Science.gov

Sample records for 24s-t aluminum-alloy flat

  1. Compressive Strength of 24S-T Aluminum-alloy Flat Panels with Longitudinal Formed Hat-section Stiffeners

    NASA Technical Reports Server (NTRS)

    Schuette, Evan H; Barab, Sual; Mccracken, Howard L

    1946-01-01

    Results are presented for a part of a test program on 24S-T aluminum alloy flat compression panels with longitudinal formed hat-section stiffeners. This part of the program is concerned with panels in which the thickness of the stiffener materials is 0.625 times the skin thickness. The results, presented in tabular and graphical form, show the effect of the relative dimensions of the panel on the buckling stress and the average stress at maximum load. Comparative envelope curves are presented for hat-stiffened and Z-stiffened panels having the same ratio of stiffener thickness to sheet thickness. These curves provide some indication of the relative structural efficiencies of the two types of panel.

  2. Charts for the minimum-weight design of 24s-t aluminum-alloy flat compression panels with longitudinal z-section stiffeners

    NASA Technical Reports Server (NTRS)

    Schuette, Evan H

    1945-01-01

    Design charts are developed for 24s-t aluminum-alloy flat compression panels with longitudinal z-section stiffeners. These charts make possible the design of the lightest panels of this type for a wide range of design requirements. Examples of the use of the charts are given and it is pointed out on the basis of these examples that, over a wide range of design conditions, the maintenance of buckle-free surfaces does not conflict with the achievement of high structural efficiency. The achievement of the maximum possible structural efficiency with 24s-t aluminum-alloy panels, however, requires closer stiffener spacings than those now in common use.

  3. Effect of Brake Forming on the Strength of 24S-T Aluminum-alloy Sheet

    NASA Technical Reports Server (NTRS)

    Heimerl, George J; Woods, Walter

    1946-01-01

    Tests were made to determine the effect of brake forming on the strength of 24S-T aluminum alloy sheet that had been formed to an inside bend radius of three times the sheet thickness. The results for both directions of the grain of the material showed that the compressive yield stresses were appreciably increased, that the tensile yield stresses were moderately increased, that the ultimate tensile stresses were only slightly increased, that the elongations were considerably reduced, and that the shapes of the tensile and compressive stress-strain curves were markedly changed.

  4. Column and Plate Compressive Strengths of Aircraft Structural Materials: Extruded 24S-T Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Heimerl, George J.; Roy, J Albert

    1945-01-01

    Column and plate compressive strengths of extruded 24S-T aluminum alloy were determined both within and beyond the elastic range from tests of thin-strip columns and local-instability tests of H-, Z-,and channel-section columns. These tests are part of an extensive research investigation to provide data on the' structural strength of various aircraft materials. The results are presented in the form of curves and charts that are suitable for use in the design and analysis of aircraft structures.

  5. Effects of Cyclic Loading on Mechanical Behavior of 24S-T4 and 75S-T6 Aluminum Alloys and SAE 4130 Steel

    NASA Technical Reports Server (NTRS)

    Macgregor, C W; Grossman, N

    1952-01-01

    An investigation was conducted to determine the effects of cyclic loading on the mechanical behavior of 24S-T4 and 75S-T6 aluminum alloys and SAE 4130 steel. Specimens of the three materials were subjected to various numbers of prior fatigue cycles both below and above the fatigue limits. Special slow-bend tests were employed to show the effects of prior cycles of fatigue stressing on the transition temperature to brittle fracture for SAE 4130 steel and on the energy-absorption capacity of the aluminum alloys. Micrographic studies were made to observe and measure crack formation and propagation and additional special tests were conducted to supplement the results of the slow-bend tests. These included Charpy impact tests, mirohardness surveys, tension tests, and fretting-corrosion studies.

  6. Axial-Load Fatigue Properties of 24S-T and 75S-T Aluminum Alloy as Determined in Several Laboratories

    NASA Technical Reports Server (NTRS)

    Grover, H J; Hyler, W S; Kuhn, Paul; Landers, Charles B; Howell, F M

    1954-01-01

    In the initial phase of a NACA program on fatigue research, axial-load tests on 24S-T3 and 75S-T6 aluminum-alloy sheet have been made at the Battelle Memorial Institute and at the Langley Aeronautical Laboratory of the National Advisory Committee for Aeronautics. The test specimens were polished and unnotched. The manufacturer of the material, the Aluminum Company of America, has made axial-load tests on 24S-T4 and 75S-T6 rod material. The test techniques used at the three laboratories are described in detail; the test results are presented and are compared with each other and with results obtained on unpolished sheet by the National Bureau of Standards. (author)

  7. Axial Fatigue Tests at Zero Mean Stress of 24S-T Aluminum-alloy Sheet with and Without a Circular Hole

    NASA Technical Reports Server (NTRS)

    Brueggeman, W C; Mayer, M JR; Smith, W H

    1944-01-01

    Axial fatigue tests were made on 189 coupon specimens of 0.032-inch 24S-T aluminum-alloy sheet and a few supplementary specimens of 0.004-inch sheet. The mean load was zero. The specimens were restrained against lateral buckling by lubricated solid guides described in a previous report on this project. About two-thirds of the 0.032-inch specimens were plain coupons nominally free from stress raisers. The remainder contained a 0.1285-inch drilled hole at the center where the reduced section was 0.5 inch wide. S-N diagrams were obtained for cycles to failure between about 1000 and 10 to the 7th power cycles for the plain specimens and 17 and 10 to the 7th power cycles for the drilled specimens. The fatigue stress concentration factor increased from about 1.08 for a stress amplitude causing failure at 0.25 cycles (static) to a maximum of 1.83 at 15,000 cycles and then decreased gradually. The graph for the drilled specimens showed less scatter than that for the plain specimens.

  8. Preliminary investigation of the compressive strength and creep lifetime of 2024-T3 (formerly 24S-T3) aluminum-alloy plates at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Mathauser, Eldon E; Deveikis, William D

    1955-01-01

    The results of elevated-temperature compressive strength and creep tests of 2024-T3 (formerly 23S-T3) aluminum-alloy plates supported in V-grooves are presented. For determining elevated-temperature strength, where creep effects are negligible, a relation previously developed for predicting plate compressive strength at room temperature was satisfactory. Creep-lifetime results are presented for the plates in the form of master creep-lifetime curves by using a time-temperature parameter that is convenient for summarizing tensile creep-rupture data. A comparison is made between tensile and compressive creep lifetime for the plates, and the magnitude by which the design stress is decreased because of material creep and loss of strength due to exposure at elevated temperatures is indicated.

  9. Axial Fatigue Tests at Zero Mean Stress of 24S-T and 75S-T Aluminum-alloy Strips with a Central Circular Hole

    NASA Technical Reports Server (NTRS)

    Brueggeman, W C; Mayer, M JR

    1948-01-01

    Axial fatigue tests at zero mean stress have been made on 0.032- and 0.064-inch 24S-T and 0.032-inch 75S-T sheet-metal specimens 1/4, 1/2, 1, and 2 inches wide without a hole and with central holes giving a range of hole diameter D to specimen width W from 0.01 to 0.95. No systematic difference was noted between the results for the 0.032-inch and the 0.064-inch specimens although the latter seemed the more consistent. In general the fatigue strength based on the minimum section dropped sharply as the ration D/W was increased from zero to about 0.25. The plain specimens showed quite a pronounced decrease in fatigue strength with increasing width. The holed specimens showed only slight and rather inconclusive evidence of this size effect. The fatigue stress-concentration factor was higher for 75S-T than for 24S-T alloy. Evidence was found that a very small hole would not cause any reduction in fatigue strength.

  10. Direct-reading design charts for 75S-T6 aluminum-alloy flat compression panels having longitudinal extruded Z-section stiffeners

    NASA Technical Reports Server (NTRS)

    Hickman, William A; Dow, Norris F

    1951-01-01

    Direct-reading design charts are presented for 75S-T6 aluminum-alloy flat compression panels having longitudinal extruded Z-section stiffeners. These charts, which cover a wide range of proportions, make possible the direct determination of the stress and all panel dimensions required to carry a given intensity of loading with a given skin thickness and effective length of panel.

  11. Aluminum alloy

    NASA Technical Reports Server (NTRS)

    Blackburn, Linda B. (Inventor); Starke, Edgar A., Jr. (Inventor)

    1989-01-01

    This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

  12. Aqueous recovery of actinides from aluminum alloys

    SciTech Connect

    Gray, J.H.; Chostner, D.F.; Gray, L.W.

    1989-01-01

    Early in the 1980's, a joint Rocky Flats/Savannah River program was established to recover actinides from scraps and residues generated during Rocky Flats purification operations. The initial program involved pyrochemical treatment of Molten Salt Extraction (MSE) chloride salts and Electrorefining (ER) anode heel metal to form aluminum alloys suitable for aqueous processing at Savannah River. Recently Rocky Flats has expressed interest in expanding the aluminum alloy program to include treatment of chloride salt residues from a modified Molten Salt Extraction process and from the Electrorefining purification operations. Samples of the current aluminum alloy buttons were prepared at Rocky Flats and sent to Savannah River Laboratory for flowsheet development and characterization of the alloys. A summary of the scrub alloy-anode heel alloy program will be presented along with recent results from aqueous dissolution studies of the new aluminum alloys. 2 figs., 4 tabs.

  13. Bearing Strengths of Some Wrought-aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Moore, R L; Wescoat, C

    1943-01-01

    Although a number of investigations of the bearing strength of aluminum alloys have been made, the problem remains one of considerable interest to the aircraft industry. For this reason it has seemed advisable to make additional tests of the commonly used aircraft alloys in an effort to establish a better basis for the selection of allowable bearing values. Current design practice does not recognize the effect of edge distance upon bearing strengths, and for this reason edge distance was one of the principal variables considered in this investigation. The increasing emphasis being placed upon permanent set limitations makes it essential that more information on bearing yield phenomena be obtained. The object of this investigation was to determine bearing yield and ultimate strengths of the following aluminum alloy products: 17S-T, 24S-T, Alclad 24S-T, 24S-RT, 52S-0, 52S-1/2H, 52S-H, 53S-T, and 61S-T extrusions. Ratios of these bearing properties to tensile properties were also determined.

  14. Microbial corrosion of aluminum alloy.

    PubMed

    Yang, S S; Chen, C Y; Wei, C B; Lin, Y T

    1996-11-01

    Several microbes were isolated from the contaminated fuel-oil in Taiwan and the microbial corrosion of aluminum alloy A356-T6 was tested by MIL-STD-810E test method. Penicillium sp. AM-F5 and Cladosporium resinac ATCC 22712 had significant adsorption and pitting on the surface of aluminum alloy, Pseudomonas acruginosa AM-B5 had weak adsorption and some precipitation in the bottom, and Candida sp. AM-Y1 had the less adsorption and few cavities formation on the surface. pH of the aqueous phase decreased 0.3 to 0.7 unit for 4 months of incubation. The corrosion of aluminum alloy was very significant in the cultures of Penicillium sp. AM-F2, Penicillium sp. AM-F5 and C. resinac ATCC 22712. The major metabolites in the aqueous phase with the inoculation of C. resinac were citric acid and oxalic acid, while succinic acid and fumaric acid were the minors. PMID:10592801

  15. Laser welding of aluminum alloys

    SciTech Connect

    Leong, K.H.; Sabo, K.R.; Sanders, P.G.; Spawr, W.J.

    1997-03-01

    Recent interest in reducing the weight of automobiles to increase fuel mileage has focused attention on the use of aluminum and associated joining technologies. Laser beam welding is one of the more promising methods for high speed welding of aluminum. Consequently, substantial effort has been expended in attempting to develop a robust laser beam welding process. Early results have not been very consistent in the process requirements but more definitive data has been produced recently. This paper reviews the process parameters needed to obtain consistent laser welds on 5,000 series aluminum alloys and discusses the research necessary to make laser processing of aluminum a reality for automotive applications.

  16. Study of stress corrosion in aluminum alloys

    NASA Technical Reports Server (NTRS)

    Brummer, S. B.

    1967-01-01

    Mechanism of the stress corrosion cracking of high-strength aluminum alloys was investigated using electrochemical, mechanical, and electron microscopic techniques. The feasibility of detecting stress corrosion damage in fabricated aluminum alloy parts by nondestructive testing was investigated using ultrasonic surface waves and eddy currents.

  17. Materials data handbook, aluminum alloy 7075

    NASA Technical Reports Server (NTRS)

    Sessler, J.; Weiss, V.

    1967-01-01

    Materials data handbook on aluminum alloy 7075 includes data on the properties of the alloy at cryogenic, ambient, and elevated temperatures, and other pertinent engineering information required for the design and fabrication of components and equipment utilizing this alloy.

  18. Advanced powder metallurgy aluminum alloys and composites

    NASA Technical Reports Server (NTRS)

    Lisagor, W. B.; Stein, B. A.

    1982-01-01

    The differences between powder and ingot metallurgy processing of aluminum alloys are outlined. The potential payoff in the use of advanced powder metallurgy (PM) aluminum alloys in future transport aircraft is indicated. The national program to bring this technology to commercial fruition and the NASA Langley Research Center role in this program are briefly outlined. Some initial results of research in 2000-series PM alloys and composites that highlight the property improvements possible are given.

  19. Seacoast stress corrosion cracking of aluminum alloys

    NASA Technical Reports Server (NTRS)

    Humphries, T. S.; Nelson, E. E.

    1981-01-01

    The stress corrosion cracking resistance of high strength, wrought aluminum alloys in a seacoast atmosphere was investigated and the results were compared with those obtained in laboratory tests. Round tensile specimens taken from the short transverse grain direction of aluminum plate and stressed up to 100 percent of their yield strengths were exposed to the seacoast and to alternate immersion in salt water and synthetic seawater. Maximum exposure periods of one year at the seacoast, 0.3 or 0.7 of a month for alternate immersion in salt water, and three months for synthetic seawater were indicated for aluminum alloys to avoid false indications of stress corrosion cracking failure resulting from pitting. Correlation of the results was very good among the three test media using the selected exposure periods. It is concluded that either of the laboratory test media is suitable for evaluating the stress corrosion cracking performance of aluminum alloys in seacoast atmosphere.

  20. Fatigue crack propagation in aerospace aluminum alloys

    NASA Technical Reports Server (NTRS)

    Gangloff, R. P.; Piascik, R. S.; Dicus, D. L.; Newman, J. C., Jr.

    1990-01-01

    This paper reviews fracture mechanics based, damage tolerant characterizations and predictions of fatigue crack growth in aerospace aluminum alloys. The results of laboratory experimentation and modeling are summarized in the areas of: (1) fatigue crack closure, (2) the wide range crack growth rate response of conventional aluminum alloys, (3) the fatigue behavior of advanced monolithic aluminum alloys and metal matrix composites, (4) the short crack problem, (5) environmental fatigue, and (6) variable amplitude loading. Remaining uncertainties and necessary research are identified. This work provides a foundation for the development of fatigue resistant alloys and composites, next generation life prediction codes for new structural designs and extreme environments, and to counter the problem of aging components.

  1. Roll Casting of Aluminum Alloy Clad Strip

    SciTech Connect

    Nakamura, R.; Tsuge, H.; Haga, T.; Watari, H.; Kumai, S.

    2011-01-17

    Casting of aluminum alloy three layers of clad strip was tried using the two sets of twin roll casters, and effects of the casting parameters on the cladding conditions were investigated. One twin roll caster was mounted on the other twin roll caster. Base strip was 8079 aluminum alloy and overlay strips were 6022 aluminum alloy. Effects of roll-load of upper and lower casters and melt temperature of the lower caster were investigated. When the roll-load of the upper and lower caster was large enough, the overlay strip could be solidified and be connected. The overlay strip could be connected when the melt of the overlay strip cast by the lower caster was low enough. Sound three layers of clad strip could be cast by proper conditions.

  2. Stress Corrosion Cracking of Certain Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Hasse, K. R.; Dorward, R. C.

    1983-01-01

    SC resistance of new high-strength alloys tested. Research report describes progress in continuing investigation of stress corrosion (SC) cracking of some aluminum alloys. Objective of program is comparing SC behavior of newer high-strength alloys with established SC-resistant alloy.

  3. PREPARATION OF URANIUM-ALUMINUM ALLOYS

    DOEpatents

    Moore, R.H.

    1962-09-01

    A process is given for preparing uranium--aluminum alloys from a solution of uranium halide in an about equimolar molten alkali metal halide-- aluminum halide mixture and excess aluminum. The uranium halide is reduced and the uranium is alloyed with the excess aluminum. The alloy and salt are separated from each other. (AEC)

  4. Weldable aluminum alloy has improved mechanical properties

    NASA Technical Reports Server (NTRS)

    Westerlund, R. W.

    1966-01-01

    Weldable aluminum alloy has good resistance to stress-corrosion cracking, shows unchanged strength and formability after storage at room temperature, and can be pre-aged, stretched, and aged. Since toxic fumes of cadmium oxide are evolved when the new alloy is welded, adequate ventilation must be provided.

  5. Materials data handbooks on aluminum alloys

    NASA Technical Reports Server (NTRS)

    Muraca, R. F.; Whittick, J. S.

    1973-01-01

    Five handbooks have been prepared which describe up-to-date properties of the following wrought-aluminum alloys: 2014, 2219, 5456, 6061, and 7075. Each handbook is divided into twelve chapters. Scope of information presented includes physical- and mechanical-property data at cryogenic, ambient, and elevated temperatures.

  6. Materials data handbook, aluminum alloy 6061

    NASA Technical Reports Server (NTRS)

    Sessler, J.; Weiss, V.

    1969-01-01

    Comprehensive compilation of technical data on aluminum alloy 6061 is presented in handbook form. The text includes data on the properties of the alloy at cryogenic, ambient, and elevated temperatures and other pertinent information required for the design and fabrication of components and equipment utilizing this alloy.

  7. Hole Expansion of Aluminum Alloys for the Automotive Industry

    NASA Astrophysics Data System (ADS)

    Stanton, M.; Bhattacharya, R.; Dargue, I.; Aylmore, R.; Williams, G.

    2011-05-01

    The introduction of Aluminum alloys in the automotive industry due to their high strength-to-weight ratio has brought with it a number of technical hurdles which require overcoming in order that their full potential may be realized. One of the issues that require addressing is that of edge cracking, a phenomenon which is particularly difficult to predict. This is often observed during the initial drawing operation in a traditional automotive stamping plant. A useful measure of a materials susceptibility to edge cracking is the Hole Expansion Ratio. Currently there is a standard (ISO 16630) which provides for holes to be expanded by a conical punch, where the original hole is introduced via punching. This reflects the traditional processing route within the automotive industry. Investigations have been conducted using both conical and flat-topped punches, as well as using drilling and reaming, and CNC machining to introduce the initial hole for comparison with the standard punched route in order to understand the effect of different processes on the susceptibility to edge cracking. The hole expansion ratio for a number of aluminum alloys, both 5xxx and 6xxx series, has been determined. Regression analyses of hole expansion ratios against material thickness and UTS have been conducted, and a relationship has been established for the different punch and hole types. Consideration is also given to combining a materials hole expansion ratio with its Forming Limit Curve (FLC), with a focus on tool design and tool buy-off being presented.

  8. Phase transformations in ternary monotectic aluminum alloys

    NASA Astrophysics Data System (ADS)

    Gröbner, Joachim; Schmid-Fetzer, Rainer

    2005-09-01

    Monotectic aluminum alloys are of interest for the development of new alloys for technological applications such as self-lubricating bearings. In contrast to the well-known binary phase diagrams, many of the ternary systems are not well established. Moreover, in a ternary monotectic alloy one may encounter the four-phase equilibrium L‧+L″+solid1+solid2, whereas in a binary system only a three-phase equilibrium L‧+L″+solid1 is possible. This opens a window for generating entirely new monotectic microstructures. The basis for such developments is the knowledge of the ternary phase diagrams and the conditions under which such four-phase reactions or different extensions of the binary monotectic reactions may form. This work presents a systematic classification of monotectic ternary aluminum alloys, illustrated by real systems. The study employs thermodynamic calculations of the ternary phase diagrams.

  9. Etching Behavior of Aluminum Alloy Extrusions

    NASA Astrophysics Data System (ADS)

    Zhu, Hanliang

    2014-11-01

    The etching treatment is an important process step in influencing the surface quality of anodized aluminum alloy extrusions. The aim of etching is to produce a homogeneously matte surface. However, in the etching process, further surface imperfections can be generated on the extrusion surface due to uneven materials loss from different microstructural components. These surface imperfections formed prior to anodizing can significantly influence the surface quality of the final anodized extrusion products. In this article, various factors that influence the materials loss during alkaline etching of aluminum alloy extrusions are investigated. The influencing variables considered include etching process parameters, Fe-rich particles, Mg-Si precipitates, and extrusion profiles. This study provides a basis for improving the surface quality in industrial extrusion products by optimizing various process parameters.

  10. Diffusion bonding of superplastic aluminum alloys

    SciTech Connect

    Sunwoo, A.J.

    1993-12-01

    Ability to diffusion bond aluminum alloys, in particular superplastic aluminum alloys, will complete the technology-base that is strongly needed to enhance the use of superplastic forming (SPF) technology. Concurrent diffusion bonding (DB)-SPF is considered to be an energy-saving manufacturing process since it simplifies the production of complex components. Moreover, because of increased design flexibility, overall manufacturing cost and component weight are significantly reduced. Diffusion bonding is an attractive manufacturing option for applications where the preservation of the base metal microstructure and, in turn, mechanical properties is imperative in the bond area. The process utilizes either the solid state or transient liquid phase (TLP) bonding to produce a bond with microstructure continuity in the joint. In addition, there is no localized thermal gradient present to induce distortion or to create residual stresses in the component, thereby increasing structural integrity.

  11. FABRICATION OF URANIUM-ALUMINUM ALLOYS

    DOEpatents

    Saller, H.A.

    1959-12-15

    A process is presented for producing a workable article of a uranium- aluminum alloy in which the uranium content is between 14 and 70% by weight; aluminum powder and powdered UAl/sub 2/, UAl/sub 3/, UAl/sub 5/, or UBe/sub 9/ are mixed, and the mixture is compressed into the shape desired and sintered at between 450 and 600 deg C.

  12. Degassing of Aluminum Alloys Using Ultrasonic Vibration

    SciTech Connect

    Meek, T. T.; Han, Q.; Xu, H.

    2006-06-01

    The research was intended to lead to a better fundamental understanding of the effect of ultrasonic energy on the degassing of liquid metals and to develop practical approaches for the ultrasonic degassing of alloys. The goals of the project described here were to evaluate core principles, establish a quantitative basis for the ultrasonic degassing of aluminum alloy melts, and demonstrate the application of ultrsaonic processing during ingot casting and foundry shape casting.

  13. Torsional Stability of Aluminum Alloy Seamless Tubing

    NASA Technical Reports Server (NTRS)

    Moore, R L; Paul, D A

    1939-01-01

    Torsion tests were made on 51ST aluminum-alloy seamless tubes having diameter-to-thickness ratios of from 77 to 139 and length-to-diameter ratios of from 1 to 60. The torsional strengths developed in the tubes which failed elastically (all tubes having lengths greater than 2 to 6 times the diameter) were in most cases within 10 percent of the value indicated by the theories of Donnel, Timoshenko, and Sturm, assuming a condition of simply supported ends.

  14. Aluminum Alloy and Article Cast Therefrom

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2003-01-01

    A cast article from an aluminum alloy, which has improved mechanical properties at elevated temperatures, has the following composition in weight percent: Silicon 14 - 25.0, Copper 5.5 - 8.0, Iron 0.05 - 1.2, Magnesium 0.5 - 1.5, Nickel 0.05 - 0.9, Manganese 0.05 - 1.0, Titanium 0.05 - 1.2, Zirconium 0.05 - 1.2, Vanadium 0.05 - 1.2, Zinc 0.05 - 0.9, Phosphorus 0.001 - 0.1, and the balance is Aluminum, wherein the silicon-to-magnesium ratio is 10 - 25, and the copper-to-magnesium ratio is 4 - 15. The aluminum alloy contains a simultaneous dispersion of three types of Al3X compound particles (X=Ti, V, Zr) having a LI2, crystal structure, and their lattice parameters are coherent to the aluminum matrix lattice. A process for producing this cast article is also disclosed, as well as a metal matrix composite, which includes the aluminum alloy serving as a matrix and containing up to about 60% by volume of a secondary filler material.

  15. Corrosion potential for aluminum alloys measured by ASTM G 69

    SciTech Connect

    Burleigh, T.D. ); Bovard, F.S. ); Rennick, R.C.

    1993-08-01

    ASTM G 69, [open quotes]Standard Practice for Measurement of Corrosion Potentials of Aluminum Alloys[close quotes], is a useful method to discern the temper of a given aluminum alloy. Corrosion potentials (E[sub corr]) often can be used to differentiate between different alloys since copper or zinc in solid solution will cause significant differences in E[sub corr]. Measured E[sub corr] of various aluminum alloys and other non-aluminum metals were listed.

  16. Three year performance of aluminum alloy galvanic cathodic protection system

    SciTech Connect

    Funahashi, M.; Young, W.T.

    1999-07-01

    A newly developed aluminum alloy galvanic cathodic protection system was installed on selected prestressed concrete piles. The piles were instrumented to measure the aluminum alloy anode performance. To evaluate the new anode, the pure zinc anode was used for the comparison purpose. The anode performance was monitored for the three years since the system was installed in June, 1996. This paper discusses the results of the performance of the new aluminum alloy anode.

  17. Fatigue Strength and Related Characteristics of Aircraft Joints I : Comparison of Spot-Weld and Rivet Patterns in 24s-t Alclad and 75s-t Alclad

    NASA Technical Reports Server (NTRS)

    Russell, H W; Jackson, L R; Grover, H J; Beaver, W W

    1944-01-01

    Report contains detailed results of a number of fatigue tests on spot-welded joints in aluminum alloys. The tests described include: (1) fatigue tests on spot-welded lap joints in sheets of unequal thickness of alclad 24s-t. These tests indicate that the fatigue strength of a spot-welded joint in sheets of two different gages is slightly higher than that of a similar joint in two sheets of the thinner gage but definitely lower than that of a similar joint in two sheets of the thicker gage. (2) Fatigue tests on spot-welded alclad 75s-t spot-welded lap-joint specimens of alclad 75s-t were not any stronger in fatigue than similar specimens of alclad 24s-t. (3) Fatigue tests on lap-joint specimens spot -welded after various surface preparations--these included ac welding wire-brushed surfaces, dc welding wire-brushed surfaces, and dc welding chemically cleaned surfaces. While the ac welds were strongest statically, the dc welds on wire-brushed surfaces were strongest in fatigue. Specimens prepared in this way were very nearly as strong as the best riveted specimens tested for comparison. (4) Fatigue tests on specimens spot-welded with varying voltage so as to include a wide range of static spot-weld strengths. The fatigue strengths were in the same order as the static strengths but showed less range. (author)

  18. Fatigue Strength and Related Characteristics of Joints in 24s-t Alclad Sheet

    NASA Technical Reports Server (NTRS)

    Russell, H W; Jackson, L R; Grover, H J; Beaver, W W

    1944-01-01

    Report includes tension fatigue test results on the following types of samples of 0.040-inch alclad 24s-t: (1) monoblock sheet samples as received and after a post-aging heat treatment, (2) "sheet efficiency" samples (two equally stressed sheets joined by a single transverse row of spot welds) both as received and after post-aging, (3) spot-welded lap-joint samples as received and after post-aging, and (4) roll-welded lap-joint samples. (author)

  19. Corrosion of aluminum alloys by chlorinated hydrocarbon/methanol mixtures

    NASA Technical Reports Server (NTRS)

    De Forest, W. S.

    1967-01-01

    Laboratory investigations show that water-free mixtures of Freon MF /trichlorofluoromethane/ and methanol vigorously attack aluminum alloys which contain significant amounts of copper. Freon MF alone did not attack the aluminum alloys at room temperature. Pure methanol had only a slight corrosive effect on the alloy.

  20. Dimensional control of quasisingle crystals of aluminum alloy in production

    SciTech Connect

    Radchenko, A.I.; Karuskevich, M.V.; Naim, V.R.

    1995-01-01

    The article deals with a method of controlling the dimensions of quasisingle crystal grains of an aluminum alloy used instead of single crystal specimens in static fatigue tests with the object of substantiating a discrete probabilistic model of the fatigue of metals and alloys. We obtained a mathematical model of dimensional control of quasisingle crystals of the aluminum alloy.

  1. Mechanical properties of iron-aluminum alloys

    SciTech Connect

    Alexander, D.J.; Sikka, V.K.

    1993-07-01

    Tensile and impact tests have been conducted on specimens for a series of five heats of iron-aluminum alloys. These results have been compared to data for the iron aluminide alloy FA-129. The first of the new alloys was a simple ternary alloy with iron, aluminum, and chromium contents that matched the FA-129 composition. The second was similar but with additions of zirconium and carbon. Three heats were produced with reduced aluminum contents so that a disordered body-centered cubic structure would be present. Additions of titanium or yttrium were included. The ductile-to brittle transition temperatures of all of the Fe{sub 3}Al alloys were similar, but the simple ternary alloy had a much higher upper-shelf energy levels than the Fe{sub 3}Al type alloys. The reduced aluminum alloy with the yttrium addition showed excellent tensile properties, with a room temperature total elongation of over 40%, and a very high upper-shelf energy level. Despite the high tensile ductility at room temperature, the transition temperature of the yttrium-containing alloy was still about 150{degrees}C, compared to approximately 300{degrees}C for FA-129.

  2. Molten aluminum alloy fuel fragmentation experiments

    SciTech Connect

    Gabor, J.D.; Purviance, R.T.; Cassulo, J.C.; Spencer, B.W.

    1992-09-01

    Experiments were conducted in which molten aluminum alloys were injected into a 1.2 m deep pool of water. The parameters varied were (i) injectant material (8001 aluminum alloy and 12.3 wt% U-87.7 wt% Al), (ii) melt superheat (O to 50 K), (iii) water temperature (313, 343 and 373 K) and (iv) size and geometry of the pour stream (5, 10 and 20 mm diameter circular and 57 mm annular). The pour stream fragmentation was dominated by surface tension with large particles ({approximately}30 mm) being formed from varicose wave breakup of the 10-mm circular pours and from the annular flow off a 57 mm diameter tube. The fragments produced by the 5 mm circular et were smaller ({approximately} mm), and the 20 mm jet which underwent sinuous wave breakup produced {approximately}100 mm fragments. The fragments froze to form solid particles in 313 K water, and when the water was {ge}343 K, the melt fragments did not freeze during their transit through 1.2 m of water.

  3. Molten aluminum alloy fuel fragmentation experiments

    SciTech Connect

    Gabor, J.D.; Purviance, R.T.; Cassulo, J.C.; Spencer, B.W.

    1992-01-01

    Experiments were conducted in which molten aluminum alloys were injected into a 1.2 m deep pool of water. The parameters varied were (i) injectant material (8001 aluminum alloy and 12.3 wt% U-87.7 wt% Al), (ii) melt superheat (O to 50 K), (iii) water temperature (313, 343 and 373 K) and (iv) size and geometry of the pour stream (5, 10 and 20 mm diameter circular and 57 mm annular). The pour stream fragmentation was dominated by surface tension with large particles ({approximately}30 mm) being formed from varicose wave breakup of the 10-mm circular pours and from the annular flow off a 57 mm diameter tube. The fragments produced by the 5 mm circular et were smaller ({approximately} mm), and the 20 mm jet which underwent sinuous wave breakup produced {approximately}100 mm fragments. The fragments froze to form solid particles in 313 K water, and when the water was {ge}343 K, the melt fragments did not freeze during their transit through 1.2 m of water.

  4. Investigation of the Compressive Strength and Creep Lifetime of 2024-T3 Aluminum-Alloy Plates at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Mathauser, Eldon E; Deveikis, William D

    1957-01-01

    The results of elevated-temperature compressive strength and creep tests of 2024-t3 (formerly 24s-t3) aluminum alloy plates supported in v-grooves are presented. The strength-test results indicate that a relation previously developed for predicting plate compressive strength for plates of all materials at room temperature is also satisfactory for determining elevated-temperature strength. Creep-lifetime results are presented for plates in the form of master creep-lifetime curves by using a time-temperature parameter that is convenient for summarizing tensile creep-rupture data. A comparison is made between tensile and compressive creep lifetime for the plates and a method that made use of isochronous stress-strain curves for predicting plate-creep failure stresses is investigated.

  5. Laser perforation of aluminum alloy sheet

    NASA Astrophysics Data System (ADS)

    Migliore, Leonard; Nazary, George

    2010-02-01

    Recent advances in the design of gain modules for diode-pumped solid-state lasers have allowed the manufacture of high-powered Q-switched products. The high available pulse energy and good mode quality enable highly efficient harmonic conversion, enabling the generation of several hundred watts of average power at a wavelength of 532nm. Among the applications for which this class of product may be suited is the rapid drilling of small-diameter holes in aluminum sheet. To investigate this application, plates of several aluminum alloys were drilled under a variety of conditions. The drilled plates were sectioned and subjected to analysis by optical metallography. The initial results indicate ways in which the process may be optimized.

  6. Abnormal Grain Growth Suppression in Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Hales, Stephen J. (Inventor); Claytor, Harold Dale (Inventor); Alexa, Joel A. (Inventor)

    2015-01-01

    The present invention provides a process for suppressing abnormal grain growth in friction stir welded aluminum alloys by inserting an intermediate annealing treatment ("IAT") after the welding step on the article. The IAT may be followed by a solution heat treatment (SHT) on the article under effectively high solution heat treatment conditions. In at least some embodiments, a deformation step is conducted on the article under effective spin-forming deformation conditions or under effective superplastic deformation conditions. The invention further provides a welded article having suppressed abnormal grain growth, prepared by the process above. Preferably the article is characterized with greater than about 90% reduction in area fraction abnormal grain growth in any friction-stir-welded nugget.

  7. Failure analysis of aluminum alloy components

    NASA Technical Reports Server (NTRS)

    Johari, O.; Corvin, I.; Staschke, J.

    1973-01-01

    Analysis of six service failures in aluminum alloy components which failed in aerospace applications is reported. Identification of fracture surface features from fatigue and overload modes was straightforward, though the specimens were not always in a clean, smear-free condition most suitable for failure analysis. The presence of corrosion products and of chemically attacked or mechanically rubbed areas here hindered precise determination of the cause of crack initiation, which was then indirectly inferred from the scanning electron fractography results. In five failures the crack propagation was by fatigue, though in each case the fatigue crack initiated from a different cause. Some of these causes could be eliminated in future components by better process control. In one failure, the cause was determined to be impact during a crash; the features of impact fracture were distinguished from overload fractures by direct comparisons of the received specimens with laboratory-generated failures.

  8. Alkaline oxide conversion coatings for aluminum alloys

    SciTech Connect

    Buchheit, R.G.

    1996-02-01

    Three related conversion coating methods are described that are based on film formation which occurs when aluminum alloys are exposed to alkaline Li salt solutions. Representative examples of the processing methods, resulting coating structure, composition and morphology are presented. The corrosion resistance of these coatings to aerated 0.5 M NaCl solution has been evaluated as a function of total processing time using electrochemical impedance spectroscopy (EIS). This evaluation shows that excellent corrosion resistance can be uniformly achieved using no more than 20 minutes of process time for 6061-T6. Using current methods a minimum of 80 minutes of process time is required to get marginally acceptable corrosion resistance for 2024-T3. Longer processing times are required to achieve uniformly good corrosion resistance.

  9. Predicting fracture behavior of aluminum alloys

    SciTech Connect

    Chang, A.T.; Cordes, J.A.

    1997-12-31

    A computational method has been developed to predict the material fracture failure process in flawed or cracked specimens. This method does not require experimental material fracture data. Finite element technique is employed to model the physical shape of the specimen. Nonlinear spring elements are introduced to model the material damage behavior near a flaw or a crack tip. Crack initiation and crack propagation conditions are developed to predict the crack initiation load, the extent of material damage, and the crack growth behavior. The introduction of nonlinear spring elements and the development of crack initiation and crack growth conditions are unique features for fracture prediction with the development of this method. To prove the feasibility of the method, two types of specimen made by two aluminum alloys with similar material stress-strain data were studied. Fracture predictions by this method are comparable to experimental data.

  10. NASA-427: A New Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Nabors, Sammy A.

    2015-01-01

    NASA's Marshall Space Flight Center researchers have developed a new, stronger aluminum alloy, ideal for cast aluminum products that have powder or paint-baked thermal coatings. With advanced mechanical properties, the NASA-427 alloy shows greater tensile strength and increased ductility, providing substantial improvement in impact toughness. In addition, this alloy improves the thermal coating process by decreasing the time required for heat treatment. With improvements in both strength and processing time, use of the alloy provides reduced materials and production costs, lower product weight, and better product performance. The superior properties of NASA-427 can benefit many industries, including automotive, where it is particularly well-suited for use in aluminum wheels.

  11. Laser assisted arc welding for aluminum alloys

    SciTech Connect

    Fuerschbach, P.W.

    2000-01-01

    Experiments have been performed using a coaxial end-effector to combine a focused laser beam and a plasma arc. The device employs a hollow tungsten electrode, a focusing lens, and conventional plasma arc torch nozzles to co-locate the focused beam and arc on the workpiece. Plasma arc nozzles were selected to protect the electrode from laser generated metal vapor. The project goal is to develop an improved fusion welding process that exhibits both absorption robustness and deep penetration for small scale (<1.5 mm thickness) applications. On aluminum alloys 6061 and 6111, the hybrid process has been shown to eliminate hot cracking in the fusion zone. Fusion zone dimensions for both stainless steel and aluminum were found to be wider than characteristic laser welds, and deeper than characteristic plasma arc welds.

  12. Machinability of hypereutectic silicon-aluminum alloys

    NASA Astrophysics Data System (ADS)

    Tanaka, T.; Akasawa, T.

    1999-08-01

    The machinability of high-silicon aluminum alloys made by a P/M process and by casting was compared. The cutting test was conducted by turning on lathes with the use of cemented carbide tools. The tool wear by machining the P/M alloy was far smaller than the tool wear by machining the cast alloy. The roughness of the machined surface of the P/M alloy is far better than that of the cast alloy, and the turning speed did not affect it greatly at higher speeds. The P/M alloy produced long chips, so the disposal can cause trouble. The size effect of silicon grains on the machinability is discussed.

  13. Gas-tungsten arc welding of aluminum alloys

    DOEpatents

    Frye, Lowell D.

    1984-01-01

    A gas-tungsten arc welding method for joining together structures formed of aluminum alloy with these structures disposed contiguously to a heat-damagable substrate of a metal dissimilar to the aluminum alloy. The method of the present invention is practiced by diamond machining the fay surfaces of the aluminum alloy structures to provide a mirror finish thereon having a surface roughness in the order of about one microinch. The fay surfaces are aligned and heated sufficiently by the tungsten electrode to fuse the aluminum alloy contiguous to the fay surfaces to effect the weld joint. The heat input used to provide an oxide-free weld is significantly less than that required if the fay surfaces were prepared by using conventional chemical and mechanical practices.

  14. Gas-tungsten arc welding of aluminum alloys

    DOEpatents

    Frye, L.D.

    1982-03-25

    The present invention is directed to a gas-tungsten arc welding method for joining together structures formed of aluminum alloy with these structures disposed contiguously to a heat-damagable substrate of a metal dissimilar to the aluminum alloy. The method of the present invention is practiced by diamond machining the fay surfaces of the aluminum alloy structures to profice a mirror finish thereon having a surface roughness in the order of about one microinch. The fay surface are aligned and heated sufficiently by the tungsten electrode to fuse the aluminum alloy continguous to the fay surfaces to effect the weld joint. The heat input used to provide an oxide-free weld is significantly less than that required if the fay surfaces were prepared by using conventional chemical and mechanical practices.

  15. Measurement of Thermodynamic Properties of Titanium Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Mehrotra, Gopal

    1995-01-01

    This final report is a summary of the work done by Professor Mehrotra at NASA Lewis Research Center. He has worked extensively on the measurement of thermodynamic properties of titanium aluminum alloys over the past six years.

  16. Selecting an Algicide for Use with Aluminum Alloys

    SciTech Connect

    Wilde, E.W.

    2001-03-15

    This paper discusses the testing and results of five relatively noncorrosive commercially available compounds compared with one another and with sodium hypochlorite for their potential applicability as algicides in water systems containing aluminum alloys.

  17. Paint-Bonding Improvement for 2219 Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Daech, Alfred F.; Cibula, Audrey Y.

    1987-01-01

    Bonding of adhesives and primers to 2219 aluminum alloy improved by delaying rinse step in surface-treatment process. Delaying rinse allows formation of rougher surface for stronger bonding and greater oxide buildup.

  18. Stress-corrosion-induced property changes in aluminum alloys

    NASA Technical Reports Server (NTRS)

    Bankston, B. F.; Clotfelter, W. N.

    1968-01-01

    Measurements of electrical conductivity, ultrasonic surface wave attenuation, and internal friction loss were made on aluminum alloys 7079-T6, 2219-T31, and 2219-T81 as a function of the onset of stress corrosion.

  19. Systems study of transport aircraft incorporating advanced aluminum alloys

    NASA Technical Reports Server (NTRS)

    Sakata, I. F.

    1982-01-01

    A study was performed to quantify the potential benefits of utilizing advanced aluminum alloys in commercial transport aircraft and to define the effort necessary to develop fully the alloys to a viable commercial production capability. The comprehensive investigation (1) established realistic advanced aluminum alloy property goals to maximize aircraft systems effectiveness (2) identified performance and economic benefits of incorporating the advanced alloy in future advanced technology commercial aircraft designs (3) provided a recommended plan for development and integration of the alloys into commercial aircraft production (4) provided an indication of the timing and investigation required by the metal producing industry to support the projected market and (5) evaluate application of advanced aluminum alloys to other aerospace and transit systems as a secondary objective. The results of the investigation provided a roadmap and identified key issues requiring attention in an advanced aluminum alloy and applications technology development program.

  20. Texture, microstructure and formability of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Cheng, Xiang-Ming

    Texture, microstructure and formability were studied in Direct Chill Cast (DC) and Strip Cast (SC) aluminum alloys with regard to crystallographic anisotropy, the Portevin-Le Chatelier effect and aging softening behavior. It was found that material properties change greatly with manufacturing processes (DC vs. SC) and chemical composition (3xxx vs. 5xxx alloys). DC cast hot band materials are usually fully recrystallized and have strong softening textures while SC hot band materials have a rolling structure with strong deformation textures. Softening textures cause 90° earing, while deformation textures result in 45° earing after deep drawing. During cold rolling, 90° earing in DC cast hot band materials decreases and eventually changes to 45° earing after certain degrees of cold reduction. Correspondingly, the intensity of the softening texture components in DC cast hot band materials decreases while the intensity of deformation texture components increases with increasing degrees of cold reduction. These two kinds of textures interact and attempt to balance each other during cold rolling which produces resultant earing. However, this is not true for SC hot band materials since it's hard to obtain strong softening textures and thus 90° earing in these materials. 5xxx Al-Mg alloys are more difficult to work than 3xxx aluminum alloys. Elevated temperature annealing, which greatly reduces the strength (hardness), improves significantly the workability of Al-Mg alloys. On the other hand, the Portevin-Le Chatelier effect and aging softening behavior are stronger in Al-Mg alloys than in 3xxx aluminum alloys, and both increase with increasing cold reduction and with increasing Mg content. An apparent tensile anisotropy exists in as received SC hot band materials. The tensile yield strength (YS) is smaller in the QD (45° to the rolling direction) and larger in the RD (rolling direction) and the TD (transverse direction). There is no obvious difference in YS between

  1. Spray-forming monolithic aluminum alloy and metal matrix composite strip

    SciTech Connect

    McHugh, K.M.

    1995-10-01

    Spray forming with de Laval nozzles is an advanced materials processing technology that converts a bulk liquid metal to a near-net-shape solid by depositing atomized droplets onto a suitably shaped substrate. Using this approach, aluminum alloys have been spray formed as strip, with technoeconomic advantages over conventional hot mill processing and continuous casting. The spray-formed strip had a flat profile, minimal porosity, high yield, and refined microstructure. In an adaptation to the technique, 6061 Al/SiC particulate-reinforced metal matrix composite strip was produced by codeposition of the phases.

  2. Friction Pull Plug Welding in Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Brooke, Shane A.; Bradford, Vann; Burkholder, Jonathon

    2011-01-01

    NASA fs Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for External Tank. FPPW was easily selected as the primary process used to close out the termination hole on the Constellation Program fs ARES I Upper Stage circumferential Self ] Reacting Friction Stir Welds (SR ]FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR ]FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process fs limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

  3. Friction Pull Plug Welding in Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Brooke, Shane A.; Bradford, Vann

    2012-01-01

    NASA's Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for the Space Shuttle fs External Tank. FPPW was easily selected as the primary weld process used to close out the termination hole on the Constellation Program's ARES I Upper Stage circumferential Self-Reacting Friction Stir Welds (SR-FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR-FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process's limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

  4. Aluminum alloy clad fiber optic corrosion sensor

    NASA Astrophysics Data System (ADS)

    Rutherford, Paul S.; Ikegami, Roy; Shrader, John E.; Sherrer, David; Zabaronick, Noel; Zeakes, Jason S.; Murphy, Kent A.; Claus, Richard O.

    1997-06-01

    Life extension programs for military metallic aircraft are becoming increasingly important as defense budgets shrink and world economies realign themselves to an uncertain future. For existing military weapon systems, metallic corrosion damage costs as estimated $DOL8 billion per year. One approach to reducing this cost is to develop a reliable method to detect and monitor corrosion in hidden metallic structure with the use of corrosion sensors which would give an early indication of corrosion without significant disassembly, thereby reducing maintenance costs. This presentation describes the development, analysis, and testing of a fiber optic corrosion sensor developed jointly with the Virginia Polytechnic Fiber and Electro-Optics Research Center and sponsored by Wright Laboratory Materials Directorate. In the sensor which was researched, the normal cladding is removed in the sensor region, and replaced with aluminum alloy and allowed to corrode on coupons representative of C/KC-135 body structure in an ASTM B117 salt spray chamber and a Boeing developed Crevice Corrosion Cell. In this approach, the optical signal output of the sensor was originally designed to increase as corrosion takes place, however interaction with the corrosion byproducts yielded different results than anticipated. These test results to determine a correlation between the sensor output and the structural degradation due to corrosion are discussed.

  5. Aluminum-Alloy-Matrix/Alumina-Reinforcement Composites

    NASA Technical Reports Server (NTRS)

    Kashalikar, Uday; Rozenoyer, Boris

    2004-01-01

    Isotropic composites of aluminum-alloy matrices reinforced with particulate alumina have been developed as lightweight, high-specific-strength, less-expensive alternatives to nickel-base and ferrous superalloys. These composites feature a specific gravity of about 3.45 grams per cubic centimeter and specific strengths of about 200 MPa/(grams per cubic centimeter). The room-temperature tensile strength is 100 ksi (689 MPa) and stiffness is 30 Msi (206 GPa). At 500 F (260 C), these composites have shown 80 percent retention in strength and 95 percent retention in stiffness. These materials also have excellent fatigue tolerance and tribological properties. They can be fabricated in net (or nearly net) sizes and shapes to make housings, pistons, valves, and ducts in turbomachinery, and to make structural components of such diverse systems as diesel engines, automotive brake systems, and power-generation, mining, and oil-drilling equipment. Separately, incorporation of these metal matrix composites within aluminum gravity castings for localized reinforcement has been demonstrated. A composite part of this type can be fabricated in a pressure infiltration casting process. The process begins with the placement of a mold with alumina particulate preform of net or nearly net size and shape in a crucible in a vacuum furnace. A charge of the alloy is placed in the crucible with the preform. The interior of the furnace is evacuated, then the furnace heaters are turned on to heat the alloy above its liquidus temperature. Next, the interior of the furnace is filled with argon gas at a pressure about 900 psi (approximately equal to 6.2 MPa) to force the molten alloy to infiltrate the preform. Once infiltrated, the entire contents of the crucible can be allowed to cool in place, and the composite part recovered from the mold.

  6. Friction stir welding process to repair voids in aluminum alloys

    NASA Technical Reports Server (NTRS)

    Rosen, Charles D. (Inventor); Litwinski, Edward (Inventor); Valdez, Juan M. (Inventor)

    1999-01-01

    The present invention provides an in-process method to repair voids in an aluminum alloy, particularly a friction stir weld in an aluminum alloy. For repairing a circular void or an in-process exit hole in a weld, the method includes the steps of fabricating filler material of the same composition or compatible with the parent material into a plug form to be fitted into the void, positioning the plug in the void, and friction stir welding over and through the plug. For repairing a longitudinal void (30), the method includes machining the void area to provide a trough (34) that subsumes the void, fabricating filler metal into a strip form (36) to be fitted into the trough, positioning the strip in the trough, and rewelding the void area by traversing a friction stir welding tool longitudinally through the strip. The method is also applicable for repairing welds made by a fusing welding process or voids in aluminum alloy workpieces themselves.

  7. Issues for conversion coating of aluminum alloys with hydrotalcite

    SciTech Connect

    Drewien, C.A.; Buchheit, R.G.

    1993-12-01

    Hydrotalcite coatings on aluminum alloys are being developed for corrosion protection of aluminum in aggressive saline environments. Coating bath composition, surface pretreatment, and alloying elements in aluminum all influence the performance of these coatings during salt spray testing. The coating bath, comprised of lithium carbonate, requires aging by dissolution of aluminum into the bath in order to grow corrosion resistant coatings. Coatings formed in non- aged baths do not perform well in salt spray testing. The alloying elements in aluminum alloys, especially copper, influence the coating growth and formation leading to thin coatings. The effect of the alloy elements is to limit the supply of aluminum to the coating/electrolyte interface and hinder growth of hydrotalcite upon aluminum alloys.

  8. MICROSTRUCTURE EVOLUTION MODELING FOR SOLUTION TREATMENT OF ALUMINUM ALLOYS

    SciTech Connect

    Yin, Hebi; Sabau, Adrian S; Skszek, Timothy; Niu, X

    2013-01-01

    The microstructure evolution during solution treatment plays an important role in mechanical properties of heat-treated aluminum alloys. In this paper, models were reviewed that can predict the microstructure evolution during the solutionizing process of the aging heat treatment of aluminum alloys. The dissolution of Mg2Si particles has been modeled as a diffusion process of Mg in the -Al matrix. The evolution of volumetric fraction of fragmented silicon as a function of time and temperature was also considered. The growth and coarsening of silicon particles during the heat treatment was considered. It was found that constitutive equations and required property data for most of the phenomena that need to be considered are available. Several model parameters that need to be obtained from material characterization were identified. Pending the availability of these model parameters, this comprehensive model can be used to describe the microstructure evolution of aluminum alloys in order to optimize the solutionizing heat treatment for energy savings.

  9. Elevated temperature crack growth in aluminum alloys: Tensile deformation of 2618 and FVS0812 aluminum alloys

    NASA Technical Reports Server (NTRS)

    Leng, Yang; Gangloff, Richard P.

    1990-01-01

    Understanding the damage tolerance of aluminum alloys at elevated temperatures is essential for safe applications of advanced materials. The objective of this project is to investigate the time dependent subcritical cracking behavior of powder metallurgy FVS0812 and ingot metallurgy 2618 aluminum alloys at elevated temperatures. The fracture mechanics approach was applied. Sidegrooved compact tension specimens were tested at 175, 250, and 316 C under constant load. Subcritical crack growth occurred in each alloy at applied stress intensity levels (K) of between about 14 and 25 MPa/m, well below K (sub IC). Measured load, crack opening displacement and displacement rate, and crack length and growth rate (da/dt) were analyzed with several continuum fracture parameters including, the C-integral, C (sub t), and K. Elevated temperature growth rate data suggest that K is a controlling parameter during time dependent cracking. For FVS0812, da/dt is highest at 175 C when rates are expressed as a function of K. While crack growth rate is not controlled by C (sub t) at 175 C, da/dt appears to better correlate with C (sub t) at higher temperatures. Creep brittle cracking at intermediate temperatures, and perhaps related to strain aging, is augmented by time dependent transient creep plasticity at higher temperatures. The C (sub t) analysis is, however, complicated by the necessity to measure small differences in the elastic crack growth and creep contributions to the crack opening displacement rate. A microstructural study indicates that 2618 and FVS0812 are likely to be creep brittle materials, consistent with the results obtained from the fracture mechanics study. Time dependent crack growth of 2618 at 175 C is characterized by mixed transgranular and intergranular fracture. Delamination along the ribbon powder particle boundaries occurs in FVS0812 at all temperatures. The fracture mode of FVS0812 changes with temperature. At 175 C, it is characterized as dimpled rupture

  10. Simulating weld-fusion boundary microstructures in aluminum alloys

    NASA Astrophysics Data System (ADS)

    Kostrivas, Anastasios D.; Lippold, John C.

    2004-02-01

    A fundamental study of weld-fusion boundary microstructure evolution in aluminum alloys was conducted in an effort to understand equiaxed grain zone formation and fusion boundary nucleation and growth phenomena. In addition to commercial aluminum alloys, experimental Mg-bearing alloys with Zr and Sc additions were studied along with the widely used Cu- and Licontaining alloy 2195-T8. This article describes work conducted to clarify the interrelation among composition, base metal substrate, and temperature as they relate to nucleation and growth phenomena at the fusion boundary.

  11. Environment enhanced fatigue of advanced aluminum alloys and composites

    NASA Technical Reports Server (NTRS)

    Slavik, Donald C.; Gangloff, Richard P.

    1990-01-01

    The objective is to characterize and understand the environmental fatigue crack propagation behavior of advanced, high stiffness and strength, aluminum alloys and metal matrix composites. Those gases and aqueous electrolytes which are capable of producing atomic hydrogen by reactions on clean crack surfaces are emphasized. Characterizations of the behavior of new materials are sought to provide data for damage tolerant component life prediction. Mechanistic models are sought for crack tip damage processes which are generally applicable to structural aluminum alloys. Such models will enable predictions of cracking behavior outside of the data, metallurgical improvements in material cracking resistance, and insight on hydrogen compatibility.

  12. Aluminum alloy welding and stress-corrosion testing. Final report

    SciTech Connect

    Gates, W.G.; Jimenez, E.

    1981-04-01

    The weldability, strength, and corrosion resistance of four 5XXX aluminum alloys electron beam welded to 6061-T6 aluminum alloy without a filler metal were evaluated. Adding filler metal raises weld energy requirements and makes the process more difficult to control. In this study, instead of using a filler metal, a high-magnesium 5XXX alloy was welded to the 6061 alloy. The four 5XXX alloys used (5456-H321, 5052-H34, 5086-H323, and 5083-H32) were selected for their high magnesium content which reduces weld crack sensitivity.

  13. High strength cast aluminum alloy development

    NASA Astrophysics Data System (ADS)

    Druschitz, Edward A.

    The goal of this research was to understand how chemistry and processing affect the resulting microstructure and mechanical properties of high strength cast aluminum alloys. Two alloy systems were investigated including the Al-Cu-Ag and the Al-Zn-Mg-Cu systems. Processing variables included solidification under pressure (SUP) and heat treatment. This research determined the range in properties that can be achieved in BAC 100(TM) (Al-Cu micro-alloyed with Ag, Mn, Zr, and V) and generated sufficient property data for design purposes. Tensile, stress corrosion cracking, and fatigue testing were performed. CuAl2 and Al-Cu-Fe-Mn intermetallics were identified as the ductility limiting flaws. A solution treatment of 75 hours or longer was needed to dissolve most of the intermetallic CuAl 2. The Al-Cu-Fe-Mn intermetallic was unaffected by heat treatment. These results indicate that faster cooling rates, a reduction in copper concentration and a reduction in iron concentration might increase the ductility of the alloy by decreasing the size and amount of the intermetallics that form during solidification. Six experimental Al-Zn-Mg-Cu series alloys were produced. Zinc concentrations of 8 and 12wt% and Zn/Mg ratios of 1.5 to 5.5 were tested. Copper was held constant at 0.9%. Heat treating of the alloys was optimized for maximum hardness. Al-Zn-Mg-Cu samples were solution treated at 441°C (826°F) for 4 hours before ramping to 460°C (860°F) for 75 hours and then aged at 120°C (248°F) for 75 hours. X-ray diffraction showed that the age hardening precipitates in most of these alloys was the T phase (Mg32Zn 31.9Al17.1). Tensile testing of the alloys showed that the best mechanical properties were obtained in the lowest alloy condition. Chilled Al-8.2Zn-1.4Mg-0.9Cu solidified under pressure resulted in an alloy with a yield strength of 468MPa (68ksi), tensile strength of 525MPa (76ksi) and an elongation of 9%.

  14. Fusion boundary microstructure evolution in aluminum alloys

    NASA Astrophysics Data System (ADS)

    Kostrivas, Anastasios Dimitrios

    2000-10-01

    A melting technique was developed to simulate the fusion boundary of aluminum alloys using the GleebleRTM thermal simulator. Using a steel sleeve to contain the aluminum, samples were heated to incremental temperatures above the solidus temperature of a number of alloys. In alloy 2195, a 4wt%Cu-1wt%Li alloy, an equiaxed non-dendritic zone (EQZ) could be formed by heating in the temperature range from approximately 630 to 640°C. At temperatures above 640°C, solidification occurred by the normal epitaxial nucleation and growth mechanism. Fusion boundary behavior was also studied in alloys 5454-H34, 6061-T6, and 2219-T8. Additionally, experimental alloy compositions were produced by making bead on plate welds using an alloy 5454-H32 base metal and 5025 or 5087 filler metals. These filler metals contain zirconium and scandium additions, respectively, and were expected to influence nucleation and growth behavior. Both as-welded and welded/heat treated (540°C and 300°C) substrates were tested by melting simulation, resulting in dendritic and EQZ structures depending on composition and substrate condition. Orientation imaging microscopy (OIM(TM)) was employed to study the crystallographic character of the microstructures produced and to verify the mechanism responsible for EQZ formation. OIM(TM) proved that grains within the EQZ have random orientation. In all other cases, where the simulated microstructures were dendritic in nature, it was shown that epitaxy was the dominant mode of nucleation. The lack of any preferred crystallographic orientation relationship in the EQZ supports a theory proposed by Lippold et al that the EQZ is the result of heterogeneous nucleation within the weld unmixed zone. EDS analysis of the 2195 on STEM revealed particles with ternary composition consisted of Zr, Cu and Al and a tetragonal type crystallographic lattice. Microdiffraction line scans on EQZ grains in the alloy 2195 showed very good agreement between the measured Cu

  15. An improved stress corrosion test medium for aluminum alloys

    NASA Technical Reports Server (NTRS)

    Humphries, T. S.; Coston, J. E.

    1981-01-01

    A laboratory test method that is only mildly corrosive to aluminum and discriminating for use in classifying the stress corrosion cracking resistance of aluminum alloys is presented along with the method used in evaluating the media selected for testing. The proposed medium is easier to prepare and less expensive than substitute ocean water.

  16. Corrosion protection of aluminum alloys in contact with other metals

    NASA Technical Reports Server (NTRS)

    Kuster, C. A.

    1969-01-01

    Study establishes the quality of chemical and galvanized protection afforded by anodized and aldozided coatings applied to test panels of various aluminum alloys. The test panels, placed in firm contact with panels of titanium alloys, were subjected to salt spray tests and visually examined for corrosion effect.

  17. Effects of high frequency current in welding aluminum alloy 6061

    NASA Technical Reports Server (NTRS)

    Fish, R. E.

    1968-01-01

    Uncontrolled high frequency current causes cracking in the heat-affected zone of aluminum alloy 6061 weldments during tungsten inert gas ac welding. Cracking developed when an improperly adjusted superimposed high frequency current was agitating the semimolten metal in the areas of grain boundary.

  18. Tensile Properties of 7075-T6 and 2024-T3 Aluminum-alloy Sheet Heated at Uniform Temperature Rates Under Constant Load

    NASA Technical Reports Server (NTRS)

    Heimerl, George J; Inge, John E

    1955-01-01

    Results are presented of tests to determine the effect of heating at uniform temperature rates from 0.2 degrees to 100 degrees F. per second on the tensile properties of 7075-T6 d(75s-T6) and 2024-T3 (24s-T3) aluminum-alloy sheet under constant-load conditions. Yield and rupture stresses, obtained under rapid-heating conditions, are compared with results of elevated-temperature stress-strain tests for 1/2-hour exposure. Master yield-and-rupture-stress curves based on linear temperature-rate parameter are presented. Yield and rupture stresses and temperatures may be predicted by means of master curves and the parameter.

  19. Design of Tools for Press-countersinking or Dimpling 0.040-inch-thick-24S-T Sheet

    NASA Technical Reports Server (NTRS)

    Templin, R L; Fogwell, J W

    1942-01-01

    A set of dimpling tools was designed for 0.040-inch 24S-T sheet and flush-type rivets 1/8 inch in diameter with 100 degree countersunk heads. The dimples produced under different conditions of pressure, sheet thickness, and drill diameter are presented as cross-sectional photographs magnified 20 times. The most satisfactory values for the dimpling tools were found to be: maximum punch diameter, 0.231 inch; maximum die diameter, 0.223 inch; maximum mandrel diameter, 0.128 inch; dimple angle, 100 degree; punch springback angle, 1 1/2 degree; and die springback angle, 2 degree.

  20. Bending Tests of Circular Cylinders of Corrugated Aluminum-alloy Sheet

    NASA Technical Reports Server (NTRS)

    Buckwalter, John C; Reed, Warren D; Niles, Alfred S

    1937-01-01

    Bending tests were made of two circular cylinders of corrugated aluminum-alloy sheet. In each test failure occurred by bending of the corrugations in a plane normal to the skin. It was found, after analysis of the effect of short end bays, that the computed stress on the extreme fiber of a corrugated cylinder is in excess of that for a flat panel of the same basic pattern and panel length tested as a pin-ended column. It is concluded that this increased strength was due to the effects of curvature of the pitch line. It is also concluded from the tests that light bulkheads closely spaced strengthen corrugated cylinders very materially.

  1. Calcium metal as a scavenger for antimony from aluminum alloys

    SciTech Connect

    Bonsignore, P.V.; Daniels, E.J.; Wu, C.T.

    1994-10-04

    Previous work has shown that trace amounts of antimony (Sb) can affect the mechanical properties of strontium (Sr) modified aluminum castings. ANL has been investigating technology to remove or neutralize Sb to reduce its negative effect on the physical properties of those alloys. Review of past work on processing and recovery of scrap aluminum inferred that calcium (Ca) is an effective scavenger of Sb, bismuth, lead and cadmium. Following up on that lead, we have found that Ca is, indeed, effective for removing Sb from molten aluminum alloys although its effectiveness can be compromised by a wide range of processing conditions. A minimum ratio of about four to one, by weight, of Ca to Sb appears necessary to insure an effective scavenging of contained Sb.in 356 aluminum alloys.

  2. Preparation of cast aluminum alloy-mica particle composites

    NASA Technical Reports Server (NTRS)

    Deonath, MR.; Bhat, R. T.; Rohatgi, P. K.

    1980-01-01

    A method for making aluminum-mica particle composites is presented in which mica particles are stirred in molten aluminum alloys followed by casting in permanent molds. Magnesium is added either as an alloying element or in the form of pieces to the surface of the alloy melts to disperse up to 3 wt% mica powders in the melts and to obtain high recoveries of mica in the castings. The mechanical properties of the aluminum alloy-mica composite decrease with increasing mica content; however, even at 2.2% it has a tensile strength of 14.22 kg/sq mm with 1.1% elongation, a compression strength of 42.61 kg/sq mm, and an impact strength of 0.30 kgm/sq cm. Cryogenic and self-lubricating bearing are mentioned applications.

  3. Corrosion Behavior of Aluminum Alloys in Acidic Media

    SciTech Connect

    Ramli, Rosliza; Seoh, S. Y.; Nik, W. B. Wan; Senin, H. B.

    2007-05-09

    The corrosion inhibition of Al and its alloys are the subject of tremendous technological importance due to the increased industrial applications of these materials. This study will report the results of weight loss, polarization and electrochemical impedance spectroscopic (EIS) measurements on the corrosion inhibition of AA6061 and AA6063 aluminum alloys in acidic media using sodium benzoate as an inhibitor. The results showed that addition of sodium benzoate retards the rate of dissolution and hence inhibits the corrosion of the aluminum alloy in acidic media. The inhibition efficiency increases with the increase of immersion time in acetic acid however it displays a different behavior in sulfuric acid. Langmuir adsorption isotherm fits well with the experimental data. EIS studies showed that there was a significant increase in overall resistance after addition of sodium benzoate, when compared to the case without inhibitor. Langmuir adsorption isotherm fits well with the experimental data.

  4. Grain size control and superplasticity in 6013-type aluminum alloys

    NASA Astrophysics Data System (ADS)

    Troeger, Lillianne Plaster Whitelock

    Aluminum alloys have been the material of choice for aircraft construction since the 1930's. Currently, the automotive industry is also showing an increasing interest in aluminum alloys as structural materials. 6xxx aluminum alloys possess a combination of strength and formability which makes them attractive to both industries. In addition, 6xxx alloys are highly weldable, corrosion resistant, and low in cost as compared with the 2xxx and 7xxx aluminum alloys. Superplastic forming (SPF) is a manufacturing process which exploits the phenomenon of superplasticity in which gas pressure is used to form complex-shaped parts in a single forming operation. This reduces part counts and the need for fasteners and connectors, resulting in reduced product weight. Reduced product/vehicle weight improves fuel economy. Most alloys must be specially processed for superplasticity. Much research effort has been directed at the development of thermomechanical processes for the grain refinement of aluminum alloys by static or dynamic recrystallization. to induce superplasticity. While large numbers of studies have been conducted on 2xxx, 5xxx, 7xxx, and 8xxx aluminum alloys, very few studies have been focused on the grain refinement of 6xxx aluminum alloys for superplasticity. The current research describes a new thermomechanical process for application to 6xxx aluminum alloys for grain refinement and superplasticity. The process is shown to successfully refine and induce superplasticity in an Al-Mg-Si-Cu alloy which falls within the compositional limits of both 6013 and 6111. The grain refinement is by particle-stimulated nucleation of recrystallization. The microstructural evolution during the thermomechanical processing is characterized in terms of precipitate size, shape, distribution and composition; texture; recrystallization; and grain size, shape, and thermal stability. The new process produces a statically-stable, weakly-textured, equiaxed grain structure with an average

  5. Fabrication of superhydrophobic nanostructured surface on aluminum alloy

    NASA Astrophysics Data System (ADS)

    Jafari, R.; Farzaneh, M.

    2011-01-01

    A superhydrophobic surface was prepared by consecutive immersion in boiling water and sputtering of polytetrafluoroethylene (PTFE or Teflon®) on the surface of an aluminum alloy substrate. Immersion in boiling water was used to create a micro-nanostructure on the alloy substrate. Then, the rough surface was coated with RF-sputtered Teflon film. The immersion time in boiling water plays an important role in surface morphology and water repellency of the deposited Teflon coating. Scanning electron microscopy images showed a "flower-like" structure in first few minutes of immersion. And as the immersion time lengthened, a "cornflake" structure appeared. FTIR analyses of Teflon-like coating deposited on water treated aluminum alloy surfaces showed fluorinated groups, which effectively reduce surface energy. The Teflon-like coating deposited on a rough surface achieved with five-minute immersion in boiling water provided a high static contact angle (˜164°) and low contact angle hysteresis (˜4°).

  6. Laser welding of aeronautical and automobile aluminum alloys

    NASA Astrophysics Data System (ADS)

    Boukha, Z.; Sánchez-Amaya, J. M.; Amaya-Vázquez, M. R.; González-Rovira, L.; Botana, F. J.

    2012-04-01

    Laser beam welding (LBW) show clear advantages compared with other techniques, as the low heat input, the high localization ability, the high welding speed, the high flexibility, the high weld quality and the high production rate. However, its applicability to aluminum alloys is limited, as they generally have high reflectivity, high thermal conductivity and low viscosity. In the present study, it is analyzed the laser weldability of four aluminum alloys (2024, 5083, 6082 and 7075). High penetration butt welds could be obtained with a high power diode laser under conduction regime. The properties of the weld beads such as the microstructure and microhardness were analyzed. A linear function between the input laser fluence and the volume of melted material was obtained for the four alloys.

  7. Materials data handbook: Aluminum alloy 2014, 2nd edition

    NASA Technical Reports Server (NTRS)

    Muraca, R. F.; Whittick, J. S.

    1972-01-01

    A revised edition of the materials data handbook on the aluminum alloy 2014 is presented. The scope of the information presented includes physical and mechanical property data at cryogenic, ambient and elevated temperatures, supplemented with useful information in such areas as material procurement, metallurgy of the alloy, corrosion, environmental effects, fabrication and joining techniques. Design data are presented, as available, and these data are complemented with information on the typical behavior of the alloy.

  8. 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.

  9. Linear Anomaly in Welded 2219-T87 Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Jemian, Wartan A.

    1987-01-01

    Study of causes and significance of two types of linear anomalies sometimes appearing in radiographs of welds described in preliminary report. Manifested as light or dark linear features parallel to weld line in radiograph of weld. Contains diagrams and descriptions of phenomena occurring during welding process. Includes microdensitometer traces from x-radiographs of actual welds and from computer simulations based calculation of x-ray transmission through assumed weld structures. Concludes anomalies not unique to 2219-T87 aluminum alloy.

  10. Fatigue-Crack Propagation in Aluminum-Alloy Tension Panels

    NASA Technical Reports Server (NTRS)

    Whaley, Richard E.; Kurzhals, Peter R.

    1960-01-01

    Results are presented of a series of fatigue tests to study crack propagation and the resulting stress distributions in tension panels. The panels were all of the same general design, and configurations varied mainly in the relative amount of cross-sectional area in the skin, stiffeners, and flanges. The panels were constructed of 2024-T3 and 7075-T6 aluminum alloys. It was found that the average rate of crack growth was slower in panels made of 2024-T3 aluminum alloy than in panels made of 7075-T6 aluminum alloy. All cracks initiated in the skin, and the slowest crack growth was measured in configurations where the highest percentage of cross-sectional area was in the stiffeners. Strain-gage surveys were made to determine the redistribution of stress as the crack grew across the panels. As a crack approached a given point in the skin, the stress at that point increased rapidly. The stress in the stiffeners also increased as the crack approached the stiffeners. During the propagation of the crack the stress was not distributed uniformly in the remaining area.

  11. High Strength Aluminum Alloy For High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2005-01-01

    A cast article from an aluminum alloy has improved mechanical properties at elevated temperatures. The cast article has the following composition in weight percent: Silicon 6.0-25.0, Copper 5.0-8.0, Iron 0.05-1.2, Magnesium 0.5-1.5, Nickel 0.05-0.9, Manganese 0.05-1.2, Titanium 0.05-1.2, Zirconium 0.05-1.2, Vanadium 0.05-1.2, Zinc 0.05-0.9, Strontium 0.001-0.1, Phosphorus 0.001-0.1, and the balance is Aluminum, wherein the silicon-to-magnesium ratio is 10-25, and the copper-to-magnesium ratio is 4-15. The aluminum alloy contains a simultaneous dispersion of three types of Al3X compound particles (X=Ti, V, Zr) having a LI2 crystal structure, and their lattice parameters are coherent to the aluminum matrix lattice. A process for producing this cast article is also disclosed, as well as a metal matrix composite, which includes the aluminum alloy serving as a matrix containing up to about 60% by volume of a secondary filler material.

  12. Tensile and impact properties of iron-aluminum alloys

    SciTech Connect

    Alexander, D.J.; Sikka, V.K.

    1993-12-31

    Tensile and impact tests have been conducted on specimens from a series of five heats of iron-aluminum alloys. These results have been compared to data for the iron aluminide alloy FA-129. The transition temperatures of all of the Fe{sub 3}Al-based alloys were similar, but the simple ternary alloy had a much higher upper-shelf energy. The reduced aluminum alloys [based on Fe-8Al (wt %)] had lower transition temperatures and higher upper-shelf energy levels than the Fe{sub 3}Al-type alloys. The reduced aluminum alloy with yttrium showed excellent tensile properties, with a room temperature total elongation of 40%, and a very high upper-shelf energy level. Despite the high tensile ductility at room temperature, the transition temperature of the yttrium-containing alloy was still about 150 C, compared to approximately 300 C for FA-129. In general, the microstructures were coarse and anisotropic. The fracture processes were dominated by second-phase particles.

  13. Tensile and pack compressive tests of some sheets of aluminum alloy, 1025 carbon steel, and chromium-nickel steel

    NASA Technical Reports Server (NTRS)

    Atchison, C S; Miller, James A

    1942-01-01

    Tensile and compressive stress-strain curves, stress-deviation curves, and secant modulus-stress curves are given for longitudinal and transverse specimens of 17S-T, 24S-T, and 24S-RT aluminum-alloy sheet in thicknesses from 0.032 to 0.081 inch, 1025 carbon steel sheet in thicknesses of 0.054 and 0.120 inch, and chromium-nickel steel sheet in thicknesses form 0.020 to 0.0275 inch. Significant differences were found between the tensile and the compressive stress-strain curves, and also the corresponding corollary curves; similarly, differences were found between the curves for the longitudinal and transverse directions. These differences are of particular importance in considering the compressive strength of aircraft structures made of thin sheet. They are explored further for the case of compression by giving tangent modulus-stress curves in longitudinal and transverse compression and dimensionless curves of the ratio of tangent modulus to Young's modulus and of the ratio of reduced modulus for a rectangular section to Young's modulus, both plotted against the ratio of stress to secant yield strength.

  14. Effect of vapor phase corrosion inhibitor on microbial corrosion of aluminum alloys.

    PubMed

    Yang, S S; Ku, C H; Bor, H J; Lin, Y T

    1996-02-01

    Vapor phase corrosion inhibitors were used to investigate the antimicrobial activities and anticorrosion of aluminum alloy. Aspergillus flavus, A. niger, A. versicolor, Chaetomium globosum and Penicillium funiculosum had moderate to abundant growth on the aluminum alloy AA 1100 at Aw 0.901, while there was less growth at Aw 0.842. High humidity stimulated microbial growth and induced microbial corrosion. Dicyclohexylammonium carbonate had a high inhibitory effect on the growth of test fungi and the microbial corrosion of aluminum alloy, dicyclohexylammonium caprate and dicyclohexylammonium stearate were the next. Aluminum alloy coating with vapor phase corrosion inhibitor could prevent microbial growth and retard microbial corrosion. PMID:10592784

  15. Optimization of Squeeze Casting for Aluminum Alloy Parts

    SciTech Connect

    David Schwam; John F. Wallace; Qingming Chang; Yulong Zhu

    2002-07-30

    This study was initiated with the installation of a new production size UBE 350 Ton VSC Squeeze Casting system in the Metal Casting Laboratory at Case Western University. A Lindberg 75k W electrical melting furnace was installed alongside. The challenge of installation and operation of such industrial-size equipment in an academic environment was met successfully. Subsequently, a Sterling oil die heater and a Visi-Track shot monitoring system were added. A significant number of inserts were designed and fabricated over the span of the project, primarily for squeeze casting different configurations of test bars and plates. A spiral ''ribbon insert'' for evaluation of molten metal fluidity was also fabricated. These inserts were used to generate a broad range of processing conditions and determine their effect on the quality of the squeeze cast parts. This investigation has studied the influence of the various casting variables on the quality of indirect squeeze castings primarily of aluminum alloys. The variables studied include gating design, fill time and fill patter, metal pressure and die temperature variations. The quality of the die casting was assessed by an analysis of both their surface condition and internal soundness. The primary metal tested was an aluminum 356 alloy. In addition to determining the effect of these casting variables on casting quality as measured by a flat plate die of various thickness, a number of test bar inserts with different gating designs have been inserted in the squeeze casting machine. The mechanical properties of these test bars produced under different squeeze casting conditions were measured and reported. The investigation of the resulting properties also included an analysis of the microstructure of the squeeze castings and the effect of the various structural constituents on the resulting properties. The main conclusions from this investigation are as follows: The ingate size and shape are very important since it must

  16. Microstructural issues in a friction-stir-welded aluminum alloy

    SciTech Connect

    Flores, O.V.; Kennedy, C.; Murr, L.E.; Brown, D.; Pappu, S.; Nowak, B.M.; McClure, J.C.

    1998-02-03

    Recent observations of microstructures associated with friction-stir welding (FSW) in a number of aluminum alloys have consistently demonstrated the actual weld zone to consist of a (dynamically) recrystallized grain structure resulting from the extreme, solid-state, plastic deformation characterizing the process. Because of solubilities associated with the various precipitates in 7075 and 6061 aluminum alloys, and the fact that the precipitates were either homogeneously distributed throughout both the original (unwelded) work-piece plates and the well zones (or formed varying densities of Widmanstaetten patterns within the original and recrystallized grains), it has been difficult to follow the stirring of stable, second-phase particles from the base metal (work-piece) into the weld zone. In the present investigation, a compositionally modified 1100 aluminum alloy (nominally 99.2% Al, 0.5% Fe, 0.15% Cu, 0.12% Si, 0.05 Mn, 0.04 Ti, balance in weight percent of Be and Mg), forming a stable microdendritic (second-phase), equiaxed, cell structure was friction-stir welded. These thermally stable, geometrically specific, precipitates in the base metal were compared with their disposition within the friction-stir-weld zone. In addition, as-cast plates of this alloy were cold-rolled 50% and friction-stir-welded in order to compare these two schedules (as-cast and 50% cold-rolled) in terms of residual hardness variations and related microstructural issues as well as the effect of prior deformation on the friction-stir welding process.

  17. Conducting polymers and corrosion: Part 2 -- Polyaniline on aluminum alloys

    SciTech Connect

    Tallman, D.E.; Pae, Y.; Bierwagen, G.P.

    2000-04-01

    The electrochemical behavior of conducting polyaniline coatings on various aluminum alloys subjected to immersion in dilute Harrison solution (0.35% ammonium sulfate [(NH{sub 4}){sub 2}SO{sub 4}], 0.05% sodium chloride [NaCl]) was studied. Electrochemical impedance spectroscopy revealed that the charge-transfer resistance (R{sub ct}) of polyaniline-coated alloys increased as a function of immersion time. Polyaniline-coated platinum did not exhibit a significant increase in impedance under similar conditions, indicating that an active metal in contact with the polyaniline is required for the observed increase in R{sub ct}. A similar pattern of increasing R{sub ct} was observed for Alodine (Product A)-treated Al 7075T-6 (UNS A97075) alloys. Mean current and mean potential values obtained from electrochemical noise measurements also suggest a substantial electrochemical interaction between the polyaniline and the aluminum alloy during the early stages of immersion. Polarization experiments and open-circuit potential measurements revealed an ennobling of aluminum alloys to higher potential in the presence of polyaniline coatings. The corrosion protection afforded by a polyaniline/epoxy two-coat system on Al 2024T-3 (UNS A92024) alloy also was evaluated using impedance spectroscopy and compared with that for a single coat of epoxy on untreated and Product A-treated Al2024T-3 alloy. The Product A treatment and the polyaniline coating were found to increase the lifetime of the epoxy topcoat, although these two-coating systems exhibited rather different variations in low-frequency impedance with immersion time. A mechanism consistent with these observations was suggested.

  18. FRICTION STIR SPOT WELDING OF 6016 ALUMINUM ALLOY

    SciTech Connect

    Mishra, Rajiv S.; Webb, S.; Freeney, T. A.; Chen, Y. L.; Gayden, X.; Grant, Glenn J.; Herling, Darrell R.

    2007-01-08

    Friction stir spot welding (FSSW) of 6016 aluminum alloy was evaluated with conventional pin tool and new off-center feature tools. The off-center feature tool provides significant control over the joint area. The tool rotation rate was varied between 1000 and 2500 rpm. Maximum failure strength was observed in the tool rotation range of 1200-1500 rpm. The results are interpreted in the context of material flow in the joint and influence of thermal input on microstructural changes. The off-center feature tool concept opens up new possibilities for plunge-type friction stir spot welding.

  19. Electrodeposition of magnesium and magnesium/aluminum alloys

    DOEpatents

    Mayer, A.

    1988-01-21

    Electrolytes and plating solutions for use in processes for electroplating and electroforming pure magnesium and alloys of aluminum and magnesium and also electrodeposition processes. An electrolyte of this invention is comprised of an alkali metal fluoride or a quaternary ammonium halide, dimethyl magnesium and/or diethyl magnesium, and triethyl aluminum and/or triisobutyl aluminum. An electrolyte may be dissolved in an aromatic hydrocarbon solvent to form a plating solution. The proportions of the component compounds in the electrolyte are varied to produce essentially pure magnesium or magnesium/aluminum alloys having varying selected compositions.

  20. Electrodeposition of magnesium and magnesium/aluminum alloys

    DOEpatents

    Mayer, Anton

    1988-01-01

    Electrolytes and plating solutions for use in processes for electroplating and electroforming pure magnesium and alloys of aluminum and magnesium and also electrodeposition processes. An electrolyte of this invention is comprised of an alkali metal fluoride or a quaternary ammonium halide, dimethyl magnesium and/or diethyl magnesium, and triethyl aluminum and/or triisobutyl aluminum. An electrolyte may be dissolved in an aromatic hydrocarbon solvent to form a plating solution. The proportions of the component compounds in the electrolyte are varied to produce essentially pure magnesium or magnesium/aluminum alloys having varying selected compositions.

  1. Outgassing measurement of the aluminum alloy UHV chamber

    NASA Technical Reports Server (NTRS)

    Miyamoto, M.; Itoh, T.; Komaki, S.; Narushima, K.; Ishimaru, H.

    1986-01-01

    A large vacuum chamber (580 mm diameter) was fabricated from an aluminum alloy surface treated by a special process normally used on small chambers. The chamber was tested unbaked and baked at various temperatures, pressures, and holding periods. The chamber was filled with N2 gas, and the outgassing rate was measured after one hour. Then the ultimate pressure was measured. Outgassing rates for baked and unbaked groups were compared. It is concluded that the same surface treatment technique can be used on both large and small chambers produced by the same special extrusion process.

  2. Hot corrosion resistance of nickel-chromium-aluminum alloys

    NASA Technical Reports Server (NTRS)

    Santoro, G. J.; Barrett, C. A.

    1977-01-01

    The hot corrosion resistance of nickel-chromium-aluminum alloy was examined by cyclically oxidizing sodium sulfate coated specimens in still air at 900, 1000 and 1100 C. The compositions tested were within the ternary region: Ni; Ni-50 at.% Cr; and Ni-50 at.% Al. At each temperature the corrosion data were statistically fitted to a third order regression equation as a function of chromium and aluminum contents. Corrosion isopleths were prepared from these equations. Compositional regions with the best hot corrosion resistance were identified.

  3. Corrosion fatigue of 2219-T87 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Mcmillan, V. C.

    1986-01-01

    Corrosion fatigue studies were conducted on bare, chemical conversion coated, and anodized 2219-T87 aluminum alloy. These tests were performed using a rotating beam machine running at a velocity of 2500 rpm. The corrosive environments tested were distilled water, 100 ppm NaCl, and 3.5 percent NaCl. Results were compared to the endurance limit in air. An evaluation of the effect of protective coatings on corrosion fatigue was made by comparing the fatigue properties of specimens with coatings to those without.

  4. Microstructural and superplastic characteristics of friction stir processed aluminum alloys

    NASA Astrophysics Data System (ADS)

    Charit, Indrajit

    Friction stir processing (FSP) is an adapted version of friction stir welding (FSW), which was invented at The Welding Institute (TWI), 1991. It is a promising solid state processing tool for microstructural modification at localized scale. Dynamic recrystallization occurs during FSP resulting in fine grained microstructure. The main goal of this research was to establish microstructure/superplasticity relationships in FSP aluminum alloys. Different aluminum alloys (5083 Al, 2024 Al, and Al-8.9Zn-2.6Mg-0.09Sc) were friction stir processed for investigating the effect of alloy chemistry on resulting superplasticity. Tool rotation rate and traverse speeds were controlled as the prime FSP parameters to produce different microstructures. In another study, lap joints of 7475 Al plates were also studied to explore the possibility of developing FSW/superplastic forming route. Microstructures were evaluated using optical, scanning and transmission electron microscopy, orientation imaging microscopy and differential scanning calorimetry. Mechanical properties were evaluated using tensile testing. FSP 2024 Al (3.9 mum grain size) exhibited an optimum ductility of 525% at a strain rate of 10-2 s-1 and 430°C. Grain boundary sliding mechanism was found to be the dominant mode of deformation in this alloy. In 5083 Al alloy, it was found that changing the process parameters, grain sizes in the range of 3.5--8.5 mum grain size could be obtained. Material processed with colder processing parameters showed a decrease in ductility due to microstructural instability, and followed solute drag dislocation glide mechanism. On the other hand, materials processed with hotter parameter combinations showed mode of deformation related to grain boundary sliding mechanism. FSP of as-cast Al-Zn-Mg-Sc alloy resulted in ultrafine grains (0.68 mum) with attractive combination of high strain rate and low temperature superplasticity. This also demonstrated that superplastic microstructures could be

  5. Ion implantation and diamond-like coatings of aluminum alloys

    SciTech Connect

    Malaczynski, G.W.; Hamdi, A.H.; Elmoursi, A.A.; Qiu, X.

    1997-04-01

    In an attempt to increase the wear resistance of some key automotive components, General Motors Research and Development Center initiated a study to determine the potential of surface modification as a means of improving the tribological properties of automotive parts, and to investigate the feasibility of mass producing such parts. This paper describes the plasma immersion ion implantation system that was designed for the study of various options for surface treatment, and it discusses bench testing procedures used for evaluating the surface-treated samples. In particular, both tribological and microstructural analyses are discussed for nitrogen implants and diamond-like hydrocarbon coatings of some aluminum alloys.

  6. An investigation of plastic fracture in aluminum alloys

    NASA Technical Reports Server (NTRS)

    Low, J. R., Jr.; Vanstone, R. H.; Merchant, R. H.

    1972-01-01

    The brittle fracture of many high strength alloys such as steel, titanium, and aluminum was shown to occur by a process called plastic fracture. According to this process microscopic voids form at impurity particles, then grow and coalesce to cause the final rupture. To further understand the role of impurities, four aluminum alloys were investigated: 2024-T851, 2124-T851, 7075-T7351 and 7079-T651. Fractography, quantitative metallography, and microprobe studies assessed the roles of various impurity particles relative to these alloys.

  7. Effects of Machining on the Microstructure of Aluminum Alloy 7075

    NASA Astrophysics Data System (ADS)

    Tabei, A.; Liang, S. Y.; Garmestani, H.

    Experimental investigations show that depending on the parameters, aggressive machining of aluminum alloy 7075 can trigger several microstructural phenomena including recrystallization, grain growth and crystallographic texture modifications below the machined surface. Increasing the depth of cut will lead to a significant recrystallization and consequently grain refinement. On the other hand, increasing the feed rate will result into development of a unique crystallographic texture. The mechanical and thermal loads imposed to the material experiences by machining leads to such microstructural phenomena. Finite element analysis is used to determine these loads.

  8. Stress corrosion in high-strength aluminum alloys

    NASA Technical Reports Server (NTRS)

    Dorward, R. C.; Hasse, K. R.

    1980-01-01

    Report describes results of stress-corrosion tests on aluminum alloys 7075, 7475, 7050, and 7049. Tests compare performance of original stress-corrosion-resistant (SCR) aluminum, 7075, with newer, higher-strength SCR alloys. Alloys 7050 and 7049 are found superior in short-transverse cross-corrosion resistance to older 7075 alloy; all alloys are subject to self-loading effect caused by wedging of corrosion products in cracks. Effect causes cracks to continue to grow, even at very-low externally applied loads.

  9. Overcoming residual stresses and machining distortion in the production of aluminum alloy satellite boxes.

    SciTech Connect

    Younger, Mandy S.; Eckelmeyer, Kenneth Hall

    2007-11-01

    Distortion frequently occurs during machining of age hardening aluminum alloys due to residual stresses introduced during the quenching step in the heat treatment process. This report quantifies, compares, and discusses the effectiveness of several methods for minimizing residual stresses and machining distortion in aluminum alloys 7075 and 6061.

  10. Cast B2-phase iron-aluminum alloys with improved fluidity

    DOEpatents

    Maziasz, Philip J.; Paris, Alan M.; Vought, Joseph D.

    2002-01-01

    Systems and methods are described for iron aluminum alloys. A composition includes iron, aluminum and manganese. A method includes providing an alloy including iron, aluminum and manganese; and processing the alloy. The systems and methods provide advantages because additions of manganese to iron aluminum alloys dramatically increase the fluidity of the alloys prior to solidification during casting.

  11. Dynamic response of two strain-hardened aluminum alloys

    NASA Astrophysics Data System (ADS)

    Boteler, J. M.; Dandekar, D. P.

    2006-09-01

    Despite their common usage in armor applications such as lightweight armored vehicles, the dynamic material response of 5083-H131 and 5083-H32 strain-hardened aluminum alloys has not been previously reported in the open literature. Measurement of the dynamic material properties, including the shock Hugoniot equation of state (EOS), provides hydrocode modelers with critical information required for accurate modeling of material response to intense loading. In the work reported here we investigate the Hugoniot EOS and Hugoniot elastic limit over the stress range of 1.5-8.0GPa. All experiments were performed on the Army Research Laboratory 102mm bore single-stage light gas gun. Impact conditions were uniaxial and planar to within 1mrad of tilt. Both direct-impact- and shock-transmission-type experiments were performed using velocity interferometry diagnostics to record particle velocity histories with 0.5ns temporal resolution. The shock Hugoniot for 5083-H131 is extrapolated to 50GPa and compared to the previous high pressure results of Hauver and Melani (1973) [Ballistic Research Laboratory December Technical Report No. BRL 2345, 1973] and to prior shock studies of 5083-O aluminum alloy.

  12. Electrochemical noise measurements during exfoliation of aluminum alloys

    SciTech Connect

    Damborenea, J. de; Fernandez, B.

    1996-12-31

    Aluminum alloys are one of the most widely used materials in the aerospace industry because of their intrinsic low density, high mechanical strength, and corrosion resistance. The performance of aircraft is improved by the use of lighter materials. Electrochemical noise measurements (ENMs) have been carried out during exfoliation corrosion of an aluminum-lithium alloy (8090) in the EXCO (ASTM Test Method for Exfoliation Corrosion Susceptibility in 2XXX and 7XXX Series Aluminum Alloys [EXCO Test] [G 34]) test solution. By means of the maximum entropy method (MEM), the potential and current fluctuations were converted into power spectral density (PSD) plots to study the specific variables related to electrochemical noise (low frequency amplitude, slopes). Noise resistance obtained from the standard deviation of potential and current was compared with the charge transference resistance (R{sub ct}) from electrochemical impedance spectroscopy (EIS) measurements. The results show that ENM can be used to detect early stages in localized corrosion. However, when the solution is very aggressive, indications of localized corrosion can be masked by uniform corrosion.

  13. Direct-soldering 6061 aluminum alloys with ultrasonic coating.

    PubMed

    Ding, Min; Zhang, Pei-lei; Zhang, Zhen-yu; Yao, Shun

    2010-02-01

    In this study, the authors applied furnace soldering with ultrasonic coating method to solder 6061 aluminum alloy and investigated the effects of both coating time and soldering temperature on its properties. The following results were obtained: firstly, the solder region mainly composed of four kinds of microstructure zones: rich Sn zone, rich-Pb zone, Sn-Pb eutectic phase and rich Al zone. Meanwhile, the microanalysis identified a continuous reaction product at the alumina-solder interface as a rich-Pb zone. Therefore, the joint strength changed with soldering time and soldering temperature. Secondly, the tensile data had significantly greater variability, with values ranging from 13.99MPa to 24.74MPa. The highest value was obtained for the samples coated with Sn-Pb-Zn alloy for 45s. Fractures occurred along the solder-alumina interface for the 6061 aluminum alloy with its surface including hybrid tough fracture of dimple and tear ridge. The interface could initially strip at the rich Bi zone with the effect of shear stress. PMID:19900830

  14. Conversion Coatings for Aluminum Alloys by Chemical Vapor Deposition Mechanisms

    NASA Technical Reports Server (NTRS)

    Reye, John T.; McFadden, Lisa S.; Gatica, Jorge E.; Morales, Wilfredo

    2004-01-01

    With the rise of environmental awareness and the renewed importance of environmentally friendly processes, the United States Environmental Protection Agency has targeted surface pre-treatment processes based on chromates. Indeed, this process has been subject to regulations under the Clean Water Act as well as other environmental initiatives, and there is today a marked movement to phase the process out in the near future. Therefore, there is a clear need for new advances in coating technology that could provide practical options for replacing present industrial practices. Depending on the final application, such coatings might be required to be resistant to corrosion, act as chemically resistant coatings, or both. This research examined a chemical vapor deposition (CVD) mechanism to deposit uniform conversion coatings onto aluminum alloy substrates. Robust protocols based on solutions of aryl phosphate ester and multi-oxide conversion coating (submicron) films were successfully grown onto the aluminum alloy samples. These films were characterized by X-ray Photoelectron Spectroscopy (XPS). Preliminary results indicate the potential of this technology to replace aqueous-based chromate processes.

  15. 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

  16. Transverse flux induction heating of aluminum alloy strip

    NASA Astrophysics Data System (ADS)

    Waggott, R.; Walker, D. J.; Gibson, R. C.; Johnson, R. C.

    1981-07-01

    Transverse flux induction heating, an efficient electrical technique particularly suited to the continuous heat treatment of metal strip, is explained. Also described is a 1MW transverse flux inductor designed and built at the Electricity Council Research Centre, Capenhurst, and installed in a tension leveller line at Alcan Plate Ltd., Birmingham, UK. It has been successfully used for the continuous heat treatment of wide (1200-1250 mm) aluminum alloy strip, involving full and partial annealing at line speeds up to 2/ms as well as the solution treatment of certain high strength aluminum alloys. The advantages of this form of induction heating are compactness, controllability, hence ease of automation, and high efficiency. As a consequence, compared with existing batch and continuous heat treatment equipment, major economies in plant operation result due to reduced energy consumption as well as reduced capital and labor costs. The compactness of the technique allows the possibility of introducing transverse flux induction heat treatment furnaces into existing process lines.

  17. Laser shocking of 2024 and 7075 aluminum alloys

    NASA Technical Reports Server (NTRS)

    Clauer, A. H.; Fairand, B. P.; Slater, J. E.

    1977-01-01

    The effect of laser generated stress waves on the microstructure, hardness, strength and stress corrosion resistance of 2024 and 7075 aluminum alloys was investigated. Pulsed CO2 and neodymium-glass lasers were used to determine the effect of wavelength and pulse duration on pressure generation and material property changes. No changes in material properties were observed with CO2 laser. The strength and hardness of 2024-T351 and the strength of 7075-T73 aluminum alloys were substantially improved by the stress wave environments generated with the neodymium-glass laser. The mechanical properties of 2024-T851 and 7075-T651 were unchanged by the laser treatment. The correlation of the laser shock data with published results of flyer plate experiments demonstrated that a threshold pressure needed to be exceeded before strengthening and hardening could occur. Peak pressures generated by the pulsed laser source were less than 7.0 GPa which was below the threshold pressure required to change the mechanical properties of 2024-T851 and 7075-T651. Corrosion studies indicated that laser shocking increased the resistance to local attack in 2024-T351 and 7075-T651.

  18. Mechanical properties of anodized coatings over molten aluminum alloy.

    PubMed

    Grillet, Anne M; Gorby, Allen D; Trujillo, Steven M; Grant, Richard P; Hodges, V Carter; Parson, Ted B; Grasser, Thomas W

    2008-01-01

    A method to measure interfacial mechanical properties at high temperatures and in a controlled atmosphere has been developed to study anodized aluminum surface coatings at temperatures where the interior aluminum alloy is molten. This is the first time that the coating strength has been studied under these conditions. We have investigated the effects of ambient atmosphere, temperature, and surface finish on coating strength for samples of aluminum alloy 7075. Surprisingly, the effective Young's modulus or strength of the coating when tested in air was twice as high as when samples were tested in an inert nitrogen or argon atmosphere. Additionally, the effective Young's modulus of the anodized coating increased with temperature in an air atmosphere but was independent of temperature in an inert atmosphere. The effect of surface finish was also examined. Sandblasting the surface prior to anodization was found to increase the strength of the anodized coating with the greatest enhancement noted for a nitrogen atmosphere. Machining marks were not found to significantly affect the strength. PMID:17945243

  19. Degradation Modeling of 2024 Aluminum Alloy During Corrosion Process

    NASA Astrophysics Data System (ADS)

    Pidaparti, Ramana M.; Aghazadeh, Babak Seyed

    2011-04-01

    Corrosion is one of the most damaging mechanisms in aluminum alloys used in aerospace engineering structures. In this article, the degradation behavior of AA 2024-T3 as a function of time under corrosive conditions is studied through experiments and modeling. Corrosion experiments were conducted on AA 2024-T3 specimens under controlled electrochemical conditions. The chemical element alloy map was investigated through EDS technique for evaluation purposes. Based on the experimental data, an analytical model is developed relating the material loss to the degradation during the corrosion process. The analytical model uses genetic algorithms (GAs) to map the relationship through optimization. The results obtained from GAs were compared with a standard non-linear regression model. The results obtained indicate that a quadratic relationship exists in time between the material loss due to corrosion and the degradation behavior of the alloy. Based on the good results obtained, the present approach of degradation modeling can be extended to other metals.

  20. Solid-state Bonding of Superplastic Aluminum Alloy 7475 Sheet

    NASA Technical Reports Server (NTRS)

    Byun, T. D. S.; Vastava, R. B.

    1985-01-01

    Experimental works were carried out to study the feasibility of solid state bonding of superplastic aluminum 7475 sheet. Amount of deformation, bonding time, surface cleaning method and intermediate layer were the process parameters investigated. Other parameters, held constant by the superplastic forming condition which is required to obtain a concurrent solid state bonding, are bonding temperature, bonding pressure and atmosphere. Bond integrity was evaluated through metallographic examination, X-ray line scan analysis, SEM fractographic analysis and lap shear tests. The early results of the development program indicated that sound solid state bonding was accomplished for this high strength 7475 alloy with significant amounts of deformation. A thin intermediate layer of the soft 5052 aluminum alloy aided in achieving a solid state bonding by reducing the required amount of plastic deformation at the interface. Bond strength was substantially increased by a post bond heat treatment.

  1. The Surface Tension of Pure Aluminum and Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Bainbridge, Ian Frank; Taylor, John Andrew

    2013-08-01

    The surface tension of high purity and commercial purity aluminum in vacuo was determined using the sessile drop method and the results were found to compare favorably with published data. The effects of holding atmosphere, substrate, and "surface fracture" of the sessile drop on the measured surface tension values were investigated together with the effects of different solute elements commonly present in commercial aluminum alloys. The results obtained suggest that the nature of the surface oxide film formed on the droplets (affected by alloy composition and atmosphere) and the rupture of this film are the dominant factors influencing the surface tension values obtained. Changes in surface tension values of up to 60 pct were observed. The possible effect of this variable surface tension on practical casting processes, such as direct chill casting, is suggested.

  2. Elevated temperature fracture of RS/PM aluminum alloy 8009

    NASA Technical Reports Server (NTRS)

    Porr, William C., Jr.; Yang, Leng; Gangloff, Richard P.

    1991-01-01

    The fracture behavior of advanced powder metallurgy Al-Fe-V-Si alloy 8009 (previously called FVS0812) is being characterized under monotonic loads, as a function of temperature. Particular attention is focused on contributions to the fracture mechanism from the fine grained dispersoid strengthened microstructure, dissolved solute from rapid solidification, and the moist air environment. Time-dependent crack growth is characterized in advanced aluminum alloys at elevated temperatures with the fracture mechanics approach, and cracking mechanisms are examined with a metallurgical approach. Specific tasks were to obtain standard load crack growth experimental information from a refined testing system; to correlate crack growth kinetics with the j-integral and time dependent C(sub t)(t); and to investigate the intermediate temperature embrittlement of 8009 alloy in order to understand crack growth mechanisms.

  3. The Weathering of Aluminum Alloy Sheet Materials Used in Aircraft

    NASA Technical Reports Server (NTRS)

    Mutchler, Willard

    1935-01-01

    This report presents the results of an investigation of the corrosion of aluminum alloy sheet materials used in aircraft. It has for its purpose to study the causes of corrosion embrittlement in duralumin-type alloys and the development of methods for its elimination. The report contains results, obtained in an extensive series of weather-exposure tests, which reveal the extent to which the resistance of the materials to corrosion was affected by variable factors in their heat treatment and by the application of various surface protective coatings. The results indicate that the sheet materials are to be regarded as thoroughly reliable, from the standpoint of their permanence in service, provided proper precautions are taken to render them corrosion-resistant.

  4. The development of recycle-friendly automotive aluminum alloys

    NASA Astrophysics Data System (ADS)

    Das, Subodh K.; Green, J. A. S.; Kaufman, J. Gilbert

    2007-11-01

    The continuing growth of aluminum alloy usage in transportation applications, notably passenger automobiles and minivans, and the demonstrated economic benefits of recycling aluminum-rich vehicles increase the need to seriously consider the desirability of designing recycling-friendly alloys. This article focuses on that aspect of the recycling process for passenger vehicles. The goals are to illustrate the opportunities afforded by identifying and taking full advantage of potential metal streams in guiding the development of new alloys that use those streams. In speculating on several possible aluminum recovery practices and systems that might be used in recycling passenger vehicles, likely compositions are identified and preliminary assessments of their usefulness for direct recycling are made. Specific compositions for possible new recycle-friendly alloys are suggested. In addition, recommendations on how the aluminum enterprise, including industry, academia, and government, can work together to achieve the aggressive but important goals described here are discussed.

  5. Cleavage crystallography of liquid metal embrittled aluminum alloys

    NASA Technical Reports Server (NTRS)

    Reynolds, A. P.; Stoner, G. E.

    1991-01-01

    The crystallography of liquid metal-induced transgranular cleavage in six aluminum alloys having a variety of microstructures has been determined via Laue X-ray back reflection. The cleavage crystallography was independent of alloy microstructure, and the cleavage plane was 100-plane oriented in all cases. It was further determined that the cleavage crystallography was not influenced by alloy texture. Examination of the fracture surface indicated that there was not a unique direction of crack propagation. In addition, the existence of 100-plane cleavage on alloy 2024 fracture surfaces was inferred by comparison of secondary cleavage crack intersection geometry on the 2024 surfaces with the geometry of secondary cleavage crack intersections on the test alloys.

  6. Advanced powder metallurgy aluminum alloys via rapid solidification technology

    NASA Technical Reports Server (NTRS)

    Ray, R.

    1984-01-01

    Aluminum alloys containing 10 to 11.5 wt. pct. of iron and 1.5 to 3 wt. pct. of chromium using the technique of rapid solidification powder metallurgy were studied. Alloys were prepared as thin ribbons (.002 inch thick) rapidly solidified at uniform rate of 10(6) C/second by the melt spinning process. The melt spun ribbons were pulverized into powders (-60 to 400 mesh) by a rotating hammer mill. The powders were consolidated by hot extrusion at a high reduction ratio of 50:1. The powder extrusion temperature was varied to determine the range of desirable processing conditions necessary to yield useful properties. Powders and consolidated alloys were characterized by SEM and optical metallography. The consolidated alloys were evaluated for (1) thermal stability, (2) tensile properties in the range, room temperature to 450 F, and (3) notch toughness in the range, room temperature to 450 F.

  7. Enhancement of superplastic formability in a high strength aluminum alloy

    NASA Technical Reports Server (NTRS)

    Agrawal, S. P.; Turk, G. R.; Vastava, R.

    1988-01-01

    A 7475 aluminum alloy was developed for superplastic forming (SPF). By lowering the Fe and Si contents in this alloy significantly below their normal levels and optimizing the thermomechanical processing to produce sheet, over 2000 percent thickness strain to failure was obtained. The microstructure, elevated-temperature uniaxial and biaxial tension, and cavitation behavior of the alloy were determined. In addition, a constitutive model was used to form a generic structural shape from which mechanical test specimens were removed and post-SPF characteristics were evaluated. The constitutive model included both material strain hardening and strain rate hardening effects, and was verified by accurately predicting forming cycles which resulted in successful component forming. Stress-life fatigue, stress rupture, and room and elevated temperature tensile tests were conducted on the formed material.

  8. Environmental Effects on Fatigue Crack Growth in 7075 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Bonakdar, A.; Wang, F.; Williams, J. J.; Chawla, N.

    2012-08-01

    The fatigue behavior of aluminum alloys is greatly influenced by the environmental conditions. In this article, fatigue crack growth rates were measured for 7075-T651 Al alloy under ultrahigh vacuum (UHV, ~10-10 Torr), dry air, and water vapor. Standard compact tension (CT) specimens were tested along the L-T orientation under various load ratios of 0.1, 0.5, and 0.8. Fracture surfaces and crack morphologies were studied using scanning electron microscopy and crack deflection analysis. The crack growth behavior under vacuum was affected by friction and possible rewelding of crack surfaces, causing an asymmetry in the crack growth behavior, from load shedding to constant load. The enhancement of crack growth at higher moisture levels was observed and is discussed in terms of moisture decreasing friction between the crack faces. The effect of crack deflection as a function of R ratio and environment is also presented.

  9. Constant amplitude and post-overload fatigue crack growth behavior in PM aluminum alloy AA 8009

    NASA Technical Reports Server (NTRS)

    Reynolds, A. P.

    1991-01-01

    A recently developed, rapidly solidified, powder metallurgy, dispersion strengthened aluminum alloy, AA 8009, was fatigue tested at room temperature in lab air. Constant amplitude/constant delta kappa and single spike overload conditions were examined. High fatigue crack growth rates and low crack closure levels compared to typical ingot metallurgy aluminum alloys were observed. It was proposed that minimal crack roughness, crack path deflection, and limited slip reversibility, resulting from ultra-fine microstructure, were responsible for the relatively poor da/dN-delta kappa performance of AA 8009 as compared to that of typical IM aluminum alloys.

  10. Constant amplitude and post-overload fatigue crack growth behavior in PM aluminum alloy AA 8009

    NASA Technical Reports Server (NTRS)

    Reynolds, A. P.

    1992-01-01

    A recently developed, rapidly solidified, powder metallurgy, dispersion strengthened aluminum alloy, AA 8009, was fatigue tested at room temperature in lab air. Constant amplitude/constant delta kappa and single spike overload conditions were examined. High fatigue crack growth rates and low crack closure levels compared to typical ingot metallurgy aluminum alloys were observed. It was proposed that minimal crack roughness, crack path delection, and limited slip reversibility, resulting from ultra-fine microstructure, were responsible for the relatively poor da/dN-delta kappa performance of AA 8009 as compared to that of typical IM aluminum alloys.

  11. Small-crack effects in high-strength aluminum alloys

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.; Wu, X. R.; Venneri, S. L.; Li, C. G.

    1994-01-01

    The National Aeronautics and Space Administration and the Chinese Aeronautical Establishment participated in a Fatigue and Fracture Mechanics Cooperative Program. The program objectives were to identify and characterize crack initiation and growth of small cracks (10 microns to 2 mm long) in commonly used US and PRC aluminum alloys, to improve fracture mechanics analyses of surface- and corner-crack configurations, and to develop improved life-prediction methods. Fatigue and small-crack tests were performed on single-edgenotch tension (SENT) specimens and large-crack tests were conducted on center-crack tension specimens for constant-amplitude (stress ratios of -1, 0, and 0.5) and Mini-TWIST spectrum loading. The plastic replica method was used to monitor the initiation and growth of small fatigue cracks at the semicircular notch. Crack growth results from each laboratory on 7075-T6 bare and LC9cs clad aluminum alloys agreed well and showed that fatigue life was mostly crack propagation from a material defect (inclusion particles or void) or from the cladding layer. Finite-element and weight-function methods were used to determine stress intensity factors for surface and corner cracks in the SENT specimens. Equations were then developed and used in a crack growth and crack-closure model to correlate small- and large-crack data and to make life predictions for various load histories. The cooperative program produced useful experimental data and efficient analysis methods for improving life predictions. The results should ultimately improve aircraft structural reliability and safety.

  12. Fretting fatigue of 2XXX series aerospace aluminum alloys

    NASA Astrophysics Data System (ADS)

    Giummarra, Cindie

    Fretting is a wear mechanism that occurs at the contact region between two materials subject to minute cyclic relative motion. Fretting causes the initiation of surface cracks within the first few thousand cycles, which in the presence of a fatigue stress, grow to cause material failure approximately 10 to 100 times earlier than expected under standard fatigue conditions. Examples of fretting fatigue have been seen in joints in aircraft, and the aerospace industry acknowledges the possibility of catastrophic failure from this mechanism. Improvements in a material's resistance to fretting would benefit aluminum alloys in aerospace applications. This research investigated the effect of microstructural properties on the fretting response in 2XXX series aerospace aluminum alloys. Fretting wear and fretting fatigue tests were conducted to determine the influence of slip characteristics, alloy purity, grain orientation and yield strength on fretting crack initiation and growth. Crack length measurements and micrographs of the fretting indicated there was no significant difference in the fretting response of these alloys based on their microstructural characteristics. Results showed that fretting initiated cracks in the first 1--8% of the life while standard fatigue initiation took around 90% of the life. This reduction in initiation resulted in a shorter life under fretting conditions. Additionally, fretting normalized the initiation time in all alloys which eliminated any intrinsic initiation resistance. The alloys with the highest stress-life (S-N) fatigue properties exhibiting a greater reduction in fatigue strength under fretting conditions. The fretting stresses appeared to influence the crack growth to a distance below the surface of approximately 17mum under fretting fatigue conditions, after which some cracks changed direction and propagated under the influence of the fatigue stress. Under fretting wear conditions, the cracks tended to arrest at a depth of 8

  13. Facile formation of superhydrophobic aluminum alloy surface and corrosion-resistant behavior

    NASA Astrophysics Data System (ADS)

    Feng, Libang; Yan, Zhongna; Qiang, Xiaohu; Liu, Yanhua; Wang, Yanping

    2016-03-01

    Superhydrophobic surface with excellent corrosion resistance was prepared on aluminum alloy via boiling water treatment and surface modification with stearic acid. Results suggested that the micro- and nanoscale hierarchical structure along with the hydrophobic chemical composition surface confers the aluminum alloy surface with good superhydrophobicity, and the water contact angle and the water sliding angle can reach 156.6° and 3°, respectively. The corrosion resistance of the superhydrophobic aluminum alloy was first characterized by potentiodynamic polarization, and then the long-term corrosion resistance was investigated by immersing the sample in NaCl solution for 90 days. The surface wettability, morphology, and composition before and after immersion were examined, and results showed that the superhydrophobic aluminum alloy surface possessed good corrosion resistance under the experimental conditions, which is favorable for its practical application as an engineering material in seawater corrosion conditions. Finally, the mechanism of the superhydrophobicity and excellent corrosion resistance is deduced.

  14. Statistical analysis of constituent particles in 7075-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Harlow, D. G.; Wei, R. P.; Wang, M. Z.

    2006-11-01

    Pitting corrosion is a primary degradation mechanism that affects the durability and integrity of aluminum alloy structures especially in aircraft. The heterogeneity of aluminum alloys is directly responsible for pitting corrosion because about 200 constituent particles per mm2 are on polished surfaces. Corrosion pits commence at surface particles and evolve into severe pits by sustained growth through particle clusters. Severe pits are nuclei for subsequent corrosion fatigue cracking. Thus, heterogeneous clusters of constituent particles are critical to the quality of aluminum alloys subjected to deleterious environments. Models for structural reliability including corrosion fundamentally depend on quantitative descriptions of the spatial statistics of the particles and particle clusters, including their location, size, and density. The primary purpose of this effort is to statistically estimate the distribution functions of the key geometrical properties of the constituent particles in 7075-T6 aluminum alloy and their role in pitting corrosion.

  15. Development of Enriched Borated Aluminum Alloy for Basket Material of Cask for Spent Nuclear Fuel

    SciTech Connect

    Katsura Kajihara; Yasuhiro Aruga; Jun Shimojo; Hiroaki Taniuchi; Tsutomu Takeda; Masatosi Sasaki

    2002-07-01

    New enriched borated aluminum alloys manufactured by melting process are developed, which resulted in supplying structural basket materials for spent nuclear fuel packagings. In this process, the borated aluminum alloys were melted in a vacuum induction furnace at elevated temperature than that of ordinary aluminum melting processes. Boron dissolves into the matrix at the temperature of 1273 K or more, and fine aluminum diboride is precipitated and uniformly dispersed upon cooling rapidity. It is confirmed that boron is homogeneously dispersed with the fine particles of approximate 5 in average size in the product. Tensile strength and creep property at elevated temperature in 1 mass-%B 6061-T651 plate and 1 mass-%B 3004 extruded rectangular pipe as structural materials are examined. It is confirmed that the both of borated aluminum alloys have stable strength and creep properties that are similar to those of ordinary aluminum alloys. (authors)

  16. Finite Element Simulation of Plastic Joining Processes of Steel and Aluminum Alloy Sheets

    SciTech Connect

    Mori, K.; Abe, Y.; Kato, T.

    2007-05-17

    Various high tensile strength steel sheets and an aluminum alloy sheet were joined with a self-piercing rivet. It is not easy to weld the aluminum alloy sheet and high tensile strength sheets by means of conventional resistance welding because of very different melting points. To obtain optimum joining conditions, joining defects were categorized into separation of the sheets and an inner fracture. The joining range of ultra high tensile strength steel and aluminum alloy sheets was extended by means of dies optimized by finite element simulation. The joint strength is greatly influenced by not only the strength of the sheets and rivets but also the ratio of the thickness of the lower sheet to the total thickness. In addition, mechanical clinching of high strength steel and aluminum alloy sheets was simulated.

  17. Finite Element Simulation of Plastic Joining Processes of Steel and Aluminum Alloy Sheets

    NASA Astrophysics Data System (ADS)

    Mori, K.; Abe, Y.; Kato, T.

    2007-05-01

    Various high tensile strength steel sheets and an aluminum alloy sheet were joined with a self-piercing rivet. It is not easy to weld the aluminum alloy sheet and high tensile strength sheets by means of conventional resistance welding because of very different melting points. To obtain optimum joining conditions, joining defects were categorized into separation of the sheets and an inner fracture. The joining range of ultra high tensile strength steel and aluminum alloy sheets was extended by means of dies optimized by finite element simulation. The joint strength is greatly influenced by not only the strength of the sheets and rivets but also the ratio of the thickness of the lower sheet to the total thickness. In addition, mechanical clinching of high strength steel and aluminum alloy sheets was simulated.

  18. The mechanism of stress-corrosion cracking in 7075 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Jacobs, A. J.

    1970-01-01

    Various aspects of stress-corrosion cracking in 7075 aluminum alloy are discussed. A model is proposed in which the continuous anodic path along which the metal is preferentially attacked consists of two phases which alternate as anodes.

  19. Biaxial Testing of 2219-T87 Aluminum Alloy Using Cruciform Specimens

    NASA Technical Reports Server (NTRS)

    Dawicke, D. S.; Pollock, W. D.

    1997-01-01

    A cruciform biaxial test specimen was designed and seven biaxial tensile tests were conducted on 2219-T87 aluminum alloy. An elastic-plastic finite element analysis was used to simulate each tests and predict the yield stresses. The elastic-plastic finite analysis accurately simulated the measured load-strain behavior for each test. The yield stresses predicted by the finite element analyses indicated that the yield behavior of the 2219-T87 aluminum alloy agrees with the von Mises yield criterion.

  20. The Effect of Impurities on the Processing of Aluminum Alloys

    SciTech Connect

    Zi-Kui Liu; Shengjun Zhang; Qingyou Han; Vinod Sikka

    2007-04-23

    For this Aluminum Industry of the Future (IOF) project, the effect of impurities on the processing of aluminum alloys was systematically investigated. The work was carried out as a collaborative effort between the Pennsylvania State University and Oak Ridge National Laboratory. Industrial support was provided by ALCOA and ThermoCalc, Inc. The achievements described below were made. A method that combines first-principles calculation and calculation of phase diagrams (CALPHAD) was used to develop the multicomponent database Al-Ca-K-Li-Mg-Na. This method was extensively used in this project for the development of a thermodynamic database. The first-principles approach provided some thermodynamic property data that are not available in the open literature. These calculated results were used in the thermodynamic modeling as experimental data. Some of the thermodynamic property data are difficult, if not impossible, to measure. The method developed and used in this project allows the estimation of these data for thermodynamic database development. The multicomponent database Al-Ca-K-Li-Mg-Na was developed. Elements such as Ca, Li, Na, and K are impurities that strongly affect the formability and corrosion behavior of aluminum alloys. However, these impurity elements are not included in the commercial aluminum alloy database. The process of thermodynamic modeling began from Al-Na, Ca-Li, Li-Na, K-Na, and Li-K sub-binary systems. Then ternary and higher systems were extrapolated because of the lack of experimental information. Databases for five binary alloy systems and two ternary systems were developed. Along with other existing binary and ternary databases, the full database of the multicomponent Al-Ca-K-Li-Mg-Na system was completed in this project. The methodology in integrating with commercial or other aluminum alloy databases can be developed. The mechanism of sodium-induced high-temperature embrittlement (HTE) of Al-Mg is now understood. Using the thermodynamic

  1. Numerical simulation of different pulse width of long pulsed laser on aluminum alloy

    NASA Astrophysics Data System (ADS)

    Li, Mingxin; Jin, Guangyong; Zhang, Wei; Chen, Guibo; Bi, Juan

    2015-03-01

    Established a physical model to simulate the melt ejection induced by long pulsed laser on aluminum alloy and use the finite element method to simulate the whole process. This simulation is based on the interaction between single pulsed laser with different pulse width and different peak energy and aluminum alloy material. By comparing the theoretical simulation data and the actual test data, we discover that: the theoretical simulation curve is well consistent with the actual experimental curve, this two-dimensional model is with high reliability; when the temperature at the center of aluminum alloy surface increases and evaporation happens after the surface temperature at the center of aluminum alloy surface reaches boiling point and later the aluminum alloy material sustains in the status of equilibrium vaporization; the keyhole appears on the surface of the target, an increment of the keyhole, the maximum temperature at the center of aluminum alloy surface gradually moves inwardly. This research may provide the theoretical references to the understanding of the interaction between millisecond pulsed laser and many kinds of materials, as well as be beneficial to the application of the laser materials processing and military field.

  2. Materials Design for Joinable, High Performance Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Glamm, Ryan James

    An aluminum alloy compatible with friction stir welding is designed for automotive and aerospace structural applications. Current weldable automotive aluminum alloys do not possess the necessary strength to meet safety standards and therefore are not able to replace steel in the automotive body. Significant weight savings could be achieved if steel components are replaced with aluminum. Current aerospace alloys are not weldable, requiring machining of large pieces that are then riveted together. If an aerospace alloy could be friction stir welded, smaller pieces could be welded, reducing material waste. Using a systems approach for materials design, property goals are set from performance objectives. From previous research and computational predictions, a structure is designed for a prototype alloy containing dynamic precipitates to readily dissolve and re-precipitate and high stability precipitates to resist dissolution and coarsening in the weld region. It is found that a Ag modified Al-3.9Mg-0.04Cu (at. %) alloy enhanced the rate and magnitude of hardening during ageing, both beneficial effects for dynamic precipitation. In the same alloy, ageing at 350°C results in hardening from Al 3(Sc,Zr) precipitates. Efforts to effectively precipitate both populations simultaneously are unsuccessful. The Al3(Sc,Zr) precipitation hardened prototype is friction stir processed and no weak zones are found in the weld hardness profile. An aerospace alloy design is proposed, utilizing the dual precipitate structure shown in the prototype. The automotive alloy is designed using a basic strength model with parameters determined from the initial prototype alloy analysis. After ageing to different conditions, the alloy is put through a simulated heat affected zone thermal cycle with a computer controlled induction heater. The aged samples lose hardness from the weld cycle but recover hardness from a post weld heat treatment. Atom probe tomography and transmission electron

  3. Anisotropic Effects on Constitutive Model Parameters of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Brar, Nachhatter; Joshi, Vasant

    2011-06-01

    Simulation of low velocity impact on structures or high velocity penetration in armor materials heavily rely on constitutive material models. The model constants are required input to computer codes (LS-DYNA, DYNA3D or SPH) to accurately simulate fragment impact on structural components made of high strength 7075-T651 aluminum alloys. Johnson-Cook model constants determined for Al7075-T651 alloy bar material failed to simulate correctly the penetration into 1' thick Al-7075-T651plates. When simulations go well beyond minor parameter tweaking and experimental results are drastically different it is important to determine constitutive parameters from the actual material used in impact/penetration experiments. To investigate anisotropic effects on the yield/flow stress of this alloy we performed quasi-static and high strain rate tensile tests on specimens fabricated in the longitudinal, transverse, and thickness directions of 1' thick Al7075-T651 plate. Flow stresses at a strain rate of ~1100/s in the longitudinal and transverse direction are similar around 670MPa and decreases to 620 MPa in the thickness direction. These data are lower than the flow stress of 760 MPa measured in Al7075-T651 bar stock.

  4. Tool For Friction Stir Tack Welding of Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Bjorkman, Gerald W.; Dingler, Johnny W.; Loftus, Zachary

    2003-01-01

    A small friction-stir-welding tool has been developed for use in tack welding of aluminum-alloy workpieces. It is necessary to tack-weld the workpieces in order to hold them together during friction stir welding because (1) in operation, a full-size friction-stir-welding tool exerts a large force that tends to separate the workpieces and (2) clamping the workpieces is not sufficient to resist this force. It is possible to tack the pieces together by gas tungsten arc welding, but the process can be awkward and time-consuming and can cause sufficient damage to necessitate rework. Friction stir tack welding does not entail these disadvantages. In addition, friction stir tack welding can be accomplished by use of the same automated equipment (except for the welding tool) used in subsequent full friction stir welding. The tool for friction stir tack welding resembles the tool for full friction stir welding, but has a narrower shoulder and a shorter pin. The shorter pin generates a smaller workpiece-separating force so that clamping suffices to keep the workpieces together. This tool produces a continuous or intermittent partial-penetration tack weld. The tack weld is subsequently consumed by action of the larger tool used in full friction stir welding tool.

  5. and Carbon Fiber Reinforced 2024 Aluminum Alloy Composites

    NASA Astrophysics Data System (ADS)

    Kaczmar, Jacek W.; Naplocha, Krzysztof; Morgiel, Jerzy

    2014-08-01

    The microstructure and mechanical properties of 2024 aluminum alloy composite materials strengthened with Al2O3 Saffil fibers or together with addition of carbon fibers were investigated. The fibers were stabilized in the preform with silica binder strengthened by further heat treatment. The preforms with 80-90% porosity were infiltrated by direct squeeze casting method. The microstructure of the as-cast specimens consisted mainly of α-dendrites with intermetallic compounds precipitated at their boundaries. The homogenization treatment of the composite materials substituted silica binder with a mixture of the Θ phase and silicon precipitates distributed in the remnants of SiO2 amorphous phase. Outside of this area at the binder/matrix interface, fine MgO precipitates were also present. At surface of C fibers, a small amount of fine Al3C4 carbides were formed. During pressure infiltration of preforms containing carbon fibers under oxygen carrying atmosphere, C fibers can burn releasing gasses and causing cracks initiated by thermal stress. The examination of tensile and bending strength showed that reinforcing of aluminum matrix with 10-20% fibers improved investigated properties in the entire temperature range. The largest increase in relation to unreinforced alloy was observed for composite materials examined at the temperature of 300 °C. Substituting Al2O3 Saffil fibers with carbon fibers leads to better wear resistance at dry condition with no relevant effect on strength properties.

  6. High-Temperature Workability of Thixocast A356 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Singh, Shailesh Kumar; Chattopadhyay, K.; Dutta, Pradip

    2015-07-01

    The present work highlights the role of globular microstructure on the workability of A356 aluminum alloy at elevated temperature. The hot deformation behavior was studied by isothermal hot compression tests in the temperature range 573 K to 773 K (300 °C to 500 °C) and strain rate range of 0.001 to 10 s-1. The flow stress data obtained from the tests were used to estimate the strain rate sensitivity and strain rate hardening. Flow stress analysis of the alloy shows that the effect of temperature on strain hardening is more significant at lower strain levels and strain rate sensitivity is independent of strain. The results also reveal that the flowability of conventionally cast alloy increases after changing the dendritic microstructure into a globular structure through semisolid processing route. Thixocast alloy exhibits lower yield strength and higher elongation at elevated temperature in comparisons to conventionally cast values. This property has an important implication toward thixo-forming at an elevated temperature.

  7. Superplastic Behavior of Copper-Modified 5083 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Verma, Ravi; Kim, Sooho

    2007-04-01

    An AA5083 aluminum alloy was modified with two different levels of Cu additions, cast by direct-chill method, and thermo-mechanically processed to sheet gauge. Copper additions reduced sheet grain size, decreased tensile flow stress and significantly increased tensile elongation under most elevated temperature test conditions. The high-Cu (0.8 wt.%) alloy had the finest grain size 5.3 μm, a peak strain-rate sensitivity of 0.6 at a strain-rate of 1 × 10-2 s-1, and tensile elongation values between 259 and 584% over the temperature range, 400-525 °C, and the strain rate range, 5 × 10-4 to 1 × 10-2 s-1, investigated. In biaxial pan forming tests, only the Cu-containing alloys successfully formed pans at the higher strain rate 10-2 s-1. The high-Cu alloy showed the least die-entry thinning. Comparison of ambient temperature mechanical properties in O-temper state showed the high-Cu alloy to have significantly higher yield strength, ultimate strength, and ductility compared to the base 5083 alloy.

  8. Pigment-derived inhibitors for aluminum alloy 2024-T3

    SciTech Connect

    Cook, R.L. Jr.; Taylor, S.R.

    2000-03-01

    Inhibitor characteristics of 27 compounds considered as possible replacements for chromate pigments in aerospace paint were investigated. These compounds were tested and screened in solution and not as actual paint additives. In initial testing, aluminum alloy (AA) 2024-T3 (UNS A92024) samples were exposed to 0.6 M sodium chloride (NaCl, pH adjusted to 7, T = 23 C) with 3.4 mM of the candidate compound dissolved in solution. Corrosion inhibition characteristics were assessed via electrochemical impedance spectroscopy (EIS) performed over 10 days, and the statistical analysis of pit depths was analyzed at the conclusion of each exposure. Promising candidates then were exposed to more extreme environments to simulate possible service-life conditions. These environments included unbuffered 0.6 M NaCl initially adjusted to pH 3, T = 23 C and pH 10, T = 23 C. Several candidate inhibitors appeared promising: barium metaborate, cerium chloride, cerium oxalate, lanthanum chloride, and sodium metavanadate. Under the conditions of these tests, sodium metavanadate consistently displayed the best performance. EIS data indicated the corrosion performance of sodium metavanadata was within an order of magnitude of sodium chromate (Na{sub 2}CrO{sub 4}), while pit depth values for metavanadate were comparable to those observed for Na{sub 2}CrO{sub 4}. Rankings of inhibitor performance as determined by EIS was supported by the extreme value analysis of pit depth.

  9. Numerical simulation of high speed incremental forming of aluminum alloy

    NASA Astrophysics Data System (ADS)

    Giuseppina, Ambrogio; Teresa, Citrea; Luigino, Filice; Francesco, Gagliardi

    2013-12-01

    In this study, an innovative process is analyzed with the aim to satisfy the industrial requirements, such as process flexibility, differentiation and customizing of products, cost reduction, minimization of execution time, sustainable production, etc. The attention is focused on incremental forming process, nowadays used in different fields such as: rapid prototyping, medical sector, architectural industry, aerospace and marine, in the production of molds and dies. Incremental forming consists in deforming only a small region of the workspace through a punch driven by a NC machine. SPIF is the considered variant of the process, in which the punch gives local deformation without dies and molds; consequently, the final product geometry can be changed by the control of an actuator without requiring a set of different tools. The drawback of this process is its slowness. The aim of this study is to assess the IF feasibility at high speeds. An experimental campaign will be performed by a CNC lathe with high speed to test process feasibility and the influence on materials formability mainly on aluminum alloys. The first results show how the material presents the same performance than in conventional speed IF and, in some cases, better material behavior due to the temperature field. An accurate numerical simulation has been performed to investigate the material behavior during the high speed process substantially confirming experimental evidence.

  10. Luminescence properties of oxide coatings on aluminum alloys

    NASA Astrophysics Data System (ADS)

    Pershukevich, P. P.; Shabrov, D. V.; Osipov, V. P.; Schreiber, J.; Lapina, V. A.

    2011-09-01

    This is a study of the luminescence properties of coatings formed on aluminum alloys by anodizing in electrolytic solutions based on oxalic, sulfuric, and tartaric-sulfonic acids. At least two emission centers, with band maxima in the ranges of 390-410 and 470-510 nm, can be reliably identified in the photoluminescence spectra. The first type of center is characterized by single-band photoluminescence excitation spectra and the second, by two-band spectra. An analysis of the two-band photoluminescence excitation (PLE) spectra in the range of 470-510 nm shows that the position of the narrow short-wavelength PLE spectrum near 272 nm is independent of the type of acid used in the anodization process. The position and shape of the other PLE spectral bands depend both on the type of acid used and on the processing of the alloy or alumina surfaces. It is assumed that defect-free alumina centers are responsible for the 272 nm PLE band, while the other photoluminescence bands are caused primarily by different divacancies of oxygen ( {F_2^+} , F 2, and {F_2^{+2}} centers) whose origin is governed by the type of electrolyte.

  11. Strengthening of Aluminum Alloy 2219 by Thermo-mechanical Treatment

    NASA Astrophysics Data System (ADS)

    Li, Xifeng; Lei, Kun; Song, Peng; Liu, Xinqin; Zhang, Fei; Li, Jianfei; Chen, Jun

    2015-10-01

    Strengthening of aluminum alloy 2219 by thermo-mechanical treatment has been compared with artificial aging. Three simple deformation modes including pre-stretching, compression, and rolling have been used in thermo-mechanical treatment. The tensile strength, elongation, fracture feature, and precipitated phase have been investigated. The results show that the strengthening effect of thermo-mechanical treatment is better than the one of artificial aging. Especially, the yield strength significantly increases with a small decrease of elongation. When the specimen is pre-stretched to 8.0%, the yield strength reaches 385.0 MPa and increases by 22.2% in comparison to the one obtained in aging condition. The maximum tensile strength of 472.4 MPa is achieved with 4.0% thickness reduction by compression. The fracture morphology reveals locally ductile and brittle failure mechanism, while the coarse second-phase particles distribute on the fracture surface. The intermediate phases θ″ or θ' orthogonally precipitate in the matrix after thermo-mechanical treatment. As compared to artificial aging, the cold plastic deformation increases distribution homogeneity and the volume fraction of θ'' or θ' precipitates. These result in a better strengthening effect.

  12. Cooling Rate Determination in Additively Manufactured Aluminum Alloy 2219

    NASA Astrophysics Data System (ADS)

    Brice, Craig A.; Dennis, Noah

    2015-05-01

    Metallic additive manufacturing processes generally utilize a conduction mode, welding-type approach to create beads of deposited material that can be arranged into a three-dimensional structure. As with welding, the cooling rates in the molten pool are relatively rapid compared to traditional casting techniques. Determination of the cooling rate in the molten pool is critical for predicting the solidified microstructure and resultant properties. In this experiment, wire-fed electron beam additive manufacturing was used to melt aluminum alloy 2219 under different thermal boundary conditions. The dendrite arm spacing was measured in the remelted material, and this information was used to estimate cooling rates in the molten pool based on established empirical relationships. The results showed that the thermal boundary conditions have a significant effect on the resulting cooling rate in the molten pool. When thermal conduction is limited due to a small thermal sink, the dendrite arm spacing varies between 15 and 35 µm. When thermal conduction is active, the dendrite arm spacing varies between 6 and 12 µm. This range of dendrite arm spacing implies cooling rates ranging from 5 to 350 K/s. Cooling rates can vary greatly as thermal conditions change during deposition. A cooling rate at the higher end of the range could lead to significant deviation from microstructural equilibrium during solidification.

  13. A calorimetric study of precipitation in aluminum alloy 2219

    NASA Astrophysics Data System (ADS)

    Papazian, John M.

    1981-02-01

    Precipitate microstructures in aluminum alloy 2219 were characterized using transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The DSC signatures of individual precipitate phases were established by comparing the DSC and TEM results from samples that had been aged such that only one precipitate phase was present. These signatures were then used to analyze the commercial tempers. It was found that DSC could readily distinguish between the T3, T4, T6, T8 and O tempers but could not distinguish amongst T81, T851 and T87. Small amounts of plastic deformation between solution treatment and aging had a significant effect on the thermograms. Aging experiments at 130 and 190 °C showed that the aging sequence and DSC response of this alloy were similar to those of pure Al-Cu when the increased copper content is taken into account. Further aging experiments at temperatures between room temperature and 130 °C showed pronounced changes of the GP zone dissolution peak as a function of aging conditions. These changes were found to be related to the effect of GP zone size on the metastable phase boundary and on the GP zone dissolution kinetics.

  14. Radiation Damages in Aluminum Alloy SAV-1 under Neutron Irradiation

    NASA Astrophysics Data System (ADS)

    Salikhbaev, Umar; Akhmedzhanov, Farkhad; Alikulov, Sherali; Baytelesov, Sapar; Boltabaev, Azizbek

    2016-05-01

    The aim of this work was to study the effect of neutron irradiation on the kinetics of radiation damages in the SAV-1 alloy, which belongs to the group of aluminum alloys of the ternary system Al-Mg-Si. For fast-neutron irradiation by different doses up to fluence 1019 cm-2 the SAV-1 samples were placed in one of the vertical channels of the research WWR type reactor (Tashkent). The temperature dependence of the electrical resistance of the alloy samples was investigated in the range 290 - 490 K by the four-compensation method with an error about 0.1%. The experimental results were shown that at all the temperatures the dependence of the SAV-1 alloy resistivity on neutron fluence was nonlinear. With increasing neutron fluence the deviation from linearity and the growth rate of resistivity with temperature becomes more appreciable. The observed dependences are explained by means of martensitic transformations and the radiation damages in the studied alloy under neutron irradiation. The mechanisms of radiation modification of the SAV-1 alloy structure are discussed.

  15. Thermal Decoating of Aerospace Aluminum Alloys for Aircraft Recycling

    NASA Astrophysics Data System (ADS)

    Muñiz Lerma, Jose Alberto; Jung, In-Ho; Brochu, Mathieu

    2016-03-01

    Recycling of aircraft aluminum alloys can be complex due to the presence of their corrosion protection coating that includes inorganic compounds containing Cr(VI). In this study, the characterization and thermal degradation behavior of the coating on aluminum substrates coming from an aircraft destined for recycling are presented. Elements such as Sr, Cr, Si, Ba, Ti, S, C, and O were found in three different layers by EDS elemental mapping corresponding to SrCrO4, Rutile-TiO2, SiO2, and BaSO4 with an overall particle size D 50 = 1.96 µm. The thermal degradation profile analyzed by TGA showed four different stages. The temperature of complete degradation at the fourth stage occurred at 753.15 K (480 °C) at lower heating rates. At higher heating rates and holding an isotherm at the same temperature, the residence time to fully decompose the aircraft coating has been estimated as 4.0 ± 0.2 minutes. The activation energy calculated by the Flynn-Wall-Ozawa and the modified Coats-Redfern methods for multiple fraction of decomposition showed a non-constant behavior indicating the complexity of the reaction. Finally, the concentration of Cr(VI) released to the environment during thermal decoating was obtained by UV-Vis spectroscopy. It was found that 2.6 ± 0.1 µg of Cr(VI)/mm2 of aluminum substrate could be released unless adequate particle controls are used.

  16. Anisotropic effects on constitutive model parameters of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Brar, Nachhatter S.; Joshi, Vasant S.

    2012-03-01

    Simulation of low velocity impact on structures or high velocity penetration in armor materials heavily rely on constitutive material models. Model constants are determined from tension, compression or torsion stress-strain at low and high strain rates at different temperatures. These model constants are required input to computer codes (LS-DYNA, DYNA3D or SPH) to accurately simulate fragment impact on structural components made of high strength 7075-T651 aluminum alloy. Johnson- Cook model constants determined for Al7075-T651 alloy bar material failed to simulate correctly the penetration into 1' thick Al-7075-T651plates. When simulation go well beyond minor parameter tweaking and experimental results show drastically different behavior it becomes important to determine constitutive parameters from the actual material used in impact/penetration experiments. To investigate anisotropic effects on the yield/flow stress of this alloy quasi-static and high strain rate tensile tests were performed on specimens fabricated in the longitudinal "L", transverse "T", and thickness "TH" directions of 1' thick Al7075 Plate. While flow stress at a strain rate of ~1/s as well as ~1100/s in the thickness and transverse directions are lower than the longitudinal direction. The flow stress in the bar was comparable to flow stress in the longitudinal direction of the plate. Fracture strain data from notched tensile specimens fabricated in the L, T, and Thickness directions of 1' thick plate are used to derive fracture constants.

  17. Thermal Decoating of Aerospace Aluminum Alloys for Aircraft Recycling

    NASA Astrophysics Data System (ADS)

    Muñiz Lerma, Jose Alberto; Jung, In-Ho; Brochu, Mathieu

    2016-06-01

    Recycling of aircraft aluminum alloys can be complex due to the presence of their corrosion protection coating that includes inorganic compounds containing Cr(VI). In this study, the characterization and thermal degradation behavior of the coating on aluminum substrates coming from an aircraft destined for recycling are presented. Elements such as Sr, Cr, Si, Ba, Ti, S, C, and O were found in three different layers by EDS elemental mapping corresponding to SrCrO4, Rutile-TiO2, SiO2, and BaSO4 with an overall particle size D 50 = 1.96 µm. The thermal degradation profile analyzed by TGA showed four different stages. The temperature of complete degradation at the fourth stage occurred at 753.15 K (480 °C) at lower heating rates. At higher heating rates and holding an isotherm at the same temperature, the residence time to fully decompose the aircraft coating has been estimated as 4.0 ± 0.2 minutes. The activation energy calculated by the Flynn-Wall-Ozawa and the modified Coats-Redfern methods for multiple fraction of decomposition showed a non-constant behavior indicating the complexity of the reaction. Finally, the concentration of Cr(VI) released to the environment during thermal decoating was obtained by UV-Vis spectroscopy. It was found that 2.6 ± 0.1 µg of Cr(VI)/mm2 of aluminum substrate could be released unless adequate particle controls are used.

  18. Influence of Shot Peening on Failure of an Aluminum Alloy Exposed to Aggressive Aqueous Environments

    NASA Astrophysics Data System (ADS)

    Lv, Shengli; Cu, You; Zhang, Wei; Tong, Xiaoyan; Srivatsan, T. S.; Gao, Xiaosheng

    2013-06-01

    Pre-corrosion damage tests were performed on the high strength aluminum alloy (Al-Zn-Mg-Cu) that was subject to shot peening surface treatment. The tests were performed for different time levels and compared one-on-one with the performance and characteristics of the non-shot-peened alloy. The residual stress induced by the shot peening surface treatment for two different intensity levels was measured using the method of incremental drilling of holes. Based on an observation of morphology of corrosion experienced by the aluminum alloy the depth of corrosion was measured using a laser displacement sensor. The surface of the aluminum alloy that was shot peened revealed an overall better resistance to pitting while concurrently revealing evidence of partial degradation. The depth of degradation is related to the residual stress that is induced in the aluminum alloy sample by the shot peening treatment. The key mechanisms that control damage during corrosion of the shot-peened aluminum alloy can be divided into the distinct stages of (a) initial occurrence of uniform corrosion followed by (b) the generation of degradation, and (c) culminating in the initiation of pitting once the depth of degradation reaches a certain level.

  19. A Fatigue Model for Discontinuous Particulate-Reinforced Aluminum Alloy Composite: Influence of Microstructure

    NASA Astrophysics Data System (ADS)

    McCullough, R. R.; Jordon, J. B.; Brammer, A. T.; Manigandan, K.; Srivatsan, T. S.; Allison, P. G.; Rushing, T. W.

    2014-01-01

    In this paper, the use of a microstructure-sensitive fatigue model is put forth for the analysis of discontinuously reinforced aluminum alloy metal matrix composite. The fatigue model was used for a ceramic particle-reinforced aluminum alloy deformed under conditions of fully reversed strain control. Experimental results revealed the aluminum alloy to be strongly influenced by volume fraction of the particulate reinforcement phase under conditions of strain-controlled fatigue. The model safely characterizes the evolution of fatigue damage in this aluminum alloy composite into the distinct stages of crack initiation and crack growth culminating in failure. The model is able to capture the specific influence of particle volume fraction, particle size, and nearest neighbor distance in quantifying fatigue life. The model yields good results for correlation of the predicted results with the experimental test results on the fatigue behavior of the chosen aluminum alloy for two different percentages of the ceramic particle reinforcement. Further, the model illustrates that both particle size and volume fraction are key factors that govern fatigue lifetime. This conclusion is well supported by fractographic observations of the cyclically deformed and failed specimens.

  20. Lightweight materials for automotive applications/topic 2: Wear resistant aluminum alloy

    SciTech Connect

    Viswanathan, S.

    1997-01-31

    The replacement of cast iron by aluminum alloys in automotive engine blocks and heads represents a significant weight reduction in automobiles. The primary hurdle to the widespread use of aluminum alloy engine blocks in the North American automobile industry was high cost. The lack of wear resistance in most aluminum alloys added to manufacturing cost, since expensive procedures such as the incorporation of cast iron liners or special coatings were needed to achieve the required wear properties. The project targeted the development of a wear resistant aluminum alloy, as well as tools and the knowledge-base required to design the casting process, to allow it to be cast economically into engine blocks without the use of a cast iron liner or special coating, thereby providing benefits to both the material and manufacturing aspects of the process. The project combined the alloy development, wear and microstructural characterization, and casting modeling capabilities of the laboratory with the partners extensive alloy and casting process development and manufacturing experience to develop a suitable wear resistant aluminum alloy and casting process.

  1. Determination of dynamic shear strength of 2024 aluminum alloy under shock compression

    NASA Astrophysics Data System (ADS)

    Zhang, H. S.; Yan, M.; Wang, H. Y.; Shen, L. T.; Dai, L. H.

    2016-04-01

    A series of plate impact shock-reshock and shock-release experiments were conducted by using an one-stage light gas gun to determine the critical shear strength of the 2024 aluminum alloy under shock compression levels ranging from 0.66 to 3.05 GPa in the present study. In the experiments, a dual flyer plate assembly, i.e., the 2024 aluminum alloy flyer backed either by a brass plate or a PMMA plate, was utilized to produce reshock or release wave. The stress profiles of uniaxial plane strain wave propagation in the 2024 aluminum alloy sample under different pre-compressed states were measured by the embedded stress gauges. The stress-strain data at corresponding states were then calculated by a Lagrangian analysis method named as path line method. The critical shear strengths at different stress levels were finally obtained by self-consistent method. The results show that, at the low shock compression level (0.66 to 3.05 GPa), the critical shear strength of the 2024 aluminum alloy cannot be ignored and increases with the increasing longitudinal stress, which may be attributed to rate-dependence and/or pressure dependent yield behavior of the 2024 aluminum alloy.

  2. Precipitation during infiltration of A201 aluminum alloy into Al-Fe-V-Si preform

    SciTech Connect

    Yang, C.C.; Chen, Y.C.; Chang, E.

    1996-04-01

    The newly developed Al-Fe-V-Si aluminum alloy, produced by melt spinning into ribbons, comminution of ribbon to particles, and then consolidation of particles by extrusion and forging, is being considered for high temperature applications due to the material`s characteristics of high elevated temperature strength, low density, good toughness and thermal stability. In order to extend the near-net shaping capability of the material, the authors have proposed a new process that Al-Fe-V-Si aluminum alloy particles can be consolidated by casting, in which the liquid aluminum alloy was infiltrated around the Al-Fe-V-Si particles to form a FVS1212/A201 composite material. Preliminary study of the Al-Fe-V-Si particle reinforced A201 aluminum alloy composite demonstrated that the compression strength at 300 C can be twice as high as A201 aluminum alloy. This work constitutes a continuation of the previous efforts to understand the microstructural evolution sequences, particularly the precipitation events during infiltration of the liquid aluminum into Al-Fe-V-Si preform.

  3. A New Creep Constitutive Model for 7075 Aluminum Alloy Under Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Lin, Y. C.; Jiang, Yu-Qiang; Zhou, Hua-Min; Liu, Guan

    2014-12-01

    Exposure of aluminum alloy to an elastic loading, during "creep-aging forming" or other manufacturing processes at relatively high temperature, may lead to the lasting creep deformation. The creep behaviors of 7075 aluminum alloy are investigated by uniaxial tensile creep experiments over wide ranges of temperature and external stress. The results show that the creep behaviors of the studied aluminum alloy strongly depend on the creep temperature, external stress, and creep time. With the increase of creep temperature and external stress, the creep strain increases quickly. In order to overcome the shortcomings of the Bailey-Norton law and θ projection method, a new constitutive model is proposed to describe the variations of creep strain with time for the studied aluminum alloy. In the proposed model, the dependences of creep strain on the creep temperature, external stress, and creep time are well taken into account. A good agreement between the predicted and measured creep strains shows that the established creep constitutive model can give an accurate description of the creep behaviors of 7075 aluminum alloy. Meanwhile, the obtained stress exponent indicates that the creep process is controlled by the dislocation glide, which is verified by the microstructural observations.

  4. Subsurface Aluminum Nitride Formation in Iron-Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Bott, June H.

    Transformation-induced plasticity (TRIP) steels containing higher amounts of aluminum than conventional steels are ideal for structural automotive parts due to their mechanical properties. However, the aluminum tends to react with any processing environment at high temperatures and therefore presents significant challenges during manufacturing. One such challenge occurs during secondary cooling, reheating, and hot-rolling and is caused by a reaction with nitrogen-rich atmospheres wherein subsurface aluminum nitride forms in addition to internal and external oxides. The nitrides are detrimental to mechanical properties and cause surface cracks. It is important to understand how these nitrides and oxides form and their consequences for the quality of steel products. This study looks at model iron-aluminum (up to 8 wt.% aluminum) alloys and uses confocal laser scanning microscopy, x-ray diffraction, scanning electron microscopy with energy dispersive x-ray spectrometry, and transmission electron microscopy to study the effect of various conditions on the growth and development of these precipitates in a subsurface oxygen-depleted region. By using model alloys and controlling the experimental atmosphere, this study is able to understand some of the more fundamental materials science behind aluminum nitride formation in aluminum-rich iron alloys and the relationship between internal nitride and oxide precipitation and external oxide scale morphology and composition. The iron-aluminum alloys were heated in N2 atmospheres containing oxygen impurities. It was found that nitrides formed when bulk aluminum content was below 8 wt.% when oxygen was sufficiently depleted due to the internal oxidation. In the samples containing 1 wt.% aluminum, the depth of the internal oxide and nitride zones were in agreement with a diffusion-based model. Increasing aluminum content to 3 and 5 wt% had the effects of modifying the surface-oxide scale composition and increasing its continuity

  5. Simulation of 7050 Wrought Aluminum Alloy Wheel Die Forging and its Defects Analysis based on DEFORM

    SciTech Connect

    Huang Shiquan; Yi Youping; Zhang Yuxun

    2010-06-15

    Defects such as folding, intercrystalline cracking and flow lines outcrop are very likely to occur in the forging of aluminum alloy. Moreover, it is difficult to achieve the optimal set of process parameters just by trial and error within an industrial environment. In producing 7050 wrought aluminum alloy wheel, a rigid-plastic finite element method (FEM) analysis has been performed to optimize die forging process. Processing parameters were analyzed, focusing on the effects of punch speed, friction factor and temperature. Meanwhile, mechanism as well as the evolution with respect to the defects of the wrought wheel was studied in details. From an analysis of the results, isothermal die forging was proposed for producing 7050 aluminum alloy wheel with good mechanical properties. Finally, verification experiment was carried out on hydropress.

  6. A study on friction stir welding of 12mm thick aluminum alloy plates

    NASA Astrophysics Data System (ADS)

    Kumar, Deepati Anil; Biswas, Pankaj; Tikader, Sujoy; Mahapatra, M. M.; Mandal, N. R.

    2013-12-01

    Most of the investigations regarding friction stir welding (FSW) of aluminum alloy plates have been limited to about 5 to 6 mm thick plates. In prior work conducted the various aspects concerning the process parameters and the FSW tool geometry were studied utilizing friction stir welding of 12 mm thick commercial grade aluminum alloy. Two different simple-to-manufacture tool geometries were used. The effect of varying welding parameters and dwell time of FSW tool on mechanical properties and weld quality was examined. It was observed that in order to achieve a defect free welding on such thick aluminum alloy plates, tool having trapezoidal pin geometry was suitable. Adequate tensile strength and ductility can be achieved utilizing a combination of high tool rotational speed of about 2000 r/min and low speed of welding around 28 mm/min. At very low and high dwell time the ductility of welded joints are reduced significantly.

  7. Commercialization of NASA's High Strength Cast Aluminum Alloy for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2003-01-01

    In this paper, the commercialization of a new high strength cast aluminum alloy, invented by NASA-Marshall Space Flight Center, for high temperature applications will be presented. Originally developed to meet U.S. automotive legislation requiring low- exhaust emission, the novel NASA aluminum alloy offers dramatic improvement in tensile and fatigue strengths at elevated temperatures (450 F-750 F), which can lead to reducing part weight and cost as well as improving performance for automotive engine applications. It is an ideal low cost material for cast components such as pistons, cylinder heads, cylinder liners, connecting rods, turbo chargers, impellers, actuators, brake calipers and rotors. NASA alloy also offers greater wear resistance, dimensional stability, and lower thermal expansion compared to conventional aluminum alloys, and the new alloy can be produced economically from sand, permanent mold and investment casting. Since 2001, this technology was licensed to several companies for automotive and marine internal combustion engines applications.

  8. Improvements of welding characteristics of aluminum alloys with YAG laser and TIG arc hybrid system

    NASA Astrophysics Data System (ADS)

    Fujinaga, Shigeki; Ohashi, Ryoji; Katayama, Seiji; Matsunawa, Akira

    2003-03-01

    In high power YAG laser welding of steels, a rectangularly modulated beam with high peak power is usually used to get deep penetration. On the other hand, many spatters and solidification cracks are generated when some aluminum alloys are welded with a rectangularly modulated beam because of its high heat conductivity, high reflectivity, low surface tension, large contraction, wide solidification temperature range, etc. Therefore, a properly modulated beam or a continuous beam is usually used in aluminum alloy welding, although the penetration depth is shallow. In this research, sinusoidal wave or rectangularly modulated wave of YAG laser combined with TIG arc was tried to improve the weldability of A6061 aluminum alloy. As a result, when TIG arc was superimposed behind the YAG laser beam, deeply penetrated weld beads with good surface appearances were produced without spatter losses and cracks.

  9. The effect of pre-existing corrosion on the fatigue cracking behavior of aluminum alloys

    SciTech Connect

    Hagerdorn, E.L.; Koch, G.H.

    1996-10-01

    In order to assess the effect of preexisting corrosion on the fatigue crack behavior of aluminum alloys 2024-T3 and 7074-T6 crack initiation and growth data were obtained using fracture mechanics specimens. These specimens incorporated mechanically thinned areas and areas that had been preexposed to environments which produced various degrees of pitting or exfoliation corrosion. The data obtained from these laboratory experiments indicate that specific corrosive was most pronounced in the fatigue cracking behavior of aluminum alloys. The effect of preexisting corrosion was most pronounced in the fatigue crack initiation stage. Based on the results of this study, it was concluded that the effect of preexisting corrosion on the fatigue cracking behavior of both aluminum alloys 2024-T3 and 7075-T6 is a combination of stress concentrations as a result of material loss, and altered material properties, possible as a result of hydrogen entry into the lattice.

  10. Macrosegregation in aluminum alloy ingot cast by the semicontinuous direct chill method

    NASA Technical Reports Server (NTRS)

    Yu, H.; Granger, D. A.

    1984-01-01

    A theoretical model of the semicontinuous DC casting method is developed to predict the positive segregation observed at the subsurface and the negative segregation commonly found at the center of large commercial-size aluminum alloy ingot. Qualitative analysis of commercial-size aluminum alloy semicontinuous cast direct chill (DC) ingot is carried out. In the analysis, both positive segregation in the ingot subsurface and negative segregation at the center of the ingot are examined. Ingot subsurface macrosegregation is investigated by considering steady state casting of a circular cross-section binary alloy ingot. Nonequilibrium solidification is assumed with no solid diffusion, constant equilibrium partition ratio, and constant solid density.

  11. Low-cycle fatigue resistance of AD1 aluminum and AMg5 aluminum alloy

    SciTech Connect

    Kholodilo, A.A.; Balyuk, L.M.; Modestova, R.V.

    1985-02-01

    This paper reports on investigations carried out by the Severodonetsk branch of the Ukranian Scientific-Research Institute of Chemical Engineering into the low-cycle fatigue resistance of aluminum AD1 and AMg/sup 5/ aluminum alloy. The cylindrical specimens were tested in an UME-1oTM machine with recording of the cyclic deformation diagram. It is concluded that the Landger equation can be used to construct the calculation curves of low-cycle fatigue of the aluminum alloys; the quality of the welded joints plays the controlling role in the resistance of the vessels and plant to low-cycle fracture.

  12. Fabrication of super-hydrophobic surfaces on aluminum alloy substrates by RF-sputtered polytetrafluoroethylene coatings

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Liu, Xiao Wei; Zhang, Hai Feng; Zhou, Zhi Ping

    2014-03-01

    In this work, we present a method of fabricating super-hydrophobic surface on aluminum alloy substrate. The etching of aluminum surfaces has been performed using Beck's dislocation etchant for different time to create micrometer-sized irregular steps. An optimised etching time of 50 s is found to be essential before polytetrafluoroethylene (PTFE) coating, to obtain a highest water contact angle of 165±2° with a lowest contact angle hysteresis as low as 5±2°. The presence of patterned microstructure as revealed by scanning electron microscopy (SEM) together with the low surface energy ultrathin RF-sputtered PTFE films renders the aluminum alloy surfaces highly super-hydrophobic.

  13. Boron-doped back-surface fields using an aluminum-alloy process

    SciTech Connect

    Gee, J.M.; Bode, M.D.; Silva, B.L.

    1997-10-01

    Boron-doped back-surface fields (BSF`s) have potentially superior performance compared to aluminum-doped BSF`s due to the higher solid solubility of boron compared to aluminum. However, conventional boron diffusions require a long, high temperature step that is both costly and incompatible with many photovoltaic-grade crystalline-silicon materials. We examined a process that uses a relatively low-temperature aluminum-alloy process to obtain a boron-doped BSF by doping the aluminum with boron. In agreement with theoretical expectations, we found that thicker aluminum layers and higher boron doping levels improved the performance of aluminum-alloyed BSF`s.

  14. Fabrication of super-hydrophobic surfaces on aluminum alloy substrates by RF-sputtered polytetrafluoroethylene coatings

    SciTech Connect

    Wang, Yang; Liu, Xiao Wei; Zhang, Hai Feng Zhou, Zhi Ping

    2014-03-15

    In this work, we present a method of fabricating super-hydrophobic surface on aluminum alloy substrate. The etching of aluminum surfaces has been performed using Beck's dislocation etchant for different time to create micrometer-sized irregular steps. An optimised etching time of 50 s is found to be essential before polytetrafluoroethylene (PTFE) coating, to obtain a highest water contact angle of 165±2° with a lowest contact angle hysteresis as low as 5±2°. The presence of patterned microstructure as revealed by scanning electron microscopy (SEM) together with the low surface energy ultrathin RF-sputtered PTFE films renders the aluminum alloy surfaces highly super-hydrophobic.

  15. Power ultrasound irradiation during the alkaline etching process of the 2024 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Moutarlier, V.; Viennet, R.; Rolet, J.; Gigandet, M. P.; Hihn, J. Y.

    2015-11-01

    Prior to any surface treatment on an aluminum alloy, a surface preparation is necessary. This commonly consists in performing an alkaline etching followed by acid deoxidizing. In this work, the use of power ultrasound irradiation during the etching step on the 2024 aluminum alloy was studied. The etching rate was estimated by weight loss, and the alkaline film formed during the etching step was characterized by glow discharge optical emission spectrometry (GDOES) and scanning electron microscope (SEM). The benefit of power ultrasound during the etching step was confirmed by pitting potential measurement in NaCl solution after a post-treatment (anodizing).

  16. The Column Strength of Two Extruded Aluminum-Alloy H-Sections

    NASA Technical Reports Server (NTRS)

    Osgood, William R; Holt, Marshall

    1939-01-01

    Extruded aluminum-alloy members of various cross sections are used in aircraft as compression members either singly or as stiffeners for aluminum-alloy sheet. In order to design such members, it is necessary to know their column strength or, in the case of stiffeners, the value of the double modulus, which is best obtained for practical purposes from column tests. Column tests made on two extruded h-sections are described, and column formulas and formulas for the ratio of the double modulus to Young's modulus, based on the tests, are given.

  17. All-aluminum-alloy UHV chamber for molecular beam epitaxy, 1

    NASA Astrophysics Data System (ADS)

    Suemitsu, M.; Miyamoto, N.

    1984-03-01

    The first all aluminum alloy (ex. JIS.6263-t6,2219-t87 etc) MBE chamber is constructed and described. After exposure to atmosphere, the chamber is drown to 10(-9) torr in 24 hours, and reaches an ultrahigh vacuum of 1.6x10(-10) torr by a 115 C, 24 bakeout process. The light weight and low cost as well as the short pump-down time and the law outgassing rate of the all aluminum alloy vacuum system seems to have a considerable applicative potentiality for equipment used in semiconductor ultrahigh vacuum processes.

  18. Trivalent chromium pre-treatment for corrosion protection of aluminum alloys -- an electrochemical evaluation

    SciTech Connect

    Agarwala, V.S.; Beckert, D.W.; Fabiszewski, A.S.; Pearlstein, F.

    1994-12-31

    A corrosion resistant chemical conversion coating on aluminum alloys was developed using a trivalent chromium bath. Electrochemical impedance spectroscopy and dc-polarization measurements were made to determine the nature of the surface films formed. The results showed a 10 to 100 fold increase in the polarization resistance of the surface films compared to the untreated aluminum alloy. These electrochemical results compared well with the corrosion behavior in salt spray tests. The trivalent chromium-treated surfaces showed no corrosion for up to 200 hours in 5% salt spray. A post-treatment with an oxidizer even further improved its resistance which almost doubled its corrosion protection.

  19. Applications of high-temperature powder metal aluminum alloys to small gas turbines

    NASA Technical Reports Server (NTRS)

    Millan, P. P., Jr.

    1982-01-01

    A program aimed at the development of advanced powder-metallurgy (PM) aluminum alloys for high-temperature applications up to 650 F using the concepts of rapid solidification and mechanical alloying is discussed. In particular, application of rapidly solidified PM aluminum alloys to centrifugal compressor impellers, currently used in auxiliary power units for both military and commercial aircraft and potentially for advanced automotive gas turbine engines, is examined. It is shown that substitution of high-temperature aluminum for titanium alloy impellers operating in the 360-650 F range provides significant savings in material and machining costs and results in reduced component weight, and consequently, reduced rotating group inertia requirements.

  20. Interfacial characterization of joint between mild steel and aluminum alloy welded by resistance spot welding

    SciTech Connect

    Qiu Ranfeng; Shi Hongxin; Zhang Keke; Tu Yimin; Iwamoto, Chihiro; Satonaka, Shinobu

    2010-07-15

    The interfacial characteristics of resistance spot welded steel-aluminum alloy joint have been investigated using electron microscopy. The results reveal that reaction product FeAl{sub 3} is generated in the peripheral region of the weld while a reaction layer consisting of Fe{sub 2}Al{sub 5} adjacent to steel and FeAl{sub 3} adjacent to aluminum alloy forms in the central region of the weld, and that the morphology and thickness of the reaction layer vary with the position at the welding interface.

  1. Evaluation of Sc-Bearing Aluminum Alloy C557 for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Domack, Marcia S.; Dicus, Dennis L.

    2002-01-01

    The performance of the Al-Mg-Sc alloy C557 was evaluated to assess its potential for a broad range of aerospace applications, including airframe and launch vehicle structures. Of specific interest were mechanical properties at anticipated service temperatures and thermal stability of the alloy. Performance was compared with conventional airframe aluminum alloys and with other emerging aluminum alloys developed for specific service environments. Mechanical properties and metallurgical structure were evaluated for commercially rolled sheet in the as-received H116 condition and after thermal exposures at 107 C. Metallurgical analyses were performed to de.ne grain morphology and texture, strengthening precipitates, and to assess the effect of thermal exposure.

  2. Plasma Source Ion Implantation of Aluminum and Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Walter, Kevin Carl

    Three plasma source ion implantation (PSII) schemes applied to three aluminum systems have been studied. Pure aluminum, and aluminum alloys 7075 (Al-Cu-Mg-Zn) and A390 (Al-17Si-Cu-Fe) were (1) argon ion sputter-cleaned and nitrogen-implanted, (2) nitrogen-implanted without sputter -cleaning, and (3) argon-implanted. Nitrogen implantation was performed with the goal of modifying the surface properties by transformation of the surface to aluminum-nitride. Argon implantation was performed with the goal of modifying the surface properties by inducing radiation damage. All implantation schemes were accomplished using a glow discharge mode of the PSII process. Implanted surfaces were investigated using Auger depth profiling and Transmission Electron Microscopy. The profiles indicated a stoichiometric layer, ~ 0.15 μm thick, of AlN on the nitrogen-implanted samples. Electron microscopy confirmed the complete conversion of the aluminum surface to AlN. Knoop microhardness tests showed an increase in surface hardness, especially at low loads. The improvements were independent of prior sputter-cleaning and were approximately equal for the studied aluminum systems. Pin-on-disk wear tests were conducted using a ruby stylus and isopropanol lubrication. Argon implantation decreased the wear resistance of pure aluminum and 7075. Nitrogen implantation improved the wear rates by a factor of ~10 for pure aluminum and 7075. These improvements were independent of prior sputter-cleaning. The coefficient of friction was not significantly influenced by the implantation schemes. Due to a coarse microstructure, tribological tests of ion-implanted A390 were inconclusive. Corrosion studies performed in a 3.5 wt% NaCl solution (seawater) indicated nitrogen implantation gave pure aluminum improved corrosion resistance. The improvement is due to the complete conversion of the aluminum surface to AlN. Because of pre-existing precipitates, the corrosion properties of 7075 and A390 were not

  3. Diffusion Bonding and Characterization of a Dispersion Strengthened Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Cooke, Kavian Omar

    Aluminum metal matrix composites (Al-MMC's) containing silicon carbide or alumina particle reinforcements are used extensively in automotive and aircraft industries. The addition of a reinforcing phase has led to significant improvements in the mechanical properties of these alloys. However, despite substantial improvements in the properties, the lack of a reliable joining method has restricted their full potential. The differences in physical and metallurgical properties between the ceramic phase and the Al-MMC, prevents the successful application of the fusion welding processes, conventionally used for joining monolithic aluminum alloys. Therefore, alternative techniques that prevent microstructural changes in the base metal need to be developed. In this study, the transient liquid phase diffusion bonding and eutectic bonding of a particle reinforced Al 6061-MMC was investigated to identify a method that could control particle segregation within the joint and increase the final joint strength. The results showed that TLP bonding using Ni-foil was possible at 600°C for 10 minutes using a pressure of 0.01 MPa. However, characterization of the bond interface showed a wide particle segregated zone due to the "pushing effect" of the solid/liquid interface during isothermal solidification stage of bonding. The presence of this particle segregated zone was shown to cause low joint strengths. In order to overcome these problems, TLP bonding was performed using electrodeposited coatings of Ni and Ni-Al 2O3 as a way of controlling the volume of eutectic liquid formed at the joint. Theoretical and experimental work showed that the use of thin coatings was successful in reducing the width of the segregated zone formed at the joint and this had the effect of increasing joint shear strength values. Furthermore, lower bonding temperature could also be used as a method of reducing particle segregation and therefore, a Cu-Sn interlayer was used to form a eutectic bond. The

  4. Elevated temperature crack growth in advanced powder metallurgy aluminum alloys

    NASA Technical Reports Server (NTRS)

    Porr, William C., Jr.; Gangloff, Richard P.

    1990-01-01

    Rapidly solidified Al-Fe-V-Si powder metallurgy alloy FVS0812 is among the most promising of the elevated temperature aluminum alloys developed in recent years. The ultra fine grain size and high volume fraction of thermally stable dispersoids enable the alloy to maintain tensile properties at elevated temperatures. In contrast, this alloy displays complex and potentially deleterious damage tolerant and time dependent fracture behavior that varies with temperature. J-Integral fracture mechanics were used to determine fracture toughness (K sub IC) and crack growth resistance (tearing modulus, T) of extruded FVS0812 as a function of temperature. The alloy exhibits high fracture properties at room temperature when tested in the LT orientation, due to extensive delamination of prior ribbon particle boundaries perpendicular to the crack front. Delamination results in a loss of through thickness constraint along the crack front, raising the critical stress intensity necessary for precrack initiation. The fracture toughness and tensile ductility of this alloy decrease with increasing temperature, with minima observed at 200 C. This behavior results from minima in the intrinsic toughness of the material, due to dynamic strain aging, and in the extent of prior particle boundary delaminations. At 200 C FVS0812 fails at K levels that are insufficient to cause through thickness delamination. As temperature increases beyond the minimum, strain aging is reduced and delamination returns. For the TL orientation, K (sub IC) decreased and T increased slightly with increasing temperature from 25 to 316 C. Fracture in the TL orientation is governed by prior particle boundary toughness; increased strain localization at these boundaries may result in lower toughness with increasing temperature. Preliminary results demonstrate a complex effect of loading rate on K (sub IC) and T at 175 C, and indicate that the combined effects of time dependent deformation, environment, and strain aging

  5. Effect of tool pin features on process response variables during friction stir welding of dissimilar aluminum alloys

    DOE PAGESBeta

    Rabby, Reza; Tang, Wei; Reynolds, A. P.

    2015-05-13

    In this article, the effect of pin features and orientation/placement of the materials on advancing side were investigated for friction stir welding (FSW) of dissimilar aluminum alloys AA2050 and AA6061. Pins for FSW were produced with a 2.12 mm pitch thread having three flats/flutes. Three sets of rotational speed/welding speed were used to perform a series of welds in a butt joint arrangement. The results show that, joint quality, process response variables and welding temperature are highly affected by pin features and material orientation in FSW. Defect free joints with effective material transportation in the weld nugget zone were obtainedmore » when welding was performed with AA2050 on the advancing side. The tool also encounters less in-plane reaction force for welding with 2050 on the advancing side. Pin with thread+3 flats produces quality welds at low rotational and travel speed regardless of the location of alloys on advancing or retreating side.« less

  6. Effect of tool pin features on process response variables during friction stir welding of dissimilar aluminum alloys

    SciTech Connect

    Rabby, Reza; Tang, Wei; Reynolds, A. P.

    2015-05-13

    In this article, the effect of pin features and orientation/placement of the materials on advancing side were investigated for friction stir welding (FSW) of dissimilar aluminum alloys AA2050 and AA6061. Pins for FSW were produced with a 2.12 mm pitch thread having three flats/flutes. Three sets of rotational speed/welding speed were used to perform a series of welds in a butt joint arrangement. The results show that, joint quality, process response variables and welding temperature are highly affected by pin features and material orientation in FSW. Defect free joints with effective material transportation in the weld nugget zone were obtained when welding was performed with AA2050 on the advancing side. The tool also encounters less in-plane reaction force for welding with 2050 on the advancing side. Pin with thread+3 flats produces quality welds at low rotational and travel speed regardless of the location of alloys on advancing or retreating side.

  7. Effect of tool pin features on process response variables during friction stir welding of dissimilar aluminum alloys

    SciTech Connect

    Rabby, Reza; Tang, Wei; Reynolds, A. P.

    2015-07-01

    In this article, the effect of pin features and orientation/placement of the materials on advancing side were investigated for friction stir welding (FSW) of dissimilar aluminum alloys AA2050 and AA6061. Pins for FSW were produced with a 2.12 mm pitch thread having three flats/flutes. Three sets of rotational speed/welding speed were used to perform a series of welds in a butt joint arrangement. The results show that, joint quality, process response variables and welding temperature are highly affected by pin features and material orientation in FSW. Defect free joints with effective material transportation in the weld nugget zone were obtained when welding was performed with AA2050 on the advancing side. The tool also encounters less in-plane reaction force for welding with 2050 on the advancing side. Pin with thread+3 flats produces quality welds at low rotational and travel speed regardless of the location of alloys on advancing or retreating side.

  8. A mathematical model to predict the strength of aluminum alloys subjected to precipitation hardening

    SciTech Connect

    Qureshi, F.S.; Sheikh, A.K.; Rashid, M.

    1999-06-01

    A number of alloys, notably most of the aluminum alloys, can be heat treated by aging. This aging due to time-dependent precipitation hardening increases the strength and hardness as well as modifying other mechanical properties. Precipitation hardening has been a popular strengthening mechanism for many decades; therefore, extensive information is available in literature about the precipitation-hardening response of various series of aluminum alloys. The age-hardening response of these alloys is usually represented in graphical form as plotted between property changes and aging time for different temperatures. In designing a suitable precipitation-hardening strategy, one can refer to these graphs. However, for automatic control of aging furnaces, as well as for decision making regarding optimal selection of aging conditions (time/temperature combination), it is desirable to express these relationships in a formal mathematical structure. A mathematical model is developed in this article for widely used heat treatable aluminum alloys used in the extrusion industry. This model is a condensed representation of all {sigma} = f(T,t) curves in different series of aluminum alloys, and the parameters of this model characterize the various compositions of the alloys in the series.

  9. The corrosion protection of several aluminum alloys by chromic acid and sulfuric acid anodizing

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1994-01-01

    The corrosion protection afforded 7075-T6, 7075-T3, 6061-T6, and 2024-T3 aluminum alloys by chromic acid and sulfuric acid anodizing was examined using electrochemical techniques. From these studies, it is concluded that sulfuric acid anodizing provides superior corrosion protection compared to chromic acid anodizing.

  10. Experimental Observations of 5A02 Aluminum Alloy in Electromagnetically Assisted Tube Hydroforming

    NASA Astrophysics Data System (ADS)

    Chu, Guannan; Liu, Wenjian

    2013-05-01

    To establish the efficiency of electromagnetically assisted tube hydroforming, a typical experimental test for hydroforming, i.e., hydrobulging, was carried out on a 5A02 tube blank by using a combined quasi-static axial feeding and pulsed electromagnetic hydrobulging method. Data on the formability of an aluminum alloy 5A02 tube employing this combined loading method is compared with data for traditional quasi-static tests. The results show that the formability of aluminum alloy undergoing a quasi-static-dynamic process is dramatically increased beyond that exhibited in quasi-static or fully dynamic tests. The ultimate expansion ratio of an aluminum alloy tube undergoing a pulsed electromagnetic hydrobulging process is greatly increased beyond that exhibited in quasi-static hydrobulging tests. Both the expansion ratio and the effective strain exhibited in electromagnetically assisted tube hydroforming tests are about four and two times of that in quasi-static and fully dynamic hydrobulging tests, respectively. The forming limits of aluminum samples with both low and high prestrain levels are almost similar in the electromagnetically assisted tube hydroforming process, which makes it possible to stretch the aluminum alloy to a higher quasi-static prestrain level without weakening its total quasi-static-dynamic formability.

  11. Mechanical Properties of Friction Stir Welded Aluminum Alloys 5083 and 5383

    NASA Astrophysics Data System (ADS)

    Paik, Jeoom Kee

    2009-09-01

    The use of high-strength aluminum alloys is increasing in shipbuilding industry, particularly for the design and construction of war ships, littoral surface craft and combat ships, and fast passenger ships. While various welding methods are used today to fabricate aluminum ship structures, namely gas metallic arc welding (GMAW), laser welding and friction stir welding (FSW), FSW technology has been recognized to have many advantages for the construction of aluminum structures, as it is a low-cost welding process. In the present study, mechanical properties of friction stir welded aluminum alloys are examined experimentally. Tensile testing is undertaken on dog-bone type test specimen for aluminum alloys 5083 and 5383. The test specimen includes friction stir welded material between identical alloys and also dissimilar alloys, as well as unwelded (base) alloys. Mechanical properties of fusion welded aluminum alloys are also tested and compared with those of friction stir welded alloys. The insights developed from the present study are documented together with details of the test database. Part of the present study was obtained from the Ship Structure Committee project SR-1454 (Paik, 2009), jointly funded by its member agencies

  12. Quench sensitivity of hot extruded 6061-T6 and 6069-T6 aluminum alloys

    SciTech Connect

    Bergsma, S C; Kassner, M E; Li, X; Rosen, R S

    2000-08-08

    The purpose of this study is to investigate the quench sensitivity of mechanical properties of hot extruded 6061 and 6069 aluminum alloys. The relationship between mechanical properties and quench delzty time at various temperatures between 200-500 C was determined. It was concluded that the 6069-T6 was somewhat more quench sensitive than 6061, which may be consistent with the composition difference.

  13. Effect of aging on mechanical properties of aluminum-alloy rivets

    NASA Technical Reports Server (NTRS)

    Roop, Frederick C

    1941-01-01

    Curves and tabular data present the results of strength tests made during and after 2 1/2 years of aging on rivets and rivet wire of 3/16-inch nominal diameter. The specimens were of aluminum alloy: 24s, 17s, and a17s of the duralumin type and 53s of the magnesium-silicide type.

  14. Microbiologically induced corrosion of aluminum alloys in fuel-oil/aqueous system.

    PubMed

    Yang, S S; Lin, J Y; Lin, Y T

    1998-09-01

    To investigate the microbiologically induced corrosion of aluminum alloys in fuel-oil/aqueous system, aluminum alloys A356, AA 5052, AA 5083 and AA 6061 were chosen as the test alloys and Cladosporium and several fuel-oil contaminated microbes isolated in Taiwan were used as test organisms. Aluminum alloy AA 5083 in fuel-oil/aqueous system was the most susceptible material for microbial corrosion, then followed by aluminum alloys AA 5052 and A356, and AA 6061 was more resistant to microbial aggression. Mixed culture had high capability of corrosion, then followed by Penicillium sp. AM-F5, Fusarium sp. AM-F1, Pseudomonas aeruginosa AM-B5, Ps. fluorescens AM-B9, C. resinae ATCC 22712, Penicillium sp. AM-F2, Candida sp. AM-Y1 and Ps. aeruginosa AM-B11. From energy dispersive spectrometer analysis, aluminum and magnesium contents decreased in the corrosion area, while chlorine and sulfur contents increased. The major organic acid produced in fuel-oil/aqueous system was acetic acid, and the total organic acids content had a positive correlation with the degree of microbial corrosion. PMID:10496152

  15. Fabrication of superhydrophobic surface with improved corrosion inhibition on 6061 aluminum alloy substrate

    NASA Astrophysics Data System (ADS)

    Li, Xuewu; Zhang, Qiaoxin; Guo, Zheng; Shi, Tian; Yu, Jingui; Tang, Mingkai; Huang, Xingjiu

    2015-07-01

    This work has developed a simple and low-cost method to render 6061 aluminum alloy surface superhydrophobicity and excellent corrosion inhibition. The superhydrophobic aluminum alloy surface has been fabricated by hydrochloric acid etching, potassium permanganate passivation and fluoroalkyl-silane modification. Meanwhile, the effect of the etching and passivation time on the wettability and corrosion inhibition of the fabricated surface has also been investigated. Results show that with the etching time of 6 min and passivation time of 180 min the fabricated micro/nano-scale terrace-like hierarchical structures accompanying with the nanoscale coral-like network bulge structures after being modified can result in superhydrophobicity with a water contact angle (CA) of 155.7°. Moreover, an extremely weak adhesive force to droplets as well as an outstanding self-cleaning behavior of the superhydrophobic surface has also been proved. Finally, corrosion inhibition in seawater of the as-prepared aluminum alloy surface is characterized by potentiodynamic polarization curves and electrochemical impedance spectroscopy. Evidently, the fabricated superhydrophobic surface attained an improved corrosion inhibition efficiency of 83.37% compared with the traditional two-step processing consisting of etching and modification, which will extend the further applications of aluminum alloy especially in marine engineering fields.

  16. A Constitutive Model of 6111-T4 Aluminum Alloy Sheet Based on the Warm Tensile Test

    NASA Astrophysics Data System (ADS)

    Hua, Lin; Meng, Fanzhi; Song, Yanli; Liu, Jianing; Qin, Xunpeng; Suo, Lianbing

    2014-03-01

    As main light-weight material, aluminum alloy sheets have been widely applied to produce auto body panels. In order to predict the formability and springback of aluminum alloy sheets, a precise constitutive model is a necessity. In this article, a series of warm tensile tests were conducted on Gleeble-1500D thermal mechanical simulator for 6111-T4 aluminum alloy sheets. The corresponding strain rate ranged from 0.015 to 1.5 s-1, and the temperature ranged from 25 to 350 °C. The relationship between the temperature, the strain rate, and the flow stress were discussed. A constitutive model based on the updated Fields-Backofen equation was established to describe the flow behavior of 6111-T4 aluminum alloy during the warm tensile tests. Subsequently, the average absolute relative error (AARE) was introduced to verify the predictability of the constitutive model. The value of AARE at the uniform plastic deformation stage was calculated to be 1.677%, which demonstrates that the predicted flow stress values were in accordance with the experimental ones. The constitutive model was validated by the fact that the simulated results of the warm tensile tests coincided with the experimental ones.

  17. The effect of hydrogen embrittlement on the localized plastic deformation of aluminum alloy

    SciTech Connect

    Bochkareva, Anna Lunev, Aleksey; Barannikova, Svetlana; Gorbatenko, Vadim; Shlyakhova, Galina; Zuev, Lev

    2015-10-27

    The effect of hydrogen embrittlement on the localized plastic deformation of aluminum alloy D1 was investigated. The studies were performed for the test samples of aluminum alloy subjected to electrolytic hydrogenation. It is found that the mechanical properties and localized plastic deformation parameters of aluminum alloy are affected adversely by hydrogen embrittlement. The hydrogenated counterpart of alloy has a lower degree of ductility relative to the original alloy; however, the plastic flow behavior of material remains virtually unaffected. Using scanning electron and atomic force microscopy methods, the changes in the fracture surface were investigated. The deformation diagrams were examined for the deformed samples of aluminum alloy. These are found to show all the plastic flow stages: the linear, parabolic and pre-failure stages would occur for the respective values of the exponent n from the Ludwik-Holomon equation. Using digital speckle image technique, the local strain patterns were being registered for the original alloy D1 and the counterpart subjected to electrolytic hydrogenation for 100 h.

  18. Materials data handbooks prepared for aluminum alloys 2014, 2219, and 5456, and stainless steel alloy 301

    NASA Technical Reports Server (NTRS)

    1967-01-01

    Materials data handbooks summarize all presently known properties of commercially available structural aluminum alloys 2014, 2219, and 5456 and structural stainless steel alloy 301. The information includes physical and mechanical property data and design data presented in tables, illustrations, and text.

  19. Thermal stress-relief treatments for 2219 aluminum alloy are evaluated

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Evaluation of three thermal stress relief treatments for 2219 aluminum alloy in terms of their effect on residual stress, mechanical properties, and stress corrosion resistance. The treatments are post aging and stress relieving fullscale and subscale parts formed in the aged T81 condition, and aging subscale parts formed in the unaged T31 condition.

  20. Industrial capability to chem-mill aluminum alloy 2219 in T-37 and T-87

    NASA Technical Reports Server (NTRS)

    Milewski, C., Jr.; Chen, K. C. S.

    1979-01-01

    Procedures and chemical baths were developed for chem-milling aluminum alloy 2219. Using a series of sample etchings, it was found that good etching results could be obtained by using 'white plastic for porcelain repair (toluol, xylol, and petroleum distillates)' on top of cellosolve acetate as resist coatings and ferric chloride as on etchant.

  1. The effect of hydrogen embrittlement on the localized plastic deformation of aluminum alloy

    NASA Astrophysics Data System (ADS)

    Bochkareva, Anna; Lunev, Aleksey; Barannikova, Svetlana; Gorbatenko, Vadim; Shlyakhova, Galina; Zuev, Lev

    2015-10-01

    The effect of hydrogen embrittlement on the localized plastic deformation of aluminum alloy D1 was investigated. The studies were performed for the test samples of aluminum alloy subjected to electrolytic hydrogenation. It is found that the mechanical properties and localized plastic deformation parameters of aluminum alloy are affected adversely by hydrogen embrittlement. The hydrogenated counterpart of alloy has a lower degree of ductility relative to the original alloy; however, the plastic flow behavior of material remains virtually unaffected. Using scanning electron and atomic force microscopy methods, the changes in the fracture surface were investigated. The deformation diagrams were examined for the deformed samples of aluminum alloy. These are found to show all the plastic flow stages: the linear, parabolic and pre-failure stages would occur for the respective values of the exponent n from the Ludwik-Holomon equation. Using digital speckle image technique, the local strain patterns were being registered for the original alloy D1 and the counterpart subjected to electrolytic hydrogenation for 100 h.

  2. Precipitate evolution in friction stir welding of 2219-T6 aluminum alloys

    SciTech Connect

    Chen, Y.C.; Feng, J.C.; Liu, H.J.

    2009-06-15

    Precipitate evolution in friction stir welding of 2219-T6 aluminum alloys was characterized by transmission electron microscopy. In the weld nugget zone and the thermo-mechanically affected zone some metastable precipitates overaged to equilibrium phase while others solutionized into the aluminum solid solution. In the heat-affected zone the precipitates coarsened.

  3. ENVIRONMENTALLY COMPLIANT CORROSION-ACTIVATED INHIBITOR SYSTEM FOR ALUMINUM ALLOYS - PHASE I

    EPA Science Inventory

    The federal government is estimated to spend $1 billion on painting/repainting aircraft annually. Aircraft have surfaces composed of aluminum alloys that are highly susceptible to corrosion and must be protected with corrosion-preventative treatments that typically conta...

  4. Effect of aging on mechanical properties of aluminum-alloy rivets

    NASA Technical Reports Server (NTRS)

    Roop, Frederick C

    1941-01-01

    Curves and tabular data present the results of strength tests made during and after 2 1/2 years of aging on rivets and rivet wire of 3/16-inch nominal diameter. The specimens were of aluminum alloy: 24S, 17S, and A17S of the duralumin type and 53S of the magnesium-silicide type.

  5. Measurements of degree of sensitization (DoS) in aluminum alloys using EMAT ultrasound.

    PubMed

    Li, Fang; Xiang, Dan; Qin, Yexian; Pond, Robert B; Slusarski, Kyle

    2011-07-01

    Sensitization in 5XXX aluminum alloys is an insidious problem characterized by the gradual formation and growth of beta phase (Mg(2)Al(3)) at grain boundaries, which increases the susceptibility of alloys to intergranular corrosion (IGC) and intergranular stress-corrosion cracking (IGSCC). The degree of sensitization (DoS) is currently quantified by the ASTM G67 Nitric Acid Mass Loss Test, which is destructive and time consuming. A fast, reliable, and non-destructive method for rapid detection and the assessment of the condition of DoS in AA5XXX aluminum alloys in the field is highly desirable. In this paper, we describe a non-destructive method for measurements of DoS in aluminum alloys with an electromagnetic acoustic transducer (EMAT). AA5083 aluminum alloy samples were sensitized at 100°C with processing times varying from 7days to 30days. The DoS of sensitized samples was first quantified with the ASTM 67 test in the laboratory. Both ultrasonic velocity and attenuation in sensitized specimens were then measured using EMAT and the results were correlated with the DoS data. We found that the longitudinal wave velocity was almost a constant, independent of the sensitization, which suggests that the longitudinal wave can be used to determine the sample thickness. The shear wave velocity and especially the shear wave attenuation are sensitive to DoS. Relationships between DoS and the shear velocity, as well as the shear attenuation have been established. Finally, we performed the data mining to evaluate and improve the accuracy in the measurements of DoS in aluminum alloys with EMAT. PMID:21232777

  6. Fabrication of the superhydrophobic surface on aluminum alloy by anodizing and polymeric coating

    NASA Astrophysics Data System (ADS)

    Liu, Wenyong; Luo, Yuting; Sun, Linyu; Wu, Ruomei; Jiang, Haiyun; Liu, Yuejun

    2013-01-01

    We reported the preparation of the superhydrophobic surface on aluminum alloy via anodizing and polymeric coating. Both the different anodizing processes and different polymeric coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. The results showed that a good superhydrophobic surface was facilely fabricated by polypropylene (PP) coating after anodizing. The optimum conditions for anodizing were determined by orthogonal experiments. When the concentration of oxalic acid was 10 g/L, the concentration of NaCl was 1.25 g/L, anodization time was 40 min, and anodization current was 0.4 A, the best superhydrophobic surface on aluminum alloy with the contact angle (CA) of 162° and the sliding angle of 2° was obtained. On the other hand, the different polymeric coatings, such as polystyrene (PS), polypropylene (PP) and polypropylene grafting maleic anhydride (PP-g-MAH) were used to coat the aluminum alloy surface after anodizing. The results showed that the superhydrophobicity was most excellent by coating PP, while the duration of the hydrophobic surface was poor. By modifying the surface with the silane coupling agent before PP coating, the duration of the superhydrophobic surface was improved. The morphologies of the superhydrophobic surface were further confirmed by optical microscope (OM) and scanning electron microscope (SEM). Combined with the material of PP with the low surface free energy, the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface.

  7. Aluminum alloys for satellite boxes : engineering guidelines for obtaining adequate strength while minimizing residual stresses and machining distortion.

    SciTech Connect

    Younger, Mandy S.; Eckelmeyer, Kenneth Hall

    2007-11-01

    This report provides strategies for minimizing machining distortion in future designs of aluminum alloy satellite boxes, based in part on key findings from this investigation. The report outlines types of aluminum alloys and how they are heat treated, how residual stresses develop during heat treatment of age hardening alloys, ways residual stresses can be minimized, and the design of machining approaches to minimize distortion in parts that contain residual stresses. Specific recommendations are made regarding alloy selection, heat treatment, stress relieving, and machining procedures for boxes requiring various strength levels with emphasis on 6061 and 7075 aluminum alloys.

  8. Continuous Severe Plastic Deformation Processing of Aluminum Alloys

    SciTech Connect

    Raghavan Srinivasan; Prabir K. Chaudhury; Balakrishna Cherukuri; Qingyou Han; David Swenson; Percy Gros

    2006-06-30

    by SPD techniques. This combination of properties makes UFG metals produced by SPD very attractive as machining, forging or extrusion stock, both from the point of view of formability as well as energy and cost saving. However, prior to this work there had been no attempt to transfer these potential benefits observed in the laboratory scale to industrial shop floor. The primary reason for this was that the laboratory scale studies had been conducted to develop a scientific understanding of the processes that result in grain refinement during SPD. Samples that had been prepared in the laboratory scale were typically only about 10-mm diameter and 50-mm long (about 0.5-inch diameter and 2-inches long). The thrust of this project was three-fold: (i) to show that the ECAE/P process can be scaled up to produce long samples, i.e., a continuous severe plastic deformation (CSPD) process, (ii) show the process can be scaled up to produce large cross section samples that could be used as forging stock, and (iii) use the large cross-section samples to produce industrial size forgings and demonstrate the potential energy and cost savings that can be realized if SPD processed stock is adopted by the forging industry. Aluminum alloy AA-6061 was chosen to demonstrate the feasibility of the approach used. The CSPD process developed using the principles of chamber-less extrusion and drawing, and was demonstrated using rolling and wire drawing equipment that was available at Oak Ridge National Laboratory. In a parallel effort, ECAE/P dies were developed for producing 100-mm square cross section SPD billets for subsequent forging. This work was carried out at Intercontinental Manufacturing Co. (IMCO), Garland TX. Forging studies conducted with the ECAE/P billets showed that many of the potential benefits of using UFG material can be realized. In particular, the material yield can be increased, and the amount of material that is lost as scrap can be reduced by as much as 50%. Forging

  9. Finite Element Analysis and Die Design of Non-specific Engineering Structure of Aluminum Alloy during Extrusion

    SciTech Connect

    Chen, D.-C.; Lu, Y.-Y.

    2010-06-15

    Aluminum extension applies to industrial structure, light load, framework rolls and conveyer system platform. Many factors must be controlled in processing the non-specific engineering structure (hollow shape) of the aluminum alloy during extrusion, to obtain the required plastic strain and desired tolerance values. The major factors include the forming angle of the die and temperature of billet and various materials. This paper employs rigid-plastic finite element (FE) DEFORM 3D software to investigate the plastic deformation behavior of an aluminum alloy (A6061, A5052, A3003) workpiece during extrusion for the engineering structure of the aluminum alloy. This work analyzes effective strain, effective stress, damage and die radius load distribution of the billet under various conditions. The analytical results confirm the suitability of the current finite element software for the non-specific engineering structure of aluminum alloy extrusion.

  10. A study on the surface shape and roughness of aluminum alloy for heat exchanger using ball end milling

    NASA Astrophysics Data System (ADS)

    Lee, E.; Kim, Y.; jeong, H.; Chung, H.

    2015-09-01

    Aluminum alloy is a material with a high strength-weight ratio and excellent thermal conductivity. It neither readily corrodes nor quickly weakens at low temperatures, but can be easily recycled. Because of these features, aluminum heat exchangers are widely used in aluminum alloy. In addition, the aluminum alloy used in other areas is expected to gradually increase. As a result, researchers have been continuously studying the cutting patterns of aluminium alloy. However, such studies are fewer than those on the cutting patterns of ordinary steel. Moreover, the research on ball end milling with aluminium alloys has not received much attention. Therefore, in this study, an attempt was made to find the optimal cutting pattern among the seven cutting patterns for the machining of the commonly used aluminum alloy using ball end milling for a heat exchanger. The optimal pattern was found by comparing the different shapes and surface roughness values produced by the seven patterns.

  11. [Comparison of texture distribution of cold rolled DC and CC AA 5052 aluminum alloy at different positions through thickness direction by XRD].

    PubMed

    Chen, Ming-biao; Ma, Min; Yang, Qing-xiang; Wang, Shan; Liu, Wen-chang; Zhao, Ying-mei

    2013-09-01

    To provide gist of DC AA 5052 and CC AA 5052 aluminum alloy to industry production and application, the texture variation of cold rolled sheets through thickness direction was studied by X-ray diffraction method, and the difference in texture at surface, quarter and center layer was analyzed. The hot plates of direct chill cast (DC) AA 5052 and continuous cast (CC) AA 5052 aluminum alloy were annealed at 454 degrees C for 4 hours and then cold rolled to different reductions. The strength and volume fraction of the fiber in CC AA 5052 aluminum alloy is larger than in DC AA 5052 aluminum alloy after same rolling reduction The volume fraction of the recrystallization texture cube in the CC AA 5052 aluminum alloy is less than in the DC AA 5052 aluminum alloy, which result in that CC AA 5052 aluminum alloy needs less cold rolling reduction than DC AA 5052 aluminum alloy for generating the texture with same intensity and volume fraction at surface layer, quarter layer and center layer. The manufacturability and performance of CC AA 5052 aluminum alloy is superior to DC AA 5052 aluminum alloy for use in stamping. PMID:24369675

  12. Preparations and properties of anti-corrosion additives of water-soluble metal working fluids for aluminum alloy materials.

    PubMed

    Watanabe, Shoji

    2008-01-01

    This short review describes various types of anti-corrosion additives of water-soluble metal working fluids for aluminum alloy materials. It is concerned with synthetic additives classified according to their functional groups; silicone compounds, carboxylic acids and dibasic acids, esters, Diels-Alder adducts, various polymers, nitrogen compounds, phosphoric esters, phosphonic acids, and others. Testing methods for water-soluble metal working fluids for aluminum alloy materials are described for a practical application in a laboratory. PMID:18075217

  13. Warm Forming of Aluminum Alloys using a Coupled Thermo-Mechanical Anisotropic Material Model

    SciTech Connect

    Abedrabbo, Nader; Pourboghrat, Farhang; Carsley, John E.

    2005-08-05

    Temperature-dependant anisotropic material models for two types of automotive aluminum alloys (5754-O and 5182-O) were developed and implemented in LS-Dyna as a user material subroutine (UMAT) for coupled thermo-mechanical finite element analysis (FEA) of warm forming of aluminum alloys. The anisotropy coefficients of the Barlat YLD2000 plane stress yield function for both materials were calculated for the range of temperatures 25 deg. C-260 deg. C. Curve fitting was used to calculate the anisotropy coefficients of YLD2000 and the flow stress as a function of temperature. This temperature-dependent material model was successfully applied to the coupled thermo-mechanical analysis of stretching of aluminum sheets and results were compared with experiments.

  14. Warm Forming of Aluminum Alloys using a Coupled Thermo-Mechanical Anisotropic Material Model

    NASA Astrophysics Data System (ADS)

    Abedrabbo, Nader; Pourboghrat, Farhang; Carsley, John E.

    2005-08-01

    Temperature-dependant anisotropic material models for two types of automotive aluminum alloys (5754-O and 5182-O) were developed and implemented in LS-Dyna as a user material subroutine (UMAT) for coupled thermo-mechanical finite element analysis (FEA) of warm forming of aluminum alloys. The anisotropy coefficients of the Barlat YLD2000 plane stress yield function for both materials were calculated for the range of temperatures 25°C-260°C. Curve fitting was used to calculate the anisotropy coefficients of YLD2000 and the flow stress as a function of temperature. This temperature-dependent material model was successfully applied to the coupled thermo-mechanical analysis of stretching of aluminum sheets and results were compared with experiments.

  15. Evaluation of Aluminum Alloy 2050-T84 Microstructure and Mechanical Properties at Ambient and Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Hafley, Robert A.; Domack, Marcia S.; Hales, Stephen J.; Shenoy, Ravi N.

    2011-01-01

    Aluminum alloy 2050 is being considered for the fabrication of cryogenic propellant tanks to reduce the mass of future heavy-lift launch vehicles. The alloy is available in section thicknesses greater than that of the incumbent aluminum alloy, 2195, which will enable designs with greater structural efficiency. While ambient temperature design allowable properties are available for alloy 2050, cryogenic properties are not available. To determine its suitability for use in cryogenic propellant tanks, tensile, compression and fracture tests were conducted on 4 inch thick 2050-T84 plate at ambient temperature and at -320degF. Various metallurgical analyses were also performed in order to provide an understanding of the compositional homogeneity and microstructure of 2050.

  16. Effect and kinetic mechanism of ultrasonic vibration on solidification of 7050 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Jiang, Ripeng; Li, Xiaoqian; Chen, Pinghu; Li, Ruiqing; Zhang, Xue

    2014-07-01

    The work described in this paper dealt with the effect of ultrasonic vibration on the solidification of 7050 aluminum alloy. Two experiments were carried out through introducing ultrasound into the semi-continuous direct-chill (DC) casting of aluminum alloy and into alloy solidifying in a crucible, respectively. Results show that ultrasonic vibration can refine grains in the whole cross-section of a billet in the first experiment and is able to increase the cooling rate within the temperature range from 625 °C to 590 °C in the other one. The mechanism of particle resonance caused by ultrasonic vibration was illustrated on the basis of theoretical analysis of the kinetics and energy conversion during the solidification. It is demonstrated that the kinetic energy of resonant particles are mainly from the latent heat energy of solidification, which can shorten the cooling time, inhibit the crystal growth and then lead to the grain refinement.

  17. Evaluation of Aluminum Alloy 2050-T84 Microstructure Mechanical Properties at Ambient and Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Hafley, Robert A.; Domack, Marcia S.; Hales, Stephen J.; Shenoy, Ravi N.

    2011-01-01

    Aluminum alloy 2050 is being considered for the fabrication of cryogenic propellant tanks to reduce the mass of future heavy-lift launch vehicles. The alloy is available in section thicknesses greater than that of the incumbent aluminum alloy, 2195, which will enable the designs with greater structural efficiency. While ambient temperature design allowable properties are available for alloy 2050, cryogenic properties are not available. To determine its suitability for use in cryogenic propellant tanks, tensile, compression and fracture tests were conducted on 4 inch thick 2050-T84 plate at ambient temperature and at -320 F. Various metallurgical analyses were also performed in order to provide an understanding of the compositional homogeneity and microstructure of 2050.

  18. Effect of Electromagnetic Treatment on Fatigue Resistance of 2011 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Mohin, M. A.; Toofany, H.; Babutskyi, A.; Lewis, A.; Xu, Y. G.

    2016-08-01

    Beneficial effects of the electromagnetic treatment on fatigue resistance were reported on several engineering alloys. These could be linked to the dislocation activity and the rearrangement of the crystal structure of the material under the electromagnetic field (EMF), resulting in delayed crack initiation. This paper presents an experimental study on the effect of pulsed electromagnetic treatment on the fatigue resistance of 2011 aluminum alloy. Circular cantilever specimens with loads at their ends were tested on rotating fatigue machine SM1090. Fatigue lives of treated and untreated specimens were analyzed and compared systematically. It has been found that the effect of the pulsed electromagnetic treatment on the fatigue resistance is dependent on the intensity of the pulsed EMF and the number of the treatment applied. Clear beneficial effect of the pulsed electromagnetic treatment on the fatigue resistance of the aluminum alloys has been observed, demonstrating a potential new technique to industries for fatigue life extension.

  19. Susceptibility of Aluminum Alloys to Corrosion in Simulated Fuel Blends Containing Ethanol

    SciTech Connect

    Thomson, Jeffery K; Pawel, Steven J; Wilson, Dane F

    2013-01-01

    The compatibility of aluminum and aluminum alloys with synthetic fuel blends comprised of ethanol and reference fuel C (a 50/50 mix of toluene and iso-octane) was examined as a function of water content and temperature. Commercially pure wrought aluminum and several cast aluminum alloys were observed to be similarly susceptible to substantial corrosion in dry (< 50 ppm water) ethanol. Corrosion rates of all the aluminum materials examined was accelerated by increased temperature and ethanol content in the fuel mixture, but inhibited by increased water content. Pretreatments designed to stabilize passive films on aluminum increased the incubation time for onset of corrosion, suggesting film stability is a significant factor in the mechanism of corrosion.

  20. Ultrasonic semi-solid coating soldering 6061 aluminum alloys with Sn-Pb-Zn alloys.

    PubMed

    Yu, Xin-ye; Xing, Wen-qing; Ding, Min

    2016-07-01

    In this paper, 6061 aluminum alloys were soldered without a flux by the ultrasonic semi-solid coating soldering at a low temperature. According to the analyses, it could be obtained that the following results. The effect of ultrasound on the coating which promoted processes of metallurgical reaction between the components of the solder and 6061 aluminum alloys due to the thermal effect. Al2Zn3 was obtained near the interface. When the solder was in semi-solid state, the connection was completed. Ultimately, the interlayer mainly composed of three kinds of microstructure zones: α-Pb solid solution phases, β-Sn phases and Sn-Pb eutectic phases. The strength of the joints was improved significantly with the minimum shear strength approaching 101MPa. PMID:26964943

  1. Effect of polymer coatings on fatigue strength of aluminum alloy 2024 box beams

    NASA Technical Reports Server (NTRS)

    Nordmark, G. E.; Kelsey, R. A.

    1972-01-01

    Previous investigators have shown that polymer coatings raise the fatigue strength of metals tested in air to about the same level as that of uncoated specimens tested in vacuum. The results are given of tests to determine if a polymer coating would improve the fatigue strength of built-up aluminum alloy members simulating aircraft construction. Aluminum alloy 2024-T4 riveted box beams were subjected to constant amplitude fatigue tests in air as well as in salt water fog. The coating did not improve the fatigue strength of beams tested in either environment. This is believed to result from the fact that most failures originated at rivet holes, which were isolated from both the coating and the environment.

  2. The role of hydrogen in hot-salt stress corrosion cracking of titanium-aluminum alloys

    NASA Technical Reports Server (NTRS)

    Ondrejcin, R. S.

    1971-01-01

    Additional support is presented for the previously proposed role of hydrogen as an embrittling agent in hot-salt stress corrosion cracking of titanium-aluminum alloys. The main source of hydrogen formed during the reactions of titanium alloys with hot salt was identified as water associated with the salt. Hydrogen is produced by the reaction of an intermediate (hydrogen halide) with the alloy rather than from metal-water reactions. The fracture mode of precracked tensile specimens was ductile when the specimens were tested in air, and brittle when tests were made in high-pressure hydrogen. Stressed titanium-aluminum alloys also were cracked by bombardment with hydrogen ions produced in a proton accelerator. The approximate concentrations of the hydrogen ions in the alloys were calculated.

  3. Effect of Strain Rate and Temperature Gradient on Warm Formability of Aluminum Alloy Sheet

    NASA Astrophysics Data System (ADS)

    Bagheriasl, R.; Ghavam, K.; Worswick, M. J.

    2011-08-01

    The effect of temperature gradient and forming speed on warm formability of aluminum alloy sheet has been studied using a coupled thermal mechanical finite element model of cup deep drawing. A user-defined material model was developed using the Bergstrom temperature and strain-rate dependant hardening model and Barlat YLD2000 anisotropic yield surface, which was implemented within LS-DYNA. The stress-strain curves for AA3003 at elevated temperatures and different strain rates were used to fit the Bergstrom hardening parameters. The anisotropy parameters were considered to be non-temperature dependant. The numerical model was validated against experiments from previous work and was found to accurately predict punch force for warm deep drawing. Increases in forming speed are shown to have a negative effect on formability. It is concluded that non-isothermal warm forming can be used to improve the formability of aluminum alloy sheet.

  4. Tribological Properties of Aluminum Alloy treated by Fine Particle Peening/DLC Hybrid Surface Modification

    NASA Astrophysics Data System (ADS)

    Amano, Y.; Nanbu, H.; Kameyama, Y.; Komotori, J.

    2010-06-01

    In order to improve the adhesiveness of the DLC coating, Fine Particle Peening (FPP) treatment was employed as pre-treatment of the DLC coating process. FPP treatment was performed using SiC shot particles, and then AA6061-T6 aluminum alloy was DLC-coated. A SiC-rich layer was formed around the surface of the aluminum alloy by the FPP treatment because small chips of shot particles were embedded into the substrate surface. Reciprocating sliding tests were conducted to measure the friction coefficients. While the DLC coated specimen without FPP treatment showed a sudden increase in friction coefficient at the early stage of the wear cycles, the FPP/DLC hybrid treated specimen maintained a low friction coefficient value during the test period. Further investigation revealed that the tribological properties of the substrate after the DLC coating were improved with an increase in the amount of Si at the surface.

  5. The Cleaning of OAB Universal Covers - An Origin of Smut in Aluminum Alloys

    SciTech Connect

    Shen, T

    2002-05-14

    The smut that appeared on the universal covers after the OAB cleaning process consists of sub-micron size aluminum particles originating from the machining of these parts prior to cleaning. The rigorous gross and precision cleanings with Brulin in the OAB cleaning process could not completely wash these fine particles away from the surfaces. However, applying a phosphoric acid etch before the cleaning helped to remove these fine aluminum particles. Experimental results again showed that an acid etching before cleaning is essential in preventing the occurrence of smut in aluminum alloy after gross/precision cleaning. A mechanism, based on the electrostatic {zeta}-potential, is proposed to explain the occurrence of smut that is often encountered during the cleaning of aluminum alloys.

  6. Brazeability of a 3003 Aluminum alloy with Al-Si-Cu-based filler metals

    NASA Astrophysics Data System (ADS)

    Tsao, L. C.; Weng, W. P.; Cheng, M. D.; Tsao, C. W.; Chuang, T. H.

    2002-08-01

    Al-Si-Cu-based filler metals have been used successfully for brazing 6061 aluminum alloy as reported in the authors’ previous studies. For application in heat exchangers during manufacturing, the brazeability of 3003 aluminum alloy with these filler metals is herein further evaluated. Experimental results show that even at such a low temperature as 550 °C, the 3003 alloys can be brazed with the Al-Si-Cu fillers and display bonding strengths that are higher than 77 MPa as well. An optimized 3003 joint is attained in the brazements with the innovative Al-7Si-20Cu-2Sn-1Mg filler metal at 575 °C for 30 min, which reveals a bonding strength capping the 3003 Al matrix.

  7. Acoustic emission location on aluminum alloy structure by using FBG sensors and PSO method

    NASA Astrophysics Data System (ADS)

    Lu, Shizeng; Jiang, Mingshun; Sui, Qingmei; Dong, Huijun; Sai, Yaozhang; Jia, Lei

    2016-04-01

    Acoustic emission location is important for finding the structural crack and ensuring the structural safety. In this paper, an acoustic emission location method by using fiber Bragg grating (FBG) sensors and particle swarm optimization (PSO) algorithm were investigated. Four FBG sensors were used to form a sensing network to detect the acoustic emission signals. According to the signals, the quadrilateral array location equations were established. By analyzing the acoustic emission signal propagation characteristics, the solution of location equations was converted to an optimization problem. Thus, acoustic emission location can be achieved by using an improved PSO algorithm, which was realized by using the information fusion of multiple standards PSO, to solve the optimization problem. Finally, acoustic emission location system was established and verified on an aluminum alloy plate. The experimental results showed that the average location error was 0.010 m. This paper provided a reliable method for aluminum alloy structural acoustic emission location.

  8. Superhydrophobic aluminum alloy surfaces by a novel one-step process.

    PubMed

    Saleema, N; Sarkar, D K; Paynter, R W; Chen, X-G

    2010-09-01

    A simple one-step process has been developed to render aluminum alloy surfaces superhydrophobic by immersing the aluminum alloy substrates in a solution containing NaOH and fluoroalkyl-silane (FAS-17) molecules. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle measurements have been performed to characterize the morphological features, chemical composition and superhydrophobicity of the surfaces. The resulting surfaces provided a water contact angle as high as ∼162° and a contact angle hysteresis as low as ∼4°. The study indicates that it is possible to fabricate superhydrophobic aluminum surfaces easily and effectively without involving the traditional two-step processes. PMID:20812666

  9. Precision Forging Technological Optimization for 7075 Aluminum Alloy Complex Component with Limbs

    NASA Astrophysics Data System (ADS)

    Lang, Li-hui; Xu, Ai-jun; Li, Feng

    2012-02-01

    Aluminum alloy complex components with limbs, such as antitorque arms, are difficult to manufacture because of their complicated shapes and high requirements in terms of mechanical properties. To form 7075 aluminum alloy antitorque arms precisely, two forming schemes with different billet shapes were used to simulate the precision forming process and study the metal flow laws using DEFORM™-3D software. The simulated results show that the second forming scheme (with a two preformed limb billet) significantly improved the metal filling formability and flowing uniformity compared with the simpler solid billet case. Moreover, this scheme also significantly increased material utilization, and the required forming load was only 30% of the first scheme. The experimental results also showed that this scheme can obtain the necessary component with dimensional accuracy and quality in good agreement with all the technical requirements.

  10. Second- and third-order elastic coefficients in polycrystalline aluminum alloy AMg6

    NASA Astrophysics Data System (ADS)

    Volkov, A. D.; Kokshaiskii, A. I.; Korobov, A. I.; Prokhorov, V. M.

    2015-11-01

    All independent second- and third-order elastic coefficients were measured in the isotropic polycrystalline aluminum alloy AMg6 (Al-Mg-Mn system) using the Ritec RAM-5000 SNAP SYSTEM ultrasonic automated complex operating in the pulsed mode. The third-order elastic coefficients were determined using the Thurston-Bragger method from the experimentally measured velocity of shear and longitudinal elastic waves in AMg6 alloy as a function of uniaxial compression.

  11. Self-Reacting Friction Stir Welding for Aluminum Alloy Circumferential Weld Applications

    NASA Technical Reports Server (NTRS)

    Bjorkman, Gerry; Cantrell, Mark; Carter, Robert

    2003-01-01

    Friction stir welding is an innovative weld process that continues to grow in use, in the commercial, defense, and space sectors. It produces high quality and high strength welds in aluminum alloys. The process consists of a rotating weld pin tool that plasticizes material through friction. The plasticized material is welded by applying a high weld forge force through the weld pin tool against the material during pin tool rotation. The high weld forge force is reacted against an anvil and a stout tool structure. A variation of friction stir welding currently being evaluated is self-reacting friction stir welding. Self-reacting friction stir welding incorporates two opposing shoulders on the crown and root sides of the weld joint. In self-reacting friction stir welding, the weld forge force is reacted against the crown shoulder portion of the weld pin tool by the root shoulder. This eliminates the need for a stout tooling structure to react the high weld forge force required in the typical friction stir weld process. Therefore, the self-reacting feature reduces tooling requirements and, therefore, process implementation costs. This makes the process attractive for aluminum alloy circumferential weld applications. To evaluate the application of self-reacting friction stir welding for aluminum alloy circumferential welding, a feasibility study was performed. The study consisted of performing a fourteen-foot diameter aluminum alloy circumferential demonstration weld using typical fusion weld tooling. To accomplish the demonstration weld, weld and tack weld development were performed and fourteen-foot diameter rings were fabricated. Weld development consisted of weld pin tool selection and the generation of a process map and envelope. Tack weld development evaluated gas tungsten arc welding and friction stir welding for tack welding rings together for circumferential welding. As a result of the study, a successful circumferential demonstration weld was produced leading

  12. Time-dependent corrosion fatique crack propagation in 7000 series aluminum alloys. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Mason, Mark E.

    1995-01-01

    The goal of this research is to characterize environmentally assisted subcritical crack growth for the susceptible short-longitudinal orientation of aluminum alloy 7075-T651, immersed in acidified and inhibited NaCl solution. This work is necessary in order to provide a basis for incorporating environmental effects into fatigue crack propagation life prediction codes such as NASA-FLAGRO (NASGRO). This effort concentrates on determining relevant inputs to a superposition model in order to more accurately model environmental fatigue crack propagation.

  13. Microstructure-sensitive plasticity and fatigue modeling of extruded 6061 aluminum alloys

    NASA Astrophysics Data System (ADS)

    McCullough, Robert Ross

    In this study, the development of fatigue failure and stress anisotropy in light weight ductile metal alloys, specifically Al-Mg-Si aluminum alloys, was investigated. The experiments were carried out on an extruded 6061 aluminum alloy. Reverse loading experiments were performed up to a prestrain of 5% in both tension-followed-by-compression and compression-followed-by-tension. The development of isotropic and kinematic hardening and subsequent anisotropy was indicated by the observation of the Bauschinger effect phenomenon. Experimental results show that 6061 aluminum alloy exhibited a slight increase in the kinematic hardening versus applied prestrain. However, the ratio of kinematic-to-isotropic hardening remained near unity. An internal state variable (ISV) plasticity and damage model was used to capture the evolution of the anisotropy for the as-received T6 and partially annealed conditions. Following the stress anisotropy experiments, the same extruded 6061 aluminum alloy was tested under fully reversing, strain-controlled low cycle fatigue at up to 2.5% strain amplitudes and two heat treatment conditions. Observations were made of the development of striation fields up to the point of nucleation at cracked and clustered precipitants and free surfaces through localized precipitant slip band development. A finite element enabled micro-mechanics study of fatigue damage development of local strain field in the presence of hard phases was conducted. Both the FEA and experimental data sets were utilized in the implementation of a multi-stage fatigue model in order to predict the microstructure response, including fatigue nucleation and propagation contributions on the total fatigue life in AA6061. Good correlation between experimental and predicted results in the number of cycles to final failure was observed. The AA6061 material maintained relatively consistent low cycle fatigue performance despite two different heat treatments.

  14. The filtration of molten 1XXX series aluminum alloys with rigid media tube filter

    SciTech Connect

    Hoshino, K.; Nishizaka, T.; Kakimoto, K.; Yoshida, T.

    1996-10-01

    Recently it has been increasing that molten 1XXX series aluminum alloys are filtered by Rigid Media Tube Filters (RMF). In that case, it occasionally happens that the pressure drop across the RMF rapidly increases in its relatively early stage of use. The authors have investigated inclusions captured in the RMF and conducted some model tests to define the cause. Consequently the mechanism of the rapid increase of pressure drop is given.

  15. Correlation between shear punch and tensile data for neutron-irradiated aluminum alloys

    SciTech Connect

    Hamilton, M.L.; Edwards, D.J.; Toloczko, M.B.

    1995-04-01

    This work was performed to determine whether shear punch and tensile data obtained on neutron irradiated aluminum alloys exhibited the same type of relationship as had been seen in other work and to assess the validity of extrapolating the results to proton-irradiated alloys. This work was also meant to be the first of a series of similar test matrices designed to determine whether the shear punch/tensile relationship varied or was the same for different alloy classes.

  16. A potentiostatic study of the corrosion behavior of anodized and nonanodized aluminum alloy.

    PubMed

    White, K C; Svare, C W; Taylor, T D

    1985-06-01

    The clinical implication of this study is that some improvement in the corrosion resistance of denture bases made with aluminum alloy D-214 may be obtained by anodization. However, since this study does not exactly duplicate an oral environment or take into consideration the variation in oral environments, it cannot be assumed that the additional corrosion resistance would be discernible in a particular patient. PMID:3859652

  17. NBS: Nondestructive evaluation of nonuniformities in 2219 aluminum alloy plate: Relationship to processing

    NASA Technical Reports Server (NTRS)

    Swartzendruber, L.; Boettinger, W.; Ives, L.; Coriell, S.; Ballard, D.; Laughlin, D.; Clough, R.; Biancanieilo, F.; Blau, P.; Cahn, J.

    1980-01-01

    The compositional homogeneity, microstructure, hardness, electrical conductivity and mechanical properties of 2219 aluminum alloy plates are influenced by the process variables during casting, rolling and thermomechanical treatment. The details of these relationships wre investigated for correctly processed 2219 plate as well as for deviations caused by improper quenching after solution heat treatment. Primary emphasis was been placed on the reliability of eddy current electrical conductivity and hardness as NDE tools to detect variations in mechanical properties.

  18. Determination of design allowable properties. Fracture of 2219-T87 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Engstrom, W. L.

    1972-01-01

    A literature survey was conducted to provide a comprehensive report of available valid data on tensile properties, fracture toughness, fatigue crack propagation, and sustained load behavior of 2219-T87 aluminum alloy base metal and weldments, as applicable to manned spacecraft tankage. Most of the data found were from tests conducted at room temperature, -320 F and -423 F. Data are presented in graphical and tabular form, and areas in which data are lacking are established.

  19. The variation of hydrophobicity of aluminum alloy by nitrogen and argon ion implantation

    NASA Astrophysics Data System (ADS)

    Do, Sang Cheol; Kim, Ki Wook; Jeong, Ji Hwan

    2015-04-01

    Nitrogen and argon ions were irradiated on the surface of aluminum alloy. Ion irradiation appeared to increase contact angle of the metallic specimens. In order to investigate the factors affecting the changes of contact angles, changes in the characteristics of the surfaces were examined using SEM, AFM, and X-ray diffraction. The contact angle increased due to surface composition changes and surface roughness changes.

  20. Multistage Fatigue Modeling of Cast A356-T6 and A380-F Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Xue, Y.; Burton, C. L.; Horstemeyer, M. F.; McDowell, D. L.; Berry, J. T.

    2007-08-01

    This article presents a microstructure-based multistage fatigue (MSF) model extended from the model developed by McDowell et al.[1,2] to an A380-F aluminum alloy to consider microstructure-property relations of descending order, signifying deleterious effects of defects/discontinuities: (1) pores or oxides greater than 100 μm, (2) pores or oxides greater than 50 μm near the free surface, (3) a high porosity region with an area greater than 200 μm, and (4) oxide film of an area greater than 10,000 μm2. These microconstituents, inclusions, or discontinuities represent different casting features that may dominate fatigue life at stages of fatigue damage evolutions. The incubation life is estimated using a modified Coffin Mansion law at the microscale based on the microplasticity at the discontinuity. The microstructurally small crack (MSC) and physically small crack (PSC) growth was modeled using the crack tip displacement as the driving force, which is affected by the porosity and dendrite cell size (DCS). When the fatigue damage evolves to several DCSs, cracks behave as long cracks with growth subject to the effective stress intensity factor in linear elastic fracture mechanics. Based on an understanding of the microstructures of A380-F and A356-T6 aluminum alloys, an engineering treatment of the MSF model was introduced for A380-F aluminum alloys by tailoring a few model parameters based on the mechanical properties of the alloy. The MSF model is used to predict the upper and lower bounds of the experimental fatigue strain life and stress life of the two cast aluminum alloys.

  1. The application of acoustic emission technique to fatigue crack measurement. [in aluminum alloys

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Davis, W. T.; Crews, J. H., Jr.

    1974-01-01

    The applicability of acoustic emission technique to measure fatigue cracks in aluminum alloy specimens was investigated. There are several variables, such as the metallurgical and the physical treatment of the specimen, that can affect the level of acoustic activity of a fatigue specimen. It is therefore recommended that the acoustic emission technique be supplemented by other nondestructive evaluation methods to obtain quantitative data on crack growth.

  2. Combined Beam-column Stresses of Aluminum-alloy Channel Sections

    NASA Technical Reports Server (NTRS)

    Gottlieb, R; Thompson, T M; Witt, E C

    1939-01-01

    The results of a research program to obtain design data on the strength of open-channel aluminum-alloy sections subjected to combined column and beam action. The results of the tests of about 70 specimens were graphed for stresses due to axial load and stresses due to bending loading as functions of length to radius of gyration of the specimens. From these graphs a design chart was derived that is suitable for ready use.

  3. Time-dependent corrosion fatique crack propagation in 7000 series aluminum alloys. M.S. Thesis

    SciTech Connect

    Mason, M.E.

    1995-10-01

    The goal of this research is to characterize environmentally assisted subcritical crack growth for the susceptible short-longitudinal orientation of aluminum alloy 7075-T651, immersed in acidified and inhibited NaCl solution. This work is necessary in order to provide a basis for incorporating environmental effects into fatigue crack propagation life prediction codes such as NASA-FLAGRO (NASGRO). This effort concentrates on determining relevant inputs to a superposition model in order to more accurately model environmental fatigue crack propagation.

  4. The plastic compressibility of 7075-T651 aluminum-alloy plate

    NASA Technical Reports Server (NTRS)

    Freed, A. D.; Sandor, B. I.

    1986-01-01

    The change in volume, and therefore the change in mass density, of an aluminum alloy was measured in uniaxial tension using clip-on extensometers. The experimental data do not agree with the assumption of plastic incompressibility found in the classical theories of plasticity. In fact, the elastic and plastic volume changes are of the same order of magnitude. Plastic anisotropy is thought to be the prime cause of this plastic compressibility.

  5. Anticorrosive Solution of 6201 Aluminum Alloy used in STEG Company's Overhead Transmission Lines

    NASA Astrophysics Data System (ADS)

    Rhaiem, E.; Bouraoui, T.; Elhalouani, F.

    2010-11-01

    Nowadays, aluminum alloys are widely used as conductor in power electrical transmission lines mainly due to their good physicochemical and mechanical properties as well as their financial profitability. Nonetheless, aluminium alloys conductors, which normally fulfil standard requirements, can fail under severe service conditions in relationship with environmental factors such as humidity, industrial pollution or marine salts present in the atmosphere. In this case, an anticorrosive solution must be considered for an optimal use. This study reports the result of electrochemical polarization and scanning electron microscopy (SEM) on the corrosion inhibition of AA 6201 aluminum alloys exploited in High Electric conductors, using zincating deposition as inhibition. The electrochemical measurements of aluminum alloys after Zn coating of aluminum and varied immersion in 0.5M NaCl and in 0.5M NaCl + 0.1M Na2SO4 give a significant decrease in the corrosion current densities (icorr.), and an increase in corrosion potential (Ecorr). The thin film on the specimens has been proven by morphology study using SEM.

  6. Effects of Forging Process Parameters on Microstructure Evolution of Aluminum Alloy 7050

    SciTech Connect

    Yi Youping; Shi Yan; Yang Jihui; Lin Yongcheng

    2007-04-07

    The objective of this work is to investigate the behavior of microstructure evolution of aluminum alloy 7050 under the condition of different forging process parameters by means of combining materials physical model with finite element code. For the purpose of establishing constitutive equation and physical model of microstructure evolution, the isothermal compression test were performed by machine Gleeble 1500 on the condition of temperatures ranging from 250 deg. C to 450 deg. C and constant strain rates of 0.01s-1, 0.1s-1, 1s-1 and 10s-1. The behaviors of microstructure evolutions of aluminum alloy 7050 under difference process parameters were studied by metallographic observations. The experiment results showed that recrystallization during forming process occurred at the critical strain and the volume fraction of recrystallization changed with the temperature and strain rate. According to the results of isothermal compression test, a constitutive equation and an empirical model of DRX were obtained. A finite element code DEFORM 3D was used to analyze the influence of different forging process parameters on the behavior of microstructure evolution in details. The present model and simulation method can be served as a useful tool to predict and control the properties and shape of aluminum alloy 7050 components during forging.

  7. A hot-cracking mitigation technique for welding high-strength aluminum alloy

    SciTech Connect

    Yang, Y.P.; Dong, P.; Zhang, J.; Tian, X.

    2000-01-01

    A hot-cracking mitigation technique for gas tungsten arc welding (GTAW) of high-strength aluminum alloy 2024 is presented. The proposed welding technique incorporates a trailing heat sink (an intense cooling source) with respect to the welding torch. The development of the mitigation technique was based on both detailed welding process simulation using advanced finite element techniques and systematic laboratory experiments. The finite element methods were used to investigate the detailed thermomechanical behavior of the weld metal that undergoes the brittle temperature range (BTR) during welding. As expected, a tensile deformation zone within the material BTR region was identified behind the weld pool under conventional GTA welding process conventional GTA welding process conditions for the aluminum alloy studied. To mitigate hot cracking, the tensile zone behind the weld pool must be eliminated or reduce to a satisfactory level if the weld metal hot ductility cannot be further improved. With detailed computational modeling, it was found that by the introduction of a trailing heat sink at some distance behind the welding arc, the tensile strain rate with respect to temperature in the zone encompassing the BTR region can be significantly reduced. A series of parametric studies were also conducted to derive optimal process parameters for the trailing heat sink. The experimental results confirmed the effectiveness of the trailing heat sink technique. With a proper implementation of the trailing heat sink method, hot cracking can be completely eliminated in welding aluminum alloy 2024 (AA 2024).

  8. Experimental Study and Numerical Verification of Heat Transfer in Squeeze Casting of Aluminum Alloy A443

    NASA Astrophysics Data System (ADS)

    Sun, Zhizhong; Hu, Henry; Niu, Xiaoping

    2012-12-01

    As an effective tool, simulation helps do the analysis and optimization in advance and undertake preventive action. A critical portion of casting simulation is the heat transfer at the metal/mold interface. However, it is difficult to determine the values of interfacial heat-transfer coefficients (IHTCs) in squeeze casting of aluminum alloys due to many influence factors. In this work, IHTCs were determined by using the inverse algorithm based on measured temperature histories and finite-difference analysis in a five-step squeeze casting of aluminum alloy A443. The results showed the IHTCs initially reached a maximum peak value followed by a gradually decline to a lower level. Similar characteristics of IHTC peak values were also observed at 30, 60, and 90 MPa applied pressures. With the applied pressure of 60 MPa, the peak IHTC values of aluminum alloy A443 from steps 1 to 5 varied from 5629 W/m2K to 9419 W/m2K. The comparison of the predicted cooling curves with the experimental measurement manifested the cooling temperatures calculated by the IHTC values determined in the current study were in the best agreement with experimental ones. The verification of the determined IHTC values demonstrates that the inverse algorithm is an effective tool for determination of the IHTC at the squeeze casting-die interface.

  9. High Strength and Compatible Aluminum Alloy for Hydrogen-Peroxide Fuel Tanks

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2004-01-01

    This paper describes the development of a new high strength and Hydrogen Peroxide (HP) propellant compatible aluminum alloy for NASA Hyper-X vehicle's fuel tanks and structures. The tensile strength of the new alloy is more than 3 times stronger than the conventional 5254 alloy while it still maintains HP compatibility similar to 5254 (Class 1 category). The alloy development strategy consists of selecting certain rare earth and transition metals, with unique electrochemical properties, that will not act as catalysts to decompose liquid HP at the atomic level. Such elements will added to the aluminum alloy and the mixture will be cast and rolled into thin sheet metals. Test coupons are machined from sheet metals for HP long-term exposure testing and mechanical properties testing. In addition, the ability to weld the new alloy using Friction Stir Welding has also been explored. Currently, aluminum alloy 5254 is the state-of-the-art material for HP storage, but its yield strength is very low (420 ksi) and may not be suitable for the development of light-weight fuel tanks for Hyper-X vehicles. The new high strength and HP compatible alloy could represent an enabling material technology for NASA's Hyper-X vehicles, where flight weight reduction is a critical requirement. These X-planes are currently under studied as air-breathing hypersonic research vehicles featuring a lifting body configuration with a Rocket Based Combined Cycle (RBCC) engine system.

  10. Ultrasonic Impact Treatment to Improve Stress Corrosion Cracking Resistance of Welded Joints of Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Yu, J.; Gou, G.; Zhang, L.; Zhang, W.; Chen, H.; Yang, Y. P.

    2016-07-01

    Stress corrosion cracking is one of the major issues for welded joints of 6005A-T6 aluminum alloy in high-speed trains. High residual stress in the welded joints under corrosion results in stress corrosion cracking. Ultrasonic impact treatment was used to control the residual stress of the welded joints of 6005A-T6 aluminum alloy. Experimental tests show that ultrasonic impact treatment can induce compressive longitudinal and transverse residual stress in the welded joint, harden the surface, and increase the tensile strength of welded joints. Salt-fog corrosion tests were conducted for both an as-welded sample and an ultrasonic impact-treated sample. The surface of the treated sample had far fewer corrosion pits than that of the untreated sample. The treated sample has higher strength and lower tensile residual stress than the untreated sample during corrosion. Therefore, ultrasonic impact treatment is an effective technique to improve the stress corrosion cracking resistance of the welded joints of 6005A-T6 aluminum alloy.

  11. Ultrasonic Impact Treatment to Improve Stress Corrosion Cracking Resistance of Welded Joints of Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Yu, J.; Gou, G.; Zhang, L.; Zhang, W.; Chen, H.; Yang, Y. P.

    2016-06-01

    Stress corrosion cracking is one of the major issues for welded joints of 6005A-T6 aluminum alloy in high-speed trains. High residual stress in the welded joints under corrosion results in stress corrosion cracking. Ultrasonic impact treatment was used to control the residual stress of the welded joints of 6005A-T6 aluminum alloy. Experimental tests show that ultrasonic impact treatment can induce compressive longitudinal and transverse residual stress in the welded joint, harden the surface, and increase the tensile strength of welded joints. Salt-fog corrosion tests were conducted for both an as-welded sample and an ultrasonic impact-treated sample. The surface of the treated sample had far fewer corrosion pits than that of the untreated sample. The treated sample has higher strength and lower tensile residual stress than the untreated sample during corrosion. Therefore, ultrasonic impact treatment is an effective technique to improve the stress corrosion cracking resistance of the welded joints of 6005A-T6 aluminum alloy.

  12. Advanced powder metallurgy aluminum alloys via rapid solidification technology, phase 2

    NASA Technical Reports Server (NTRS)

    Ray, Ranjan; Jha, Sunil C.

    1987-01-01

    Marko's rapid solidification technology was applied to processing high strength aluminum alloys. Four classes of alloys, namely, Al-Li based (class 1), 2124 type (class 2), high temperature Al-Fe-Mo (class 3), and PM X7091 type (class 4) alloy, were produced as melt-spun ribbons. The ribbons were pulverized, cold compacted, hot-degassed, and consolidated through single or double stage extrusion. The mechanical properties of all four classes of alloys were measured at room and elevated temperatures and their microstructures were investigated optically and through electron microscopy. The microstructure of class 1 Al-Li-Mg alloy was predominantly unrecrystallized due to Zr addition. Yield strengths to the order of 50 Ksi were obtained, but tensile elongation in most cases remained below 2 percent. The class 2 alloys were modified composition of 2124 aluminum alloy, through addition of 0.6 weight percent Zr and 1 weight percent Ni. Nickel addition gave rise to a fine dispersion of intermetallic particles resisting coarsening during elevated temperature exposure. The class 2 alloy showed good combination of tensile strength and ductility and retained high strength after 1000 hour exposure at 177 C. The class 3 Al-Fe-Mo alloy showed high strength and good ductility both at room and high temperatures. The yield and tensile strength of class 4 alloy exceeded those of the commercial 7075 aluminum alloy.

  13. Process Modeling of Low-Pressure Die Casting of Aluminum Alloy Automotive Wheels

    NASA Astrophysics Data System (ADS)

    Reilly, C.; Duan, J.; Yao, L.; Maijer, D. M.; Cockcroft, S. L.

    2013-09-01

    Although on initial inspection, the aluminum alloy automotive wheel seems to be a relatively simple component to cast based on its shape, further insight reveals that this is not the case. Automotive wheels are in a select group of cast components that have strict specifications for both mechanical and aesthetic characteristics due to their important structural requirements and their visibility on a vehicle. The modern aluminum alloy automotive wheel continues to experience tightened tolerances relating to defects to improve mechanical performance and/or the physical appearance. Automotive aluminum alloy wheels are assessed against three main criteria: wheel cosmetics, mechanical performance, and air tightness. Failure to achieve the required standards in any one of these categories will lead to the wheel either requiring costly repair or being rejected and remelted. Manufacturers are becoming more reliant on computational process modeling as a design tool for the wheel casting process. This article discusses and details examples of the use of computational process modeling as a predictive tool to optimize the casting process from the standpoint of defect minimization with the emphasis on those defects that lead to failure of aluminum automotive wheels, namely, macroporosity, microporosity, and oxide films. The current state of applied computational process modeling and its limitations with regard to wheel casting are discussed.

  14. Characteristics of laser beam welds of age-hardenable 6061-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Hirose, Akio; Kobayashi, Kojiro F.

    2003-03-01

    Laser beam welding is attractive for joining age-hardenable aluminum alloys, because its low over-all heat input results in a narrow weld heat affected zone (HAZ), where softening caused by dissolution of age precipitates occurs. In the present work, 1mm-thick 6061-T6 aluminum alloy plates were welded using a 2.5 kW CO2 laser and it was experimentally proved that the width of the softened region in the laser beam weld was less than 1/7 that of a TIG weld. Moreover the hardness in the softened region of the laser beam weld was found to be almost fully recovered to the base metal hardness by applying a post-weld aging treatment at 443 K for 28.8 ks without solution annealing unlike the TIG weld. These results characterize the advantage of laser beam welding in joining of the age-hardenable aluminum alloy as compared with the conventional arc welding. The hardness distributions in the HAZ were theoretically evaluated based on kinetic equations describing the dissolution of hardening β' (Mg2Si) precipitates and the precipitation of non-hardening β' (Mg2Si) precipitates during the weld thermal cycles to quantitatively prove above mentioned advantageous characteristics of laser beam welding.

  15. A method for studying weld fusion boundary microstructure evolution in aluminum alloys

    SciTech Connect

    Kostrivas, A.; Lippold, J.C.

    2000-01-01

    Aluminum alloys may exhibit a variety of microstructures within the fusion zone adjacent to the fusion boundary. Under conventional weld solidification conditions, epitaxial nucleation occurs off grains in the heat-affected zone (HAZ) and solidification proceeds along preferred growth directions. In some aluminum alloys, such as those containing Li and Zr, a nondendritic equiaxed grain zone (EQZ) has been observed along the fusion boundary that does not nucleate epitaxially from the HAZ substrate. The EQZ has been the subject of considerable study because of its susceptibility to cracking during initial fabrication and repair. The motivation of this investigation was to develop a technique that would allow the nature and evolution of the fusion boundary to be studied under controlled thermal conditions. A melting technique was developed to simulate the fusion boundary of aluminum alloys using the Gleeble{reg{underscore}sign} thermal simulator. Using a steel sleeve to contain the aluminum, samples wee heated to incremental temperatures above the solidus temperature of a number of alloys. In Alloy 2195, a 4Cu-1Li alloy, an EQZ could be formed by heating in the temperature range approximately from 630--640 C. At temperatures above 640 C, solidification occurred by the normal epitaxial nucleation and growth mechanism. Fusion boundary behavior was also studied in Alloys 5454-H34, 6061-T6 and 2219-T8. Nucleation in these alloys was observed to be epitaxial. Details of the technique and its effectiveness for performing controlled melting experiments at incremental temperatures above the solidus are described.

  16. Crack-tip-opening angle measurements and crack tunneling under stable tearing in thin sheet 2024-T3 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Dawicke, D. S.; Sutton, M. A.

    1993-01-01

    The stable tearing behavior of thin sheets 2024-T3 aluminum alloy was studied for middle crack tension specimens having initial cracks that were: flat cracks (low fatigue stress) and 45 degrees through-thickness slant cracks (high fatigue stress). The critical crack-tip-opening angle (CTOA) values during stable tearing were measured by two independent methods, optical microscopy and digital image correlation. Results from the two methods agreed well. The CTOA measurements and observations of the fracture surfaces showed that the initial stable tearing behavior of low and high fatigue stress tests is significantly different. The cracks in the low fatigue stress tests underwent a transition from flat-to-slant crack growth, during which the CTOA values were high and significant crack tunneling occurred. After crack growth equal to about the thickness, CTOA reached a constant value of 6 deg and after crack growth equal to about twice the thickness, crack tunneling stabilized. The initial high CTOA values, in the low fatigue crack tests, coincided with large three-dimensional crack front shape changes due to a variation in the through-thickness crack tip constraint. The cracks in the high fatigue stress tests reach the same constant CTOA value after crack growth equal to about the thickness, but produced only a slightly higher CTOA value during initial crack growth. For crack growth on the 45 degree slant, the crack front and local field variables are still highly three-dimensional. However, the constant CTOA values and stable crack front shape may allow the process to be approximated with two-dimensional models.

  17. Facile transition from hydrophilicity to superhydrophilicity and superhydrophobicity on aluminum alloy surface by simple acid etching and polymer coating

    NASA Astrophysics Data System (ADS)

    Liu, Wenyong; Sun, Linyu; Luo, Yuting; Wu, Ruomei; Jiang, Haiyun; Chen, Yi; Zeng, Guangsheng; Liu, Yuejun

    2013-09-01

    The transition from the hydrophilic surface to the superhydrophilic and superhydrophobic surface on aluminum alloy via hydrochloric acid etching and polymer coating was investigated by contact angle (CA) measurements and scanning electron microscope (SEM). The effects of etching and polymer coating on the surface were discussed. The results showed that a superhydrophilic surface was facilely obtained after acid etching for 20 min and a superhydrophobic surface was readily fabricated by polypropylene (PP) coating after acid etching. When the etching time was 30 min, the CA was up to 157̊. By contrast, two other polymers of polystyrene (PS) and polypropylene grafting maleic anhydride (PP-g-MAH) were used to coat the aluminum alloy surface after acid etching. The results showed that the CA was up to 159̊ by coating PP-g-MAH, while the CA was only 141̊ by coating PS. By modifying the surface with the silane coupling agent before PP coating, the durability and solvent resistance performance of the superhydrophobic surface was further improved. The micro-nano concave-convex structures of the superhydrophilic surface and the superhydrophobic surface were further confirmed by scanning electron microscope (SEM). Combined with the natural hydrophilicity of aluminum alloy, the rough micro-nano structures of the surface led to the superhydrophilicity of the aluminum alloy surface, while the rough surface structures led to the superhydrophobicity of the aluminum alloy surface by combination with the material of PP with the low surface free energy.

  18. Fatigue damage assessment in 7075 and 7050 aluminum alloys at low cyclic stresses

    NASA Astrophysics Data System (ADS)

    Malast, Mary Kathryn

    Dynamic loads from buffeting, shock waves, and separated flow cause aircraft structural fatigue. Increases in aircraft performance cause sonic high cycle fatigue (HCF) in structural components. The accuracy of HCF damage predictions and fracture mechanics analysis has been limited in the past by the maximum cyclic rate of fatigue test equipment. Constant load amplitude axial fatigue data has previously been acquired at rates on the order of 100 Hz or less. Understanding HCF damage mechanisms has been hindered by this limitation. Recent improvements in test technology and analysis methods have made axial HCF experiments practical. X-ray diffraction line broadening analysis is used here to quantify microstructural changes in 7075-T651 and 7050-T7451 precipitation hardened aluminum alloys after exposure to fatigue loading. The Stokes deconvolution and Warren-Averbach method are used to compute size and strain broadening from line broadened X-ray diffraction patterns. Changes in domain size, strain, domain size anisotropy, and particle size distribution are used to assess fatigue in the alloys. Mechanisms which account for the observed microstructural changes are proposed. Peak splitting produces double maxima in the X-ray diffraction data. Double maxima are previously reported in the literature. Possible sources of the double maxima in precipitation hardened aluminum alloys are considered. In addition to assessing fatigue related microstructural changes in 7075 and 7050 aluminum alloys, the line broadening method applied to fatigue related assessment of these alloys is determined to be a promising approach. The method may have application to evaluation of aircraft in production. Possible applications and future work needed to apply the line broadening method to damage evaluation of engineering problems are proposed.

  19. Fracture mechanics and surface chemistry studies of fatigue crack growth in an aluminum alloy

    NASA Astrophysics Data System (ADS)

    Wei, R. P.; Pao, P. S.; Hart, R. G.; Weir, T. W.; Simmons, G. W.

    1980-12-01

    Fracture mechanics and surface chemistry studies were carried out to develop further understanding of the influence of water vapor on fatigue crack growth in aluminum alloys. The room temperature fatigue crack growth response was determined for 2219-T851 aluminum alloy exposed to water vapor at pressures from 1 to 30 Pa over a range of stress intensity factors ( K). Data were also obtained in vacuum (at < 0.50 μPa), and dehumidified argon. The test results showed that, at a frequency of 5 Hz, the rate of crack growth is essentially unaffected by water vapor until a threshold pressure is reached. Above this threshold, the rates increased, reaching a maximum within one order of magnitude increase in vapor pressure. This maximum crack growth rate is equal to that obtained in air (40 to 60 pct relative humidity), distilled water and 3.5 pct NaCl solution on the same material. Parallel studies of the reactions of water vapor with fresh alloy surfaces (produced either by in situ impact fracture or by ion etching) were made by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The extent of surface reaction was monitored by changes in the oxygen AES and XPS signals. Correlation between the fatigue crack growth response and the surface reaction kinetics has been made, and is consistent with a transport-limited model for crack growth. The results also suggest that enhancement of fatigue crack growth by water vapor in the aluminum alloys occurs through a “hydrogen embrittle ment” mechanism.

  20. Effect of cooling rate on microstructure of friction-stir welded AA1100 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Yi, D.; Mironov, S.; Sato, Y. S.; Kokawa, H.

    2016-06-01

    In this work, the microstructural changes occurring during cooling of friction-stir welded aluminum alloy AA1100 were evaluated. To this end, friction-stir welding (FSW) was performed in a wide range of cooling rates of 20-62 K/s and the evolved microstructures were studied by using electron backscatter diffraction. Below 0.6 Tm (Tm being the melting point), the stir zone material was found to experience no significant changes during cooling. At higher FSW temperatures, however, notable changes occurred in the welded material, including grain growth, sharpening of texture, reduction of the fraction of high-angle boundaries and material softening.

  1. Investigations of conductive polymer coatings for corrosion protection of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Racicot, Robert James

    The anti-corrosion properties of a novel double strand conductive polymer coating on aluminum alloys in salt environments as a possible replacement for chromium conversion coatings was investigated. The conductive coating consisted of a double helix backbone structure of polyaniline wrapped with an esterified polyacrylic acid strand. This polymer complex offers advantages over other conductive polymer systems in material stability and processability. The polymer is soluble in single organic solvents and was sprayed onto square AA7075-T6 and AA2024-T3 aluminum alloy samples. The coatings were investigated for corrosion protection properties using cyclic polarization, electrochemical impedance spectroscopy (EIS) and long term exposure in aggressive salt environments. The polymer coated samples were tested against two commercial chromate conversion coatings and uncoated alloy samples. The cyclic polarization tests show a two order of magnitude lowering of the corrosion current over the uncoated samples, a one order of magnitude lowering of Isbcorr over the second type of chromate coating and a one order of magnitude higher Isbcorr over the first type of chromate coating. Impedance results show a two order of magnitude higher impedance at low frequencies over the uncoated and equivalent performance for both types of chromate coatings. EIS and cyclic polarization tests of the conductive state (green colored) versus a non-conductive state (blue colored) of the polymer coating shows that the electrically conductive state is more effective than the insulating state for corrosion protection. This data indicates that the electro-active nature of the polymer coating plays a role in the protection of the alloys. After two months exposure in a.5N NaCl solution, there is no evidence of pitting at the alloy surface for the polymer coated samples under scanning electron microscopy (SEM) images, indicating a change in the typical corrosion mechanism for aluminum alloys. The

  2. Spectroscopic analysis of element concentrations in aluminum alloy using nanosecond laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Luo, Wenfeng; Tang, Jie; Gao, Cunxiao; Wang, Haojing; Zhao, Wei

    2010-06-01

    A plasma generated by 1064 nm Nd:YAG laser irradiation of aluminum alloy in air at atmospheric pressure was studied spectroscopically. The electron density was inferred by measuring the Stark broadened line profile of Cu(I) 324.75 nm, while the electron temperature was determined using the Boltzmann plot method with ten neutral iron lines. Based on the results, local thermodynamic equilibrium was studied. Moreover, calibration curves were presented for samples containing Si, Fe, Cu, Mn, Mg, Ni, Zn and Ti, and the limit of detection of trace elements was calculated based on experimental results.

  3. Selection Of Cutting Inserts For Aluminum Alloys Machining By Using MCDM Method

    NASA Astrophysics Data System (ADS)

    Madić, Miloš; Radovanović, Miroslav; Petković, Dušan; Nedić, Bogdan

    2015-07-01

    Machining of aluminum and its alloys requires the use of cutting tools with special geometry and material. Since there exists a number of cutting tools for aluminum machining, each with unique characteristics, selection of the most appropriate cutting tool for a given application is very complex task which can be viewed as a multi-criteria decision making (MCDM) problem. This paper is focused on multi-criteria analysis of VCGT cutting inserts for aluminum alloys turning by applying recently developed MCDM method, i.e. weighted aggregated sum product assessment (WASPAS) method. The MCDM model was defined using the available catalogue data from cutting tool manufacturers.

  4. Exfoliation Corrosion Behavior of 2B06 Aluminum Alloy in a Tropical Marine Atmosphere

    NASA Astrophysics Data System (ADS)

    Cui, Z. Y.; Li, X. G.; Xiao, K.; Dong, C. F.; Wang, L. W.; Zhang, D. W.; Liu, Z. Y.

    2015-01-01

    In this study, corrosion behavior of 2B06 aluminum alloy was investigated after exposure to a tropical marine atmosphere for up to 4 years. After 6 months, the specimen showed exfoliation corrosion as well as rapid increase in thickness loss and corrosion rate. Exfoliation corrosion was found to initiate from hydrogen-assisted intergranular cracks and propagate extensively due to the wedge effect of the corrosion products. During the exposure test, corrosion on the groundward surface was considerably more severe than that on the skyward surface, which could be attributed to the different exposure conditions on the two surfaces.

  5. Evolution of microstructure and precipitates in 2xxx aluminum alloy after severe plastic deformation

    NASA Astrophysics Data System (ADS)

    Adamczyk-Cieslak, B.; Zdunek, J.; Mizera, J.

    2016-04-01

    This paper investigates the influence of precipitation on the microstructure development in a 2xxx aluminum alloy subjected to hydrostatic extrusion. A three step reduction of the diameter was performed using hydrostatic extrusion (HE) process: from 20mm (initial state) to 10 mm, 5 mm and 3 mm, which corresponds to the logarithmic deformations ɛ = 1.4, ɛ = 2.8 and ɛ = 3.8 respectively. The microstructure and precipitation analysis before and after deformation was performed using transmission electron microscope (TEM), and scanning electron microscopy (SEM). As a result of the tests, a very significant influence of precipitation on the degree of refinement and mechanism of microstructure transformation was stated.

  6. Radiographic detection of defects in friction stir welding on aluminum alloy AMg5M

    SciTech Connect

    Tarasov, Sergei Yu. Kolubaev, Evgeny A.; Rubtsov, Valery E.

    2014-11-14

    In order to reveal weld defects specific to friction stir welding we undertook radiographic inspection of AMg5M aluminum alloy welded joints. Weld defects in the form of voids have been revealed in the weld obtained under the non-optimal rotation and feed rate. Both shape and size of these defects have been confirmed by examining metallographically successive sections prepared in the weld plane as well as in the plane transversal to the tool feed direction. Linear defects have been also found in the sections that are not seen in the radiographic images. Both the preferable localization and origination of the defects have been analyzed.

  7. The NBS: Processing/Microstructure/Property Relationships in 2024 Aluminum Alloy Plates

    NASA Technical Reports Server (NTRS)

    Ives, L. K.; Swartzendruber, W. J.; Boettinger, W. J.; Rosen, M.; Ridder, S. D.

    1983-01-01

    As received plates of 2024 aluminum alloy were examined. Topics covered include: solidification segregation studies; microsegregation and macrosegregation in laboratory and commercially cast ingots; C-curves and nondestructive evaluation; time-temperature precipitation diagrams and the relationships between mechanical properties and NDE measurements; transmission electron microscopy studies; the relationship between microstructure and properties; ultrasonic characterization; eddy-current conductivity characterization; the study of aging process by means of dynamic eddy current measurements; and Heat flow-property predictions, property degradations due to improve quench from the solution heat treatment temperature.

  8. Through-the-thickness fatigue crack closure behavior in an aluminum alloy

    NASA Technical Reports Server (NTRS)

    Dawicke, D. S.; Newman, J. C., Jr.; Grandt, A. F., Jr.

    1990-01-01

    The variation in fatigue crack closure behavior across the thickness of aluminum alloy specimens was investigated. The specimen geometries examined were the middle crack tension M(T) and compact tension C(T). The fatigue crack closure behavior was determined using remote displacement and strain gages, near tip strain gages, and fatigue striations. A hybrid experimental/numerical method was also used to infer the crack opening loads. The results indicate a variation in crack opening load, of 0.2 in the specimen interior to 0.4 to 0.5 at the surface.

  9. Aerospace Patented High-Strength Aluminum Alloy Used in Commercial Industries

    NASA Technical Reports Server (NTRS)

    2004-01-01

    NASA structural materials engineer, Jonathan Lee, displays blocks and pistons as examples of some of the uses for NASA's patented high-strength aluminum alloy originally developed at Marshall Space Flight Center in Huntsville, Alabama. NASA desired an alloy for aerospace applications with higher strength and wear-resistance at elevated temperatures. The alloy is a solution to reduce costs of aluminum engine pistons and lower engine emissions for the automobile industry. The Boats and Outboard Engines Division at Bombardier Recreational Products of Sturtevant, Wisconsin is using the alloy for pistons in its Evinrude E-Tec outboard engine line.

  10. Structure of the aluminum alloy Al-Cu-Mg cryorolled to different strains

    NASA Astrophysics Data System (ADS)

    Krymskiy, S. V.; Avtokratova, E. V.; Sitdikov, O. Sh.; Mikhaylovskaya, A. V.; Markushev, M. V.

    2015-07-01

    Methods of optical metallography, X-ray diffraction, and transmission and scanning electron microscopy were used to study changes in the structure of the aluminum alloy D16 (2024) caused by isothermal rolling at a temperature of liquid nitrogen. It has been established that the basic structural changes that take place in the material upon deformations to e ˜ 2.0 are due to the formation and evolution of the dislocation structure, which contains cells of nanometer size. With further straining to e ˜ 3.5, the processes of recovery and recrystallization become activated, which lead to the formation of a mixed grain-subgrain nanosized structure.

  11. Morphology of an aluminum alloy eroded by a jet of angular particles impinging at normal incidence

    NASA Technical Reports Server (NTRS)

    Rao, P. V.; Young, S. G.; Buckley, D. H.

    1983-01-01

    The erosion of an aluminum alloy impinged by crushed glass particles at normal incidence was studied. The erosion patterns were analyzed by scanning electron microscopy, energy dispersive X-ray spectroscopy, and surface profilometer measurements. From the analysis of specimens tested at various driving gas pressures and time intervals, four distinct erosion regions were identified. A study of pit morphology and its relationship to cumulative erosion was made. Cutting wear is believed to be the predominant material removal mechanism; some evidence of deformation wear was found during the incubation period.

  12. Crack Initiation from Corrosion Pit in Three Aluminum Alloys Under Ambient and Saltwater Environments

    NASA Astrophysics Data System (ADS)

    Sabelkin, V.; Misak, H. E.; Perel, V. Y.; Mall, S.

    2016-04-01

    Corrosion-pit-to-crack transition behaviors of three aluminum alloys using two pit configurations were investigated under ambient and saltwater environments. Fatigue stress ranges for crack initiation from a through-pit were less than that from a corner-pit in both environments in all three materials, while stress intensity factor ranges showed the opposite trend. Further, stress ranges or stress intensity factor ranges for crack initiation were less in saltwater than that in ambient environment for both pit configurations. Fatigue damage mechanisms in a test environment were similar for both pit configurations in all three materials. An empirical relationship is proposed to estimate pit-to-crack transition fatigue cycles.

  13. Characterization of large 2219 aluminum alloy hand forgings for the space shuttle solid rocket booster

    NASA Technical Reports Server (NTRS)

    Brennecke, M. W.

    1978-01-01

    The mechanical properties, including fracture toughness, and stress corrosion properties of four types of 2219-T852 aluminum alloy hand forgings are presented. Weight of the forgings varied between 450 and 3500 lb at the time of heat treatment and dimensions exceeded the maximum covered in existing specifications. The forgings were destructively tested to develop reliable mechanical property data to replace estimates employed in the design of the Space Shuttle Solid Rocket Booster (SRB) and to establish minimum guaranteed properties for structural refinement and for entry into specification revisions. The report summarizes data required from the forgers and from the SRB Structures contractor.

  14. Stress corrosion evaluation of powder metallurgy aluminum alloy 7091 with the breaking load test method

    NASA Technical Reports Server (NTRS)

    Domack, Marcia S.

    1987-01-01

    The stress corrosion behavior of the P/M aluminum alloy 7091 is evaluated in two overaged heat treatment conditions, T7E69 and T7E70, using an accelerated test technique known as the breaking load test method. The breaking load data obtained in this study indicate that P/M 7091 alloy is highly resistant to stress corrosion in both longitudinal and transverse orientations at stress levels up to 90 percent of the material yield strength. The reduction in mean breaking stress as a result of corrosive attack is smallest for the more overaged T7E70 condition. Details of the test procedure are included.

  15. Casting defects in low-pressure die-cast aluminum alloy wheels

    NASA Astrophysics Data System (ADS)

    Zhang, B.; Cockcroft, S. L.; Maijer, D. M.; Zhu, J. D.; Phillion, A. B.

    2005-11-01

    Defects in automotive aluminum alloy casting continue to challenge metallurgists and production engineers as greater emphasis is placed on product quality and production cost. A range of casting-related defects found in low-pressure die-cast aluminum wheels were examined metallographically in samples taken from several industrial wheel-casting facilities. The defects examined include macro- and micro- porosity, entrained oxide films, and exogenous oxide inclusions. Particular emphasis is placed on the impact of these defects with respect to the three main casting-related criteria by which automotive wheel quality are judged: wheel cosmetics, air-tightness, and wheel mechanical performance.

  16. Ultrasonic fatigue of E319 cast aluminum alloy in the long lifetime regime

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoxia

    2007-12-01

    The fatigue behavior of an E319 cast aluminum alloy used in the production of automotive cylinder heads, was studied by using both ultrasonic and conventional fatigue techniques in order to understand the potential effect of frequency on fatigue behavior of cast aluminum alloys. The effect of frequency, environment and temperature on S-N behavior, fatigue crack initiation and propagation behavior of E319 cast aluminum alloy was investigated. It was observed that, at room temperature, in the lifetime regime of less than 107 cycles, fatigue lives at 20 kHz are approximately five to ten times longer than fatigue lives at 75 Hz; while at 107 cycles, the effect of frequency is substantially reduced. At elevated temperature (150 and 250°C), however, the difference in fatigue lives between 20 kHz and 75 Hz persists over the entire range of stress examined. The effect of frequency on fatigue resistance is attributable to an environmental effect on fatigue crack growth rate at all temperatures. For E319 cast aluminum alloy, fatigue crack growth rates increase with increasing water exposure, P/f, which can be estimated by a modified superposition model. Fatigue resistance decreased with increasing temperature and the temperature dependence of fatigue strength at 108 cycles follows closely the temperature dependence of yield and tensile strength. The effect of temperature on fatigue resistance primarily results from the intrinsic effect of temperature on Young's modulus and yield strength. The environmental contribution to fatigue crack growth rates modestly decreases with increasing temperature. At room temperature, an endurance limit is demonstrated in the lifetime regime beyond 107 cycles and the fatigue strength at 10 8 cycles was investigated using the ultrasonic fatigue technique. The fatigue strength is correlated with both size and location of the initiating pores through a threshold stress intensity factor for fatigue crack growth. A probabilistic model was

  17. Acoustic emission features at deformation of aluminum alloys with different strain behavior types

    NASA Astrophysics Data System (ADS)

    Bashkov, O. V.; Panin, S. V.; Bashkova, T. I.; Byakov, A. V.; Popkova, A. A.; Shakirov, I. V.

    2015-10-01

    The analysis of the deformation and fracture peculiarities of two kinds of aluminum alloys with different deformation behavior types using AE method was carried out. It is shown that an effective description of deformation mechanisms with the use of AE method can be made by sorting and identification of AE signal sources. Strain stages identified through the strain hardening diagrams are consistent with AE activity graphs for different types of AE sources at these stages. AE activity at the stage of strain hardening substantially depends on heterogeneous structure characteristics of materials under loading.

  18. Ultrasonic-assisted friction stir welding on V95AT1 (7075) aluminum alloy

    NASA Astrophysics Data System (ADS)

    Tarasov, S. Yu.; Rubtsov, V. Ye.; Kolubaev, E. A.; Ivanov, A. N.; Fortuna, S. V.; Eliseev, A. A.

    2015-10-01

    Ultrasonic-assisted friction stir butt welding on aluminum alloy V95AT1 (7075) has been carried out. Samples have been characterized using metallography, microhardness and XRD. As shown, ultrasonic treatment during welding provides extra plasticizing of metal and better stirring efficiency. The latter serves for elimination of defects, such as root flaw and grain refining in the stir zone. The stress state in the welded joint is characterized by tensile stress in the direction of the weld seam centerline and compression in the transversal direction. The ultrasonic treatment was shown to increase the compression stress and relieve the tensile one.

  19. Influences of post-weld heat treatment on tensile properties of friction stir-welded AA6061 aluminum alloy joints

    SciTech Connect

    Elangovan, K.; Balasubramanian, V.

    2008-09-15

    This paper reports on studies of the influences of various post-weld heat treatment procedures on tensile properties of friction stir-welded AA6061 aluminum alloy joints. Rolled plates of 6-mm thick AA6061 aluminum alloy were used to fabricate the joints. Solution treatment, an artificial aging treatment and a combination of both were given to the welded joints. Tensile properties such as yield strength, tensile strength, elongation and joint efficiency were evaluated. Microstructures of the welded joints were analyzed using optical microscopy and transmission electron microscopy. A simple artificial aging treatment was found to be more beneficial than other treatment methods to enhance the tensile properties of the friction stir-welded AA6061 aluminum alloy joints.

  20. Fabrication of the micro/nano-structure superhydrophobic surface on aluminum alloy by sulfuric acid anodizing and polypropylene coating.

    PubMed

    Wu, Ruomei; Liang, Shuquan; Liu, Jun; Pan, Anqiang; Yu, Y; Tang, Yan

    2013-03-01

    The preparation of the superhydrophobic surface on aluminum alloy by anodizing and polypropylene (PP) coating was reported. Both the different anodizing process and different PP coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. By PP coating after anodizing, a good superhydrophobic surface was facilely fabricated. The optimum conditions for anodizing were determined by orthogonal experiments. After the aluminium-alloy was grinded with 600# sandpaper, pretreated by 73 g/L hydrochloric acid solution at 1 min, when the concentration of sulfuric acid was 180 g/L, the concentration of oxalic acid was 5 g/L, the concentration of potassium dichromate was 10 g/L, the concentration of chloride sodium was 50 g/L and 63 g/L of glycerol, anodization time was 20 min, and anodization current was 1.2 A/dm2, anodization temperature was 30-35 degrees C, the best micro-nanostructure aluminum alloy films was obtained. On the other hand, the PP with different concentrations was used to the PP with different concentrations was used to coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was achieved by coating PP, and the duration of the superhydrophobic surface was improved by modifying the coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was surface with high concentration PP. The morphologies of micro/nano-structure superhydrophobic surface were further confirmed by scanning electron microscope (SEM). The material of PP with the low surface free energy combined with the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface. PMID:23755692

  1. Underwater Shock Response of Air-Backed Thin Aluminum Alloy Plates: An Experimental and Numerical Study

    NASA Astrophysics Data System (ADS)

    Ren, Peng; Zhang, Wei

    2013-06-01

    Studies on dynamic response of structures subjected to underwater explosion shock loading are of interest to ship designers. Understanding the deformation and failure mechanism of simple structures plays an important role in designing of a reliable structure under this kind of loading. The objective of this combined experimental and numerical study is to analyze the deformation and failure characteristics of 5A06 aluminum alloy plates under underwater shock loading. Some non-explosive underwater blast loading experiments were carried out on air backed circular plates of 2 mm thickness. The deformation history of the clamped circular plate was recorded using a high speed camera and the deflections of specimens at different radii were measured in order to identify deformation and failure modes. In the finite element simulations, the strength model of 5A06 aluminum alloy is considered using the slightly modified Johnson-cook mode to describe structure deformation. Good agreement between the numerical simulations and the experimental results is found. Detailed computational results of each scenario are offered to understand the deformation and failure mechanism. National Natural Science Foundation of China (NO.:11072072).

  2. Underwater shock response of air-backed thin aluminum alloy plates: An experimental and numerical study

    NASA Astrophysics Data System (ADS)

    Ren, Peng; Zhang, Wei

    2014-05-01

    Studies on dynamic response of structures subjected to underwater explosion shock loading are of interest to ship designers. Understanding the deformation and failure mechanism of simple structures plays an important role in designing of a reliable structure under this kind of loading. The objective of this combined experimental and numerical study is to analyze the deformation and failure characteristics of 5A06 aluminum alloy plates under underwater shock loading. Some non-explosive underwater blast loading experiments were carried out on air backed circular plates of 2 mm thickness. The deformation history of the clamped circular plate was recorded using a high speed camera and the deflections of specimens at different radii were measured in order to identify deformation and failure modes. In the finite element simulations, the strength model of 5A06 aluminum alloy is considered using the slightly modified Johnson-cook mode to describe structure deformation. Good agreement between the numerical simulations and the experimental results is found. Detailed computational results of each scenario are offered to understand the deformation and failure mechanism.

  3. A Characterization for the Hot Flow Behaviors of As-extruded 7050 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Quan, Guo-zheng; Liu, Jin; Mao, An; Liu, Bo; Zhang, Jin-sheng

    2015-11-01

    The deep understanding of flow behaviors of as-extruded 7050 aluminum alloy significantly contributes to the accuracy simulation for its various plastic forming processes. In order to obtain the improved Arrhenius-type equation with variable parameters for this alloy, a series of compression tests were performed at temperatures of 573 K, 623 K, 673 K, 723 K and strain rates of 0.01 s-1, 0.1 s-1, 1 s-1, 10 s-1 with a height reduction of 60% on Gleeble-1500 thermo-mechanical simulator. It is obvious that strain rate, strain and temperature all have a significant effect on the hot flow behaviors, and the true stress-true strain curves indicate three types after the peak value: decreasing gradually to a steady state with sustaining DRX softening till a balance with work hardening, decreasing continuously with sustaining increasing DRX softening beyond work hardening and maintaining higher stress level after the peak value with a balance between work hardening and DRV softening. Based on the experimental data, the improved Arrhenius-type constitutive model was established to predict the high temperature flow stress of as-extruded 7050 aluminum alloy. The accuracy and reliability of the improved Arrhenius-type model were further evaluated in terms of the correlation coefficient (R), here 0.98428, the average absolute relative error (AARE), here 3.5%. The results indicate that the improved Arrhenius-type constitutive model presents a good predictable ability.

  4. Manufacturing of an aluminum alloy mold for micro-hot embossing of polymeric micro-devices

    NASA Astrophysics Data System (ADS)

    Tran, N. K.; Lam, Y. C.; Yue, C. Y.; Tan, M. J.

    2010-05-01

    In micro-hot embossing of polymeric micro-devices, e.g. microfluidic devices, the quality of the mold plays an important role in determining not only the product quality but also the overall production cost. Often the mold is made of silicon, which is brittle and fails after producing a limited number of parts. Metallic molds produced by micro-machining have a much longer life; however, the surface finish of the mold is not ideal for producing polymeric devices that require good surface finish. The metallic glass mold produced by micro-hot embossing with a silicon master is a recent development, which could produce high quality and high strength molds with long life span. However, metallic glasses are rather costly. In an attempt to reduce the production cost of the mold with acceptable quality, strength and life span, we explore here the manufacture of an aluminum alloy (AA6061-T6) mold by hot embossing using a silicon master. Using a set of channels to be produced on the aluminum alloy as the benchmark, we examine the orientation effect of the channels on the AA6061-T6 mold produced by hot embossing. Finally, to examine the effectiveness of the AA6061-T6 mold, it is employed for the hot embossing of polymeric (TOPAS 8007) substrates.

  5. A Modified Constitutive Equation for Aluminum Alloy Reinforced by Silicon Carbide Particles at Elevated Temperature

    NASA Astrophysics Data System (ADS)

    Yang, Yajing; Li, Fuguo; Yuan, Zhanwei; Qiao, Huijuan

    2013-09-01

    In this paper, the constitutive relationship of an aluminum alloy reinforced by silicon carbide particles is investigated using a new method of double multivariate nonlinear regression (DMNR) in which the strain, strain rate, deformation temperature, and the interaction effect among the strain, strain rate, and deformation temperature are considered. The experimental true stress-strain data were obtained by isothermal hot compression tests on a Gleeble-3500 thermo-mechanical simulator in the temperature range of 623-773 K and the strain rate range of 0.001-10 s-1. The experiments showed that the material-softening behavior changed with the strain rate, and it changed from dynamic recovery to dynamic recrystallization with an increase in the strain rate. A new constitutive equation has been established by the DMNR; the correlation coefficient ( R) and average absolute relative error (AARE) of this model are 0.98 and 7.8%, respectively. To improve the accuracy of the model, separate constitutive relationships were obtained according to the softening behavior. At strain rates of 0.001, 0.01, 0.1, and 1 s-1, the R and AARE are 0.9865 and 6.0%, respectively; at strain rates of 5 and 10 s-1, the R and AARE are 0.9860 and 3.0%, respectively. The DMNR gives an accurate and precise evaluation of the flow stress for the aluminum alloy reinforced by silicon carbide particles.

  6. Ultrasonic irradiation and its application for improving the corrosion resistance of phosphate coatings on aluminum alloys.

    PubMed

    Sheng, Minqi; Wang, Chao; Zhong, Qingdong; Wei, Yinyin; Wang, Yi

    2010-01-01

    In this paper, ultrasonic irradiation was utilized for improving the corrosion resistance of phosphate coatings on aluminum alloys. The chemical composition and morphology of the coatings were analyzed by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The effect of ultrasonic irradiation on the corrosion resistance of phosphate coatings was investigated by polarization curves and electrochemical impedance spectroscopy (EIS). Various effects of the addition of Nd(2)O(3) in phosphating bath on the performance of the coatings were also investigated. Results show that the composition of phosphate coating were Zn(3)(PO(4))(2).4H(2)O(hopeite) and Zn crystals. The phosphate coatings became denser with fewer microscopic holes by utilizing ultrasonic irradiation treatment. The addition of Nd(2)O(3) reduced the crystallinity of the coatings, with the additional result that the crystallites were increasingly nubby and spherical. The corrosion resistance of the coatings was also significantly improved by ultrasonic irradiation treatment; both the anodic and cathodic processes of corrosion taking place on the aluminum alloy substrate were suppressed consequently. In addition, the electrochemical impedance of the coatings was also increased by utilizing ultrasonic irradiation treatment compared with traditional treatment. PMID:19692286

  7. Springback compensation algorithm for tool design in creep age forming of large aluminum alloy plate

    NASA Astrophysics Data System (ADS)

    Xu, Xiaolong; Zhan, Lihua; Huang, Minghui

    2013-12-01

    The creep unified constitutive equations, which was built based on the age forming mechanism of aluminum alloy, was integrated with the commercial finite element analysis software MSC.MARC via the user defined subroutine, CREEP, and the creep age forming process simulations for7055 aluminum alloy plate parts were conducted. Then the springback of the workpiece after forming was calculated by ATOS Professional Software. Based on the combination between simulation results and calculation of springback by ATOS for the formed plate, a new weighted springback compensation algorithm for tool surface modification was developed. The compensate effects between the new algorithm and other overall compensation algorithms on the tool surface are compared. The results show that, the maximal forming error of the workpiece was reduced to below 0.2mm after 5 times compensations with the new weighted algorithm, while error rebound phenomenon occurred and the maximal forming error cannot be reduced to 0.3mm even after 6 times compensations with fixed or variable compensation coefficient, which are based on the overall compensation algorithm.

  8. Butt Welding Joint of Aluminum Alloy by Space GHTA Welding Process in Vacuum

    NASA Astrophysics Data System (ADS)

    Suita, Yoshikazu; Shinike, Shuhei; Ekuni, Tomohide; Terajima, Noboru; Tsukuda, Yoshiyuki; Imagawa, Kichiro

    Aluminum alloys have been used widely in constructing various space structures including the International Space Station (ISS) and launch vehicles. For space applications, welding experiments on aluminum alloy were performed using the GHTA (Gas Hollow Tungsten Arc) welding process using a filler wire feeder in a vacuum. We investigated the melting phenomenon of the base metal and filler wire, bead formation, and the effects of wire feed speed on melting characteristics. The melting mechanism in the base metal during the bead on a plate with wire feed was similar to that for the melt run without wire feed. We clarified the effects of wire feed speed on bead sizes and configurations. Furthermore, the butt welded joint welded using the optimum wire feed speed, and the joint tensile strengths were evaluated. The tensile strength of the square butt joint welded by the pulsed DC GHTA welding with wire feed in a vacuum is nearly equal to that of the same joint welded by conventional GTA (Gas Tungsten Arc) welding in air.

  9. Microstructure, Macrosegregation, and Thermal Analysis of Direct Chill Cast AA5182 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Jamaly, N.; Haghdadi, N.; Phillion, A. B.

    2015-05-01

    The variation in microstructure, macrosegregation, and solidification behavior during aluminum alloy Direct Chill casting is investigated with respect to geometry. Optical microscopy, energy-dispersive analysis, and differential scanning calorimetry were employed to study the grain size evolution, distribution of alloying elements, and solidification sequence across the cross section of DC cast AA5182 aluminum alloy. The results show that (1) grain size increases from the surface to center of the ingot, corresponding to a decrease in the heat extraction rate; (2) there is a considerable macrosegregation of Mg, Mn, and Cr, with Mg showing negative segregation at the center and positive segregation at the surface, Mn showing negative segregation both at center and surface and positive segregation elsewhere, and Cr showing positive segregation at the center and negative segregation at the surface; (3) the solidus and the reaction temperatures vary as a function of position due to the local chemical composition and cooling rate. These findings, which show the interconnectivity of grain size, segregation, and solidification sequence, are useful in further analysis of the DC casting process and in predicting casting-related defects, specifically hot tear formation.

  10. Hazard of ultraviolet radiation emitted in gas tungsten arc welding of aluminum alloys.

    PubMed

    Nakashima, Hitoshi; Utsunomiya, Akihiro; Fujii, Nobuyuki; Okuno, Tsutomu

    2016-01-01

    Ultraviolet radiation (UVR) emitted during arc welding frequently causes keratoconjunctivitis and erythema. The extent of the hazard of UVR varies depending on the welding method and conditions. Therefore, it is important to identify the levels of UVR that are present under various conditions. In this study, we experimentally evaluated the hazard of UVR emitted in gas tungsten arc welding (GTAW) of aluminum alloys. The degree of hazard of UVR is measured by the effective irradiance defined in the American Conference of Governmental Industrial Hygienists guidelines. The effective irradiances measured in this study are in the range 0.10-0.91 mW/cm(2) at a distance of 500 mm from the welding arc. The maximum allowable exposure times corresponding to these levels are only 3.3-33 s/day. This demonstrates that unprotected exposure to UVR emitted by GTAW of aluminum alloys is quite hazardous in practice. In addition, we found the following properties of the hazard of UVR. (1) It is more hazardous at higher welding currents than at lower welding currents. (2) It is more hazardous when magnesium is included in the welding materials than when it is not. (3) The hazard depends on the direction of emission from the arc. PMID:26632121

  11. Microstructure and Properties of Lap Joint Between Aluminum Alloy and Galvanized Steel by CMT

    NASA Astrophysics Data System (ADS)

    Niu, Song; Chen, Su; Dong, Honggang; Zhao, Dongsheng; Zhang, Xiaosheng; Guo, Xin; Wang, Guoqiang

    2016-05-01

    Lap joining of 1-mm-thick Novelist AC 170 PX aluminum alloy to 1.2-mm-thick ST06 Z galvanized steel sheets for automotive applications was conducted by cold metal transfer advanced welding process with ER4043 and ER4047 filler wires. Under the optimized welding parameters with ER4043 filler wire, the tensile shear strength of joint was 189 MPa, reaching 89% of the aluminum alloy base metal. Microstructure and elemental distribution were characterized by optical metalloscope and electron probe microanalysis. The lap joints with ER4043 filler wire had smaller wetting angle and longer bonded line length with better wettability than with ER4047 filler wire during welding with same parameters. The needle-like Al-Fe-Si intermetallic compounds (IMCs) were spalled into the weld and brought negative effect to the tensile strength of joints. With increasing welding current, the needle-like IMCs grew longer and spread further into the weld, which would deteriorate the tensile shear strength.

  12. Simulation to the Cyclic Deformation of Polycrystalline Aluminum Alloy Using Crystal Plasticity Finite Element Method

    NASA Astrophysics Data System (ADS)

    Luo, Juan; Kang, Guozheng; Shi, Mingxing

    2013-01-01

    A crystal plasticity based finite element model (i.e., FE model) is used in this paper to simulate the cyclic deformation of polycrystalline aluminum alloy plates. The Armstrong-Frederick nonlinear kinematic hardening rule is employed in the single crystal constitutive model to capture the Bauschinger effect and ratcheting of aluminum single crystal presented under the cyclic loading conditions. A simple model of latent hardening is used to consider the interaction of dislocations between different slipping systems. The proposed single crystal constitutive model is implemented numerically into a FE code, i.e., ABAQUS. Then, the proposed model is verified by comparing the simulated results of cyclic deformation with the corresponding experimental ones of a face-centered cubic polycrystalline metal, i.e., rolled 5083 aluminum alloy. In the meantime, it is shown that the model is capable of predicting local heterogeneous deformation in single crystal scale, which plays an important role in the macroscopic deformation of polycrystalline aggregates. Under the cyclic loading conditions, the effect of applied strain amplitude on the responded stress amplitude and the dependence of ratcheting strain on the applied stress level are reproduced reasonably.

  13. Creep crack growth behavior of aluminum alloy 2519. Part 1: Experimental analysis

    SciTech Connect

    Hamilton, B.C.; Saxena, A.; McDowell, D.L.; Hall, D.E.

    1997-12-31

    The discipline of time-dependent fracture mechanics has traditionally focused on the creep crack growth behavior of high-temperature materials that display creep-ductile behavior, such as stainless steels and chromium-molybdenum steels. Elevated temperature aluminum alloys, however, have been developed that exhibit creep-brittle behavior; in this case, the creep crack growth rate correlates with the stress intensity factor, K. The fracture characteristics of aluminum alloy 2519-T87 were studied at 135 C, and the creep and creep crack growth behavior were characterized utilizing experimental and numerical methods. The strain to failure for creep deformation specimens was limited to only 1.2 to 2.0%. Creep crack growth tests revealed a unique correlation between the creep crack growth rate and K, a result consistent with creep-brittle behavior. No experimental correlation was found between the creep crack growth rate and the C{sub t} parameter. Microscopy of fracture surfaces revealed distinct regions of intergranular and transgranular fracture, and the transition between the fracture regions was found to occur at a critical K-level. Experimental results also appeared to show that initiation of crack growth (incubation) is controlled by the accumulation of a critical amount of damage ahead of the crack tip and that a correlation exists between the incubation time and K. Total time to failure is viewed as a summation of the incubation period and the crack growth period, and the design importance of incubation time is discussed.

  14. Electrochemical characterization of plasma polymer coatings in corrosion protection of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Chan, Yenfong; Yu, Qingsong

    2005-07-01

    Low-temperature plasma polymerization is a promising pretreatment technique to create environmentally friendly coating systems for corrosion protection of aluminum alloys. In this study, the pretreatment effects of plasma treatment and plasma polymerization on corrosion properties of alclad aluminum alloy 2024-T3 ([2A]) were investigated using electrochemical characterization techniques, including cyclic polarization (CP) and electrochemical impedance spectroscopy (EIS). The [2A] panels were coated with an ultrathin layer (~50 nm) of plasma polymers in a direct current (dc) glow discharge of trimethylsilane or its mixtures with one of two diatomic gases (O2 and N2). The CP measurement results showed that the plasma polymer coated [2A] panels exhibited more negative corrosion potentials (Ecorr), smaller corrosion currents (Icorr), and no surface passivation when compared with uncoated [2A] control panels. The lower values of Icorr imply a higher corrosion resistance on the plasma polymer coated [2A]. When investigated using EIS, these plasma polymer coated [2A] panels exhibited higher impedance (|Z|) at lower frequency when first immersed in electrolyte solution, yet degraded quickly to a similar level as uncoated controls within 1 day of immersion. These results illustrated that thin plasma polymer films provided a certain but very limited corrosion resistance to [2A] substrate; their dominant role in plasma interface engineered coating systems still relied mostly on their adhesion enhancement at metal/paint interface as observed in our previous studies.

  15. Biomimetic superhydrophobic surface of high adhesion fabricated with micronano binary structure on aluminum alloy.

    PubMed

    Liu, Yan; Liu, Jindan; Li, Shuyi; Liu, Jiaan; Han, Zhiwu; Ren, Luquan

    2013-09-25

    Triggered by the microstructure characteristics of the surfaces of typical plant leaves such as the petals of red roses, a biomimetic superhydrophobic surface with high adhesion is successfully fabricated on aluminum alloy. The essential procedure is that samples were processed by a laser, then immersed and etched in nitric acid and copper nitrate, and finally modified by DTS (CH3(CH2)11Si(OCH3)3). The obtained surfaces exhibit a binary structure consisting of microscale crater-like pits and nanoscale reticula. The superhydrophobicity can be simultaneously affected by the micronano binary structure and chemical composition of the surface. The contact angle of the superhydrophobic surface reaches up to 158.8 ± 2°. Especially, the surface with micronano binary structure is revealed to be an excellent adhesive property with petal-effect. Moreover, the superhydrophobic surfaces show excellent stability in aqueous solution with a large pH range and after being exposed long-term in air. In this way, the multifunctional biomimetic structural surface of the aluminum alloy is fabricated. Furthermore, the preparation technology in this article provides a new route for other metal materials. PMID:24016423

  16. Deformation characteristics during Y-shaped tube hydroforming of 6061 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Chu, Guannan; Li, Feng; Liu, Wenjian

    2011-02-01

    To manufacture lightweight tube components for aerospace oil circuit systems, an experiment was run to investigate the deformation characteristics on Y-shaped tube hydroforming of 6061 aluminum alloy. Both strain state and metallurgical structure indicate that there are four kinds of prevailing defects during Y-shaped tube hydroforming: bursting, lack of cylindricity, wrinkling, and thinning due to the poor plastic property of 6061 aluminum alloy. The danger of bursting prevails at the early stage of the operation as a result of excessively high internal pressure. In contrast, wrinkling prevails after the middle stage of the operation as a result of excessively axial feeding and cannot be eliminated during subsequent deformation. Lack of cylindricity is mainly because of insufficient axial feeding and internal pressure but can be eliminated by increasing internal pressure. Elongation and compression deformations are originated on protrusion and main pipe of Y-shape tube respectively all the way through the bulging process. Consequently, minimum and maximum thicknesses are at the top of protrusion and the bottom of Y-shape tube respectively, which induces a V-shape borderline of thickness distribution. According to the excessive plastic deformation, microstructure evolution is originated. Crystal grain of protrusion is elongated and its grain size is about 150 μm. In contrast, crystal grain of the middle zone of main tube is refined greatly, which grain size is 50 μm, decreased by 75%. These are useful to improve the component.

  17. Hazard of ultraviolet radiation emitted in gas tungsten arc welding of aluminum alloys

    PubMed Central

    NAKASHIMA, Hitoshi; UTSUNOMIYA, Akihiro; FUJII, Nobuyuki; OKUNO, Tsutomu

    2015-01-01

    Ultraviolet radiation (UVR) emitted during arc welding frequently causes keratoconjunctivitis and erythema. The extent of the hazard of UVR varies depending on the welding method and conditions. Therefore, it is important to identify the levels of UVR that are present under various conditions. In this study, we experimentally evaluated the hazard of UVR emitted in gas tungsten arc welding (GTAW) of aluminum alloys. The degree of hazard of UVR is measured by the effective irradiance defined in the American Conference of Governmental Industrial Hygienists guidelines. The effective irradiances measured in this study are in the range 0.10–0.91 mW/cm2 at a distance of 500 mm from the welding arc. The maximum allowable exposure times corresponding to these levels are only 3.3–33 s/day. This demonstrates that unprotected exposure to UVR emitted by GTAW of aluminum alloys is quite hazardous in practice. In addition, we found the following properties of the hazard of UVR. (1) It is more hazardous at higher welding currents than at lower welding currents. (2) It is more hazardous when magnesium is included in the welding materials than when it is not. (3) The hazard depends on the direction of emission from the arc. PMID:26632121

  18. Experimental Study of Stationary Shoulder Friction Stir Welded 7N01-T4 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Ji, S. D.; Meng, X. C.; Li, Z. W.; Ma, L.; Gao, S. S.

    2016-03-01

    Stationary shoulder friction stir welding (SSFSW) was successfully used to weld 7N01-T4 aluminum alloy with the thickness of 4 mm. Effects of welding speed on formations, microstructures, and mechanical properties of SSFSW joint were investigated in detail. Under a constant rotational velocity of 2000 rpm, defect-free joints with smooth surface and small flashes are attained using welding speeds of 20 and 30 mm/min. Macrostructure of nugget zone in cross section presents kettle shape. For 7N01-T4 aluminum alloy with low thermal conductivity, decreasing welding speed is beneficial to surface formation of joint. With the increase of welding speed, mechanical properties of joints firstly increase and then decrease. When the welding speed is 30 mm/min, the tensile strength and elongation of joint reach the maximum values of 379 MPa and 7.9%, equivalent to 84.2 and 52% of base material, respectively. Fracture surface morphology exhibits typical ductile fracture. In addition, the minimum hardness value of joint appears in the heat affected zone.

  19. Microstructure and Properties of Lap Joint Between Aluminum Alloy and Galvanized Steel by CMT

    NASA Astrophysics Data System (ADS)

    Niu, Song; Chen, Su; Dong, Honggang; Zhao, Dongsheng; Zhang, Xiaosheng; Guo, Xin; Wang, Guoqiang

    2016-04-01

    Lap joining of 1-mm-thick Novelist AC 170 PX aluminum alloy to 1.2-mm-thick ST06 Z galvanized steel sheets for automotive applications was conducted by cold metal transfer advanced welding process with ER4043 and ER4047 filler wires. Under the optimized welding parameters with ER4043 filler wire, the tensile shear strength of joint was 189 MPa, reaching 89% of the aluminum alloy base metal. Microstructure and elemental distribution were characterized by optical metalloscope and electron probe microanalysis. The lap joints with ER4043 filler wire had smaller wetting angle and longer bonded line length with better wettability than with ER4047 filler wire during welding with same parameters. The needle-like Al-Fe-Si intermetallic compounds (IMCs) were spalled into the weld and brought negative effect to the tensile strength of joints. With increasing welding current, the needle-like IMCs grew longer and spread further into the weld, which would deteriorate the tensile shear strength.

  20. Hard particle reinforced aluminum-alloys for aircraft applications EWISCO 1993--1994

    SciTech Connect

    Lugscheider, E.; Jokiel, P.; Remer, P.; Yushchenko, K.; Borisov, Y.; Vitiaz, P.; Steinhaeuser, S.

    1994-12-31

    Light metals such as aluminum, titanium, magnesium are widely used as structural materials in industrial parts. Their low density combined with reasonable physical properties are the main advantages of these materials that have led to a wide range of applications in transportation, particularly in the fabrication of aircrafts. Some of the disadvantages of these light metals and alloys are low wear resistance, high reactivity and low thermal tolerance. Thermal sprayed coatings are required to protect these structures and to broaden the use of these materials. The goal of this collaborative research work was to improve wear and corrosion properties of common Al-alloys. Five hard particle reinforced aluminum based powders were sprayed with different thermal spray processes. In order to optimize the wear and corrosion resistance of the coatings different spray processes and spray parameters were investigated. The coatings were produced mainly using atmospherical plasma spraying and CDS (continuous detonation spraying). Further tests with two ukrainian types of flame spraying were carried out. The aluminum alloy 7075 [AlZnMgCu1,5] was used as substrate material. Powder and coating morphology, porosity and homogeneity were investigated. Several tests for wear, corrosion behavior, bond strength and hardness were also carried out. The results of this investigation illustrate the excellent properties of thermal sprayed surface coatings in the field of wear and corrosion protection which expands the future applications of these aluminum alloys. This paper presents the results obtained at the Materials Science Institute, Aachen.

  1. Characteristics of the aluminum alloy sheets for forming and application examples

    NASA Astrophysics Data System (ADS)

    Uema, Naoyuki; Asano, Mineo

    2013-12-01

    In this paper, the characteristics and application examples of aluminum alloy sheets developed for automotive parts by Sumitomo Light Metal are described. For the automotive closure panels (ex., hood, back-door), an Al-Mg-Si alloy sheet having an excellent hemming performance was developed. The cause of the occurrence and the propagation of cracks by bending were considered to be the combined effect of the shear bands formed across several crystal grains and the micro-voids formed around the second phase particles. By reducing the shear band formation during bending by controlling the crystallographic texture, the Al-Mg-Si alloy sheets showed an excellent hemming performance. For the automotive outer panels (ex., roof, fender, trunk-lid), an Al-Mg alloy sheet, which has both a good hot blow formability and excellent surface appearance after hot blow forming was developed, and hot blow forming technology was put to practical use using this developed Al-Mg alloy sheet. For automotive heat insulators, a high ductile Al-Fe alloy sheet was developed. The heat insulator, which integrated several panels, was put into practical use using this developed Al-Fe alloy sheet. The textured sheet was often used as a heat insulator in order to reduce the thickness of the aluminum alloy sheet and obtain good press formability. The new textured sheet, which has both high rigidity and good press formability for heat insulators, was developed by FE analysis.

  2. System integration and demonstration of adhesive bonded high temperature aluminum alloys for aerospace structure, phase 2

    NASA Technical Reports Server (NTRS)

    Falcone, Anthony; Laakso, John H.

    1993-01-01

    Adhesive bonding materials and processes were evaluated for assembly of future high-temperature aluminum alloy structural components such as may be used in high-speed civil transport aircraft and space launch vehicles. A number of candidate high-temperature adhesives were selected and screening tests were conducted using single lap shear specimens. The selected adhesives were then used to bond sandwich (titanium core) test specimens, adhesive toughness test specimens, and isothermally aged lap shear specimens. Moderate-to-high lap shear strengths were obtained from bonded high-temperature aluminum and silicon carbide particulate-reinforced (SiC(sub p)) aluminum specimens. Shear strengths typically exceeded 3500 to 4000 lb/in(sup 2) and flatwise tensile strengths exceeded 750 lb/in(sup 2) even at elevated temperatures (300 F) using a bismaleimide adhesive. All faceskin-to-core bonds displayed excellent tear strength. The existing production phosphoric acid anodize surface preparation process developed at Boeing was used, and gave good performance with all of the aluminum and silicon carbide particulate-reinforced aluminum alloys investigated. The results of this program support using bonded assemblies of high-temperature aluminum components in applications where bonding is often used (e.g., secondary structures and tear stoppers).

  3. Study on Microstructure and Electrochemical Corrosion Behavior of PEO Coatings Formed on Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Xiang, N.; Song, R. G.; Li, H.; Wang, C.; Mao, Q. Z.; Xiong, Y.

    2015-12-01

    Plasma electrolytic oxidation (PEO) treated 6063 aluminum alloy was applied in a silicate- and borate-based alkaline solution. The microstructure and electrochemical corrosion behavior were studied by scanning electron microscopy, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization techniques. The results showed that the silicate-based PEO coating was of a denser structure compared with that of borate-based PEO coating. In addition, the silicate-based PEO coating was composed of more phased (Al9Si) than borate-based PEO coating. The results of corrosion test indicated that the silicate-based PEO coating provided a superior protection to 6063 aluminum alloy substrate, while borate-based PEO coating with a porous structure showed an inferior conservancy against corrosive electrolyte. Furthermore, the EIS tests proved that both coatings were capable to resist the aggressive erosion in 0.5 M NaCl solution after 72 h of immersion. However, the borate-based PEO coating could not provide sufficient protection to the substrate after 72-h immersion in 1 M NaCl solution.

  4. Standard specification for aluminum and aluminum-alloy seamless condenser and heat-exchanger tubes with integral fins. ASTM standard

    SciTech Connect

    1995-07-01

    This specification is under the jurisdiction of ASTM Committee B-7 on Light Metals and Alloys and is the direct responsibility of Subcommittee B07.03 on Aluminum Alloy Wrought Products. Current edition approved May 15, 1995. Published July 1995. Originally published as B 404-63T. Last previous edition B 404-92a.

  5. Effect of Service Stress on Impact Resistance, X-ray Diffraction Patterns, and Microstructure of 25s Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Kies, J A; Quick, G W

    1939-01-01

    Report presents the results of a great number of tests made to determine the effect of service stresses on the impact resistance, the x-ray diffraction patterns, and the microstructure of 25s aluminum alloy. Many of the specimens were taken from actual propeller blades and others were cut from 13/16-inch rod furnished by the Aluminum Company of America.

  6. Synthetic sea water - An improved stress corrosion test medium for aluminum alloys

    NASA Technical Reports Server (NTRS)

    Humphries, T. S.; Nelson, E. E.

    1973-01-01

    A major problem in evaluating the stress corrosion cracking resistance of aluminum alloys by alternate immersion in 3.5 percent salt (NaCl) water is excessive pitting corrosion. Several methods were examined to eliminate this problem and to find an improved accelerated test medium. These included the addition of chromate inhibitors, surface treatment of specimens, and immersion in synthetic sea water. The results indicate that alternate immersion in synthetic sea water is a very promising stress corrosion test medium. Neither chromate inhibitors nor surface treatment (anodize and alodine) of the aluminum specimens improved the performance of alternate immersion in 3.5 percent salt water sufficiently to be classified as an effective stress corrosion test method.

  7. Aerospace Patented High-Strength Aluminum Alloy Used in Commercial Industries

    NASA Technical Reports Server (NTRS)

    2004-01-01

    NASA structural materials engineers at Marshall Space Flight Center (MSFC) in Huntsville, Alabama developed a high-strength aluminum alloy for aerospace applications with higher strength and wear-resistance at elevated temperatures. The alloy is a solution to reduce costs of aluminum engine pistons and lower engine emissions for the automobile industry. The Boats and Outboard Engines Division at Bombardier Recreational Products of Sturtevant, Wisconsin is using the alloy for pistons in its Evinrude E-Tec outboard, 40-90 horsepower, engine line. The alloy pistons make the outboard motor quieter and cleaner, while improving fuel mileage and increasing engine durability. The engines comply with California Air resources Board emissions standards, some of the most stringent in the United States. (photo credit: Bombardiier Recreational Products)

  8. Microstructural and Mechanical Characteristics of Aluminum Alloy AA5754 Friction Stir Spot Welds

    NASA Astrophysics Data System (ADS)

    Mahmoud, T. S.; Khalifa, T. A.

    2014-03-01

    In the present investigation, friction stir spot welding on annealed aluminum alloy AA5754 sheets was performed. The influences of the tool rotational speed and tool stirring (dwell) time on the weld structure and static strength of welds were evaluated. The results revealed that the width of the completely metallurgical-bonded region increases with the increasing tool rotational speed and/or the dwell time up to certain levels. Increasing such parameters beyond these levels slightly reduces the width of the bonding region. The stirred zone exhibited higher microhardness than that of the base material. The tensile-shear force was found to increase with the increasing tool rotational speed and/or dwell time up to a certain level (9s). Higher tool rotational speeds and/or prolonged dwell times slightly reduce(s) the tensile-shear force.

  9. Microstructures and Mechanical Properties of Friction Stir Spot Welded Aluminum Alloy AA2014

    NASA Astrophysics Data System (ADS)

    Babu, S.; Sankar, V. S.; Janaki Ram, G. D.; Venkitakrishnan, P. V.; Madhusudhan Reddy, G.; Prasad Rao, K.

    2013-01-01

    Friction stir spot welding (FSSW) is a relatively recent development, which can provide a superior alternative to resistance spot welding and riveting for fabrication of aluminum sheet metal structures. In the current work, FSSW experiments were conducted in 3-mm thick sheets of aluminum alloy 2014 in T4 and T6 conditions, with and without Alclad layers. The effects of tool geometry and welding process parameters on joint formation were investigated. A good correlation between process parameters, bond width, hook height, joint strength, and fracture mode was observed. The presence of Alclad layers and the base metal temper condition were found to have no major effect on joint formation and joint strength. Friction stir spot welds produced under optimum conditions were found to be superior to riveted joints in lap-shear and cross-tension tests. The prospects of FSSW in aluminum sheet metal fabrication are discussed.

  10. Stress Corrosion Cracking Behavior of Peened Friction Stir Welded 2195 Aluminum Alloy Joints

    NASA Astrophysics Data System (ADS)

    Hatamleh, Omar; Singh, Preet M.; Garmestani, Hamid

    2009-06-01

    The surface treatment techniques of laser and shot peening were used to investigate their effect on stress corrosion cracking (SCC) in friction stir welded (FSW) 2195 aluminum alloy joints. The investigation consisted of two parts: the first part explored the peening effects on slow strain rate testing (SSRT) in a 3.5% NaCl solution, while the second part investigated the effects of peening on corrosion while submerged in a 3.5% NaCl solution with no external loads applied. For the SSRT, the laser-peened samples demonstrated superior properties to the other samples, but no signs of corrosion pitting or SCC were evident on any of the samples. For the second part of the study, the FSW plates were inspected periodically for signs of corrosion. After 60 days there were signs of corrosion pitting, but no stress corrosion cracking was noticed in any of the peened and unpeened samples.

  11. Residual Stresses in Friction-Stir-Welded 2195 and 7075 Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Hatamleh, Omar; Rivero, Iris V.; Maredia, Arif

    2008-12-01

    Surface residual stresses (RSs) were characterized along friction-stir-welded 2195 and 7075 aluminum alloy (AA) plates. The surface measurements were obtained through X-ray diffraction (XRD) at five different locations along the weld. Each location consisted of several regions across the welded plate including the weld nugget, thermomechanically affected zone (TMAZ), heat-affected zone (HAZ), and base material. Measurements revealed that RSs were not uniform along the welded plate, with the highest RSs obtained on the middle of the plate. The RSs across the weld were also asymmetric relative to the weld centerline, with RSs as high as 231 MPa in the TMAZ for the retreating side of the weld.

  12. Surface roughness and friction coefficient in peened friction stir welded 2195 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Hatamleh, Omar; Smith, James; Cohen, Donald; Bradley, Robert

    2009-05-01

    The tribological properties of friction stir welded 2195 aluminum alloy joints were investigated for several laser- and shot-peened specimens. The first portion of this study assessed the surface roughness changes at different regions of the weld resulting from the various peening processes and included an atomic force microscopy (AFM) study to reveal fine structures. The second portion investigated the friction characteristics for various conditions when slid against a 440C ball slider. Shot peening resulted in significant surface roughness when compared to the unpeened and laser-peened samples. The initial friction for all types of specimens was highly variable. However, long-term friction was shown to be lowest for samples with no peening treatment. Laser peening caused the friction to increase slightly. The shot peening process on the other hand resulted in an increase of the long-term friction effects on both sides of the weld.

  13. Compression Behavior and Energy Absorption of Aluminum Alloy AA6061 Tubes with Multiple Holes

    NASA Astrophysics Data System (ADS)

    Simhachalam, Bade; Lakshmana Rao, C.; Srinivas, Krishna

    2014-05-01

    In this article, compression behavior and energy absorption of aluminum alloy AA6061 tubes are investigated both experimentally and numerically. Static and dynamic simulations are done using LS-Dyna Software for AA6061 tubes. True stress-plastic strain curves from the tensile test are used in the static and dynamic simulations of AA6061 tubes. The energy absorption values between experimental compression results and numeral simulation are found to be in good agreement. Dynamic simulations are done with drop velocity of up to 10 m/s to understand the inertia effects on energy absorption. The deformed modes from the numerical simulation are compared between tubes with and without holes in static and dynamic conditions.

  14. Metallurgical characterization of the fracture of several high strength aluminum alloys

    NASA Technical Reports Server (NTRS)

    Bhandarkar, M. D.; Lisagor, W. B.

    1977-01-01

    The fracture behavior for structural aluminum alloys (2024, 6061, 7075, and 7178) was examined in selected heat treatments. The investigation included tensile, shear, and precracked notch-bend specimens fractured at ambient temperature under monotonic loading. Specimens were obtained from thin sheets and thick plates and were tested in longitudinal and transverse orientations at different strain rates. Microstructures of alloys were examined using the optical microscope and the scanning electron microscope with associated energy dispersive X ray chemical analysis. Several different types of second phase particles, some not reported by other investigators, were identified in the alloys. Fracture morphology was related to microstructural variables, test variables, and type of commercial product. Specimen orientation examined in the present investigation had little effect on fracture morphology. Test strain rate changes resulted in some change in shear fracture morphology, but not in fracture morphology of tensile specimens.

  15. Diffusion-controlled wear of steel friction stir welding tools used on aluminum alloys

    NASA Astrophysics Data System (ADS)

    Tarasov, S. Yu.; Kalashnikova, T. A.; Kalashnikov, K. N.; Rubtsov, V. E.; Eliseev, A. A.; Kolubaev, E. A.

    2015-10-01

    The worn surfaces of steel instruments used for friction stir welding on AMg5M aluminum alloy have been examined. An adhesion transfer layer resulted on the steel tool surface from welding the aluminum-magnesium alloy. Diffusion between this layer and steel base metal resulted in formation of an intermetallic Fe-Al layer (IMC). The hardness of the IMC has been measured using a nanohardness tester. It was found that the IMC layers maximum hardness changed from 998 to 1698 HV. The continuous IMC layers may serve as a wear-resistant coating, however, the IMC were also found in the shape of spikes directed into the tool's body, which created conditions for wear particle formation by fracture.

  16. Low temperature deformation behavior of an electromagnetically bulged 5052 aluminum alloy

    PubMed Central

    Li, Zu; Li, Ning; Wang, Duzhen; Ouyang, Di; Liu, Lin

    2016-01-01

    The fundamental understanding of the deformation behavior of electromagnetically formed metallic components under extreme conditions is important. Here, the effect of low temperature on the deformation behavior of an electromagnetically-bulged 5052 aluminum alloy was investigated through uniaxial tension. We found that the Portevin-Le Chatelier Effect, designated by the serrated characteristic in stress-strain curves, continuously decays until completely disappears with decreasing temperature. The physical origin of the phenomenon is rationalized on the basis of the theoretical analysis and the Monte Carlo simulation, which reveal an increasing resistance to dislocation motion imposed by lowering temperature. The dislocations are captured completely by solute atoms at −50 °C, which results in the extinction of Portevin-Le Chatelier. The detailed mechanism responsible for this process is further examined through Monte Carlo simulation. PMID:27426919

  17. A Comparison of Sheet Forming Methods for 5754-O Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Venkatesan, Senthilkumar; Pourboghrat, Farhang; Carsley, John E.

    2011-08-01

    The goal of this research was to verify, through experimentation and numerical modeling, that the sheet hydroforming process is a suitable alternative to conventional forming methods such as stamping for 5754-O aluminum alloy sheets. Numerical analyses included implementation of a temperature-dependent anisotropic yield function (YLD 2000-2d) and corresponding forming limit diagram (FLD) into the commercial FEM code LS-Dyna as a user material subroutine (UMAT). The temperature-dependent material model was used in a coupled thermo-mechanical finite element model to assess the accuracy of the UMAT's ability to predict both forming and failure behavior of AA5754-O under various forming conditions [4]. Numerical investigations proved that counteracting pressure used in sheet hydroforming drastically improves the draw depth, irons out wrinkles and delays the onset of failure when compared to conventional forming processes.

  18. Microstructure, Mechanical Properties, and Texture Evolution of Aluminum Alloy 7005 by Accumulative Roll Bonding

    NASA Astrophysics Data System (ADS)

    Xie, Hu; Wang, M. P.; Chen, Wei; Jia, Yanlin

    2016-03-01

    In the present work, the accumulative roll bonding process was carried out on a 7005 aluminum alloy sheet to six passes. The microstructure and texture evolution was investigated by transmission electron microscope, electron backscatter diffraction analysis, and x-ray texture goniometer. With the increase of ARB passes, the microstructure was refined and the fraction of high angle boundaries increased. The hardness of different ARB process specimens was measured and showed that as the ARB passes increased, the hardness rose obviously. The tensile strength of 6 passes reaches 423.4 MPa and the elongation is 4.6%. The material is strongly textured where individual layers possess typical FCC rolling texture components and the variation of each texture is different. This is attributed to the microstructure evolution during the ARB process.

  19. Effects of Solid-Liquid Mixing on Microstructure of Semi-Solid A356 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Guo, H. M.; Wang, L. J.; Wang, Q.; Yang, X. J.

    2014-08-01

    The desired starting material for semi-solid processing is the semi-solid slurry in which the solid phase is present as fine and globular particles. A modified solid-liquid mixing (SLM) is reported wherein semi-solid slurry can be produced by mixing a solid alloy block into a liquid alloy, and mechanical vibration is utilized to enhance the mixing. Effects such as liquid alloy temperature, mass ratio, and mixing intensity on the microstructure and the cooling curves during SLM were evaluated. 2D and 3D microstructure analysis of treated A356 aluminum alloy shows that microstructure can be refined significantly with a considerable morphology change in primary Al phase. It is critical that the temperature of mixture after mixing is lower than its liquidus temperature to obtain a valid SLM process. Specially, mixing intensity is identified as a primary factor for a favorable microstructure of semi-solid slurry.

  20. A study of spectrum fatigue crack propagation in two aluminum alloys. 2: Influence of microstructures

    NASA Technical Reports Server (NTRS)

    Telesman, J.; Antolovich, S. D.

    1985-01-01

    The important metallurgical factors that influence both constant amplitude and spectrum crack growth behavior in aluminum alloys were investigated. The effect of microstructural features such as grain size, inclusions, and dispersoids was evaluated. It was shown that a lower stress intensities, the I/M 7050 alloy showed better fatigue crack propagation (FCP) resistance than P/M 7091 alloy for both constant amplitude and spectrum testing. It was suggested that the most important microstructural variable accounting for superior FCP resistance of 7050 alloy is its large grain size. It was further postulated that the inhomogenous planar slip and large grain size of 7050 limit dislocation interactions and thus increase slip reversibility which improves FCP performance. The hypothesis was supported by establishing that the cyclic strain hardening exponent for the 7091 alloy is higher than that of 7050.

  1. YIELD STRENGTH PREDICTION FOR RAPID AGE-HARDENING HEAT TREATMENT OF ALUMINUM ALLOYS

    SciTech Connect

    Yin, Hebi; Sabau, Adrian S; Ludtka, Gerard Michael; Skszek, Timothy; Niu, X

    2013-01-01

    A constitutive model has been developed to predict the yield strength aging curves for aluminum casting alloys during non-isothermal age-hardening processes. The model provides the specific relationship between the process variables and yield strength. Several aging heat treatment scenarios have been investigated using the proposed model, including two-step aging recipes. Two-step aging heat treatments involve a low temperature regime to promote nucleation of secondary phases and a second step at higher temperature for the growth of the secondary phases. The predicted results show that yield strength of approximately 300MPa might be obtained in shorter aging time, of approximately 30 minutes. Thus, better mechanical properties can be obtained by optimizing the time-temperature schedules for the precipitation hardening process of heat treatable aluminum alloys.

  2. Modeling of Flow Stress of High Titanium Content 6061 Aluminum Alloy Under Hot Compression

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Guan, Yingping; Wang, Zhenhua

    2016-07-01

    Hot compression tests were performed on high titanium content 6061 aluminum alloy (AA 6061-Ti) using a Gleeble-3500 thermomechanical testing system at temperatures from 350 to 510 °C with a constant strain rate in the range of 0.001-10 s-1. Three types of flow stress models were established from the experimental stress-strain curves, the correlation coefficient (R), mean absolute relative error (MARE), and root mean square deviation (RMSD) between the predicted data and the experimental data were also calculated. The results show that the Fields-Backofen model, which includes a softening factor, was the simplest mathematical expression with a level of precision appropriate for the numerical simulations. However, the Arrhenius and artificial neural network (ANN) models were also consistent with the experimental results but they are more limited in their application in terms of their accuracy and the mathematical expression of the models.

  3. Relationship between fracture toughness, fracture path, and microstructure of 7050 aluminum alloy. Part 1: Quantitative characterization

    SciTech Connect

    Deshpande, N.U.; Gokhale, A.M.; Denzer, D.K.; Liu, J.

    1998-04-01

    The fracture toughness of Al-Zn-Mg-Cu-based 7XXX aluminum alloys decreases with an increase in the extent of recrystallization. In this contribution, the fracture path of plane-strain fracture-toughness specimens of 7050 alloy (a typical alloy of the 7XXX series) is quantitatively characterized as a function of degree of recrystallization, specimen orientation, and aging condition. The fracture path is quantitatively correlated to fracture toughness, and the bulk microstructural attributes estimated via sterological analysis. In the companion article, these quantitative data are used to develop and verify a multiple-fracture micromechanism-based model that relates the fracture toughness to a number of microstructural parameters of the partially recrystallized alloy plate.

  4. Effect of grain size on the superplastic behavior of a 7475 aluminum alloy

    SciTech Connect

    Mahidhara, R.K.

    1995-12-01

    Specimens of a superplastic 7475 aluminum alloy with grain sizes ranging between 9 and 35 {micro}m were tensile tested at a strain rate of 1 {times} 10{sup {minus}4}/s at 457 and 517 C. At 517 C, the ductility was found to decrease with an increase in grain size. At 457 C, on the other hand, the ductility was found to increase initially and then decrease for grain sizes larger than 14 {micro}m. The latter decrease in ductility is attributed to the lowered ability for grain-boundary sliding with decreasing grain-boundary area. In the as-received material (grain size of 9 {micro}m), the observed low ductility is attributed to an inhomogeneous microstructure.

  5. Intergranular fracture in some precipitation-hardened aluminum alloys at low temperatures

    SciTech Connect

    Kuramoto, S.; Itoh, G.; Kanno, M.

    1996-10-01

    Intergranular fracture at low temperatures from room temperature down to 4.2 K has been studied in some precipitation-hardened aluminum alloys. Microscopic appearance of intergranular facets is revealed to be greatly affected by the microstructure adjacent to the grain boundaries (GBs). When large precipitates on GBs and wide precipitation-free zones (PFZs) are present, coalescence of microvoids initiated at the GB precipitates causes the intergranular fracture with dimples. This fracture process is found to be unaffected by deformation temperature. On the other hand, in the presence of fine precipitates on GBs and narrow PFZs, matrix slip localization exerts significant influence on the fracture behavior. At low temperatures, large stress concentration at GBs leads to intergranular fracture, forming sharp ledges on the fracture surfaces, while at room temperature, the dynamic recovery process is thought to relax such stress concentration, resulting in a transgranular ductile rupture.

  6. Thermomechanical treatment of 2124 PM aluminum alloys with low and high dispersoid levels

    NASA Technical Reports Server (NTRS)

    Sarkar, B.; Lisagor, W. B.

    1986-01-01

    The effects of thermomechanical treatment (TMT) on the mechanical properties and metallurgical structure of 2124 powder metallurgy aluminum alloys prepared from rapidly solidified powders were investigated. The alloys were prepared by using a standard canning/vacuum degassing/hot consolidation/extrusion sequence. Two compositions, with manganese contents of 0.5 and 1.5 percent, were investigated to examine the effects of low and high dispersoid levels. The results indicate that significant improvements in strength can be accomplished through TMT for this PM alloy system with little loss in toughness. The increase in strength observed is attributed to the presence of much finer, more homogeneous S-prime precipitation than that observed without TMT. Rolling deformation at room temperature resulted in some tendency for nonuniform (planar) deformation and resulted in slightly lower notch strength values. The lower notch strengths observed in the higher manganese composition were attributed to the coarser, more dense dispersoids observed in this material.

  7. Composition and orientation relationships of constituent particles in 3xxx aluminum alloys

    NASA Astrophysics Data System (ADS)

    Muggerud, Astrid Marie F.; Li, Yanjun; Holmestad, Randi

    2014-02-01

    Constituent and dispersoid phases in two Direct Chill-cast 3xxx aluminum alloys after low-temperature annealing, with different silicon content have been studied. The lattice parameters, chemical composition, morphology and orientations relationships of constituent particles with regard to Al matrix have been addressed. Al?(Fe,Mn) is found to be the most prominent constituent phase in the alloy with a low Si content. The orientation relationship between aluminum matrix and this phase is determined as ?, ?, which is consistent with the orientation relationships of Al?(Fe,Mn) dispersoids. ?-Al(Fe,Mn)Si constituent particles in the Si rich alloy have been found to have various possible orientations. A gradient of Fe content is found in the ?-Al(Fe,Mn)Si dispersoids due to slow diffusion of Fe into dispersoids during annealing.

  8. [Texture variation of CC 5052 aluminum alloy slab from surface to center layer by XRD].

    PubMed

    Chen, Ming-Biao; Liu, Wen-Chang; Ma, Xiao-Yi; Li, Jian; Yang, Qing-Xiang; Wang, Shan; Ma, Min; Liu, Chang; Zhao, Y M

    2013-05-01

    For improvement of the processing and gaining uniformity texture structure and performance of direct chill cast CCAA 5052 aluminum alloy band after first hot rolling with different reduction, the material was annealed at 454 degrees C and then cold rolling with different reduction was conducted, the texture at surface, quarter and center layer of the sample was tested and examined by X-ray diffraction method, the data calculated using special software and the difference of texture at surface, quarter and center layer was analyzed. There existed an elevated gradient of intensity from surface layer to center layer after cold rolled with less than or equal to 40% reduction, The main texture of beta is stronger mainly due to transformation from remainder exposure, while the goss and remainder is infirm, the state of texture at each layer is close to each other after cold rolling with reduction high than 56.1%. PMID:23905353

  9. [Texture variation of DCAA 5052 aluminum alloy slab at difference position through thickness by XRD].

    PubMed

    Chen, Ming-Bia; Liu, Wen-Chang; Li, Jian; Ma, Xiao-Yi; Ma, Wen; Liu, Chang; Li, Jing; Du, Wen-Wen; Man, Qi-Sing

    2012-11-01

    For improvement the processing and gaining uniformity texture structure and performance the thickness direction of direct chill cast DCAA 5052 aluminum alloy band after first hot rolling with different reduction, the material was annealed at 454 degrees C and then cold rolling with different reduction, we test and examined the texture at surface, quarter and center layer of the sample by use X-ray diffraction method, we calculated the data by use special software and analyses the difference texture at surface, quarter and center layer. The intension gradient of beta texture was along the direction from surface to center layer gradually enhance at different reduction sample. For beta texture, the intension gradient was along the direction from surface to center layer gradually reduce, the volume fraction gradually augment and the intensity gradually were almost equal with the cold rolling reduction increased from 0% to 90%. PMID:23387192

  10. Scale Rules for Macrosegregation during Direct-Chill Casting of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Eskin, Dmitry G.; Du, Qiang; Katgerman, Laurens

    2008-05-01

    An analysis of published experimental and numerical results shows that there is a scaling relationship between the magnitude and direction of centerline segregation in direct-chill (DC) cast billets from aluminum alloys and the process parameters, i.e., billet diameter and casting speed. It seems that there is always a range of these process parameters where the centerline segregation is positive, and there is a threshold when the centerline segregation vanishes. Numerical simulations of macrosegregation during DC casting of a binary Al-Cu alloy were performed at different ratios of casting speed and billet diameter. The macrosegregation model takes into account only two mechanisms of macrosegregation, i.e., thermosolutal convection and shrinkage-induced flow. The results of these computer simulations fit well to the dependence obtained using numerous reference data. The results are discussed in terms of the contribution of different mechanisms of macrosegregation and the shape of the billet sump.

  11. Computer simulation of solidification cracking in high strength aluminum alloys: Basic concepts and approach

    SciTech Connect

    Chang, K.M.; Lu, H.M.; Wan, J.; Harris, J.F.

    1996-12-31

    High-strength aluminum ingots are sensitive to hot cracking during solidification, and many finite element modelings have been applied to the solidification process of ingot casting. Most simulations can predict the thermal profile and thermal history quite accurately, but very few works succeed in estimating precise distribution of thermal stress because of no valid thermomechanical properties in the as-cast structure. As alloy strength is not only a function of temperature but also a function of microstructure which depends on the cooling history of the ingot, a constitutive modeling of these Al-alloys must be obtained by continuous cooling of different rates in the as-cast structure. In this study, methodology for prediction of solidification cracking, which considers cooling dependent properties, is presented, and thermomechanical properties of the as-cast material are measured, and results are employed in the finite element simulation of direct-chill casting of 7050 aluminum alloys to calculate thermal stress.

  12. Beam and Torsion Tests of Aluminum-alloy 61S-T Tubing

    NASA Technical Reports Server (NTRS)

    Moore, R L; Holt, Marshall

    1942-01-01

    Tests were made to determine the effect of length and the effect of ratios of diameter to wall thickness upon the flexural and torsional moduli of failure of 61S-T aluminum-alloy tubing. The moduli of failure in bending, as determined by tests in which the tubing was loaded on the neutral axis at the one-third points of the span, were found to bear an approximately linear relationship with diameter-thickness ratio and were practically independent of span within the limits investigated. Empirical equations are given describing the relations obtained. The moduli of failure in torsion were found to be dependent upon length as well as upon diameter-thickness ratios. Empirical equations are given for predicting strengths within the range of plastic buckling. Within the elastic range, available torsion theories were found to be satisfactory.

  13. High Strength and Wear Resistant Aluminum Alloy for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    In this paper, a new high strength and wear resistant aluminum cast alloy invented by NASA-MSFC for high temperature applications will be presented. Developed to meet U.S. automotive legislation requiring low-exhaust emission, the novel NASA 398 aluminum-silicon alloy offers dramatic improvement in tensile and fatigue strengths at elevated temperatures (500 F-800 F), enabling new pistons to utilize less material, which can lead to reducing part weight and cost as well as improving performance. NASA 398 alloy also offers greater wear resistance, surface hardness, dimensional stability, and lower thermal expansion compared to conventional aluminum alloys for several commercial and automotive applications. The new alloy can be produced economically using permanent steel molds from conventional gravity casting or sand casting. The technology was developed to stimulate the development of commercial aluminum casting products from NASA-developed technology by offering companies the opportunity to license this technology.

  14. Computerized simulation of grain boundary character in a superplastic aluminum alloy

    SciTech Connect

    McNelley, T.R.; Perez-Prado, M.T.

    2000-07-01

    High-angle grain boundaries are generally deemed necessary for superplasticity in metals. In polycrystalline materials the grain boundary character must be described in terms of a probability distribution rather than by a single parameter, and little has been reported on the relationship between this distribution and fine-grain superplasticity. For aluminum alloys that exhibit continuous recrystallization the results of computer-aided electron backscatter diffraction analysis have shown that bimodal grain boundary disorientation distributions are present in as-processed material and persist during subsequent annealing. Such distributions may be simulated by computer methods based on a model of the microstructure which assumes that deformation banding occurs during deformation processing. High-angle boundaries ({ge} 30{degree}) develop in association with deformation banding while boundaries of lower disorientation (< 30{degree}) develop by dislocation reaction within the bands. Improved understanding of the grain boundary types associated with various microstructural transformation mechanisms will aid the design of processes to produce superplastic microstructures.

  15. An Investigation into the Effect of Aging on the Forming Limit Diagram of 6063 Aluminum Alloy

    SciTech Connect

    Hosseini, S. M.; Hosseimpour, S. J.; Nourouzi, S.; Gorji, A. H.

    2011-01-17

    In this study, the effect of ageing on the forming limit diagram of a commercially available 6063 aluminum alloy has been investigated. For this purpose, initially the specimens have been aged at 200 deg. C and at various times. The hardness tests have been carried out and the hardness-aging time curve has been obtained for this alloy. Moreover, the mechanical properties were determined by tensile test. Then, the forming limit diagrams have been achieved by using the out-of-plane formability test method at four different conditions containing: annealed, under-aged, peak-aged, and over-aged. The results indicate that in comparing with the annealed condition the FLD{sub 0} decreases significantly from the under-aged condition to the peak-aged condition and increases slightly from the peak-aged condition to the over-aged condition.

  16. Influence of deformation ageing treatment on microstructure and properties of aluminum alloy 2618

    SciTech Connect

    Wang Jianhua Yi Danqing; Su Xuping; Yin Fucheng

    2008-07-15

    The effects of deformation ageing treatment (DAT) on the microstructure and properties of aluminum alloy 2618 were investigated. The alloy was subjected to deformation ageing treatment which included solution treating at 535 deg. C quenching into water at room-temperature, cold rolling (10%) and further ageing to peak hardness level at 200 deg. C. The electron microscopic studies revealed that the treatment affects the ageing characteristics and the coarsening of ageing phase (S') at elevated-temperature. The dislocation-precipitate tangles substructure couldn't be found in alloy 2618. The tensile and hardness tests showed that deformation-ageing treatment causes a significant improvement in tensile strength and hardness to alloy 2618 at room- and elevated-temperature.

  17. Residual Static Strength of ALuminum-Alloy Beams Containing Fatigue Cracks in the Tension Covers

    NASA Technical Reports Server (NTRS)

    Leybold, Herbert A.

    1961-01-01

    Static tests were performed on 31 box beams containing fatigue cracks in order to determine their residual static strengths. The beams were constructed of 7075 and 2024 aluminum alloy according to several designs and employed stringers that were either bonded, riveted, or an integral part of the skin. skin (both aaterials) had the highest residual static strengths, whereas 7075 beams with integrally stiffened covers had the lowest residual static strengths. Except for the integrally stiffened beams, the skin material did not contribute to the residual static strength of the beams because the crack propagated across the skin before maximum load was reached. For the integrally stiffened beams, crack propagation and failure were synonymous. The test results are compared with predictions of the residual static strength. Fair agreement between predicted strength and actual strength was obtained for all beams tested.

  18. Low temperature deformation behavior of an electromagnetically bulged 5052 aluminum alloy.

    PubMed

    Li, Zu; Li, Ning; Wang, Duzhen; Ouyang, Di; Liu, Lin

    2016-01-01

    The fundamental understanding of the deformation behavior of electromagnetically formed metallic components under extreme conditions is important. Here, the effect of low temperature on the deformation behavior of an electromagnetically-bulged 5052 aluminum alloy was investigated through uniaxial tension. We found that the Portevin-Le Chatelier Effect, designated by the serrated characteristic in stress-strain curves, continuously decays until completely disappears with decreasing temperature. The physical origin of the phenomenon is rationalized on the basis of the theoretical analysis and the Monte Carlo simulation, which reveal an increasing resistance to dislocation motion imposed by lowering temperature. The dislocations are captured completely by solute atoms at -50 °C, which results in the extinction of Portevin-Le Chatelier. The detailed mechanism responsible for this process is further examined through Monte Carlo simulation. PMID:27426919

  19. Thermal Management in Friction-Stir Welding of Precipitation-Hardened Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Upadhyay, Piyush; Reynolds, Anthony P.

    2015-05-01

    Process design and implementation in friction-stir welding (FSW) is mostly dependent on empirical information. Basic science of FSW and processing can only be complete when fundamental interrelationships between the process control parameters and response variables and the resulting weld microstructure and properties are established to a reasonable extent. It is known that primary process control parameters such as tool rotation, translation rates, and forge axis force have complicated and interactive relationships to process-response variables such as peak temperature and time at temperature. Of primary influence on the other process-response parameters are temperature and its gradient in the deformation and heat-affected zones. Through a review of pertinent works in the literature and results from boundary condition experiments performed in precipitation-hardening aluminum alloys, this article partially elucidates the nature and effects of temperature transients caused by variation of thermal boundaries in FSW.

  20. Stability of the grain structure in 2219-O aluminum alloy friction stir welds during solution treatment

    SciTech Connect

    Chen, Y.C. . E-mail: armstrong@hit.edu.cn; Feng, J.C.; Liu, H.J.

    2007-02-15

    The stability of the grain structure in 2219-O aluminum alloy friction stir welds during solution treatment has been investigated. Experimental results show that the solution treatment causes drastic grain growth, Grain growth initiates at the surface and the bottom of the weld and then extends to the weld centre within several minutes. The solution treatment temperature and the welding heat input have a significant effect on grain growth. The higher the solution temperature, or the higher the welding heat input, the greater the grain growth. The instability of the grains is attributed to an imbalance between thermodynamic driving forces for grain growth and the pinning forces impeding grain boundary migration during solution treatment.

  1. A study on the re-solution heat treatment of AA 2618 aluminum alloy

    SciTech Connect

    Ozbek, Ibrahim . E-mail: iozbek@sakarya.edu.tr

    2007-03-15

    In the present study, the effects of re-solution treatment of AA2618 aluminum alloy has been investigated. Solution heat treatments of 520-640 deg. C for 14-24 h were applied followed by artificial aging. Characterization studies that were carried out by optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy techniques showed that recrystallisation was not observed by solution treatment at 530 deg. C whereas it did occur as the solution treatment and the duration time were increased above 530 deg. C. Increasing the solution treatment temperature further coarsened both the grains and the precipitates, resulting in significant reduction in hardness. Al{sub 9}FeNi-type intermetallics are not completely dissolved by these solution treatments.

  2. Selection of a Microbiological Corrosion System for Studying Effects on Structural Aluminum Alloys

    PubMed Central

    Hedrick, H. G.; Miller, C. E.; Halkias, J. E.; Hildebrand, J. E.

    1964-01-01

    Two laboratory methods, a metal-strip test and a tank test, were evaluated as microbiological corrosion systems for producing corroded test specimens on a structural aluminum alloy. The results show that corrosion of the test alloy occurred best in the metal-strip test in a deionized water-fuel medium inoculated with a mixture of microorganisms under aerated conditions. The metal-strip test was more successful for producing large numbers of corroded test specimens and proved more economical than the tank-type test, since less structural material is needed to obtain a specimen with sufficient corrosion areas, and since the corrosion can more easily be restricted by maskants to certain areas for specific test purposes. Images FIG. 1 FIG. 2 FIG. 3 FIG. 4 FIG. 5 FIG. 6 FIG. 7 FIG. 8 FIG. 9 FIG. 10 FIG. 11 FIG. 12 FIG. 13 PMID:16349646

  3. Long-Term Atmospheric Corrosion of Aluminum Alloy 2024-T4 in a Coastal Environment

    NASA Astrophysics Data System (ADS)

    Zhang, Teng; He, Yuting; Cui, Ronghong; An, Tao

    2015-07-01

    Aluminum alloy 2024-T4 specimens were exposed to atmosphere for 7, 12, and 20 years, respectively, to study long-term corrosion in a coastal environment. One-directional corrosion region and cross-directional corrosion region were defined according to corrosion characters. The statistical regularities, surface appearance, corrosion products, and cross-sectional morphology of both regions were investigated. It was found that the minimum remaining thicknesses of each region can be described by a normal distribution and linearly decrease as the exposure time is increased from 7 to 20 years. The corrosion pits, chlorine ions, and interlinked inner pits are promoting exfoliation, and the alloy's corrosion susceptibility along the long transverse direction is strongly location dependent due to the restrictions imposed by the side material.

  4. Selection of a Microbiological Corrosion System for Studying Effects on Structural Aluminum Alloys.

    PubMed

    Hedrick, H G; Miller, C E; Halkias, J E; Hildebrand, J E

    1964-05-01

    Two laboratory methods, a metal-strip test and a tank test, were evaluated as microbiological corrosion systems for producing corroded test specimens on a structural aluminum alloy. The results show that corrosion of the test alloy occurred best in the metal-strip test in a deionized water-fuel medium inoculated with a mixture of microorganisms under aerated conditions. The metal-strip test was more successful for producing large numbers of corroded test specimens and proved more economical than the tank-type test, since less structural material is needed to obtain a specimen with sufficient corrosion areas, and since the corrosion can more easily be restricted by maskants to certain areas for specific test purposes. PMID:16349646

  5. Effect of intermetallic phases on the anodic oxidation and corrosion of 5A06 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Li, Song-mei; Li, Ying-dong; Zhang, You; Liu, Jian-hua; Yu, Mei

    2015-02-01

    Intermetallic phases were found to influence the anodic oxidation and corrosion behavior of 5A06 aluminum alloy. Scattered intermetallic particles were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) after pretreatment. The anodic film was investigated by transmission electron microscopy (TEM), and its corrosion resistance was analyzed by electrochemical impedance spectroscopy (EIS) and Tafel polarization in NaCl solution. The results show that the size of Al-Fe-Mg-Mn particles gradually decreases with the iron content. During anodizing, these intermetallic particles are gradually dissolved, leading to the complex porosity in the anodic film beneath the particles. After anodizing, the residual particles are mainly silicon-containing phases, which are embedded in the anodic film. Electrochemical measurements indicate that the porous anodic film layer is easily penetrated, and the barrier plays a dominant role in the overall protection. Meanwhile, self-healing behavior is observed during the long immersion time.

  6. A fracture criterion for widespread cracking in thin-sheet aluminum alloys

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.; Dawicke, D. S.; Sutton, M. A.; Bigelow, C. A.

    1993-01-01

    An elastic-plastic finite-element analysis was used with a critical crack-tip-opening angle (CTOA) fracture criterion to model stable crack growth in thin-sheet 2024-T3 aluminum alloy panels with single and multiple-site damage (MSD) cracks. Comparisons were made between critical angles determined from the analyses and those measured with photographic methods. Calculated load against crack extension and load against crack-tip displacement on single crack specimens agreed well with test data even for large-scale plastic deformations. The analyses were also able to predict the stable tearing behavior of large lead cracks in the presence of stably tearing MSD cracks. Small MSD cracks significantly reduced the residual strength for large lead cracks.

  7. Nanostructured lithium-aluminum alloy electrodes for lithium-ion batteries.

    SciTech Connect

    Hudak, Nicholas S.; Huber, Dale L.

    2010-12-01

    Electrodeposited aluminum films and template-synthesized aluminum nanorods are examined as negative electrodes for lithium-ion batteries. The lithium-aluminum alloying reaction is observed electrochemically with cyclic voltammetry and galvanostatic cycling in lithium half-cells. The electrodeposition reaction is shown to have high faradaic efficiency, and electrodeposited aluminum films reach theoretical capacity for the formation of LiAl (1 Ah/g). The performance of electrodeposited aluminum films is dependent on film thickness, with thicker films exhibiting better cycling behavior. The same trend is shown for electron-beam deposited aluminum films, suggesting that aluminum film thickness is the major determinant in electrochemical performance regardless of deposition technique. Synthesis of aluminum nanorod arrays on stainless steel substrates is demonstrated using electrodeposition into anodic aluminum oxide templates followed by template dissolution. Unlike nanostructures of other lithium-alloying materials, the electrochemical performance of these aluminum nanorod arrays is worse than that of bulk aluminum.

  8. The column strength of aluminum alloy 75S-T extruded shapes

    NASA Technical Reports Server (NTRS)

    Holt, Marshall; Leary, J R

    1946-01-01

    Because the tensile strength and tensile yield strength of alloy 75S-T are appreciably higher than those of the materials used in the tests leading to the use of the straight-line column curve, it appeared advisable to establish the curve of column strength by test rather than by extrapolation of relations determined empirically in the earlier tests. The object of this investigation was to determine the curve of column strength for extruded aluminum alloy 75S-T. In addition to three extruded shapes, a rolled-and-drawn round rod was included. Specimens of various lengths covering the range of effective slenderness ratios up to about 100 were tested.

  9. Improved TIG weld joint strength in aluminum alloy 2219-T87 by filler metal substitution

    NASA Technical Reports Server (NTRS)

    Poorman, R. M.; Lovoy, C. V.

    1972-01-01

    The results of an investigation on weld joint characteristics of aluminum alloy 2219-T87 are given. Five different alloys were utilized as filler material. The mechanical properties of the joints were determined at ambient and cryogenic temperatures for weldments in the as-welded condition and also, for weldments after elevated temperature exposures. Other evaluations included hardness surveys, stress corrosion susceptibility, and to a limited extent, the internal metallurgical weld structures. The overall results indicate that M-943 filler weldments are superior in strength to weldments containing either the standard 2319 filler or fillers 2014, 2020, and a dual wire feed consisting of three parts 2319 and one part 5652. In addition, no deficiencies were evident in M-934 filler weldments with regard to ductility, joint strength after elevated temperature exposure, weld hardness, metallographic structures, or stress corrosion susceptibility.

  10. Low temperature deformation behavior of an electromagnetically bulged 5052 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Li, Zu; Li, Ning; Wang, Duzhen; Ouyang, Di; Liu, Lin

    2016-07-01

    The fundamental understanding of the deformation behavior of electromagnetically formed metallic components under extreme conditions is important. Here, the effect of low temperature on the deformation behavior of an electromagnetically-bulged 5052 aluminum alloy was investigated through uniaxial tension. We found that the Portevin-Le Chatelier Effect, designated by the serrated characteristic in stress-strain curves, continuously decays until completely disappears with decreasing temperature. The physical origin of the phenomenon is rationalized on the basis of the theoretical analysis and the Monte Carlo simulation, which reveal an increasing resistance to dislocation motion imposed by lowering temperature. The dislocations are captured completely by solute atoms at ‑50 °C, which results in the extinction of Portevin-Le Chatelier. The detailed mechanism responsible for this process is further examined through Monte Carlo simulation.

  11. Nanoscale microstructure effects on hydrogen behavior in rapidly solidified aluminum alloys

    SciTech Connect

    Tashlykova-Bushkevich, Iya I.

    2015-12-31

    The present work summarizes recent progress in the investigation of nanoscale microstructure effects on hydrogen behavior in rapidly solidified aluminum alloys foils produced at exceptionally high cooling rates. We focus here on the potential of modification of hydrogen desorption kinetics in respect to weak and strong trapping sites that could serve as hydrogen sinks in Al materials. It is shown that it is important to elucidate the surface microstructure of the Al alloy foils at the submicrometer scale because rapidly solidified microstructural features affect hydrogen trapping at nanostructured defects. We discuss the profound influence of solute atoms on hydrogen−lattice defect interactions in the alloys. with emphasis on role of vacancies in hydrogen evolution; both rapidly solidified pure Al and conventionally processed aluminum samples are considered.

  12. Proof test and fatigue crack growth modeling on 2024-T3 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.; Poe, C. C., Jr.; Dawicke, D. S.

    1990-01-01

    Pressure proof testing of aircraft fuselage structures has been suggested as a means of screening critical crack sizes and of extending their useful life. The objective of this paper is to study the proof-test concept and to model the crack-growth process on a ductile material. Simulated proof and operational fatigue life tests have been conducted on cracked panels made of 2024-T3 aluminum alloy sheet material. A fatigue crack-closure model was modified to simulate the proof test and operational fatigue cycling. Using crack-growth rate and resistance-curve data, the model was able to predict crack growth during and after the proof load. These tests and analyses indicate that the proof test increases fatigue life; but the beneficial life, after a 1.33 or 1.5 proof, was less than a few hundred cycles.

  13. The development of a fluidized bed process for the heat treatment of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Keist, Jay

    2005-04-01

    Heat treating of aluminum alloys is often necessary to achieve the mechanical properties required for a part. With conventional furnaces, though, the heat-treating process requires several hours and manufacturers have traditionally utilized off-line, batch heat-treating operations. The long cycle times required for heat treating with conventional systems go contrary to lean manufacturing where the goal is to reduce the time a part spends in the factory. The fluidized bed technology offers rapid heating rates and excellent temperature control that allows one to significantly reduce the time required for heat treating by an order of magnitude. Technomics developed a fluidized bed conveying system that allows the manufacturer to bring the heat-treating system in-line with the casting or forging operation, obtaining a true lean manufacturing process.

  14. Stress Corrosion Cracking Study of Aluminum Alloys Using Electrochemical Noise Analysis

    NASA Astrophysics Data System (ADS)

    Rathod, R. C.; Sapate, S. G.; Raman, R.; Rathod, W. S.

    2013-12-01

    Stress corrosion cracking studies of aluminum alloys AA2219, AA8090, and AA5456 in heat-treated and non heat-treated condition were carried out using electrochemical noise technique with various applied stresses. Electrochemical noise time series data (corrosion potential vs. time) was obtained for the stressed tensile specimens in 3.5% NaCl aqueous solution at room temperature (27 °C). The values of drop in corrosion potential, total corrosion potential, mean corrosion potential, and hydrogen overpotential were evaluated from corrosion potential versus time series data. The electrochemical noise time series data was further analyzed with rescaled range ( R/ S) analysis proposed by Hurst to obtain the Hurst exponent. According to the results, higher values of the Hurst exponents with increased applied stresses showed more susceptibility to stress corrosion cracking as confirmed in case of alloy AA 2219 and AA8090.

  15. Homogeneity of Mechanical Properties of Underwater Friction Stir Welded 2219-T6 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Liu, H. J.; Zhang, H. J.; Yu, L.

    2011-11-01

    Underwater friction stir welding (FSW) has been demonstrated to be available for the improvement in tensile strength of normal FSW joints. In order to illuminate the intrinsic reason for strength improvement through underwater FSW, a 2219 aluminum alloy was underwater friction stir welded and the homogeneity of mechanical properties of the joint was investigated by dividing the joint into three layers. The results indicate that the tensile strength of the three layers of the joint is all improved by underwater FSW, furthermore, the middle and lower layers have larger extent of strength improvement than the upper layer, leading to an increase in the homogeneity of mechanical properties of the joint. The minimum hardness value of each layer, especially the middle and lower layers, is improved under the integral water cooling effect, which is the intrinsic reason for the strength improvement of underwater joint.

  16. Low strain creep and aging of aluminum alloy 2219-T87 sheet

    NASA Technical Reports Server (NTRS)

    Navrotski, G.; Rummler, D. R.

    1981-01-01

    The constant load creep and isothermal aging characteristics of aluminum alloy 2219-T87 sheet have been studied experimentally and analytically in the temperature range 250 to 650 F at stress levels between 2.9 and 4.0 ksi (20 to 283 MPa). Testing variables were closely and automatically monitored. The data generated agree somewhat with the literature data base at lower temperatures, but above 500 F, discrepancies of greater than an order of magnitude in the time to 1% creep strain occur. Good correlation was found with the Larson-Miller parameter as modeled by a second-order polynomial in stress. Constitutive equations for time to 0.1%, 0.2%, 0.5%, and 1.0% creep are given. Information on residual mechanical properties and electrical conductivity is also provided.

  17. Role of Laser Cladding Parameters in Composite Coating (Al-SiC) on Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Riquelme, Ainhoa; Escalera-Rodriguez, María Dolores; Rodrigo, Pilar; Rams, Joaquin

    2016-08-01

    The effect of the different control parameters on the laser cladding fabrication of Al/SiCp composite coatings on AA6082 aluminum alloy was analyzed. A high-power diode laser was used, and the laser control parameters were optimized to maximize the size (height and width) of the coating and the substrate-coating interface quality, as well as to minimize the melted zone depth. The Taguchi DOE method was applied using a L18 to reduce the number of experiments from 81 to only 18 experiments. Main effects, signal-noise ratio and analysis of variance were used to evaluate the effect of these parameters in the characteristics of the coating and to determine their optimum values. The influence of four control parameters was evaluated: (1) laser power, (2) scanning speed, (3) focal condition, and (4) powder feed ratio. Confirmation test with the optimal control parameters was carried out to evaluate the Taguchi method's effectivity.

  18. Thermal Management in Friction-Stir Welding of Precipitation-Hardening Aluminum Alloys

    SciTech Connect

    Upadhyay, Piyush; Reynolds, Anthony

    2015-05-25

    Process design and implementation in FSW is mostly dependent on empirical information gathered through experience. Basic science of friction stir welding and processing can only be complete when fundamental interrelationships between process control parameters and response variables and resulting weld microstructure and properties are established to a reasonable extent. It is known that primary process control parameters like tool rotation and translation rate and forge axis force have complicated and interactive relationships to the process response variables such as peak temperature, time at temperature etc. Of primary influence to the other process response parameters are temperature and its gradient at the deformation and heat affected zones. Through review of pertinent works in the literature and some experimental results from boundary condition work performed in precipitation hardening aluminum alloys this paper will partially elucidate the nature and effects of temperature transients caused by variation of thermal boundaries in Friction Stir Welding.

  19. The effect of corrosion on the fatigue life of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Dalla, P. T.; Tragazikis, I. K.; Exarchos, D. A.; Matikas, T. E.

    2016-04-01

    The corrosion behavior of metallic structures is an important factor of material performance. In case of aluminum matrix composites corrosion occurs via electrochemical reactions at the interface between the metallic matrix and the reinforcement. The corrosion rate is determined by equilibrium between two opposing electrochemical reactions, the anodic and the cathodic. When these two reactions are in equilibrium, the flow of electrons from each reaction type is balanced, and no net electron flow occurs. In the present study, aluminum alloy tensile-shape samples are immersed in NaCl solution with an objective to study the effect of the controlled pitting corrosion in a specific area. The rest of the material is completely sealed. In order to investigate the effect of pitting corrosion on the material performance, the specimens were subjected to cyclic loading. The effect of corrosion on the fatigue life was assessed using two complimentary nondestructive methods, infrared thermography and acoustic emission.

  20. Stress Ratio Effects on Crack Opening Loads and Crack Growth Rates in Aluminum Alloy 2024

    NASA Technical Reports Server (NTRS)

    Riddell, William T.; Piascik, Robert S.

    1998-01-01

    The effects of stress ratio (R) and crack opening behavior on fatigue crack growth rates (da/dN) for aluminum alloy (AA) 2024-T3 were investigated using constant-delta K testing, closure measurements, and fractography. Fatigue crack growth rates were obtained for a range of delta K and stress ratios. Results show that constant delta K fatigue crack growth for R ranging from near 0 to 1 is divided into three regions. In Region 1, at low R, da/dN increases with increasing R. In Region 2, at intermediate R, fatigue crack growth rates are relatively independent of R. In Region 3, at high R, further increases in da/dN are observed with increasing R.

  1. Accelerated Threshold Fatigue Crack Growth Effect-Powder Metallurgy Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Piascik, R. S.; Newman, J. A.

    2002-01-01

    Fatigue crack growth (FCG) research conducted in the near threshold regime has identified a room temperature creep crack growth damage mechanism for a fine grain powder metallurgy (PM) aluminum alloy (8009). At very low (Delta) K, an abrupt acceleration in room temperature FCG rate occurs at high stress ratio (R = K(sub min)/K(sub max)). The near threshold accelerated FCG rates are exacerbated by increased levels of K(sub max) (K(sub max) = 0.4 K(sub IC)). Detailed fractographic analysis correlates accelerated FCG with the formation of crack-tip process zone micro-void damage. Experimental results show that the near threshold and K(sub max) influenced accelerated crack growth is time and temperature dependent.

  2. Structure and Hardness of 01570 Aluminum Alloy Friction Stir Welds Processed Under Different Conditions

    NASA Astrophysics Data System (ADS)

    Il'yasov, R. R.; Avtokratova, E. V.; Markushev, M. V.; Predko, P. Yu.; Konkevich, V. Yu.

    2015-10-01

    Structure and hardness of the 01570 aluminum alloy joints processed by friction stir welding at various speeds are investigated. It is shown that increasing the traverse tool speed lowers the probability of macrodefect formation in the nugget zone; however, this can lead to anomalous grain growth in the zone of contact with the tool shoulder. Typical "onion-like" structure of the weld consisting of rings that differ by optical contrast is formed for all examined welding regimes. It is demonstrated that this contrast is caused by the difference in the grain sizes in the rings rather than by their chemical or phase composition. Mechanisms of transformation of the alloy structure during friction stir welding are discussed.

  3. Aluminum alloy 6013 sheet for new U.S. Navy aircraft

    NASA Astrophysics Data System (ADS)

    Kaneko, R. S.; Bakow, L.; Lee, E. W.

    1990-05-01

    The recently developed aluminum alloy 6013-T6 has been selected for the fuselage skin and other applications on the U.S. Navy's P-7A airplane, in place of the traditional 2024-T3 clad sheet. Alloy 6013-T6 is naturally corrosion resistant, like the well-established alloy 6061, and hence is used unclad. Its fatigue strength, fatigue crack growth and fracture toughness compare favorably with 2024-T3. Replacement of alloy 2024 with alloy 6013 also reduces manufacturing costs for formed parts, because 6013 is readily formed in the T4 temper, then simply aged to T6, thus avoiding the costly heat treatments and straightening required for alloy 2024.

  4. The Strength and Characteristics of VPPA Welded 2219-T87 Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Jemian, W. A.

    1985-01-01

    A study of the variable polarity plasma arc (VPPA) welding process and those factors that control the structure and properties of VPPA welded aluminum alloy 2219-T87 was conducted. The importance of joint preparation, alignment of parts and welding process variables are already established. Internal weld defects have been eliminated. However, a variation of properties was found to be due to the size variation of interdendritic particles in the fusion zone. These particles contribute to the void formation process, which controls the ultimate tensile strength of the welded alloy. A variation of 150 microns in particle size correlated with a 10 ksi variation of ultimate tensile strength. It was found that all fracture surfaces were of the dimple rupture type, with fracture initiating within the fusion zone.

  5. Hydrogenation of deformable aluminum alloy semiproducts during water quenching and artificial aging

    NASA Astrophysics Data System (ADS)

    Antipin, V. P.; Tul'Pakova, R. V.

    2007-10-01

    The surface layers of rods made of magnesium-containing aluminum alloys are shown to undergo strong hydrogenation during water quenching. Hydrogenation is detected during vacuum heating after artificial aging (D16 alloy) or long-term storage (V95, AK4-1ch alloys). Very high hydrogen concentrations in the surface layers of semiproducts that appear in regions with a minimum cooling rate during quenching are likely to cause bubble formation on the surface of the heat-treated semiproducts. Compared to the V95 alloy, hydrogen dissolved in the AK4-1ch alloy rods behaves differently during air annealing. Specifically, hydrogen is rapidly absorbed by the degassed rods and is slowly extracted from the saturated rods. This behavior is most likely to be caused by hydrogen-ion entrapment by FeNiAl9 intermetallic particles.

  6. Surface Roughness Investigation of Ultrafine-Grained Aluminum Alloy Subjected to High-Speed Erosion

    NASA Astrophysics Data System (ADS)

    Kazarinov, N. A.; Evstifeev, A. D.; Petrov, Y. V.; Atroshenko, S. A.; Lashkov, V. A.; Valiev, R. Z.; Bondarenko, A. S.

    2016-07-01

    This study is the first attempt to investigate the influence of severe plastic deformation (SPD) treatment on material surface behavior under intensive erosive conditions. Samples of aluminum alloy 1235 (99.3 Al) before and after high-pressure torsion (HPT) were subjected to intensive erosion by corundum particles accelerated via air flow in a small-scale wind tunnel. Velocity of particles varied from 40 to 200 m/s, while particle average diameter was around 100 μm. Surface roughness measurements provided possibility to compare surface properties of both materials after erosion tests. Moreover, SPD processing appeared to increase noticeably the threshold velocity of the surface damaging process. Additionally, structural analysis of the fracture surfaces of the tested samples was carried out.

  7. Investigation of the plastic fracture of high-strength aluminum alloys

    NASA Technical Reports Server (NTRS)

    Van Stone, R. H.; Merchant, R. H.; Low, J. R., Jr.

    1974-01-01

    In a study of plastic fracture in five high-strength aluminum alloys (2014, 2024, 2124, 7075, and 7079), it has been shown that fracture toughness is affected primarily by the size and volume fraction of the larger (2 to 10 microms) second-phase particles. Certain of these particles crack at small plastic strains, nucleating voids which, with further plastic strain, coalesce to cause fracture. Not all second-phase particles crack at small plastic strains, and qualitative analysis of those which are primarily responsible for void nucleation shows that they contain iron or silicon or both. This result suggests that a reduction in the iron and silicon impurity content of the alloys should improve fracture toughness without loss of strength.

  8. Influence of aging on quench sensitivity effect of 7055 aluminum alloy

    SciTech Connect

    Liu, S.D. Zhang, X.M.; Chen, M.A.; You, J.H.

    2008-01-15

    The influence of aging on quench sensitivity effect of 7055 aluminum alloy was investigated by means of tensile properties and electrical conductivity tests. The microstructures were characterized by optical microscopy (OM) and transmission electron microscopy (TEM). Compared with single aging, duplex aging led to higher mechanical properties and lower electrical conductivity of the air quenched alloy, thus reduced the quench sensitivity effect. This was attributed to the elimination of negative effects due to loss of vacancies during slow quenching by duplex aging, which resulted in a higher density of stable G.P. zones in the matrix. Within the studied temperature 20-100 deg. C, a higher temperature pre-aging was favorable for reducing the quench sensitivity effect and the optimal duplex aging was 100 deg. C/24 h + 121 deg. C/24 h in this work.

  9. 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.

  10. Iron-aluminum alloys having high room-temperature and method for making same

    DOEpatents

    Sikka, V.K.; McKamey, C.G.

    1993-08-24

    A wrought and annealed iron-aluminum alloy is described consisting essentially of 8 to 9.5% aluminum, an effective amount of chromium sufficient to promote resistance to aqueous corrosion of the alloy, and an alloying constituent selected from the group of elements consisting of an effective amount of molybdenum sufficient to promote solution hardening of the alloy and resistance of the alloy to pitting when exposed to solutions containing chloride, up to about 0.05% carbon with up to about 0.5% of a carbide former which combines with the carbon to form carbides for controlling grain growth at elevated temperatures, and mixtures thereof, and the balance iron, wherein said alloy has a single disordered [alpha] phase crystal structure, is substantially non-susceptible to hydrogen embrittlement, and has a room-temperature ductility of greater than 20%.

  11. Iron-aluminum alloys having high room-temperature and method for making same

    DOEpatents

    Sikka, Vinod K.; McKamey, Claudette G.

    1993-01-01

    Iron-aluminum alloys having selectable room-temperature ductilities of greater than 20%, high resistance to oxidation and sulfidation, resistant pitting and corrosion in aqueous solutions, and possessing relatively high yield and ultimate tensile strengths are described. These alloys comprise 8 to 9.5% aluminum, up to 7% chromium, up to 4% molybdenum, up to 0.05% carbon, up to 0.5% of a carbide former such as zirconium, up to 0.1 yttrium, and the balance iron. These alloys in wrought form are annealed at a selected temperature in the range of 700.degree. C. to about 1100.degree. C. for providing the alloys with selected room-temperature ductilities in the range of 20 to about 29%.

  12. The use of surface modification techniques for the corrosion protection of aluminum and aluminum alloys

    SciTech Connect

    Natishan, P.M.; McCafferty, E.; Donovon, E.P.; Hubler, G.K.

    1995-12-31

    Surface modification techniques such as ion beam assisted deposition (IBAD) and radio frequency plasma enhanced chemical vapor deposition (PECVD) offer a means to produce surfaces with unique and improved properties. This paper reviews the advantages of the IBAD and PECVD processes and discusses the preparation and pitting corrosion behavior of IBAD modified aluminum surfaces and PECVD coatings on a 7075 aluminum alloy. Pitting potential values for the base materials and for the base materials with silicon nitride IBAD, tantalum oxide IBAD, or PECVD diamond-like carbon coatings were determined in deaerated 0.1M NaCl solutions. The thickness of the modified region ranged from 0.01 to 5.0 {micro}m. All three coatings improved the resistance to pit initiation.

  13. Constitutive Description of 7075 Aluminum Alloy During Hot Deformation by Apparent and Physically-Based Approaches

    NASA Astrophysics Data System (ADS)

    Mirzadeh, Hamed

    2015-03-01

    Hot flow stress of 7075 aluminum alloy during compressive hot deformation was correlated to the Zener-Hollomon parameter through constitutive analyses based on the apparent approach and the proposed physically-based approach which accounts for the dependence of the Young's modulus and the self-diffusion coefficient of aluminum on temperature. It was shown that the latter approach not only results in a more reliable constitutive equation, but also significantly simplifies the constitutive analysis, which in turn makes it possible to conduct comparative hot working studies. It was also demonstrated that the theoretical exponent of 5 and the lattice self-diffusion activation energy of aluminum (142 kJ/mol) can be set in the hyperbolic sine law to describe the peak flow stresses and the resulting constitutive equation was found to be consistent with that resulted from the proposed physically-based approach.

  14. A novel simple approach to preparation of superhydrophobic surfaces of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Xie, Degang; Li, Wen

    2011-11-01

    A novel two-step methodology is successfully developed to fabricate superhydrophobic surfaces of aluminum alloys. The essential procedure is that samples are first immersed and etched in a boiling aqueous solution of NaOH for 5 min without preprocessing, and then they are modified for 30 min in an ethanol solution of lauric acid, cheaper and more efficient than the fluorinated silane frequently adopted by other researchers. If the concentration of NaOH solution is larger than 5 g/L, the contact angle of the prepared surfaces will be larger than 150° with a negligible hysteresis. Such a fast, low-cost, and reliable method for superhydrophobic surfaces implies significant promising industrial applications.

  15. Controlled Release from Core-Shell Nanoporous Silica Particles for Corrosion Inhibition of Aluminum Alloys

    DOE PAGESBeta

    Jiang, Xingmao; Jiang, Ying-Bing; Liu, Nanguo; Xu, Huifang; Rathod, Shailendra; Shah, Pratik; Brinker, C. Jeffrey

    2011-01-01

    Ceriumore » m (Ce) corrosion inhibitors were encapsulated into hexagonally ordered nanoporous silica particles via single-step aerosol-assisted self-assembly. The core/shell structured particles are effective for corrosion inhibition of aluminum alloy AA2024-T3. Numerical simulation proved that the core-shell nanostructure delays the release process. The effective diffusion coefficient elucidated from release data for monodisperse particles in water was 1.0 × 10 − 14  m 2 s for Ce 3+ compared to 2.5 × 10 − 13  m 2 s for NaCl. The pore size, pore surface chemistry, and the inhibitor solubility are crucial factors for the application. Microporous hydrophobic particles encapsulating a less soluble corrosion inhibitor are desirable for long-term corrosion inhibition.« less

  16. Correlation of stress-wave-emission characteristics with fracture aluminum alloys

    NASA Technical Reports Server (NTRS)

    Hartbower, C. E.; Reuter, W. G.; Morais, C. F.; Crimmins, P. P.

    1972-01-01

    A study to correlate stress wave emission characteristics with fracture in welded and unwelded aluminum alloys tested at room and cryogenic temperature is reported. The stress wave emission characteristics investigated were those which serve to presage crack instability; viz., a marked increase in:(1) signal amplitude; (2) signal repetition rate; and (3) the slope of cumulative count plotted versus load. The alloys were 7075-T73, 2219-T87 and 2014-T651, welded with MIG and TIG using 2319 and 4043 filler wire. The testing was done with both unnotched and part-through-crack (PTC) tension specimens and with 18-in.-dia subscale pressure vessels. In the latter testing, a real time, acoustic emission, triangulation system was used to locate the source of each stress wave emission. With such a system, multiple emissions from a given location were correlated with defects found by conventional nondestructive inspection.

  17. Near surface modification of aluminum alloy induced by laser shock processing

    NASA Astrophysics Data System (ADS)

    Saklakoglu, Nursen; Gencalp Irizalp, Simge; Akman, Erhan; Demir, Arif

    2014-12-01

    This paper investigates the influences of near surface modification induced in 6061-T6 aluminum alloy by laser shock processing (LSP). The present study evaluates LSP with a Q-switched Nd:YAG low power laser using water confinement medium and absorbent overlay on the workpiece. The near surface microstructural change of 6061-T6 alloy after LSP was studied. The residual stress variation throughout the depth of the workpiece was determined. The results showed an improvement of the material resistance to pit formation. This improvement may be attributed to compressive residual stress and work-hardening. The size and number of pits revealed by immersion in an NaOH-HCl solution decreased in comparison with the untreated material.

  18. The failure of notched specimens of boron-fiber reinforced 6061 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Wright, M. A.; Iannuzzi, F. A.

    1974-01-01

    The effect of notches on the strength of boron fiber reinforced 6061 aluminum alloy was determined at room temperature, 300 F, and 600 F. Both unidirectional and cross-plied specimens were tested. The strengths of individual fibers were measured, and upper and lower bounds of composite strength were calculated using bundle theory. Fracture tests were performed on specimens containing center slots of various lengths, and the values of the critical stress intensity factor for initial crack propagation or final failure were calculated. For unidirectional specimens, these parameters depended on thickness; for cross-plied specimens, fairly constant values were obtained at room temperature. The cross-plied material invariably failed at a lower stress as the environmental temperature was raised.

  19. The effect of mechanical surface and heat treatments on the erosion resistance of 6061 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Salik, J.; Buckley, D.; Brainard, W. A.

    1981-01-01

    The effects of both mechanical surface treatments and heat treatments on the erosion resistance of 6061 aluminum alloy were studied in order to gain a better understanding of material properties which affect erosion behavior. It was found that mechanical surface treatments have little or no effect on the erosion resistance. This is due to the formation by particle impact of a work-hardened surface layer, independent of the initial surface condition. The erosion resistance of aluminum single crystals was found to be independent of orientation, which is due to destruction of the surface microstructure and formation of a polycrystalline surface layer by the particle impact as observed by X-ray diffraction. Although on solution treatment of annealed aluminum 6061 the increase in hardness is accompanied by an increase in erosion resistance, precipitation treatment (which causes a further increase in hardness) results in a slightly lower erosion resistance.

  20. Artificial Neural Network Modeling to Evaluate the Dynamic Flow Stress of 7050 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Quan, Guo-zheng; Wang, Tong; Li, Yong-le; Zhan, Zong-yang; Xia, Yu-feng

    2016-02-01

    The flow stress data have been obtained by a set of isothermal hot compression tests, which were carried out in the temperature range of 573-723 K and strain rates of 0.01, 0.1, 1, and 10 s-1 with a reduction of 60% on a Gleeble-1500 thermo-mechanical simulator. On the basis of the experimental data, constitutive equation and an artificial neural network model were developed for the analysis and simulation of the flow behavior of the 7050 aluminum alloy. After training with standard back-propagation learning algorithm, the artificial neural network model has the ability to present the intrinsic relationship between the flow stress and the processing variables. In the present model, the temperature, strain, and strain rate were chosen as inputs, and the flow stress was chosen as output. By comparing the values of correlation coefficient and average absolute relative error, the prediction accuracy of the model and the improved Arrhenius-type model can be evaluated. The results indicated that the well-trained artificial neural network model is more accurate than the improved Arrhenius-type model in predicting the hot compressive behavior of the as-extruded 7050 aluminum alloy. Based on the predicted stress data and experimental stress data, the 3D continuous stress-strain maps at different strains, temperatures, and strain rates were plotted subsequently. Besides, the flow stress values at arbitrary temperature, strain rate, and strain are explicit on the 3D continuous stress-strain maps, which would be beneficial to articulate working processes more validly.

  1. Comparison of thermodynamic databases for 3xx and 6xxx aluminum alloys

    NASA Astrophysics Data System (ADS)

    Ravi, C.; Wolverton, C.

    2005-08-01

    Computational thermodynamics, or Calculation of Phase Diagram (CALPHAD) methods have proven useful in applications to modeling a variety of alloy properties. However, the methods are only as accurate as the thermodynamic databases they use, and two commercial thermodynamic databases exist for aluminum alloys: Thermotech and Computherm. In order to provide a critical comparison of these databases, we used both the databases to calculate equilibrium solid-state phase fractions and phase diagram isothermal sections of several industrial aluminum alloys: a 319-type and 356 cast alloys, as well as the wrought alloys 6022 and 6111. All of these alloys may be generically described as being based on the Al-Mg-Si-Cu quaternary with other additions such as Fe, Mn, and Zn. Although many of the results are consistent between the two databases, several qualitative and quantitative differences were observed. Many of these differences are found to be due to the intermetallic compounds involving Fe, Mn, Cr, and Zn. On the other hand, thermodynamics involving only phases from the Al-Mg-Si-Cu quaternary show good agreement between the databases, although some small differences still exist, particularly involving the quaternary Q phase. To understand and assess these differences, formation enthalpies and reaction energies from the databases were compared against density functional first-principles energetics. These comparisons indicate possible avenues for future improvements of Al-alloy thermodynamic databases. Finally, we demonstrate an interesting correlation between the calculated phase fractions and the measured yield strengths across this wide family of 3xx cast and 6xxx wrought alloys.

  2. Structure-property relationships of dissimilar friction stir welded aluminum alloys

    NASA Astrophysics Data System (ADS)

    Quinones, Rogie Irwin Rodriguez

    In this work, the relationship between microstructure and mechanical properties of dissimilar friction stir welded AA6061-to-AA7050 aluminum alloys were evaluated. Experimental results from this study revealed that static strength increased with the tool rotational speed and was correlated with the material intermixing. Fully-reversed low cycle fatigue experimental results showed an increase in the strain hardening properties as well as the number of cycles-to-failure as the tool rotational speed was increased. Furthermore, under both static and cyclic loading, fracture of the joint was dominated by the AA6061 alloy side of the weld. In addition, inspection of the fatigue surfaces revealed that cracks initiated from intermetallic particles located near the surface. In order to determine the corrosion resistance of the dissimilar joint, corrosion defects were produced on the crown surface of the weld by static immersion in 3.5% NaCl for various exposure times. Results revealed localized corrosion damage in the thermo-mechanically affected and heat affected zones. Results demonstrated a decrease in the fatigue life, with evidence of crack initiation at the corrosion defects; however, the fatigue life was nearly independent of the exposure time. This can be attributed to total fatigue life dominated by incubation time. Furthermore, two types of failure were observed: fatigue crack initiation in the AA6061 side at high strain amplitudes (>0.3%); and fatigue crack initiation in the AA7050 side at low strain amplitudes (<0.2%). Lastly, a microstructure-sensitive model based on a multi-stage fatigue damage concept was extended to the dissimilar friction stir welded joints in order to capture the crack initiation and propagation in as-welded and pre-corroded conditions. Good correlation between experimental fatigue results and the model was achieved based on the variation in the initial defect size, microstructure, and mechanical properties of the dissimilar friction stir

  3. Formability analysis of aluminum alloy sheets at elevated temperatures with numerical simulation based on the M-K method

    SciTech Connect

    Bagheriasl, Reza; Ghavam, Kamyar; Worswick, Michael

    2011-05-04

    The effect of temperature on formability of aluminum alloy sheet is studied by developing the Forming Limit Diagrams, FLD, for aluminum alloy 3000-series using the Marciniak and Kuczynski technique by numerical simulation. The numerical model is conducted in LS-DYNA and incorporates the Barlat's YLD2000 anisotropic yield function and the temperature dependant Bergstrom hardening law. Three different temperatures; room temperature, 250 deg. C and 300 deg. C, are studied. For each temperature case, various loading conditions are applied to the M-K defect model. The effect of the material anisotropy is considered by varying the defect angle. A simplified failure criterion is used to predict the onset of necking. Minor and major strains are obtained from the simulations and plotted for each temperature level. It is demonstrated that temperature improves the forming limit of aluminum 3000-series alloy sheet.

  4. Resistance Spot Welding of Aluminum Alloy to Steel with Transition Material - Part II: Finite Element Analyses of Nugget Growth

    SciTech Connect

    Sun, Xin; Khaleel, Mohammad A.

    2004-07-01

    This paper summarizes work on finite element modeling of nugget growth for resistance spot welding of aluminum alloy to steel. It is a sequel to a previous paper on experimental studies of resistance spot welding of aluminum to steel using a transition material. Since aluminum alloys and steel cannot be readily fusion welded together due to their drastically different thermal physical properties, a cold-rolled clad material was introduced as a transition to aid the resistance welding process. Coupled electrical-thermal-mechanical finite element analyses were performed to simulate the nugget growth and heat generation patterns during the welding process. The predicted nugget growth results were compared to the experimental weld cross sections. Reasonable comparisons of nugget size were achieved. The finite element simulation procedures were also used in the electrode selection state to help reduce weld expulsion and improve weld quality.

  5. A study of spectrum fatigue crack propagation in two aluminum alloys. I - Spectrum simplification. II - Influence of microstructures

    NASA Technical Reports Server (NTRS)

    Telesman, J.; Antolovich, S. D.

    1986-01-01

    An investigation of the fatigue crack propagation FCP behavior of two aluminum alloys is performed to simulate spectrum loading conditions found at critical locations in high performance fighter aircraft. Negative loads are shown to be eliminated for the tension-compression spectrum for low to intermediate maximum stress intensities, and load interactions are found to be more significant at higher stress intensities and with more plasticity at the crack tip. In the second part, the influence of microstructural features including grain size, inclusions, and dispersoids on constant amplitude and spectrum crack growth behavior in aluminum alloys is studied. At low stress intensities the I/M alloy demonstrated better FCP resistance than the P/M 7091 alloy for both constant amplitude and spectrum testing, and the inhomogeneous planar slip and large grain size of 7050 limit dislocation interactions, thereby improving FCP performance.

  6. Influence of Pre-straining and Heat Treatment on the Yield Surface of Precipitation Hardenable Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Lechner, Michael; Johannes, Maren; Kuppert, Andreas; Merklein, Marion

    Precipitation hardenable aluminum alloys are some of the most important lightweight materials. However, their range of applications in comparison to conventional deep drawing steels is limited by the low formability. Therefore, a new and innovative approach to enhance the formability of aluminum alloys in multistage forming operations was invented at the Institute of Manufacturing Technology, called intermediate heat treatment (IHT). Based on a short-term, laser-assisted heat treatment between two forming steps, it is possible to locally adapt the mechanical properties and realize an optimized strength distribution. For the successful application of the technology, the influence of the heat treatment on the mechanical properties has to be analyzed. Concerning the simulation of a multistage forming process, in particular, the yield surface of the material is very important. Within this paper, the influence of a combined pre-straining and a subsequent short-term, laser-assisted heat treatment on the yield surface will be presented.

  7. Avoidance of stress corrosion susceptibility in high strength aluminum alloys by control of grain boundary and matrix microstructure

    NASA Technical Reports Server (NTRS)

    Adler, P.; Deiasi, R.

    1974-01-01

    The relation of microstructure to the mechanical strength and stress corrosion resistance of highest strength and overaged tempers of BAR and 7050 aluminum alloys was investigated. Comparison is made with previously studied 7075 aluminum alloy. Optical microscopy, transmission electron microscopy, and differential scanning calorimetry were used to characterize the grain morphology, matrix microstructure, and grain boundary microstructure of these tempers. Grain boundary interparticle spacing was significant to stress corrosion crack propagation for all three alloys; increasing interparticle spacing led to increased resistance to crack propagation. In addition, the fire grain size in Bar and 7050 appears to enhance crack propagation. The highest strength temper of 7050 has a comparatively high resistance to crack initiation. Overall stress corrosion behavior is dependent on environment pH, and evaluation over a range of pH is recommended.

  8. Numerical Simulation and Experimental Characterization of a Binary Aluminum Alloy Spray - Application to the Spray Rolling Process

    SciTech Connect

    S. B. Johnson; J.-P. Delplanque; Y. Lin; Y. Zhou; E. J. Lavernia; K. M. McHugh

    2005-02-01

    A stochastic, droplet-resolved model has been developed to describe the behavior of a binary aluminum alloy spray during the spray-rolling process. In this process, a molten aluminum alloy is atomized and the resulting spray is depostied on the rolls of a twin-roll caster to produce aluminum strip. The one-way coupled spray model allows the prediction of spray characteristics such as enthalph and solid fraction, and their distribution between the nozzle and the depostion surface. This paper outlines the model development and compares the predicted spray dynamics to PDI measurements performed in a controlled configuration. Predicted and measured droplet velocity and size distributions are presented for two points along the spray centerline along with predicted spray averaged specific enthalph and solid fraction curves.

  9. A model for the formation of fatigue striations and its relationship with small fatigue crack growth in an aluminum alloy

    SciTech Connect

    Shyam, Amit; Lara-Curzio, Edgar

    2010-01-01

    The fatigue crack growth process involves damage accumulation and crack extension. The two sub-processes that lead to fatigue crack extension were quantified separately in a recent model for small fatigue crack growth applicable to engineering alloys. Here, we report the results of an experimental investigation to assess the assumptions of that model. The fatigue striation formation in an aluminum alloy is modeled and it is verified that the number of cycles required for striation formation is related to the cyclic crack tip opening displacement and that the striation spacing is related to the monotonic crack tip displacement. It is demonstrated that extensive cyclic crack tip plasticity in the aluminum alloy causes a reduction in the magnitude of the slope of the fatigue crack propagation curves. The implications of these results on the fatigue crack propagation lifetime calculations are identified.

  10. Diffraction-based study of fatigue crack initiation and propagation in aerospace aluminum alloys

    NASA Astrophysics Data System (ADS)

    Gupta, Vipul K.

    The crack initiation sites and microstructure-sensitive growth of small fatigue cracks are experimentally characterized in two precipitation-hardened aluminum alloys, 7075-T651 and 7050-T7451, stressed in ambient temperature moist-air (warm-humid) and -50°C dry N2 (cold-dry) environmental conditions. Backscattered electron imaging (BSE) and energy dispersive spectroscopy (EDS) of the fracture surfaces showed that Fe-Cu rich constituent particle clusters are the most common initiation sites within both alloys stressed in either environment. The crack growth within each alloy, on average, was observed to be slowed in the cold-dry environment than in the warm-humid environment, but only at longer crack lengths. Although no overwhelming effects of grain boundaries and grain orientations on small-crack growth were observed, crack growth data showed local fluctuations within individual grains. These observations are understood as crack propagation through the underlying substructure at the crack surface and frequent interaction with low/high-angle grain and subgrain boundaries, during cyclic loading, and, are further attributed to periodic changes in crack propagation path and multiple occurrences of crack-branching observed in the current study. SEM-based stereology in combination with electron backscattered diffraction (EBSD) established fatigue crack surface crystallography within the region from ˜1 to 50 mum of crack initiating particle clusters. Fatigue crack facets were parallel to a wide variety of crystallographic planes, with pole orientations distributed broadly across the irreducible stereographic triangle between the {001} and {101}-poles within both warm-humid and cold-dry environments. The results indicate environmentally affected fatigue cracking in both cases, given the similarity between the observed morphology and crystallography with that of a variety of aerospace aluminum alloys cracked in the presence of moist-air. There was no evidence of

  11. Processing and microstructural evolution of alumina/aluminum alloy and aluminum nitride/aluminum alloy composites by directed melt oxidation. Ph.D. Thesis

    SciTech Connect

    Crudele, S.D.

    1994-12-31

    An experimental investigation on the directed oxidation of aluminum-zinc alloys to produce alumina/aluminum alloy composites with and without alumina preforms has been conducted. It has been suggested in the literature that Al-Mg alloys grow composites by the dissolution of a magnesia surface layer and reprecipitation of alumina in the composite. The intent of this investigation is to reveal relevant distinctions in the proposed dissolution-reprecipitation process as they apply to a more commercially interesting Zn containing alloy with a reinforcing preform. The TGA behavior and microstructural observations on the oxidation of Al-10Zn-8Si alloys were coupled with a thermodynamic and kinetic analysis to develop a composite growth model. Experiments were carried out in air at 1000-1200 C. At the higher temperatures (greater than 1100 C), Al2O3/Al composites grow by dissolving a ZnAl2O4 (spinel) surface layer. The dissolution process releases oxygen that reprecipitates in the form of Al2O3 on the existing composite, and also releases Zn and Al which migrate upward through the spinel to regenerate the surface oxide. Composite growth may only occur when the surface regenerates at a rate comparable with that of the dissolution process. At the lower temperatures, 1000 C, the composite growth is limited by the spinel regeneration process, and becomes intermittent. The addition of Mg to this alloy allows normal composite growth by the dissolution of a surface (Zn,Mg)Al2O4 layer at the lower temperatures, 980-1060 C, but leads to heterogeneous microstructures with voids as the temperature increases above approximately 1060 C. The directed oxidation of an Al-Zn alloy into porous alumina preforms yields an Al2O3/Al composite matrix which fills the preform interstices. Al-10Zn-8Si-0.25Mg alloys that are oxidized from 960-1100 C, and Al-10Zn-8Si alloys that are oxidized at 800-1000 C climb up the preform particle.

  12. Laser peening without coating on aluminum alloy Al-6061-T6 using low energy Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Sathyajith, S.; Kalainathan, S.; Swaroop, S.

    2013-02-01

    The present study investigates the effect of laser peening without coating on aluminum alloy Al-6061-T6 with a 300 mJ infrared laser. The surface topography, microstructure, surface topography, surface residual stress and micro-hardness of peened and unpeened surfaces were studied. The study shows that laser peening without coating can significantly improve surface compressive stress and micro-hardness with trivial increase in surface roughness. Microstructure evaluation confirmed there was no near surface solidification after LPwC.

  13. Effect of hot and cold severe deformation by extrusion on the properties of lead and aluminum alloys

    NASA Astrophysics Data System (ADS)

    Ganiev, M. M.; Shibakov, V. G.; Pankratov, D. L.; Shibakov, R. V.

    2015-07-01

    The study of the effect of severe plastic deformation (SPD) by extrusion shows that the ductility of lead after several cycles of SPD increases significantly (3-4 times) as compared to as-cast samples. An aluminum alloy after this processing is hardened by a factor of 2.3-2.5, with ductility decreasing by 2.5-2.7 times, as compared to the as-delivered state.

  14. Corrosion Embrittlement of Duralumin II Accelerated Corrosion Tests and the Behavior of High-Strength Aluminum Alloys of Different Compositions

    NASA Technical Reports Server (NTRS)

    Rawdon, Henry S

    1928-01-01

    The permanence, with respect to corrosion, of light aluminum alloy sheets of the duralumin type, that is, heat-treatable alloys containing Cu, Mg, Mn, and Si is discussed. Alloys of this type are subject to surface corrosion and corrosion of the interior by intercrystalline paths. Results are given of accelerated corrosion tests, tensile tests, the effect on corrosion of various alloying elements and heat treatments, electrical resistance measurements, and X-ray examinations.

  15. Effect of Postweld Aging Treatment on Fatigue Behavior of Pulsed Current Welded AA7075 Aluminum Alloy Joints

    NASA Astrophysics Data System (ADS)

    Balasubramanian, V.; Ravisankar, V.; Madhusudhan Reddy, G.

    2008-04-01

    This article reports the effect of postweld aging treatment on fatigue behavior of pulsed current welded AA 7075 aluminum alloy joints. AA7075 aluminum alloy (Al-Zn-Mg-Cu alloy) has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to weight ratio, such as transportable bridge girders, military vehicles, road tankers, and railway transport systems. The preferred welding processes of AA7075 aluminum alloy are frequently gas tungsten arc welding (GTAW) process and gas metal arc welding (GMAW) process due to their comparatively easier applicability and better economy. Weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often results inferior weld mechanical properties and poor resistance to hot cracking. In this investigation, an attempt has been made to refine the fusion zone grains by applying pulsed current welding technique. Rolled plates of 10 mm thickness have been used as the base material for preparing multipass welded joints. Single V butt joint configuration has been prepared for joining the plates. The filler metal used for joining the plates is AA 5356 (Al-5Mg (wt.%)) grade aluminum alloy. Four different welding techniques have been used to fabricate the joints and they are: (i) continuous current GTAW (CCGTAW), (ii) pulsed current GTAW (PCGTAW), (iii) continuous current GMAW (CCGMAW), and (iv) pulsed current GMAW (PCGMAW) processes. Argon (99.99% pure) has been used as the shielding gas. Rotary bending fatigue testing machine has been used to evaluate fatigue behavior of the welded joints. Current pulsing leads to relatively finer and more equi-axed grain structure in GTA and GMA welds. Grain refinement is accompanied by an increase in fatigue life and endurance limit. Simple postweld aging treatment applied to the joints is found to be beneficial to enhance the fatigue performance of the welded joints.

  16. Crack growth behavior of 2219-T87 aluminum alloy from 20 K (-423 F) to 422 K (300 F)

    NASA Technical Reports Server (NTRS)

    Witzell, W. E.

    1973-01-01

    The aluminum alloy 2219-T87 has great potential for use as a cryogenic material for various manned and unmanned aerospace vehicles. Although its properties are generally known, toughness characteristics in various grain directions when the material is machined from thick plates and subjected to various environments have not been documented. This program, sponsored by the NASA Johnson Space Center, was designed to determine these properties between 20 K (-423 F) and 423 K (300 F).

  17. In-situ processing of aluminum nitride particle reinforced aluminum alloy composites

    NASA Astrophysics Data System (ADS)

    Zheng, Qingjun

    Discontinuously reinforced aluminum alloy composites (DRACs) have potential applications in automotive, electronic packaging, and recreation industries. Conventional processing of DRACs is by incorporation of ceramic particles/whiskers/fibers into matrix alloys. Because of the high cost of ceramic particles, DRACs are expensive. The goal of this work was to develop a low-cost route of AlN-Al DRACs processing through bubbling and reacting nitrogen and ammonia gases with aluminum alloy melt in the temperature range of 1373--1523 K. Thermodynamic analysis of AlN-Al alloy system was performed based on Gibbs energy minimization theory. AlN is stable in aluminum, Al-Mg, Al-Si, Al-Zn, and Al-Li alloys over the whole temperature range for application and processing of DRACs. Experiments were carried out to form AlN by bubbling nitrogen and ammonia gases through aluminum, Al-Mg, and Al-Si alloy melts. Products were characterized with XRD, SEM, and EDX. The results showed that in-situ processing of AlN reinforced DRACs is technically feasible. Significant AlN was synthesized by bubbling deoxidized nitrogen and ammonia gases. When nitrogen gas was used as the nitrogen precursor, the AlN particles formed in-situ are small in size, (<10 mum). The formation of AlN is strongly affected by the trace oxygen impurities in the nitrogen gas. The deleterious effect of oxygen impurities is due to their inhibition to the chemisorption of nitrogen gas at the interface. In comparison with nitrogen gas, bubbling ammonia led to formation of AlN particles in smaller size (about 2 mum or less) at a significantly higher rate. Ammonia is not stable and dissociated into nitrogen and hydrogen at reaction temperatures. The hydrogen functions as oxygen-getter at the interface and benefits chemisorption of nitrogen, thereby promoting the formation of AlN. The overall process of AlN formation was modeled using two-film model. For nitrogen bubbling gas, the whole process is controlled by chemisorption

  18. Multiscale Modeling of Damage Processes in Aluminum Alloys: Grain-Scale Mechanisms

    NASA Technical Reports Server (NTRS)

    Hochhalter, J. D.; Veilleux, M. G.; Bozek, J. E.; Glaessgen, E. H.; Ingraffea, A. R.

    2008-01-01

    This paper has two goals related to the development of a physically-grounded methodology for modeling the initial stages of fatigue crack growth in an aluminum alloy. The aluminum alloy, AA 7075-T651, is susceptible to fatigue cracking that nucleates from cracked second phase iron-bearing particles. Thus, the first goal of the paper is to validate an existing framework for the prediction of the conditions under which the particles crack. The observed statistics of particle cracking (defined as incubation for this alloy) must be accurately predicted to simulate the stochastic nature of microstructurally small fatigue crack (MSFC) formation. Also, only by simulating incubation of damage in a statistically accurate manner can subsequent stages of crack growth be accurately predicted. To maintain fidelity and computational efficiency, a filtering procedure was developed to eliminate particles that were unlikely to crack. The particle filter considers the distributions of particle sizes and shapes, grain texture, and the configuration of the surrounding grains. This filter helps substantially reduce the number of particles that need to be included in the microstructural models and forms the basis of the future work on the subsequent stages of MSFC, crack nucleation and microstructurally small crack propagation. A physics-based approach to simulating fracture should ultimately begin at nanometer length scale, in which atomistic simulation is used to predict the fundamental damage mechanisms of MSFC. These mechanisms include dislocation formation and interaction, interstitial void formation, and atomic diffusion. However, atomistic simulations quickly become computationally intractable as the system size increases, especially when directly linking to the already large microstructural models. Therefore, the second goal of this paper is to propose a method that will incorporate atomistic simulation and small-scale experimental characterization into the existing multiscale

  19. Intergranular corrosion in AA5XXX aluminum alloys with discontinuous precipitation at the grain boundaries

    NASA Astrophysics Data System (ADS)

    Bumiller, Elissa

    The US Navy currently uses AA5xxx aluminum alloys for structures exposed to a marine environment. These alloys demonstrate excellent corrosion resistance over other aluminum alloys (e.g., AA2xxx or AA7xxx) in this environment, filling a niche in the marine structures market when requiring a light-weight alternative to steel. However, these alloys are susceptible to localized corrosion; more specifically, intergranular corrosion (IGC) is of concern. IGC of AA5xxx alloys due to the precipitation of beta phase on the grain boundaries is a well-established phenomenon referred to as sensitization. At high degrees of sensitization, the IGC path is a continuous anodic path of beta phase particles. At lower degrees of sensitization, the beta phase coverage at the grain boundaries is not continuous. The traditional ranges of susceptibility to IGC as defined by ASTM B928 are in question due to recent studies. These studies showed that even at mid range degrees of sensitization where the beta phase is no longer continuous, IGC may still occur. Previous thoughts on IGC of these alloy systems were founded on the idea that once the grain boundary precipitate became discontinuous the susceptibility to IGC was greatly reduced. Additionally, IGC susceptibility has been defined metallurgically by compositional gradients at the grain boundaries. However, AA5xxx alloys show no compositional gradients at the grain boundaries, yet are still susceptible to IGC. The goal of this work is to establish criteria necessary for IGC to occur given no continuous beta phase path and no compositional gradient at the grain boundaries. IGC performance of the bulk alloy system AA5083 has been studied along with the primary phases present in the IGC system: alpha and beta phases using electrochemistry and modeling as the primary tools. Numerical modeling supports that at steady-state the fissure tip is likely saturated with Mg in excess of the 4% dissolved in the matrix. By combining these results

  20. Corrosion resistance and durability of siloxane ceramic/polymer films for aluminum alloys in marine environments

    NASA Astrophysics Data System (ADS)

    Kusada, Kentaro

    The objective of this study is to evaluate corrosion resistance and durability of siloxane ceramic/polymer films for aluminum alloys in marine environments. Al5052-H3 and Al6061-T6 were selected as substrates, and HCLCoat11 and HCLCoat13 developed in the Hawaii Corrosion Laboratory were selected for the siloxane ceramic/polymer coatings. The HCLCoat11 is a quasi-ceramic coating that has little to no hydrocarbons in its structure. The HCLCoat13 is formulated to incorporate more hydrocarbons to improve adhesion to substrate surfaces with less active functionalities. In this study, two major corrosion evaluation methods were used, which were the polarization test and the immersion test. The polarization tests provided theoretical corrosion rates (mg/dm 2/day) of bare, HCLCoat11-coated, and HCLCoat13-coated aluminum alloys in aerated 3.15wt% sodium chloride solution. From these results, the HCLCoat13-coated Al5052-H3 was found to have the lowest corrosion rate which was 0.073mdd. The next lowest corrosion rate was 0.166mdd of the HCLCoat11-coated Al5052-H3. Corrosion initiation was found to occur at preexisting breaches (pores) in the films by optical microscopy and SEM analysis. The HCLCoat11 film had many preexisting breaches of 1-2microm in diameter, while the HCLCoat13 film had much fewer preexisting breaches of less than 1microm in diameter. However, the immersion tests showed that the seawater immersion made HCLCoat13 film break away while the HCLCoat11 film did not apparently degrade, indicating that the HCLCoat11 film is more durable against seawater than the HCLCoat13. Raman spectroscopy revealed that there was some degradation of HCLCoat11 and HCLCoat13. For the HCLCoat11 film, the structure relaxation of Si-O-Si linkages was observed. On the other hand, seawater generated C-H-S bonds in the HCLCoat13 film resulting in the degradation of the film. In addition, it was found that the HCLCoat11 coating had anti-fouling properties due to its high water contact

  1. Preparation and anti-icing behavior of superhydrophobic surfaces on aluminum alloy substrates.

    PubMed

    Ruan, Min; Li, Wen; Wang, Baoshan; Deng, Binwei; Ma, Fumin; Yu, Zhanlong

    2013-07-01

    It has been expected that superhydrophobic (SHP) surfaces could have potential anti-icing applications due to their excellent water-repellence properties. However, a thorough understanding on the anti-icing performance of such surfaces has never been reported; even systematic characterizations on icing behavior of various surfaces are still rare because of the lack of powerful instrumentations. In this study, we employed the electrochemical anodic oxidation and chemical etching methods to simplify the fabrication procedures for SHP surfaces on the aluminum alloy substrates, aiming at the anti-icing properties of SHP surfaces of various engineering materials. We found that the one-step chemical etching with FeCl3 and HCl as the etchants was the most effective for ideal SHP surfaces with a large contact angle (CA, 159.1°) and a small contact angle hysteresis (CAH, 4.0°). To systematically investigate the anti-icing behavior of the prepared SHP surfaces, we designed a robust apparatus with a real-time control system based on the two stage refrigerating method. This system can monitor the humidity, pressure, and temperature during the icing process on the surfaces. We demonstrated that the SHP surfaces exhibited excellent anti-icing properties, i.e., from the room temperature of 16.0 °C, the icing time on SHP surfaces can be postponed from 406s to 676s compared to the normal aluminum alloy surface if the surfaces were put horizontally, and the icing temperature can be decreased from -2.2 °C to -6.1 °C. If such surfaces were tilted, the sprayed water droplets on the normal surfaces iced up at the temperature of -3.9 °C, but bounced off the SHP surface even as the temperature reached as low as -8.0 °C. The present study therefore suggests a general, simple, and low-cost methodology for the promising anti-icing applications in various engineering materials and different fields (e.g., power lines and aircrafts). PMID:23718719

  2. Modeling of porosity formation and feeding flow during casting of steel and aluminum alloys

    NASA Astrophysics Data System (ADS)

    Lin, Zhiping

    Porosity is one of the most important defects in metal casting. To quantitatively predict the porosity formation during casting two numerical models are developed for steel and aluminum alloys respectively. For steel, a multi-phase model is developed that predicts melt pressure, feeding flow, porosity (both microscopic and macroscopic), and riser pipe formation during casting. The phases included in the model are solid, liquid, porosity, and air. An energy equation is solved to determine solid fraction. A multi-phase momentum equation, which is valid everywhere in the solution domain, is derived. A pressure equation is then derived from this momentum equation and a mixture continuity equation developed that accounts for all phases. The partial pressure of a gas species dissolved in the melt is determined using the species concentration, which is found by solving a species conservation equation that accounts for convection. Porosity forms once the gas pressure exceeds the sum of the melt pressure and the capillary pressure. The amount of porosity that forms is determined from the mixture continuity equation. The riser pipe is determined from an air continuity equation. A pore size model, which considers the effects of the solidifying steel microstructure on pore size, is incorporated into the multi-phase model. The multi-phase model is applied to one-dimensional, two-dimensional, and three-dimensional simulations. The results clearly illustrate the basic physical phenomena involved and predict microporosity and macroporosity distributions, as well as a riser pipe. For aluminum alloys a gas microsegregation model is developed to quantitatively predict porosity, coupled with the calculations of the pressure field, feeding flow, and distribution of dissolved gas species throughout the casting. The effects of dendritic and eutectic microstructure on the pore shape and size are considered in a pore size model. The model is applied to one-dimensional simulations of A319

  3. Friction Stir Welding of Age-Hardenable Aluminum Alloys: A Parametric Approach Using RSM Based GRA Coupled With PCA

    NASA Astrophysics Data System (ADS)

    Vijayan, D.; Rao, V. S.

    2014-04-01

    Age-hardenable aluminum alloys, primarily used in the aerospace, automobile and marine industries (2×××, 6××× and 7×××), can be welded using solid-state welding techniques. Friction stir welding is an emerging solid-state welding technique used to join both similar and dissimilar materials. The strength of a friction stir welded joint depends on the joining process parameters. Therefore, a combination of the statistical techniques of a response surface methodology based on a grey relational analysis coupled to a principal component analysis was proposed to select the process parameters suitable for joining AA 2024 and AA 6061 aluminum alloys via friction stir welding. The significant process parameters, such as rotational speed, welding speed, axial load and pin shapes (PS) were considered during the statistical experiment. The results indicate that the square PS plays a vital role and yields an ultimate tensile strength of 141 MPa for an elongation of 12 % versus cylinder and taper pin profiles. The root cause for joint strength loss and fracture mode was analyzed using scanning electron microscopy. Severe material flow during macro defects, such as pin holes and porosity, degrades the joint strength by approximately 44 % for AA 2024 and 51 % for AA 6061 fabricated FS-welded aluminum alloys relative to the base material. The results of this approach are useful for accurately controlling the response and optimize the process parameters.

  4. An optimizing process of profiled cross-sectional aluminum alloy porthole die extrusion using response surface methodology

    NASA Astrophysics Data System (ADS)

    Zhou, Fujian; Li, Feng; Shi, Liansheng; Jiang, Hongwei

    2016-03-01

    The porthole die extrusion process of profiled cross-section hollow aluminum alloy is influenced by numerous factors, which brings inconvenience to the process design. In this paper, 7075 aluminum alloy is taken as an example, the fitting model of the ultimate load is analyzed by variance and regression analysis using response surface method (RSM). The influences of extrusion speed, friction factor and initial temperature on the change of extruded ultimate load are investigated systematically, and the important influence factors (initial temperature > friction factor > extrusion speed) to the load are determined eventually. By comparison, the error between the ultimate load model obtained after fitting and the calculated value is only 2.4%, further verifying the reliability of this model. The optimal objective is to minimize the ultimate load, then the optimum technological parameters are obtained by optimizing the process, where the initial temperature, the extrusion speed and the friction factor are 430∘C, 2.28mm/s and 0.31, respectively. The results provide a theoretical basis for the scientific design of the porthole die extrusion process of profiled cross-section hollow aluminum alloy.

  5. Fatigue behavior of 6063 aluminum alloy extrusions for wind-turbine applications

    SciTech Connect

    Warren, A.S.

    1990-01-01

    The fatigue behavior of a 6063 aluminum alloy used in the Vertical Axis Wind Turbine (VAWT) blade extrusions was investigated under a variety of cyclic loading conditions and with different specimen geometries in order to examine the mechanisms of fatigue crack initiation and crack growth, and to provide fatigue data for use in life prediction models. The effect of open holes on fatigue crack initiation and crack growth, and on the S-N curves were investigated with plate bending. Fatigue life in plane bending was controlled by crack propagation. Hole preparation by drilling, or drilling and reaming were found to produce equivalent crack initiation behavior, and overall fatigue lives. Fatigue crack growth rates, including near-threshold behavior, were measured under LEFM conditions with compact tension specimens as a function of: heat treatment, crack plane orientation with respect to the extrusion direction, and R ratio. Low-cycle fatigue behavior and cyclic material properties were examined, and compared on the basis of material condition for extruded VAWT blade material, re-heat treated blade material and commercial 6063-T5 extruded rod. Low cyclic ductility values were observed in the extruded blade material.

  6. Nonchemical surface treatment for aluminum alloys. Final report, 1 April--1 September 1996

    SciTech Connect

    Koch, G.H.; Todd, G.L.; Deutchman, A.; Partyka, R.

    1996-09-01

    The state-of-the-art chemical surface treatments for adhesive bonding of aluminum alloys, such as phosphoric acid anodizing (PAA) are the basis of the present high-strength and durable adhesive bonds. Because of increasingly strict regulations on the use of wet chemicals, the Materials Directorate at Wright Laboratories initiated a research program to develop alternative nonchemical techniques that do not produce waste and are not detrimental to health and environment. This report describes the development of a nonchemical process, based on ion beam enhanced deposition (IBED). The process consists of various steps, the major ones being grit blasting with 50 micrometers Al{sub 2}O{sub 3} grit and deposition of (proportional to)-Al{sub 2}O{sub 3} with IBED. The resulting surface is dense and corrosion resistant, and provides an excellent basis for adhesive bonding. Strength and durability studies on peel and wedge type specimens is equivalent to that of anodized specimens. Surface analytical studies, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR) , and Atomic Force Microscopy (AFM), as well as electrochemical studies were used to characterize the surface and determine the mechanism of adhesion.

  7. Electrochemical characterization and occluded environment analysis of localized corrosion in advanced aluminum alloys

    SciTech Connect

    Wall, F.D.; Stoner, G.E.

    1994-12-31

    In order for advanced aluminum alloys to be used in structural applications it is necessary to understand and mitigate failures that can occur due to localized corrosion events. Mechanical and electrochemical stresses interacting with a microstructural heterogeneity can result in the rapid growth of a flaw in the material; this phenomenon is a form of environmentally assisted cracking (EAC). One possible mechanism of EAC in Al-Li-X alloys is the preferential dissolution of an electrochemically active microstructural feature along a grain or sub-grain boundary. To examine this mechanism it is necessary to obtain information on the occluded environment that develops in a growing crack and the electrochemical behavior of boundary phases in the occluded environment. The electrochemistry of three relevant boundary phases (matrix phase (SHT 2095), T{sub 1} precipitate (Al{sub 2}CuLi) and Cu-depleted zone (99.99% Al)) in several model environments has been documented using a variety of electrochemical techniques including scratching and straining electrode experiments. The electrochemical behavior of these phases has been linked to the SCC behavior of several Al-Li-X alloys using constant load testing under applied potentials in NaCl/Li{sub 2}CO{sub 3} and NaCl/Na{sub 2}CrO{sub 4} environments. The occluded environment model is being evaluated and refined by analysis of occluded chemistries using pH measurements and capillary electrophoresis.

  8. Mathematical modeling and experimental validation of gas metal arc welding of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Guo, Hao

    2004-11-01

    Both mathematical modeling and experiments have been conducted on the GMAW of aluminum alloys. Transient weld shapes and distributions of temperature and velocity were calculated by a three-dimensional numerical model. The final weld bead shape and dimensions and peak temperature in the heat-affected zone (HAZ) were obtained. Metallurgical characterizations including microscopy and Knoop micro-hardness measurements were performed on experimental samples. The experimental weld bead shape and dimensions were in agreement with modeling predictions. It was found that a crater-shaped weld pool was formed as a result of weld pool dynamics. The combined effect of a series of droplet impingements and hydrostatic force caused the fluid level at the rear end of weld pool to vary periodically to form ripples on the weld bead. Also, the high peak temperature near the fusion line caused the HAZ softening. The lack of penetration in the cold weld is due to the lack of pre-heating by the welding arc. Three techniques were then proposed to increase the energy input at the initial stage of welding and improve cold weld penetration. The crater formation at the end of the welding process is due to the rapid solidification of the weld pool. The crater was filled and crater cracking was reduced by reducing welding current and reversing the welding direction at the same time before terminating the arc.

  9. Use of Permanent Magnets in Electromagnetic Facilities for the Treatment of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Beinerts, Toms; Bojarevičs, Andris; Bucenieks, Imants; Gelfgat, Yuri; Kaldre, Imants

    2016-06-01

    The possibility of applying the electromagnetic induction pump with permanent magnets for the transportation and stirring of aluminum melts in metallurgical furnaces is investigated. The electromagnetic and hydraulic characteristics of the pump have been investigated theoretically and experimentally with regard to its position in the furnace. The results of the experiments performed with a model in a eutectic InGaSn melt are in good agreement with the calculation data. Extrapolation of the experimental results on the physical characteristics of aluminum melts allows recommending such pumps for contactless control of motion and heat/mass transfer in aluminum melts in different technological processes. A high temperature and the aggressive properties of aluminum alloys make it complicated to use different mechanical devices to solve technological problems, such as liquid metal transportation, dosing, stirring, etc. In this case, any device units or elements moving in or contacting with the melt suffer from corrosion polluting the melt. Therefore, of more importance and topicality are contactless electromagnetic methods for processing of molten metals.

  10. Computer-assisted Rheo-forging Processing of A356 Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Kim, H. H.; Kang, C. G.

    2010-06-01

    Die casting process has been used widely for complex automotive products such as the knuckle, arm and etc. Generally, a part fabricated by casting has limited strength due to manufacturing defects by origin such as the dendrite structure and segregation. As an attempt to offer a solution to these problems, forging has been used as an alternative process. However, the forging process provides limited formability for complex shape products. Rheo-forging of metal offers not only superior mechanical strength but also requires significantly lower machine loads than solid forming processes. In order to produce semi-solid materials of the desired microstructure, a stirring process is applied during solidification of A356 aluminum molten state. This paper presents the results of an A356 aluminum alloy sample, which were obtained by experiment and by simulation using DEFORM 3D V6.1. Samples of metal parts were subsequently fabricated by using hydraulic press machinery. In order to compare the influence of loading method, two types of samples were fabricated: (1) samples fabricated under direct loading die sets (2) those fabricated under indirect loading die sets. The formability and defects, which were predicted by FEM simulation, were similar to those of samples used in practice.

  11. The influence of crack closure on fatigue crack growth thresholds in 2024-T3 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Phillips, Edward P.

    1988-01-01

    Crack opening loads were determined in load-shedding fatigue crack growth threshold tests on 2024-T3 aluminum alloy at stress ratios R of -2, -1, 0, 0.33, 0.5, and 0.7. The effects of load-shedding procedure and rate were investigated. Values of threshold Delta-K were found to vary significantly with R, whereas values of threshold effective Delta-K did not. That is, the variation of threshold Delta-K with R was almost completely explained by accounting for the measured variation in crack opening load behavior with R. The load-shedding guidelines of ASTM Test Method for Measurement of Fatigue Crack Growth (E 647) produced a threshold Delta-K value for R = 0.7 that was in agreement with the value determined using a procedure that should minimize closure effects. At both R = 0 and R = 0.7, high load-shedding rates produced high values of threshold Delta-K caused by large closure effects.

  12. Measurement and analysis of critical CTOA for an aluminum alloy sheet

    NASA Technical Reports Server (NTRS)

    Dawicke, D. S.; Sutton, M. A.; Newman, J. C., Jr.; Bigelow, C. A.

    1993-01-01

    The stable tearing behavior of thin sheets of 2024-T3 aluminum alloy was investigated for middle crack tension, M(T), and compact tension, C(T), specimens. The surface crack-tip opening angle (CTOA), applied loads, crack extension, and local displacements were measured. A critical CTOA fracture criterion was incorporated into a two-dimensional, elastic plastic finite element code and used to simulate the experimental fracture behavior. The CTOA measurements and observations of the fracture surfaces have shown that large values for surface CTOA were observed for small crack extensions (less than the sheet thickness); substantial tunneling of the crack was associated with small crack extensions; crack tunneling in the M(T) specimen was less than that observed in the C(T) configuration; for larger crack extensions, the measured CTOA values were determined to be approximately 6 degrees for both the M(T) and C(T) configuration; and for larger crack extensions, crack tunneling remained constant. The two-dimensional finite element predictions of fracture behavior assumed a constant critical CTOA value of 6 degrees and accounted for local crack tip constraint with a plane strain core of elements ahead of the crack tip. The plane strain core extended 5 mm above the crack plane. The simulations were within +/- 4 percent of the maximum applied load for the C(T) tests within 2 percent for the M(T) tests.

  13. The effect of thickness on fatigue crack propagation in 7475-T731 aluminum alloy sheet

    NASA Technical Reports Server (NTRS)

    Daiuto, R. A.; Hillberry, B. M.

    1984-01-01

    Tests were conducted on three thicknesses of 7475-T731 aluminum alloy sheet to investigate the effect of thickness on fatigue crack propagation under constant amplitude loading conditions and on retardation following a single peak overload. Constant amplitude loading tests were performed at stress ratios of 0.05 and 0.75 to obtain data for conditions with crack closure and without crack closure, respectively. At both stress ratios a thickness effect was clearly evident, with thicker specimens exhibiting higher growth rates in the transition from plane strain to plane stress region. The effect of thickness for a stress ratio of 0.05 corresponded well with the fracturing mode transitions observed on the specimens. A model based on the strain energy release rate which accounted for the fracture mode transition was found to correlate the thickness effects well. The specimens tested at the stress ratio of 0.75 did not make the transition from tensile mode to shear mode, indicating that another mechanism besides crack closure or fracture mode transition was active.

  14. Compressive strength, plastic flow properties, and surface frictional effects of 1100, 3003 and 6061 aluminum alloys

    SciTech Connect

    Pinkerton, G.W.

    1993-12-31

    The purpose of this study is to find aluminum alloys that are effective for use as wire vacuum seals in the 800MeV particle accelerator located at the Louis Anderson Meson Physics Facility (LAMPF) in Los Alamos, NM. Three alloys, Al 1100, Al 3003, and Al 6061, are investigated under uniaxial compression to determine stresses for a given height reduction from 0 to 70 percent, and to find plastic flow and surface interaction effects. Right-circular cylindrical specimens are compressed on-end (cylindrically) and radially (for modeling as compressed wire). Aluminum 1100 and 3003 alloys are compared for length to diameter ratios of 1 and 2 for both compression types, and are then compared to results of radial compression of annealed small diameter Al 1100 wire currently used at LAMPE. The specimens are also compressed between three different platen surfaces, polished steel, etched steel, and aluminum 6061-T6, to determine effects of friction. The Al 3003 alloy exhibits 20 to 25% lower stresses at all height reductions than Al 1100 for both cylindrical and radial compression.

  15. Two-Phase Modeling of Hot Tearing in Aluminum Alloys: Applications of a Semicoupled Method

    NASA Astrophysics Data System (ADS)

    Mathier, V.; Vernède, S.; Jarry, P.; Rappaz, M.

    2009-04-01

    Hot tearing formation in both a classical tensile test and during direct chill (DC) casting of aluminum alloys has been modeled using a semicoupled, two-phase approach. Following a thermal calculation, the deformation of the mushy solid is computed using a compressive rheological model that neglects the pressure of the intergranular liquid. The nonzero expansion/compression of the solid and the solidification shrinkage are then introduced as source terms for the calculation of the pressure drop and pore formation in the liquid phase. A comparison between the simulation results and experimental data permits a detailed understanding of the specific conditions under which hot tears form under given conditions. It is shown that the failure modes can be quite different for these two experiments and that, as a consequence, the appropriate hot tearing criterion may differ. It is foreseen that a fully predictive theoretical tool could be obtained by coupling such a model with a granular approach. These two techniques do, indeed, permit coverage of the range of the length scales and the physical phenomena involved in hot tearing.

  16. Modeling Macrosegregation during Direct-Chill Casting of Multicomponent Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Du, Q.; Eskin, D. G.; Katgerman, L.

    2007-01-01

    A macrosegregation model for direct chill casting of multicomponent aluminum alloys is implemented using the macroscopic transfer model, microsegregation model, and phase diagram calculation module, and applied to an Al-Cu-Mg alloy. The phase diagram calculation module is based on the TQ-Interface of CALPHAD software THERMO-CALC and the mapping technique initially proposed by Dore et al. This mapping technique is modified in arranging the mapping axes where the tabulation is performed to increase the access efficiency. This strategy provides a practical solution for quick access to phase diagram data in modeling macrosegregation of multicomponent alloys. It is found from our simulation that the contribution of each of the solute elements to the solutal buoyancy affects the final segregation pattern. The appropriate choice of the solidification path is important for the shrinkage-induced macrosegregation. The model is applied to a real direct-chill (DC) casting experiment and a reasonable semiquantitative agreement with experimental data has been obtained, though the model does not take into account the possible contribution of floating grains and exudation.

  17. Structural Homogeneity of Direct-Chill Cast Ingots of Aluminum Alloy EN AW-5083

    NASA Astrophysics Data System (ADS)

    Dolić, Natalija; Markotić, Ante; Unkić, Faruk

    2007-06-01

    Structural homogeneity of direct-chill (DC) cast ingots of aluminum alloy EN AW-5083 was investigated in terms of grain size and grain distribution using the Latin square experimental design. The ingot cross-sectional homogeneity, the grain sizes, and the mean grain number per unit area were determined at precise, statistically defined locations in the slice by means of a semiautomatic method for measuring mean lineal intercept lengths. Based on the analysis of the differences in the number and distribution of grains between the slices cut from the ingot front and those from its rear, a general assessment of the ingot structural homogeneity was made. Analysis of variance showed the highly significant differences, in grain number in specimens taken from the ingot front section to be related to slice height/ingot depth and in those taken from the ingot rear section to individual charges and slice height. The grand means of the mean number of grains per unit area for the ingot front and rear sections show relatively high values with respect to ingot size. The obtained correlation coefficient, which suggests a good agreement between the number and distribution of grains at the ingot front and those at its rear, is indicative of good structural homogeneity of the ingot in general.

  18. The use of water cooling during the continuous casting of steel and aluminum alloys

    NASA Astrophysics Data System (ADS)

    Sengupta, J.; Thomas, B. G.; Wells, M. A.

    2005-01-01

    In both continuous casting of steel slabs and direct chill (DC) casting of aluminum alloy ingots, water is used to cool the mold in the initial stages of solidification, and then below the mold, where it is in direct contact with the newly solidified surface of the metal. Water cooling affects the product quality by (1) controlling the heat removal rate that creates and cools the solid shell and (2) generating thermal stresses and strains inside the solidified metal. This work reviews the current state-of-the-art in water cooling for both processes, and draws insights by comparing and contrasting the different practices used in each process. The heat extraction coefficient during secondary cooling depends greatly on the surface temperature of the ingot, as represented by boiling water-cooling curves. Thus, the heat extraction rate varies dramatically with time, as the slab/ingot surface temperature changes. Sudden fluctuations in the temperature gradients within the solidifying metal cause thermal stresses, which often lead to cracks, especially near the solidification front, where even small tensile stresses can form hot tears. Hence, a tight control of spray cooling for steel, and practices such as CO2 injection/pulse water cooling for aluminum, are now used to avoid sudden changes in the strand surface temperature. The goal in each process is to match the rate of heat removal at the surface with the internal supply of latent and sensible heat, in order to lower the metal surface temperature monotonically, until cooling is complete.

  19. Micromechanical modeling of temperature-dependent initiation fracture toughness in advanced aluminum alloys

    SciTech Connect

    Haynes, M.J.; Somerday, B.P.; Gangloff, R.P.; Lach, C.L.

    1997-12-31

    The temperature dependence of the plane-strain initiation fracture toughness (K{sub JICi}) is modeled micromechanically for a variety of advanced aluminum alloys that fail by microvoid processes. Materials include precipitation-hardened ingot metallurgy, spray formed, submicron-grain-size powder metallurgy, and metal-matrix composite alloys. A critical-plastic-strain-controlled model, employing tensile yield strength, elastic modulus, work hardening, and reduction of area measurements, successfully predicts K{sub JICi} versus temperature for eight alloys, providing a strong confirmation of this approach. Modeling shows that K{sub JICi} is controlled by the interplay between the temperature dependencies of the intrinsic failure locus {bar {var_epsilon}}{sub f}{sup p}({sigma}{sub m}/{sigma}{sub fl}) and the crack-tip stress/strain fields governed by alloy flow properties. Uncertainties in {bar {var_epsilon}}{sub f}{sup p}({sigma}{sub m}/{sigma}{sub fl}), as well as the critical distance (volume) for crack-tip damage evolution, hinder absolute predictions of K{sub JICi}. Critical distance (calculated from the model) correlates with the nearest-neighbor spacing of void-nucleating particles and with the extent of primary void growth determined from quantitative fractography. These correlations suggest a means to predict absolute plane-strain fracture toughness.

  20. A microscopic study of crack initiation mechanisms in 7075 aluminum alloy sheets.

    NASA Technical Reports Server (NTRS)

    Jones, D. L.; Liebowitz, H.

    1973-01-01

    A study of the opening mode of crack initiation in 7075-T6 aluminum alloy sheets has been conducted with the aid of a scanning electron microscope. Observations were made from several orientations, including the top view of the specimen which showed the notch profile and the edge view of the specimen which showed the entire notch front along the specimen thickness. It was found that the edge view exhibited the first signs of permanent deformation at about 55% of the breaking strength. These changes took the form of deformation bands which were aligned in the direction of the tensile axis and apparently defined limiting regions of homogeneous slip. It is felt that the appearance of microcracks at loads approaching the breaking strength was of fundamental importance in the formation of the final fracture surface. Many of these microcraks were initiated at intermetallic particles and other metallurgically weak regions on the notch surface. It was also possible to correlate the strain in the notch with the stress intensity factor for the various loads. Very large plastic strains were observed on the notch tip as compared to published values of elongation at fracture for unnotched specimens.

  1. Crystallization behavior of iron-containing intermetallic compounds in 319 aluminum alloy

    SciTech Connect

    Narayanan, L.A.; Samuel, F.H. ); Gruzleski, J.E. . Dept. of Mining and Metallurgical Engineering)

    1994-08-01

    The crystallization behavior of iron-containing intermetallic compounds in industrial grade 319 aluminum alloy has been investigated by means of thermal analysis and metallography. In the absence of manganese, the iron compound crystallizes in the [beta] phase, at all cooling rates ranging from 0.1 C/s to 20 C/s under normal casting temperatures (750 C). However, when the melt is superheated to a high temperature (about 200 to 300 degrees above the liquidus temperature), the iron compound crystallizes in the [alpha] phase at high cooling rates. This is due to the fact that [gamma] alumina, which forms at low melt temperatures ([<=]750 C), acts as a nucleus for crystallization of [beta] phase. When the melt is superheated to high temperatures ([>=] 850 C), the [gamma] alumina transforms to [alpha] alumina. This is a poor nucleus for the [beta]-phase crystallization, and as a result, [alpha] phase forms. The importance of nucleation and growth undercooling for the crystallization of iron compounds is highlighted. In the presence of manganese, the iron compound crystallizes in [alpha] phase at low cooling rates and in both the [alpha] and [beta] phases at high cooling rates. This reverse crystallization behavior is explained in terms of phase diagram relationships.

  2. Microstructure Analysis on 6061 Aluminum Alloy after Casting and Diffuses Annealing Process

    NASA Astrophysics Data System (ADS)

    Wang, H. Q.; Sun, W. L.; Xing, Y. Q.

    One factory using semi-continuous casting process produce the ф200×6000 mm 6061 aluminium alloy barstock, and then rotary forged for car wheels. 6061 distorting aluminium alloy is an forged aluminum alloy, and mainly containing Mg, Si, Cu and other alloying elements. The main strengthening phase is Mg2Si, and also has few phase of (FeMn) 3Si2Al15. In order to eliminate the segregation and separation which present in the crystal boundary, and make the distortion to be uniform, and does not present ear and fracture defects after the forging. So the 6061 distorting aluminium alloy adopt the diffusion annealing heat treatment before the forging process.According to the current conditions, we use the diffusion annealing which have the different heating temperature and different holding time.The best process we can obtain from the test which can improve the production efficiency and reduce the material waste, improve the mechanical properties, and eliminate the overheated film on the surface.Then,we using OM,SEM and EDS to analyse the microstructure and the chemical composition of compound between the surface and centre. The result shows that the amount of segregation were different in the surface and in the center, and the different diffusion annealing can cause the phase change in the surface and the center.

  3. Microstructure characterization of the stir zone of submerged friction stir processed aluminum alloy 2219

    SciTech Connect

    Feng, Xiuli; Liu, Huijie; Lippold, John C.

    2013-08-15

    Aluminum alloy 2219-T6 was friction stir processed using a novel submerged processing technique to facilitate cooling. Processing was conducted at a constant tool traverse speed of 200 mm/min and spindle rotation speeds in the range from 600 to 800 rpm. The microstructural characteristics of the base metal and processed zone, including grain structure and precipitation behavior, were studied using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Microhardness maps were constructed on polished cross sections of as-processed samples. The effect of tool rotation speed on the microstructure and hardness of the stir zone was investigated. The average grain size of the stir zone was much smaller than that of the base metal, but the hardness was also lower due to the formation of equilibrium θ precipitates from the base metal θ′ precipitates. Stir zone hardness was found to decrease with increasing rotation speed (heat input). The effect of processing conditions on strength (hardness) was rationalized based on the competition between grain refinement strengthening and softening due to precipitate overaging. - Highlights: • SZ grain size (∼ 1 μm) is reduced by over one order of magnitude relative to the BM. • Hardness in the SZ is lower than that of the precipitation strengthened BM. • Metastable θ′ in the base metal transforms to equilibrium θ in the stir zone. • Softening in the SZ results from a decrease of precipitation strengthening.

  4. Use of Permanent Magnets in Electromagnetic Facilities for the Treatment of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Beinerts, Toms; Bojarevičs, Andris; Bucenieks, Imants; Gelfgat, Yuri; Kaldre, Imants

    2016-03-01

    The possibility of applying the electromagnetic induction pump with permanent magnets for the transportation and stirring of aluminum melts in metallurgical furnaces is investigated. The electromagnetic and hydraulic characteristics of the pump have been investigated theoretically and experimentally with regard to its position in the furnace. The results of the experiments performed with a model in a eutectic InGaSn melt are in good agreement with the calculation data. Extrapolation of the experimental results on the physical characteristics of aluminum melts allows recommending such pumps for contactless control of motion and heat/mass transfer in aluminum melts in different technological processes. A high temperature and the aggressive properties of aluminum alloys make it complicated to use different mechanical devices to solve technological problems, such as liquid metal transportation, dosing, stirring, etc. In this case, any device units or elements moving in or contacting with the melt suffer from corrosion polluting the melt. Therefore, of more importance and topicality are contactless electromagnetic methods for processing of molten metals.

  5. Effect of Preheating in Hybrid Friction Stir Welding of Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Yaduwanshi, D. K.; Bag, S.; Pal, S.

    2014-10-01

    The controlled energy input into the system by introducing an extra heat source to enhance the material flow along with reduction of the plunging force remains a potential area of considerate for the development of hybrid friction stir welding (FSW) process. Hence, the effect of preheating on the weld joint properties is evaluated using plasma-assisted friction stir welding (P-FSW) process for joining aluminum alloy. A comparative study of mechanical and macro-microstructural characterizations of weld joint by FSW and P-FSW has been performed. Transverse tensile strength of weld joint is approximately 95% of base metal produced by P-FSW and is 8% more than conventional FSW welds. The effect of preheating enhances material flow and dissolution of fine oxide particles by plasma arc results in increase of strength and marginal modification of deformation behavior. The preheating brings uniformly distributed hardness in weld zone and the magnitude is higher in the advancing side with overall increase in average hardness value. Grain sizes are much finer due to the pinning effect of Al2O3 particles that retarded grain growth following recrystallization during P-FSW and thus led to more pronounced reduction in grain size and relatively brittle fracture during tensile loading of welded joint. Overall, the influence of preheating acts quite homogeneously throughout the structure as compared to conventional FSW. However, the results reveal that the development of P-FSW is still in initial stage and needs to improve in various aspects.

  6. Laser-assisted friction stir welding of aluminum alloy lap joints: microstructural and microhardness characterizations

    NASA Astrophysics Data System (ADS)

    Casalino, Giuseppe; Campanelli, Sabina L.; Contuzzi, Nicola; Angelastro, Andrea; Ludovico, Antonio D.

    2014-02-01

    Friction Stir Welding (FSW) is a solid-state joining process; i.e., no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. The laser Assisted Friction Stir Welding (LAFSW) combines a Friction Stir Welding machine and a laser system. Laser power is used to preheat and to plasticize the volume of the workpiece ahead of the rotating tool; the workpiece is then joined in the same way as in the conventional FSW process. In this work an Ytterbium fiber laser with maximum power of 4 kW and a commercial FSW machine were coupled. Both FSW and LAFSW tests were conducted on 3 mm thick 5754H111 aluminum alloy plates in lap joint configuration with a constant tool rotation rate and with different feed rates. The two processes were compared and evaluated in terms of differences in the microstructure and in the micro-hardness profile.

  7. Corrosion of aluminum alloy 2024 by microorganisms isolated from aircraft fuel tanks.

    PubMed

    McNamara, Christopher J; Perry, Thomas D; Leard, Ryan; Bearce, Ktisten; Dante, James; Mitchell, Ralph

    2005-01-01

    Microorganisms frequently contaminate jet fuel and cause corrosion of fuel tank metals. In the past, jet fuel contaminants included a diverse group of bacteria and fungi. The most common contaminant was the fungus Hormoconis resinae. However, the jet fuel community has been altered by changes in the composition of the fuel and is now dominated by bacterial contaminants. The purpose of this research was to determine the composition of the microbial community found in fuel tanks containing jet propellant-8 (JP-8) and to determine the potential of this community to cause corrosion of aluminum alloy 2024 (AA2024). Isolates cultured from fuel tanks containing JP-8 were closely related to the genus Bacillus and the fungi Aureobasidium and Penicillium. Biocidal activity of the fuel system icing inhibitor diethylene glycol monomethyl ether is the most likely cause of the prevalence of endospore forming bacteria. Electrochemical impedance spectroscopy and metallographic analysis of AA2024 exposed to the fuel tank environment indicated that the isolates caused corrosion of AA2024. Despite the limited taxonomic diversity of microorganisms recovered from jet fuel, the community has the potential to corrode fuel tanks. PMID:16522539

  8. Using capillary electrophoresis to study the chemical conditions within cracks in aluminum alloys.

    PubMed

    Cooper, K R; Kelly, R G

    1999-07-30

    The environment-assisted cracking (EAC) susceptibility of some aluminum alloys used for airplane structural components currently limits their use in the peak strength condition. Understanding the mechanism of EAC will facilitate the development of crack-resistant alloys with optimum mechanical properties. One component towards understanding the fundamental processes responsible for EAC is a comprehensive knowledge of the chemical conditions within cracks. The present work uses capillary electrophoresis (CE) to quantify the crack chemistry in order to provide insight into the nature of the mechanism controlling cracking. The highly restricted geometry of cracks in metals means that a crack typically contains less than 10 microliters of solution. The high mass sensitivity combined with the inherently robust nature of CE makes it an ideal analytical technique for this application. Complicating factors in the accurate determination of the crack environment include high levels of sodium present from the test solution. Low sample volume and analyte matrix complexity necessitated the development of specific sampling, extraction and analysis methods. Analysis of the crack solutions in EAC-susceptible material revealed high levels of Al3+, Mg2+, Zn2+, and Cl- near the crack tip. Cations arise from the anodic dissolution of the alloy, whereas chloride ingress from the external environment occurs to maintain solution electroneutrality within the crack. In contrast, EAC-resistant material exhibited significantly lower concentrations of dissolution products. PMID:10457501

  9. TIG welding of aluminum alloys for the APS storage ring - a UHV application

    SciTech Connect

    Goeppner, G.A.

    1996-05-29

    The Advanced Photon Source (APS) incorporates a 7-GeV positron storage ring 1104 meters in circumference. The storage ring vacuum system is designed to maintain a pressure of 1 nTorr or less with a circulating current of 300 mA to enable beam lifetimes of greater than 10 hours. The vacuum chamber is an aluminum extrusion of 6063T5 alloy. There are 235 separate aluminum vacuum chambers in the storage ring connected by stainless steel bellows assemblies. Aluminum was chosen for the vacuum chamber because it can be economically extruded and machined, has good thermal conductivity, low thermal emissivity, a low outgassing rate, low residual radioactivity, and is non-magnetic. The 6063 aluminum-silicon-magnesium alloy provides high strength combined with good machining and weldability characteristics. The extrusion process provides the interior surface finish needed for the ultrahigh vacuum (UHV) environments There are six different vacuum chambers with the same extrusion cross section. The average vacuum chamber length is 171.6 inches. The extruded vacuum chambers are welded to flange assemblies made up of machined 2219 aluminum alloy pieces and 2219 aluminum vacuum flanges from a commercial source.

  10. Laser direct marking applied to rasterizing miniature Data Matrix Code on aluminum alloy

    NASA Astrophysics Data System (ADS)

    Li, Xia-Shuang; He, Wei-Ping; Lei, Lei; Wang, Jian; Guo, Gai-Fang; Zhang, Teng-Yun; Yue, Ting

    2016-03-01

    Precise miniaturization of 2D Data Matrix (DM) Codes on Aluminum alloy formed by raster mode laser direct part marking is demonstrated. The characteristic edge over-burn effects, which render vector mode laser direct part marking inadequate for producing precise and readable miniature codes, are minimized with raster mode laser marking. To obtain the control mechanism for the contrast and print growth of miniature DM code by raster laser marking process, the temperature field model of long pulse laser interaction with material is established. From the experimental results, laser average power and Q frequency have an important effect on the contrast and print growth of miniature DM code, and the threshold of laser average power and Q frequency for an identifiable miniature DM code are respectively 3.6 W and 110 kHz, which matches the model well within normal operating conditions. In addition, the empirical model of correlation occurring between laser marking parameters and module size is also obtained, and the optimal processing parameter values for an identifiable miniature DM code of different but certain data size are given. It is also found that an increase of the repeat scanning number effectively improves the surface finish of bore, the appearance consistency of modules, which has benefit to reading. The reading quality of miniature DM code is greatly improved using ultrasonic cleaning in water by avoiding the interference of color speckles surrounding modules.

  11. Microstructural Evolution in the 2219 Aluminum Alloy During Severe Plastic Deformation

    SciTech Connect

    Kaibyshev, R.O.; Safarov, I.M.; Lesuen, D.R.

    2000-03-29

    Numerous investigations have demonstrated that intense plastic deformation is an attractive procedure for producing an ultrafine grain size in metallic materials. Torsional deformation under high pressure and equal-channel angular extrusion are two techniques that can produce microstructures with grain sizes in the submicrometer and nanometer range. Materials with these microstructures have many attractive properties. The microstructures formed by these two processing techniques are essentially the same and thus the processes occurring during deformation should be the same. Most previous studies have examined the final microstructures produced as a result of severe plastic deformation and the resulting properties. Only a limited number of studies have examined the evolution of microstructure. As a result, some important aspects of ultra-fine grain formation during severe plastic deformation remain unknown. There is also limited data on the influence of the initial state of the material on the microstructural evolution and mechanisms of ultra-fine grain formation. This limited knowledge base makes optimization of processing routes difficult and retards commercial application of these techniques. The objective of the present work is to examine the microstructure evolution during severe plastic deformation of a 2219 aluminum alloy. Specific attention is given to the mechanism of ultrafine grain formation as a result of severe plastic deformation.

  12. Mechanism of Ultrafine Grain Formation During Intense Plastic Straining in an Aluminum Alloy at Intermediate Temperatures

    SciTech Connect

    Kaibyshev, R.; Sitdikov, O.; Mazurina, I,; Lesuer, D. R.

    2000-09-21

    The mechanism of grain formation during equal channel angular extrusion (ECAE) in a 2219 Al alloy has been studied at intermediate and high temperatures. It was shown that continuous dynamic recrystallization (CDRX) occurred during intense plastic straining and resulted in the formation of submicrometer grains at temperatures ranging from 250 C to 300 C. Higher temperatures (< 300 C) hindered CDRX. This is caused by the fact that nucleation controls CDRX in the aluminum alloy. Dislocation rearrangements result in the formation of low angle boundary networks at moderate strain. The density of lattice dislocations determines the rate of subgrain formation. In addition, at lower temperatures a low energy dislocation structure (LEDS) forms concurrently with the subgrain structure and stabilizes it. The stability of the subgrain structure is very important for the resulting conversion of low angle boundaries into high angle ones with strain by extensive accumulation of mobile lattice dislocations. Increasing temperature in the range of intermediate temperatures suppresses LEDS formation and decreases the lattice dislocation density. This reduces the rate of the subgrain formation process and CDRX. As a result, at T = 400 C no recrystallized grains were found. At T = 475 C, the new grains form due to geometric dynamic recrystallization (GRX).

  13. Investigation on the Explosive Welding of 1100 Aluminum Alloy and AZ31 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Chen, Pengwan; Feng, Jianrui; Zhou, Qiang; An, Erfeng; Li, Jingbo; Yuan, Yuan; Ou, Sanli

    2016-07-01

    The undesirable properties of magnesium alloys include easy embrittlement, low oxidation resistance, and difficulty in welding with other materials. Their application in industry is, therefore, restricted. In this paper, plates of 1100 aluminum alloy and AZ31 magnesium alloy were successfully welded together using the explosive welding technique. The influences of the welding parameters on the weld quality were investigated. The surface morphology and microstructure near the weld interface were examined by optical microscopy, scanning electron microscopy (equipped with energy-dispersive x-ray spectroscopy), and transmission electron microscopy. The experimental results demonstrated the typical wavy bonding interface. In addition, elemental diffusion with a thickness of approximately 3 μm occurred near the bonding interface. The two plates were joined together well at the atomic scale. Nanograins with a size of approximately 5 nm were observed in the diffusion layer. The microhardness and shear strength were measured to evaluate the mechanical properties, which confirmed that a high quality of bonding was acquired.

  14. A Numerical Simulation for Dissimilar Aluminum Alloys Joined by Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Hamilton, Carter; Kopyściański, Mateusz; Węglowska, Aleksandra; Dymek, Stanisław; Pietras, Adam

    2016-06-01

    Dissimilar aluminum alloy sheets of 2017A-T451 and 7075-T651 (6 mm thickness) were friction stir welded in a butt weld configuration. A numerical simulation of the joining process was developed to visualize the material flow patterns and temperature distribution and to correlate the microstructure to the hardness behavior. Due to the complementary downward flow of surface material into the workpiece thickness and upward flow of mid-plane and bottom-plane material, the weld nugget is composed of alternating layers of 7075 and 2017A. These layers have unique temperature histories depending on the material's initial location within the cross section; therefore, they also have distinctive precipitate distributions. Supersaturated surface material flows into the process zone and forms a core in which GP zones reprecipitate upon cooling. Mid-plane and bottom-plane material flow toward the workpiece surface and encompass the surface material core. Within this region, the weld temperatures overage the equilibrium θ phase in 2017A, decreasing the hardness, and at the same time, dissolve the equilibrium η/T phase in the 7075, leading to reprecipitation of GP zones upon cooling and a hardness recovery.

  15. Control of back surface reflectance from aluminum alloyed contacts on silicon solar cells

    SciTech Connect

    Cudzinovic, M.; Sopori, B.

    1996-05-01

    A process for forming highly reflective aluminum back contacts with low contact resistance to silicon solar cells is described. By controlling the process conditions, it is possible to vary the silicon/aluminum interface from a specular to a diffuse reflector while maintaining a high interface reflectance. The specular interface is found to be a uniform silicon/aluminum alloy layer a few angstroms thick that has epitaxially regrown on the silicon. The diffuse interface consists of randomly distributed (111) pyramids produced by crystallographic out-diffusion of the bulk silicon. The light trapping ability of the diffuse contact is found to be close to the theoretical limit. Both types of contacts are found to have specific contact resistivities of 10{sup {minus}5} {Omega}-cm{sup 2}. The process for forming the contacts involves illuminating the devices with tungsten halogen lamps. The process is rapid (under 100 s) and low temperature (peak temperature < 580{degrees}C), making it favorable for commercial solar cell fabrication.

  16. Short-crack growth behaviour in an aluminum alloy: An AGARD cooperative test program

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.; Edwards, P. R.

    1988-01-01

    An AGARD Cooperative Test Program on the growth of short fatigue cracks was conducted to define the significance of the short-crack effect, to compare test results from various laboratories, and to evaluate an existing analytical crack-growth prediction model. The initiation and growth of short fatigue cracks (5 micrometer to 2 mm) from the surface of a semi-circular notch in 2024-T3 aluminum alloy sheet material were monitored under various load histories. The cracks initiated from inclusion particle clusters or voids on the notch surface and generally grew as surface cracks. Tests were conducted under several constant-amplitude (stress ratios of -2, -1, 0, and 0.5) and spectrum (FALSTAFF and Gaussian) loading conditions at 3 stress levels each. Short crack growth was recorded using a plastic-replica technique. Over 250 edge-notched specimens were fatigue tested and nearly 950 cracks monitored by 12 participants from 9 countries. Long crack-growth rate data for cracks greater than 2 mm in length were obtained over a wide range in rates (10 to the -8 to 10 to the -1 mm/cycle) for all constant-amplitude loading conditions. Long crack-growth rate data for the FALSTAFF and Gaussian load sequences were also obtained.

  17. Surface characterization of carbon fiber polymer composites and aluminum alloys after laser interference structuring

    DOE PAGESBeta

    Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian; Warren, Charles David; Daniel, Claus

    2016-05-03

    Here, the increasing use of Carbon Fiber-reinforced Polymer matrix Composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (a) structuring of the AL 5182 surface, (b) removal of the resin layer on top of carbon fibers, and (c) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg - T83 epoxy, 5 ply thick, 0/90o plaques weremore » used. The effect of laser fluence, scanning speed, and number of shots-per-spot was investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope (SEM) imaging were used to study the effect of the laser processing on surface morphology.« less

  18. Effects of porosity on weld-joint tensile strength of aluminum alloys

    NASA Technical Reports Server (NTRS)

    Lovoy, C. V.

    1974-01-01

    Tensile properties in defect-free weldments of aluminum alloys 2014-T6 and 2219-T87 (sheet and plate) are shown to be related to the level or concentration of induced simulated porosity. The scatter diagram shows that the ultimate tensile strength of the weldments displays the most pronounced linear relationship with the level of porosity. The relationships between yield strength or elongation and porosity are either trivial or inconsequential in the lower and intermediate levels of porosity content. In highly concentrated levels of porosity, both yield strength and elongation values decrease markedly. Correlation coefficients were obtained by simple straight line regression analysis between the variables of ultimate tensile strength and pore level. The coefficients were greater, indicating a better correlation, using a pore area accumulation concept or pore volume accumulation than the accumulation of the pore diameters. These relationships provide a useful tool for assessing the existing aerospace radiographic acceptance standards with respect to permissible porosity. In addition, these relationships, in combination with known design load requirements, will serve as an engineering guideline in determining when a weld repair is necessary based on accumulative pore level as detected by radiographic techniques.

  19. Neutral gas desorption and photoelectric emission from aluminum alloy vacuum chambers exposed to synchrotron radiation

    SciTech Connect

    Groebner, O.; Mathewson, A.G.; Strubin, P.; Alge, E.; Souchet, R.

    1989-03-01

    In an aluminum alloy vacuum chamber exposed to synchrotron radiation, the photoelectron currents produced were measured with the photons incident at low angles on the side wall and compared with normal incidence. The calculated photocurrents for normal incidence, using published values of the photoyield for oxidized Al, agree to within 15% with the measured values. Differences in the photocurrent dependence on photon spectrum at normal and glancing incidence were attributed to low-energy photons being totally reflected and hence producing no photoelectrons. It was established that, at glancing angles of incidence down to 11 mrad, a substantial: more than 20%: fraction of the synchrotron radiation is scattered around the vacuum chamber from the initial point of impact. During exposure to synchrotron radiation, the gases desorbed were H/sub 2/, CO, CO/sub 2/, and CH/sub 4/. The similar shapes of the dependence of the gas desorption and the photoelectron currents on the photon spectrum suggested that it is mainly the photoelectrons that are contributing to the desorption. It was estimated that electrons of 60 eV would produce the same gas desorption as synchrotron radiation with a critical energy of 3 keV.

  20. Effect of nanostructuring on the elastic properties of aluminum alloy AMg6

    SciTech Connect

    Prokhorov, V. Perfilov, S.; Korobov, A. Kokshaiskii, A.; Volkov, A.

    2015-10-28

    We experimentally investigated the nanostructuring effect on the elastic properties of aluminum alloy AMg6 (Al–Mg–Mn system). The n-AMg6 nanostuctured specimens were prepared from a commercial polycrystalline alloy by refining and homogenizing a mixture of small chips of the alloy in a planetary mill. The resulting product consists of 200-500-micron agglomerates of nanoparticles with average nanoparticle size ∼ 40–60 nanometer according to the X-ray analysis. The compacted nanopowder was extruded at a temperature of 300°C with a reduction of cross-sectional area at least 4 times to 90 mm diameter. High resolution transmission electron microscopy studies confirmed the presence of the nanostructure with a grain size of ∼60 nanometers. For the experiments, nine parallelepiped shape specimens of 20×20×40 mm{sup 3} size were cut from the central and peripheral parts of the n-AMg6 rod. We measured of the second-order and third-order elastic coefficients of the obtained samples by ultrasonic method. The same measurements were made on specimens of the primary AMg6 alloy for comparison.

  1. Some observations on cyclic deformation structures in the high-strength commercial aluminum alloy AA 7150

    SciTech Connect

    Hanlon, D.N.; Rainforth, W.M.

    1998-11-01

    Load-controlled fatigue testing of the aluminum alloy AA 7150 has been conducted using four-point bending with an R ratio of + 0.1 over a range of maximum stress levels from 60 to 120% of the 0.2% proof stress. The alloy, in the form of 12.5-mm rolled plate, was investigated in underaged (UA), peak-aged (PA), and overaged (OA) conditions, corresponding to a change in average precipitate sizes from 5 nm in the UA condition to 21 nm in the OA condition. Three orientations of the plate were investigated. Orientation and aging condition influenced the degree of surface topographical development but not fatigue life. Detailed transmission electron microscopy (TEM) of the fatigued surface indicated that deformation in all aging conditions occurred by planar slip. Slip was generally restricted to a single slip system within each grain, and subgrain boundaries offered little resistance to dislocation movement facilitating long slip line lengths (measured up to 310 {micro}m) between adjacent high-angle grain boundaries. Planar slip observed in the OA condition is attributed to shearing of large strengthening precipitates, which is promoted by long slip line lengths. No evidence of surface specific changes in slip character was observed.

  2. Time dependence of solid-particle impingement erosion of an aluminum alloy

    NASA Technical Reports Server (NTRS)

    Veerabhadrarao, P.; Buckley, D. H.

    1983-01-01

    Erosion studies were conducted on 6061-T6511 aluminum alloy by using jet impingement of glass beads and crushed glass particles to investigate the influence of exposure time on volume loss rate at different pressures. The results indicate a direct relationship between erosion-versus-time curves and pitmorphology (width, depth, and width-depth ratio)-versus-time curves for both glass forms. Extensive erosion data from the literature were analyzed to find the variations of erosion-rate-versus-time curves with respect to the type of device, the size and shape of erodent particles, the abrasive charge, the impact velocity, etc. Analysis of the experimental data, obtained with two forms of glass, resulted in three types of erosion-rate-versus-time curves: (1) curves with incubation, acceleration, and steadystate periods (type 1); (2) curves with incubation, acceleration, decleration, and steady-state periods (type 3); and (3) curves with incubation, acceleration, peak rate, and deceleration periods (type 4). The type 4 curve is a less frequently seen curve and was not reported in the literature. Analysis of extensive literature data generally indicated three types of erosion-rate-versus-time curves. Two types (types 1 and 3) were observed in the present study; the third type involves incubation (and deposition), acceleration, and steady-state periods (type 2). Examination of the extensive literature data indicated that it is absolutely necessary to consider the corresponding stages or periods of erosion in correlating and characterizing erosion resistance of a wide spectrum of ductile materials.

  3. M551 metals melting experiment. [space manufacturing of aluminum alloys, tantalum alloys, stainless steels

    NASA Technical Reports Server (NTRS)

    Li, C. H.; Busch, G.; Creter, C.

    1976-01-01

    The Metals Melting Skylab Experiment consisted of selectively melting, in sequence, three rotating discs made of aluminum alloy, stainless steel, and tantalum alloy. For comparison, three other discs of the same three materials were similarly melted or welded on the ground. The power source of the melting was an electron beam unit. Results are presented which support the concept that the major difference between ground base and Skylab samples (i.e., large elongated grains in ground base samples versus nearly equiaxed and equal sized grains in Skylab samples) can be explained on the basis of constitutional supercooling, and not on the basis of surface phenomena. Microstructural observations on the weld samples and present explanations for some of these observations are examined. In particular, ripples and their implications to weld solidification were studied. Evidence of pronounced copper segregation in the Skylab A1 weld samples, and the tantalum samples studied, indicates a weld microhardness (and hence strength) that is uniformly higher than the ground base results, which is in agreement with previous predictions. Photographs are shown of the microstructure of the various alloys.

  4. Ultrasonic butt welding of aluminum, aluminum alloy and stainless steel plate specimens.

    PubMed

    Tsujino, Jiromaru; Hidai, Kazuaki; Hasegawa, Atsushi; Kanai, Ryoichi; Matsuura, Hisanori; Matsushima, Kaoru; Ueoka, Tetsugi

    2002-05-01

    Welding characteristics of aluminum, aluminum alloy and stainless steel plate specimens of 6.0 mm thickness by a 15 kHz ultrasonic butt welding system were studied. There are no detailed welding condition data of these specimens although the joining of these materials are required due to anticorrosive and high strength characteristics for not only large specimens but small electronic parts especially. These specimens of 6.0 mm thickness were welded end to end using a 15 kHz ultrasonic butt welding equipment with a vibration source using eight bolt-clamped Langevin type PZT transducers and a 50 kW static induction thyristor power amplifier. The stainless steel plate specimens electrolytically polished were joined with welding strength almost equal to the material strength under rather large vibration amplitude of 25 microm (peak-to-zero value), static pressure 70 MPa and welding time of 1.0-3.0 s. The hardness of stainless steel specimen adjacent to a welding surface increased about 20% by ultrasonic vibration. PMID:12159968

  5. Computational Analysis of Material Flow During Friction Stir Welding of AA5059 Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Arakere, G.; Pandurangan, B.; Ochterbeck, J. M.; Yen, C.-F.; Cheeseman, B. A.; Reynolds, A. P.; Sutton, M. A.

    2012-09-01

    Workpiece material flow and stirring/mixing during the friction stir welding (FSW) process are investigated computationally. Within the numerical model of the FSW process, the FSW tool is treated as a Lagrangian component while the workpiece material is treated as an Eulerian component. The employed coupled Eulerian/Lagrangian computational analysis of the welding process was of a two-way thermo-mechanical character (i.e., frictional-sliding/plastic-work dissipation is taken to act as a heat source in the thermal-energy balance equation) while temperature is allowed to affect mechanical aspects of the model through temperature-dependent material properties. The workpiece material (AA5059, solid-solution strengthened and strain-hardened aluminum alloy) is represented using a modified version of the classical Johnson-Cook model (within which the strain-hardening term is augmented to take into account for the effect of dynamic recrystallization) while the FSW tool material (AISI H13 tool steel) is modeled as an isotropic linear-elastic material. Within the analysis, the effects of some of the FSW key process parameters are investigated (e.g., weld pitch, tool tilt-angle, and the tool pin-size). The results pertaining to the material flow during FSW are compared with their experimental counterparts. It is found that, for the most part, experimentally observed material-flow characteristics are reproduced within the current FSW-process model.

  6. Calorimetric Studies of Precipitation and Dissolution Kinetics in Aluminum Alloys 2219 and 7075

    NASA Astrophysics Data System (ADS)

    Papazian, John M.

    1982-05-01

    Differential scanning calorimetry (DSC) was used to study the kinetics of precipitation and dissolution of metastable and stable phases in aluminum alloys 2219 and 7075. A comparison of DSC scans obtained at heating rates of 1, 5, 10, and 20 K per minute showed that, during a DSC scan, the rates of precipitation of θ' and θ in 2219 and η' and η in 7075 were limited by their reaction kinetics. Likewise, the rates of dissolution of GP zones, θ' and η', were found to be dominated by kinetics. In contrast, the dissolution of θ and η was dominated by the thermodynamic equilibrium between these phases and the matrix. Analysis of the kinetically dominated reaction peaks and their dependence on heating rate and particle size showed that the GP zone dissolution reaction could best be described by a three-dimensional volume diffusion limited rate expression with an activation energy equal to that for diffusion. The rate of formation of θ' was best described by an Avrami expression with n = 1.1, indicating that nucleation was not the rate controlling step. A pronounced dependence of the θ' formation rate on prior plastic deformation was observed and ascribed to the influence of the matrix dislocation density on diffusivity.

  7. Comments on the origin of acoustic emission in fatigue testing of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Heiple, C. R.; Carpenter, S. H.; Armentrout, D. L.

    The size of acoustic emission (AE) signals expected from inclusion fracture during fatigue testing of 7075 aluminum has been estimated on the basis of previous measurements of AE produced by the fracture of boron particles incorporated into 2219 aluminum. The AF signal size expected from deformation in the plastic zone ahead of the fatigue crack was estimated from the results of tensile tests on 7075 aluminum. The signals predicted from both processes are near or below the noise level in the fatigue experiments and are therefore far too small to account for the signals actually observed. Nearly simultaneous fracture of multiple inclusions could produce signals as large as those observed in fatigue tests of 7075 aluminum, however, fatigue tests of 7050 aluminum produced signals as large or larger than in 7075. Since 7050 has substantially fewer inclusions than 7075, the simultaneous failure of multiple inclusions is unlikely to be a major AE source in fatigue testing of either aluminum alloy. Thus, the most probable source of acoustic emission during fatigue testing of 7075 and 7050 aluminum is the crack advance itself. The measured crack advance per cycle is large enough to release sufficient elastic energy to account for the AE signals observed.

  8. Surface characterization of aluminum alloy 2017 as a vacuum vessel for nuclear fusion devices

    NASA Astrophysics Data System (ADS)

    Mohri, M.; Odagiri, H.; Satake, T.; Yamashina, T.; Oikawa, H.; Kanedo

    1984-05-01

    The surface characterization of a type 2017 aluminum alloy was performed to examine their potentials for the use of nuclear fusion devices mainly from a view point of vacuum engineering. Three different samples treated with milling (Sample A), discharging (Sample B) and chemical etching (Sample C) were examined in terms of their surface morphology by surface profilometry, scanning electron microscopy, and xenon adsorption. The surface roughness factor was obtained as 5.9, 42.8 and 9.0 for sample A, Sample B and Sample C, respectively. The thicknesses of surface oxide layers were measured by the sputter-AES method as 40 Å, 80 Å and 70 Å for Sample A, Sample B and Sample C, respectively. Outgassing characteristics of these surfaces were measured by a thermal desorption method. H 2O, CO and CO 2 were main outgassing components and the maximum desorption temperature was observed in the range between 110 °C and 160 °C. The surface roughness factor and the thickness of the surface oxide layer were found to be important factors for outgassing characteristics.

  9. Surface Characterization of Carbon Fiber Polymer Composites and Aluminum Alloys After Laser Interference Structuring

    NASA Astrophysics Data System (ADS)

    Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian; Warren, Charles D.; Daniel, Claus

    2016-07-01

    The increasing use of carbon fiber-reinforced polymer matrix composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (1) structuring of the AL 5182 surface, (2) removal of the resin layer on top of carbon fibers, and (3) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg—T83 epoxy, 5 ply thick, 0°/90° plaques were used. The effects of laser fluence, scanning speed, and number of shots-per-spot were investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope imaging were used to study the effect of the laser processing on the surface morphology. It was found that an effective resin ablation and a low density of broken fibers for CFPC specimens was attained using laser fluences of 1-2 J/cm2 and number of 2-4 pulses per spot. A relatively large area of periodic line structures due to energy interference were formed on the aluminum surface at laser fluences of 12 J/cm2 and number of 4-6 pulses per spot.

  10. Investigation on the Explosive Welding of 1100 Aluminum Alloy and AZ31 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Chen, Pengwan; Feng, Jianrui; Zhou, Qiang; An, Erfeng; Li, Jingbo; Yuan, Yuan; Ou, Sanli

    2016-06-01

    The undesirable properties of magnesium alloys include easy embrittlement, low oxidation resistance, and difficulty in welding with other materials. Their application in industry is, therefore, restricted. In this paper, plates of 1100 aluminum alloy and AZ31 magnesium alloy were successfully welded together using the explosive welding technique. The influences of the welding parameters on the weld quality were investigated. The surface morphology and microstructure near the weld interface were examined by optical microscopy, scanning electron microscopy (equipped with energy-dispersive x-ray spectroscopy), and transmission electron microscopy. The experimental results demonstrated the typical wavy bonding interface. In addition, elemental diffusion with a thickness of approximately 3 μm occurred near the bonding interface. The two plates were joined together well at the atomic scale. Nanograins with a size of approximately 5 nm were observed in the diffusion layer. The microhardness and shear strength were measured to evaluate the mechanical properties, which confirmed that a high quality of bonding was acquired.

  11. A New Approach to Ultrasonic Degassing to Improve the Mechanical Properties of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Puga, H.; Barbosa, J.; Teixeira, J. C.; Prokic, M.

    2014-10-01

    Ultrasonic degassing of liquid metals has been studied over the last years, but it has been limited to laboratorial scale experiments of low volumes of melt. In this work, the combined effect of acoustic cavitation with metal agitation induced by the mechanical vibration of the ultrasonic radiator itself was studied, using a specially designed low frequency mechanical vibrator coupled to the ultrasonic degassing unit. Liquid motion in water was characterized by high speed digital Photron—FastCam APX RS video camera and Laser Doppler Anemometry to select the most favorable US and mechanical vibrator frequencies to induce suitable water stirring. Selected parameters were used to degas 10 L of AlSi9Cu3(Fe) alloy. A suitable piezoelectric sensor was used to measure sound pressure at different distances from the sonotrode to identify the zone of higher acoustic activity. Results have shown that melt stirring significantly improves US degassing efficiency (since it is possible to achieve almost the aluminum alloy theoretical density after 3 min processing time) which contributed to increase the tensile properties of the alloy.

  12. The Role of Precipitates in the Behavior of Young's Modulus in Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Villuendas, Aranzazu; Jorba, Jordi; Roca, Antoni

    2014-08-01

    The behavior of Young's modulus, E, was determined in aluminum alloys such as AA7075 and AA2024 at room temperature under various thermomechanical treatments. E was almost 2 pct (AA7075) and 3 pct (AA2024) lower for these materials after solution heat treatment and quenching than after annealing. When the aging time was increased, values of E tended to approach the annealing values. The variation observed was attributed to structural changes during the thermal treatments. However, when the alloys were cold deformed before or after aging, no appreciable changes in E were observed. This behavior is quite different to that observed in cold-worked pure aluminum (and also in pure iron), in which E decreased to a minimum (7 to 10 pct reduction in values) and then partially recovered with additional cold working. The variation in behavior with cold working observed in a pure material and other materials that contain a second phase with nanometric precipitates was correlated with the density of dislocations and the length of the dislocation segments generated during the cold working process.

  13. Characterization of ironing in the hole-flanging process of an aluminum alloy

    NASA Astrophysics Data System (ADS)

    Kacem, A.; Krichen, A.; Manach, P. Y.

    2011-08-01

    Hole-flanging is a sheet metal forming process which is often used to produce a flange around holes. Many industrial applications require a longer flange that can be used for example to increase bearing surface or to increase the number of threads that will fit in a tapped hole. Ironing is usually used during such process to increase the flange height. Due to the thinning of the flange caused by edge stretching, some difficulties arise when trying to set a clearance value for which the process is performed with ironing. Therefore, the occurrence of ironing needs to be more clarified. It is also important to quantify the effect of ironing intensity in the flange geometry. In the present work, FE simulations and experiments are performed to investigate hole-flanging with and without ironing. For this purpose, hole-flanging is carried out by varying the clearance between the punch and the die while keeping constant the other parameters. The aim is to identify the occurrence of ironing by the determination of a limit between the hole-flanging with ironing and the hole-flanging without ironing. Attention is focused on studying the effect of the hole-flanging conditions on the punch load, the forming kinematics and the final shape. The experiments are carried out to check the FE results on an aluminum alloy.

  14. Slow strain rate testing of aluminum alloy 7050 in different tempers using various synthetic environments

    SciTech Connect

    Braun, R.

    1997-06-01

    The slow strain rate testing (SSRT) technique was used to investigate the stress corrosion cracking (SCC) behavior of aluminum alloy Al 7050 in different tempers in various electrolytes at the free-corrosion potential. Smooth tensile specimens were strained dynamically in the short transverse direction under permanent immersion conditions. Strain rates were from 5 {times} 10{sup {minus}8}/s to 1 {times} 10{sup {minus}4}/s. Using substitute ocean water, Al 7050 was found sensitive and immune to environmentally assisted cracking in the peak-aged temper T651 and in the over-aged temper T7351, respectively. In the less-over-aged heat treatment T7651, fracture energy data revealed a large scatter. An aqueous solution of 0.5 M sodium perchlorate was not conducive to environmentally assisted cracking. SSRT performed in an aqueous solution of 0.1 M sodium chloride + 0.05 M sodium sulfate + 0.05 M sodium nitrate + 0.01 M sodium bicarbonate at pH 3.5 indicated SCC susceptibility for Al 7050-T651. The latter electrolyte did not promote SCC with the alloy in the heat treatments T7651 and T7351. Scatter was observed in the fracture energy data of Al 7050-T7351 specimens dynamically strained in the mixed salt solution. Deterioration was attributed to pitting attack, as supported by fractography.

  15. Stress ratio effects in fatigue of lost foam cast aluminum alloy 356

    NASA Astrophysics Data System (ADS)

    Palmer, David E.

    Lost foam casting is a highly versatile metalcasting process that offers significant benefits in terms of design flexibility, energy consumption, and environmental impact. In the present work, the fatigue behavior of lost foam cast aluminum alloy 356, in conditions T6 and T7, was investigated, under both zero and non-zero mean stress conditions, with either as-cast or machined surface finish. Scanning electron microscopy was used to identify and measure the defect from which fatigue fracture initiated. Based on the results, the applicability of nine different fatigue mean stress equations was compared. The widely-used Goodman equation was found to be highly non-conservative, while the Stulen, Topper-Sandor, and Walker equations performed reasonably well. Each of these three equations includes a material-dependent term for stress ratio sensitivity. The stress ratio sensitivity was found to be affected by heat treatment, with the T6 condition having greater sensitivity than the T7 condition. The surface condition (as-cast vs. machined) did not significantly affect the stress ratio sensitivity. The fatigue life of as-cast specimens was found to be approximately 60--70% lower than that of machined specimens at the same equivalent stress. This reduction could not be attributed to pore size alone, and is suspected to be due to the greater concentration of pyrolysis products at the as-cast surface. Directions for future work, including improved testing methods and some possible methods of improving the properties of lost foam castings, are discussed.

  16. Damage Tolerance Assessment of Friction Pull Plug Welds in an Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    McGill, Preston; Burkholder, Jonathan

    2012-01-01

    Friction stir welding is a solid state welding process used in the fabrication of cryogenic propellant tanks. Self-reacting friction stir welding is one variation of the friction stir weld process being developed for manufacturing tanks. Friction pull plug welding is used to seal the exit hole that remains in a circumferential self-reacting friction stir weld. A friction plug weld placed in a self-reacting friction stir weld results in a non-homogenous weld joint where the initial weld, plug weld, their respective heat affected zones and the base metal all interact. The welded joint is a composite plastically deformed material system with a complex residual stress field. In order to address damage tolerance concerns associated with friction plug welds in safety critical structures, such as propellant tanks, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size. Test data relating residual strength capability to flaw size in an aluminum alloy friction plug weld will be presented.

  17. Wear and Friction Characteristics of AlN/Diamond-Like Carbon Hybrid Coatings on Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Nakamura, Masashi; Kubota, Sadayuki; Suzuki, Hideto; Haraguchi, Tadao

    2015-10-01

    The use of diamond-like carbon (DLC) coatings has the potential to greatly improve the wear resistance and friction of aluminum alloys, but practical application has so far been limited by poor adhesion due to large difference in hardness and elasticity between the two materials. This study investigates the deposition of DLC onto an Al-alloy using an intermediate AlN layer with a graded hardness to create a hybrid coating. By controlling the hardness of the AlN film, it was found that the wear life of the DLC film could be improved 80-fold compared to a DLC film deposited directly onto Al-alloy. Furthermore, it was demonstrated through finite element simulation that creating a hardness gradient in the AlN intermediate layer reduces the distribution of stress in the DLC film, while also increasing the force of adhesion between the DLC and AlN layers. Given that both the DLC and AlN films were deposited using the same unbalanced magnetron sputtering method, this process is considered to represent a simple and effective means of improving the wear resistance of Al-alloy components commonly used within the aerospace and automotive industries.

  18. Separating Effect of a Novel Combined Magnetic Field on Inclusions in Molten Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    He, Yanjie; Li, Qiulin; Liu, Wei

    2012-10-01

    The feasibility and effectiveness of a novel combined magnetic field (CMF) on the removal of inclusions with a density smaller than the surrounding melt were investigated. The experiment of the separating effect of CMF was conducted on a laboratory-scale apparatus by the simultaneous application of a rotating magnetic field (RMF) and a downward traveling magnetic field (TMF). Primary silicon particles precipitating from the solidification process of Al-Si-Cu alloy were regarded as the inclusions in a molten aluminum alloy. It was found that a CMF consisting of both a RMF and a downward TMF was able to separate silicon particles from the molten Al-Si-Cu alloy by making these particles migrate vertically toward the upper part of the samples. Compared with downward TMF or RMF, CMF improved the separating effectiveness substantially. It was proposed that this type of CMF was approved to be highly effective at eliminating the inclusions with a density smaller than the surrounding molten alloy. A tentative mechanism for the high separating effect of CMF was discussed.

  19. Metallurgical Mechanisms Controlling Mechanical Properties of Aluminum Alloy 2219 Produced by Electron Beam Freeform Fabrication

    NASA Technical Reports Server (NTRS)

    Domack, Marcia S.; Tainger, Karen M.

    2006-01-01

    The electron beam freeform fabrication (EBF3) layer-additive manufacturing process has been developed to directly fabricate complex geometry components. EBF3 introduces metal wire into a molten pool created on the surface of a substrate by a focused electron beam. Part geometry is achieved by translating the substrate with respect to the beam to build the part one layer at a time. Tensile properties demonstrated for electron beam deposited aluminum and titanium alloys are comparable to wrought products, although the microstructures of the deposits exhibit cast features. Understanding the metallurgical mechanisms controlling mechanical properties is essential to maximizing application of the EBF3 process. Tensile mechanical properties and microstructures were examined for aluminum alloy 2219 fabricated over a range of EBF3 process variables. Unique microstructures were observed within the deposited layers and at interlayer boundaries, which varied within the deposit height due to microstructural evolution associated with the complex thermal history experienced during subsequent layer deposition. Microstructures exhibited irregularly shaped grains with interior dendritic structures, described based on overall grain size, morphology, distribution, and dendrite spacing, and were correlated with deposition parameters. Fracture features were compared with microstructural elements to define fracture paths and aid in definition of basic processing-microstructure-property correlations.

  20. Computer-assisted Rheo-forging Processing of A356 Aluminum Alloys

    SciTech Connect

    Kim, H. H.; Kang, C. G.

    2010-06-15

    Die casting process has been used widely for complex automotive products such as the knuckle, arm and etc. Generally, a part fabricated by casting has limited strength due to manufacturing defects by origin such as the dendrite structure and segregation. As an attempt to offer a solution to these problems, forging has been used as an alternative process. However, the forging process provides limited formability for complex shape products. Rheo-forging of metal offers not only superior mechanical strength but also requires significantly lower machine loads than solid forming processes. In order to produce semi-solid materials of the desired microstructure, a stirring process is applied during solidification of A356 aluminum molten state. This paper presents the results of an A356 aluminum alloy sample, which were obtained by experiment and by simulation using DEFORM 3D V6.1. Samples of metal parts were subsequently fabricated by using hydraulic press machinery. In order to compare the influence of loading method, two types of samples were fabricated: (1) samples fabricated under direct loading die sets (2) those fabricated under indirect loading die sets. The formability and defects, which were predicted by FEM simulation, were similar to those of samples used in practice.

  1. Metallurgical Mechanisms Controlling Mechanical Properties of Aluminum Alloy 2219 Produced By Electron Beam Freeform Fabrication

    NASA Technical Reports Server (NTRS)

    Domack, Marcia S.; Taminger, Karen M. B.; Begley, Matthew

    2006-01-01

    The electron beam freeform fabrication (EBF3) layer-additive manufacturing process has been developed to directly fabricate complex geometry components. EBF3 introduces metal wire into a molten pool created on the surface of a substrate by a focused electron beam. Part geometry is achieved by translating the substrate with respect to the beam to build the part one layer at a time. Tensile properties have been demonstrated for electron beam deposited aluminum and titanium alloys that are comparable to wrought products, although the microstructures of the deposits exhibit features more typical of cast material. Understanding the metallurgical mechanisms controlling mechanical properties is essential to maximizing application of the EBF3 process. In the current study, mechanical properties and resulting microstructures were examined for aluminum alloy 2219 fabricated over a range of EBF3 process variables. Material performance was evaluated based on tensile properties and results were compared with properties of Al 2219 wrought products. Unique microstructures were observed within the deposited layers and at interlayer boundaries, which varied within the deposit height due to microstructural evolution associated with the complex thermal history experienced during subsequent layer deposition. Microstructures exhibited irregularly shaped grains, typically with interior dendritic structures, which were described based on overall grain size, morphology, distribution, and dendrite spacing, and were correlated with deposition parameters. Fracture features were compared with microstructural elements to define fracture paths and aid in definition of basic processing-microstructure-property correlations.

  2. Creep crack growth behavior of aluminum alloy 2519. Part 2: Numerical analysis

    SciTech Connect

    Hall, D.E.; Hamilton, B.C.; McDowell, D.L.; Saxena, A.

    1997-12-31

    The experimental analysis of high temperature fracture in Aluminum Alloy 2519-T87 presented in Part 1 of this paper highlighted the creep-brittle fracture characteristics of the material and showed reasonable correlation of crack growth rates with the stress intensity factor K. Part 2 continues this investigation numerically using growing crack finite element analyses. Experimentally observed crack growth histories of four aluminum 2519-T87 compact specimens are enforced by controlling the rate of release of finite element nodes along the crack growth path to gain insight into the relation of the crack tip fields to far field fracture parameters and to crack growth rates. A variable time-step, nodal-release algorithm is presented to model the high strain rates that occur during the initial stages of crack growth. The numerical results indicate an initial transient period of crack growth followed by a quasi-steady-state crack growth regime in which the crack tip fields change slowly with increasing crack length. Transition of crack growth to the quasi-steady-state regime, where similitude and small-scale creep conditions roughly exist, is given by a transition time t{sub g} that depends on the crack growth history and material properties. Excellent correlation of the stress intensity factor K with the crack growth rates is observed after time t{sub g}. Experimental difficulties in measuring the creep component of the load-line deflection rate are also discussed.

  3. Instability of the Liquid Metal-Pattern Interface in the Lost Foam Casting of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Griffiths, W. D.; Ainsworth, M. J.

    2016-06-01

    The nature of the liquid metal-pattern interface during mold filling in the Lost Foam casting of aluminum alloys was investigated using real-time X-ray radiography for both normal expanded polystyrene, and brominated polystyrene foam patterns. Filling the pattern under the action of gravity from above or below had little effect on properties, both cases resulting in a large scatter of tensile strength values, (quantified by their Weibull Modulus). Countergravity filling at different velocities demonstrated that the least scatter of tensile strength values (highest Weibull Modulus) was associated with the slowest filling, when a planar liquid metal-pattern interface occurred. Real-time X-ray radiography showed that the advancing liquid metal front became unstable above a certain critical velocity, leading to the entrainment of the degrading pattern material and associated defects. It has been suggested that the transition of the advancing liquid metal-pattern interface into an unstable regime may be a result of Saffman-Taylor Instability.

  4. Application of slip-band visualization technique to tensile analysis of laser-welded aluminum alloy

    NASA Astrophysics Data System (ADS)

    Muchiar, -; Yoshida, Sanichiro J.; Widiastuti, Rini; Kusnowo, A.; Takahashi, Kunimitsu; Sato, Shunichi

    1997-03-01

    Recently we have developed a new optical interferometric technique capable of visualizing slip band occurring in a deforming solid-state object. In this work we applied this technique to a tensile analysis of laser-welded aluminum plate samples, and successfully revealed stress concentration that shows strong relationships with the tensile strength and the fracture mechanism. We believe that this method is a new, convenient way to analyze the deformation characteristics of welded objects and evaluate the quality of welding. The analysis has been made for several types of aluminum alloys under various welding conditions, and has shown the following general results. When the penetration is deep, a slip band starts appearing at the fusion zone in an early stage of the elastic region of the strain-stress curve and stays there till the sample fractures at that point. When the penetration is shallow, a slip band appears only after the yield point and moves vigorously over the whole surface of the sample till a late stage of plastic deformation when the slip band stays at the fusion zone where the sample eventually fractures. When the penetration depth is medium, some intermediate situation of the above two extreme cases is observed.

  5. Mechanisms of fatigue crack retardation following single tensile overloads in powder metallurgy aluminum alloys

    NASA Technical Reports Server (NTRS)

    Bray, G. H.; Reynolds, A. P.; Starke, E. A., Jr.

    1992-01-01

    In ingot metallurgy (IM) alloys, the number of delay cycles following a single tensile overload typically increases from a minimum at an intermediate baseline stress intensity range, Delta-K(B), with decreasing Delta-K(B) approaching threshold and increasing Delta-K(B) approaching unstable fracture to produce a characteristic 'U' shaped curve. Two models have been proposed to explain this behavior. One model is based on the interaction between roughness and plasticity-induced closure, while the other model only utilizes plasticity-induced closure. This article examines these models, using experimental results from constant amplitude and single overload fatigue tests performed on two powder metallurgy (PM) aluminum alloys, AL-905XL and AA 8009. The results indicate that the 'U'-shaped curve is primarily due to plasticity-induced closure, and that the plasticity-induced retardation effect is through-thickness in nature, occurring in both the surface and interior regions. However, the retardation effect is greater at the surface, because the increase in plastic strain at the crack tip and overload plastic zone size are larger in the plane-stress surface regions than in the plane-strain interior regions. These results are not entirely consistent with either of the proposed models.

  6. Surface Characterization of Carbon Fiber Polymer Composites and Aluminum Alloys After Laser Interference Structuring

    NASA Astrophysics Data System (ADS)

    Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian; Warren, Charles D.; Daniel, Claus

    2016-05-01

    The increasing use of carbon fiber-reinforced polymer matrix composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (1) structuring of the AL 5182 surface, (2) removal of the resin layer on top of carbon fibers, and (3) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg—T83 epoxy, 5 ply thick, 0°/90° plaques were used. The effects of laser fluence, scanning speed, and number of shots-per-spot were investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope imaging were used to study the effect of the laser processing on the surface morphology. It was found that an effective resin ablation and a low density of broken fibers for CFPC specimens was attained using laser fluences of 1-2 J/cm2 and number of 2-4 pulses per spot. A relatively large area of periodic line structures due to energy interference were formed on the aluminum surface at laser fluences of 12 J/cm2 and number of 4-6 pulses per spot.

  7. The Effect of Electric Current and Strain Rate on Serrated Flow of Sheet Aluminum Alloy 5754

    NASA Astrophysics Data System (ADS)

    Zhao, Kunmin; Fan, Rong; Wang, Limin

    2016-03-01

    Electrically assisted tensile tests are carried out on sheet aluminum alloy AA5754 at electric current densities ranging from 0 to 30.4 A/mm2 and strain rates ranging from 10-3 to 10-1 s-1. The strain rate sensitivity and the serrated flow behavior are investigated in accordance with dynamic strain aging mechanism. The strain rate sensitivity changes from negative to positive and keeps increasing with current density. The tendency toward serrated flow is characterized by the onset of Portevin-Le Chatelier (PLC) instabilities, which are influenced by strain rate, temperature, and electric current. The evolutions of three types of serrated flow are observed and analyzed with respect to strain rate and current density. The magnitude of serration varies with strain rate and current density. The serrated flow can be suppressed by a high strain rate, a high temperature, or a strong electric current. The threshold values of these parameters are determined and discussed. Conventional oven-heated tensile tests are conducted to distinguish the electroplasticity. The flow stress reduces more in electrically assisted tension compared to oven-heated tension at the same temperature level. The electric current helps suppress the serrated flow at the similar temperature level of oven-heating.

  8. Effects of V addition on recrystallization resistance of 7150 aluminum alloy after simulative hot deformation

    SciTech Connect

    Lai, Jing; Shi, Cangji; Chen, X.-Grant

    2014-10-15

    The effects of different V contents (0.01 to 0.19 wt.%) on the recrystallization resistance of 7150 aluminum alloys during post-deformation heat treatment were investigated. The microstructural evolutions at as-cast, as-homogenized conditions and after post-deformation annealing were studied using optical, scanning electron and transmission electron microscopes and using the electron backscattered diffraction technique. The precipitation of Al{sub 21}V{sub 2} dispersoids was observed in alloys containing 0.11 to 0.19 wt.% V after homogenization. The dispersoids were mainly distributed in the dendrite cells, and the precipitate-free zones occurred in the interdendritic regions and near grain boundaries. V addition could significantly enhance the recrystallization resistance during post-deformation annealing, particularly in the presence of a great number of Al{sub 21}V{sub 2} dispersoids. Recrystallized grain growth was effectively restricted because of the dispersoid pinning effect. The alloy containing 0.15 wt.% V exhibited the highest recrystallization resistance amongst all V-containing alloys studied. - Highlights: • Investigated the effect of V level on microstructure and flow stress of 7150 alloys • Characterized microstructures using optical microscopy, SEM, TEM and EBSD • Described the precipitation behavior of V-dispersoids in the dendritic structure • Studied the V effect on recrystallization resistance during post heat treatment • V addition greatly enhanced the recrystallization resistance during annealing.

  9. A method to study the history of a double oxide film defect in liquid aluminum alloys

    NASA Astrophysics Data System (ADS)

    Raiszadeh, R.; Griffiths, W. D.

    2006-12-01

    Entrained double oxide films have been held responsible for reductions in mechanical properties in aluminum casting alloys. However, their behavior in the liquid metal, once formed, has not been studied directly. It has been proposed that the atmosphere entrapped in the double oxide film defect will continue to react with the liquid metal surrounding it, perhaps leading to its elimination as a significant defect. A silicon-nitride rod with a hole in one end was plunged into liquid aluminum to hold a known volume of air in contact with the liquid metal at a constant temperature. The change in the air volume with time was recorded by real-time X-ray radiography to determine the reaction rates of the trapped atmosphere with the liquid aluminum, creating a model for the behavior of an entrained double oxide film defect. The results from this experiment showed that first oxygen, and then nitrogen, was consumed by the aluminum alloy, to form aluminum oxide and aluminum nitride, respectively. The effect of adding different elements to the liquid aluminum and the effect of different hydrogen contents were also studied.

  10. Hot deformation behavior of 7150 aluminum alloy during compression at elevated temperature

    SciTech Connect

    Jin Nengping; Zhang Hui; Han Yi; Wu Wenxiang; Chen Jianghua

    2009-06-15

    Hot compression tests of 7150 aluminum alloy were preformed on Gleeble-1500 system in the temperature range from 300 deg. C to 450 deg. C and at strain rate range from 0.01 s{sup -1} to 10 s{sup -1}, and the associated structural changes were studied by observations of metallographic and transmission electron microscope. The results show that the true stress-true strain curves exhibit a peak stress at a critical strain, after which the flow stresses decrease monotonically until high strains, showing a dynamic flow softening. The peak stress level decreases with increasing deformation temperature and decreasing strain rate, which can be represented by a Zener-Hollomon parameter in the hyperbolic-sine equation with the hot deformation activation energy of 229.75 kJ/mol. In the deformed structures appear the elongated grains with serrations developed in the grain boundaries, decreasing of Z value leads to more adequate proceeding of dynamic recrystallization and coarser recrystallized grains. The subgrains exhibit high-angle sub-boundaries with a certain amount of dislocations and large numbers of dynamic precipitates in subgrain interiors as increasing Z value. The dynamic recovery and recrystallization are the main reasons for the flow softening at low Z value, but the dynamic precipitates and successive dynamic particles coarsening have been assumed to be responsible for the flow softening at high Z value.

  11. CO2 laser beam welding of 6061-T6 aluminum alloy thin plate

    NASA Astrophysics Data System (ADS)

    Hirose, Akio; Kobayashi, Kojiro F.; Todaka, Hirotaka

    1997-12-01

    Laser beam welding is an attractive welding process for age-hardened aluminum alloys, because its low heat input minimizes the width of weld fusion and heat-affected zones (HAZs). In the present work, 1-mm-thick age-hardened Al-Mg-Si alloy, 6061-T6, plates were welded with full penetration using a 2.5-kW CO2 laser. Fractions of porosity in the fusion zones were less than 0.05 pct in bead-on-plate welding and less than 0.2 pct in butt welding with polishing the groove surface before welding. The width of a softened region in the-laser beam welds was less than 1/4 times that of a tungsten inert gas (TIG) weld. The softened region is caused by reversion of strengthening β″ (Mg2Si) precipitates due to weld heat input. The hardness values of the softened region in the laser beam welds were almost fully recovered to that of the base metal after an artificial aging treatment at 448 K for 28.8 ks without solution annealing, whereas those in the TIG weld were not recovered in a partly reverted region. Both the bead-on-plate weld and the butt weld after the postweld artificial aging treatment had almost equivalent tensile strengths to that of the base plate.

  12. Wrinkle Behavior of Hydroforming of Aluminum Alloy Double-Layer Sheets

    NASA Astrophysics Data System (ADS)

    Zhou, Bin-Jun; Xu, Yong-Chao

    2016-07-01

    In this article, the wrinkling behavior and thickness distribution of 5A06 aluminum alloy sheets in an annealed state with thickness of 1.0 mm and 2.5 mm was numerically and experimentally investigated under different hydraulic pressures in the hydroforming of single-layer and double-layer sheets. Note that, in double-layer sheets hydroforming, an upper-aided sheet is needed. The upper, thicker sheet synchronously deforms with the lower, thinner sheet during hydroforming. When the double-layer sheets are separated, a thinner curved sheet part will be manufactured. As can be seen from the simulation and experimental results, the upper, thicker sheet could effectively suppress the wrinkles of the lower, thinner sheet and improve the thickness distribution due to the increasing anti-wrinkle ability of the formed sheet and the interfacial friction between the double-layer sheets. In addition, the maximum hydraulic pressure can be decreased via hydroforming of double-layer sheets; this approach reduces the drawing force for large sheet parts and meets the requirement of energy conservation.

  13. The effects of pitting on fatigue crack nucleation in 7075-T6 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Ma, LI; Hoeppner, David W.

    1994-01-01

    A high-strength aluminum alloy, 7075-T6, was studied to quantitatively evaluate chemical pitting effects of its corrosion fatigue life. The study focused on pit nucleation, pit growth, and fatigue crack nucleation. Pitting corrosion fatigue experiments were conducted in 3.5 percent NaCl aqueous solution under constant amplitude sinusoidal loading at two frequencies, 5 and 20 Hz. Smooth and unnotched specimens were used in this investigation. A video recording system was developed to allow in situ observation of the surface changes of the specimens during testing. The results indicated that pitting corrosion considerably reduces the fatigue strength by accelerating fatigue crack nucleation. A metallographic examination was conducted on the specimens to evaluate the nature of corrosion pits. First, the actual shapes of the corrosion pits were evaluated by cross-sectioning the pits. Secondly, the relation between corrosion pits and microstructure was also investigated. Finally, the possibility of another corrosion mechanism that might be involved in pitting was explored in this investigation. The fractography of the tested specimens showed that corner corrosion pits were responsible for fatigue crack nucleation in the material due to the associated stress concentration. The pits exhibited variance of morphology. Fatigue life for the experimental conditions appeared to be strongly dependent on pitting kinetics and the crack nucleation stage.

  14. Enhanced pitting corrosion resistance of aluminum alloy 7075 in the presence of oxalate anions

    SciTech Connect

    Kobotiatis, L.; Tsikrikas, C.; Koutsoukos, P.G.

    1995-01-01

    The presence of oxalate in chloride-containing corrosive aqueous media was found to protect aluminum alloy AA 7075 (UNS A95075). The effect of 0.05 M sodium oxalate on induction times for the initiation of pit formation was measured on AA 7075 specimens. The variance and the mean value of the induction times measured increased with the time of specimen immersion at the open circuit potential (OCP). Statistical analysis was done by potentiostatic measurement of several specimens using electrochemical instrumentation controlled by a personal computer. Pit generation rates were found to be inversely proportional to the duration of the immersion period at OCP. Therefore, it was concluded that prolonged exposure of the tested specimens to sodium oxalate solutions enhanced their resistance to corrosion. Impedance measurements confirmed this finding. The increased resistance was attributed to the retardation of the process by which the surface protective layer would have been destroyed. This retardation may have been ascribable to the formation of surface complexes between Al{sup 3+} and oxalates from the bulk solution. Polarization of the specimens at anodic potentials reduced the corrosion resistance of AA 7075, possibly because of the destabilization of the surface complexes formed between Al and the oxalate ions.

  15. Effect of electrolyte volume on the acid dissolution of aluminum alloy 7075

    SciTech Connect

    McCafferty, E.

    1998-11-01

    Dissolution of aluminum alloy 7075 (UNS A97075) was studied using weight-loss measurements in a series of hydrochloric acid (HCl) solutions varying in concentration from 0.5 M to 2 M. The open-circuit reaction was observed to be first order in the hydrogen ion. In acid solutions having a fixed supply of hydrogen ions, corrosion of Al 7075 was arrested by depletion of that available supply. For a given initial acid molarity (M) and a given initial surface area, the total amount of corrosion (weight loss [G]) is given by G = 0.0101 V M, where V is the volume of solution. For a given set of conditions (initial acid concentration, initial surface area, and volume of solution), the time for cessation of the corrosion reaction as calculated from first-order reaction kinetics was in agreement with experimentally determined values. Two corrosion systems were discussed as possible applications involving cessation of a corrosion reaction in acid environments caused by depletion of the hydrogen ion supply.

  16. Stress corrosion cracking of an aluminum alloy used in external fixation devices.

    PubMed

    Cartner, Jacob L; Haggard, Warren O; Ong, Joo L; Bumgardner, Joel D

    2008-08-01

    Treatment for compound and/or comminuted fractures is frequently accomplished via external fixation. To achieve stability, the compositions of external fixators generally include aluminum alloy components due to their high strength-to-weight ratios. These alloys are particularly susceptible to corrosion in chloride environments. There have been several clinical cases of fixator failure in which corrosion was cited as a potential mechanism. The aim of this study was to evaluate the effects of physiological environments on the corrosion susceptibility of aluminum 7075-T6, since it is used in orthopedic external fixation devices. Electrochemical corrosion curves and alternate immersion stress corrosion cracking tests indicated aluminum 7075-T6 is susceptible to corrosive attack when placed in physiological environments. Pit initiated stress corrosion cracking was the primary form of alloy corrosion, and subsequent fracture, in this study. Anodization of the alloy provided a protective layer, but also caused a decrease in passivity ranges. These data suggest that once the anodization layer is disrupted, accelerated corrosion processes occur. PMID:18257055

  17. A Numerical Simulation for Dissimilar Aluminum Alloys Joined by Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Hamilton, Carter; Kopyściański, Mateusz; Węglowska, Aleksandra; Dymek, Stanisław; Pietras, Adam

    2016-09-01

    Dissimilar aluminum alloy sheets of 2017A-T451 and 7075-T651 (6 mm thickness) were friction stir welded in a butt weld configuration. A numerical simulation of the joining process was developed to visualize the material flow patterns and temperature distribution and to correlate the microstructure to the hardness behavior. Due to the complementary downward flow of surface material into the workpiece thickness and upward flow of mid-plane and bottom-plane material, the weld nugget is composed of alternating layers of 7075 and 2017A. These layers have unique temperature histories depending on the material's initial location within the cross section; therefore, they also have distinctive precipitate distributions. Supersaturated surface material flows into the process zone and forms a core in which GP zones reprecipitate upon cooling. Mid-plane and bottom-plane material flow toward the workpiece surface and encompass the surface material core. Within this region, the weld temperatures overage the equilibrium θ phase in 2017A, decreasing the hardness, and at the same time, dissolve the equilibrium η/ T phase in the 7075, leading to reprecipitation of GP zones upon cooling and a hardness recovery.

  18. Development of a New Ferrous Aluminosilicate Refractory Material for Investment Casting of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Yuan, Chen; Jones, Sam; Blackburn, Stuart

    2012-12-01

    Investment casting is a time-consuming, labour intensive process, which produces complex, high value-added components for a variety of specialised industries. Current environmental and economic pressures have resulted in a need for the industry to improve current casting quality, reduce manufacturing costs and explore new markets for the process. Alumino-silicate based refractories are commonly used as both filler and stucco materials for ceramic shell production. A new ceramic material, norite, is now being produced based on ferrous aluminosilicate chemistry, having many potential advantages when used for the production of shell molds for casting aluminum alloy. This paper details the results of a direct comparison made between the properties of a ceramic shell system produced with norite refractories and a typical standard refractory shell system commonly used in casting industry. A range of mechanical and physical properties of the systems was measured, and a full-scale industrial casting trial was also carried out. The unique properties of the norite shell system make it a promising alternative for casting aluminum based alloys in the investment foundry.

  19. Development of an Optimization Methodology for the Aluminum Alloy Wheel Casting Process

    NASA Astrophysics Data System (ADS)

    Duan, Jianglan; Reilly, Carl; Maijer, Daan M.; Cockcroft, Steve L.; Phillion, Andre B.

    2015-08-01

    An optimization methodology has been developed for the aluminum alloy wheel casting process. The methodology is focused on improving the timing of cooling processes in a die to achieve improved casting quality. This methodology utilizes (1) a casting process model, which was developed within the commercial finite element package, ABAQUS™—ABAQUS is a trademark of Dassault Systèms; (2) a Python-based results extraction procedure; and (3) a numerical optimization module from the open-source Python library, Scipy. To achieve optimal casting quality, a set of constraints have been defined to ensure directional solidification, and an objective function, based on the solidification cooling rates, has been defined to either maximize, or target a specific, cooling rate. The methodology has been applied to a series of casting and die geometries with different cooling system configurations, including a 2-D axisymmetric wheel and die assembly generated from a full-scale prototype wheel. The results show that, with properly defined constraint and objective functions, solidification conditions can be improved and optimal cooling conditions can be achieved leading to process productivity and product quality improvements.

  20. Development of Surfaces Optically Suitable for Flat Solar Panels

    NASA Technical Reports Server (NTRS)

    Desmet, D.; Jason, A.

    1978-01-01

    Three areas of research in the development of flat solar panels are described. (1) A reflectometer which can separately evaluate the spectral and diffuse reflectivities of surfaces was developed. The reflectometer has a phase locked detection system. (2) A coating composed of strongly bound copper oxide that is formed by an etching process performed on an aluminum alloy with high copper content was also developed. Because of this one step fabrication process, fabrication costs are expected to be small. (3) A literature search was conducted and conclusions on the required optical properties of flat plate solar collectors are presented.

  1. Flat growth of 7075, 7475, 7050 and 7049 aluminum alloy plate in stress corrosion environments: 2-year marine atmosphere results

    NASA Technical Reports Server (NTRS)

    Dorward, R. C.; Hasse, K. R.

    1978-01-01

    Marine atmospheric exposure of smooth and precracked specimens from 7075, 7475, 7050 and 7049 plates support the conclusion that for a given strength level, the short transverse stress corrosion resistance of 7050-T7X and 7049-T7X is superior to that of 7075-T7X. The threshold stress intensity (K sub Iscc) for these alloys is about 25 MPa square root m at a yield strength of about 460 MPa; the corresponding yield strength level for 7075-T7X at this SCR level is about 425 MPa. Additional tests on two lots of high-toughness 7475 plate indicate that this alloy is capable of achieving K sub Iscc values of about 35 MPa square root m at yield strengths of 400-450 MPa. Precracked specimens from all these 7XXX-series alloys are subject to self loading from corrosion product wedging. This effect causes stress corrosion cracks to continue growing at very low apparent stress intensities, and should therefore be considered a potential driving force for stress corrosion in design and materials selection.

  2. Cast Aluminum Alloys for High Temperature Applications Using Nanoparticles Al2O3 and Al3-X Compounds (X = Ti, V, Zr)

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2009-01-01

    In this paper, the effect of nanoparticles Al2O3 and Al3-X compounds (X = Ti, V, Zr) on the improvement of mechanical properties of aluminum alloys for elevated temperature applications is presented. These nanoparticles were selected based on their low cost, chemical stability and low diffusions rates in aluminum at high temperatures. The strengthening mechanism at high temperature for aluminum alloy is based on the mechanical blocking of dislocation movements by these nanoparticles. For Al2O3 nanoparticles, the test samples were prepared from special Al2O3 preforms, which were produced using ceramic injection molding process and then pressure infiltrated by molten aluminum. In another method, Al2O3 nanoparticles can also be homogeneously mixed with fine aluminum powder and consolidated into test samples through hot pressing and sintering. With the Al3-X nanoparticles, the test samples are produced as precipitates from in-situ reactions with molten aluminum using conventional permanent mold or die casting techniques. It is found that cast aluminum alloy using nanoparticles Al3-X is the most cost effective method to produce high strength aluminum alloys for high temperature applications in comparison to nanoparticles Al2O3. Furthermore, significant mechanical properties retention in high temperature environment could be achieved with Al3-X nanoparticles, resulting in tensile strength of nearly 3 times higher than most 300- series conventional cast aluminum alloys tested at 600 F.

  3. Effect of Frequency, Environment, and Temperature on Fatigue Behavior of E319 Cast Aluminum Alloy: Stress-Controlled Fatigue Life Response

    NASA Astrophysics Data System (ADS)

    Zhu, X.; Jones, J. W.; Allison, J. E.

    2008-11-01

    The fatigue stress-life (S-N) behavior of E319 cast aluminum alloy was studied by using both ultrasonic and conventional fatigue techniques in order to understand the potential effect of frequency on fatigue behavior of cast aluminum alloys. It was observed that, at the investigated temperature (20 °C, 150 °C, and 250 °C), fatigue life in air at 20 kHz is 5 to 10 times longer than that at 75 Hz. The difference in fatigue life between 20 kHz and 75 Hz is attributable to an environmental effect on fatigue crack growth rate. The effect of frequency, environment, and temperature on S-N behavior of E319 cast aluminum alloy can be predicted by use of a general version of a modified environmental superposition model. Environmental effects need to be considered when ultrasonic fatigue is used for estimating fatigue lives of aluminum alloys that are under cyclic loading at lower frequencies in service. It is possible to extrapolate ultrasonic fatigue data to conventional fatigue behavior for an E319 cast aluminum alloy based on the environmental superposition model.

  4. The effects of microstructure on MIC susceptibility in high strength aluminum alloys

    SciTech Connect

    Walsh, D.W.

    1999-11-01

    Aluminum alloys, and in particular Al-Li-Cu alloys are attractive to the aerospace industry. The high specific strength and stiffness of these alloys will improve lift efficiency, fuel economy, performance and increase payload capabilities of air and spacecraft. The objectives of this work were to examine the corrosion behavior of Al 2195 (UNS A92195) (Al-4Cu-1Li) and to assess the effect of welding on corrosion behavior in biologically active and in sterile waters. Al 2219 (UNS A922 19) samples were used in parallel tests to provide a baseline for the data generated. In this study samples were exposed to mild corrosive water solutions in both the as received and as welded conditions. The results of the study indicate exposure to biologically active solutions increases the corrosion rate. In addition, welding increases the corrosion rate in both Al 2195 and Al 2219, and causes severe localization in Al 2195. Furthermore, autogenously welded Al 2195 samples were more susceptible to attack than heterogeneously welded Al 2195 samples. Heterogeneously welded samples in both materials also had high corrosion rates, but only the Al 2195 material was subject to localization of attack. The partially melted zones of Al 2195 samples were subject to severe, focused attack. In Al 2219, interdendritic constituents in welded areas and intergranular constituents in base material were cathodic to the Al rich matrix materials. In Al 2195, some interdendritic constituents in welded areas and intergranular constituents in base material were anodic to the Al rich matrix materials. Corrosion resistance was correlated to material microstructure using optical microscopy, scanning electron microscopy, electron probe microanalysis and polarization resistance.

  5. High strain rate superplasticity in three contrasting fine grained aluminum alloys

    SciTech Connect

    Todd, R.I.; Kim, J.S.; Zahid, G.H.; Prangnell, P.B.

    2000-07-01

    The superplastic properties and microstructures of three contrasting fine grained aluminum alloys were investigated. These included (1) a powder metallurgy MMC, (2) a severely deformed spray cast alloy, and (3) the Zn-22% Al eutectoid alloy. The results showed some differences in the details of behavior between the alloys. One of these was the presence of true work hardening, associated with dislocation activity, in the MMC, and its absence in the microduplex Zn-Al eutectoid alloy. In addition, the powder route MMC had the high threshold stress (up to 10 MPa) commonly encountered in such materials, whereas this was not the case with the cast and severely deformed alloy, indicating that the threshold stress was associated with the presence of ceramic particles in the MMC (oxide + reinforcement). In all the alloys, however, the m value tended to increase with temperature, and this led to a corresponding increase in elongation with temperature until the microstructure became destabilized. In the two predominantly single phase alloys studied this destabilization corresponded to the solvus temperature. The constantly changing m value indicates that there is no unique value of this parameter. The same was found to be true of the grain size exponent, p. The direct interpretation of apparent activation energies in terms of simple physical processes should be made with care in the light of the present results, as (1) the microstructures of two of the alloys were found to change continuously and significantly with small changes in temperature, and (2) the fact that m is a function of temperature necessarily implies that the apparent activation energy is a function of stress.

  6. Effect of Thermal Exposure on the Tensile Properties of Aluminum Alloys for Elevated Temperature Service

    NASA Technical Reports Server (NTRS)

    Edahl, Robert A., Jr.; Domack, Marcia

    2004-01-01

    Tensile properties were evaluated for four aluminum alloys that are candidates for airframe applications on high speed transport aircraft. These alloys included the Al-Cu-Mg-Ag alloys C415 and C416 and the Al-Cu-Li-Mg-Ag alloys RX818 and ML377. The Al-Cu-Mg alloys CM001, which was used on the Concorde SST, and 1143, which was modified from the alloy used on the TU144 Russian supersonic aircraft, were tested for comparison. The alloys were subjected to thermal exposure at 200 F, 225 F and 275 F for times up to 30,000 hours. Tensile tests were performed on thermally-exposed and as-received material at -65 F, room temperature, 200 F, 225 F and 275 F. All four candidate alloys showed significant tensile property improvements over CM001 and 1143. Room temperature yield strengths of the candidate alloys were at least 20% greater than for CM001 and 1143, for both the as-received and thermally-exposed conditions. The strength levels of alloy RX818 were the highest of all materials investigated, and were 5-10% higher than for ML377, C415 and C416 for the as-received condition and after 5,000 hours thermal exposure. RX818 was removed from this study after 5,000 hours exposure due to poor fracture toughness performance observed in a parallel study. After 30,000 hours exposure at 200 F and 225 F, the alloys C415, C416 and ML377 showed minor decreases in yield strength, tensile strength and elongation when compared to the as-received properties. Reductions in tensile strength from the as-received values were up to 25% for alloys C415, C416 and ML377 after 15,000 hours exposure at 275 F.

  7. Characteristics and treatability of oil-bearing wastes from aluminum alloy machining operations.

    PubMed

    Chen, Luke; Hsieh, Chueh-Chen; Wetherbee, John; Yang, Chen-Lu

    2008-04-15

    Enomoto Industry Co., exclusively uses water-based cutting fluids in its aluminum alloy machining operations. Since the cost of disposal can be much greater than the cost of purchase, the treatability of spent cutting fluids is becoming a major criterion for cutting fluid selection. Samples were collected from the machining lines at Enomoto's facility to determine their characteristics and evaluate their treatability with centrifugation, chemical coagulation and electrochemical coagulation. As expected, oil and grease (O&G) and total suspended solids (TSS) are the main reasons that spent cutting fluids are prohibited from being discharged into local swage systems. The average O&G found in the spent cutting fluids is 87,354 mg/L with TSS of more than 70,000 mg/L. Both O&G and TSS are the major contributors to the high turbidity of these waste effluents. A centrifuge with a relative centrifugal force of 1318 x g, was able to reduce 60% of the turbidity. By adding the coagulant aluminum chloride, the oil-water emulsion was destabilized, and the turbidity was reduced from 3249 Formazin Attenuation Units (FAU) to around 314 FAU. With freshly generated aluminum ions in the spent cutting fluid, the electrochemical process destabilized the oil-water emulsion system. The coalesced oil droplets were adsorbed onto the highly dispersed aluminum coagulant. The oil-rich sludge that was generated in the operation was then floated to the surface, forming a blanket that was removed by skimming. The electrochemical treatment was able to reduce the turbidity to less than 14 FAU, which is the detection limit of the Hach DR/4000 UV-vis spectrophotometer. PMID:17850956

  8. Microstructure Analysis of Directionally Solidified Aluminum Alloy Aboard the International Space Station

    NASA Astrophysics Data System (ADS)

    Angart, Samuel Gilbert

    This thesis entails a detailed microstructure analysis of directionally solidified (DS) Al-7Si alloys processed in microgravity aboard the International Space Station and similar duplicate ground based experiments at Cleveland State University. In recent years, the European Space Agency (ESA) has conducted experiments on alloy solidification in microgravity. NASA and ESA have collaborated for three DS experiments with Al- 7 wt. % Si alloy, aboard the International Space Station (ISS) denoted as MICAST6, MICAST7 and MICAST12. The first two experiments were processed on the ISS in 2009 and 2010. MICAST12 was processed aboard the ISS in the spring of 2014; the resulting experimental results of MICAST12 are not discussed in this thesis. The primary goal of the thesis was to understand the effect of convection in primary dendrite arm spacings (PDAS) and radial macrosegregation within DS aluminum alloys. The MICAST experiments were processed with various solidification speeds and thermal gradients to produce alloy with differences in microstructure features. PDAS and radial macrosegregation were measured in the solidified ingot that developed during the transition from one solidification speed to another. To represent PDAS in DS alloy in the presence of no convection, the Hunt-Lu model was used to represent diffusion-controlled growth. By sectioning cross-sections throughout the entire length of solidified samples, PDAS was measured and calculated. The ground-based (1-g) experiments done at Cleveland State University CSU were also analyzed for comparison to the ISS experiments (0-g). During steady state in the microgravity environment, there was a reasonable agreement between the measured and calculated PDAS. In ground-based experiments, transverse sections exhibited obvious radial macrosegregation caused by thermosolutal convection resulting in a non-agreement with the Hunt-Lu model. Using a combination of image processing techniques and Electron Microprobe Analysis

  9. Identification of modes of fracture in a 2618-T6 aluminum alloy using stereophotogrammetry

    SciTech Connect

    Salas Zamarripa, A.; Mata, M.P. Guerrero; Morales, M. Castillo; Beber-Solano, T.P.

    2011-12-15

    The identification and the development of a quantification technique of the modes of fracture in fatigue fracture surfaces of a 2618-T6 aluminum alloy were developed during this research. Fatigue tests at room and high temperature (230 Degree-Sign C) were carried out to be able to compare the microscopic fractographic features developed by this material under these testing conditions. The overall observations by scanning electron microscopy (SEM) of the fracture surfaces showed a mixture of transgranular and ductile intergranular fracture. The ductile intergranular fracture contribution appears to be more significant at room temperature than at 230 Degree-Sign C. A quantitative methodology was developed to identify and to measure the contribution of these microscopic fractographic features. The technique consisted of a combination of stereophotogrammetry and image analysis. Stereo-pairs were randomly taken along the crack paths and were then analyzed using the profile module of MeX software. The analysis involved the 3-D surface reconstruction, the trace of primary profile lines in both vertical and horizontal directions within the stereo-pair area, the measurements of the contribution of the modes of fracture in each profile, and finally, the calculation of the average contribution in each stereo-pair. The technique results confirmed a higher contribution of ductile intergranular fracture at room temperature than at 230 Degree-Sign C. Moreover, there was no indication of a direct relationship between this contribution and the strain amplitudes range applied during the fatigue testing. - Highlights: Black-Right-Pointing-Pointer Stereophotogrammetry and image analysis as a measuring tool of modes of fracture in fatigue fracture surfaces. Black-Right-Pointing-Pointer A mixture of ductile intergranular and transgranular fracture was identified at room temperature and 230 Degree-Sign C testing. Black-Right-Pointing-Pointer Development of a quantitative methodology to

  10. Microstructural characterization of aluminum alloys using Weck's reagent, part I: Applications

    SciTech Connect

    Gao, Li; Harada, Yohei; Kumai, Shinji

    2015-09-15

    This paper focuses on the applications of a color etchant for aluminum alloys named Weck's reagent. The Al phase shows different colors from location to location after being etched by Weck's reagent. It is proved that Weck's reagent is very sensitive to the micro-segregations of Ti, Si and Mg in Al alloys so that characterization of the micro-segregations can be qualitatively realized which is usually done by electronic probe techniques. With the help of this characterization method, we are able to evaluate solid fractions for the semi-solid processed Al alloy with a better accuracy by excluding the Al grain growth during water quenching. To understand this reagent better, the color change during etching is investigated by applying different etching times at room temperature (25 °C). Among those results, 12 s shows the best color contrast after etching. Finally, we repeat the 12 second etching for four times through repeating a polishing–etching process. The result exhibits that Weck's reagent has a satisfying re-producibility with stable color and color distribution for the four times etching result. The second part of this study covers the coloring mechanism of Weck's reagent by characterizing the etched surface via various characterization methods. - Highlights: • The applications of Weck's reagent for Al alloys are introduced in detail. • Detailed relationship between micro-segregations in Al phase and the color difference revealed by Weck's reagent are studied. • Etching time has a strong influence on the color revealed by Weck's reagent. • Besides micro-segregation, grain boundaries can also be visualized by Weck's reagent, which was proved by EBSD analysis.

  11. Characterization of Molybdate Conversion Coatings for Aluminum Alloys by Electrochemical Impedance Spectroscopy

    NASA Technical Reports Server (NTRS)

    Calle, Luz Marina

    2000-01-01

    Electrochemical impedance spectroscopy (EIS) was used to investigate the corrosion inhibiting properties of newly developed proprietary molybdate conversion coatings on aluminum alloy 2024-T3 under immersion in aerated 5% (w/w) NaCl. Corrosion potential and EIS measurements were gathered for six formulations of the coating at several immersion times for two weeks. Nyquist as well as Bode plots of the data were obtained. The conversion-coated alloy panels showed an increase in the corrosion potential during the first 24 hours of immersion that later subsided and approached a steady value. Corrosion potential measurements indicated that formulations A, D, and F exhibit a protective effect on aluminum 2024-T3. The EIS spectra of the conversion-coated alloy were characterized by an impedance that is higher than the impedance of the bare alloy at all the immersion times. The low frequency impedance, Z(sub lf) (determined from the value at 0.05 Hz) for the conversion-coated alloy was higher at all the immersion times than that of the bare panel. This indicates improvement of corrosion resistance with addition of the molybdate conversion coating. Scanning electron microscopy (SEM) revealed the presence of cracks in the coating and the presence of cubic crystals believed to be calcium carbonate. Energy dispersive spectroscopy (EDS) of the test panels revealed the presence of high levels of aluminum, oxygen, and calcium but did not detect the presence of molybdenum on the test panels. X-ray photoelectron spectroscopy (XPS) indicated the presence of less than 0.01 atomic percent molybdenum on the surface of the coating.

  12. Hydrogen Embrittlement Susceptibility and Hydrogen-Induced Additive Stress of 7050 Aluminum Alloy Under Various Aging States

    NASA Astrophysics Data System (ADS)

    Qi, W. J.; Song, R. G.; Qi, X.; Li, H.; Wang, Z. X.; Wang, C.; Jin, J. R.

    2015-09-01

    Hydrogen embrittlement susceptibility of 7050 aluminum alloy under various aging states has been investigated by means of cathodic hydrogen permeation, slow strain rate test, hydrogen determinator, x-ray diffraction, and scanning electron microscope, and effect of hydrogen on atomic binding force of charged alloy has been calculated by free electron theory in this paper. Simultaneously, hydrogen-induced additive stress (σad) of 7050 aluminum alloy hydrogen charged with different current densities under various aging states have been investigated by flowing stress differential method. The results showed that hydrogen concentration of examined alloy increased with increasing charging time or current density under the same aging state. Hydrogen segregation occurred at grain boundaries which enlarged the crystal lattice constant, meanwhile, it reduced the average bonding energy and interatomic bonding force of the grain boundary atoms, thus resulting in hydrogen embrittlement; moreover, σad of 7050 aluminum alloy increased linearly with increasing hydrogen concentration under the same aging state, i.e., under aged: σad = -1.61 + 9.93 × 105 C H, peak aged: σad = -1.55 + 9.67 × 105 C H, over aged: σad = -0.16 + 9.35 × 105 C H, correspondingly, σad increased the susceptibility to hydrogen embrittlement ( I HE) further. Under the same charging condition, aging states had a great influence on σad and I HE, the under-aged state alloy was of the highest, the over-aged state alloy was of the lowest, and peak-aged was in the middle.

  13. Analysis and Comparison of Aluminum Alloy Welded Joints Between Metal Inert Gas Welding and Tungsten Inert Gas Welding

    NASA Astrophysics Data System (ADS)

    Zhao, Lei; Guan, Yingchun; Wang, Qiang; Cong, Baoqiang; Qi, Bojin

    2015-09-01

    Surface contamination usually occurs during welding processing and it affects the welds quality largely. However, the formation of such contaminants has seldom been studied. Effort was made to study the contaminants caused by metal inert gas (MIG) welding and tungsten inert gas (TIG) welding processes of aluminum alloy, respectively. SEM, FTIR and XPS analysis was carried out to investigate the microstructure as well as surface chemistry. These contaminants were found to be mainly consisting of Al2O3, MgO, carbide and chromium complexes. The difference of contaminants between MIG and TIG welds was further examined. In addition, method to minimize these contaminants was proposed.

  14. Overload and Underload Effects on the Fatigue Crack Growth Behavior of the 2024-T3 Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Dawicke, David S.

    1997-01-01

    Fatigue crack growth tests were conducted on 0.09 inch thick, 3.0 inch wide middle-crack tension specimens cut from sheets of 2024-T3 aluminum alloy. The tests were conducted using a load sequence that consisted of a single block of 2,500 cycles of constant amplitude loading followed by an overload/underload combination. The largest fatigue crack growth life occurred for the tests with the overload stress equal to 2 times the constant amplitude stress and the underload stress equal to the constant amplitude minimum stress. For the tests with compressive underloads, the fatigue crack growth life decreased with increasing compressive underload stress.

  15. The Role of Entrained Surface Oxides in RS-PM Aluminum Alloys on Resultant Structures and Properties

    NASA Technical Reports Server (NTRS)

    Grant, N. J.

    1985-01-01

    The RS-PM aluminum alloys which show less than anticipated toughness properties were studied. After eliminating negative variables such as sodium and potassium in lithium containing alloys, hydrogen in all Al alloys, and trapped impurities from the atomization processing the data pointed to fine oxides, as the primary cause of poor toughness properties. The oxide content of aluminum powders increases with: decreasing powder size, deviations from spherical powder shapes, exposure to moist atmospheres either during atomization or in subsequent powder handling, and alloy compositions which contain significant amounts of lithium, magnesium, cerium, and other reactive elements.

  16. A study of environmental characterization of conventional and advanced aluminum alloys for selection and design. Phase 1: Literature review

    NASA Technical Reports Server (NTRS)

    Sprowls, D. O.

    1984-01-01

    A review of the literature is presented with the objectives of identifying relationships between various accelerated stress corrosion testing techniques, and for determining the combination of test methods best suited to selection and design of high strength aluminum alloys. The following areas are reviewed: status of stress-corrosion test standards, the influence of mechanical and environmental factors on stress corrosion testing, correlation of accelerated test data with in-service experience, and procedures used to avoid stress corrosion problems in service. Promising areas for further work are identified.

  17. Effects of environmental variables on the crack initiation stages of corrosion fatigue of high strength aluminum alloys

    NASA Technical Reports Server (NTRS)

    Poteat, L. E.

    1981-01-01

    Fatigue initiation in six aluminum alloys used in the aircraft industry was investigated. Cyclic loading superimposed on a constant stress was alternated with atmospheric corrosion. Tests made at different stress levels revealed that a residual stress as low as 39% of the yield strength caused stress corrosion cracking in some of the alloys. An atmospheric corrosion rate meter developed to measure the corrosivity of the atmosphere is described. An easily duplicated hole in the square test specimen with a self-induced residual stress was developed.

  18. Local melting and tool slippage during friction stir spot welding of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Gerlich, Adrian Piotr

    Local melting and tool slippage during friction stir spot welding of different aluminum alloys is examined using a combination of detailed microscopy and temperature measurement. It has been widely accepted that friction stir welding is a solid-state process and does not involve melting. The present research indicates that local melting is an inherent feature when Al 7075 and Al 2024 alloys are spot welded, and produces tool slippage at the tool contact interface. In contrast, intermetallic particles contained in the Al 5754 and Al 6061 as-received materials do not melt and a no-slip condition is maintained. A combination of data acquisition of key welding parameters (axial force, torque and tool displacement), high-speed imaging, temperature measurement and metallography are employed to study the tool penetration stage and the subsequent dwell period during spot welding. A methodology is developed for reliably determining the stir zone temperature using thermocouples embedded within the tool itself. Tool slippage is investigated by determining the strain rate in stir zone material adjacent to the rotating tool. The strain rate is estimated by substituting stir zone temperature and subgrain size measurements into the Zener-Hollomon equation. Tool penetration early in the friction stir spot welding process can be explained as a progression of wear events from mild (delamination) wear, through to severe wear, and finally to melt wear in the material located immediately under the tip of the rotating pin. The stir zone peak temperature during welding is limited by either the solidus temperature of the alloy in question, or by local melting of intermetallic particles contained in the base material such as Al 7075 or Al 2024 alloys. Melted films dissolve rapidly in the high temperature stir zone, and as the weld cools to room temperature. Metallographic evidence confirming local melting and cracking is observed in Al 7075 and Al 2024 alloy friction stir spot welds made

  19. Development of a nanoscale precipitation-strengthened creep-resistant aluminum alloy containing trialuminide precipitates

    NASA Astrophysics Data System (ADS)

    Knipling, Keith Edward

    This research is toward developing a castable and heat-treatable precipitation-strengthened aluminum alloy exhibiting coarsening- and creep resistance at temperatures exceeding 400°C. Criteria for selecting alloying elements capable of producing such an alloy are established. Those systems forming Al3M trialuminide compounds with a cubic L12 crystal structure are favored, and based on a review of the existing literature, these are assessed in terms of solid-solubility and diffusivity in alpha-Al(satisfying the need for slow coarsening kinetics), and castability (which is discussed based on the binary phase diagrams). The first Group 3 element, Sc, and the second Group 4 element, Zr, are shown to be most promising. These expectations are confirmed by an initial study on the Al-Ti system, which demonstrates that conventionally-solidified alloys are not capable of precipitation strengthening. The Al-Zr system, by contrast, exhibits precipitation of nanometer-scale Al3Zr (L12) producing pronounced precipitation hardening when aged at 375, 400, or 425°C. The Al3 Zr precipitates are coarsening resistant and have the metastable L1 2 structure up to 500°C, a result of very sluggish diffusion of Zr in alpha-Al. Ternary additions of Ti are also investigated, forming Al 3(Zr1-xTix) (L12) precipitates with a reduced lattice parameter mismatch with alpha-Al, potentially improving the coarsening resistance. The composition of Al3(Zr1-xTi x) precipitates formed at 375 or 425°C are measured directly using 3-D atom-probe tomography. At these temperatures, the Zr:Ti atomic ratio in the precipitates is about 10 and 5, respectively, indicating that most of the available Ti fails to partition to the Al3(Zr1- xTix) phase. This is consistent with prior studies on Al-Sc alloys, where the slower-diffusing ternary solute species make up a small fraction of the Al3Sc-based precipitates. Despite the confirmed presence of Ti, Al3(Zr1- xTix) precipitates exhibit no improvement in terms of

  20. Microplastic bases for constitutive characterization of aluminum alloys and their correlation to sheet formability

    NASA Astrophysics Data System (ADS)

    Diak, Bradley James

    correlate to formability were assessed. Detailed experimental evidence is given for different aluminum alloys containing mainly fast or slow diffusing solute species, transition precipitates, dispersed particles, and/or dislocation debris. These systems of Al-Fe, Al-Cr, Al-Cu, Al-Mg, and Al-Mg-Si, all displayed unique dislocation-defect interactions which could be elucidated by the current theory of thermally activated flow.