gas nitriding on fatigue behavior in titanium and titanium alloys

    SciTech Connect

    Tokaji, K.; Ogawa, T.; Shibata, H.

    1999-04-01

    Fatigue behavior has been studied on gas-nitrided smooth specimens of commercial pure titanium, an alpha/beta Ti-6Al-4V alloy, and a beta Ti-15Mo-5Zr-3Al alloy under rotating bending, and the obtained results were compared with the fatigue behavior of annealed or untreated specimens. It was found that the role of the nitrided layer on fatigue behavior depended on the strength of the materials. Fatigue strength was increased by nitriding in pure titanium, while it was decreased in the Ti-6Al-4V and Ti-15Mo-5Zr-3Al alloys. Based on detailed observations of fatigue crack initiation, growth, and fracture surfaces, the improvement and the reduction in fatigue strength by nitriding in pure titanium and both alloys were primarily attributed to enhanced crack initiation resistance and to premature crack initiation of the nitrided layer, respectively.

  12. 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. PMID:17385227

  13. 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.

  14. 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.

  15. 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)

  16. 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.

  17. Twisted partially pure spinors

    NASA Astrophysics Data System (ADS)

    Herrera, Rafael; Tellez, Ivan

    2016-08-01

    Motivated by the relationship between orthogonal complex structures and pure spinors, we define twisted partially pure spinors in order to characterize spinorially subspaces of Euclidean space endowed with a complex structure.

  18. Fatigue behavior of titanium alloys

    SciTech Connect

    Boyer, R.R.; Eylon, D.; Luetjering, G.

    1999-07-01

    This symposium was international in nature, with leaders in the fields of fatigue technology and the metallurgy of titanium from the US, Europe and Asia. It covered basic research, development, applications and modeling--life predictions and design of both fatigue crack initiation and propagation of titanium alloys. There were presentations on the full range of titanium alloy systems, from commercially pure and {alpha}-alloys, {alpha}/{beta}- and {beta}-alloys to the gamma titanium aluminides. The effects of processing/heat treatment/microstructure on the fatigue properties were discussed, and models proposed to correlate the microstructures to the observed fatigue performance. Test environments reported on included hard vacuum (and the effect of vacuum level), vacuums with partial pressures of miscellaneous gases, lab air and aqueous media. A session was devoted to the effects of environment and fatigue enhancement via surface treatments using techniques such as shot peening and roller burnishing. The effects of dwell on both S-N and crack growth rate behavior were covered. It was a very comprehensive symposium with presentations from academia, government laboratories and industry, with industrial participants ranging from the petroleum industry to medical and aerospace interests. This book has been separated into four sections, representing the technology areas covered in various sessions, namely Mechanisms of Fatigue crack Initiation and Propagation of Conventional Alloys, Fatigue in Intermetallics, Environmental and Surface Aspects of Fatigue, and Application, Life Prediction and Design. Separate abstracts were prepared for most papers in this volume.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Surface Residual Stresses in Ti-6Al-4V Friction Stir Welds: Pre- and Post-Thermal Stress Relief

    NASA Astrophysics Data System (ADS)

    Edwards, P.; Ramulu, M.

    2015-09-01

    The purpose of this study was to determine the residual stresses present in titanium friction stir welds and if a post-weld thermal stress relief cycle would be effective in minimizing those weld-induced residual stresses. Surface residual stresses in titanium 6Al-4V alloy friction stir welds were measured in butt joint thicknesses ranging from 3 to 12 mm. The residual stress states were also evaluated after the welds were subjected to a post-weld thermal stress relief cycle of 760 °C for 45 min. High (300-400 MPa) tensile residual stresses were observed in the longitudinal direction prior to stress relief and compressive residual stresses were measured in the transverse direction. After stress relief, the residual stresses were decreased by an order of magnitude to negligible levels.

  4. 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.

  5. 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.

  6. 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.…

  7. 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. PMID:21030147

  8. 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.

  9. 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

  10. Optical Welding Torch

    NASA Technical Reports Server (NTRS)

    Richardson, R. W.

    1987-01-01

    Gas/tungsten-arc welding torch supports electrode at center while enabling viewing of weld area along torch axis. Gas torch accommodates lens and optical fibers, all part of vision system for welding robot. Welding torch includes spoked structure in central bore of optical body. Structure supports welding electrode, carries electric current to it, and takes heat away from it. Spokes formed by drilling six holes 60 degrees apart around center line of torch.

  11. 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.

  12. Opportunities in the electrowinning of molten titanium from titanium dioxide

    NASA Astrophysics Data System (ADS)

    van Vuuren, D. S.; Engelbrecht, A. D.; Hadley, T. D.

    2005-10-01

    The value chain of titanium products shows that the difference between the cost of titanium ingot and titanium dioxide is about 9/kg titanium. In contrast, the price of aluminum, which is produced in a similar way, is only about 1.7/kg. Electrowinning of molten titanium from titanium dioxide is therefore believed to have significant potential to reduce the cost of titanium products. The process is hampered by the high operating temperatures and sophisticated materials of construction required; the high affinity of titanium for carbon, oxygen, and nitrogen; and physical and chemical properties of the different titanium oxide species when reducing titanium from Ti4+ to metallic titanium.

  13. 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.

  14. Abrasion resistance of titanium nitride coatings formed on titanium by ion-beam-assisted deposition.

    PubMed

    Sawase, T; Yoshida, K; Taira, Y; Kamada, K; Atsuta, M; Baba, K

    2005-02-01

    To improve the physical properties of the pure titanium surface, thin titanium nitride (TiN) films were deposited by means of ion-beam-assisted deposition. Film structure was confirmed as TiN by X-ray diffraction analysis. Surface hardness and abrasion resistance were significantly improved on TiN-coated specimens. Five combinations of oral hygiene instruments and materials were applied to the specimens as simulations of the oral environment. Treatment with the metal scaler and ultrasonic scaler severely changed the surface features and significantly increased the surface roughness parameters on pure titanium controls, whereas only small scratches and dull undulations were seen on the TiN-coated specimens. Profilometric tracings and scanning electron micrographs demonstrated the improved abrasion resistance of the TiN-coated specimens. PMID:15641983

  15. Effect of humidity on fretting wear of several pure metals

    NASA Technical Reports Server (NTRS)

    Goto, H.; Buckley, D. H.

    1984-01-01

    Fretting wear experiments with several pure metals were conducted in air at various relative humidity levels. The materials used were iron, aluminum, copper, silver, chromium, titanium, and nickel. Each pure metal had a maximum fretting wear volume at a specific humidity level RH sub max that was not dependent on mechanical factors such as contact load, fretting amplitude, and frequency in the ranges studied. The weight loss due to fretting wear at RH sub max for each pure metal decreased with increasing heat of oxygen adsorption on the metal, indicating that adhesive wear dominated at RH sub max.

  16. 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.

  17. 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.

  18. 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. PMID:23338261

  19. 7 CFR 916.16 - Pure grower or pure producer.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Pure grower or pure producer. 916.16 Section 916.16... Order Regulating Handling Definitions § 916.16 Pure grower or pure producer. (a) Pure grower means any...); or (2) Who produces and handles his or her own product; Provided, That a pure grower can pack...

  20. 7 CFR 916.16 - Pure grower or pure producer.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Pure grower or pure producer. 916.16 Section 916.16... Order Regulating Handling Definitions § 916.16 Pure grower or pure producer. (a) Pure grower means any...); or (2) Who produces and handles his or her own product; Provided, That a pure grower can pack...

  1. 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.

  2. 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.

  3. 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.

  4. Electrochemical behavior of titanium in saline environments: The effects of temperature, pH, and microstructure

    SciTech Connect

    VanVliet, K.J.; Wang, Z.F.; Briant, C.L.; Kumar, K.S.

    1998-12-31

    This research investigates the effects of temperature, pH, degree of salinity, galvanic coupling, microstructure, and composition on the electrochemical behavior of commercially pure titanium in a saline environment. Essentially, the findings establish that increased temperature, altered microstructure, decreased pH, and decreased purity of titanium all serve to increase the corrosion potential and cathodic reaction rate, thus making the metal more susceptible to hydrogen absorption. Further, the data indicate that galvanic coupling with certain metals such as naval brass and stainless steel can anodically polarize titanium, whereas coupling with metals such as aluminum, HY80 steel, and zinc catholically polarizes titanium, thus promoting hydrogen evolution on the titanium surface.

  5. Titanium hermetic seals

    DOEpatents

    Brow, Richard K.; Watkins, Randall D.

    1995-07-04

    Titanium is prenitrided by being heated in a nitrogen environment under conditions which give rise to the formation of a titanium-nitride surface layer on the titanium. Titanium thus prenitrided may be used in electrical components which are hermetically sealed using silicate glasses and standard glass sealing techniques. According to the method of the invention, alkali volatilization and formation of deleterious interfacial silicide are inhibited.

  6. Titanium hermetic seals

    DOEpatents

    Brow, Richard K.; Watkins, Randall D.

    1995-01-01

    Titanium is prenitrided by being heated in a nitrogen environment under conditions which give rise to the formation of a titanium-nitride surface layer on the titanium. Titanium thus prenitrided may be used in electrical components which are hermetically sealed using silicate glasses and standard glass sealing techniques. According to the method of the invention, alkali volatilization and formation of deleterious interfacial silicide are inhibited.

  7. Sealing glasses for titanium and titanium alloys

    DOEpatents

    Brow, R.K.; Watkins, R.D.

    1988-01-21

    Glass compositions containing CaO, Al/sub 2/O/sub 3/, B/sub 2/O/sub 3/, SrO and BaO of various combinations of mole % are provided. These compositions are capable of forming stable glass-to-metal seals with titanium and titanium alloys, for use in components such as seals for battery headers.

  8. Sealing glasses for titanium and titanium alloys

    DOEpatents

    Brow, Richard K.; Watkins, Randall D.

    1992-01-01

    Glass compositions containing CaO, Al.sub.2 O.sub.3, B.sub.2 O.sub.3, SrO and BaO of various combinations of mole % are provided. These compositions are capable of forming stable glass-to-metal seals with titanium and titanium alloys, for use in components such as seals for battery headers.

  9. Purely lytic osteosarcoma

    SciTech Connect

    De Santos, L.A.; Eideken, B.

    1982-11-01

    The radiographic features of 42 purely lytic osteosarcomas are presented. Purely lytic osteosarcoma is identified as a lytic lesion of bone with no demonstrable osteoid matrix by conventional radiographic modalities. Purely lytic osteosarcoma represented 13.7% of a group of 305 osteosarcomas. The most common presentation was that of a lytic illdefined lesion with a moderate to large extraosseous mass component. Nine lesions presented with benign radiographic features. The differential diagnosis is outlined. The need for awareness of this type of presentation of osteosarcoma is stressed.

  10. 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.

  11. Effect of friction stir welding and post-weld heat treatment on a nanostructured ferritic alloy

    DOE PAGESBeta

    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 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

  12. 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.

  13. 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.

  14. 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. PMID:23903578

  15. Treatment of fractures of the condylar head with resorbable pins or titanium screws: an experimental study.

    PubMed

    Schneider, Matthias; Loukota, Richard; Kuchta, Anne; Stadlinger, Bernd; Jung, Roland; Speckl, Katrin; Schmiedekampf, Robert; Eckelt, Uwe

    2013-07-01

    We aimed to compare in vivo the stability of fixation of condylar fractures in sheep using sonic bone welding and standard titanium screws. We assessed stability of the osteosynthesis and maintenance of the height of the mandibular ramus. Height decreased slightly in both groups compared with the opposite side. The volume of the condyle increased considerably in both groups mainly because callus had formed. The results showed no significant disadvantages for pin fixation compared with osteosynthesis using titanium screws. PMID:22901526

  16. Science: Pure or Applied?

    ERIC Educational Resources Information Center

    Evans, Peter

    1980-01-01

    Through a description of some of the activities which take place in his science classroom, the author makes a strong case for the inclusion of technology, or applied science, rather than pure science in the primary curriculum. (KC)

  17. Pure-quartic solitons.

    PubMed

    Blanco-Redondo, Andrea; de Sterke, C Martijn; Martijn, de Sterke C; Sipe, J E; Krauss, Thomas F; Eggleton, Benjamin J; Husko, Chad

    2016-01-01

    Temporal optical solitons have been the subject of intense research due to their intriguing physics and applications in ultrafast optics and supercontinuum generation. Conventional bright optical solitons result from the interaction of anomalous group-velocity dispersion and self-phase modulation. Here we experimentally demonstrate a class of bright soliton arising purely from the interaction of negative fourth-order dispersion and self-phase modulation, which can occur even for normal group-velocity dispersion. We provide experimental and numerical evidence of shape-preserving propagation and flat temporal phase for the fundamental pure-quartic soliton and periodically modulated propagation for the higher-order pure-quartic solitons. We derive the approximate shape of the fundamental pure-quartic soliton and discover that is surprisingly Gaussian, exhibiting excellent agreement with our experimental observations. Our discovery, enabled by precise dispersion engineering, could find applications in communications, frequency combs and ultrafast lasers. PMID:26822758

  18. Pure-quartic solitons

    PubMed Central

    Blanco-Redondo, Andrea; Martijn, de Sterke C.; Sipe, J.E.; Krauss, Thomas F.; Eggleton, Benjamin J.; Husko, Chad

    2016-01-01

    Temporal optical solitons have been the subject of intense research due to their intriguing physics and applications in ultrafast optics and supercontinuum generation. Conventional bright optical solitons result from the interaction of anomalous group-velocity dispersion and self-phase modulation. Here we experimentally demonstrate a class of bright soliton arising purely from the interaction of negative fourth-order dispersion and self-phase modulation, which can occur even for normal group-velocity dispersion. We provide experimental and numerical evidence of shape-preserving propagation and flat temporal phase for the fundamental pure-quartic soliton and periodically modulated propagation for the higher-order pure-quartic solitons. We derive the approximate shape of the fundamental pure-quartic soliton and discover that is surprisingly Gaussian, exhibiting excellent agreement with our experimental observations. Our discovery, enabled by precise dispersion engineering, could find applications in communications, frequency combs and ultrafast lasers. PMID:26822758

  19. Pure-quartic solitons

    NASA Astrophysics Data System (ADS)

    Blanco-Redondo, Andrea; Martijn, De Sterke C.; Sipe, J. E.; Krauss, Thomas F.; Eggleton, Benjamin J.; Husko, Chad

    2016-01-01

    Temporal optical solitons have been the subject of intense research due to their intriguing physics and applications in ultrafast optics and supercontinuum generation. Conventional bright optical solitons result from the interaction of anomalous group-velocity dispersion and self-phase modulation. Here we experimentally demonstrate a class of bright soliton arising purely from the interaction of negative fourth-order dispersion and self-phase modulation, which can occur even for normal group-velocity dispersion. We provide experimental and numerical evidence of shape-preserving propagation and flat temporal phase for the fundamental pure-quartic soliton and periodically modulated propagation for the higher-order pure-quartic solitons. We derive the approximate shape of the fundamental pure-quartic soliton and discover that is surprisingly Gaussian, exhibiting excellent agreement with our experimental observations. Our discovery, enabled by precise dispersion engineering, could find applications in communications, frequency combs and ultrafast lasers.

  20. 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

  1. Effect of chemical polishing in titanium materials for low outgassing

    NASA Astrophysics Data System (ADS)

    Ishizawa, K.; Kurisu, H.; Yamamoto, S.; Nomura, T.; Murashige, N.

    2008-03-01

    A chemical polishing using a nitric acid solution was found to be the most suitable for the titanium materials. 1.8 nm of small surface roughness was observed in a microscopic range in 1 μm square, and 7 nm of a thin oxide layer was shown to exist for the chemically polished titanium. The surface processing for the titanium was developed combining the chemical polishing and the precision cleaning. The chemically polished pure titanium of JIS grade 2 showed extremely low outgassing rate below 10-12 Pams-1 after baking process, which is two orders of magnitude smaller than that for standard vacuum materials under the same baking condition. Outgassing rates of the titanium is about 1/5 of that for a stainless steel without baking process.

  2. Welding-Current Indicator

    NASA Technical Reports Server (NTRS)

    Hensley, Milton C.; Huston, Steven W.; Kroy, Ralph E.

    1990-01-01

    Light flashes on to indicate high current. Simple, inexpensive display circuit indicates when 3,000-A welding current flows in welding gun. Onset of welding current induces voltage and current in 1,000-turn, 28-gauge copper-wire coil. Single-transistor amplifier amplifies induced current, energizing light-emitting diode (LED) connected to collector of transistor. Light from LED gives simple, direct indication of welding current.

  3. 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.

  4. Geomorphology: Pure and applied

    SciTech Connect

    Hart, M.G.

    1986-01-01

    The book summarizes the history of intellectual debate in geomorphology and describes modern developments both ''pure'' and ''applied.'' The history begins well before W.M. Davis and follows through to such debates as those concerned with the Pleistocene. Modern developments in pure geomorphology are cast in terms of chapters on form, process, materials, and methods analysis. The applied chapters concentrate on environmental hazards and resources, and their management.

  5. 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.

  6. 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.

  7. 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…

  8. 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…

  9. 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.

  10. 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,…

  11. Diffusion welding tool

    NASA Technical Reports Server (NTRS)

    Milam, T. B.

    1973-01-01

    Tool allows flat plate diffusion welding to be done in standard brazing furnace. Weld is achieved using high water pressure applied by hand-operated positive-displacement pump. Good welds have been obtained between nickel and nickel-base alloy plates at temperature of 1200 K and water pressure of 13.8 million N/sq m.

  12. 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.

  13. 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

  14. Direct reduction processes for titanium oxide in molten salt

    NASA Astrophysics Data System (ADS)

    Suzuki, Ryosuke O.

    2007-02-01

    Molten salt electrolysis using CaCl2 is employed to produce pure titanium and its alloys directly from TiO2 and a mixture of elemental oxides, respectively, as an alternate to the Kroll process. This is because CaO, which is a reduction by-product, is highly soluble in CaCl2. Good-quality titanium containing only a small amount of residual oxygen has been successfully produced and scaled to industrial levels. Thermochemical and electrochemical bases are reviewed to optimize the process conditions. Several processes using molten salt are being examined for future progress in titanium processing.

  15. Monitoring of Laser Material Welding Process Using UV-Visible Spectrometer

    SciTech Connect

    Genc, B.; Kacar, E.; Akman, E.; Demir, A.

    2007-04-23

    UV-Visible spectrometer is used to record emission from magnesium and titanium metal plates during laser welding processing. Geometrically corrected Czerny-Turner configurations nearly eliminate defocusing problem. The Optikwerks software is used to find the optimum Czerny-Turner configuration and to choose optical elements such as grating types, mirrors focal length and diameter, and slit width. The design parameters of the uv-visible spectrometer in the wavelength range 200-1100 nm for monitoring laser material welding processing.

  16. 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.

  17. 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.

  18. A functionally graded titanium/hydroxyapatite film obtained by sputtering.

    PubMed

    Ozeki, Kazuhide; Yuhta, Toshio; Fukui, Yasuhiro; Aoki, Hideki; Nishimura, Ikuya

    2002-03-01

    A functionally graded film of titanium/hydroxyapatite (HA) was prepared on a titanium substrate using a radio frequency magnetron sputtering. The ratio of titanium to HA was controlled by moving the target shutter. The film was composed of five layers, with overall film thickness of 1 microm. The HA was concentrated close to the surface, while the titanium concentration increased with proximity to the substrate. The bonding strength between the film and the substrate was 15.2 MPa in a pull-out test and the critical load from a scratch test was 58.85 mN. The corresponding values of a pure HA sputtered film were 8.0 MPa and 38.47 mN, respectively. The bonding strength of a pure HA plasma spray coating was 10.4 MPa in the pull-out test. The graded film and the pure HA film were sputter-coated to a thickness of 1 microm on titanium columns (10 mm in length and 4 mm in diameter). These columns were implanted in diaphyses of the femora of six adult dogs and a push-out test was carried out after 2, 4, and 12 weeks. After 12 weeks, the push-out strengths of the graded film, the pure HA film and the non-coated columns were 3.7, 3.5, and 1.0 MPa. PMID:15348621

  19. Effects of superplastic deformation on the diffusion welding of SuperDux 65 stainless steel

    SciTech Connect

    Yeh, M.S.; Tseng, Y.H.; Chuang, T.H.

    1999-09-01

    The SuperDux 65 stainless steel diffusion welded in a nonsuperplastic state (880 C, 60 min) required greater pressure, compared to aluminum and titanium alloys, to create a contact area at the weld interface, which will increase the atomic diffusion paths. However, an unsatisfactory weld strength of 45.3 MPa was obtained under the applied pressure of 7 MPa. This alloy deformed easily at its superplastic temperature of 970 C, resulting in a tight contact surface. The higher welding temperature was also beneficial for atomic diffusion. Both effects were advantageous for diffusion welding, while the joined workpieces macroscopically deformed markedly. In this study, a two-stage diffusion welding method was proposed. The specimens were diffusion welded in a nonsuperplastic (or superplastic) state for a short time and then further diffusion welded at superplastic (or nonsuperplastic) temperatures for a longer heating period. It was found that the welding strength could be improved drastically using such a two-stage process. The contributions of superplastic deformation on the diffusion welding of this alloy during the two-stage process were clarified.

  20. 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.

  1. In situ observations of weld pool solidification using transparent metal-analog systems

    NASA Astrophysics Data System (ADS)

    Trivedi, R.; David, S. A.; Eshelman, M. A.; Vitek, J. M.; Babu, S. S.; Hong, T.; DebRoy, T.

    2003-04-01

    The dynamics of weld solidification were observed in situ using a laser welding process on transparent organic materials systems. Succinonitrile was used to simulate a pure metal system and succinonitrile with 1.2 wt. % acetone was used to simulate an alloy system. Observed weld pool shapes in succinonitrile were in good agreement with theoretical heat transfer calculations. The dynamics of weld pool shape in the succinonitrile-acetone system were related to complex interactions between grain orientation, grain selection, and dendrite orientations, which depend strongly on welding speed. An increase in welding speed leads to a transition from a steady-state to a nonsteady-state weld pool shape. Several other phenomena, including epitaxial growth, grain selection process, grain boundary melting, and porosity formation, were also observed.

  2. 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.

  3. Immediate loading of zygomatic implants using the intraoral welding technique: a 12-month case series.

    PubMed

    Degidi, Marco; Nardi, Diego; Piattelli, Adriano; Malevez, Chantal

    2012-10-01

    The aim of this prospective study was to evaluate the concept of intraoral welding as a suitable technique for fabricating a fixed restoration for the edentulous maxilla the day of surgery using standard and zygomatic implants. Ten consecutive patients (four men, six women; mean age, 62.3 ± 11.6 years) were involved in this study, each of whom had an edentulous atrophic maxilla and received two standard and two zygomatic implants. All implants were loaded immediately with a fixed prosthesis supported by an intraorally welded titanium framework. Definitive abutments were connected to the implants, and a titanium bar was welded to them using an intraoral welding unit. This framework was used to support the definitive prosthesis, which was fitted the day of implant placement. Patients were checked for swelling, pain, and framework stability at 1, 3, 6, and 12 months. A total of 20 immediately loaded standard and 20 zygomatic implants were used. The cases included in this study achieved a 100% prosthetic success rate at the 12-month follow-up. No fracture or radiographically detectable alteration of the welded frameworks was noticed. It is possible to successfully rehabilitate the edentulous atrophic maxilla with a permanently fixed prosthesis supported by an intraorally welded titanium framework attached to standard and zygomatic implants the day of surgery. PMID:22754908

  4. 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.

  5. Explosive welding of pipes

    NASA Astrophysics Data System (ADS)

    Drennov, O.; Burtseva, O.; Kitin, A.

    2006-08-01

    For connection by welding it is suggested to use the explosive welding method. This method is rather new. Nevertheless, it has become commonly used among the technological developments. This method can be advantageous (saving material and physical resources) comparing to its statical analogs (electron-beam welding, argon-arc welding, plasma welding, gas welding, etc.), in particular, in hard-to-reach areas due to their geographic and climatic conditions. The suggestion is to use water as filler. The principle of non-compressibility of liquid under quasi-dynamic loading is used. In one-dimensional gasdynamic and elastic-plastic calculations we determined non-deformed mass of water. Model experiments with pipes having radii R = 57 mm confirmed results of the calculations and the possibility in principle to weld pipes by explosion with use of water as filler.

  6. 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.

  7. 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.

  8. An investigation of the dynamic separation of spot welds under plane tensile pulses

    SciTech Connect

    Ma, Bohan; Fan, Chunlei; Chen, Danian Wang, Huanran; Zhou, Fenghua

    2014-08-07

    We performed ultra-high-speed tests for purely opening spot welds using plane tensile pulses. A gun system generated a parallel impact of a projectile plate onto a welded plate. Induced by the interactions of the release waves, the welded plate opened purely under the plane tensile pulses. We used the laser velocity interferometer system for any reflector to measure the velocity histories of the free surfaces of the free part and the spot weld of the welded plate. We then used a scanning electron microscope to investigate the recovered welded plates. We found that the interfacial failure mode was mainly a brittle fracture and the cracks propagated through the spot nugget, while the partial interfacial failure mode was a mixed fracture comprised ductile fracture and brittle fracture. We used the measured velocity histories to evaluate the tension stresses in the free part and the spot weld of the welded plate by applying the characteristic theory. We also discussed the different constitutive behaviors of the metals under plane shock loading and under uniaxial split Hopkinson pressure bar tests. We then compared the numerically simulated velocity histories of the free surfaces of the free part and the spot weld of the welded plate with the measured results. The numerical simulations made use of the fracture stress criteria, and then the computed fracture modes of the tests were compared with the recovered results.

  9. An investigation of the dynamic separation of spot welds under plane tensile pulses

    NASA Astrophysics Data System (ADS)

    Ma, Bohan; Fan, Chunlei; Chen, Danian; Wang, Huanran; Zhou, Fenghua

    2014-08-01

    We performed ultra-high-speed tests for purely opening spot welds using plane tensile pulses. A gun system generated a parallel impact of a projectile plate onto a welded plate. Induced by the interactions of the release waves, the welded plate opened purely under the plane tensile pulses. We used the laser velocity interferometer system for any reflector to measure the velocity histories of the free surfaces of the free part and the spot weld of the welded plate. We then used a scanning electron microscope to investigate the recovered welded plates. We found that the interfacial failure mode was mainly a brittle fracture and the cracks propagated through the spot nugget, while the partial interfacial failure mode was a mixed fracture comprised ductile fracture and brittle fracture. We used the measured velocity histories to evaluate the tension stresses in the free part and the spot weld of the welded plate by applying the characteristic theory. We also discussed the different constitutive behaviors of the metals under plane shock loading and under uniaxial split Hopkinson pressure bar tests. We then compared the numerically simulated velocity histories of the free surfaces of the free part and the spot weld of the welded plate with the measured results. The numerical simulations made use of the fracture stress criteria, and then the computed fracture modes of the tests were compared with the recovered results.

  10. 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.

  11. CO{sub 2} laser welding of duplex and super-duplex stainless steels (the effect of argon-nitrogen assist-gas mixtures)

    SciTech Connect

    Robinson, J.M.; Reed, R.C.; Camyab, A.

    1996-12-31

    Continuous wave CO{sub 2} laser welds have been fabricated on duplex and super duplex stainless steel substrates at a power of 3.5 kW. The work has examined the influence of Ar-N{sub 2} assist-gas mixtures on weld metal composition and microstructure. Welding in pure argon leads to reduction in the Cr, Ni, Mo and N content of the weld metal and a significant decrease in austenite volume fraction relative to the baseplate. Relative to welding in Ar, the use of a N{sub 2} bearing assist-gas restores the Cr, Ni and Mo levels to those found in the baseplate at the welding speeds employed. Moreover, the N{sub 2} bearing assist-gases result in an increase in the weld metal N content and austenite volume fraction relative to welding in pure Ar.

  12. Pure uterine lipoma.

    PubMed

    Erdem, Gulnur; Celik, Onder; Karakas, Hakki Muammer; Alkan, Alpay; Hascalik, Seyma

    2007-10-01

    Lipomatous tumors of the uterus are unusual, benign neoplasms seen in postmenopausal women. Although many of the mixed-type cases such as lipoleiomyoma and fibrolipoma have been reported, pure uterine lipomas are extremely rare. In the literature, a few cases with pure uterine lipoma have been reported. We first present the advanced magnetic resonance findings of pure uterine lipoma, followed by those of ultrasonography (US) and computed tomography (CT). We markedly detected lipid peaks on the magnetic resonance spectroscopy (MRS) and the apparent diffusion coefficient value to be 0.00 due to chemical-shift effects with diffusion-weighted imaging (DWI). Although pelvic lipomatous tumors can be diagnosed with US and CT, in some cases, further workup may be required to localize the lesion. MRI may yield more valuable data for differential diagnosis. MRS and DWI findings provide additional clues on the nature of the lesion. PMID:17905250

  13. Automated and aluminum welding technology

    NASA Astrophysics Data System (ADS)

    Jones, Clyde S.

    1994-10-01

    Automated welding technology and techniques for welding advanced aluminum alloys with potential for industrial and commercial applications have been developed by the National Aeronautics and Space Administration at the Marshall Space Flight Center. These technologies are being offered to private companies for commercial development, and include: Variable polarity plasma arc welding, a welding process that produces high-quality aluminum welds for fabrication of the space shuttle external tank and space station common module structures. This process uses reverse polarity pulses to produce welds virtually free of internal defects. Advanced weld sensor technology, comprised of machine vision-based weld seam tracking that uses both structured and global laser illumination for finding weld joints, even those difficult to discern by the human eye. Weld pool feedback is accomplished with a vision system to measure arc symmetry and molten weld pool geometry. A weld bead profiler trails the welding torch. It provides feedback to the process control system, which records quality control data.

  14. 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.

  15. Single crystals for welding research

    SciTech Connect

    David, S.A.; Boatner, L.A.

    1991-01-01

    Most welds last for many years, but a few fail after a relatively short time. Knowing the reasons why welds fail is important because cracks in welds can threaten the safety of people in buildings, airplanes, ships, automobiles, and power plants. Bad welds can lead to costly, extended shutdowns of industrial facilities such as petroleum refineries. Thus, research on this very important fabrication technology is critical to the multibillion-dollar welding industry. Research at ORNL and elsewhere strives to determine the structural features that make some welds strong and others weak. The goals are to find cost-effective ways to characterize the structure and strength of a new weld, correctly predict whether it will last a long time, and determine the welding conditions most likely to produce high-quality welds. There is more to welding than meets the eye. The cracks that make welds fail result from the complexities of microstructures formed during welding. Thus weld microstructure is linked to weld properties such as mechanical strength. As the hot weld material cools from a liquid into a solid, the crystalline grains grow at different speeds and in different directions, forming a new microstructure. By using single crystals rather than polycrystalline alloys to study different weld microstructures, scientists at ORNL have developed a way to predict more accurately the microstructures of various welds. The results could guide welders in providing the right conditions (correct welding speed, heat input, and weld thickness) for producing safer, higher-quality, and longer-lasting welds.

  16. Dual wire weld feed proportioner

    NASA Technical Reports Server (NTRS)

    Nugent, R. E.

    1968-01-01

    Dual feed mechanism enables proportioning of two different weld feed wires during automated TIG welding to produce a weld alloy deposit of the desired composition. The wires are fed into the weld simultaneously. The relative feed rates of the wires and the wire diameters determine the weld deposit composition.

  17. [Evaluation of exposure to fumes arising during welding of non-alloyed and low-alloyed steel by various methods].

    PubMed

    Matczak, W; Chmielnicka, J

    1988-01-01

    Evaluated in the paper is welders' exposure to fumes resulting from welding of nonalloyed and low-alloyed steel, whether pure or coated with protective layers, using two most popular welding techniques for those types of steel, i.e. metal active gas welding (MAG) and manual welding with covered electrode (MMA). Due to different chemical composition of fumes at particular workstations, the proper hygienic evaluation was based on measurements of individual concentrations of fumes in workers' breathing zone. A considerable contribution of the combined exposure was yielded by such fume constituents as manganese, ferrum and zinc (welding of steel coated with zinc protective layers), also chromium (welding of low- and -highalloyed steel), as well as copper (metal gas welding). The highest combined exposure (10-fold allowable value) was that of welders of steel coated with the zinc layer, using the metal active gas welding. PMID:3237059

  18. Titanium-niobium, a new finishing wire alloy.

    PubMed

    Dalstra, M; Denes, G; Melsen, B

    2000-02-01

    The mechanical properties of the newly introduced titanium-niobium finishing wires were investigated. Both in bending and torsional loading mode, the stiffness, yield point, post-yield behavior, and springback of titanium-niobium wires were experimentally determined and compared to those of equally sized stainless steel wires. The experimentally obtained values were also validated with theoretical values from engineering formulas of cantilever deformations. The ratios for these parameters for the two materials proved to be different in bending and torsion. The stiffness of titanium-niobium in bending is roughly half of that of stainless steel, whereas in torsion it is roughly one-third. These characteristics enable the clinician to use titanium-niobium for creative bends without the excessive force levels of steel wires. The springback of titanium-niobium in bending is 14% lower than that of steel, whereas in torsion it is about the same or even slightly higher than that of steel, thus making it possible to utilize the wire for even major third-order corrections. Finally, the weldability of titanium-niobium wires was found to be good, so it is possible to weld wires of different dimensions together for the generation of differentiated force systems. PMID:11168279

  19. Production of pure metals

    NASA Technical Reports Server (NTRS)

    Philipp, W. H.; Marsik, S. J.; May, C. E. (Inventor)

    1974-01-01

    A process for depositing elements by irradiating liquids is reported. Ultra pure elements are precipitated from aqueous solutions or suspensions of compounds. A solution of a salt of a metal to be prepared is irradiated, and the insoluble reaction product settles out. Some chemical compounds may also be prepared in this manner.

  20. Dahlbeck and Pure Ontology

    ERIC Educational Resources Information Center

    Mackenzie, Jim

    2016-01-01

    This article responds to Johan Dahlbeck's "Towards a pure ontology: Children's bodies and morality" ["Educational Philosophy and Theory," vol. 46 (1), 2014, pp. 8-23 (EJ1026561)]. His arguments from Nietzsche and Spinoza do not carry the weight he supposes, and the conclusions he draws from them about pedagogy would be…

  1. Laser Gas Nitriding of Titanium and Titanium Alloys

    NASA Astrophysics Data System (ADS)

    Dai, J. J.; Hou, S. Q.

    Titanium and titanium alloys are widely used in many fields due to some of their characteristics such as light density, high strength, and excellent corrosion resistance. However, poor mechanical performances limit their practical applications. Laser gas nitriding is a promising method used to improve the surface properties of components. Recent developments on laser gas nitriding of titanium and titanium alloys are reviewed. The processing parameters have important effects on the resulting characteristics of titanium and titanium alloys. The resulting microstructure and properties of laser gas nitrided specimens are presented. The problems to be solved and the prospects in the field of laser gas nitriding of titanium and titanium alloys are discussed.

  2. Dichloromethane photodegradation using titanium catalysts

    SciTech Connect

    Tanguay, J.F.; Suib, S.L.; Coughlin, R.W. )

    1989-06-01

    The use of titanium dioxide and titanium aluminosilicates in the photocatalytic destruction of chlorinated hydrocarbons is investigated. Titanium-exchanged clays, titanium-pillared clays, and titanium dioxide in the amorphous, anatase, and rutile forms are used to photocatalytically degrade dichloromethane to hydrochloric acid and carbon dioxide. Bentonite clays pillared by titanium dioxide are observed to be more catalytically active than titanium-exchanged clays. Clays pillared by titanium aluminum polymeric cations display about the same catalytic activity as that of titanium-exchanged clays. The rutile form of titanium dioxide is the most active catalyst studied for the dichloromethane degradation reaction. The anatase form of titanium dioxide supported on carbon felt was also used as a catalyst. This material is about five times more active than titanium dioxide-pillared clays. Degradation of dichloromethane using any of these catalysts can be enhanced by oxygen enrichment of the reaction solution or by preirradiating the catalyst with light.

  3. Welding arc plasma physics

    NASA Technical Reports Server (NTRS)

    Cain, Bruce L.

    1990-01-01

    The problems of weld quality control and weld process dependability continue to be relevant issues in modern metal welding technology. These become especially important for NASA missions which may require the assembly or repair of larger orbiting platforms using automatic welding techniques. To extend present welding technologies for such applications, NASA/MSFC's Materials and Processes Lab is developing physical models of the arc welding process with the goal of providing both a basis for improved design of weld control systems, and a better understanding of how arc welding variables influence final weld properties. The physics of the plasma arc discharge is reasonably well established in terms of transport processes occurring in the arc column itself, although recourse to sophisticated numerical treatments is normally required to obtain quantitative results. Unfortunately the rigor of these numerical computations often obscures the physics of the underlying model due to its inherent complexity. In contrast, this work has focused on a relatively simple physical model of the arc discharge to describe the gross features observed in welding arcs. Emphasis was placed of deriving analytic expressions for the voltage along the arc axis as a function of known or measurable arc parameters. The model retains the essential physics for a straight polarity, diffusion dominated free burning arc in argon, with major simplifications of collisionless sheaths and simple energy balances at the electrodes.

  4. Weld electrode cooling study

    NASA Astrophysics Data System (ADS)

    Masters, Robert C.; Simon, Daniel L.

    1999-03-01

    The U.S. auto/truck industry has been mandated by the Federal government to continuously improve their fleet average gas mileage, measured in miles per gallon. Several techniques are typically used to meet these mandates, one of which is to reduce the overall mass of cars and trucks. To help accomplish this goal, lighter weight sheet metal parts, with smaller weld flanges, have been designed and fabricated. This paper will examine the cooling characteristics of various water cooled weld electrodes and shanks used in resistance spot welding applications. The smaller weld flanges utilized in modern vehicle sheet metal fabrications have increased industry's interest in using one size of weld electrode (1/2 inch diameter) for certain spot welding operations. The welding community wants more data about the cooling characteristics of these 1/2 inch weld electrodes. To hep define the cooling characteristics, an infrared radiometer thermal vision system (TVS) was used to capture images (thermograms) of the heating and cooling cycles of several size combinations of weld electrodes under typical production conditions. Tests results will show why the open ended shanks are more suitable for cooling the weld electrode assembly then closed ended shanks.

  5. VPPA weld model evaluation

    NASA Technical Reports Server (NTRS)

    Mccutcheon, Kimble D.; Gordon, Stephen S.; Thompson, Paul A.

    1992-01-01

    NASA uses the Variable Polarity Plasma Arc Welding (VPPAW) process extensively for fabrication of Space Shuttle External Tanks. This welding process has been in use at NASA since the late 1970's but the physics of the process have never been satisfactorily modeled and understood. In an attempt to advance the level of understanding of VPPAW, Dr. Arthur C. Nunes, Jr., (NASA) has developed a mathematical model of the process. The work described in this report evaluated and used two versions (level-0 and level-1) of Dr. Nunes' model, and a model derived by the University of Alabama at Huntsville (UAH) from Dr. Nunes' level-1 model. Two series of VPPAW experiments were done, using over 400 different combinations of welding parameters. Observations were made of VPPAW process behavior as a function of specific welding parameter changes. Data from these weld experiments was used to evaluate and suggest improvements to Dr. Nunes' model. Experimental data and correlations with the model were used to develop a multi-variable control algorithm for use with a future VPPAW controller. This algorithm is designed to control weld widths (both on the crown and root of the weld) based upon the weld parameters, base metal properties, and real-time observation of the crown width. The algorithm exhibited accuracy comparable to that of the weld width measurements for both aluminum and mild steel welds.

  6. Use of the Plasma Spectrum RMS Signal for Arc-Welding Diagnostics.

    PubMed

    Mirapeix, Jesus; Cobo, Adolfo; Fuentes, Jose; Davila, Marta; Etayo, Juan Maria; Lopez-Higuera, Jose-Miguel

    2009-01-01

    A new spectroscopic parameter is used in this paper for on-line arc-welding quality monitoring. Plasma spectroscopy applied to welding diagnostics has typically relied on the estimation of the plasma electronic temperature, as there is a known correlation between this parameter and the quality of the seams. However, the practical use of this parameter gives rise to some uncertainties that could provoke ambiguous results. For an efficient on-line welding monitoring system, it is essential to prevent the appearance of false alarms, as well as to detect all the possible defects. In this regard, we propose the use of the root mean square signal of the welding plasma spectra, as this parameter will be proven to exhibit a good correlation with the quality of the resulting seams. Results corresponding to several arc-welding field tests performed on Inconel and titanium specimens will be discussed and compared to non-destructive evaluation techniques. PMID:22346696

  7. Effect of oxide inclusions on the solid state transformation in low-alloy steel fusion welds

    SciTech Connect

    Babu, S.S.; David, S.A.; Vitek, J.M.

    1995-12-31

    Non-metallic inclusions are known to influence the properties of low alloy steel weld metal by altering the microstructure development. Isothermal transformation kinetics of austenite to acicular ferrite and allotriomorphic ferrite were measured in reheated low alloy steel weld deposits with similar weld compositions and austenite grain size but different inclusion characteristics. Accelerated kinetics of the transformation to acicular ferrite were observed in the weld metal containing coarser titanium-rich inclusions. The results are also discussed in relation to the predictions of inclusion model. The kinetics of the transformation to allotriomorphic ferrite were not influenced by a change in the inclusion characteristics, but, rather, by a change in austenite grain size. A theoretical analysis of austenite grain development during weld cooling is considered in this work. The austenite grain size was found to depend on the driving force for transformation from 6 ferrite to austenite ({Delta}G{sup {sigma}->{gamma}}) calculated from ThermoCalc{trademark} software.

  8. Use of the Plasma Spectrum RMS Signal for Arc-Welding Diagnostics

    PubMed Central

    Mirapeix, Jesus; Cobo, Adolfo; Fuentes, Jose; Davila, Marta; Etayo, Juan Maria; Lopez-Higuera, Jose-Miguel

    2009-01-01

    A new spectroscopic parameter is used in this paper for on-line arc-welding quality monitoring. Plasma spectroscopy applied to welding diagnostics has typically relied on the estimation of the plasma electronic temperature, as there is a known correlation between this parameter and the quality of the seams. However, the practical use of this parameter gives rise to some uncertainties that could provoke ambiguous results. For an efficient on-line welding monitoring system, it is essential to prevent the appearance of false alarms, as well as to detect all the possible defects. In this regard, we propose the use of the root mean square signal of the welding plasma spectra, as this parameter will be proven to exhibit a good correlation with the quality of the resulting seams. Results corresponding to several arc-welding field tests performed on Inconel and titanium specimens will be discussed and compared to non-destructive evaluation techniques. PMID:22346696

  9. Microstructure evolution of electron beam welded Ti{sub 3}Al-Nb joint

    SciTech Connect

    Feng Jicai; Wu Huiqiang . E-mail: huiqiang_wu@hit.edu.cn; He Jingshan; Zhang Bingang

    2005-02-15

    The microstructure evolution characterization in high containing Nb, low Al titanium aluminide alloy of electron beam welded joints was investigated by means of OM, SEM, XRD, TEM and microhardness analysis. The results indicated that the microstructure of the weld metal made with electron beam under the welding conditions employed in this work was predominantly metastable, retaining ordered {beta} phase (namely B2 phase), and was independent of the welding parameters but independent of the size and the orientation of the weld solidification structures. As the heat input is decreased, the cellular structure zone is significantly reduced, and then the crystallizing morphology of fusion zone presented dendritically columnar structure. There existed grain growth coarsening in heat affected zone (HAZ) for insufficient polygonization. Both fusion zone (FZ) and the HAZ had higher microhardness than the base metal.

  10. Cleaning Internal-Weld Splatter

    NASA Technical Reports Server (NTRS)

    Snodgrass, R.

    1982-01-01

    Splattered metal produced by welding can be easily removed from inaccessible areas by method resembling ball milling. Hard steel balls are vibrated inside welded unit so that they "scrub away" excess metal on interior side of weld joint.

  11. Welding and joining: A compilation

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A compilation is presented of NASA-developed technology in welding and joining. Topics discussed include welding equipment, techniques in welding, general bonding, joining techniques, and clamps and holding fixtures.

  12. Computerized adaptive control weld skate with CCTV weld guidance project

    NASA Technical Reports Server (NTRS)

    Wall, W. A.

    1976-01-01

    This report summarizes progress of the automatic computerized weld skate development portion of the Computerized Weld Skate with Closed Circuit Television (CCTV) Arc Guidance Project. The main goal of the project is to develop an automatic welding skate demonstration model equipped with CCTV weld guidance. The three main goals of the overall project are to: (1) develop a demonstration model computerized weld skate system, (2) develop a demonstration model automatic CCTV guidance system, and (3) integrate the two systems into a demonstration model of computerized weld skate with CCTV weld guidance for welding contoured parts.

  13. EVALUATION OF CONSTANT CURRENT WELD CONTROL FOR PINCH WELDING

    SciTech Connect

    Korinko, P; STANLEY, S; HOWARD, H

    2005-10-11

    Modern weld controllers typically use current to control the weld process. SRS uses a legacy voltage control method. This task was undertaken to determine if the improvements in the weld control equipment could be implemented to provide improvements to the process control. The constant current mode of operation will reduce weld variability by about a factor of 4. The constant voltage welds were slightly hotter than the constant current welds of the same nominal current. The control mode did not appear to adversely affect the weld quality, but appropriate current ranges need to be established and a qualification methodology for both welding and shunt calibrations needs to be developed and documented.

  14. Laser reactive ablation deposition of titanium nitride and titanium carbide films

    NASA Astrophysics Data System (ADS)

    D'Anna, Emilia; Leggieri, Gilberto; Luches, Armando; Martino, Maurizio; Perrone, Alessio; Majni, Guiseppe; Mengucci, Paolo; Mihailescu, Ion N.

    1994-11-01

    Titanium nitride and titanium carbide films were deposited on silicon substrates by XeCl excimer laser reactive ablation of titanium in nitrogen and methane atmospheres, respectively. A series of 10,000 pulses at the fluence of approximately 5 J/cm2 and repetition rate of 10 Hz were directed to the target. The pressure in the chamber was fixed, during every irradiation series, at a given value within the range 6 X 10-4 - 10 mbar of N2 or CH4. Very flat films with thickness exceeding 1 micrometers were deposited. The structural characteristics of the deposited films were investigated by Rutherford backscattering spectrometry, scanning electron microscopy, and by x-ray diffraction. Under specific experimental conditions very pure nitride films were deposited.

  15. Modeling of Bullet Penetration in Explosively Welded Composite Armor Plate

    NASA Astrophysics Data System (ADS)

    Joshi, Vasant S.; Carney, Theodore C.

    2006-07-01

    Normal impact of high-speed armor piercing bullet on titanium-steel composite has been investigated using smooth particle hydrodynamics (SPH) code. The objective is to understand the effects of impact during the ballistic testing of explosively welded armor plates. These plates have significant microstructural differences within the weld region, heat-affected zone and the base metal. The variances result in substantial ductility, hardness and strength differences, important criteria in determining the failure mode, specifically whether it occurs at the joint or within the virgin base metal. Several configurations of composite plates with different material combinations were modeled. The results were used to modify the heat treatment process of explosively welded plates, making them more likely to survive impact.

  16. Modeling of bullet penetration in explosively welded composite armor plate

    NASA Astrophysics Data System (ADS)

    Joshi, Vasant; Carney, Theodore

    2005-07-01

    Normal impact of high-speed armor piercing bullet on titanium-steel composite has been investigated using smooth particle hydrodynamics (SPH) code. The objective is to understand the effects of multiple hits during the ballistic testing of explosively welded armor plates. These plates have significant micro-structural differences within the weld region, heat-affected zone and the base metal. The variances result in substantial ductility, hardness and strength differences, important criteria in determining the failure mode, specifically whether it occurs at the joint or within the virgin base metal. Several configurations of composite plates with different material combination had to be modeled. The results were used to modify the heat treatment process of explosively welded plates, making them more likely to survive multiple hits.

  17. Modeling of Bullet Penetration in Explosively Welded Composite Armor Plate

    SciTech Connect

    Joshi, Vasant S.; Carney, Theodore C.

    2006-07-28

    Normal impact of high-speed armor piercing bullet on titanium-steel composite has been investigated using smooth particle hydrodynamics (SPH) code. The objective is to understand the effects of impact during the ballistic testing of explosively welded armor plates. These plates have significant microstructural differences within the weld region, heat-affected zone and the base metal. The variances result in substantial ductility, hardness and strength differences, important criteria in determining the failure mode, specifically whether it occurs at the joint or within the virgin base metal. Several configurations of composite plates with different material combinations were modeled. The results were used to modify the heat treatment process of explosively welded plates, making them more likely to survive impact.

  18. Welding in Space Workshop

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.

    1990-01-01

    The potential was discussed for welding in space, its advantages and disadvantages, and what type of programs can benefit from the capability. Review of the various presentations and comments made in the course of the workshop suggests several routes to obtaining a better understanding of how welding processes can be used in NASA's initiatives in space. They are as follows: (1) development of a document identifying well processes and equipment requirements applicable to space and lunar environments; (2) more demonstrations of welding particular hardware which are to be used in the above environments, especially for space repair operations; (3) increased awareness among contractors responsible for building space equipment as to the potential for welding operations in space and on other planetary bodies; and (4) continuation of space welding research projects is important to maintain awareness within NASA that welding in space is viable and beneficial.

  19. WELDED JACKETED URANIUM BODY

    DOEpatents

    Gurinsky, D.H.

    1958-08-26

    A fuel element is presented for a neutronic reactor and is comprised of a uranium body, a non-fissionable jacket surrounding sald body, thu jacket including a portion sealed by a weld, and an inclusion in said sealed jacket at said weld of a fiux having a low neutron capture cross-section. The flux is provided by combining chlorine gas and hydrogen in the intense heat of-the arc, in a "Heliarc" welding muthod, to form dry hydrochloric acid gas.

  20. Thermo-mechanical modeling of the gas-tungsten-arc (GTA) welding process

    SciTech Connect

    Duncan, D.B.

    1980-01-18

    A fundamental study of gas-tungsten-arc (GTA) welding was undertaken. This was initiated with a review of the GTA welding process which lead to the decision to focus experimental and analytical efforts on stationary welds on a pure material. Pure nickel was selected for the test material. Temperature, strain, and distortion measurements were made during the formation of spot welds on circular plates. Transient thermal data were obtained with thermocouples, a radiation pyrometer, and from motion pictures. Local strain was observed qualitatively from Moire interference fringe patterns. Distortion during welding was measured with displacement gages and residual distortion with a profilometer. Experimental measurements are compared with predictions of thermal and mechanical finite element codes.

  1. Rolling-induced Face Centered Cubic Titanium in Hexagonal Close Packed Titanium at Room Temperature

    NASA Astrophysics Data System (ADS)

    Wu, H. C.; Kumar, A.; Wang, J.; Bi, X. F.; Tomé, C. N.; Zhang, Z.; Mao, S. X.

    2016-04-01

    Combining transmission electron microscopes and density functional theory calculations, we report the nucleation and growth mechanisms of room temperature rolling induced face-centered cubic titanium (fcc-Ti) in polycrystalline hexagonal close packed titanium (hcp-Ti). Fcc-Ti and hcp-Ti take the orientation relation: <0001>hcp||<001>fcc and , different from the conventional one. The nucleation of fcc-Ti is accomplished via pure-shuffle mechanism with a minimum stable thickness of three atomic layers, and the growth via shear-shuffle mechanisms through gliding two-layer disconnections or pure-shuffle mechanisms through gliding four-layer disconnections. Such phase transformation offers an additional plastic deformation mode comparable to twinning.

  2. Rolling-induced Face Centered Cubic Titanium in Hexagonal Close Packed Titanium at Room Temperature

    PubMed Central

    Wu, H. C.; Kumar, A.; Wang, J.; Bi, X. F.; Tomé, C. N.; Zhang, Z.; Mao, S. X.

    2016-01-01

    Combining transmission electron microscopes and density functional theory calculations, we report the nucleation and growth mechanisms of room temperature rolling induced face-centered cubic titanium (fcc-Ti) in polycrystalline hexagonal close packed titanium (hcp-Ti). Fcc-Ti and hcp-Ti take the orientation relation: 〈0001〉hcp||〈001〉fcc and , different from the conventional one. The nucleation of fcc-Ti is accomplished via pure-shuffle mechanism with a minimum stable thickness of three atomic layers, and the growth via shear-shuffle mechanisms through gliding two-layer disconnections or pure-shuffle mechanisms through gliding four-layer disconnections. Such phase transformation offers an additional plastic deformation mode comparable to twinning. PMID:27067515

  3. Dual wire welding torch and method

    DOEpatents

    Diez, Fernando Martinez; Stump, Kevin S.; Ludewig, Howard W.; Kilty, Alan L.; Robinson, Matthew M.; Egland, Keith M.

    2009-04-28

    A welding torch includes a nozzle with a first welding wire guide configured to orient a first welding wire in a first welding wire orientation, and a second welding wire guide configured to orient a second welding wire in a second welding wire orientation that is non-coplanar and divergent with respect to the first welding wire orientation. A method of welding includes moving a welding torch with respect to a workpiece joint to be welded. During moving the welding torch, a first welding wire is fed through a first welding wire guide defining a first welding wire orientation and a second welding wire is fed through a second welding wire guide defining a second welding wire orientation that is divergent and non-coplanar with respect to the first welding wire orientation.

  4. Pure Lovelock Kasner metrics

    NASA Astrophysics Data System (ADS)

    Camanho, Xián O.; Dadhich, Naresh; Molina, Alfred

    2015-09-01

    We study pure Lovelock vacuum and perfect fluid equations for Kasner-type metrics. These equations correspond to a single Nth order Lovelock term in the action in d=2N+1,2N+2 dimensions, and they capture the relevant gravitational dynamics when aproaching the big-bang singularity within the Lovelock family of theories. Pure Lovelock gravity also bears out the general feature that vacuum in the critical odd dimension, d=2N+1, is kinematic, i.e. we may define an analogue Lovelock-Riemann tensor that vanishes in vacuum for d=2N+1, yet the Riemann curvature is non-zero. We completely classify isotropic and vacuum Kasner metrics for this class of theories in several isotropy types. The different families can be characterized by means of certain higher order 4th rank tensors. We also analyze in detail the space of vacuum solutions for five- and six dimensional pure Gauss-Bonnet theory. It possesses an interesting and illuminating geometric structure and symmetries that carry over to the general case. We also comment on a closely related family of exponential solutions and on the possibility of solutions with complex Kasner exponents. We show that the latter imply the existence of closed timelike curves in the geometry.

  5. Sealing glasses for titanium and titanium alloys

    DOEpatents

    Brow, R.K.; McCollister, H.L.; Phifer, C.C.; Day, D.E.

    1997-07-15

    Barium lanthanoborate sealing-glass compositions are provided comprising various combinations (in terms of mole-%) of boron oxide (B{sub 2}O{sub 3}), barium oxide (BaO), lanthanum oxide (La{sub 2}O{sub 3}), and at least one other oxide selected from the group consisting of aluminum oxide (Al{sub 2}O{sub 3}), calcium oxide (CaO), lithium oxide (Li{sub 2}O), sodium oxide (Na{sub 2}O), silicon dioxide (SiO{sub 2}), or titanium dioxide (TiO{sub 2}). These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys having an improved aqueous durability and favorable sealing characteristics. Examples of the sealing-glass compositions are provided having coefficients of thermal expansion about that of titanium or titanium alloys, and with sealing temperatures less than about 900 C, and generally about 700--800 C. The barium lanthanoborate sealing-glass compositions are useful for components and devices requiring prolonged exposure to moisture or water, and for implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps). 1 fig.

  6. Sealing glasses for titanium and titanium alloys

    DOEpatents

    Brow, Richard K.; McCollister, Howard L.; Phifer, Carol C.; Day, Delbert E.

    1997-01-01

    Barium lanthanoborate sealing-glass compositions are provided comprising various combinations (in terms of mole-%) of boron oxide (B.sub.2 O.sub.3), barium oxide (BaO), lanthanum oxide (La.sub.2 O.sub.3), and at least one other oxide selected from the group consisting of aluminum oxide (Al.sub.2 O.sub.3), calcium oxide (CaO), lithium oxide (Li.sub.2 O), sodium oxide (Na.sub.2 O), silicon dioxide (SiO.sub.2), or titanium dioxide (TiO.sub.2). These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys having an improved aqueous durability and favorable sealing characteristics. Examples of the sealing-glass compositions are provided having coefficients of thermal expansion about that of titanium or titanium alloys, and with sealing temperatures less than about 900.degree. C., and generally about 700.degree.-800.degree. C. The barium lanthanoborate sealing-glass compositions are useful for components and devices requiring prolonged exposure to moisture or water, and for implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps).

  7. IR Spot Weld Inspect

    SciTech Connect

    Chen, Jian; Feng, Zhili

    2014-01-01

    In automotive industry, destructive inspection of spot welds is still the mandatory quality assurance method due to the lack of efficient non-destructive evaluation (NDE) tools. However, it is costly and time-consuming. Recently at ORNL, a new NDE prototype system for spot weld inspection using infrared (IR) thermography has been developed to address this problem. This software contains all the key functions that ensure the NDE system to work properly: system input/output control, image acquisition, data analysis, weld quality database generation and weld quality prediction, etc.

  8. Robot welding process control

    NASA Technical Reports Server (NTRS)

    Romine, Peter L.

    1991-01-01

    This final report documents the development and installation of software and hardware for Robotic Welding Process Control. Primary emphasis is on serial communications between the CYRO 750 robotic welder, Heurikon minicomputer running Hunter & Ready VRTX, and an IBM PC/AT, for offline programming and control and closed-loop welding control. The requirements for completion of the implementation of the Rocketdyne weld tracking control are discussed. The procedure for downloading programs from the Intergraph, over the network, is discussed. Conclusions are made on the results of this task, and recommendations are made for efficient implementation of communications, weld process control development, and advanced process control procedures using the Heurikon.

  9. IR Spot Weld Inspect

    Energy Science and Technology Software Center (ESTSC)

    2014-01-01

    In automotive industry, destructive inspection of spot welds is still the mandatory quality assurance method due to the lack of efficient non-destructive evaluation (NDE) tools. However, it is costly and time-consuming. Recently at ORNL, a new NDE prototype system for spot weld inspection using infrared (IR) thermography has been developed to address this problem. This software contains all the key functions that ensure the NDE system to work properly: system input/output control, image acquisition, datamore » analysis, weld quality database generation and weld quality prediction, etc.« less

  10. Physics of Fusion Welding

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.

    1986-01-01

    Applicabilities and limitations of three techniques analyzed. NASA technical memorandum discusses physics of electron-beam, gas/ tungsten-arc, and laser-beam welding. From comparison of capabilities and limitations of each technique with regard to various welding conditions and materials, possible to develop criteria for selecting best welding technique in specific application. All three techniques classified as fusion welding; small volume of workpiece melted by intense heat source. Heat source moved along seam, leaving in wake solid metal that joins seam edges together.

  11. Electric arc welding gun

    DOEpatents

    Luttrell, Edward; Turner, Paul W.

    1978-01-01

    This invention relates to improved apparatus for arc welding an interior joint formed by intersecting tubular members. As an example, the invention is well suited for applications where many similar small-diameter vertical lines are to be welded to a long horizontal header. The improved apparatus includes an arc welding gun having a specially designed welding head which is not only very compact but also produces welds that are essentially free from rolled-over solidified metal. The welding head consists of the upper end of the barrel and a reversely extending electrode holder, or tip, which defines an acute angle with the barrel. As used in the above-mentioned example, the gun is positioned to extend upwardly through the vertical member and the joint to be welded, with its welding head disposed within the horizontal header. Depending on the design of the welding head, the barrel then is either rotated or revolved about the axis of the vertical member to cause the electrode to track the joint.

  12. Explosive Welding of Pipes

    NASA Astrophysics Data System (ADS)

    Drennov, Oleg; Drennov, Andrey; Burtseva, Olga

    2013-06-01

    For connection by welding it is suggested to use the explosive welding method. This method is rather new. Nevertheless, it has become commonly used among the technological developments. This method can be advantageous (saving material and physical resources) comparing to its statical analogs (electron-beam welding, argon-arc welding, plasma welding, gas welding, etc.), in particular, in hard-to-reach areas due to their geographic and climatic conditions. Explosive welding of cylindrical surfaces is performed by launching of welded layer along longitudinal axis of construction. During this procedure, it is required to provide reliable resistance against radial convergent strains. The traditional method is application of fillers of pipe cavity, which are dense cylindrical objects having special designs. However, when connecting pipes consecutively in pipelines by explosive welding, removal of the fillers becomes difficult and sometimes impossible. The suggestion is to use water as filler. The principle of non-compressibility of liquid under quasi-dynamic loading is used. In one-dimensional gasdynamic and elastic-plastic calculations we determined non-deformed mass of water (perturbations, which are moving in the axial direction with sound velocity, should not reach the layer end boundaries for 5-7 circulations of shock waves in the radial direction). Linear dimension of the water layer from the zone of pipe coupling along axis in each direction is >= 2R, where R is the internal radius of pipe.

  13. Slow fatigue testing of titanium grade 29 in air and seawater

    SciTech Connect

    Atteraas, L.; Hersvik, G.; Solbakken, H.

    1999-07-01

    ASTM Grade 29 titanium has been fatigue tested in air and seawater at 110 C at a low frequency. The possible influence of seawater is completely masked by the fact that all the specimens of welded titanium, and most of the parent metal samples, had internal fracture initiations. Compared to the parent metal, the welded pipe specimens (5G orbital TIG) had a significantly lower fatigue life at the relatively high cyclic stress levels employed ({sigma}{sub max} = 0.85 {sigma}{sub y}). This is attributed to the presence of pores. Fractographic studies of failed weld metal specimens indicate that the fracture initiation takes place in the material immediately surrounding a pore, with an abrupt crack formation, marking the beginning of the crack growth phase. The duration of the crack initiation phase shows large variations, whereas the growth phase duration varies little.

  14. Sprayable titanium composition

    DOEpatents

    Tracy, Chester E.; Kern, Werner; Vibronek, Robert D.

    1980-01-01

    The addition of 2-ethyl-1-hexanol to an organometallic titanium compound dissolved in a diluent and optionally containing a lower aliphatic alcohol spreading modifier, produces a solution that can be sprayed onto a substrate and cured to form an antireflection titanium oxide coating having a refractive index of from about 2.0 to 2.2.

  15. In situ x-ray diffraction of shock-driven deformation and phase transformation in titanium

    NASA Astrophysics Data System (ADS)

    Bolme, Cynthia; Lazicki, Amy; Brown, Don; Gleason, Arianna; Cerreta, Ellen; Morrow, Ben; Ali, Suzanne; Swift, Damian; Nagler, Bob; Galtier, Eric; Granados, Eduardo; Milathianaki, Despina; Heimann, Phil

    2015-06-01

    Titanium alloys are employed in demanding engineering applications due to their high strength-to-weight ratio and their resistance to corrosion. Pure titanium and titanium with high levels of oxygen impurities were studied under laser-driven shock compression at the Matter in Extreme Conditions endstation at the Linac Coherent Light Source. In situ x-ray diffraction data were acquired during compression, showing the lattice-level response of titanium as it underwent plastic deformation and phase transformation. The kinetics of these processes and the influence of oxygen impurities on the deformation behavior will be presented.

  16. CHARACTERIZATION OF DEFECTS IN ALLOY 152, 52 AND 52M WELDS

    SciTech Connect

    Bruemmer, Stephen M.; Toloczko, Mychailo B.; Olszta, Matthew J.; Seffens, Rob J.; Efsing, Pal G.

    2009-08-27

    Defect distributions have been documented by optical metallography, scanning electron microscopy and electron backscatter diffraction in alloy 152 and 52 mockups welds, alloy 52 and 52M overlay mockups and an alloy 52M inlay. Primary defects were small cracks at grain boundaries except for more extensive cracking in the dilution zone of an alloy 52 overlay on 304SS. Detailed characterizations of the dilution zone cracks were performed by analytical transmission electron microscopy identifying grain boundary titanium-nitride precipitation associated with the intergranular separations. I. INTRODUCTION Weldments continue to be a primary location of stress-corrosion cracking (SCC) in light-water reactor systems. While problems related to heat-affected-zone (HAZ) sensitization and intergranular (IG) SCC of austenitic stainless alloys in boiling-water reactors (BWRs) have been significantly reduced, SCC has now been observed in HAZs of non-sensitized materials and in dissimilar metal welds where Ni-base alloy weld metals are used. IGSCC in weld metals has been observed in both BWRs and pressurized water reactors (PWRs) with recent examples for PWR pressure vessel penetrations producing the most concern. This has led to the replacement of alloy 600/182/82 welds with higher Cr, more corrosion-resistant replacement materials (alloy 690/152/52/52M). Complicating this issue has been a known susceptibility to cracking during welding [1-7] of these weld metals. There is a critical need for an improved understanding of the weld metal metallurgy and defect formation in Ni-base alloy welds to effectively assess long-term performance. A series of macroscopic to microscopic examinations were performed on available mockup welds made with alloy 52 or alloy 152 plus selected overlay and inlay mockups. The intent was to expand our understanding of weld metal structures in simulated LWR service components with a focus on as-welded defects. Microstructural features, defect distributions

  17. Inactivation of Escherichia coli by titanium dioxide photocatalytic oxidation.

    EPA Science Inventory

    Titanium dioxide in the anatase crystalline form was used as a photocatalyst to generate hydroxyl radicals in a flowthrough water reactor. Experiments were performed on pure cultures of Escherichia coli in dechlorinated tap water and a surface water sample to evaluate the disinfe...

  18. Surface Modifications and Their Effects on Titanium Dental Implants

    PubMed Central

    Jemat, A.; Ghazali, M. J.; Razali, M.; Otsuka, Y.

    2015-01-01

    This review covers several basic methodologies of surface treatment and their effects on titanium (Ti) implants. The importance of each treatment and its effects will be discussed in detail in order to compare their effectiveness in promoting osseointegration. Published literature for the last 18 years was selected with the use of keywords like titanium dental implant, surface roughness, coating, and osseointegration. Significant surface roughness played an important role in providing effective surface for bone implant contact, cell proliferation, and removal torque, despite having good mechanical properties. Overall, published studies indicated that an acid etched surface-modified and a coating application on commercial pure titanium implant was most preferable in producing the good surface roughness. Thus, a combination of a good surface roughness and mechanical properties of titanium could lead to successful dental implants. PMID:26436097

  19. The Growth Behavior of Titanium Boride Layers in α and β Phase Fields of Titanium

    NASA Astrophysics Data System (ADS)

    Lv, Xiaojun; Hu, Lingyun; Shuang, Yajing; Liu, Jianhua; Lai, Yanqing; Jiang, Liangxing; Li, Jie

    2016-07-01

    In this study, the commercially pure titanium was successfully electrochemical borided in a borax-based electrolyte. The process was carried out at a constant cathodic current density of 300 mA cm-2 and at temperatures of 1123 K and 1223 K (850 °C and 950 °C) for 0.5, 1, 2, 3, and 5 hours. The growth behavior of titanium boride layers in the α phase field of titanium was compared with that in the β phase field. After boriding, the presence of both the TiB2 top layer and TiB whisker sub-layer was confirmed by the X-ray diffraction (XRD) and scanning electron microscope. The relationship between the thickness of boride layers and boriding time was found to have a parabolic character in both α and β phase fields of titanium. The TiB whiskers showed ultra-fast growth rate in the β phase field. Its growth rate constant was found to be as high as 3.2002 × 10-13 m2 s-1. Besides, the chemical resistance of the TiB2 layer on the surface of titanium substrate was characterized by immersion tests in molten aluminum.

  20. The Growth Behavior of Titanium Boride Layers in α and β Phase Fields of Titanium

    NASA Astrophysics Data System (ADS)

    Lv, Xiaojun; Hu, Lingyun; Shuang, Yajing; Liu, Jianhua; Lai, Yanqing; Jiang, Liangxing; Li, Jie

    2016-04-01

    In this study, the commercially pure titanium was successfully electrochemical borided in a borax-based electrolyte. The process was carried out at a constant cathodic current density of 300 mA cm-2 and at temperatures of 1123 K and 1223 K (850 °C and 950 °C) for 0.5, 1, 2, 3, and 5 hours. The growth behavior of titanium boride layers in the α phase field of titanium was compared with that in the β phase field. After boriding, the presence of both the TiB2 top layer and TiB whisker sub-layer was confirmed by the X-ray diffraction (XRD) and scanning electron microscope. The relationship between the thickness of boride layers and boriding time was found to have a parabolic character in both α and β phase fields of titanium. The TiB whiskers showed ultra-fast growth rate in the β phase field. Its growth rate constant was found to be as high as 3.2002 × 10-13 m2 s-1. Besides, the chemical resistance of the TiB2 layer on the surface of titanium substrate was characterized by immersion tests in molten aluminum.

  1. 7 CFR 917.8 - Pure grower or pure producer.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Agreements and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE FRESH PEARS AND PEACHES GROWN IN CALIFORNIA Order Regulating Handling Definitions § 917.8 Pure grower or pure producer. (a) For peaches,...

  2. 7 CFR 917.8 - Pure grower or pure producer.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Agreements and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE FRESH PEARS AND PEACHES GROWN IN CALIFORNIA Order Regulating Handling Definitions § 917.8 Pure grower or pure producer. (a) For peaches,...

  3. DC arc weld starter

    DOEpatents

    Campiotti, Richard H.; Hopwood, James E.

    1990-01-01

    A system for starting an arc for welding uses three DC power supplies, a high voltage supply for initiating the arc, an intermediate voltage supply for sustaining the arc, and a low voltage welding supply directly connected across the gap after the high voltage supply is disconnected.

  4. Advanced Welding Torch

    NASA Technical Reports Server (NTRS)

    1996-01-01

    In order to more easily join the huge sections of the Space Shuttle external tank, Marshall Space Flight Center initiated development of the existing concept of Variable Polarity Plasma Arc (VPPA) welding. VPPA welding employs a variable current waveform that allows the system to operate for preset time increments in either of two polarity modes for effective joining of light alloys.

  5. Explosive Welding of Pipes

    NASA Astrophysics Data System (ADS)

    Burtseva, Olga

    2007-06-01

    For connection by welding it is suggested to use the explosive welding method. This method is rather new. Nevertheless, it has become commonly used among the technological developments. This method can be advantageous (saving material and physical resources) comparing to its statical analogs (electron-beam welding, argon-arc welding, plasma welding, gas welding, etc.), in particular, in hard-to-reach areas due to their geographic and climatic conditions. The suggestion is to use water as filler. The principle of non-compressibility of liquid under quasi-dynamic loading is used. In one-dimensional gasdynamic and elastic-plastic calculations we determined non-deformed mass of water (perturbations, which are moving in the axial direction with sound velocity, should not reach the layer end boundaries for 5-7 circulations of shock waves in the radial direction). Linear dimension of the water layer from the zone of pipe coupling along axis in each direction is >= 2R, where R is the internal radius of pipe. Model experiments with pipes having radii R = 57 mm confirmed results of the calculations and the possibility in principle to weld pipes by explosion with use of water as filler. Reduction of pipe diameter after dynamic loading and explosive welding was ˜2%.

  6. Welding: Scope and Sequence.

    ERIC Educational Resources Information Center

    Nashville - Davidson County Metropolitan Public Schools, TN.

    Intended for use by all welding instructors in the Metropolitan Nashville Public Schools, this guide provides a sequential listing of course content and scope. A course description provides a brief overview of the content of the courses offered in the welding program. General course objectives are then listed. Outlines of the course content are…

  7. Laser Welding in Space

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.; Kaukler, William F.

    1989-01-01

    Solidification type welding process experiments in conditions of microgravity were performed. The role of convection in such phenomena was examined and convective effects in the small volumes obtained in the laser weld zone were observed. Heat transfer within the weld was affected by acceleration level as indicated by the resulting microstructure changes in low gravity. All experiments were performed such that both high and low gravity welds occurred along the same weld beam, allowing the effects of gravity alone to be examined. Results indicate that laser welding in a space environment is feasible and can be safely performed IVA or EVA. Development of the hardware to perform the experiment in a Hitchhiker-g platform is recomended as the next step. This experiment provides NASA with a capable technology for welding needs in space. The resources required to perform this experiment aboard a Shuttle Hitchhiker-pallet are assessed. Over the four year period 1991 to 1994, it is recommended that the task will require 13.6 manyears and $914,900. In addition to demonstrating the technology and ferreting out the problems encountered, it is suggested that NASA will also have a useful laser materials processing facility for working with both the scientific and the engineering aspects of materials processing in space. Several concepts are also included for long-term optimization of available solar power through solar pumping solid state lasers directly for welding power.

  8. Vocational Preparation Curriculum: Welding.

    ERIC Educational Resources Information Center

    Usoro, Hogan

    Designed to be a workable guide for instructors serving the occupational needs of various categories of disadvantaged and handicapped students, this welding curriculum contains fourteen units of self-paced and self-contained instructional materials. The instructional units cover the following topics: job opportunities in welding, safety rules in…

  9. Welding Tubes In Place

    NASA Technical Reports Server (NTRS)

    Meredith, R.

    1984-01-01

    Special welding equipment joins metal tubes that carry pressurized cyrogenic fluids. Equipment small enough to be used in confined spaces in which such tubes often mounted. Welded joints lighter in weight and more leak-proof than joints made with mechanical fittings.

  10. Fine welding with lasers.

    PubMed

    MacLellan, D

    2008-01-01

    The need for micro joining metallic alloys for surgical instruments, implants and advanced medical devices is driving a rapid increase in the implementation of laser welding technology in research, development and volume production. This article discusses the advantages of this welding method and the types of lasers used in the process. PMID:18557404

  11. Weld-Fill Program

    NASA Technical Reports Server (NTRS)

    Maslakowski, John E.

    1994-01-01

    ROCKFILL is software that calculates key robot weld information. Its easy-to-use menu system enables robot operator to estimate better number of passes, amount of wire, arc time, and amount of heat put into particular weld. Designed to operate on work-cell personal computer of robot and requires no documentation or training. Written in C language.

  12. The effect of welding parameters on penetration in GTA welds

    SciTech Connect

    Shirali, A.A. ); Mills, K.C. )

    1993-07-01

    The effect of various welding parameters on the penetration of GTA welds has been investigated. Increases in welding speed were found to reduce penetration; however, increases in welding current were observed to increase the penetration in high sulfur (HS) casts and decrease penetration in low sulfur (LS) steels. Plots of penetration as a function of increasing linear energy (the heat supplied per unit length of weld) revealed a similar trend with increased penetration in HS casts, but the penetration in LS casts was unaffected by increases in linear energy. These results support the Burgardt-Heiple proposition that changes in welding parameters on penetration can be explained in terms of their effect, sequentially, on the temperature gradient and the Marangoni forces operating in the weld pool. Increases in arc length were found to decrease weld penetration regardless of the sulfur concentration of the steel, and the effects of electrode geometry and welding position on weld penetration were also investigated.

  13. Method for welding beryllium

    DOEpatents

    Dixon, R.D.; Smith, F.M.; O`Leary, R.F.

    1997-04-01

    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. 9 figs.

  14. Welding Sensor System

    NASA Technical Reports Server (NTRS)

    1993-01-01

    A system originally designed for welding components of the huge Space Shuttle external tank led to a laser-based automated welder for industrial use. A laser sensor tracks the seam where two pieces of metal are to be joined, measures gaps, misfits and automatically corrects welding of torch distance and height. A small industrial computer translates the sensor's information to the weld head and records and displays weld data for control purposes and analysis. The system was modified for commercial use by Marshall Space Flight Center (MSFC), Martin Marietta and Applied Research, Inc., which produces the commercial system. Applications are in industrial welding processes that require repetitive operations and a high degree of reliability.

  15. Welds in thermoplastic composite materials

    NASA Astrophysics Data System (ADS)

    Taylor, N. S.

    Welding methods are reviewed that can be effectively used for joining of thermoplastic composites and continuous-fiber thermoplastics. Attention is given to the use of ultrasonic, vibration, hot-plate, resistance, and induction welding techniques. The welding techniques are shown to provide complementary weld qualities for the range of thermoplastic materials that are of interest to industrial and technological applications.

  16. Alternating-Polarity Arc Welding

    NASA Technical Reports Server (NTRS)

    Schwinghamer, R. J.

    1987-01-01

    Brief reversing polarity of welding current greatly improves quality of welds. NASA technical memorandum recounts progress in art of variable-polarity plasma-arc (VPPA) welding, with emphasis on welding of aluminum-alloy tanks. VPPA welders offer important advantages over conventional single-polarity gas/tungsten arc welders.

  17. Vacuum Gas Tungsten Arc Welding

    NASA Technical Reports Server (NTRS)

    Weeks, J. L.; Todd, D. T.; Wooten, J. R.

    1997-01-01

    A two-year program investigated vacuum gas tungsten arc welding (VGTAW) as a method to modify or improve the weldability of normally difficult-to-weld materials. After a vacuum chamber and GTAW power supply were modified, several difficult-to-weld materials were studied and key parameters developed. Finally, Incoloy 903 weld overlays were produced without microfissures.

  18. Ultrasonic seam welding. Final report

    SciTech Connect

    Darner, G.S.

    1980-06-01

    Ultrasonic seam welding has been evaluated for making continuous seam welds on aluminum and copper-foil conductors. A seam welding system has been designed and fabricated, weldable material combinations have been identified, and the process parameters for welding materials applicable to flat cable production have been established.

  19. Argon Welding Inside A Workpiece

    NASA Technical Reports Server (NTRS)

    Morgan, Gene E.

    1988-01-01

    Canopies convert large hollow workpiece into inert-gas welding chamber. Large manifold serves welding chamber for attachment of liner parts in argon atmosphere. Every crevice, opening and passageway provided with argon-rich environment. Weld defects and oxidation dramatically reduced; also welding time reduced.

  20. Solidification of underwater wet welds

    SciTech Connect

    Pope, A.M.; Medeiros, R.C. de; Liu, S.

    1995-12-31

    It is well known that the shape of a weld pool can influence the microstructure and segregation pattern of the final solidified weld metal. Mechanical properties and susceptibility to defects are consequently affected by the solidification mode of the weld. In this work the solidification behavior of weld beads deposited in air and underwater wet welding using rutile electrodes were compared. The welds were deposited by gravity feed, on low carbon, manganese steel plates using similar welding conditions. Macroscopic observation of the weld craters showed that welds deposited in air presented an elliptical weld pool. The underwater wet welds, on the other hand, solidified with a tear drop shape. Although the welds differed in shape, their lengths were approximately the same. Microscopic examinations carried out on transverse, normal and longitudinal sections revealed a coarser columnar grain structure in the underwater welds. These results suggest that the tear-drop shaped pool induced solidification in a preferred orientation with segregation more likely in welds deposited under wet conditions. This change in weld pool geometry can be explained by the surface heat loss conditions that occur in a wet weld: slower when covered by the steam bubble and faster in the region in contact with water behind the pool.

  1. Laser-Modified Black Titanium Oxide Nanospheres and Their Photocatalytic Activities under Visible Light.

    PubMed

    Chen, Xing; Zhao, Dongxu; Liu, Kewei; Wang, Chunrui; Liu, Lei; Li, Binghui; Zhang, Zhenzhong; Shen, Dezhen

    2015-07-29

    A facile pulse laser ablation approach for preparing black titanium oxide nanospheres, which could be used as photocatalysts under visible light, is proposed. The black titanium oxide nanospheres are prepared by pulsed-laser irradiation of pure titanium oxide in suspended aqueous solution. The crystalline phases, morphology, and optical properties of the obtained nanospheres are characterized by means of X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), and UV-vis-NIR diffuse reflectance spectroscopy. It is shown that high-energy laser ablation of titanium oxide suspended solution benefited the formation of Ti(3+) species and surface disorder on the surface of the titanium oxide nanospheres. The laser-modified black titanium oxide nanospheres could absorb the full spectrum of visible light, thus exhibiting good photocatalytic performance under visible light. PMID:26132217

  2. Grinding Parts For Automatic Welding

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.; Hoult, William S.

    1989-01-01

    Rollers guide grinding tool along prospective welding path. Skatelike fixture holds rotary grinder or file for machining large-diameter rings or ring segments in preparation for welding. Operator grasps handles to push rolling fixture along part. Rollers maintain precise dimensional relationship so grinding wheel cuts precise depth. Fixture-mounted grinder machines surface to quality sufficient for automatic welding; manual welding with attendant variations and distortion not necessary. Developed to enable automatic welding of parts, manual welding of which resulted in weld bead permeated with microscopic fissures.

  3. Immediate rehabilitation of the edentulous mandible using Ankylos SynCone telescopic copings and intraoral welding: a pilot study.

    PubMed

    Degidi, Marco; Nardi, Diego; Sighinolfi, Gianluca; Piattelli, Adriano

    2012-12-01

    The aim of this prospective study was to assess the suitability of immediate rehabilitation of the edentulous mandible using SynCone copings and the intraoral welding technique. Patients with an edentulous mandible were fitted with a removable restoration supported by an intraorally welded titanium bar. Copings were connected to their respective SynCone 5-degree abutments and then welded to a titanium bar using an intraoral welding unit. This framework was used to support the definitive restoration, which was delivered on the day of implant placement. Restoration success and survival, implant success, and biologic or technical complications were assessed immediately after surgery and at 6 and 12 months. Twenty-two patients were consecutively treated with 88 immediately loaded implants. No acrylic resin fractures or radiographically detectable alterations of the welded frameworks were present in the 22 restorations delivered. One implant (1.1%) failed 1 month after surgery; all remaining implants (98.9%) were clinically stable at the 12-month follow-up. Within its limitations, this pilot study demonstrated that it is possible to successfully rehabilitate the edentulous mandible on the day of surgery with a definitive restoration supported by an intraorally welded titanium framework and SynCone 5-degree abutments. PMID:23057062

  4. Impact Modeling of Spot Welds

    NASA Astrophysics Data System (ADS)

    Yancey, Robert N.

    2004-06-01

    Resistance spot welds in most current finite element crash models are characterized as a rigid link at the location of the weld which transfers the load but is not designed to fail. Newer weld elements in the popular finite element analysis codes include the option of incorporating a failure criteria for the weld element. As many automotive companies move towards the use of high-strength steels, the dynamic behavior of the spot welds will become increasingly important and the failure of any welds should be incorporated during the simulation. The failure criteria will be influenced by mesh size, weld element properties, weld element type, surrounding material properties, strain rate, and weld placement. The influence of some of these parameters using current spot weld modeling techniques will be discussed along with recommendations for future work in this area.

  5. Pure Autonomic Failure.

    PubMed

    Thaisetthawatkul, Pariwat

    2016-08-01

    Pure autonomic failure (PAF) is a rare sporadic neurodegenerative autonomic disorder characterized by slowly progressive pan autonomic failure without other features of neurologic dysfunctions. The main clinical symptoms result from neurogenic orthostatic hypotension and urinary and gastrointestinal autonomic dysfunctions. Autonomic failure in PAF is caused by neuronal degeneration of pre- and postganglionic sympathetic and parasympathetic neurons in the thoracic spinal cord and paravertebral autonomic ganglia. The presence of Lewy bodies and α-synuclein deposits in these neural structures suggests that PAF is one of Lewy body synucleinopathies, examples of which include multiple system atrophy, Parkinson disease, and Lewy body disease. There is currently no specific treatment to stop progression in PAF. Management of autonomic symptoms is the mainstay of treatment and includes management of orthostatic hypotension and supine hypertension. The prognosis for survival of PAF is better than for the other synucleinopathies. PMID:27338613

  6. Calibration Fixture For Welding Robot

    NASA Technical Reports Server (NTRS)

    Holly, Krisztina J.

    1990-01-01

    Compact, lightweight device used in any position or orientation. Calibration fixture designed for use on robotic gas/tungsten-arc welding torch equipped with vision-based seam-tracking system. Through optics in hollow torch cylinder, video camera obtains image of weld, viewing along line of sight coaxial with welding electrode. Attaches to welding-torch cylinder in place of gas cup normally attached in use. By use of longer or shorter extension tube, fixture accommodates welding electrode of unusual length.

  7. External attachment of titanium sheathed thermocouples to zirconium nuclear fuel rods for the LOFT reactor

    SciTech Connect

    Welty, R. K.

    1980-01-01

    The Exxon Nuclear Company, Inc., acting as a Subcontractor to EG and G Idaho Inc., Idaho National Engineering Laboratory, Idaho Falls, Idaho, has developed a welding process to attach titanium sheathed thermocouples to the outside of the zircaloy clad fuel rods. The fuel rods and thermocouples are used to test simulated loss-of-coolant accident (LOCA) conditions in a pressurized water reactor (LOFT Reactor, Idaho National Laboratory). A laser beam was selected as the optimum welding process because of the extremely high energy input per unit volume that can be achieved allowing local fusion of a small area irrespective of the difference in material thickness to be joined. A commercial pulsed laser and energy control system was installed along with specialized welding fixtures. Laser room facility requirements and tolerances were established. Performance qualifications, and detailed welding procedures were also developed. Product performance tests were conducted to assure that engineering design requirements could be met on a production basis.

  8. Microstructure and Strength Characteristics of Alloy 617 Welds

    SciTech Connect

    T.C. Totemeier; H. Tian; D.E. Clark; J.A. Simpson

    2005-06-01

    Three types of high-temperature joints were created from alloy 617 base metal: fusion welds, braze joints, and diffusion bonds. The microstructures of all joint types and tensile properties of fusion welds and braze joints were characterized. Sound fusion welds were created by the GTAW process with alloy 617 filler wire. Cross-weld tensile strengths were equal to the parent metal at temperatures of 25, 800, and 1000°C; ductilities of the joints were only slightly lower than that of the parent metal. Failure occurred in the weld fusion zone at room temperature and in the parent metal at elevated temperatures. Incomplete wetting occurred in joints produced by vacuum brazing using AWS BNi-1 braze alloy, believed to be due to tenacious Al and Ti oxide formation. Incompletely bonded butt joints showed relatively poor tensile properties. A second set of braze joints has been created with faying surfaces electroplated with pure Ni prior to brazing; characterization of these joints is in progress. Conditions resulting in good diffusion bonds characterized by grain growth across the bondline and no porosity were determined: vacuum bonding at 1150°C for 3 hours with an initial uniaxial stress of 20 MPa (constant ram displacement). A 15 µm thick pure Ni interlayer was needed to achieve grain growth across the bondline. Tensile testing of diffusion bonds is in progress

  9. Electroplating on titanium alloy

    NASA Technical Reports Server (NTRS)

    Lowery, J. R.

    1971-01-01

    Activation process forms adherent electrodeposits of copper, nickel, and chromium on titanium alloy. Good adhesion of electroplated deposits is obtained by using acetic-hydrofluoric acid anodic activation process.

  10. Weld analysis and control system

    NASA Technical Reports Server (NTRS)

    Kennedy, Larry Z. (Inventor); Rodgers, Michael H. (Inventor); Powell, Bradley W. (Inventor); Burroughs, Ivan A. (Inventor); Goode, K. Wayne (Inventor)

    1994-01-01

    The invention is a Weld Analysis and Control System developed for active weld system control through real time weld data acquisition. Closed-loop control is based on analysis of weld system parameters and weld geometry. The system is adapted for use with automated welding apparatus having a weld controller which is capable of active electronic control of all aspects of a welding operation. Enhanced graphics and data displays are provided for post-weld analysis. The system provides parameter acquisition, including seam location which is acquired for active torch cross-seam positioning. Torch stand-off is also monitored for control. Weld bead and parent surface geometrical parameters are acquired as an indication of weld quality. These parameters include mismatch, peaking, undercut, underfill, crown height, weld width, puddle diameter, and other measurable information about the weld puddle regions, such as puddle symmetry, etc. These parameters provide a basis for active control as well as post-weld quality analysis and verification. Weld system parameters, such as voltage, current and wire feed rate, are also monitored and archived for correlation with quality parameters.

  11. Influence of nitrogen in the shielding gas on corrosion resistance of duplex stainless steel welds

    SciTech Connect

    Bhatt, R.B.; Kamat, H.S.; Ghosal, S.K.; De, P.K.

    1999-10-01

    The influence of nitrogen in shielding gas on the corrosion resistance of welds of a duplex stainless steel (grade U-50), obtained by gas tungsten arc (GTA) with filler wire, autogenous GTA (bead-on-plate), electron beam welding (EBW), and microplasma techniques, has been evaluated in chloride solutions at 30 C. Pitting attack has been observed in GTA, electron beam welding, and microplasma welds when welding has been carried out using pure argon as the shielding gas. Gas tungsten arc welding with 5 to 10% nitrogen and 90 to 95% argon, as the shielding gas, has been found to result in an improved pitting corrosion resistance of the weldments of this steel. However, the resistance of pitting of autogenous welds (bead-on-plate) obtained in pure argon as the shielding gas has been observed to remain unaffected. Microscopic examination, electron probe microanalysis (EPMA), and x-ray diffraction studies have revealed that the presence of nitrogen in the shielding gas in the GTA welds not only modifies the microstructure and the austenite to ferrite ratio but also results in a nearly uniform distribution of the various alloying elements, for example, chromium, nickel, and molybdenum among the constituent phases, which are responsible for improved resistance to pitting corrosion.

  12. Influence of nitrogen in the shielding gas on corrosion resistance of duplex stainless steel welds

    NASA Astrophysics Data System (ADS)

    Bhatt, R. B.; Kamat, H. S.; Ghosal, S. K.; de, P. K.

    1999-10-01

    The influence of nitrogen in shielding gas on the corrosion resistance of welds of a duplex stainless steel (grade U-50), obtained by gas tungsten arc (GTA) with filler wire, autogenous GTA (bead-on-plate), electron beam welding (EBW), and microplasma techniques, has been evaluated in chloride solutions at 30 °C. Pitting attack has been observed in GTA, electron beam welding, and microplasma welds when welding has been carried out using pure argon as the shielding gas. Gas tungsten arc welding with 5 to 10% nitrogen and 90 to 95% argon, as the shielding gas, has been found to result in an improved pitting corrosion resistance of the weldments of this steel. However, the resistance to pitting of autogenous welds (bead-on-plate) obtained in pure argon as the shielding gas has been observed to remain unaffected. Microscopic examination, electron probe microanalysis (EPMA), and x-ray diffraction studies have revealed that the presence of nitrogen in the shielding gas in the GTA welds not only modifies the microstructure and the austenite to ferrite ratio but also results in a nearly uniform distribution of the various alloying elements, for example, chromium, nickel, and molybdenum among the constitutent phases, which are responsible for improved resistance to pitting corrosion.

  13. Defects in ion-implanted hcp-titanium: A first-principles study of electronic structures

    NASA Astrophysics Data System (ADS)

    Raji, Abdulrafiu T.; Mazzarello, Riccardo; Scandolo, Sandro; Nsengiyumva, Schadrack; Härting, Margit; Britton, David T.

    2011-12-01

    The electronic structures of hexagonal closed-packed (h.c.p) titanium containing a vacancy and krypton impurity atoms at various insertion sites are calculated by first-principles methods in the framework of the density-functional theory (DFT). The density of states (DOS) for titanium containing a vacancy defect shows resonance-like features. Also, the bulk electron density decreases from ˜0.15/Å 3 to ˜0.05/Å 3 at the vacancy centre. Electronic structure calculations have been performed to investigate what underlies the krypton site preference in titanium. The DOS of the nearest-neighbour (NN) titanium atoms to the octahedral krypton appears to be less distorted (relative to pure titanium) when compared to the NN titanium atoms to the tetrahedral krypton. The electronic density deformation maps show that polarization of the titanium atoms is stronger when the krypton atom is located at the tetrahedral site. Since krypton is a closed-shell atom, thus precluding any bonding with the titanium atoms, we may conclude that the polarization of the electrons in the vicinity of the inserted krypton atoms and the distortion of the DOS of the NN titanium atoms to the krypton serve to indicate which defect site is preferred when a krypton atom is inserted into titanium. Based on these considerations, we conclude that the substitutional site is the most favourable one, and the octahedral is the preferred interstitial site, in agreement with recent DFT calculations of the energetics of krypton impurity sites.

  14. Model of Layered Weld Formation Under Narrow Gap Pulse Welding

    NASA Astrophysics Data System (ADS)

    Krampit, A. G.

    2016-04-01

    The model parameters of narrow gap pulse welding can be divided into input, internal and output ones. The breadth of gap, that is, clearance breadth between upright edges is one of key parameters securing high quality of a weld joint. The paper presents theoretical outcomes for the model of layered weld formation under narrow gap pulse welding. Based on these studies is developed model of processes, which occur in the weld pool under pulse grove welding. It comprises the scheme of liquid metal motion in the weld pool, scheme of fusion with the side edge and in the bottom part, and the scheme of welding current impulse effect on the structure of a weld joint.

  15. Titanium Allergy: A Literature Review

    PubMed Central

    Goutam, Manish; Giriyapura, Chandu; Mishra, Sunil Kumar; Gupta, Siddharth

    2014-01-01

    Titanium has gained immense popularity and has successfully established itself as the material of choice for dental implants. In both medical and dental fields, titanium and its alloys have demonstrated success as biomedical devices. Owing to its high resistance to corrosion in a physiological environment and the excellent biocompatibility that gives it a passive, stable oxide film, titanium is considered the material of choice for intraosseous use. There are certain studies which show titanium as an allergen but the resources to diagnose titanium sensivity are very limited. Attention is needed towards the development of new and precise method for early diagnosis of titanium allergy and also to find out the alternative biomaterial which can be used in place of titanium. A review of available articles from the Medline and PubMed database was done to find literature available regarding titanium allergy, its diagnosis and new alternative material for titanium. PMID:25484409

  16. Interfacial microstructure and properties of copper clad steel produced using friction stir welding versus gas metal arc welding

    SciTech Connect

    Shen, Z.; Chen, Y.; Haghshenas, M.; Nguyen, T.; Galloway, J.; Gerlich, A.P.

    2015-06-15

    A preliminary study compares the feasibility and microstructures of pure copper claddings produced on a pressure vessel A516 Gr. 70 steel plate, using friction stir welding versus gas metal arc welding. A combination of optical and scanning electron microscopy is used to characterize the grain structures in both the copper cladding and heat affected zone in the steel near the fusion line. The friction stir welding technique produces copper cladding with a grain size of around 25 μm, and no evidence of liquid copper penetration into the steel. The gas metal arc welding of copper cladding exhibits grain sizes over 1 mm, and with surface microcracks as well as penetration of liquid copper up to 50 μm into the steel substrate. Transmission electron microscopy reveals that metallurgical bonding is produced in both processes. Increased diffusion of Mn and Si into the copper cladding occurs when using gas metal arc welding, although some nano-pores were detected in the FSW joint interface. - Highlights: • Cladding of steel with pure copper is possible using either FSW or GMAW. • The FSW yielded a finer grain structure in the copper, with no evidence of cracking. • The FSW joint contains some evidence of nano-pores at the interface of the steel/copper. • Copper cladding by GMAW contained surface cracks attributed to high thermal stresses. • The steel adjacent to the fusion line maintained a hardness value below 248 HV.

  17. Robotics for welding research

    SciTech Connect

    Braun, G.; Jones, J.

    1984-09-01

    The welding metallurgy research and education program at Colorado School of Mines (CSM) is helping industries make the transition toward automation by training students in robotics. Industry's interest is primarily in pick and place operations, although robotics can increase efficiency in areas other than production. Training students to develop fully automated robotic welding systems will usher in new curriculum requirements in the area of computers and microprocessors. The Puma 560 robot is CSM's newest acquisition for welding research 5 references, 2 figures, 1 table.

  18. APPARATUS FOR ARC WELDING

    DOEpatents

    Lingafelter, J.W.

    1960-04-01

    An apparatus is described in which a welding arc created between an annular electrode and a workpiece moves under the influence of an electromagnetic field about the electrode in a closed or annular path. This mode of welding is specially suited to the enclosing of nuclear-fuel slugs in a protective casing. For example, a uranium slug is placed in an aluminum can, and an aluminum closure is welded to the open end of the can along a closed or annular path conforming to the periphery of the end closure.

  19. Weld Wire Investigation Summary

    SciTech Connect

    Cunningham, M.A.

    1999-03-22

    After GTA welding reservoir A production/process prove-in assemblies, X-ray examination detected a lack of sidewall fusion. After examining several possible causes, it was determined that the weld wire filler metal was responsible, particularly the wire cleaning process. The final conclusion was that the filler wire must be abrasively cleaned in a particular manner to perform as required. The abrasive process was incorporated into the wire material specification, ensuring consistency for all reservoir GTA welding at AlliedSignal Federal Manufacturing and Technologies (FM and T).

  20. Thermal stir welding apparatus

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor)

    2011-01-01

    A welding method and apparatus are provided for forming a weld joint between first and second elements of a workpiece. The method includes heating the first and second elements to form an interface of material in a plasticized or melted state interface between the elements. The interface material is then allowed to cool to a plasticized state if previously in a melted state. The interface material, while in the plasticized state, is then mixed, for example, using a grinding/extruding process, to remove any dendritic-type weld microstructures introduced into the interface material during the heating process.

  1. Thermal stir welding process

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor)

    2012-01-01

    A welding method is provided for forming a weld joint between first and second elements of a workpiece. The method includes heating the first and second elements to form an interface of material in a plasticized or melted state interface between the elements. The interface material is then allowed to cool to a plasticized state if previously in a melted state. The interface material, while in the plasticized state, is then mixed, for example, using a grinding/extruding process, to remove any dendritic-type weld microstructures introduced into the interface material during the heating process.

  2. Welding Stainless Steels and Refractory Metals Using Diode-Pumped Continuous Wave Nd:YAG Lasers

    SciTech Connect

    Palmer, T A; Elmer, J W; Pong, R; Gauthier, M D

    2004-09-27

    This report provides an overview of a series of developmental welding studies performed on a 2.2 kW Rofin Sinar DY-022 Diode Pumped Continuous Wave (CW) Nd:YAG welder at Lawrence Livermore National Laboratory (LLNL). Several materials systems, ranging from refractory metals, such as commercially pure tantalum and vanadium, to austenitic stainless steels, including both 304L and 21-6-9 grades, are examined. Power input and travel speed are systematically varied during the welding of each materials system, and the width, depth, and cross sectional area of the resulting weld fusion zones are measured. These individual studies are undertaken in order to characterize the response of the welder to changes in these welding parameters for a range of materials and to determine the maximum depth of penetration of which this welder is capable in each materials system. The maximum weld depths, which are on the order of 5.4 mm, are observed in the 21-6-9 austenitic stainless steel at the maximum laser power setting (2200 W) and a slow travel speed (6.4 mm/sec). The next highest weld depth is observed in the 304L stainless steel, followed by that observed in the vanadium and, finally, in the tantalum. Porosity, which is attributed to the collapse of the keyhole during welding, is also observed in the welds produced in tantalum, vanadium, and 304L stainless steel. Only the 21-6-9 austenitic stainless steel welds displayed little or no porosity over the range of welding parameters. Comparisons with similar laser welding systems are also made for several of these same materials systems. When compared with the welds produced by these other systems, the LLNL system typically produces welds of an equivalent or slightly higher depth.

  3. Titanium by design: TRIP titanium alloy

    NASA Astrophysics Data System (ADS)

    Tran, Jamie

    Motivated by the prospect of lower cost Ti production processes, new directions in Ti alloy design were explored for naval and automotive applications. Building on the experience of the Steel Research Group at Northwestern University, an analogous design process was taken with titanium. As a new project, essential kinetic databases and models were developed for the design process and used to create a prototype design. Diffusion kinetic models were developed to predict the change in phase compositions and microstructure during heat treatment. Combining a mobility database created in this research with a licensed thermodynamic database, ThermoCalc and DICTRA software was used to model kinetic compositional changes in titanium alloys. Experimental diffusion couples were created and compared to DICTRA simulations to refine mobility parameters in the titanium mobility database. The software and database were able to predict homogenization times and the beta→alpha plate thickening kinetics during cooling in the near-alpha Ti5111 alloy. The results of these models were compared to LEAP microanalysis and found to be in reasonable agreement. Powder metallurgy was explored using SPS at GM R&D to reduce the cost of titanium alloys. Fully dense Ti5111 alloys were produced and achieved similar microstructures to wrought Ti5111. High levels of oxygen in these alloys increased the strength while reducing the ductility. Preliminary Ti5111+Y alloys were created, where yttrium additions successfully gettered excess oxygen to create oxides. However, undesirable large oxides formed, indicating more research is needed into the homogeneous distribution of the yttrium powder to create finer oxides. Principles established in steels were used to optimize the beta phase transformation stability for martensite transformation toughening in titanium alloys. The Olson-Cohen kinetic model is calibrated to shear strains in titanium. A frictional work database is established for common alloying

  4. Pure autonomic failure.

    PubMed

    Garland, Emily M; Hooper, William B; Robertson, David

    2013-01-01

    A 1925 report by Bradbury and Eggleston first described patients with extreme orthostatic hypotension and a low, steady heart rate. Evidence accumulated over the next two decades that patients with orthostatic hypotension include those with pure autonomic failure (PAF), characterized by isolated peripheral autonomic dysfunction and decreased norepinephrine synthesis; multiple system atrophy (MSA) with symptoms of a central Parkinson-like syndrome and normal resting plasma norepinephrine; and Parkinson's disease (PD), with lesions in postganglionic noradrenergic neurons and signs of autonomic dysfunction. All three disorders are classified as α-synucleinopathies. Insoluble deposits of α-synuclein are found in glia in MSA, whereas they take the form of neuronal cytoplasmic inclusions called Lewy bodies in PAF and PD. The exact relationship between α-synuclein deposits and the pathology remains undetermined. PAF occurs sporadically, and progresses slowly with a relatively good prognosis. However, it has been proposed that some cases of PAF may develop a central neurodegenerative disorder. Differentiation between PAF, MSA, and PD with autonomic failure can be facilitated by a number of biochemical and functional tests and by imaging studies. Cardiac sympathetic innervation is generally intact in MSA but decreased or absent in Parkinson's disease with autonomic failure and PAF. Treatment of PAF is directed at relieving symptoms with nonpharmacological interventions and with medications producing volume expansion and vasoconstriction. Future studies should focus on determining the factors that lead to central rather than solely peripheral neurodegeneration. PMID:24095130

  5. Underwater wet welding of steel

    SciTech Connect

    Ibarra, S.; Liu, S.; Olson, D.L.

    1995-05-01

    Underwater wet welding is conducted directly in water with the shielded metal arc (SMA) and flux cored arc (FCA) welding processes. Underwater wet welding has been demonstrated as an acceptable repair technique down to 100 meters (325 ft.) in depth, but wet welds have been attempted on carbon steel structures down to 200 meters (650 ft.). The primary purpose of this interpretive report is to document and evaluate current understanding of metallurgical behavior of underwater wet welds so that new welding consumables can be designed and new welding practices can be developed for fabrication and repair of high strength steel structures at greater depths. First the pyrometallurgical and physical metallurgy behaviors of underwater weldments are discussed. Second, modifications of the welding consumables and processes are suggested to enhance the ability to apply wet welding techniques.

  6. Flow Dynamics in Arc Welding

    SciTech Connect

    Lowke, John J.; Tanaka, Manabu

    2008-02-21

    The state of the art for numerical computations has now advanced so that the capability is within sight of calculating weld shapes for any arc current, welding gas, welding material or configuration. Inherent in these calculations is 'flow dynamics' applied to plasma flow in the arc and liquid metal flow in the weld pool. Examples of predictions which are consistent with experiment, are discussed for (1) conventional tungsten inert gas welding, (2) the effect of a fraction of a percent of sulfur in steel, which can increase weld depth by more than a factor of two through changes in the surface tension, (3) the effect of a flux, which can produce increased weld depth due to arc constriction, (4) use of aluminium instead of steel, when the much larger thermal conductivity of aluminium greatly reduces the weld depth and (5) addition of a few percent of hydrogen to argon, which markedly increases weld depth.

  7. Laser weld jig. [Patent application

    DOEpatents

    Van Blarigan, P.; Haupt, D.L.

    1980-12-05

    A system is provided for welding a workpiece along a predetermined weld line that may be of irregular shape, which includes the step of forming a lip on the workpiece to extend parallel to the weld line, and moving the workpiece by engaging the lip between a pair of rotatable members. 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 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 reusable jig forming the lip, and with the jig constructed to detachably hold parts to be welded at a position wherein the weld line of the parts extends parallel to the lip on the jig.

  8. Effect of cathodic polarization on coating doxycycline on titanium surfaces.

    PubMed

    Geißler, Sebastian; Tiainen, Hanna; Haugen, Håvard J

    2016-06-01

    Cathodic polarization has been reported to enhance the ability of titanium based implant materials to interact with biomolecules by forming titanium hydride at the outermost surface layer. Although this hydride layer has recently been suggested to allow the immobilization of the broad spectrum antibiotic doxycycline on titanium surfaces, the involvement of hydride in binding the biomolecule onto titanium remains poorly understood. To gain better understanding of the influence this immobilization process has on titanium surfaces, mirror-polished commercially pure titanium surfaces were cathodically polarized in the presence of doxycycline and the modified surfaces were thoroughly characterized using atomic force microscopy, electron microscopy, secondary ion mass spectrometry, and angle-resolved X-ray spectroscopy. We demonstrated that no hydride was created during the polarization process. Doxycycline was found to be attached to an oxide layer that was modified during the electrochemical process. A bacterial assay using bioluminescent Staphylococcus epidermidis Xen43 showed the ability of the coating to reduce bacterial colonization and planktonic bacterial growth. PMID:27040230

  9. The synthesis of titanium carbide-reinforced carbon nanofibers

    NASA Astrophysics Data System (ADS)

    Zhu, Pinwen; Hong, Youliang; Liu, Bingbing; Zou, Guangtian

    2009-06-01

    Tailoring hard materials into nanoscale building blocks can greatly extend the applications of hard materials and, at the same time, also represents a significant challenge in the field of nanoscale science. This work reports a novel process for the preparation of carbon-based one-dimensional hard nanomaterials. The titanium carbide-carbon composite nanofibers with an average diameter of 90 nm are prepared by an electrospinning technique and a high temperature pyrolysis process. A composite solution containing polyacrylonitrile and titanium sources is first electrospun into the composite nanofibers, which are subsequently pyrolyzed to produce the desired products. The x-ray diffraction pattern and transmission electron microscopy results show that the main phase of the as-synthesized nanofibers is titanium carbide. The Raman analyses show that the composite nanofibers have low graphite clusters in comparison with the pure carbon nanofibers originating from the electrospun polyacrylonitrile nanofibers. The mechanical property tests demonstrate that the titanium carbide-carbon nanofiber membranes have four times higher tensile strength than the carbon nanofiber membranes, and the Young's modulus of the titanium carbide-carbon nanofiber membranes increases in direct proportion to the titanium quantity.

  10. Properties of titanium-alloyed DLC layers for medical applications

    PubMed Central

    Joska, Ludek; Fojt, Jaroslav; Cvrcek, Ladislav; Brezina, Vitezslav

    2014-01-01

    DLC-type layers offer a good potential for application in medicine, due to their excellent tribological properties, chemical resistance, and bio-inert character. The presented study has verified the possibility of alloying DLC layers with titanium, with coatings containing three levels of titanium concentration prepared. Titanium was present on the surface mainly in the form of oxides. Its increasing concentration led to increased presence of titanium carbide as well. The behavior of the studied systems was stable during exposure in a physiological saline solution. Electrochemical impedance spectra practically did not change with time. Alloying, however, changed the electrochemical behavior of coated systems in a significant way: from inert surface mediating only exchange reactions of the environment in the case of unalloyed DLC layers to a response corresponding rather to a passive surface in the case of alloyed specimens. The effect of DLC layers alloying with titanium was tested by the interaction with a simulated body fluid, during which precipitation of a compound containing calcium and phosphorus - basic components of the bone apatite - occurred on all doped specimens, in contrast to pure DLC. The results of the specimens' surface colonization with cells test proved the positive effect of titanium in the case of specimens with a medium and highest content of this element. PMID:25093457

  11. Weld failure detection

    DOEpatents

    Pennell, William E.; Sutton, Jr., Harry G.

    1981-01-01

    Method and apparatus for detecting failure in a welded connection, particrly applicable to not readily accessible welds such as those joining components within the reactor vessel of a nuclear reactor system. A preselected tag gas is sealed within a chamber which extends through selected portions of the base metal and weld deposit. In the event of a failure, such as development of a crack extending from the chamber to an outer surface, the tag gas is released. The environment about the welded area is directed to an analyzer which, in the event of presence of the tag gas, evidences the failure. A trigger gas can be included with the tag gas to actuate the analyzer.

  12. Laser welding of venotomies.

    PubMed

    White, R A; Abergel, R P; Klein, S R; Kopchok, G; Dwyer, R M; Uitto, J

    1986-08-01

    We investigated the histologic and biochemical effects of carbon dioxide and neodymium (Nd)-YAG laser welding on the healing of venotomies. Ten canine femoral venotomies 2 cm in length were approximated and welded with 10 600-nm wavelength, 1-W power over 20 to 25 s for CO2 laser, and 1060-nm wavelength, 1-W power over 30 to 40 s for Nd-YAG laser. On removal at one to three weeks, all veins (4/4 welded by CO2 and 6/6 by Nd-YAG) were patent without hematomas. Histologic and biochemical analyses of the venous tissues demonstrated active healing at the venotomy sites. We conclude that the CO2 and Nd-YAG lasers can be used successfully to weld venotomies and may provide an alternative to conventional suture techniques for repair of vascular lesions. PMID:3089196

  13. Friction stir welding tool

    DOEpatents

    Tolle; Charles R. , Clark; Denis E. , Barnes; Timothy A.

    2008-04-15

    A friction stir welding tool is described and which includes a shank portion; a shoulder portion which is releasably engageable with the shank portion; and a pin which is releasably engageable with the shoulder portion.

  14. Electron Beam Welding of a Depleted Uranium Alloy to Niobium Using a Calibrated Electron Beam Power Density Distribution

    SciTech Connect

    Elmer, J.W.; Teruya, A.T.; Terrill, P.E.

    2000-08-21

    Electron beam test welds were made joining flat plates of commercially pure niobium to a uranium-6wt%Nb (binary) alloy. The welding parameters and joint design were specifically developed to minimize mixing of the niobium with the U-6%Nb alloy. A Modified Faraday Cup (MFC) technique using computer-assisted tomography was employed to determine the precise power distribution of the electron beam so that the welding parameters could be directly transferred to other welding machines and/or to other facilities.

  15. Friction stir weld tools

    NASA Technical Reports Server (NTRS)

    Carter, Robert W. (Inventor); Payton, Lewis N. (Inventor)

    2007-01-01

    A friction stir weld tool sleeve is supported by an underlying support pin. The pin material is preferably selected for toughness and fracture characteristics. The pin sleeve preferably has a geometry which employs the use of an interrupted thread, a plurality of flutes and/or eccentric path to provide greater flow through. Paddles have been found to assist in imparting friction and directing plastic metal during the welding process.

  16. Weld braze technique

    DOEpatents

    Kanne, Jr., William R.; Kelker, Jr., John W.; Alexander, Robert J.

    1982-01-01

    High-strength metal joints are formed by a combined weld-braze technique. A hollow cylindrical metal member is forced into an undersized counterbore in another metal member with a suitable braze metal disposed along the bottom of the counterbore. Force and current applied to the members in an evacuated chamber results in the concurrent formation of the weld along the sides of the counterbore and a braze along the bottom of the counterbore in one continuous operation.

  17. Friction Stir Weld Tools

    NASA Technical Reports Server (NTRS)

    Carter, Robert W. (Inventor); Payton, Lewis N. (Inventor)

    2007-01-01

    A friction stir weld tool sleeve is supported by an underlying support pin. The pin material is preferably selected for toughness and fracture characteristics. The pin sleeve preferably has a geometry which employs the use of an interrupted thread, a plurality of flutes and/or eccentric path to provide greater flow through. Paddles have been found to assist in imparting friction and directing plastic metal during the welding process.

  18. 46 CFR 154.660 - Pipe welding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Pipe welding. 154.660 Section 154.660 Shipping COAST... § 154.660 Pipe welding. (a) Pipe welding must meet Part 57 of this chapter. (b) Longitudinal butt welds... butt welds must meet the following: (1) Butt welds of pipes made from carbon, carbon manganese, or...

  19. Concurrent ultrasonic weld evaluation system

    DOEpatents

    Hood, Donald W.; Johnson, John A.; Smartt, Herschel B.

    1987-01-01

    A system for concurrent, non-destructive evaluation of partially completed welds for use in conjunction with an automated welder. The system utilizes real time, automated ultrasonic inspection of a welding operation as the welds are being made by providing a transducer which follows a short distance behind the welding head. Reflected ultrasonic signals are analyzed utilizing computer based digital pattern recognition techniques to discriminate between good and flawed welds on a pass by pass basis. The system also distinguishes between types of weld flaws.

  20. EB welding of launch vehicles

    NASA Astrophysics Data System (ADS)

    Szabo, Attila

    While large structural components can be electron beam (EB) welded, equipment and operating costs increase with the requisite vacuum chamber's size. Attention is presently given to cost-effective ways of EB welding launch-vehicle assemblies without compromise of weld quality in such alloys as 2219, 2090, Weldalite, and HP9-4-30/20. Weld strengths at both room and cryogenic temperatures that were 50 percent higher than those obtainable for such materials with arc welding have been demonstrated. Fracture toughnesses were also 40-50 percent higher than arc-welded values. Attention is given to EB joint fit-up allowables for 2219-T87 Al alloy.

  1. Concurrent ultrasonic weld evaluation system

    DOEpatents

    Hood, D.W.; Johnson, J.A.; Smartt, H.B.

    1985-09-04

    A system for concurrent, non-destructive evaluation of partially completed welds for use in conjunction with an automated welder. The system utilizes real time, automated ultrasonic inspection of a welding operation as the welds are being made by providing a transducer which follows a short distance behind the welding head. Reflected ultrasonic signals are analyzed utilizing computer based digital pattern recognition techniques to discriminate between good and flawed welds on a pass by pass basis. The system also distinguishes between types of weld flaws.

  2. Concurrent ultrasonic weld evaluation system

    DOEpatents

    Hood, D.W.; Johnson, J.A.; Smartt, H.B.

    1987-12-15

    A system for concurrent, non-destructive evaluation of partially completed welds for use in conjunction with an automated welder is disclosed. The system utilizes real time, automated ultrasonic inspection of a welding operation as the welds are being made by providing a transducer which follows a short distance behind the welding head. Reflected ultrasonic signals are analyzed utilizing computer based digital pattern recognition techniques to discriminate between good and flawed welds on a pass by pass basis. The system also distinguishes between types of weld flaws. 5 figs.

  3. Pure optical photoacoustic microscopy

    PubMed Central

    Xie, Zhixing; Chen, Sung-Liang; Ling, Tao; Guo, L. Jay; Carson, Paul L.; Wang, Xueding

    2011-01-01

    The concept of pure optical photoacoustic microscopy(POPAM) was proposed based on optical rastering of a focused excitation beam and optically sensing the photoacoustic signal using a microring resonator fabricated by a nanoimprinting technique. After the refinements of the microring’s working wavelength and in the resonator structure and mold fabrication, an ultrahigh Q factor of 3.0×105 was achieved which provided high sensitivity with a noise equivalent detectable pressure(NEDP) value of 29Pa. This NEDP is much lower than the hundreds of Pascals achieved with existing optical resonant structures such as etalons, fiber gratings and dielectric multilayer interference filters available for acoustic measurement. The featured high sensitivity allowed the microring resonator to detect the weak photoacoustic signals from micro- or submicroscale objects. The inherent superbroad bandwidth of the optical microring resonator combined with an optically focused scanning beam provided POPAM with high resolution in the axial as well as both lateral directions while the axial resolution of conventional photoacoustic microscopy (PAM) suffers from the limited bandwidth of PZT detectors. Furthermore, the broadband microring resonator showed similar sensitivity to that of our most sensitive PZT detector. The current POPAM system provides a lateral resolution of 5 μm and an axial resolution of 8 μm, comparable to that achieved by optical microscopy while presenting the unique contrast of optical absorption and functional information complementing other optical modalities. The 3D structure of microvasculature, including capillary networks, and even individual red blood cells have been discerned successfully in the proof-of-concept experiments on mouse bladders ex vivo and mouse ears in vivo. The potential of approximately GHz bandwidth of the microring resonator also might allow much higher resolution than shown here in microscopy of optical absorption and acoustic propagation

  4. Study on titanium foil coated with partial reduction titanium dioxide as bipolar lead-acid battery's substrate

    NASA Astrophysics Data System (ADS)

    Lang, Xiaoshi; Wang, Dianlong; Tang, Shenzhi; Zhu, Junsheng; Guo, Chenfeng

    2014-12-01

    Pure titanium foil cannot be directly as the substrate for the bipolar lead-acid battery due to its surface oxidized into titanium dioxide in the cell cycle. The poor electronic conductivity of titanium dioxide will increase substrate's ohmic resistance and can affect the cell's electrochemical performances. In this paper, titanium foil's surface is coated with a lay of partial reduction titanium dioxide (TiO2-x) which has excellent chemical stability and high electronic conductivity by means of sol-gel method. Through XRD, SEM and four-probe test, it shows that the modified titanium's surface has the most superior crystal structure and morphology and the highest electronic conductivity in the sintering temperature of 800 °C. We subsequently assemble bipolar lead-acid batteries with Ti coated by TiO2-x as the substrate material. The batteries are discovered that when charged and discharged in 3.5 V-4.84 V at 0.5C the voltage between the charge and discharge voltage platform is 0.3 V, and the initial discharge specific capacity can reach 80 mAh g-1. When the current rate is up to 1C and 2C, the initial discharge specific capacity is 70 mAh g-1and 60 mAh g-1. After 100 cycles, the initial specific capacity only decreases 12.5%.

  5. Automatic Welding System

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Robotic welding has been of interest to industrial firms because it offers higher productivity at lower cost than manual welding. There are some systems with automated arc guidance available, but they have disadvantages, such as limitations on types of materials or types of seams that can be welded; susceptibility to stray electrical signals; restricted field of view; or tendency to contaminate the weld seam. Wanting to overcome these disadvantages, Marshall Space Flight Center, aided by Hayes International Corporation, developed system that uses closed-circuit TV signals for automatic guidance of the welding torch. NASA granted license to Combined Technologies, Inc. for commercial application of the technology. They developed a refined and improved arc guidance system. CTI in turn, licensed the Merrick Corporation, also of Nashville, for marketing and manufacturing of the new system, called the CT2 Optical Trucker. CT2 is a non-contracting system that offers adaptability to broader range of welding jobs and provides greater reliability in high speed operation. It is extremely accurate and can travel at high speed of up to 150 inches per minute.

  6. Weld radiograph enigmas

    NASA Technical Reports Server (NTRS)

    Jemian, Wartan A.

    1986-01-01

    Weld radiograph enigmas are features observed on X-ray radiographs of welds. Some of these features resemble indications of weld defects, although their origin is different. Since they are not understood, they are a source of concern. There is a need to identify their causes and especially to measure their effect on weld mechanical properties. A method is proposed whereby the enigmas can be evaluated and rated, in relation to the full spectrum of weld radiograph indications. Thie method involves a signature and a magnitude that can be used as a quantitive parameter. The signature is generated as the diference between the microdensitometer trace across the radiograph and the computed film intensity derived from a thickness scan along the corresponding region of the sample. The magnitude is the measured difference in intensity between the peak and base line values of the signature. The procedure is demonstated by comparing traces across radiographs of a weld sample before and after the introduction of a hole and by a system based on a MacIntosh mouse used for surface profiling.

  7. Numerical Study for Gta Weld Shape Variation by Coupling Welding Arc and Weld Pool

    NASA Astrophysics Data System (ADS)

    Dong, Wenchao; Lu, Shanping; Li, Dianzhong; Li, Yiyi

    A numerical modeling of the welding arc and weld pool is studied for moving GTA welding to investigate the effect of the surface active element oxygen and the plasma drag force on the weld shape. Based on the 2D axisymmetric numerical modeling of the argon arc, the heat flux, current density and plasma drag force are obtained under different welding currents. Numerical calculations to the weld pool development are carried out for moving GTA welding on SUS304 stainless steel with different oxygen contents 30 ppm and 220 ppm, respectively. The results show that the plasma drag force is another dominating driving force affecting the liquid pool flow pattern, except for the Marangoni force. The different welding currents will change the temperature distribution and plasma drag force on the pool surface, and affect the strength of Marangoni convection and the weld shape. The weld D/W ratio initially increases, followed by a constant value around 0.5 with the increasing welding current under high oxygen content. The weld D/W ratio under the low oxygen content slightly decreases with the increasing welding current. The predicted weld shape by simulation agrees well with experimental results.

  8. Fabrication and evaluation of superplastically formed/weld-brazed corrugated compression panels with beaded webs

    NASA Technical Reports Server (NTRS)

    Royster, D. M.; Davis, R. C.; Shinn, J. M., Jr.; Bales, T. T.; Wiant, H. R.

    1985-01-01

    A study was made to investigate the feasibility of superplastically forming corrugated panels with beaded webs and to demonstrate the structural integrity of these panels by testing. The test panels in the study consist of superplastically formed titanium alloy Ti-6Al-4V half-hat elements that are joined by weld-brazing to titanium alloy Ti-6Al-4V caps to form either single-corrugation compression panels or multiple-corrugation compression panels. Stretching and subsequent thinning of the titanium sheet during superplastic forming is reduced by approximately 35 percent with a shallow half-hat die concept instead of a deep die concept and results in a more uniform thickness across the beaded webs. The complete panels are tested in end compression at room temperature and the results compared with analysis. The heavily loaded panels failed at loads approaching the yield strength of the titanium material. At maximum load, the caps wrinkled locally accompanied with separation of the weld-braze joint in the wrinkle. None of the panels tested, however, failed catastrophically in the weld-braze joint. Experimental test results are in good agreement with structural analysis of the panels.

  9. High-temperature oxidation of titanium silicide coatings on titanium

    SciTech Connect

    Abba, A.; Caillet, M.; Galerie, A.

    1982-02-01

    Coatings of Ti/sub 5/Si/sub 3/ on titanium have been prepared by means of decomposition of silane SiH/sub 4/ on heated titanium ribbons. Oxidation of the coated titanium specimens was much slower than that of the noncoated ones. Gravimetric and morphological experiments allowed to propose a mechanism describing the oxidation process.

  10. Low-Temperature Forming of Beta Titanium Alloys

    NASA Technical Reports Server (NTRS)

    Kaneko, R. S.; Woods, C. A.

    1983-01-01

    Low cost methods for titanium structural fabrication using advanced cold-formable beta alloys were investigated for application in a Mach 2.7 supersonic cruise vehicle. This work focuses on improving processing and structural efficiencies as compared with standard hot formed and riveted construction of alpha-beta alloy sheet structure. Mechanical property data and manufacturing parameters were developed for cold forming, brazing, welding, and processing Ti-15V-3Cr-3Sn-3Al sheet, and Ti-3Al-8V-6Cr-4Zr on a more limited basis. Cost and structural benefits were assessed through the fabrication and evaluation of large structural panels. The feasibility of increasing structural efficiency of beta titanium structure by selective reinforcement with metal matrix composite was also explored.

  11. Titanium Cold Spray Coatings

    NASA Astrophysics Data System (ADS)

    Ajaja, Jihane; Goldbaum, Dina; Chromik, Richard; Yue, Stephen; Rezaeian, Ahmad; Wong, Wilson; Irissou, Eric; Legoux, Jean-Gabriel

    Titanium Cold Spray Coatings Cold Spray is an emerging technology used for the deposition of coatings for many industries including aerospace. This technique allows the deposition of metallic materials at low temper-atures below their melting point. The aim of this research was to develop a test technique that can measure the degree to which a cold spray coating achieves mechanical properties similar to a traditional bulk material. Vickers hardness testing and nanoindentation were used as micro-and nano-scale measurement techniques to characterize the mechanical properties of titanium coatings, deposited at different deposition conditions, and bulk Ti. The mechanical properties of bulk titanium and titanium coatings were measured over a range of length scales, with the indentation size effect examined with Meyer's law. Hardness measurements are shown to be affected by material porosity, microstructure and coating particle bonding mechanism. Hard-ness measurements showed that Ti coatings deposited at higher gas pressures and temperatures demonstrate an indentation load response similar to bulk Ti. Key words: titanium, cold spray, Vickers hardness, nanoindentation, indentation size effect, microstructure, mechanical properties

  12. Ultrasonic NDE of titanium diffusion bonds using signal phase

    NASA Astrophysics Data System (ADS)

    Escobar-Ruiz, E.; Cawley, P.; Nagy, P. B.; Collison, I.; Wright, D.

    2013-01-01

    Diffusion bonding is a highly advantageous solid-state welding method. However, its full exploitation in titanium components is currently limited by a lack of robust NDE techniques capable of detecting anything but gross bond-line defects. A novel ultrasonic technique has been developed to address this lack of capability. This technique, based on the ultrasonic signal phase, has been demonstrated in a `single-sided' scenario where only one side of the diffusion bond was accessible. Samples with differing degrees of bond quality were evaluated, and excellent agreement was found between the single-sided and double-sided experiments.

  13. Fluid Flow Phenomena during Welding

    SciTech Connect

    Zhang, Wei

    2011-01-01

    MOLTEN WELD POOLS are dynamic. Liquid in the weld pool in acted on by several strong forces, which can result in high-velocity fluid motion. Fluid flow velocities exceeding 1 m/s (3.3 ft/s) have been observed in gas tungsten arc (GTA) welds under ordinary welding conditions, and higher velocities have been measured in submerged arc welds. Fluid flow is important because it affects weld shape and is related to the formation of a variety of weld defects. Moving liquid transports heat and often dominates heat transport in the weld pool. Because heat transport by mass flow depends on the direction and speed of fluid motion, weld pool shape can differ dramatically from that predicted by conductive heat flow. Temperature gradients are also altered by fluid flow, which can affect weld microstructure. A number of defects in GTA welds have been attributed to fluid flow or changes in fluid flow, including lack of penetration, top bead roughness, humped beads, finger penetration, and undercutting. Instabilities in the liquid film around the keyhole in electron beam and laser welds are responsible for the uneven penetration (spiking) characteristic of these types of welds.

  14. Titanium oxidation by rf inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Valencia-Alvarado, R.; de la Piedad-Beneitez, A.; López-Callejas, R.; Barocio, S. R.; Mercado-Cabrera, A.; Peña-Eguiluz, R.; Muñoz-Castro, A. E.; Rodríguez-Méndez, B. G.; de la Rosa-Vázquez, J. M.

    2014-05-01

    The development of titanium dioxide (TiO2) films in the rutile and anatase phases is reported. The films have been obtained from an implantation/diffusion and sputtering process of commercially pure titanium targets, carried out in up to 500 W plasmas. The experimental outcome is of particular interest, in the case of anatase, for atmospheric pollution degradation by photocatalysis and, as to the rutile phase, for the production of biomaterials required by prosthesis and implants. The reactor employed consists in a cylindrical pyrex-like glass vessel inductively coupled to a 13.56 MHz RF source. The process takes place at a 5×10-2 mbar pressure with the target samples being biased from 0 to -3000 V DC. The anatase phase films were obtained from sputtering the titanium targets over glass and silicon electrically floated substrates placed 2 cm away from the target. The rutile phase was obtained by implantation/diffusion on targets at about 700 °C. The plasma was developed from a 4:1 argon/oxygen mixture for ~5 hour processing periods. The target temperature was controlled by means of the bias voltage and the plasma source power. The obtained anatase phases did not require annealing after the plasma oxidation process. The characterization of the film samples was conducted by means of x-ray diffraction, scanning electron microscopy, x-ray photoelectron spectroscopy and Raman spectroscopy.

  15. METHOD OF OBTAINING AN IMPROVED WELD IN INERT ARC WELDING

    DOEpatents

    Correy, T.B.

    1962-12-11

    A method is reported for inert arc welding. An a-c welding current is applied to the workpiece and welding electrode such that the positive portion of each cycle thereof, with the electrode positive, has only sufficient energy to clean the surface of the workpiece and the negative portion of each cycle thereof, with the electrode negative, contains the energy required to weld. (AEC)

  16. Effect of Ti-containing inclusions on the nucleation of acicular ferrite and mechanical properties of multipass weld metals.

    PubMed

    Fattahi, M; Nabhani, N; Hosseini, M; Arabian, N; Rahimi, E

    2013-02-01

    In the present study, the influence of Ti-containing inclusions on the development of acicular ferrite microstructure and mechanical properties in the multipass weld metals has been studied. Shielded metal arc weld deposits were prepared by varying titanium content in the range of 0.003-0.021%. The variation in the titanium content was obtained by the addition of different amounts of titanium oxide nanoparticles to the electrode coating. The dispersion of titanium oxide nanoparticles, composition of inclusions, microstructural analysis, tensile properties and Charpy impact toughness were evaluated. As the amount of Ti-containing inclusions in the weld metal was increased, the microstructure of the weld metal was changed from the grain boundary allotriomorphic ferrite structure to acicular ferrite with the intragranular nucleation of ferrite on the Ti-containing inclusions, and the mechanical properties were improved. This improvement is attributable to the increased percentage of acicular ferrite due to the uniform dispersion of Ti-containing inclusions and the pinning force of oxide nanoparticles against the growth of allotriomorphic ferrite and Widmanstätten ferrite from the austenite grain boundaries. PMID:23238108

  17. Laser beam interactions with vapor plumes during Nd:YAG laser welding on aluminum

    NASA Astrophysics Data System (ADS)

    Peebles, H. C.; Russo, A. J.; Hadley, G. R.; Akau, R. L.

    Welds produced on pure aluminum targets using pulsed Nd:YAG lasers can be accurately described using a relatively simple conduction mode heat transfer model provided that the fraction of laser energy absorbed is known and the amount of metal vaporized is smalled however at laser fluences commonly used in many production welding schedules significant aluminum vaporization does occur. The possible mechanisms have been identified which could result in laser beam attenuation by the vapor plume.

  18. Analysis of multicomponent evaporation in electron beam melting and refining of titanium alloys

    SciTech Connect

    Powell, A.; Szekely, J.; Pal, U.; Avyle, J. van den; Damkroger, B.

    1997-12-01

    Experimental evidence and a mathematical model are presented to evaluate the effect of beam-scan frequency on composition change in electron-beam melting of titanium alloys. Experiments characterized the evaporation rate of commercially pure (CP) titanium and vapor composition over titanium alloy with up to 6 wt pct aluminum and 4.5 wt pct vanadium, as a function of beam power, scan frequency, and background pressure. These data and thermal mapping of the hearth melt surface are used to estimate activity coefficients of aluminum and vanadium in the hearth. The model describes transient heat transfer in the surface of the melt and provides a means of estimating enhancement of pure titanium evaporation and change in final aluminum composition due to local heating at moderate beam-scan frequencies.

  19. Effect of hydrogen on the mechanical properties of titanium and its alloys

    NASA Technical Reports Server (NTRS)

    Beck, F. H.

    1975-01-01

    Occluded hydrogen resulting from cathodic charging of commercially pure titanium and titanium alloys, Ti-8Al-1Mo-1V and Ti-6Al-4V, was shown to cause embrittlement of the alloys. Embrittlement was a function of the interstitial hydrogen content rather than the amount of precipitated titanium hydride. The effects of hydrogen concentration on the critical strain for plastic instability along pure shear directions was determined for alloys Ti-8Al-1Mo-1V and Ti-5Al-2.5Sn. Hydrogen, in concentrations below that necessary for spontaneous hydride precipitation, increased the strain necessary for instability formation or instability failure. The strain rate sensitivity also increased with increasing hydrogen concentration. The effect of hydrogen on slip and twinning was determined for titanium single crystals. The critical resolved shear stress for prism slip was increased and the critical resolved shear stress for twinning was decreased with increasing hydrogen concentration.

  20. Improved adherence of sputtered titanium carbide coatings on nickel- and titanium-base alloys

    NASA Technical Reports Server (NTRS)

    Wheeler, D. R.; Brainard, W. A.

    1979-01-01

    Rene 41 and Ti-6Al-4V alloys were radio frequency sputter coated with titanium carbide by several techniques in order to determine the most effective. Coatings were evaluated in pin-on-disk tests. Surface analysis by X-ray photoelectron spectroscopy was used to relate adherence to interfacial chemistry. For Rene 41, good coating adherence was obtained when a small amount of acetylene was added to the sputtering plasma. The acetylene carburized the alloy surface and resulted in better bonding to the TiC coating. For Ti-6Al-4V, the best adherence and wear protection was obtained when a pure titanium interlayer was used between the coating and the alloy. The interlayer is thought to prevent the formation of a brittle, fracture-prone, aluminum oxide layer.