Topics: DTIC Archive, Davydov, Yu P, FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OH, *AUSTENITE, *HEAT...
An in-depth material characterization of Electron Beam Melted (EBM) Ti-6Al-4V material has been completed. Hot Isostatic Pressing (HIP) was utilized to close porosity from fabrication and also served as a material heat treatment to obtain the desired microstructure. The changes in the microstructure and chemistry from the powder to pre-HIP and post-HIP material have been analyzed. Computed tomography (CT) scans indicated porosity closure during HIP and high-density inclusions scattered...
Topics: NASA Technical Reports Server (NTRS), TITANIUM ALLOYS, VANADIUM ALLOYS, ELECTRON BEAMS, HOT...
Adhesive bonding offers many advantages over mechanical fastening, but requires robust materials and processing methodologies before it can be incorporated in primary structures for aerospace applications. Surface preparation is widely recognized as one of the key steps to producing robust and predictable bonds. This report documents an ongoing investigation of a surface preparation technique based on Nd:YAG laser ablation as a replacement for the chemical etch and/or abrasive processes...
Topics: NASA Technical Reports Server (NTRS), ADHESIVE BONDING, AEROSPACE ENGINEERING, SURFACE TREATMENT,...
Grain refinement can significantly improve the mechanical properties of freeform-fabricated Ti-6Al-4V alloy, promoting increased strength and enhanced isotropy compared with coarser grained material. Large beta-grains can lead to a segregated microstructure, in regard to both alpha-phase morphology and alpha-lath orientation. Beam modulation, which has been used in conventional fusion welding to promote grain refinement, is explored in this study for use in additive manufacturing processes...
Topics: NASA Technical Reports Server (NTRS), ALUMINUM ALLOYS, TITANIUM ALLOYS, GRAIN SIZE, MECHANICAL...
This investigation was prompted by results of a qualification test of a mechanism to be used for the James Webb Space Telescope. Post-test inspections of the qualification test article revealed some loose wear debris and wear of the steel rollers and the mating Ti6Al4V surfaces. An engineering assessment of the design and observations from the tested qualification unit suggested that roller misalignment was a controlling factor. The wear phenomena were investigated using dedicated laboratory...
Topics: NASA Technical Reports Server (NTRS), ALUMINUM ALLOYS, ROLLERS, STEELS, TITANIUM ALLOYS, VANADIUM...
Adhesive bonding offers many advantages over mechanical fastening, but requires certification before it can be incorporated in primary structures for commercial aviation without disbond-arrestment features or redundant load paths. Surface preparation is widely recognized as the key step to producing robust and predictable bonds. Laser ablation imparts both topographical and chemical changes to a surface which can lead to increased bond durability. A laser based process provides an alternative...
Topics: NASA Technical Reports Server (NTRS), ALUMINUM ALLOYS, LASER ABLATION, SURFACE TREATMENT, TITANIUM...
Vanadium dioxide (VO2) undergoes a sharp metal-insulator transition (MIT) in the vicinity of room temperature and there is great interest in exploiting this effect in novel electronic and photonic devices. We have measured the work function of VO2 thin films across the phase transition for the first time using variable temperature Kelvin force microscopy (KFM). The work function of VO2 is estimated to be 5.15 eV in the insulating phase and increases by approximately 0.15 eV across the MIT. We...
Topics: DTIC Archive, HARVARD UNIV CAMBRIDGE MA SCHOOL OF ENGINEERING AND APPLIED SCIENCES, *PHASE...
In April 2008, NASA-STD-5009 established a requirement that only sensitivity level 4 penetrants are acceptable for NASA Standard Level liquid penetrant inspections. Having NASA contractors change existing processes or perform demonstration tests to certify sensitivity level 3 penetrants posed a potentially huge cost to the Agency. This study was conducted to directly compare the probability of detection (POD) of sensitivity level 3 and level 4 penetrants using both Method A and Method D...
Topics: NASA Technical Reports Server (NTRS), CRACKS, DETECTION, FLUORESCENCE, PENETRANTS, SENSITIVITY,...
Adhesively bonded structures are potentially lighter in weight than mechanically fastened ones, but existing surface treatments are often considered unreliable. Two main problems in achieving reproducible and durable adhesive bonds are surface contamination and variability in standard surface preparation techniques. In this work three surface pretreatments were compared: laser etching with and without grit blasting and conventional Pasa-Jell treatment. Ti-6Al-4V surfaces were characterized by...
Topics: NASA Technical Reports Server (NTRS), ADHESIVE BONDING, ALUMINUM ALLOYS, TITANIUM ALLOYS, VANADIUM...
The low-temperature superplastic flow behavior of two lots of Ti-6Al-4V sheet with an ultrafine microstructure was modeled. One lot (Sheet A) had an equiaxed-alpha starting microstructure; the flow stress/flow hardening exhibited by this material was explained on the basis of the Bird-Mukherjee-Dorn constitutive equation. The other material (Sheet B), having a mixed equiaxed- and remnant-lamellar alpha microstructure, underwent flow softening, flow hardening, or steady-state flow depending on...
Topics: DTIC Archive, AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING...
The critical resolved shear stresses and flow curves for the seven possible slip systems in Ti-6Al-4V with a lamellar microstructure were determined via high temperature uniaxial compression testing. For this purpose, samples with a rectangular cross section were cut from single colonies grown using a float-zone technique and then tested at 815 degrees C. Each sample was oriented for single slip along one of seven different slip systems in the alpha phase; i.e., one of the three 1120{1010}...
Topics: DTIC Archive, AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING...
The microstructural evolution following metal cutting was investigated within the metal chips of Ti-6Al-4V. Metal cutting was used to impose a high strain rate on the order of approx.10(exp 5)/s within the primary shear zone as the metal was removed from the workpiece. The initial microstructure of the parent material (PM) was composed of a bi-modal microstructure with coarse prior grains and equiaxed primary located at the boundaries. After metal cutting, the microstructure of the metal chips...
Topics: NASA Technical Reports Server (NTRS), ALUMINUM ALLOYS, TITANIUM ALLOYS, VANADIUM ALLOYS, STRAIN...
Friction stir welding (FSWing), a solid state joining technique, uses a non-consumable rotating pin tool to thermomechanically join materials. Heating of the weldment caused by friction and deformation is a function of the interaction between the pin tool and the work piece. Therefore, the geometry of the pin tool is in part responsible for the resulting microstructure and mechanical properties. In this study microwave sintered tungsten carbide (WC) pin tools with tapers and flats were used to...
Topics: NASA Technical Reports Server (NTRS), FRICTION STIR WELDING, TITANIUM ALLOYS, TUNGSTEN CARBIDES,...
A systematic study of the effects of stress ratio on small fatigue crack growth in Ti-6Al-4V was conducted. Cylindrical fatigue specimens were tested axially at room temperature under a maximum stress of 690 MPa and with stress ratios (R) of 0.5, 0.1, and -1. Tests were periodically interrupted and a standard replication technique was used to monitor the growth of cracks artificially initiated from 30 to 40 micrometer micro-notches, which were milled into the specimen surface with a focused ion...
Topics: DTIC Archive, AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING...
A wide range of Metal Additive Manufacturing (MAM) technologies are becoming available. One of the challenges in using new technologies for aerospace systems is demonstrating that the process and system has the ability to manufacture components that meet the high quality requirements on a statistically significant basis. The widest-used system for small to medium sized components is the ARCAM system manufactured in Gothenburg, Sweden. This system features a 4kW electron-beam gun, and has a...
Topics: NASA Technical Reports Server (NTRS), ADDITIVES, MANUFACTURING, TITANIUM ALLOYS, VANADIUM ALLOYS,...
Results are presented for a program to determine the near-threshold fatigue crack growth behavior appropriate for metallic rotorcraft alloys. Four alloys, all commonly used in the manufacture of rotorcraft, were selected for study: Aluminum alloy 7050, 4340 steel, AZ91E Magnesium, and Titanium alloy Ti-6Al-4V (beta-STOA). The Federal Aviation Administration (FAA) sponsored this research to advance efforts to incorporate damage tolerance design and analysis as requirements for rotorcraft...
Topics: NASA Technical Reports Server (NTRS), CRACK PROPAGATION, FATIGUE (MATERIALS), ROTARY WING AIRCRAFT,...
This research in support of the Air Force Research Laboratory Materials and Manufacturing Directorate was conducted at Wright-Patterson AFB, Ohio from 3 November 2005 through 31 January 2008. This task developed constitutive models for alpha/beta titanium alloys with colony-alpha microstructure and validated texture prediction models for plate rolling. A method for separating the textures of primary alpha [alpha(sub p] and secondary alpha [alpha(sub s)] in alpha/beta titanium alloys with a...
Topics: DTIC Archive, UNIVERSAL TECHNOLOGY CORP DAYTON OH, *MICROSTRUCTURE, *HOT WORKING, *TITANIUM ALLOYS,...
It was demonstrated by way of experiment that Composite Over-wrapped Pressure Vessel (COPV) Ti-6Al-4V liner material can sustain the expected service loads and cycles. The experiments were performed as part of investigations on the residual life of COPV tanks being used in Space Shuttle Orbiters. Measured properties included tensile strength, compressive strength, reversed loading cycles to simulate liner proof strains, and cyclic fatigue loading to demonstrate the ability to sustain 1000...
Topics: NASA Technical Reports Server (NTRS), FRACTURE STRENGTH, FATIGUE (MATERIALS), MODULUS OF...
The objective of this work was to evaluate life prediction methodologies involving fretting fatigue of turbine engine materials with advanced surface treatments. Fretting fatigue tests were performed on Ti-6Al-4V dovetail specimens with and without advanced surface treatments. These tests were representative of the conditions found in a turbine engine blade to disk attachment. Laser shock processing and low plasticity burnishing have been shown to produce deep compressive residual stresses with...
Topics: DTIC Archive, AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING...
This communication describes the results of spectrum fatigue loading experiments conducted on cast+HIT Ti-6Al-4V. the purpose of the experiments is to elucidate the nature of the faceted crack growth that occurs at low values of delta-K in titanium alloys and also other alloys. The results clearly show that thousands of load cycles are required for the crack to grow across a single facet. The confusing terminology relating to low delta-K fatigue fracture topography is reviewed and the term low...
Topics: DTIC Archive, AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING...
The wear behavior of low-cost, lightweight 10-wt% TiC-particulate-reinforced Ti-6Al-4V matrix composite (TiC/Ti- 6Al-4V) was examined under fretting at 296, 423, and 523 K in air. Bare 10-wt% TiC/Ti-6Al-4V hemispherical pins were used in contact with dispersed multiwalled carbon nanotubes (MWNTs), magnetron-sputtered diamondlike carbon/chromium (DLC/Cr), magnetron-sputtered graphite-like carbon/chromium (GLC/Cr), and magnetron-sputtered molybdenum disulphide/titanium (MoS2/Ti) deposited on...
Topics: NASA Technical Reports Server (NTRS), LOW COST, TITANIUM CARBIDES, VANADIUM ALLOYS, TRIBOLOGY,...
Laser Engineered Net Shaping (LENS) depositions with Ti-6Al-4V gas-atomized powder were accomplished at five different temperatures, ranging from 30 to 400 C, imposed on the base plate. These base plate temperatures were employed in an effort to relieve stresses which develop during the deposition. Warpage of the base plate was monitored. Only a slight decline in warpage was observed as the base plate temperature was increased. Results indicate that substrate temperatures closer to the stress...
Topics: NASA Technical Reports Server (NTRS), TITANIUM ALLOYS, VANADIUM ALLOYS, ALUMINUM ALLOYS,...
Manufacturing of structural metal parts directly from computer aided design (CAD) data has been investigated by numerous researchers over the past decade. Researchers at NASA Langley Research Center are developing a new solid freeform fabrication process, electron beam freeform fabrication (EBF3), as a rapid metal deposition process that works efficiently with a variety of weldable alloys. EBF3 deposits of 2219 aluminium and Ti-6Al-4V have exhibited a range of grain morphologies depending upon...
Topics: NASA Technical Reports Server (NTRS), ELECTRON BEAMS, FABRICATION, COST EFFECTIVENESS,...
A study was conducted to evaluate the relative significance of input parameters on Ti- 6Al-4V deposits produced by an electron beam free form fabrication process under development at the NASA Langley Research Center. Five input parameters where chosen (beam voltage, beam current, translation speed, wire feed rate, and beam focus), and a design of experiments (DOE) approach was used to develop a set of 16 experiments to evaluate the relative importance of these parameters on the resulting...
Topics: NASA Technical Reports Server (NTRS), ALUMINUM ALLOYS, MICROSTRUCTURE, TITANIUM ALLOYS, VANADIUM...
Hypervelocity impact tests have been performed on specimens representing metallic thermal protection systems (TPS) developed at NASA Langley Research Center for use on next-generation reusable launch vehicles (RLV). The majority of the specimens tested consists of a foil gauge exterior honeycomb panel, composed of either Inconel 617 or Ti-6Al-4V, backed with 2.0 in. of fibrous insulation and a final Ti-6Al-4V foil layer. Other tested specimens include titanium multi-wall sandwich coupons as...
Topics: NASA Technical Reports Server (NTRS), HYPERVELOCITY IMPACT, IMPACT TESTS, THERMAL PROTECTION,...
This research established a constitutive model for high-temperature deformation of Ti-6Al-4V alloy with a transformed microstructure. It further investigated the morphological (alpha platelet thickness) effect on the high-temperature plastic flow of transformed microstructure in view of inelastic deformation theory.
Topics: DTIC Archive, Kim, Jeoung H, POHANG UNIV OF SCIENCE AND TECHNOLOGY (KOREA) CENTER FOR ADVANCED...
New manufacturing technologies can now produce uniformly distributed particle strengthened titanium matrix composites (TMCs) at lower cost than many types of continuous-fiber composites. The innovative process results in near-final-shape components having a material stiffness up to 26-percent greater than that of components made with conventional titanium materials. This benefit is achieved with no significant increase in the weight of the component. The improved mechanical performance and...
Topics: NASA Technical Reports Server (NTRS), METAL MATRIX COMPOSITES, TITANIUM, PROPULSION, PARTICULATE...
A simple surface treatment process is provided which offers a high performance surface for a variety of applications at low cost. This novel surface treatment, which is particularly useful for Ti-6Al-4V alloys, is achieved by forming oxides on the surface with a two-step chemical process and without mechanical abrasion. First, after solvent degreasing, sulfuric acid is used to generate a fresh titanium surface. Next, an alkaline perborate solution is used to form an oxide on the surface. This...
Topics: NASA Technical Reports Server (NTRS), SURFACE TREATMENT, ADHESIVES, ALUMINUM ALLOYS, CHEMICAL...
This Interim Report covers the contract period from June 17/2002 to Sept. 16/2002 (the first period of three months).The research in this Project is directed toward better understanding of the development of the local plastic fields occurring in mesoscale during spalling of Ti-6A1-4V alloy. The specimens in the form of disks of different thickness and DIA 57.0 mm have been delivered by AMSRL-WM-TA, APG Aberdeen, MD. Later, all specimens have been polished and measured in our Laboratory (LPMM)....
Topics: DTIC Archive, Klepaczko, J R, METZ UNIV (FRANCE) LAB OF PHYSICS AND MECHANICS OF MATERIALS,...
The fretting behavior of Ti-48Al-2Cr-2Nb (y-TiAl) in contact with the nickel-base superalloy 718 was examined in air at temperatures from 296 to 823 K (23 to 550 C). The interfacial adhesive bonds between Ti-48Al-2Cr-2Nb and superalloy 718 were generally stronger than the cohesive bonds within Ti-48Al-2Cr-2Nb. The failed Ti-48Al-2Cr-2Nb debris subsequently transferred to the superalloy 718. In reference experiments conducted with Ti-6Al-4V against superalloy 718 under identical fretting...
Topics: NASA Technical Reports Server (NTRS), ALUMINUM ALLOYS, FRETTING, HEAT RESISTANT ALLOYS, NICKEL...
The Mo-Si-B alloys containing the Mo metal phase in equilibrium with the Mo3Si and Mo5SiB2 intermetallic phases have potential as hot-section materials for jet engines. For high-pressure turbine blade application, the ternary Mo-Si-B compositions exhibit adequate oxidation resistance in the temperature range of 1000 to 1300 deg C, but below 1000 deg C, the oxidation resistance is not good. The present study was undertaken to explore the effect of a number of alloying additions to a ternary...
Topics: DTIC Archive, Mendiratta, M G, UES INC DAYTON OH, *OXIDATION RESISTANCE, *MOLYBDENUM ALLOYS,...
An investigation was conducted to examine the fretting behavior of lambda-TiAl (Ti-48Al-2Cr-2Nb) in contact with a nickel-base superalloy (Inconel 718) in air at temperatures from 23 to 550 C. Fretting wear experiments were conducted with 9.4-mm-diameter hemispherical Inconel (IN) 718 pins in contact with Ti-48Al-2Cr-2Nb flats (and the reverse) at loads from 1 to 40 N and fretting frequencies from 50 to 160 Hz with slip amplitudes from 50 to 200 microns for 1 to 20 million fretting cycles. The...
Topics: NASA Technical Reports Server (NTRS), FRETTING, TITANIUM ALLOYS, ALUMINUM ALLOYS, METAL OXIDES,...
Two series of low cycle fatigue (LCF) test data for two groups of different aircraft gas turbine engine compressor disk geometries were reanalyzed and compared using Weibull statistics. Both groups of disks were manufactured from titanium (Ti-6Al-4V) alloy. A NASA Glenn Research Center developed probabilistic computer code Probable Cause was used to predict disk life and reliability. A material-life factor A was determined for titanium (Ti-6Al-4V) alloy based upon fatigue disk data and...
Topics: NASA Technical Reports Server (NTRS), AIRCRAFT ENGINES, GAS TURBINE ENGINES, PROBABILITY THEORY,...
Improving the tribological functionality of diamondlike carbon (DLC) films--developing, good wear resistance, low friction, and high load-carrying capacity-was the aim of this investigation. Nanocomposite coatings consisting of an amorphous DLC (a-DLC) top layer and a functionally graded titanium-titanium carbon-diamondlike carbon (Ti-Ti(sub x) C(sub y)-DLC) underlayer were produced on AISI 440C stainless steel substrates by the hybrid technique of magnetron sputtering and pulsed-laser...
Topics: NASA Technical Reports Server (NTRS), BRITTLENESS, COATINGS, AMORPHOUS MATERIALS, FRETTING, SLIDING...
From an environment perspective, tungsten is a more desirable material than depleted uranium (DU) for penetrator applications. However, the ballistic performance attained by current tungsten (W) alloys is inferior to DU. Recently, advanced tungsten-metal (W-M) composites have been developed to improve their ballistic penetration, but the corrosion properties are unknown and need to be determined. In this work, the galvanic corrosion behavior of W coupled with several selected metals/alloys was...
Topics: DTIC Archive, Chang, F. C., ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD, *METALS, *ALLOYS,...
The samples of as-received Ti-6%A1-4%V alloys of 3 different oxygen contents ranging from 0.1% to 0.24% have been tested in about 50 shock-wave experiments. In the experiments performed the Hugoniot elastic limit, the spall strength, and the critical diameter for the spall element separation were measured. The peak shock stress was varied from 4 to 75 GPa, the load duration from ^10(exp -7) s to ^10(exp -5) s. The VISAR free-surface velocity measurements show a growth by 20% in the Hugoniot...
Topics: DTIC Archive, Razorenov, Sergey V., ARMY RESEARCH DEVELOPMENT AND STANDARDIZATION GROUP (UNITED...
The goal of this program was to manufacture and burst test small diameter SCS-6/Ti-6Al-4V composite rings for use in the design of an advanced titanium matrix composite (TMC) impeller. The Textron Specialty Metals grooved foil-fiber process was successfully used to make high quality TMC rings. A novel spin test arbor with "soft touch" fingers to retain the TMC ring was designed and manufactured. The design of the arbor took into account its use for cyclic experiments as well as ring...
Topics: NASA Technical Reports Server (NTRS), METAL MATRIX COMPOSITES, TITANIUM ALLOYS, PERFORMANCE...
The goal of this program was to evaluate the low cycle fatigue behavior of an SCS-6/Ti-6Al-4V sub-component under bi-axial loading conditions at 316 C(600 F). A simulated bladed TMC disk was designed having thirty four blades representing the number that would be used in Allied Signal's JTAGG II impeller. The outer diameter of the bladed ring was 254 mm (10.0 inch) and the inner diameter 114.3 mm (4.50 inch). The outer and inner diameter of the composite zone was 177.8 mm (7.00 inch) and 127.O...
Topics: NASA Technical Reports Server (NTRS), DESIGN ANALYSIS, FATIGUE LIFE, STRESS ANALYSIS, TITANIUM...
The static and dynamic fracture toughness, strength, and ductility of various titanium alloys were investigated. The crack propagation toughness and fatigue crack propagation rate under both static and dynamic conditions were also investigated an compared with that of T-6Al-4V at the elevated temperatures. The results showed that sudden decrease in strength, fracture toughness values or the stress intensity factors were noticeable at the elevated temperature of 1123K. The fracture toughness...
Topics: DTIC Archive, Niinomi, Mitsuo, JAPAN TITANIUM SOCIETY TOKYO, *TOUGHNESS, *FRACTURE(MECHANICS),...
Carpenter Hiperco(R) Alloy 50 HS is a recently developed iron-cobalt soft magnetic alloy (48.94% Fe, 48.75% Co, 1.90% V, 0.30% Nb, 0.05% Mn, 0.05% Si, 0.01% C) intended for commercial applications requiring high strength. Its physical, electrical and magnetic properties have not yet been reported over the operating temperatures of interest. This report addresses the resistivity testing of this alloy in .006' thick strip product form (dry hydrogen annealed) and the subsequent conclusions. We...
Topics: DTIC Archive, Simon, Gerard K., WRIGHT LAB WRIGHT-PATTERSON AFB OH MATERIALS DIRECTORATE,...
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Method and apparatus for detecting mechanical vibrations and outputting a signal in response thereto. Art accelerometer package having integral display and control functions is suitable for mounting upon the machinery to be monitored. Display circuitry provides signals to a bar graph display which may be used to monitor machine conditions over a period of time. Control switches may be set which correspond to elements in the bar graph to provide an alert if vibration signals increase in...
Topics: ESTIMATING, MATHEMATICAL MODELS, STRAIN RATE, TEMPERATURE DEPENDENCE, CONSTANTS, SENSITIVITY,...
The X-ray diffractometer system purchased under the grant consists of an X-ray generator and associated equipment for determination of degree of crystallinity, crystallite size and lattice distortion in nano-and micro-crystalline metals and composites; identification of crystalline phases, precision measurement of lattice constants, and determination of phase transformation temperatures in metals, ceramics, and composites at 25-1400 degrees Celsius; determination of grain orientations,...
Topics: DTIC Archive, Sastry, Shankar M., WASHINGTON UNIV ST LOUIS MO, *X RAY DIFFRACTION,...
This paper develops improved stochastic models for the description of a large variety of fatigue crack growth phenomena that occur in components of considerable importance to the functionality and reliability of complex engineering structures. In essence, the models are based on the McGill-Markov and Closure-Lognormal stochastic processes. Not only do these models have the capability of predicting the statistical dispersion of crack growth rates, they also, by incorporating the concept of crack...
Topics: NASA Technical Reports Server (NTRS), CRACK CLOSURE, CRACK PROPAGATION, FAST FOURIER...
Materials specification and distribution of Ti-6A1-4V specimens are presented along with the collated data from those participants that have supplied test results. Crack propagation and strain control low cycle fatigue data are discussed, along with a number of points of clarification regarding test technique. jg
Topics: DTIC Archive, Wilkinson, C., ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT...
A study of the corrosion protection of substrate metals by ion vapor deposited aluminum (IVD Al) coats has been carried out. Corrosion protection by both anodized and unanodized IVD Al coats has been investigated. Base metals included in the study were 2219-T87 Al, 7075-T6 Al, Titanium-6 Al-4 Vanadium (Ti-6Al-4V), 4130 steel, D6AC steel, and 4340 steel. Results reveal that the anodized IVD Al coats provide excellent corrosion protection, but good protection is also achieved by IVD Al coats that...
Topics: NASA Technical Reports Server (NTRS), ALUMINUM, ALUMINUM ALLOYS, ANODIZING, CORROSION PREVENTION,...
In this investigation, flow behavior of Ti-6Al-4V ELI alloy was studied by conducting compression tests over a wide range of temperatures and strain rates. Constitutive relations were determined from the flow behavior, and a dynamic material modeling was conducted on this alloy. Thus, the optimum processing condition in terms of temperature and strain rate was identified. Microstructural changes during high temperature deformation were also characterized.... Ti-6Al-4V ELI, Deformation...
Topics: DTIC Archive, Chaudhury, Prabir, NATIONAL CENTER FOR EXCELLENCE IN METALWORKING TECHNOLOGY...
An investigation was conducted into the friction and wear behavior of both unlubricated and dry-film-lubricated (Tiolube 460) titanium alloy (Ti-6Al-4V) in contact with an uncoated high-nickel-content superalloy (Inconel 718) both in vacuum and in air. The acquisition of friction and wear data for this sliding couple was motivated by the need for input data for the 'antenna stuck ribs model' effort to free Galileo's High Gain Antenna. The results of the investigation indicate that galling...
Topics: NASA Technical Reports Server (NTRS), COEFFICIENT OF FRICTION, GALILEO SPACECRAFT, SLIDING...
A computer model of the frictional heating of metals in an inert environment has been developed. The model incorporates the effects of the heat loss from the samples due to conduction, radiation, and convection to the surroundings. This model allows the measured temperatures to be used to determine the amount of heat produced at the interface during the experiment by the sliding contact of two different metallic samples. The results of the simulation for an experiment run at the NASA White...
Topics: NASA Technical Reports Server (NTRS), CONVECTION, COOLING, FRICTION FACTOR, HEAT TRANSFER, HEATING,...
The damage mechanisms of a laminated, continuous SiC fiber reinforced Ti-15V-3Cr-3Al-3Sn (Ti-15-3) composite were investigated. Specimens consisting of unidirectional as well as cross-ply laminates were pulled in tension to failure at room temperature and 427 C and subsequently examined metallographically. Selected specimens were interrupted at various strain increments and examined to document the development of damage. When possible, a micromechanical stress analysis was performed to aid in...
Topics: NASA Technical Reports Server (NTRS), FAILURE ANALYSIS, FIBER COMPOSITES, LAMINATES, REINFORCING...
The behavior of part-through flaws with regard to failure under monotonic loading and their growth under fatigue loading was studied experimentally and analytically. Comparisons are made of experimental values of toughness obtained using surface and corner cracked specimens with those obtained using standard test specimens, and also experimental growth cycles were compared with numerical predictions using the NASA/FLAGRO computer program. Tests were conducted on various types of surface and...
Topics: NASA Technical Reports Server (NTRS), CRACK PROPAGATION, FATIGUE (MATERIALS), FRACTURE STRENGTH,...
