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Sample records for 7075-t6 aluminum alloys

  1. Crack Initiation and Growth Behavior at Corrosion Pit in 7075-T6 High Strength Aluminum Alloy

    DTIC Science & Technology

    2013-06-01

    CRACK INITIATION AND GROWTH BEHAVIOR AT CORROSION PIT IN 7075-T6 HIGH STRENGTH ALUMINUM ALLOY THESIS Eric M. Hunt, Second Lieutenant, USAF AFIT-ENY...7075-T6 HIGH STRENGTH ALUMINUM ALLOY THESIS Presented to the Faculty Department of Aerospace and Astronautical Engineering Graduate School of Engineering...RELEASE; DISTRIBUTION UNLIMITED AFIT-ENY-13-J-01 CRACK INITIATION AND GROWTH BEHAVIOR AT CORROSION PIT IN 7075-T6 HIGH STRENGTH ALUMINUM ALLOY Eric M

  2. Deformation behavior and microstructural evolution of 7075-T6 aluminum alloy at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Lee, Woei-Shyan; Lin, Ching-Rong

    2016-10-01

    The impact deformation behavior and associated microstructural evolution of 7075-T6 aluminum alloy at cryogenic temperatures are investigated using a compressive split-Hopkinson pressure bar (SHPB) system. Cylindrical specimens are deformed at strain rates of 1 × 103 s-1, 2 × 103 s-1, 3 × 103 s-1 and 5 × 103 s-1 and temperatures of 0 °C, -100 °C and -196 °C. It is shown that the flow stress is strongly dependent on the strain rate and temperature. For a given temperature, the flow stress varies with the strain rate in accordance with a power law relation with an average exponent of 0.157 and an activation energy of 0.7 kJ/mol. Moreover, the coupled effects of the strain rate and temperature on the flow stress are adequately described by the Zener-Hollomon parameter (Z). For all test temperatures, catastrophic failure occurs only under the highest strain rate of 5 × 103 s-1, and is the result of adiabatic shear. An increasing strain rate or reducing temperature leads to a greater dislocation density and a smaller grain size. Finally, the dependence of the flow stress on the microstructural properties of the impacted 7075-T6 specimens is well described by a specific Hall-Petch constitutive model with constants of K = 108.3 MPa μm1/2 and K‧ = 16.1 MPa μm, respectively. Overall, the results presented in this study provide a useful insight into the combined effects of strain rate and temperature on the flow resistance and deformability of 7075-T6 alloy and confirm that 7075-T6 is well suited to the fabrication of fuel tanks and related structural components in the aerospace field.

  3. Chemically short-crack behavior of the 7075-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Dolley, Evan Jarrett, Jr.

    Commercial and military aircraft are exposed to deleterious environments (such as salt spray) that can enhance the fatigue-crack-growth (FCG) rates in structural components. This phenomenon, generically termed corrosion fatigue (CF) can have a large effect on their fatigue lives. CFCG behavior may be separated into two regimes: a chemically long-crack regime and a chemically short-crack regime. FCG rates in the chemically long-crack regime for the 7075-T6 aluminum alloy are approximately one order of magnitude greater than those in a dehumidified environment and exhibit growth rate similitude under a constant crack driving force ( D K). FCG rates in the chemically short-crack regime exhibit a breakdown in growth rate similitude at crack lengths shorter than 7 mm. The growth rates at 0.5 mm are 2 times greater than those in the long-crack regime and decay with increasing crack length to the long-crack rates at approximately 7 mm. The extent of the chemically short-crack behavior in the 7075-T6 aluminum alloy depends on D K, crack length and dissolved oxygen concentration in the aqueous solution. Mathematical modeling of the mass transport of dissolved oxygen to the crack tip region shows a good correlation between the chemically short-crack behavior and the amount of dissolved oxygen at the crack tip. The short-crack behavior is not observed in a deaerated solution. The enhanced growth rates are caused by hydrogen embrittlement. Fracture in dehumidified air occurs along the 100 fracture plane while cracking in the chemically short and long-crack regimes occur on 100 and 110 (flat brittle type fracture) planes with the fractional area of the 110 fracture decreasing with increasing crack length in the chemically short-crack regime. Predicted and actual FCG rates correlate well showing that the enhancement of growth rates in the deleterious environment depends on the amount of 110 fracture. The chemically short-crack behavior may reduce the FCG life of a structure by

  4. 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.

  5. Effect of specimen thickness of fatigue-crack-growth behavior and fracture toughness of 7075-T6 and 7178-T6 aluminum alloys

    NASA Technical Reports Server (NTRS)

    Hudson, C. M.; Newman, J. C., Jr.

    1973-01-01

    A study was made to determine the effects of specimen thickness on fatigue crack growth and fracture behavior of 7075-T6 and 7178-T6 aluminum alloy sheet and plate. Specimen thicknesses ranged from 5.1 to 12.7 mm (0.20 to 0.50 in.) for 7075-T6 and from 1.3 to 6.4 mm (0.05 to 0.25 in.) for 7178-T6. The stress ratios R used in the crack growth experiments were 0.02 and 0.50. For 7075-T6, specimen thickness had relatively little effect on fatigue-crack growth. However, the fracture toughness of the thickness of the thickest gage of 7075-T6 was about two-thirds of the fracture toughness of the thinner gages of 7075-T6. For 7178-T6, fatigue cracks generally grew somewhat faster in the thicker gages than in the thinnest gage. The fracture toughness of the thickest gage of 7178-T6 was about two-thirds of the fracture toughness of the thinner gages of 7178-T6. Stress intensity methods were used to analyze the experimental results. For a given thickness and value of R, the rate of fatigue crack growth was essentially a single-valued function of the stress intensity range for 7075-T6 and 7178-T6. An empirical equation developed by Forman, Kearney, and Engle fit the 7075-T6 and 7178-T6 crack growth data reasonably well.

  6. A study of fatigue and fracture in 7075-T6 aluminum alloy in vacuum and air environments

    NASA Technical Reports Server (NTRS)

    Hudson, C. M.

    1973-01-01

    Axial load fatigue life, fatigue-crack propagation, and fracture toughness experiments were conducted on sheet specimens made of 7075-T6 aluminum alloy. These experiments were conducted at pressures ranging from atmospheric to 5 x 10 to the minus 8th torr. Analysis of the results from the fatigue life experiments indicated that for a given stress level, lower air pressures produced longer fatigue lives. At a pressure of 5 x 10 to the minus 8th torr fatigue lives were 15 or more times as long as at atmospheric pressure. Analysis of the results from the fatigue crack propagation experiments indicated that for small stress intensity factor ranges the fatigue crack propagation rates were up to twice as high at atmospheric pressure as in vacuum. The fracture toughness of 7075-T6 was unaffected by the vacuum environment. Fractographic examination showed that specimens tested in both vacuum and air developed fatigue striations. Considerably more striations developed on specimens tested at atmospheric pressure, however.

  7. Effect of service usage on tensile, fatigue, and fracture properties of 7075-T6 and 7178-T6 aluminum alloys

    NASA Technical Reports Server (NTRS)

    Everett, R. A., Jr.

    1975-01-01

    A study has been made to determine the effects of extensive service usage on some basic material properties of 7075-T6 and 7178-T6 aluminum alloy materials. The effects of service usage were determined by comparing material properties for new material (generally obtained from the literature) with those for material cut from the center wing box of a C-130B transport airplane with 6385 flight-hours of service. The properties investigated were notched and unnotched fatigue strengths, fatigue-crack-growth rate, fracture toughness, and tensile properties. For the properties investigated and the parameter ranges considered (crack length, stress ratio, etc.), the results obtained showed no significant difference between service and new materials.

  8. Artificial neural networks application for modeling of friction stir welding effects on mechanical properties of 7075-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Maleki, E.

    2015-12-01

    Friction stir welding (FSW) is a relatively new solid-state joining technique that is widely adopted in manufacturing and industry fields to join different metallic alloys that are hard to weld by conventional fusion welding. Friction stir welding is a very complex process comprising several highly coupled physical phenomena. The complex geometry of some kinds of joints makes it difficult to develop an overall governing equations system for theoretical behavior analyse of the friction stir welded joints. Weld quality is predominantly affected by welding effective parameters, and the experiments are often time consuming and costly. On the other hand, employing artificial intelligence (AI) systems such as artificial neural networks (ANNs) as an efficient approach to solve the science and engineering problems is considerable. In present study modeling of FSW effective parameters by ANNs is investigated. To train the networks, experimental test results on thirty AA-7075-T6 specimens are considered, and the networks are developed based on back propagation (BP) algorithm. ANNs testing are carried out using different experimental data that they are not used during networks training. In this paper, rotational speed of tool, welding speed, axial force, shoulder diameter, pin diameter and tool hardness are regarded as inputs of the ANNs. Yield strength, tensile strength, notch-tensile strength and hardness of welding zone are gathered as outputs of neural networks. According to the obtained results, predicted values for the hardness of welding zone, yield strength, tensile strength and notch-tensile strength have the least mean relative error (MRE), respectively. Comparison of the predicted and the experimental results confirms that the networks are adjusted carefully, and the ANN can be used for modeling of FSW effective parameters.

  9. A transmission electron microscopy study of constituent-particle-induced corrosion in 7075-T6 and 2024-T3 aluminum alloys

    SciTech Connect

    Wei, R.P.; Liao, C.M.; Gao, M.

    1998-04-01

    To better understand particle-induced pitting corrosion in aluminum alloys, thin foil specimens of 7075-T6 and 2024-T3 aluminum alloys, with identified constituent particles, were immersed in aerated 0.5M NaCl solution and then examined by transmission electron microscopy (TEM). The results clearly showed matrix dissolution around the iron- and manganese-containing particles (such as Al{sub 23}CuFe{sub 4}), as well as the Al{sub 2}Cu particles. While Al{sub 2}CuMg particles tended to dissolve relative to the matrix, limited local dissolution of the matrix was also observed around these particles. These results are consistent with scanning electron microscopy (SEM) observations of pitting corrosion and are discussed in terms of the electrochemical characteristics of the particles and the matrix.

  10. Determination of the dynamic stress intensity factors for 7075-T6 aluminum alloy using the reflected caustic method

    SciTech Connect

    Tsukagoshi, Seiji; Takahashi, Susumu; Shimamoto, Akira

    1996-12-31

    Dynamic fracture initiation and propagation in Al 7075-T6 was investigated experimentally using the optical method of reflected caustics combined with a simplified high speed photography. A crack propagation testing configuration consisting of a three point bending specimen loaded In a drop weighting was used. It was found that prior to crack initiation the stress intensity factor time record calculated using the dynamic impact load and a static formula disagrees with the actual stress Intensity factor measured by caustics. The impact fracture tests are performed. With use of Al 7075-T6 band plate test specimens with a V-notch on their one side. The dynamic stress intensity factor K{sub id} are given. With this, the authors experimentally calculated the dynamic fracture toughness K{sub ID}.

  11. Prediction of low-cycle fatigue-life by acoustic emission—1: 2024-T3 aluminum alloy, and —2: 7075-T6 aluminum alloy

    SciTech Connect

    Baram, J.; Rosen, M.

    1981-01-01

    1: In this paper, low-cycle fatigue tests were conducted by tension-tension until rupture, on a 2024-T3 aluminum alloy sheet. Initial crack sizes and orientations in the fatigue specimens were found to be randomly distributed. Acoustic emission was continuously monitored during the tests. Every few hundred cycles, the acoustic signal having the highest peak-amplitude, was recorded as an extremal event for the elapsed period. This high peak-amplitude is related to a fast crack propagation rate through a phenomenological relationship. The extremal peak amplitudes are shown by an ordered statistics treatment, to be extremally distributed. The statistical treatment enables the prediction of the number of cycles left until failure. Predictions performed a posteriori based on results gained early in each fatigue test are in good agreement with actual fatigue lives. Finally, the amplitude distribution analysis of the acoustic signals emitted during cyclic stress appears to be a promising nondestructive method of predicting fatigue life. 2: In this paper, low cycle high stress fatigue tests were conducted by tension-tension on an Alclad 7075-T6 aluminum sheet alloy, until rupture. Initial crack sizes and orientations in the fatigue specimens were randomly distributed. Acoustic emission was continuously monitored during the tests. Extremal peak-amplitudes, equivalent to extremal crack-propagation rates, are shown to be extremally Weibull distributed. The prediction of the number of cycles left until failure is made possible, using an ordered statistics treatment and an experimental equipment parameter obtained in previous experiments (Part 1). The predicted life-times are in good agreement with the actual fatigue lives. Finally, the amplitude distribution analysis of the acoustic signals emitted during cyclic stress has been proven to be a feasible nondestructive method of predicting fatigue life.

  12. Study of mechanical joint strength of aluminum alloy 7075-T6 and dual phase steel 980 welded by friction bit joining and weld-bonding under corrosion medium

    SciTech Connect

    Lim, Yong Chae; Squires, Lile; Pan, Tsung-Yu; Miles, Michael; Song, Guang-Ling; Wang, Yanli; Feng, Zhili

    2014-12-30

    We have employed a unique solid-sate joining process, called friction bit joining (FBJ), to spot weld aluminum alloy (AA) 7075-T6 and dual phase (DP) 980 steel. Static joint strength was studied in the lap shear tension configuration. In addition, weld-bonding (adhesive + FBJ) joints were studied in order to evaluate the ability of adhesive to mitigate the impact of corrosion on joint properties. Accelerated laboratory cyclic corrosion tests were carried out for both FBJ only and weld-bonding joints. Furthermore, the FBJ only joints that emerged from corrosion testing had lap shear failure loads that were significantly lower than freshly prepared joints. However, weld-bonding specimens retained more than 80% of the lap shear failure load of the freshly prepared weld-bonding specimens. Moreover, examination of joint cross sections confirmed that the presence of adhesive in the weld-bonding joints mitigated the effect of the corrosion environment, compared to FBJ only joints.

  13. A damage tolerance comparison of 7075-T6 aluminum alloy and IM7/977-2 carbon/epoxy

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.; Lance, David G.; Hodge, Andrew J.

    1991-01-01

    A comparison of low velocity impact damage between one of the strongest aluminum alloys, to a new, damage tolerant resin system as a matrix for high strength carbon fibers was examined in this study. The aluminum and composite materials were used as face sheets on a 0.13 g/cu cm aluminum honeycomb. Four levels of impact energy were used; 2.6 J, 5.3 J, 7.8 J and 9.9 J. The beams were compared for static strength and fatique life by use of the four-point bend flexure test. It was found that in the undamaged state the specific strength of the composite face sheets was about twice that of the aluminum face sheets. A sharp drop in strength was observed for the composite specimens impacted at the lowest (2.6J) energy level, but the overall specific strength was still higher than for the aluminum specimens. At all impact energy levels tested, the static specific strength of the composite face sheets were significantly higher than the aluminum face sheets. The fatigue life of the most severely damaged composite specimen was about 17 times greater than the undamaged aluminum specimens when cycled at 1 Hz between 20 percent and 85 percent of ultimate breaking load.

  14. Critical assessment of precracked specimen configuration and experimental test variables for stress corrosion testing of 7075-T6 aluminum alloy plate

    NASA Technical Reports Server (NTRS)

    Domack, M. S.

    1985-01-01

    A research program was conducted to critically assess the effects of precracked specimen configuration, stress intensity solutions, compliance relationships and other experimental test variables for stress corrosion testing of 7075-T6 aluminum alloy plate. Modified compact and double beam wedge-loaded specimens were tested and analyzed to determine the threshold stress intensity factor and stress corrosion crack growth rate. Stress intensity solutions and experimentally determined compliance relationships were developed and compared with other solutions available in the literature. Crack growth data suggests that more effective crack length measurement techniques are necessary to better characterize stress corrosion crack growth. Final load determined by specimen reloading and by compliance did not correlate well, and was considered a major source of interlaboratory variability. Test duration must be determined systematically, accounting for crack length measurement resolution, time for crack arrest, and experimental interferences. This work was conducted as part of a round robin program sponsored by ASTM committees G1.06 and E24.04 to develop a standard test method for stress corrosion testing using precracked specimens.

  15. Study of mechanical joint strength of aluminum alloy 7075-T6 and dual phase steel 980 welded by friction bit joining and weld-bonding under corrosion medium

    DOE PAGES

    Lim, Yong Chae; Squires, Lile; Pan, Tsung-Yu; ...

    2014-12-30

    We have employed a unique solid-sate joining process, called friction bit joining (FBJ), to spot weld aluminum alloy (AA) 7075-T6 and dual phase (DP) 980 steel. Static joint strength was studied in the lap shear tension configuration. In addition, weld-bonding (adhesive + FBJ) joints were studied in order to evaluate the ability of adhesive to mitigate the impact of corrosion on joint properties. Accelerated laboratory cyclic corrosion tests were carried out for both FBJ only and weld-bonding joints. Furthermore, the FBJ only joints that emerged from corrosion testing had lap shear failure loads that were significantly lower than freshly preparedmore » joints. However, weld-bonding specimens retained more than 80% of the lap shear failure load of the freshly prepared weld-bonding specimens. Moreover, examination of joint cross sections confirmed that the presence of adhesive in the weld-bonding joints mitigated the effect of the corrosion environment, compared to FBJ only joints.« less

  16. Effect of Welding Parameters on Microstructure, Thermal, and Mechanical Properties of Friction-Stir Welded Joints of AA7075-T6 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Lotfi, Amir Hossein; Nourouzi, Salman

    2014-06-01

    A high-strength Al-Zn-Mg-Cu alloy AA7075-T6 was friction-stir welded with various process parameter combinations incorporating the design of the experiment to investigate the effect of welding parameters on the microstructure and mechanical properties. A three-factors, five-level central composition design (CCD) has been used to minimize the number of experimental conditions. The friction-stir welding parameters have significant influence on the heat input and temperature profile, which in turn regulates the microstructural and mechanical properties of the joints. The weld thermal cycles and transverse distribution of microhardness of the weld joints were measured, and the tensile properties were tested. The fracture surfaces of tensile specimens were observed by a scanning electron microscope (SEM), and the formation of friction-stir processing zone has been analyzed macroscopically. Also, an equation was derived to predict the final microhardness and tensile properties of the joints, and statistical tools are used to develop the relationships. The results show that the peak temperature during welding of all the joints was up to 713 K (440 °C), which indicates the key role of the tool shoulder diameter in deciding the maximum temperature. From this investigation, it was found that the joint fabricated at a rotational speed of 1050 rpm, welding speed of 100 mm/min, and shoulder diameter of 14 mm exhibited higher mechanical properties compared to the other fabricated joints.

  17. An Experimental Investigation of the Effects of Vacuum Environment on the Fatigue Life, Fatigue-Crack-Growth Behavior, and Fracture Toughness of 7075-T6 Aluminum Alloy. Ph.D. Thesis - North Carolina State Univ.

    NASA Technical Reports Server (NTRS)

    Hudson, C. M.

    1972-01-01

    Axial load fatigue life, fatigue-crack propagation, and fracture toughness tests were conducted on 0.090-inch thick specimens made of 7075-T6 aluminum alloy. The fatigue life and fatigue-crack propagation experiments were conducted at a stress ratio of 0.02. Maximum stresses ranged from 33 to 60 ksi in the fatigue life experiments, and from 10 to 40 ksi in the fatigue-crack propagation experiments, and fatigue life experiments were conducted at gas pressures of 760, 0.5, 0.05, and 0.00000005 torr. Fatigue-crack-growth and fracture toughness experiments were conducted at gas pressures of 760 and 5 x 10 to the minus 8th power torr. Residual stress measurements were made on selected fatigue life specimens to determine the effect of such stresses on fatigue life. Analysis of the results from the fatigue life experiments indicated that fatigue life progressively increased as the gas pressure decreased. Analysis of the results from the fatigue-crack-growth experiments indicates that at low values of stress-intensity range, the fatigue crack growth rates were approximately twice as high in air as in vacuum. Fracture toughness data showed there was essentially no difference in the fracture toughness of 7075-T6 in vacuum and in air.

  18. Early state damage detection of aluminum 7075-T6 plate based on acoustic emission

    NASA Astrophysics Data System (ADS)

    Ozevin, Didem; Li, Zhong; Heidary, Zahra

    2011-04-01

    Aluminum alloy 7075-T6 is a commonly used material in aircraft industry. A crack usually initiates at the edge of a fastener hole, and it can affect the maintenance schedule and reduce the life of an aircraft structure significantly. The fatigue property of the material has been researched widely to develop methods and models for predicting fatigue crack growth under random loading. From the point of damage tolerance design, the inspection technique of a crack for an aircraft structure is very important because it can be used to determine the inspection period of the aircraft structure. The acoustic emission (AE) technique is a nondestructive testing (NDT) method that is able to monitor damage initiation and progression in real time. Understanding the early stage of AE signature due to the damage progression using small scale laboratory samples requires non-traditional data analysis approaches. In this study, 1mm thick Al-7075-T6 plates were tested under monotonic and fatigue loading. The initiation of damage progression using AE data was identified based on improved linear location algorithm and the result was verified using elasto-plastic finite element model. The improved location algorithm integrates dispersive characteristics of flexural waves and threshold independent approach to pick up the wave arrival time. In this paper, AE results in comparison with FE model under monotonic and fatigue loading will be presented. The comparison of traditional and improved location approaches will be shown. The approach for implementing the laboratory scale results in the large scale field testing will be discussed.

  19. Ratcheting fatigue behaviour of Al-7075 T6 alloy: Influence of stress parameters

    NASA Astrophysics Data System (ADS)

    Amarnath, Lala; Bhattacharjee, Antara; Dutta, K.

    2016-02-01

    The use of aluminium and aluminium based alloys are increasing rapidly on account of its high formability, good thermal and electrical conductivity, high strength and lightness. Aluminium alloys are extensively used in aerospace, automobile, marine and space research industries and are also put into structural applications where chances of fatigue damage cannot be ruled out. In the current work, it is intended to study the ratcheting fatigue behavior of 7075-T6 aluminium alloy at room temperature. This Al alloy is potentially used in aviation, marine and automotive components as well as in bicycle parts, rock mounting equipment and parts of ammunition where there is every chance of failure of the parts due to deformation caused by ratcheting. Ratcheting is the process of accruement of plastic stain produced when a component is subjected to asymmetric cyclic loading under the influence of low cycle fatigue. To accomplish the requirements of the projected research, stress-controlled cyclic loading experiments were done using a ±250 kN servo-hydraulic universal testing machine (Instron: 8800R). The effect of stress parameters such as mean stress and stress amplitude were investigated on the ratcheting behavior of the selected aluminium alloy. It was observed that, ratcheting strain increased with increase in the value of stress amplitude at any constant mean stress while a saturation in strain accumulation attained in the investigated material after around 10-20 cycles, under all test conditions. The analyses of hysteresis loop generated during cyclic loading indicate that the material exhibits cyclic hardening in the initial fifty cycles which gets softened in further loading up to about 70-80 cycles and finally attains a steady state. The increase in the ratcheting strain value with stress parameters happens owing to increased deformation domain during cycling. The cyclic hardening accompanied by softening is correlated with characteristic precipitation features of

  20. Fatigue Strengths of Aircraft Materials: Axial-Load Fatigue Tests on Edge-Notched Sheet Specimens of 2024-T3 and 7075-T6 Aluminum Alloys and of SAE 4130 Steel with Notch Radii of 0.004 and 0.070 inch

    NASA Technical Reports Server (NTRS)

    Grover, H. J.; Hyler, W. S.; Jackson, L. R.

    1959-01-01

    The present report gives results of axial-load fatigue tests on notched specimens of three sheet materials: 2024-T3 and 7075-T6 aluminum alloys and normalized SAE 4130 steel. Two edge-notched specimens were designed and tested, each having a theoretical stress-concentration factor K(sub t) = 4.0. The radii of the notches were 0.004 and 0.070 inch. Tests of these specimens were run at two levels of nominal mean stress: 0 and 20,000 psi. Results of these studies extended information previously reported on tests of specimens with varying notch severity. They afford data on the variation of fatigue-strength reduction with notch radius and on the potential usefulness of Neuber's technical stress-concentration factor K(sub n).

  1. Electrochemical investigation on the hydrogen permeation behavior of 7075-T6 Al alloy and its influence on stress corrosion cracking

    NASA Astrophysics Data System (ADS)

    Zheng, Chuan-bo; Yan, Bing-hao; Zhang, Ke; Yi, Guo

    2015-07-01

    The hydrogen permeation behavior and stress corrosion cracking (SCC) susceptibility of precharged 7075-T6 Al alloy were investigated in this paper. Devanthan-Stachurski (D-S) cell tests were used to measure the apparent hydrogen diffusivity and hydrogen permeation current density of specimens immersed in 3.5wt% NaCl solution. Electrochemical experiment results show that the SCC susceptibility is low during anodic polarization. Both corrosion pits and hydrogen-induced cracking are evident in scanning electron microscope images after the specimens have been charging for 24 h.

  2. An analytical electron microscopy study of constituent particles in commercial 7075-T6 and 2024-T3 alloys

    SciTech Connect

    Gao, M.; Feng, C.R.; Wei, R.P.

    1998-04-01

    To better understand the role of constituent particles in pitting corrosion, analytical electron microscopic studies were performed on the constituent particles in commercial 7075-T6 and 2024-T3 alloys. Five phases, namely, Al{sub 23}CuFe{sub 4} and amorphous SiO{sub 2} in 7075-T6 and Al{sub 2}CuMg, Al{sub 2}Cu, and (Fe,Mn){sub x}Si(Al,Cu){sub y} in 2024-T3, were identified. The crystal structure and chemistry of the Al{sub 23}CuFe{sub 4}, Al{sub 2}CuMg, and Al{sub 2}Cu phases in these alloys are in good agreement with the published data. Small deviations from their stoichiometric compositions were observed and are attributed to the influence of alloy composition on the phase chemistry. For the (Fe,Mn){sub x}Si(Al,Cu){sub y} (approximately, x = 3 and y = 11) phase, a rhombohedral structure, with lattice parameter a = b = c = 1.598 nm and {alpha} = {beta} = {gamma} = 75 deg, was identified and is believed to be a modified form of either Al{sub 8}Fe{sub 2}Si or Al{sub 10}Mn{sub 3}Si. Information from this study provided technical support for studying the electrochemical interactions between the individual particles (or phases) and the matrix. The corrosion results are reported in a companion article.

  3. Residual strength of cracked 7075 T6 Al-alloy sheets under high loading rates

    NASA Astrophysics Data System (ADS)

    Vasek, A.; Schijve, J.

    1995-04-01

    Dynamic tests were carried out on long sheet specimens with two collinear cracks. First the ligament between the two cracks fails, which implies that the cracks are linked up to a single crack. Linking up did increase the loading rate (dK/dt) of the outer crack tips up to 2 x 10(exp 4) MPa (sq root) m/s. COD measurements during the fast running crack were made. The residual strength was decreased by about 10 percent as compared to the quasi-static result. Fractographic evidence indicates that a high dK/dt has some effect on the shear lips. It promotes some plane-strain influence, associated with an increased yield stress, due to the high plastic strain rate in the crack tip zone. The results were evaluated in terms of fracture mechanics. The results are bearing on the damage tolerance of aircraft structures built up from 7075-T6 sheet material.

  4. Effect of shot peening and grain refinement on the fatigue life and strength of commercially pure Al and two of its alloys: Al-2024-T3 and Al-7075-T6

    NASA Astrophysics Data System (ADS)

    Qandil, A.; Zaid, Adnan I. O.

    2016-08-01

    Aluminum and its alloys are widely used materials in automobile, aircraft and space craft industries due to their high strength- to- weight ratio and corrosion resistance beside their other useful properties. They are the second materials in use after steel alloys. Most of the failures in parts of aircrafts and space vehicles are mainly caused by fatigue and stress corrosion cracking. In this paper, the effect of shot peening on the fatigue life of commercially pure aluminumand two of its alloys namely:Al-2024 and Al-7075-T6 is presented and discussed. Furthermore, the effect of addition of vanadium to Al and Al grain refined by Ti and Ti+Bon Its fatigue life and strengthis also presented and discussed using scanning electron microscope, SEM. It was that shot peening and the addition of V toAl and Al onAl grain refined by Ti and Ti+B have resulted in enhancement of the fatigue life and strength. Ffinally, the effect of shot peening on the surface quality of the peened parts is also presented and discussed.

  5. Constitutive Model Constants for Al7075-T651 and Al7075-T6

    NASA Astrophysics Data System (ADS)

    Brar, Nachhatter; Joshi, Vasant; Harris, Bryan

    2009-06-01

    Aluminum 7075-T651 and 7075-T6 are characterized at quasi-static and high strain rates to determine Johnson-Cook (J-C) strength and fracture model constants. Constitutive model constants are required as input to computer codes to simulate projectile (fragment) impact or similar impact events on structural components made of these material. J-C strength model constants (A, B, n, C, and m) for the two alloys are determined from tension stress-strain data at room and high temperature to 250^oC. J-C strength model constants for Al7075-T651 are: A=527 MPa, B=676 MPa, n=0.71, C=0.017, and m=1.61 and for Al7075-T6: A = 546 MPa, B = 674 MPa, n = 0.72, C = 0.059, and m =1.56. J-C fracture model constants are determined form quasi-static and high strain rate/high temperature tests on notched and smooth tension specimens. J-C fracture model constants for the two alloys are: Al7075-T651; D1 = 0.110, D2 = 0.573, D3= -3.4446, D4 = 0.016, and D 5= 1.099 and Al7075-T6; D1= 0.451 D2= -0.952 D3= -.068, D4 =0.036, and D5 = 0.697.

  6. 7075-T6 and 2024-T351 Aluminum Alloy Fatigue Crack Growth Rate Data

    NASA Technical Reports Server (NTRS)

    Forth, Scott C.; Wright, Christopher W.; Johnston, William M., Jr.

    2005-01-01

    Experimental test procedures for the development of fatigue crack growth rate data has been standardized by the American Society for Testing and Materials. Over the past 30 years several gradual changes have been made to the standard without rigorous assessment of the affect these changes have on the precision or variability of the data generated. Therefore, the ASTM committee on fatigue crack growth has initiated an international round robin test program to assess the precision and variability of test results generated using the standard E647-00. Crack growth rate data presented in this report, in support of the ASTM roundrobin, shows excellent precision and repeatability.

  7. Corrosion Behavior of SiC Reinforced Aluminum Alloys

    DTIC Science & Technology

    1987-09-25

    observed for AA- 7075 -T6. Microscopic examination of the sur- faces showed that pitting behavior was nearly identical to that observed for the 6061...of the MMC was a dark grey which may indicate that the surface oxide was thicker. The anodic behavior of SiC/AA- 7075 -T6 and AA- 7075 -T6 sug- gested...m-- - osION BEHAVIOR OF SIC REINFORCED ALUMINUM ALLOYS (N) 0 BY J. F. MulNTYRE A. H. LE . GOLLEDGE R. CONRAD RESEARCH AND TECHNOLOGY DEPARTMENT 25

  8. Constitutive Model Constants for Al7075-T651 and Al7075-T6

    NASA Astrophysics Data System (ADS)

    Brar, N. S.; Joshi, V. S.; Harris, B. W.

    2009-12-01

    Aluminum 7075-T651 and 7075-T6 are characterized at quasi-static and high strain rates to determine Johnson-Cook (J-C) strength and fracture model constants. Constitutive model constants are required as input to computer codes to simulate projectile (fragment) impact or similar impact events on structural components made of these materials. Although the two tempers show similar elongation at breakage, the ultimate tensile strength of T651 temper is generally lower than the T6 temper. Johnson-Cook strength model constants (A, B, n, C, and m) for the two alloys are determined from high strain rate tension stress-strain data at room and high temperature to 250°C. The Johnson-Cook fracture model constants are determined from quasi-static and medium strain rate as well as high temperature tests on notched and smooth tension specimens. Although the J-C strength model constants are similar, the fracture model constants show wide variations. Details of the experimental method used and the results for the two alloys are presented.

  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. Environmentally assisted crack growth rates of high-strength aluminum alloys

    NASA Astrophysics Data System (ADS)

    Connolly, Brain J.; Deffenbaugh, Kristen L.; Moran, Angela L.; Koul, Michelle G.

    2003-01-01

    The scope of this project is to evaluate the environmentally assisted long crack growth behavior of candidate high-strength aluminum alloys/tempers, specifically AA7150-T7751 and AA7040-T7651, for consideration as viable replacements/refurbishment for stress-corrosion cracking in susceptible AA7075-T6 aircraft components found in aging aircraft systems.

  11. Effect of the layer of anodized 7075-T6 aluminium corrosion properties

    NASA Astrophysics Data System (ADS)

    Montoya Z, R. D.; L, E. Vera; Pineda T, Y.; Cedeño, M. L.

    2017-01-01

    Aluminium alloys are widely used in various sectors of industry. The 7075-T6 alloy corresponding to an Al-Zn T6, is mostly used as structural component in the aviation industry, due to the good relationship between weight and mechanical properties. However, the negative point of this alloys is the resistance to corrosion, which is why they need to be coated with an anodic film. Different surface treatments, such as anodizing, are used to improve corrosion resistance. Anodizing is an electrolytic process by which a protective layer on aluminium known as “alumina” is formed, this is formed by the passage of an electric current in an acidic electrolyte. This investigation presents a study of the effect of the thickness of layers of alumina deposited by anodized method, in the corrosion resistance of 7075-T6 aluminium. This study was performed by using in a solution of tartaric acid - sulfuric acid and an inorganic salt. To evaluate the influence alumina layer thickness on the corrosion properties some tests were carried out by using the electrochemical spectroscopy impedances (EIS) technique and Tafel polarization curves. It was found that the grown of the thickness of film favourably influences in the corrosion resistance.

  12. Characterization of Retrogression and Re-Aging Heat Treatment of AA7075-T6 Using Nonlinear Acoustics and Eddy Current

    SciTech Connect

    Ananthula, Rajeshwar; Ko, Ray T.; Sathish, Shamachary; Blodgett, Mark

    2004-02-26

    Nonlinear acoustic parameter and eddy current methods have been utilized to characterize the heat treatment process of retrogression and re-aging of aluminum 7075-T6. The results of nonlinear acoustic parameter measurements show two distinct peaks at 30 minutes and 45 minutes of retrogression time. The phase of the through-thickness eddy current signal shows a minimum at 42 minutes of retrogression time. Application of combined methods for identifying the optimized properties in the material is discussed.

  13. Investigation of the effect of vacuum environment on the fatigue and fracture behavior of 7075-T6.

    NASA Technical Reports Server (NTRS)

    Hudson, C. M.

    1972-01-01

    Axial-load fatigue-life, fatigue-crack propagation, and fracture-toughness experiments were conducted on sheet specimens made of 7075-T6 aluminum alloy. These experiments were conducted at air pressures ranging from 101 kN/sq m to 7 micronewtons/sq m to determine the effect of air pressure on fatigue behavior. Analysis of the results from the fatigue-life experiments indicated that for a given stress level, the lower the air pressure was the longer the fatigue life. At a pressure of 7 micronewtons/sq m, fatigue lives were 15 to 30 times longer than at 101 kN/sq m. Analysis of the results from the fatigue-crack-growth experiments indicates that at low values of stress-intensity range, the fatigue-crack-growth rates were approximately twice as high at atmospheric pressure as in vacuum. However, at higher values of stress-intensity range, the fatigue-crack-growth rates were nominally the same in vacuum and at atmospheric pressure.

  14. Experimental Investigation of Effects of Random Loading on the Fatigue Life of Notched Cantilever-Beam Specimens of 7075-T6 Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Fralich, Robert W.

    1959-01-01

    Results of random-loading fatigue tests on 125 notched cantilever-beam specimens and constant-amplitude fatigue tests on 46 similar specimens are presented in terms of the root-mean-square value of peak stresses. The results from the two sets of tests are compared on the basis of time to failure, where the results from the constant-amplitude tests are expressed in terms of an equivalent time to failure based on the natural period of vibration. Compared on this basis, failure at the lower stress levels occurred in a shorter time for the random loading than for the constant-amplitude loading, whereas at the higher stress levels failure occurred in the reverse order. A theoretical result for random loading is also presented and compared with the experimental results. The theoretical result shows good agreement with experiment for low values of stress but underestimates the time to failure at the higher stresses.

  15. Microstructure and Mechanical Behavior of Al 7075-T6 Subjected to Shallow Cryogenic Treatment

    NASA Astrophysics Data System (ADS)

    Mohan, K.; Suresh, J. A.; Ramu, Palaniappan; Jayaganthan, R.

    2016-06-01

    The effect of shallow cryogenic treatment (SCT) on the microstructure and mechanical properties of Al7075-T6 is investigated in the present work. The alloy was subjected to shallow CT at -80 °C for 72 h. Mechanical tests such as Vickers hardness test, tensile, and fatigue tests were performed on both native and treated samples. It was observed that the mechanical properties such as hardness, yield strength, and ultimate tensile strength increased by about 30, 17, and 7%, respectively, for the treated sample. The treated alloy was characterized by using the techniques such as optical microscopy, electron back scattered diffraction (EBSD), energy-dispersive x-ray spectroscopy (EDS), and transmission electron microscopy (TEM) to observe the changes in the microstructural features. EBSD results show precipitation, better distribution of second-phase particles, and higher dislocation density in the treated alloy as compared to the untreated alloy. The treatment imparts improved hardness and strength to the alloy due to precipitation hardening and high dislocation density. Fracture morphologies of the treated and the native samples were characterized by using scanning electron microscopy and it was observed that the striations were denser in the treated sample justifying the higher fatigue strength.

  16. Mechanical properties of dissimilar metal joints composed of DP 980 steel and AA 7075-T6

    DOE PAGES

    Squires, Lile; Lim, Yong Chae; Miles, Michael; ...

    2015-03-18

    In this study, a solid state joining process, called friction bit joining, was used to spot weld aluminium alloy 7075-T6 to dual phase 980 steel. Lap shear failure loads for specimens without adhesive averaged ~10kN, while cross-tension specimens averaged 2·8 kN. Addition of adhesive with a thickness up to 500 μm provided a gain of ~50% to lap shear failure loads, while a much thinner layer of adhesive increased cross-tension failure loads by 20%. Microstructures of the welds were martensitic, but the hardness of the joining bit portion was greater than that of the DP 980, owing to its highermore » alloy content. Softening in the heat affected zone of a welded joint appeared to be relatively small, though it was enough to cause nugget pullout failures in some lap shear tension specimens. Finally, other failures in lap shear tension were interfacial, while all of the failures in cross-tension were interfacial.« less

  17. Mechanical properties of dissimilar metal joints composed of DP 980 steel and AA 7075-T6

    SciTech Connect

    Squires, Lile; Lim, Yong Chae; Miles, Michael; Feng, Zhili

    2015-03-18

    In this study, a solid state joining process, called friction bit joining, was used to spot weld aluminium alloy 7075-T6 to dual phase 980 steel. Lap shear failure loads for specimens without adhesive averaged ~10kN, while cross-tension specimens averaged 2·8 kN. Addition of adhesive with a thickness up to 500 μm provided a gain of ~50% to lap shear failure loads, while a much thinner layer of adhesive increased cross-tension failure loads by 20%. Microstructures of the welds were martensitic, but the hardness of the joining bit portion was greater than that of the DP 980, owing to its higher alloy content. Softening in the heat affected zone of a welded joint appeared to be relatively small, though it was enough to cause nugget pullout failures in some lap shear tension specimens. Finally, other failures in lap shear tension were interfacial, while all of the failures in cross-tension were interfacial.

  18. Corrosion Fatigue Crack Growth Behavior at Notched Hole in 7075-T6 Under Biaxial and Uniaxial Fatigue with Different Phases

    DTIC Science & Technology

    2015-09-17

    CORROSION FATIGUE CRACK GROWTH BEHAVIOR AT NOTCHED HOLE IN 7075-T6 UNDER BIAXIAL AND UNIAXIAL FATIGUE WITH DIFFERENT PHASES...CORROSION FATIGUE CRACK GROWTH BEHAVIOR AT NOTCHED HOLE IN 7075-T6 UNDER BIAXIAL AND UNIAXIAL FATIGUE WITH DIFFERENT PHASES THESIS...UNLIMITED AFIT-ENY-MS-15-S-065 CORROSION FATIGUE CRACK GROWTH BEHAVIOR AT NOTCHED HOLE IN 7075-T6 UNDER BIAXIAL AND UNIAXIAL FATIGUE WITH

  19. Improved thermal treatment of aluminum alloy 7075

    NASA Technical Reports Server (NTRS)

    Cocks, F. H.

    1968-01-01

    Newly developed tempering treatment considerably increases the corrosion resistance of 7075-T6 alloy and concomitantly preserves its yield strength. The results of tests on samples of the alloy subjected to the above treatments show that when the overaging period is 12 hours /at 325 degrees F/, the alloy exhibits a yield strength of 73,000 psi.

  20. Parametric studies on tensile strength in joining AA6061- T6 and AA7075-T6 by gas metal arc welding process

    NASA Astrophysics Data System (ADS)

    Ishak, M.; Noordin, N. F. M.; Shah, L. H.

    2015-12-01

    Proper selection of the welding parameters can result in better joining. In this study, the effects of various welding parameters on tensile strength in joining dissimilar aluminum alloys AA6061-T6 and AA7075-T6 were investigated. 2 mm thick samples of both base metals were welded by semi-automatic gas metal arc welding (GMAW) using filler wire ER5356. The welding current, arc voltage and welding speed were chosen as variables parameters. The strength of each specimen after the welding operations were tested and the effects of these parameters on tensile strength were identified by using Taguchi method. The range of parameter for welding current were chosen from 100 to 115 A, arc voltage from 17 to 20 V and welding speed from 2 to 5 mm/s. L16 orthogonal array was used to obtained 16 runs of experiments. It was found that the highest tensile strength (194.34 MPa) was obtained with the combination of a welding current of 115 A, welding voltage of 18 V and welding speed of 4 mm/s. Through analysis of variance (ANOVA), the welding voltage was the most effected parameter on tensile strength with percentage of contribution at 41.30%.

  1. 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.

  2. Corrosion behavior of aluminum-lithium alloys

    SciTech Connect

    Garrard, W.N. )

    1994-03-01

    Corrosion behavior of three aluminum-lithium (Al-Li) alloys was investigated in aerated 0.5 M sodium sulfate (Na[sub 2]SO[sub 4]), deaerated 3.5% sodium chloride (NaCl), and aerated 3.5% NaCl. Corrosion behavior of the Aluminum Association (AA) alloys 2090-T8E41 (UNS A92090, sheet), AA 8090-T851 (UNS A98090, sheet), and AA 8090-T82551 (UNS A98090, bar) was compared to behavior of the conventional AA 7075-T6 (UNS A97075, sheet). Uniform corrosion was the predominant form of attack in aerated Na[sub 2]SO[sub 4] and deaerated NaCl, although some localized attack resulted from corrosion of intermetallics on specimen surfaces. Pitting was the main form of attack in aerated NaCl. In all three media, the sheet materials corroded at a similar rate, but the bar form of AA 8090 corroded at a lower rate. Pretreatment of the alloys by immersion in a cerium (Ce) solution inhibited pitting in aerated NaCl but only for a short period.

  3. 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.

  4. Chromium-free conversion coatings based on inorganic salts (Zr/Ti/Mn/Mo) for aluminum alloys used in aircraft applications

    NASA Astrophysics Data System (ADS)

    Santa Coloma, P.; Izagirre, U.; Belaustegi, Y.; Jorcin, J. B.; Cano, F. J.; Lapeña, N.

    2015-08-01

    Novel chromium-free conversion coatings based on Zr/Ti/Mn/Mo compounds were developed at a pilot scale to improve the corrosion resistance of the AA2024-T3 and AA7075-T6 aluminum alloys for aircraft applications. The influence of the presence of Zr and Ti in the Zr/Ti/Mn/Mo conversion bath's formulation on the corrosion resistance of the coated alloys was investigated. The corrosion resistance provided by the conversion coatings was evaluated by salt spray exposure and potentiodynamic sweeps. Optical and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and atomic force microscopy (AFM) operating in the Kelvin Probe mode (SKPFM) were used to provide microstructural information of the coated samples that achieved the best results in the corrosion tests. The salt spray test evidenced the higher corrosion resistance of the coated samples compared to the bare surfaces for both alloys. The potentiodynamic tests showed that the corrosion current density decreased for coated AA7075-T6 and AA2024-T3 alloys, which indicated an obvious improvement of the corrosion resistance with all the processes for both alloys. Although the corrosion resistance of the coated samples appeared to be higher for the alloy AA7075-T6 than for the alloy AA2024-T3, both alloys achieved the best corrosion protection with the coatings deposited from conversion bath formulations containing no titanium salts. The microscopy analysis on the coated AA7075-T6 samples revealed that a local deposition of Zr compounds and, possibly, an oxidation process occurred in the vicinity of the alloy's intermetallic particles. The amount of the Zr deposits at these locations increased with coating's formulations without Ti, which provided the best corrosion resistance. The Cr-free conversion coatings developed in this study for the AA7075-T6 and AA2024-T3 alloys do not meet yet the strict requirements of the aircraft industry. However, they significantly improved the corrosion

  5. 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.

  6. Sensitivity of polycrystal [local] plasticity to slip system kinematic hardening laws for Al 7075-T6

    DOE PAGES

    Hennessey, Conor; Castelluccio, Gustavo M.; McDowell, David L.

    2017-01-22

    The prediction of formation and early growth of microstructurally small fatigue cracks requires use of constitutive models that accurately estimate local states of stress, strain, and cyclic plastic strain. However, few research efforts have attempted to systematically consider the sensitivity of overall cyclic stress-strain hysteresis and higher order mean stress relaxation and plastic strain ratcheting responses introduced by the slip system back-stress formulation in crystal plasticity, even for face centered cubic (FCC) crystal systems. This paper explores the performance of two slip system level kinematic hardening models using a finite element crystal plasticity implementation as a User Material Subroutine (UMAT)more » within ABAQUS, with fully implicit numerical integration. The two kinematic hardening formulations aim to reproduce the cyclic deformation of polycrystalline Al 7075-T6 in terms of both macroscopic cyclic stress-strain hysteresis loop shape, as well as ratcheting and mean stress relaxation under strain- or stress-controlled loading with mean strain or stress, respectively. The first formulation is an Armstrong-Frederick type hardening-dynamic recovery law for evolution of the back stress. This approach is capable of reproducing observed deformation under completely reversed uniaxial loading conditions, but overpredicts the rate of cyclic ratcheting and associated mean stress relaxation. The second formulation corresponds to a multiple back stress Ohno-Wang type hardening law with nonlinear dynamic recovery. The adoption of this back stress evolution law greatly improves the capability to model experimental results for polycrystalline specimens subjected to cycling with mean stress or strain. As a result, the relation of such nonlinear dynamic recovery effects are related to slip system interactions with dislocation substructures.« less

  7. Sensitivity of polycrystal plasticity to slip system kinematic hardening laws for Al 7075-T6

    DOE PAGES

    Hennessey, Conor; Castelluccio, Gustavo M.; McDowell, David L.

    2017-02-01

    The prediction of formation and early growth of microstructurally small fatigue cracks requires use of constitutive models that accurately estimate local states of stress, strain, and cyclic plastic strain. However, few research efforts have attempted to systematically consider the sensitivity of overall cyclic stress-strain hysteresis and higher order mean stress relaxation and plastic strain ratcheting responses introduced by the slip system back-stress formulation in crystal plasticity, even for face centered cubic (FCC) crystal systems. This paper explores the performance of two slip system level kinematic hardening models using a finite element crystal plasticity implementation as a User Material Subroutine (UMAT)more » within ABAQUS, with fully implicit numerical integration. The two kinematic hardening formulations aim to reproduce the cyclic deformation of polycrystalline Al 7075-T6 in terms of both macroscopic cyclic stress-strain hysteresis loop shape, as well as ratcheting and mean stress relaxation under strain- or stress-controlled loading with mean strain or stress, respectively. The first formulation is an Armstrong-Frederick type hardening-dynamic recovery law for evolution of the back stress. This approach is capable of reproducing observed deformation under completely reversed uniaxial loading conditions, but overpredicts the rate of cyclic ratcheting and associated mean stress relaxation. The second formulation corresponds to a multiple back stress Ohno-Wang type hardening law with nonlinear dynamic recovery. The adoption of this back stress evolution law greatly improves the capability to model experimental results for polycrystalline specimens subjected to cycling with mean stress or strain. As a result, the relation of such nonlinear dynamic recovery effects are related to slip system interactions with dislocation substructures.« less

  8. Non-Chromate Aluminum Pretreatments, Phase 2

    DTIC Science & Technology

    2004-09-01

    September 2004 78 ALUMINUM AL2024-T3 ALUMINUM AL7075 -T6 PNL ID 4 Control 5...ALUMINUM - AL2024-T3 192 ALUMINUM - AL7075 -T6 112 Table 5.13: AMCOM – NAVAIR PANEL TEST MATRIX OCTOBER 2003 NCAP Phase II Interim Report

  9. Trivalent Chromium Solutions for Sealing Anodized Aluminum

    DTIC Science & Technology

    1994-12-20

    the comparatively innocuous trivalent form before acid , chromic acid , oxalic acid , sulfophthalic acid , boric disposal. This method is expensive and...or had only faint anodized aluminum substrates by immersion in a mildly traces of corrosion . All 7075-T6 panels provided with acid solution containing...alloy panels wereP 10 anodized in 15% (weight) sulfuric acid solution for 30 To produce improved corrosion resistance on anod- minutes at 21 C. at 18

  10. Corrosion protection comparison of a chromate conversion coating to a novel conductive polymer coating on aluminum alloys

    SciTech Connect

    Racicot, R.J.; Yang, S.C.; Brown, R.

    1997-12-01

    Comparisons of the corrosion resistance performance of a novel polyaniline based double strand conductive polymer coating versus a chromate conversion coating on two aluminum alloys were made. Potentiodynamic scans, electrochemical impedance spectroscopy (EIS) in 0.5N NaCl solutions and ASTM B-117 salt spray tests were performed on coated samples of AA7075-T6 and AA2024-T3 aluminum alloys. Results show the conductive polymer film offers, at the least, an equivalent protection performance as the chromate coating with a two order of magnitude reduction in corrosion current densities in cyclic polarization tests, near equivalent impedance values and less undercutting of a scribed area in salt spray test samples. In an acidic salt solution of pH 3.6, the conductive polymer offers an improved performance with a one order of magnitude higher impedance over the chromate coatings.

  11. Hybrid manufacturing processes for fusion welding and friction stir welding of aerospace grade aluminum alloys

    NASA Astrophysics Data System (ADS)

    Gegesky, Megan Alexandra

    Friction stir welding and processing can provide for joints in aerospace grade aluminum alloys that have preferable material properties as compared to fusion welding techniques. Aerospace grade aluminum alloys such as AA2024-T3 and AA7075-T6 are considered non-weldable by traditional fusion welding techniques. Improved mechanical properties over previously used techniques are usually preferable for aerospace applications. Therefore, by combining traditional fusion welding and friction stir processing techniques, it could be plausible to create more difficult geometries in manufactured parts instead of using traditional techniques. While this combination of fusion welding and friction stir processing is not a new technology, its introduction to aerospace grade aluminum alloys as well as non-weldable alloys, is new. This is brought about by a lowered required clamping force required by adding a fusion weld before a friction stir processing technique. The changes in properties associated with joining techniques include: microstructural changes, changes in hardness, tensile strength, and corrosion resistance. This thesis illustrates these changes for the non-weldable AA2024-T351 and AA7075-T651 as well as the weldable alloy AA5052-H32. The microhardness, tensile strength and corrosion resistance of the four processing states: base material, fusion welded material, friction stir welded material, and friction stir processed fusion welded material is studied. The plausibility of this hybrid process for the three different materials is characterized, as well as plausible applications for this joining technique.

  12. Low cost corrosion damage mitigation and improved fatigue performance of low plasticity burnished 7075-T6

    NASA Astrophysics Data System (ADS)

    Prevéy, Paul S.; Cammett, John

    2001-10-01

    Low plasticity burnishing (LPB) has been investigated as a surface enhancement process and corrosion mitigation method for aging aircraft structural applications. Compressive residual stresses reaching the alloy yield strength and extending to a depth of 1.25 mm (0.050 in.) deeper than typical corrosion damage is achievable. Excellent surface finish can be achieved with no detectable metallurgical damage to surface and subsurface material. Salt fog exposures of 100 and 500 h reduced the fatigue strength at 2×106 cycles by 50%. The LPB of the corroded surface, without removal of the corrosion product or pitted material, restored the 2×106 fatigue strength to greater than that of the original machined surface. The fatigue strength of the corroded material in the finite life regime (104 to 106 cycles) after LPB was 140 MPa (20 ksi) higher than the original uncorroded alloy and increased the life by an order of magnitude. Ease of adaptation to computer numerical control (CNC) machine tools allows LPB processing at costs and speeds comparable to machining operations. Low plasticity burnishing offers a promising new technology for mitigation of corrosion damage and improved fatigue life of aircraft structural components with significant cost and time savings over current practices.

  13. 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.

  14. The relative stress-corrosion-cracking susceptibility of candidate aluminum-lithium alloys for aerospace applications

    NASA Technical Reports Server (NTRS)

    Pizzo, P. P.

    1982-01-01

    Stress corrosion tests of Al-Li-Cu powder metallurgy alloys are described. Alloys investigated were Al-2.6% Li-1.4% and Al-2.6% Li-1.4% Cu-1.6% Mg. The base properties of the alloys were characterized. Process, heat treatment, and size/orientational effects on the tensile and fracture behavior were investigated. Metallurgical and electrochemical conditions are identified which provide reproducible and controlled parameters for stress corrosion evaluation. Preliminary stress corrosion test results are reported. Both Al-Li-Cu alloys appear more susceptible to stress corrosion crack initiation than 7075-T6 aluminum, with the magnesium bearing alloy being the most susceptible. Tests to determine the threshold stress intensity for the base and magnesium bearing alloys are underway. Twelve each, bolt loaded DCB type specimens are under test (120 days) and limited crack growth in these precracked specimens has been observed. General corrosion in the aqueous sodium chloride environment is thought to be obscuring results through crack tip blunting.

  15. Aluminum battery alloys

    DOEpatents

    Thompson, David S.; Scott, Darwin H.

    1985-01-01

    Aluminum alloys suitable for use as anode structures in electrochemical cs are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  16. Aluminum battery alloys

    DOEpatents

    Thompson, D.S.; Scott, D.H.

    1984-09-28

    Aluminum alloys suitable for use as anode structures in electrochemical cells are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  17. Evaluation of 7XXX-series aluminum alloys for the W87 aft support ring

    SciTech Connect

    Mahin, K.W.

    1985-03-01

    The study showed that the tensile properties of both 7075-T6 and 7050-T73651 decreased significantly after holding the alloys for any length of time at temperatures greater than 500/sup 0/F. After a 2-min hold at 575/sup 0/F, the yield strengths of 7075-T6 and 7050-T73651 were 217 MPa (31.5 ksi) and 245 MPa (35.6 ksi), respectively. There did not appear to be a significant difference in the mechanical properties between 7075-T6 and 7050-T6. Time at temperature appeared to be a critical parameter. Cycling the microstructure to 575/sup 0/F or above with no hold at temperature caused considerably less degradation in mechanical properties than a 2-min hold at temperature in all cases. Above 650/sup 0/F, both the ultimate tensile strength and the yield strength of the alloys reached a minimum of around 310 MPa (45 ksi) and 138 MPa (20 ksi), respectively. Evidence of a continuous grain boundary film of eta phase precipitates was found in the 7075-T6 alloy after a typical 575/sup 0/F thermal cycle. The presence of this grain boundary precipitate indicated a potential sensitivity of this alloy to stress corrosion cracking. Although the general environment for the aft support ring is controlled, the ring is expected to be under tension after assembly and exposure to small amounts of water vapor will probably occur. The conditions of stress, moisture, and susceptible microstructure increase the likelihood of stress corrosion cracking.

  18. Corrosion of aluminum and aluminum alloys

    SciTech Connect

    Davis, J.R.

    1999-01-01

    This new handbook presents comprehensive coverage of the corrosion behavior of aluminum and aluminum alloys, with emphasis on practical information about how to select and process these materials in order to prevent corrosion attack. Described are the characteristics of these materials and the influences of composition, mechanical working, heat treatment, joining methods, microstructure, and environmental variables on their corrosion.

  19. 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.

  20. A chrome-free conversion coating and sealant for aluminum and its alloys

    SciTech Connect

    Bibber, J.W.

    1999-07-01

    For over fifty years, chromates have been the standard against which other conversion coatings and/or sealants have been judged. Due to current environmental and safety concerns, they are being removed from use. This paper presents neutral salt-spray, filiform primer adhesion and electrical conductivity data on a commercial chromate-free, inorganic and non-toxic conversion coating used with a new and unique sealing emulsion. The seal is an organic water based emulsion which when dried on a permanganate based conversion coated aluminum surface will be polymerized, or cured, when heated to 250--300 F for 20 seconds or longer. The higher the temperature, or period of time, the greater the degree of polymerization. The polymerized film is as electrically conductive as chromate films and easily accepts and bonds to applied primers. For in-service repair a conventional heat-gun maybe used. For large surfaces, any other conventional heat source may be used. The 6061-T6, 7075-T6, and 2024-T3 series wrought alloys were tested and directly compared to current chromate based conversion coatings. The tests showed equivalent or superior results in all cases.

  1. Aluminum alloys with improved strength

    NASA Technical Reports Server (NTRS)

    Deiasi, R.; Adler, P.

    1975-01-01

    Mechanical strength and stress corrosion of new BAR and 7050 alloys that include Zn instead of Cr have been studied and compared with those of 7075 aluminum alloy. Added mechanical strength of new alloys is attributed to finer grain size of 5 to 8 micrometers, however, susceptibility to stress corrosion attack is increased.

  2. Crack Initiation and Growth Behavior at Corrosion Pit in 7075-T6 Under Biaxial and Uniaxial Fatigue

    DTIC Science & Technology

    2014-06-19

    general conical , hemispherical, and roughly saucer-shaped for steel and many alloys [41], as shown in Figure 2.2. Pits usually nucleate at chemical or...performed in a piezoelectric resonance system. Their results indicated that the presence of corrosion pits notably reduces the fatigue life of the

  3. Effects of Post-Weld Heat Treatment on the Mechanical Properties of Similar- and Dissimilar-Alloy Friction Stir Welded Blanks

    SciTech Connect

    Zadpoor, Amir Abbas; Sinke, Jos

    2011-01-17

    Friction stir welding is a solid state joining process with relatively low welding temperatures. Nevertheless, the mechanical properties of friction stir welded blanks are degraded after welding. Indeed, both strength and ductility of the welds are decreased after welding. Often, the resulting friction stir welded blanks need to be formed to their final structural shape. Therefore, the formability of friction stir welded blanks is of primary importance in the manufacturing of structural parts. This paper studies how the mechanical properties and particularly formability of friction stir welded blanks can be improved by applying a post weld heat treatment. Two aluminum alloys from 2000 and 7000 series, namely 2024-T3 and 7075-T6, are selected for the study. The sheet thickness of both materials is 2,0 mm. The selected alloys are welded in three configurations: 2024-T3 and 2024-T3, 7075-T6 and 7075-T6, and 2024-T3 and 7075-T6. The resulting welds are naturally aged for a few months. Three sets of standard dog bone shape tensile test specimens are then machined from the welds. The first set of the specimens is tested without any heat treatment. The second set of the specimens is solution heat treated and quenched before testing. The third set of the specimens is solution heat treated, quenched, and naturally aged for a week before testing. The mechanical properties of the three different sets of specimens are compared with each other. It is shown that careful selection of post weld heat-treatment can greatly improve the formability of friction stir welded blanks.

  4. 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)

  5. Aluminum and its light alloys

    NASA Technical Reports Server (NTRS)

    Merica, Paul D

    1920-01-01

    Report is a summary of research work which has been done here and abroad on the constitution and mechanical properties of the various alloy systems with aluminum. The mechanical properties and compositions of commercial light alloys for casting, forging, or rolling, obtainable in this country are described.

  6. [Microbiological corrosion of aluminum alloys].

    PubMed

    Smirnov, V F; Belov, D V; Sokolova, T N; Kuzina, O V; Kartashov, V R

    2008-01-01

    Biological corrosion of ADO quality aluminum and aluminum-based construction materials (alloys V65, D16, and D16T) was studied. Thirteen microscopic fungus species and six bacterial species proved to be able to attack aluminum and its alloys. It was found that biocorrosion of metals by microscopic fungi and bacteria was mediated by certain exometabolites. Experiments on biocorrosion of the materials by the microscopic fungus Alternaria alternata, the most active biodegrader, demonstrated that the micromycete attack started with the appearance of exudate with pH 8-9 on end faces of the samples.

  7. 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.

  8. Modeling dissolution in aluminum alloys

    NASA Astrophysics Data System (ADS)

    Durbin, Tracie Lee

    2005-07-01

    Aluminum and its alloys are used in many aspects of modern life, from soda cans and household foil to the automobiles and aircraft in which we travel. Aluminum alloy systems are characterized by good workability that enables these alloys to be economically rolled, extruded, or forged into useful shapes. Mechanical properties such as strength are altered significantly with cold working, annealing, precipitation-hardening, and/or heat-treatments. Heat-treatable aluminum alloys contain one or more soluble constituents such as copper, lithium, magnesium, silicon and zinc that individually, or with other elements, can form phases that strengthen the alloy. Microstructure development is highly dependent on all of the processing steps the alloy experiences. Ultimately, the macroscopic properties of the alloy depend strongly on the microstructure. Therefore, a quantitative understanding of the microstructural changes that occur during thermal and mechanical processing is fundamental to predicting alloy properties. In particular, the microstructure becomes more homogeneous and secondary phases are dissolved during thermal treatments. Robust physical models for the kinetics of particle dissolution are necessary to predict the most efficient thermal treatment. A general dissolution model for multi-component alloys has been developed using the front-tracking method to study the dissolution of precipitates in an aluminum alloy matrix. This technique is applicable to any alloy system, provided thermodynamic and diffusion data are available. Treatment of the precipitate interface is explored using two techniques: the immersed-boundary method and a new technique, termed here the "sharp-interface" method. The sharp-interface technique is based on a variation of the ghost fluid method and eliminates the need for corrective source terms in the characteristic equations. In addition, the sharp-interface method is shown to predict the dissolution behavior of precipitates in aluminum

  9. Substitute conversion coatings on aluminum for waste minimization

    SciTech Connect

    Buchheit, R.G.; Bode, M.D.; Stoner, G.E.

    1991-09-01

    Chromate conversion coatings such as Parker Company`s Alodine coatings are widely used to increase the corrosion resistance of aluminum and aluminum alloys. The primary disadvantage of chromate-based processes is that they use and produce as waste hexavalent chromium (Cr{sup 6+}). We have discovered that the corrosion resistance of Al can be increased by forming an inorganic barrier coating using chemicals that pose a relatively small environmental hazard. These new coatings are formed using a process that is procedurally identical to the basic chromate conversion process. We have prepared new and conventional coatings on 1100 (99.0 Al minimum), 2024-T3 (Al-Cu-Mg) and 7075-T6 (Al-Zn-Mg) commercial sheet stock for accelerated electrochemical testing and coating conductivity testing. Results show that the new coatings offer increased corrosion resistance compared to uncoated Al, but do not yet match the performance of the chromate conversion coatings. The conductivity of these new films on 1100 Al is comparable to that of Alodine coatings; however, the new coatings are more resistive than Alodine coatings on 2024-T3 and 7075-T6.

  10. Supersaturated Aluminum Alloy Powders.

    DTIC Science & Technology

    1981-07-15

    shown in Fig. 18 . It .an be clearly seen that most of the iron is concentrated in the precipitates (Fig. 18 ), X-ray mapping immage for the chromium...At 232°C our alloys are comparable to 2� and 2618 in their tensile properties, and except for alloy #1 which at t i temperature has elongation of...demonstrate better yield strength and UTS than the 2219, 2618 and are comparable to the ALCOA alloy. They show however higher ductility than the ALCOA alloy

  11. Thermomechanical Processing of Al Alloy 2090 for Grain Refinement and Superplasticity.

    DTIC Science & Technology

    1987-12-01

    introduced as a replacement for the 7075 -T6 alloy. The ouroose of this research is to investigate the applicability of thermmechanical processing...effect of the processing on microstructural evolution and the super- cla~tic behavior of this material. ~ - 20 DiSTRiBLTrON ’AVAILABILITY OF ABSTRAC’ 2...percent lower density and 10 percent ".>iqher elastic modulus, has been introduced as a ronlacment for the 7075 -T6 alloy. The purpose of this research is

  12. Aluminum Alloys--Industrial Deformable, Sintered and Light Aluminum Alloys

    DTIC Science & Technology

    1974-10-30

    thin film on the particles of the highly dispersed aluminum powder when it is ground in spherical mills in a nitrogen atmosphere in which the...principal elements, certain small admixtures are introduced into the alloys, which have a considerable effect on the decay kinetics of the oversaturated...strengthened by the insoluble dispersed alumina particles. Fine grinding of the original powder provides the dispersion of the oxide films and particles

  13. Nd:YAG laser welding aluminum alloys

    SciTech Connect

    Jimenez, E. Jr.

    1992-02-01

    Autogenous Nd:YAG laser welding wrought 4047, 1100, 3003, 2219, 5052, 5086, 5456, and 6061 and cast A356 aluminum alloys to cast A356 aluminum alloy in restrained annular weld joints was investigated. The welds were 12.7 mm (0.375 in.) and 9.5 mm (0.375 in.) diameter with approximately 0.30 mm (0.012 in.) penetration. This investigation determined 4047 aluminum alloy to be the optimum alloy for autogenous Nd:YAG laser welding to cast A356 aluminum alloy. This report describes the investigation and its results.

  14. Superplasticity in aluminum alloys

    SciTech Connect

    Nieh, T. G.

    1997-12-01

    We have characterized in the Al-Mg system the microstructure and mechanical properties of a cold-rolled Al-6Mg-0.3Sc alloy. The alloy exhibited superplasticity at relatively high strain rates (about 10-2 s-1). At a strain rate of 10-2 s-1 there exists a wide temperature range (475-520`C) within which the tensile elongation is over 1000%. There also exists a wide strain rate range (10-3 - 10-1 s-1) within which the tensile elongation is over 500%. The presence of Sc in the alloy results in a uniform distribution of fine coherent Al3SC precipitates which effectively pin grain and subgrain boundaries during static and continuous recrystallization. As a result, the alloy retains its fine grain size (about 7 micron), even after extensive superplastic deformation (>1000%). During deformation, dislocations Mg with a high Schmidt factor slip across subgrains but are trapped by subgrain boundaries, as a result of the strong pining of Al3Sc. This process leads to the conversion of low-angled subgrain boundaries to high-angled grain boundaries and the subsequent grain boundary sliding, which produces superelasticity. A model is proposed to describe grain boundary sliding accommodated by dislocation glide across grains with a uniform distribution of coherent precipitates. The model predictions is consistent with experimental observations.

  15. PREPARATION OF ACTINIDE-ALUMINUM ALLOYS

    DOEpatents

    Moore, R.H.

    1962-09-01

    BS>A process is given for preparing alloys of aluminum with plutonium, uranium, and/or thorium by chlorinating actinide oxide dissolved in molten alkali metal chloride with hydrochloric acid, chlorine, and/or phosgene, adding aluminum metal, and passing air and/or water vapor through the mass. Actinide metal is formed and alloyed with the aluminum. After cooling to solidification, the alloy is separated from the salt. (AEC)

  16. A correlation between salt spray and electrochemical impedance spectroscopy test results for conversion-coated aluminum alloys

    SciTech Connect

    Buchheit, R.G.; Cunningham, M.; Jensen, H.; Kendig, M.W.; Martinez, M.A.

    1998-01-01

    The corrosion resistance of 33 inorganic conversion coatings applied to five aluminum alloys was tested by salt spray exposure and electrochemical impedance spectroscopy (EIS). Results were evaluated to determine if a relationship existed. Individual salt spray test panels, with an area of 30 in.{sup 2} (194 cm{sup 2}), were inspected visually at regular intervals up to 168 h of exposure. At each inspection interval, panels were assigned a pass rank if <5 pits were observed, or a fail rank if >5 pits were observed. EIS data were analyzed using a simple equivalent circuit which yielded a coating resistance (R{sub c}), which was used as a figure of merit to assess coating performance. Examination of the data showed both tests could be sensitive discriminators of corrosion protection, but that EIS was more discriminating in the extremes of coating performance. Analysis showed the probability of achieving a passing salt spray result increased as R{sub c} increased. In the regimes where both tests were sensitive, regression analysis showed a linear relationship existed for each alloy substrate between the log of R{sub c} and the probability of a coating meeting the pass/fail criterion in salt spray. Based upon these relationships, threshold R{sub c} values were proposed to define the minimum value for which a given coating can be expected to attain a passing result in a 168-h salt spray test. These values were 2 {times} 10{sup 6} {Omega}-cm{sup 2} to 5 {times} 10{sup 6} {Omega}-cm{sup 2} for Al 356 (UNS A13560), Al 2024-T3 (UNS A92024), and Al 6061-T6 (UNS A96061); 1.5 {times} 10{sup 7} for Al 7075-T6 (UNS A97075); and 2.3 {times} 10{sup 6} {Omega}-cm{sup 2} for Al 3003 (UNS A93003).

  17. 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.

  18. Low-aluminum content iron-aluminum alloys

    SciTech Connect

    Sikka, V.K.; Goodwin, G.M.; Alexander, D.J.

    1995-06-01

    The low-aluminum-content iron-aluminum program deals with the development of a Fe-Al alloy with aluminum content such as a produce the minimum environmental effect at room temperature. The FAPY is an Fe-16 at. % Al-based alloy developed at the Oak Ridge National Laboratory as the highest aluminum-containing alloy with essentially no environmental effect. The chemical composition for FAPY in weight percent is: aluminum = 8.46, chromium = 5.50, zirconium = 0.20, carbon = 0.03, molybdenum = 2.00, yttrium = 0.10 and iron = 83.71. The ignots of the alloy can be hot worked by extrusion, forging, and rolling processes. The hot-worked cast structure can be cold worked with intermediate anneals at 800{degrees}C. Typical room-temperature ductility of the fine-grained wrought structure is 20 to 25% for this alloy. In contrast to the wrought structure, the cast ductility at room temperature is approximately 1% with a transition temperature of approximately 100 to 150{degrees}C, above which ductility values exceed 20%. The alloy has been melted and processed into bar, sheet, and foil. The alloy has also been cast into slabs, step-blocks of varying thicknesses, and shapes. The purpose of this section is to describe the welding response of cast slabs of three different thicknesses of FAPY alloy. Tensile, creep, and Charpy-impact data of the welded plates are also presented.

  19. 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.

  20. Surface alloying of silicon into aluminum substrate.

    SciTech Connect

    Xu, Z.

    1998-10-28

    Aluminum alloys that are easily castable tend to have lower silicon content and hence lower wear resistance. The use of laser surface alloying to improve the surface wear resistance of 319 and 320 aluminum alloys was examined. A silicon layer was painted onto the surface to be treated. A high power pulsed Nd:YAG laser with fiberoptic beam delivery was used to carry out the laser surface treatment to enhance the silicon content. Process parameters were varied to minimize the surface roughness from overlap of the laser beam treatment. The surface-alloyed layer was characterized and the silicon content was determined.

  1. Solution Potentials Indicate Aluminum-Alloy Tempers

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1985-01-01

    Report discusses use of solution potential as measure of temper of aluminum alloys. Technique based on fact that different tempers or heat treatments exhibit different solution potentials as function of aging time.

  2. Boric/sulfuric acid anodizing of aluminum alloys 2024 and 7075: Film growth and corrosion resistance

    SciTech Connect

    Thompson, G.E.; Zhang, L.; Smith, C.J.E.; Skeldon, P.

    1999-11-01

    The influence of boric acid (H{sub 3}BO{sub 3}) additions to sulfuric acid (H{sub 2}SO{sub 4}) were examined for the anodizing of Al 2024-T3 (UNS A92024) and Al 7075-T6 (UNS A97075) alloys at constant voltage. Alloys were pretreated by electropolishing, by sodium dichromate (Na{sub 2}Cr{sub 2}O{sub 7})/H{sub 2}SO{sub 4} (CSA) etching, or by alkaline etching. Current-time responses revealed insignificant dependence on the concentration of H{sub 3}BO{sub 3} to 50 g/L. Pretreatments affected the initial film development prior to the establishment of the steady-state morphology of the porous film, which was related to the different compositions and morphologies of pretreated surfaces. More detailed studies of the Al 7075-T6 alloy indicated negligible effects of H{sub 3}BO{sub 3} on the coating weight, morphology of the anodic film, and thickening rate of the film, or corrosion resistance provided by the film. In salt spray tests, unsealed films formed in H{sub 2}SO{sub 4} or mixed acid yielded similar poor corrosion resistances, which were inferior to that provided by anodizing in chromic acid (H{sub 2}CrO{sub 4}). Sealing of films in deionized water, or preferably in chromate solution, improved corrosion resistance, although not matching the far superior performance provided by H{sub 2}CrO{sub 4} anodizing and sealing.

  3. Casting Characteristics of Aluminum Die Casting Alloys

    SciTech Connect

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The research program investigates the casting characteristics of selected aluminum die casting alloys. Specifically, the alloys' tendencies towards die soldering and sludge formation, and the alloys' fluidity and machinability are evaluated. It was found that: When the Fe and Mn contents of the alloy are low; caution has to be taken against possible die soldering. When the alloy has a high sludge factor, particularly a high level of Fe, measures must be taken to prevent the formation of large hardspots. For this kind of alloy, the Fe content should be kept at its lowest allowable level and the Mn content should be at its highest possible level. If there are problems in die filling, measures other than changing the alloy chemistry need to be considered first. In terms of alloy chemistry, the elements that form high temperature compounds must be kept at their lowest allowable levels. The alloys should not have machining problems when appropriate machining techniques and machining parameters are used.

  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 handbook: Aluminum alloy 2219

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

    A summary of the materials property information for aluminum 2219 alloy is presented. The scope of the information includes physical and mechanical properties at cryogenic, ambient, and elevated temperatures. Information on material procurement, metallurgy of the alloy, corrosion, environmental effects, fabrication, and joining techniques is developed.

  6. Precipitation hardening in aluminum alloy 6022

    SciTech Connect

    Miao, W.F.; Laughlin, D.E.

    1999-03-05

    Although the precipitation process in Al-Mg-Si alloys has been extensively studied, the understanding of the hardening process is still incomplete, since any change in composition, processing and aging practices, etc., could affect the precipitation hardening behavior. In this paper, hardness measurements, differential scanning calorimetry and transmission electron microscopy have been utilized to study the precipitation hardening behavior in aluminum alloy 6022.

  7. Major and Minor Constituents of Aluminum Alloys

    DTIC Science & Technology

    1986-03-01

    sample alloys obtained by both techniques. Keywords: Atomic Absorption Spectroscopy (AAS), Inductively Coupled Plasma Atomic Emission Spectroscopy(ICP-AES).... absorption spectroscopy and inductively coupled plasma atomic emission spectroscopy are used for the determination of major magnesium, lithium, copper, zinc...An accurate analysis of aluminum alloys is required for quality control and characterization purposes. The two analytical techniques atomic

  8. 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.

  9. Processing of 2090 Aluminum Alloy for Superplasticity

    DTIC Science & Technology

    1988-06-01

    behavior has now been extensively documented in Al-Mg alloys, with elongations in excess of 1,000 percent obtained in many cases in these alloys. The...crucial. Characteristics of superplastic behavior include a fine grain size (two to five microns), a strain rate sensitivity coefficient m > 0.3, 1 I| and...seven to eight percent less and demonstrates ten percent higher stiffness than 7075 aluminum, an alloy it was designed to replace. This is due to the

  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. Application of Rapidly Solidified Alloys.

    DTIC Science & Technology

    1978-10-01

    11 4 Microstructure of Conventionally Processed Al 7075-T6 ............................... 12 5 XSR 30-1 Extruded and Swaged ...14 6 Microstructure of XSR-33 Extruded and Swaged ........................................ 15 LIST...6 7 Swaging Schedule for XSR 30-1 .................................................................. 7 8 Hardness of Aluminum Extrusions, R

  12. Environmental fatigue in aluminum-lithium alloys

    NASA Technical Reports Server (NTRS)

    Piascik, Robert S.

    1992-01-01

    Aluminum-lithium alloys exhibit similar environmental fatigue crack growth characteristics compared to conventional 2000 series alloys and are more resistant to environmental fatigue compared to 7000 series alloys. The superior fatigue crack growth behavior of Al-Li alloys 2090, 2091, 8090, and 8091 is due to crack closure caused by tortuous crack path morphology and crack surface corrosion products. At high R and reduced closure, chemical environment effects are pronounced resulting in accelerated near threshold da/dN. The beneficial effects of crack closure are minimized for small cracks resulting in rapid growth rates. Limited data suggest that the 'chemically small crack' effect, observed in other alloy system, is not pronounced in Al-Li alloys. Modeling of environmental fatigue in Al-Li-Cu alloys related accelerated fatigue crack growth in moist air and salt water to hydrogen embrittlement.

  13. 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.

  14. 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.

  15. Welding of Aluminum Alloys to Steels: An Overview

    DTIC Science & Technology

    2013-08-01

    95] K. Kimapong1, T. Watanabe, Effect of welding process parameters on mechanical property of FSW lap joint between aluminum alloy and steel ...UNCLASSIFIED: Distribution Statement A. Approved for public release. 1 UNCLASSIFIED Welding of aluminum alloys to steels : an overview M. Mazar...welding methods for joining aluminum alloys to steels . The microstructural development, mechanical properties and application of the joints are discussed

  16. Mechanical Properties of Aluminum-alloy Rivets

    NASA Technical Reports Server (NTRS)

    Brueggeman, Wm C

    1936-01-01

    The development of metal construction for aircraft has created a need for accurate and detailed information regarding the strength of riveted joints in aluminum-alloy structures. To obtain this information the National Bureau of Standards in cooperation with the National Advisory Committee for Aeronautics is investigating the strength of riveted joints in aluminum alloys. The strength of riveted joints may be influenced by the form of the head, the ratio of the rivet diameter to the sheet thickness, the driving stress, and other factors. This note gives the results of tests to develop the riveting technique for test specimens and to determine the effects of these factors.

  17. Anisotropic Effects on Constitutive Model Parameters of Aluminum Alloys

    DTIC Science & Technology

    2012-01-01

    strength 7075-T651aluminum alloy . Johnson - Cook model constants determined for Al7075-T651 alloy bar material failed to simulate correctly the penetration...structural components made of high strength 7075-T651aluminum alloy . Johnson - Cook model constants determined for Al7075-T651 alloy bar material...rate sensitivity, Johnson - Cook , constitutive model. PACS: 62.20 .Dc, 62.20..Fe, S 62.50. +p, 83.60.La INTRODUCTION Aluminum 7075 alloys are

  18. 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.

  19. Welding the four most popular aluminum alloys

    SciTech Connect

    Irving, B.

    1994-02-01

    The fact that business is good in aluminum welding is a sure sign that more manufacturers and fabricators are using GMA and GTA welding to build new products out of this lightweight nonferrous metal. Among the most widely specified weldable grades are Alloys 6061, 5083, 5052 and 5454. A rundown on these four alloys, including properties and selected applications, is provided. Any company working with aluminum for the first time needs to know something about these four alloys. Alloys of copper-magnesium-silicon combination, of which 6061 is one, are heat-treatable. The three 5XXX series alloys, on the other hand, are nonheat-treatable. According to P.B. Dickerson, consultant, Lower Burrell, Pa., 5083, because of its high magnesium content, is the easiest of the four alloys to arc weld. Dickerson put the cut-off point in weldability at 3.5% magnesium. To prevent cracking, he added, both 6061 and 5052 require much more filler metal than do the other two alloys. Alloy 6061 consists of 0.25Cu, 0.6Si, 1.0Mg, and 0.20Cr. The main applications for 6061 aluminum are structural, architectural, automotive, railway, marine and pipe. It has good formability, weldability, corrosion resistance and strength. Although the 6XXX series alloys are prone to hot cracking, this condition can be readily overcome by correct choice of joint design and electrode. The most popular temper for 6061 is T6, although the -T651, -T4, and -F temper are also popular. The -T651 temper is like a -T6 temper, only it has received some final stretch hardening. The -T4 temper has been solution heat-treated and quenched. The -F temper is in the as-fabricated condition.

  20. 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.

  1. 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.

  2. Metallography of Aluminum and Its Alloys : Use of Electrolytic Polishing

    NASA Technical Reports Server (NTRS)

    Jacquet, Pierre A

    1955-01-01

    Recent methods are described for electropolishing aluminum and aluminum alloys. Numerous references are included of electrolytic micrographic investigations carried out during the period 1948 to 1952. A detailed description of a commercial electrolytic polishing unit, suitable for micrographic examination of aluminum and its alloys, is included.

  3. Galvanic Corrosion of Al-7075-T6 and Steel-4340 Coupled to Brass QQ-B- 626,360 and Al-7075-T6 Coupled to Steel-4130 and Steel-4340: Exposure to Aqueous NaCl and Salt-Fog Environments

    DTIC Science & Technology

    1986-06-30

    between the copper plates fail. Reboul (3) and Mansfeld et al. (4) provide excellent reviews on the galvanic corrosion behavior of aluminum coupled to...A.S.T.M., STP 576, 1976), p. 20. 2. Baboian, R,, ibid., p. 5. 3. Reboul , M. C., Corrosion, Vol. 35, No. 9, 1979, p. 423, 4. Nansfeld, F., lIcngstenbcrg

  4. The Delayed Fracture of Aluminum Alloys.

    DTIC Science & Technology

    1981-01-01

    if necessary and Identify by block number) aluminum alloys, stress - corrosion cracking, oxide film, Auger electron spectroscopy, Auger depth profiling...revere Ide If r ecester’ nd Ientify by block number). b -. ,h 0 unJaInenta mechanZsm of stress - corrosion cracking (SCC) has been studied for high-purity...these specimens is not intergranular. Fracture appears to have originated through pitting corrosion , which caused local stress concentration leading to

  5. Thermal coatings for titanium-aluminum alloys

    NASA Technical Reports Server (NTRS)

    Cunnington, George R.; Clark, Ronald K.; Robinson, John C.

    1993-01-01

    Titanium aluminides and titanium alloys are candidate materials for use in hot structure and heat-shield components of hypersonic vehicles because of their good strength-to-weight characteristics at elevated temperature. However, in order to utilize their maximum temperature capability, they must be coated to resist oxidation and to have a high total remittance. Also, surface catalysis for recombination of dissociated species in the aerodynamic boundary layer must be minimized. Very thin chemical vapor deposition (CVD) coatings are attractive candidates for this application because of durability and very light weight. To demonstrate this concept, coatings of boron-silicon and aluminum-boron-silicon compositions were applied to the titanium-aluminides alpha2 (Ti-14Al-21Nb), super-alpha2 (Ti-14Al-23-Nb-2V), and gamma (Ti-33Al-6Nb-1Ta) and to the titanium alloy beta-21S (Ti-15Mo-3Al-3Nb-0.2Si). Coated specimens of each alloy were subjected to a set of simulated hypersonic vehicle environmental tests to determine their properties of oxidation resistance, surface catalysis, radiative emittance, and thermal shock resistance. Surface catalysis results should be viewed as relative performance only of the several coating-alloy combinations tested under the specific environmental conditions of the LaRC Hypersonic Materials Environmental Test System (HYMETS) arc-plasma-heated hypersonic wind tunnel. Tests were also conducted to evaluate the hydrogen transport properties of the coatings and any effects of the coating processing itself on fatigue life of the base alloys. Results are presented for three types of coatings, which are as follows: (1) a single layer boron silicon coating, (2) a single layer aluminum-boron-silicon coating, and (3) a multilayer coating consisting of an aluminum-boron-silicon sublayer with a boron-silicon outer layer.

  6. Superplasticity in Thermomechanically Processed High Magnesium Aluminum-Magnesium Alloys.

    DTIC Science & Technology

    1984-03-01

    California DTIC EECTE JL I 1984 THESIS SUPERPLASTICITY IN THERMOMECHANICALLY PROCESSED HIGH MAGNESIUM ALUMINUM-MAGNESIUM ALLOYS C:L by CD) John J. Becker...High Magnesium Aluminum- March 1984 Magnesium Alloys S. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(@) S. CONTRACT OR GRANT NUMBER(&) John J. Becker 9...magnesium, aluminum-magnesium alloys were investigated. The thermomechanical processing itself included warm rolling at 300°C to 94% reduction

  7. Mechanical properties of laser welded aluminum alloys

    SciTech Connect

    Douglass, D.M.; Mazumder, J.

    1996-12-31

    The demand for lighter weight vehicles has prompted accelerated development in processing aluminum alloys for automobile structural applications. One of the current research initiatives centers on laser beam welding of aluminum alloys. Autogenous butt welds have been performed on Al 3003, 5754, 6111, and 6061-T6 plates with a 6 kW CO2 laser. For 6061, tensile data indicate about 60% of the base metal strength was attained in the as-welded condition, with a brittle fracture occurring through the weld. A post-weld heat treatment to the T6 condition resulted in a recovery of original ultimate tensile strengths, although these also failed in the weld. Hardness measurements of the post-weld T6 reveal a uniform hardness across the HAZ and fusion zone that is comparable to the original hardness. All 3003 welds fractured in the parent material in a ductile fashion. A high quality bead was consistently achieved with the 3003 alloy, whereas the other alloys demonstrated bead irregularities. SEM photographs reveal large, spherical pores, suggesting that they were formed by gas entrapment rather than by shrinkage.

  8. 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

  9. Bismuth alloy potting seals aluminum connector in cryogenic application

    NASA Technical Reports Server (NTRS)

    Flower, J. F.; Stafford, R. L.

    1966-01-01

    Bismuth alloy potting seals feedthrough electrical connector for instrumentation within a pressurized vessel filled with cryogenic liquids. The seal combines the transformation of high-bismuth content alloys with the thermal contraction of an external aluminum tube.

  10. Dry machinability of aluminum alloys.

    SciTech Connect

    Shareef, I.; Natarajan, M.; Ajayi, O. O.; Energy Technology; Department of IMET

    2005-01-01

    Adverse effects of the use of cutting fluids and environmental concerns with regard to cutting fluid disposability is compelling industry to adopt Dry or near Dry Machining, with the aim of eliminating or significantly reducing the use of metal working fluids. Pending EPA regulations on metal cutting, dry machining is becoming a hot topic of research and investigation both in industry and federal research labs. Although the need for dry machining may be apparent, most of the manufacturers still consider dry machining to be impractical and even if possible, very expensive. This perception is mainly due to lack of appropriate cutting tools that can withstand intense heat and Built-up-Edge (BUE) formation during dry machining. The challenge of heat dissipation without coolant requires a completely different approach to tooling. Special tooling utilizing high-performance multi-layer, multi-component, heat resisting, low friction coatings could be a plausible answer to the challenge of dry machining. In pursuit of this goal Argonne National Labs has introduced Nano-crystalline near frictionless carbon (NFC) diamond like coatings (DLC), while industrial efforts have led to the introduction of composite coatings such as titanium aluminum nitride (TiAlN), tungsten carbide/carbon (WC/C) and others. Although, these coatings are considered to be very promising, they have not been tested either from tribological or from dry machining applications point of view. As such a research program in partnership with federal labs and industrial sponsors has started with the goal of exploring the feasibility of dry machining using the newly developed coatings such as Near Frictionless Carbon Coatings (NFC), Titanium Aluminum Nitride (TiAlN), and multi-layer multicomponent nano coatings such as TiAlCrYN and TiAlN/YN. Although various coatings are under investigation as part of the overall dry machinability program, this extended abstract deals with a systematic investigation of dry

  11. Microstructures and properties of aluminum die casting alloys

    SciTech Connect

    M. M. Makhlouf; D. Apelian; L. Wang

    1998-10-01

    This document provides descriptions of the microstructure of different aluminum die casting alloys and to relate the various microstructures to the alloy chemistry. It relates the microstructures of the alloys to their main engineering properties such as ultimate tensile strength, yield strength, elongation, fatigue life, impact resistance, wear resistance, hardness, thermal conductivity and electrical conductivity. Finally, it serves as a reference source for aluminum die casting alloys.

  12. 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.

  13. 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.

  14. 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%.

  15. 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.

  16. 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.

  17. The Elastic Constants for Wrought Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Templin, R L; Hartmann, E C

    1945-01-01

    There are several constants which have been devised as numerical representations of the behavior of metals under the action of loadings which stress the metal within the range of elastic action. Some of these constants, such as Young's modulus of elasticity in tension and compression, shearing modulus of elasticity, and Poisson's ratio, are regularly used in engineering calculations. Precise tests and experience indicate that these elastic constants are practically unaffected by many of the factors which influence the other mechanical properties of materials and that a few careful determinations under properly controlled conditions are more useful and reliable than many determinations made under less favorable conditions. It is the purpose of this paper to outline the methods employed by the Aluminum Research Laboratories for the determination of some of these elastic constants, to list the values that have been determined for some of the wrought aluminum alloys, and to indicate the variations in the values that may be expected for some of the commercial products of these alloys.

  18. 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.

  19. 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.

  20. Benign joining of ultrafine grained aerospace aluminum alloys using nanotechnology.

    PubMed

    Longtin, Rémi; Hack, Erwin; Neuenschwander, Jürg; Janczak-Rusch, Jolanta

    2011-12-22

    Ultrafine grained aluminum alloys have restricted applicability due to their limited thermal stability. Metalized 7475 alloys can be soldered and brazed at room temperature using nanotechnology. Reactive foils are used to release heat for milliseconds directly at the interface between two components leading to a metallurgical joint without significantly heating the bulk alloy, thus preserving its mechanical properties.

  1. Investigation of the structure/property relationship of spray-formed 7XXX series high-strength aluminum alloys and their metal matrix composites

    NASA Astrophysics Data System (ADS)

    Sharma-Judd, Malavika M.

    2000-12-01

    , alloys with zinc contents over 12 wt. % attained the highest concentration of structural particles. One alloy displayed high strengths exceeding all others in the study. The superior strength properties were attributed to the addition of scandium, which produced a fine dispersion of the Al3Sc phase. This finely dispersed phase created additional strengthening through, coherency mismatch of Al3Sc and Al3(Sc,Zr) precipitates with the matrix, and ordered particle strengthening. The spray formed extrusions exhibited a loss in fracture resistance (K Q), compared to IM 7075 alloys. Characterization of the fracture surfaces indicated a predominantly intergranular decohesion, possibly facilitated by the presence of incoherent particles at the grain boundary regions and by the large strength differential between the matrix and precipitate zone. The MMC materials displayed a large increase in fatigue strength compared to commercial IM 7075-T6 and -T7 alloys. The enhanced fatigue performance of the spray formed alloys is attributed to low crack growth rates, which are a consequence of inhomogeneous slip. It is believed that the massive presence of coherent and semicoherent (GP zones and eta' phase) particles of reduced dimension in the spray formed alloys allowed a highly inhomogeneous slip behavior, where a slip reverse mechanism was operative.

  2. Fabrication of Porous Aluminum Using Gases Intrinsically Contained in Aluminum Alloy Die Castings

    NASA Astrophysics Data System (ADS)

    Hangai, Yoshihiko; Utsunomiya, Takao

    2009-06-01

    Closed-cell porous aluminum was fabricated using gases intrinsically contained in aluminum alloy die castings without using a blowing agent. By incorporating the friction stir processing technique, porous aluminum with a porosity of more than 50 pct was successfully obtained at a holding temperature of 923 to 948 K and a holding time of 10 minutes. This proposed die-casting route has high potential for fabricating porous aluminum at a low cost by a higher productivity process.

  3. 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.

  4. 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.

  5. Thermotransport in liquid aluminum-copper alloys

    NASA Technical Reports Server (NTRS)

    Bhat, B. N.

    1973-01-01

    A thermotransport study was made on a series of liquid aluminum-copper alloys which contained from trace amounts to 33 weight percent copper. The samples in the form of narrow capillaries were held in known temperature gradient of thermotransport apparatus until the stationary state was reached. The samples were analyzed for the concentration of copper along the length. Copper was observed to migrate to the colder regions in all the samples. The heat of transport, Q*, was determined for each composition from a plot of concentration of copper versus reciprocal absolute temperature. The value of Q* is the highest at trace amounts of copper (4850 cal/gm-atom), but decreases with increasing concentration of copper and levels off to 2550 cal/gm-atom at about 25 weight percent copper. The results are explained on the basis of electron-solute interaction and a gas model of diffusion.

  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. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Friction Stir Welding of Aluminum and Titanium Alloys

    DTIC Science & Technology

    2007-11-02

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

  13. 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.

  14. Corrosion protection of high-copper aluminum alloys using green technology

    SciTech Connect

    Mansfeld, F.; Wang, Y.

    1995-09-01

    The concept of surface modification as a new method of corrosion protection using chemicals without toxic problems is described for the Al alloys Al 6061, Al 7075-T6 and Al 2024-T3. In the Ce-Mo process Ce and Mo are incorporated into the original oxide film by chemical and electrochemical processes. The resulting surfaces are resistant to pitting in aggressive solutions such as 0.5 N NaCl. Surface modified Al 6013 has passed the salt spray test according to ASTM B 117. For Al 6061 and 7075, hot solutions of CeCl{sub 3} and Ce(NO{sub 3}){sub 3} are used, while for Al 2024 CeCl{sub 3} is replaced by Ce acetate. For all alloys anodic polarization is carried out in Na{sub 2}MoO{sub 4}. For Al 2024 and Al 7075 a Cu removal pre-treatment step is used in which Cu intermetallic compounds are removed from the outer surface layers. The resistance to localized corrosion has been evaluated by recording of impedance spectra in 0.5 N NaCl for 30 days. Surface analysis data suggest that Ce and Mo are concentrated at sites where local cathodes such as Cu intermetallic compounds are located. Polarization curves show that both the cathodic and the anodic reaction are inhibited on modified surfaces. The pitting potential E{sub pit} is increased for surface modified samples at constant corrosion potential E{sub corr}. This result could be due to a decrease of the amount of Cl adsorbed at a given potential for oxide layers containing Ce and Mo.

  15. 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.

  16. Aluminum alloy anode materials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Sun, Z. H.; Chen, Z. F.; Fu, Q. W.; Jiang, X. Y.

    2017-03-01

    Aluminum has larger theoretical capacity of 2235 mAh/g than that of graphite (372 mAh/g), but it has big disadvantages including shorter cycle life and higher irreversible capacity loss. Improving cycle performance can be obtained via alloying of aluminum. In this paper, two ternary aluminum alloy, Al7Cu2Fe and Al73Cu5Fe22 were prepared. The main phase of Al7Cu2Fe alloy was Al7Cu2Fe. The heat treatment increased the proportion of Al7Cu2Fe. The main phase of Al73Cu5Fe22 alloy was Al60Cu30Fe10. The heat treatment reduced the proportion of Al60Cu30Fe10. For two alloys, the heat treatment could increase discharge capacity compared with cast alloy. The discharge capacity was improved by 50%. The content of aluminum in alloys has little effect on improving cycle performance, and it has obvious influence on the phase structure of alloy with heat treatment.

  17. Improvements in springback control by external force laser-assisted sheet bending of titanium and aluminum alloys

    NASA Astrophysics Data System (ADS)

    Gisario, A.; Barletta, M.; Venettacci, S.

    2016-12-01

    The present investigation deals with an external-force laser assisted bending process of Grade 2 CP titanium and AA 7075 T6 aluminum sheets. High bending angles, sharp fillet radii and control of springback were achieved by tuning the contact pressure of a hydraulically driven tool with the local and selective heating of the bending zone by irradiation with a high power diode laser. First, the role of laser operational parameters, namely power, scanning speed and number of passes, in metal bending was investigated, allowing to identify the most suitable processing window. Second, a custom-built equipment to measure the bending angle during the forming process, together with the metal temperature, was implemented. Real-time monitoring of the bending angle and temperature allowed to evaluate the continuous evolution of the geometry of the metal substrates during the external force laser-assisted bending process. Experimental results showed both metal sheets could be bent to high angles with very low fillet radii by the appropriate combination of the tooling contact pressure and selective laser heating of the bending zone. Laser heating also reduces the risk of rupture in both metals during bending at high angles, limits the springback extent up to 10 times on titanium and 30 times on aluminum in comparison with conventional bending process and does not affect significantly the visual appearance of the bending zone.

  18. Excimer laser induced plasma for aluminum alloys surface carburizing

    NASA Astrophysics Data System (ADS)

    Fariaut, F.; Boulmer-Leborgne, C.; Le Menn, E.; Sauvage, T.; Andreazza-Vignolle, C.; Andreazza, P.; Langlade, C.

    2002-01-01

    Currently, while light alloys are useful for automotive industries, their weak wear behavior is a limiting factor. The excimer laser carburizing process reported here has been developed to enhance the mechanical and chemical properties of aluminum alloys. An excimer laser beam is focused onto the alloy surface in a cell containing 1 bar methane or/and propylene gas. A vapor plasma expands from the surface, the induced shock wave dissociates and ionizes the ambient gas. Carbon atoms diffuse into the plasma in contact with the irradiated surface. An aluminum carbide layer is created by carbon diffusion in the surface liquid layer during the recombination phase of the plasma.

  19. 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.

  20. 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.

  1. Microstructure Development and Characteristics of Semisolid Aluminum Alloys

    SciTech Connect

    Merton Flemings; srinath Viswanathan

    2001-05-15

    A drop forge viscometer was employed to investigate the flow behavior under very rapid compression rates of A357, A356 diluted with pure aluminum and Al-4.5%Cu alloys. The A357 alloys were of commercial origin (MHD and SIMA) and the rheocast, modified A356 and Al-4.5Cu alloys were produced by a process developed at the solidification laboratory of MIT.

  2. 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.

  3. Thermoelectrical power analysis of precipitation in 6013 aluminum alloy

    SciTech Connect

    Abdala, M.R.W.S.; Garcia de Blas, J.C. Acselrad, O.

    2008-03-15

    The 6013 aluminum alloy was first developed for application in the aircraft industry and, more recently, as a replacement option for the use of the 6061 alloy in the automotive industry. The present work describes the evolution of the process of formation and dissolution of different kinds of precipitates in 6013 aluminum alloy, subjected to different conditions of heat treatment, using for this purpose measurements of thermoelectrical power, Vickers microhardness and differential scanning calorimeter (DSC). Although in the last years many works have been published on the use of thermoelectrical power (TEP) measurements for the analysis of precipitation process in traditional alloys such as 6061, there is still little information related to 6013 alloy. The results obtained are compared with a previous characterization work on the same alloy using transmission electron microscopy. It was observed that TEP measurements are very sensitive to precipitation phenomena in this alloy, and it has been found that there is an inverse relation between TEP and Vickers microhardness values, which allowed proposing a precipitation sequence for 6013 aluminum alloy.

  4. Influence of Process Parameters on Laser Weld Characteristics in Aluminum Alloys

    DTIC Science & Technology

    1988-08-01

    1 1󈧚 , 4 4 2.1.2 Alloying Element Vaporization Alloying elements added to aluminum for improving the mechanical properties and corrosion...effects the properties of the base metal surrounding the weld zone called the heat affected zone (HAZ). In the non-heat treatable aluminum alloys in the...Hydrogen in Aluminum . Magnesium, Copper, and Their Alloys . Int. Metall. Reviews, Review 201, 20:166-184. 31. Hatch, J.E. 1984. Aluminum , Properties and

  5. 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.

  6. METHOD OF ALLOYING REACTIVE METALS WITH ALUMINUM OR BERYLLIUM

    DOEpatents

    Runnalls, O.J.C.

    1957-10-15

    A halide of one or more of the reactive metals, neptunium, cerium and americium, is mixed with aluminum or beryllium. The mass is heated at 700 to 1200 deg C, while maintaining a substantial vacuum of above 10/sup -3/ mm of mercury or better, until the halide of the reactive metal is reduced and the metal itself alloys with the reducing metal. The reaction proceeds efficiently due to the volatilization of the halides of the reducing metal, aluminum or beryllium.

  7. Characterization of Nanocrystalline Aluminum Alloy 5083 Powders Produced by Cryogenic Attrition

    DTIC Science & Technology

    2014-11-01

    Characterization of Nanocrystalline Aluminum Alloy 5083 Powders Produced by Cryogenic Attrition by Tiffany Ngo ARL-TN-0643...November 2014 Characterization of Nanocrystalline Aluminum Alloy 5083 Powders Produced by Cryogenic Attrition Tiffany Ngo Weapons and...3. DATES COVERED (From - To) August 2014 4. TITLE AND SUBTITLE Characterization of Nanocrystalline Aluminum Alloy 5083 Powders Produced by

  8. Thermodynamics of Titanium-Aluminum-Oxygen Alloys Studied

    NASA Technical Reports Server (NTRS)

    Copland, Evan H.; Jacobson, Nathan S.

    2001-01-01

    Titanium-aluminum alloys are promising intermediate-temperature alloys for possible compressor applications in gas-turbine engines. These materials are based on the a2-Ti3Al + g-TiAl phases. The major issue with these materials is high oxygen solubility in a2-Ti3Al, and oxidation of unsaturated alloys generally leads to mixed non-protective TiO2+Al2O3 scales. From phase diagram studies, oxygen saturated a2-Ti3Al(O) is in equilibrium with Al2O3; however, oxygen dissolution has a detrimental effect on mechanical properties and cannot be accepted. To better understand the effect of oxygen dissolution, we examined the thermodynamics of titanium-aluminum-oxygen alloys.

  9. The effects of aluminum alloy compositions in DIMOX process

    SciTech Connect

    Kim, Chang Wook; Kim, Cheol Soo

    1996-12-31

    Al{sub 2}O{sub 3}-Al composites have been produced by the directed oxidation of binary and ternary aluminum alloys. The Mg, Si, Zn, Sn, Cu, Ni, Ca and Ce have been investigated as alloying elements. The oxidation amount of Al-1wt%Mg alloy was more than that of Al-3wt%Mg alloy. The ternary systems such as Al-Mg-(Si, Sn) alloys were fabricated in the form of porous composites with large amount of oxidation. The amount of oxidation in Al-Mg-(Cu, Ni) was relatively less than that in Al-Mg-(Si, Sn) with some micro pores. Al{sub 2}O{sub 3}-Al composite is always locally growing in Al-xMg-xZn alloys at 1200{degrees}C.

  10. Microstructural Characterization of Aluminum-Lithium Alloys 1460 and 2195

    NASA Technical Reports Server (NTRS)

    Wang, Z. M.; Shenoy, R. N.

    1998-01-01

    Transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) techniques were employed to characterize the precipitate distributions in lithium-containing aluminum alloys 1460 and 2195 in the T8 condition. TEM examinations revealed delta prime and T1 as the primary strengthening precipitates in alloys 1460 and 2195 respectively. TEM results showed a close similarity of the Russian alloy 1460 to the U.S. alloy 2090, which has a similar composition and heat treatment schedule. DSC analyses also indicate a comparable delta prime volume fraction. TEM study of a fractured tensile sample of alloy 1460 showed that delta prime precipitates are sheared by dislocations during plastic deformation and that intense stress fields arise at grain boundaries due to planar slip. Differences in fracture toughness of alloys 1460 and 2195 are rationalized on the basis of a literature review and observations from the present study.

  11. Aluminum alloy 6013 sheet for new U. S. Navy aircraft

    SciTech Connect

    Kaneko, R.S.; Bakow, L.; Lee, E.W. Naval Air Development Center, Warminster, PA )

    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. 5 refs.

  12. Environment assisted degradation mechanisms in aluminum-lithium alloys

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Stoner, Glenn E.; Swanson, Robert E.

    1988-01-01

    Section 1 of this report records the progress achieved on NASA-LaRC Grant NAG-1-745 (Environment Assisted Degradation Mechanisms in Al-Li Alloys), and is based on research conducted during the period April 1 to November 30, 1987. A discussion of work proposed for the project's second year is included. Section 2 provides an overview of the need for research on the mechanisms of environmental-mechanical degradation of advanced aerospace alloys based on aluminum and lithium. This research is to provide NASA with the basis necessary to permit metallurgical optimization of alloy performance and engineering design with respect to damage tolerance, long term durability and reliability. Section 3 reports on damage localization mechanisms in aqueous chloride corrosion fatigue of aluminum-lithium alloys. Section 4 reports on progress made on measurements and mechanisms of localized aqueous corrosion in aluminum-lithium alloys. Section 5 provides a detailed technical proposal for research on environmental degradation of Al-Li alloys, and the effect of hydrogen in this.

  13. Aluminum and aluminum alloys as sources of hydrogen for fuel cell applications

    NASA Astrophysics Data System (ADS)

    Soler, Lluís; Macanás, Jorge; Muñoz, Maria; Casado, Juan

    Production of hydrogen using aluminum and aluminum alloys with aqueous alkaline solutions is studied. This process is based on aluminum corrosion, consuming only water and aluminum which are cheaper raw materials than other compounds used for in situ hydrogen generation, such as chemical hydrides. In principle, this method does not consume alkali because the aluminate salts produced in the hydrogen generation undergo a decomposition reaction that regenerates the alkali. As a consequence, this process could be a feasible alternative for hydrogen production to supply fuel cells. Preliminary results showed that an increase of base concentration and working solution temperature produced an increase of hydrogen production rate using pure aluminum. Furthermore, an improvement of hydrogen production rates and yields was observed varying aluminum alloys composition and increasing their reactive surface, with interesting results for Al/Si and Al/Co alloys. The development of this idea could improve yields and reduce costs in power units based on fuel cells which use hydrides as raw material for hydrogen production.

  14. Task Order Number 5TS5702D035P: Testing Alternative Aircraft and Runway/Taxiway Deicers - Phase 2

    DTIC Science & Technology

    2004-06-01

    Aluminum-Bronze Alloy (AMS 4640 MT3 AZ91E Cast Magnesium Alloy (AMS 4446 MT4 7075-T6 Bare Aluminum Alloy (AMS 4045) MT5 Polymer Matrix Composites 977-3 Epoxy...Corrosion Details Substrate I A286 4140 Steel C630 AZ91E -T6 7075-T6 I Steel Aluminum- Cast Bare Bronze Alloy Magnesium Aluminum Deicer J.. I I Alloy Alloy...Continued) Substrate I A286 4140 Steel C630 AZ91E - T6 707S-T6 Steel Aluminum- Cast Bare I Bronze Alloy .Magnesium Aluminum Deicer ,J.. ’ , Alloy

  15. Interpretation of aluminum-alloy weld radiography

    NASA Technical Reports Server (NTRS)

    Duren, P. C.; Risch, E. R.

    1971-01-01

    Report proposes radiographic terminology standardization which allows scientific interpretation of radiographic films to replace dependence on individual judgement and experience. Report includes over 50 photographic pages where radiographs of aluminum welds with defects are compared with prepared weld sections photomacrographs.

  16. 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.

  17. Tin soldering of aluminum and its alloys

    NASA Technical Reports Server (NTRS)

    Gallo, Gino

    1921-01-01

    A method is presented for soldering aluminum to other metals. The method adopted consists of a galvanic application to the surface of the light-metal parts to be soldered, of a layer of another metal, which, without reacting electrolytically on the aluminum, adheres strongly to the surface to which it is applied, and is, on the other hand, adapted to receive the soft solder. The metal found to meet the criteria best was iron.

  18. Characteristics of aluminum alloy microplastic deformation in different structural states

    SciTech Connect

    Seregin, G.V.; Efimenko, L.L.; Leonov, M.V.

    1995-07-01

    The solution to the problem of improving the mechanical properties (including cyclic strength) of structural materials is largely dependent on our knowledge of the laws governing the development of microplastic deformations in them. The effect of heat and mechanical treatment on the elastoplastic properties and fatigue resistance of the commercial aluminum alloys AK4-1 and D16 is analyzed.

  19. Aluminum alloy material structure impact localization by using FBG sensors

    NASA Astrophysics Data System (ADS)

    Zhu, Xiubin

    2014-12-01

    The aluminum alloy structure impact localization system by using fiber Bragg grating (FBG) sensors and impact localization algorithm was investigated. A four-FBG sensing network was established. And the power intensity demodulation method was initialized employing the narrow-band tunable laser. The wavelet transform was used to weaken the impact signal noise. And the impact signal time difference was extracted to build the time difference localization algorithm. At last, a fiber Bragg grating impact localization system was established and experimentally verified. The experimental results showed that in the aluminum alloy plate with the 500 mm*500 mm*2 mm test area, the maximum and average impact abscissa localization errors were 11 mm and 6.25 mm, and the maximum and average impact ordinate localization errors were 9 mm and 4.25 mm, respectively. The fiber Bragg grating sensors and demodulation system are feasible to realize the aviation aluminum alloy material structure impact localization. The research results provide a reliable method for the aluminum alloy material structure impact localization.

  20. 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

  1. Effects of aluminum-copper alloy filtration on photon spectra, air kerma rate and image contrast.

    PubMed

    Gonçalves, Andréa; Rollo, João Manuel Domingos de Almeida; Gonçalves, Marcelo; Haiter Neto, Francisco; Bóscolo, Frab Norberto

    2004-01-01

    This study evaluated the performance of aluminum-copper alloy filtration, without the original aluminum filter, for dental radiography in terms of x-ray energy spectrum, air kerma rate and image quality. Comparisons of various thicknesses of aluminum-copper alloy in three different percentages were made with aluminum filtration. Tests were conducted on an intra-oral dental x-ray machine and were made on mandible phantom and on step-wedge. Depending on the thickness of aluminum-copper alloy filtration, the beam could be hardened and filtrated. The use of the aluminum-copper alloy filter resulted in reductions in air kerma rate from 8.40% to 47.33%, and indicated the same image contrast when compared to aluminum filtration. Aluminum-copper alloy filtration may be considered a good alternative to aluminum filtration.

  2. Development Program for Natural Aging Aluminum Casting Alloys

    SciTech Connect

    Dr. Geoffrey K. Sigworth

    2004-05-14

    A number of 7xx aluminum casting alloys are based on the ternary Al-Zn-Mg system. These alloys age naturally to high strength at room temperature. A high temperature solution and aging treatment is not required. Consequently, these alloys have the potential to deliver properties nearly equivalent to conventional A356-T6 (Al-Si-Mg) castings, with a significant cost saving. An energy savings is also possible. In spite of these advantages, the 7xx casting alloys are seldom used, primarily because of their reputation for poor castibility. This paper describes the results obtained in a DOE-funded research study of these alloys, which is part of the DOE-OIT ''Cast Metals Industries of the Future'' Program. Suggestions for possible commercial use are also given.

  3. Cryogenic mechanical properties of low density superplastic aluminum alloys

    SciTech Connect

    Verzasconi, S.L.

    1989-05-01

    Two alloy systems, mainly Al-Li-Cu and Al-Mg-Sc, were studied in this work. Both of these systems have been shown to be superplastically formable in the conditions chosen, and both provide a significant density reduction over a currently used aluminum cryogenic fuel tankage material, 2219. The Al-Mg-Sc alloy provides over 50 percent of the density reduction of 2090 over 2219. In addition to lower density, Al-Li alloys have a higher elastic modulus (stiffness) than conventional aerospace alloys. The main purpose of this work is to characterize the cryogenic strength and toughness of several Al-Cu-Li and Al-Mg-Sc alloys. In addition, the microstructures and fracture surfaces are characterized and related to these properties where possible. 43 refs.

  4. The Effect of Alloy Additions on Superplasticity in Thermomechanically Processed High Magnesium Aluminum-Magnesium Alloys.

    DTIC Science & Technology

    1984-12-01

    AD-Ri55 142 THE EFFECT OF ALLOY ADDITIONS ON SUPERPLASTICITY IN I/2 THERMOMECHANICALLY PR-.(U) NAVAL POSTGRADUATE SCHOOL UNCLSSIIED MONTEREY CA R J...Ln Monterey, California DTr J U N 1985 * THESIS THE EFFECT OF ALLOY ADDITIONS ON SUPERPLASTICITY IN THERMOMECHANICALLY PROCESSED HIGH MAGNESIUM *0...ALUMINUM-MAGNESIUM ALLOYS >by 0 (Richard J. Self December 1984 C-31 Thesis Advisor: Terry McNelley Approved for public release; distribution is unlimited

  5. Reduction of Oxidative Melt Loss of Aluminum and Its Alloys

    SciTech Connect

    Dr. Subodh K. Das; Shridas Ningileri

    2006-03-17

    This project led to an improved understanding of the mechanisms of dross formation. The microstructural evolution in industrial dross samples was determined. Results suggested that dross that forms in layers with structure and composition determined by the local magnesium concentration alone. This finding is supported by fundamental studies of molten metal surfaces. X-ray photoelectron spectroscopy data revealed that only magnesium segregates to the molten aluminum alloy surface and reacts to form a growing oxide layer. X-ray diffraction techniques that were using to investigate an oxidizing molten aluminum alloy surface confirmed for the first time that magnesium oxide is the initial crystalline phase that forms during metal oxidation. The analytical techniques developed in this project are now available to investigate other molten metal surfaces. Based on the improved understanding of dross initiation, formation and growth, technology was developed to minimize melt loss. The concept is based on covering the molten metal surface with a reusable physical barrier. Tests in a laboratory-scale reverberatory furnace confirmed the results of bench-scale tests. The main highlights of the work done include: A clear understanding of the kinetics of dross formation and the effect of different alloying elements on dross formation was obtained. It was determined that the dross evolves in similar ways regardless of the aluminum alloy being melted and the results showed that amorphous aluminum nitride forms first, followed by amorphous magnesium oxide and crystalline magnesium oxide in all alloys that contain magnesium. Evaluation of the molten aluminum alloy surface during melting and holding indicated that magnesium oxide is the first crystalline phase to form during oxidation of a clean aluminum alloy surface. Based on dross evaluation and melt tests it became clear that the major contributing factor to aluminum alloy dross was in the alloys with Mg content. Mg was

  6. 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

  7. Crack Initiation and Growth Behavior at Corrosion Pit in 2024-T3 Aluminum Alloy

    DTIC Science & Technology

    2014-09-01

    aluminum alloy [35] ... 26 Table 3.2: Mechanical properties of a typical sample of 2024-T3 aluminum alloy [35]. 26 Table 3.3: Details of test...mechanical properties . Table 3.1: Component materials of a typical sample of 2024-T3 aluminum alloy [35]. Element %component Aluminum , Al 90.7-94.7...Silicon, Si Max0.5 Titanium, Ti Max 0.15 Zinc, Zn Max0.25 Table 3.2: Mechanical properties of a typical sample of 2024-T3 aluminum alloy

  8. Hydrogen interactions in aluminum-lithium alloys

    NASA Technical Reports Server (NTRS)

    Smith, S. W.; Scully, J. R.

    1991-01-01

    A program is described which seeks to develop an understanding of the effects of dissolved and trapped hydrogen on the mechanical properties of selected Al-Li-Cu-X alloys. A proposal is made to distinguish hydrogen (H2) induced EAC from aqueous dissolution controlled EAC, to correlate H2 induced EAC with mobile and trapped concentrations, and to identify significant trap sites and hydride phases (if any) through use of model alloys and phases. A literature review shows three experimental factors which have impeded progress in the area of H2 EAC for this class of alloys. These are as listed: (1) inter-subgranular fracture in Al-Li alloys when tested in the S-T orientation in air or vacuum make it difficult to readily detect H2 induced fracture based on straight forward changes in fractography; (2) the inherently low H2 diffusivity and solubility in Al alloys is further compounded by a native oxide which acts as a H2 permeation barrier; and (3) H2 effects are masked by dissolution assisted processes when mechanical testing is performed in aqueous solutions.

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    The hot corrosion resistance of nickel-chromium-aluminum alloys 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. From these equations corrosion isopleths were prepared. Compositional regions with the best hot corrosion resistance were identified.

  10. Approaches for mechanical joining of 7xxx series aluminum alloys

    NASA Astrophysics Data System (ADS)

    Jäckel, M.; Grimm, T.; Landgrebe, D.

    2016-10-01

    This paper shows a numerical and experimental analysis of the different problems occurring during or after the conventional self-pierce riveting with semi-tubular and solid rivets of the high strength aluminum alloy EN AW-7021 T4. Furthermore this paper describes different pre-process methods by which the fracture in the high strength aluminum, caused by the self-pierce riveting processes, can be prevented and proper joining results are achieved. On this basis, the different approaches are compared regarding joint strength.

  11. 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.

  12. Cast Aluminum Alloy for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2003-01-01

    Originally developed by NASA as high performance piston alloys to meet U.S. automotive legislation requiring low exhaust emission, the novel NASA alloys now offer dramatic increase in tensile strength for many other applications at elevated temperatures from 450 F (232 C) to about 750 F (400 C). It is an ideal low cost material for cast automotive components such as pistons, cylinder heads, cylinder liners, connecting rods, turbo chargers, impellers, actuators, brake calipers and rotors. It can be very economically produced from conventional permanent mold, sand casting or investment casting, with silicon content ranging from 6% to 18%. At high silicon levels, the alloy exhibits excellent dimensional stability, surface hardness and wear resistant properties.

  13. 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.

  14. Laser assisted high entropy alloy coating on aluminum: Microstructural evolution

    SciTech Connect

    Katakam, Shravana; Joshi, Sameehan S.; Mridha, Sanghita; Mukherjee, Sundeep; Dahotre, Narendra B.

    2014-09-14

    High entropy alloy (Al-Fe-Co-Cr-Ni) coatings were synthesized using laser surface engineering on aluminum substrate. Electron diffraction analysis confirmed the formation of solid solution of body centered cubic high entropy alloy phase along with phases with long range periodic structures within the coating. Evolution of such type of microstructure was a result of kinetics associated with laser process, which generates higher temperatures and rapid cooling resulting in retention of high entropy alloy phase followed by reheating and/or annealing in subsequent passes of the laser track giving rise to partial decomposition. The partial decomposition resulted in formation of precipitates having layered morphology with a mixture of high entropy alloy rich phases, compounds, and long range ordered phases.

  15. Chromate Conversion Coating of Aluminum Alloys

    DTIC Science & Technology

    1975-07-10

    a sodium sulfate-nitric acid solution sometimes used to clean aluminum prior to spotwelding. Immersion times were varied in the chromate-sulfate...Good results were also obtained with sodium sulfate-nitric acid and an 8 minute treatment in one non-chromete proprietary solution. Average resis...molybdate or tungstate salts with the ferricyanide ion considered to be the most effective accelerator. Water for Bath Make-Up and Rinsing It is very

  16. Friction and wear of titanium alloys and copper alloys sliding against titanium 6-percent-aluminum - 4-percent-vanadium alloy in air at 430 C

    NASA Technical Reports Server (NTRS)

    Wisander, D. W.

    1976-01-01

    Experiments were conducted to determine the friction and wear characteristics of aluminum bronzes and copper-tin, titanium-tin, and copper-silver alloys sliding against a titanium-6% aluminum-4% vanadium alloy (Ti-6Al-4V). Hemispherically tipped riders of aluminum bronze and the titanium and copper alloys were run against Ti-6Al-4V disks in air at 430 C. The sliding velocity was 13 cm/sec, and the load was 250 g. Results revealed that high tin content titanium and copper alloys underwent significantly less wear and galling than commonly used aluminum bronzes. Also friction force was less erratic than with the aluminum bronzes.

  17. Evaluation and control of environmental corrosion for aluminum and steel alloys

    NASA Technical Reports Server (NTRS)

    Franklin, D. B.

    1977-01-01

    Corrosion protection systems for aerospace application and the effects of surface treatments and methods of controlling stress corrosion are evaluated. Chromate pigmented systems were found to be most effective for aluminum alloys; zinc-rich coatings gave the greatest protection to steel alloys. Various steel and aluminum alloys are rated for stress corrosion resistance.

  18. Statistical Analysis of Strength Data for an Aerospace Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Neergaard, Lynn; Malone, Tina; Gentz, Steven J. (Technical Monitor)

    2000-01-01

    Aerospace vehicles are produced in limited quantities that do not always allow development of MIL-HDBK-5 A-basis design allowables. One method of examining production and composition variations is to perform 100% lot acceptance testing for aerospace Aluminum (Al) alloys. This paper discusses statistical trends seen in strength data for one Al alloy. A four-step approach reduced the data to residuals, visualized residuals as a function of time, grouped data with quantified scatter, and conducted analysis of variance (ANOVA).

  19. Statistical Analysis of Strength Data for an Aerospace Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Neergaard, L.; Malone, T.

    2001-01-01

    Aerospace vehicles are produced in limited quantities that do not always allow development of MIL-HDBK-5 A-basis design allowables. One method of examining production and composition variations is to perform 100% lot acceptance testing for aerospace Aluminum (Al) alloys. This paper discusses statistical trends seen in strength data for one Al alloy. A four-step approach reduced the data to residuals, visualized residuals as a function of time, grouped data with quantified scatter, and conducted analysis of variance (ANOVA).

  20. A Positron Annihilation Study of Corrosion of Aluminum and Aluminum Alloy by NaOH

    NASA Astrophysics Data System (ADS)

    Wu, Y. C.; Zhai, T.; Coleman, P. G.

    2012-08-01

    Corrosion of fully-annealed pure aluminum and a continuous-cast AA2037 aluminum alloy (solutionized and water quenched) in a 1M NaOH solution for various periods of time were analyzed with positron beam-based Doppler broadening spectroscopy. By varying the energy of the incident positron beam, corrosion-induced defects at different depths from the surface were detected. It was found that the Doppler-broadened annihilation line-width parameter was significantly increased near the surface of pure aluminum after corrosion, probably due to the interaction between positrons and nanometer-sized voids formed near the aluminum surface during corrosion. Examination by atomic force microscopy indicated that many pits were formed on the aluminum surface after corrosion. In contrast, a significant decrease in the line-width parameter was observed in AA2037 alloy after corrosion and interpreted as being caused by copper enrichment at the metal-oxide interface during corrosion; such enrichment at large cavity sites was confirmed by energy dispersion spectrometry.

  1. Welding high-strength aluminum alloys at the Paton Institute

    SciTech Connect

    Kuchuk, Yatsenko, S.I.; Cherednichok, V.T.; Semenov, L.A. )

    1993-07-01

    The choice of the flash method for welding aluminum-alloy sections was governed first of all by the possibility of producing homogeneous-structure joints with the minimum amount of possible discontinuities and an insignificant metal strength loss in the welding zone. The aluminum alloy welding technology under consideration relies on the method of flash welding without using any protective atmospheres. The reason is first of all that a complex cross-sectional shape of workpieces being joined, their configuration and considerable overall dimensions make it difficult to use chambers of any type. Besides, conducted studies ascertained that in flash welding, in contrast to various fusion welding processes, the use of protective atmospheres or a vacuum is of little benefit. Here are the results of studying the specifics of thermal and electric processes in flashing, the physical features of weld joint formation, the basics of the welding technology, and the characteristics of the equipment.

  2. Small Crack Growth and Fatigue Life Predictions for High-Strength Aluminium Alloys. Part 1; Experimental and Fracture Mechanics Analysis

    NASA Technical Reports Server (NTRS)

    Wu, X. R.; Newman, J. C.; Zhao, W.; Swain, M. H.; Ding, C. F.; Phillips, E. P.

    1998-01-01

    The small crack effect was investigated in two high-strength aluminium alloys: 7075-T6 bare and LC9cs clad alloy. Both experimental and analytical investigations were conducted to study crack initiation and growth of small cracks. In the experimental program, fatigue tests, small crack and large crack tests A,ere conducted under constant amplitude and Mini-TWIST spectrum loading conditions. A pronounced small crack effect was observed in both materials, especially for the negative stress ratios. For all loading conditions, most of the fatigue life of the SENT specimens was shown to be crack propagation from initial material defects or from the cladding layer. In the analysis program, three-dimensional finite element and A weight function methods were used to determine stress intensity factors and to develop SIF equations for surface and corner cracks at the notch in the SENT specimens. A plastisity-induced crack-closure model was used to correlate small and large crack data, and to make fatigue life predictions, Predicted crack-growth rates and fatigue lives agreed well with experiments. A total fatigue life prediction method for the aluminum alloys was developed and demonstrated using the crack-closure model.

  3. Deformation behavior of submicrocrystalline aluminum alloys during dynamic loading

    NASA Astrophysics Data System (ADS)

    Brodova, I. G.; Petrova, A. N.; Razorenov, S. V.; Plekhov, O. P.; Shorokhov, E. V.

    2016-04-01

    The structure and the mechanical properties of aluminum V95 and AMts alloys with various grain sizes (from micron to submicron) are studied in a wide range of strain rates (from 10-3 to 105 s-1). Submicrocrystalline (200-600 nm) materials are formed by dynamic channel-angular pressing at a strain rate of 105 s-1 using a pulsed power source.

  4. Corrosion of Aluminum Alloys by IRFNA

    DTIC Science & Technology

    1990-02-24

    and electropolishing and anodising, have been studied. aNeither had a significant long term effect on the corrosion rate of 2014 alumninium alloy in... steel spatula. (iv) The cell was assembled and raw eghed, the charge of galled Acid being determined by difference. Two additional bottom-working...The anodiuing solution was 1swt% sulphuric acid And the conditions were 25oC, 1 Mwm, 12V. The anodic oxide film waS scaled in delonised water (30

  5. The Development of Aluminum-Lithium Alloys.

    DTIC Science & Technology

    1980-07-31

    Metallurgy Sander A. Levy, Director Department of Metallurgical Services and Ingot Casting Technology __j: Grant E. Spangle $, Gereral Director bd...of the Aqeinq Mechanism of the Alloy Al-Li," translated from Fiz. Metal Metalloved., V. 42, N. 3, 1976 , pp. 546-556. [8] B. Noble and G. E. Thompson...34 translated from Fiz. Metal Metalloved., 42, N. 5, 1976 , pp. 1021-1028. -159- [19] Z. A. Sviderskaya, E. S. Kadaner, N. I. Turkina, and V. I

  6. Welding of aluminum alloy with high power direct diode laser

    NASA Astrophysics Data System (ADS)

    Abe, Nobuyuki; Morikawa, Atsuhito; Tsukamoto, Masahiro; Maeda, Koichi; Namba, Keizo

    2003-06-01

    Characterized by high conversion efficiency, small size, light weight and a long lifetime, high power diode lasers are currently being developed for application to various types of metal fabrication, such as welding. In this report, a 4kW high power direct diode laser was used to weld aluminum alloys, which are the focus of increasing attention from the automobile industry because of their light weight, high formability and easy recyclability. The applicability of a direct diode laser to aluminum alloy bead-on plate, butt and lap-fillet welding was studied under various welding conditions. A sound bead without cracks was successfully obtained when 1 mm thick aluminum alloy was welded by bead-on welding at a speed of 12m/min. Moreover, the bead cross section was heat conduction welding type rather than the keyhole welding type of conventional laser welding. Investigation of the welding phenomena with a high-speed video camera showed no spattering or laser plasma, so there was no problem with laser plasma damaging the focusing lens despite the diode laser's short focusing distance.

  7. Russian aluminum-lithium alloys for advanced reusable spacecraft

    NASA Astrophysics Data System (ADS)

    Charette, Ray O.; Leonard, Bruce G.; Bozich, William F.; Deamer, David A.

    1998-01-01

    Cryotanks that are cost-affordable, robust, fuel-compatible, and lighter weight than current aluminum design are needed to support next-generation launch system performance and operability goals. The Boeing (McDonnell Douglas Aerospace-MDA) and NASA's Delta Clipper-Experimental Program (DC-XA) flight demonstrator test bed vehicle provided the opportunity for technology transfer of Russia's extensive experience base with weight-efficient, highly weldable aluminum-lithium (Al-Li) alloys for cryogenic tank usage. As part of NASA's overall reusable launch vehicle (RLV) program to help provide technology and operations data for use in advanced RLVs, MDA contracted with the Russian Academy of Sciences (RAS/IMASH) for design, test, and delivery of 1460 Al-Li alloy liquid oxygen (LO2) cryotanks: one for development, one for ground tests, and one for DC-XA flight tests. This paper describes the development of Al-Li 1460 alloy for reusable LO2 tanks, including alloy composition tailoring, mechanical properties database, forming, welding, chemical milling, dissimilar metal joining, corrosion protection, completed tanks proof, and qualification testing. Mechanical properties of the parent and welded materials exceeded expectations, particularly the fracture toughness, which promise excellent reuse potential. The LO2 cryotank was successfully demonstrated in DC-XA flight tests.

  8. Activity and diffusion of metals in binary aluminum alloys

    SciTech Connect

    Jao, C. S.

    1980-12-01

    To determine the activity of zinc in Zn-Al alloys, the electromotive force (emf) of the cell: Zn/ZnCl/sub 2/-KC1 (eut)/Zn,Al was measured at temperatures between 569.5 K (296.5C) and 649.5 K (376.5C). The applicability of a two-suffix Margules equation was demonstrated, in good agreement with theoretical expectations. The diffusion coefficient of Zn in Al determined from a planar diffusion model for the experimental data was about 3 x 10/sup -10/ cm/sup 2//sec to 2 x 10/sup -9/ cm/sup 2//sec in the range of temperature studied. This is higher than that found in the literature. The most plausible reason appears to be the high alumina concentration in the working electrode because of partial oxidation. Oxidation of the alloying metals was the primary cause of poor alloying between calcium/or zinc and aluminum, thereby frustrating similar measurements at a Ca-Al/or Zn-Al alloy. The literature on the activity of calcium and zinc is aluminum is reviewed.

  9. Characteristics of laser surface melted aluminum alloys.

    PubMed

    Weinman, L S; Kim, C; Tucker, T R; Metzbower, E A

    1978-03-15

    Specimens of Al-Fe 1-4 w/o, 2024 and 6061 Al have been surface melted with a pulsed Nd-glass laser. A TEM and SEM study showed that the dendrite spacings were from 2500 A to 4000 A which corresponds to a cooling rate of over 10(6) degrees C/sec. Melt depths obtained were in the range of 30-100 microm. No significant surface vaporization was observed at energy densities up to 440 J/cm(2). Fracture surfaces of the commerical alloys demonstrated elongated porosity in the melt areas, probably due to internal hydrogen.

  10. Diffusion bonding of Al7075 alloy to titanium aluminum vanadate alloy

    NASA Astrophysics Data System (ADS)

    Alhazaa, Abdulaziz Nasser

    The aluminum alloy (Al7075) and titanium alloy (Ti-6Al-4V) are used in a variety of applications in the aerospace industry. However, the high cost of Ti-6Al-4V alloy has been a major factor which has limited its use and therefore, the ability to join Al7075 alloy to Ti-6Al-4V alloy can provide a product that is less costly, but retains the high strength and light weight properties necessary for the transport industry. However, the large difference in the physical properties between these two alloys prevents the use of conventional joining techniques such as fusion welding to join these dissimilar alloys. Therefore, the diffusion bonding technique was used to join Al7075 alloy to Ti-6Al-4V alloy with the objective of minimizing microstructural changes of the two alloys during the bonding process. In this thesis, solid state and liquid phase bonding processes were undertaken. Solid state bonding was employed without interlayers and was successful at 510°C and 7 MPa. The bond interface showed an absence of the oxides due to the dissolution of oxygen into the titanium solution. Bonds made using copper interlayers at a temperature sufficient enough to form eutectic liquid formation between copper and aluminum were produced. The intermetallics theta(Al2Cu), S(Al2CuMg) and T(Al2Mg3Zn3) were identified at the aluminum interface while Cu3Ti2 intermetallic was identified at the titanium interface. Bonds made using tin based alloys interlayers and copper coatings were successful and gave the highest shear strength. The eutectic formation on the Al7075 alloy was responsible for joint formation at the aluminum interface while the formation of Sn3Ti5 intermetallic was responsible for the joint formation at titanium interface. The corrosion rate of the bonds decreased with increasing bonding time for joints made using the tin based interlayer in 3% NaCl solution. However, the presence of copper within the joint increased the corrosion rate of the bonds and this was attributed to

  11. 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.

  12. Assessment of Accelerated Tests Compared to Beachfront Test and Proposed Evaluation Method

    DTIC Science & Technology

    2009-09-03

    corrosion tests to beachfront test NCAP Data Assessment Data set includes: – 4 aluminum alloys: 2024, 7075, 2219 , 5083 – 9 conversion coatings...2024-T3 Alodine 1600 2024-T3 TCP-IC 7075- T6 Alodine 1600 7075- T6 TCP-IC 18 Months Exposure at KSC 20X view of surface As is Cleaned Unpainted Corrosion ...Certification Program (ESTCP) funded project entitled “Non-Chromate Aluminum Pretreatments” (NCAP) – Funding began in 2000, ended 2004 for Phase I

  13. 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.

  14. Crack Repair in Aerospace Aluminum Alloy Panels by Cold Spray

    NASA Astrophysics Data System (ADS)

    Cavaliere, P.; Silvello, A.

    2017-02-01

    The cold-spray process has recently been recognized as a very useful tool for repairing metallic sheets, achieving desired adhesion strengths when employing optimal combinations of material process parameters. We present herein the possibility of repairing cracks in aluminum sheets by cold spray. A 2099 aluminum alloy panel with a surface 30° V notch was repaired by cold spraying of 2198 and 7075 aluminum alloy powders. The crack behavior of V-notched sheets subjected to bending loading was studied by finite-element modeling (FEM) and mechanical experiments. The simulations and mechanical results showed good agreement, revealing a remarkable K factor reduction, and a consequent reduction in crack nucleation and growth velocity. The results enable prediction of the failure initiation locus in the case of repaired panels subjected to bending loading and deformation. The stress concentration was quantified to show how the residual stress field and failure are affected by the mechanical properties of the sprayed materials and by the geometrical and mechanical properties of the interface. It was demonstrated that the crack resistance increases more than sevenfold in the case of repair using AA2198 and that cold-spray repair can contribute to increased global fatigue life of cracked structures.

  15. 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.

  16. 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

  17. Aluminum rich alloys for energy storage and conversion

    NASA Astrophysics Data System (ADS)

    Choi, Go

    The recent environmental problem and depletion of natural power resources have intensified the search for clean and renewable energy which has become one of the major issues of the Twenty-first century. Furthermore, global demand for freshwater has been increasing, raising concerns for water insufficiency. The goal of this research is to seek and introduce a viable technology that could potentially solve both energy and water crises. It has been investigated that Al-Ga-In-Sn quaternary system alloys can split water and produce hydrogen and heat. This paper focuses on the aluminum-rich Al-Ga-In-Sn quaternary system alloys, exploring the mystery behind the mechanism. As the paper will show, this technology can be applied to both salt water and sea water, and is thus a potential solution for marine applications and desalination. However, it has been shown that the alloy reacts differently depending on the fabrication method and environmental conditions. Various experiments were conducted to understand this phenomenon. This paper discusses several different reactions caused by various cooling rates and compositions, which effectively changes the crystal structure of the alloy and its liquid phase. Characteristics of the liquid phase define the alloy and determine its applications.

  18. 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.

  19. 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.

  20. Textures, microstructures, anisotropy and formability of aluminum-manganese-magnesium and aluminum-magnesium alloys

    NASA Astrophysics Data System (ADS)

    Liu, Jiantao

    In this dissertation work, the microstructure and texture evolution of continuous cast (CC) and direct chill (DC) cast Al-Mn-Mg (AA 3105 and AA 3015) and Al-Mg (AA 5052) alloys during cold rolling and annealing are systematically investigated. Macrotexture analyses were based on three-dimensional orientation distribution functions (ODFs) calculated from incomplete pole figures from X-ray diffraction by using arbitrarily defined cell (ADC) and series expansion methods. A new technique, electron backscatter diffraction (EBSD), was adopted for microtexture and mesotexture investigation. The anisotropy and formability of Al-Mn-Mg and Al-Mg alloys are correlated to the texture results. For aluminum alloys studied in this work, a stronger Cube orientation is observed in DC hot band than in CC hot band after complete recrystallization. alpha and beta fibers become well developed beyond 50% cold rolling in both CC and DC aluminum alloys. The highest intensity along the beta fiber (skeleton line) is located between the Copper and the S orientations in both materials after high cold rolling reductions. In both CC and DC aluminum alloys, a cell structure develops with the indication of increasing CSL Sigma1 boundaries during the early stages of cold rolling. There is no evidence of the development of twin boundaries (Sigma3, Sigma9, Sigma27a & 27b) in either CC or DC aluminum alloys when the cold rolling reductions are less than 40%. The R and Cube textures are dominant recrystallization texture components in CC and DC AA 5052 alloys. The volume fraction of the Cube component is increased by increasing cold rolling reduction and annealing temperature but not by increasing annealing time while the volume fraction of the R component is only increased by increasing cold rolling reduction. Stronger Cube and R orientations are found at the surface layer than at half-thickness layer of cold rolled hot bands after annealing. The Cube and P textures are dominant recrystallization

  1. Chromate-free talc chemical conversion coatings for aluminum alloys

    SciTech Connect

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

    1993-10-01

    We have found that aluminum alloys exhibit unusual passivity when exposed to alkaline Li-salt solutions. Observed passivity is due to the formation of a polycrystalline Li{sub 2}[Al{sub 2}(OH){sub 6}]{sub 2}{center_dot}CO{sub 3}{center_dot}3H{sub 2}O film on the aluminum surface. This film is persistent in aggressive environments and provides a significant degree of corrosion protection. On this basis, we have developed a simple non-electrolytic method of forming corrosion resistant coatings in alkaline Li-salt solution. This process is procedurally similar to traditional conversion coating methods, offers desirable properties, and has a low toxic hazard. In this paper, coating methods, coating characterization, and coating properties are presented. Results from parallel test performed with a commercial chromate conversion coatings are presented for comparison.

  2. Fatigue damage study in aluminum-2024 T3 alloys

    NASA Technical Reports Server (NTRS)

    Ferguson, Milton W.

    1992-01-01

    The grain structure of aluminum 2024, a commonly used commercial alloy is investigated, and these findings are correlated with the fatigue property of the material. Samples of aluminum 2024 were polished and etched in different reagents. Optical micrographs (at 500X) of samples etched in Keller's reagent revealed grain boundaries as well as some particles present in the microstructure. Normal x-ray scans of samples etched for different intervals of time in Keller's reagent indicate no significant variations in diffraction peak positions; however, the width of the rocking curve increased with the time of etching. These results are consistent with the direct dependence of the width of the rocking curve on the range of grain orientation. Etching removes the preferred orientation layer of the sample produced by polishing; thereby, causing the width to increase.

  3. Chromate-free corrosion resistant conversion coatings for aluminum alloys

    SciTech Connect

    Buchheit, R.G.; Drewien, C.A.; Martinez, M.A.; Stoner, G.E.

    1995-03-01

    Inorganic polycrystalline hydrotalcite, Li{sub 2}[Al{sub 2}(OH){sub 6}]{sub 2}{center_dot}CO{sub 3}{center_dot}3H{sub 2}O, coatings can be formed on aluminum and aluminum alloys by exposure to alkaline lithium carbonate solutions. This process is conducted using methods similar to traditional chromate conversion coating procedures, but does not use or produce toxic chemicals. The coating provides anodic protection and delays the onset of pitting during anodic polarization. Cathodic reactions are also inhibited which may also contribute to corrosion protection. Recent studies have shown that corrosion resistance can be increased by sealing hydrotalcite coated surfaces to transition metal salt solutions including Ce(NO{sub 3}){sub 3}, KMnO{sub 4} and Na{sub 2}MoO{sub 4}. Results from these studies are also reported.

  4. Thermodynamics of iron-aluminum alloys at 1573 K

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Mehrotra, Gopal M.

    1993-01-01

    The activities of iron and aluminum were measured in Fe-Al alloys at 1573 K, using the ion-current-ratio technique in a high-temperature Knudsen cell mass spectrometer. The Fe-Al solutions exhibited negative deviations from ideality over the entire composition range. The activity coefficients gamma(Fe), and gamma(Al) are given by six following equations as a function of mole fraction, X(Fe), X(Al). The results show good agreement with those obtained from previous investigations at other temperatures by extrapolation of the activity data to 1573 K.

  5. 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.

  6. Investigation of High Speed Friction Test for Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Ooki, K.; Takahashi, S.

    2016-08-01

    To shorten the development stage of automobiles, FEM simulation has been applied. It was important to increase the accuracy of the sheet metal simulation results. The friction coefficient between the sheet metal and dies the greatly affected the simulation results. Therefore, apparatus for measuring the friction coefficient with a specific press forming speed (300 mm/s) has been developed. The materials of the sheet metals and dies were aluminum alloys and die steel respectively. It was found that the friction was affected by the difference between the velocity of the sheet metal and that of the dies.

  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. 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.

  9. Column and Plate Compressive Strength of Extruded XB75S-T Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Heimerl, George J.; Roy, J. Albert

    1944-01-01

    Results are presented of tests to determine the column and plate compressive strength of extruded XB75S-T aluminum alloy, and comparative values are shown for 24S-T aluminum-alloy sheet. Stress-strain curves are also given,

  10. The Cryogenic Tensile Properties of an Extruded Aluminum-Beryllium Alloy

    NASA Technical Reports Server (NTRS)

    Gamwell, W. R.

    2002-01-01

    Basic mechanical properties; i.e., ultimate tensile strength, yield strength, percent elongation, and elastic modulus, were obtained for the aluminum-beryllium alloy, AlBeMet162, at cryogenic (-195.5 C (-320 F) and -252.8 C (-423 F)) temperatures. The material evaluated was purchased to the requirements of SAE-AMS7912, "Aluminum-Beryllium Alloy, Extrusions."

  11. 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.

  12. 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.

  13. 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.

  14. Laser beam welding of 5182 aluminum alloys sheet.

    SciTech Connect

    Leong, K. H.; Sabo, K. R.; Altshuller, B.; Wilkinson, T. L.; Albright, C. E.; Technology Development; Alcan International Limited; Reynolds Metals Co.; Ohio State Univ.

    1999-06-01

    Conditions were determined for consistent coupling of a CO{sub 2} laser beam to weld 5182 aluminum alloy sheet. Full penetration butt and bead-on-plate welds on 0.8 and 1.8 mm sheets were performed. Process conditions examined included beam mode, spot size and irradiance, shielding gas flow, and edge quality and fitup. The observed weld quality variations with the different process parameters were consistent with physical phenomena and a threshold irradiance model. Optimal conditions were determined for obtaining consistent welds on 5182 alloy sheets. Formability and tensile tests were performed on the welded samples. All test failures occurred in the fusion zone. Reduction in formability and tensile strength of the welded samples are discussed with respect to weld profiles and process parameters.

  15. Corrosive wear behavior of 2014 and 6061 aluminum alloy composites

    NASA Astrophysics Data System (ADS)

    Varma, S. K.; Andrews, S.; Vasquez, G.

    1999-02-01

    Alloys of 2014 and 6061 aluminum reinforced with 0.1 volume fraction of alumina particles (VFAP) were subjected to impact scratching during a corrosive wear process. The transient currents generated due to the impact were measured in the two composites as well as in their respective monoliths. The effect of solutionizing time on the transient currents was correlated to the near surface microstructures, scratch morphology, concentration of quenched-in vacancies, and changes in grain sizes. It was observed that the transient current values increase with an increase in solutionizing time, indicating that the corrosive wear behavior is not strongly affected by the grain boundaries. However, a combination of pitting and the galvanic corrosion may account for the typical corrosive wear behavior exhibited by the alloys and the composites of this study.

  16. 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)

  17. The Corrosion Protection of Metals by Ion Vapor Deposited Aluminum

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1993-01-01

    A study of the corrosion protection of substrate metals by ion vapor deposited aluminum (IVD Al) coats has been carried out. Corrosion protection by both anodized and unanodized IVD Al coats has been investigated. Base metals included in the study were 2219-T87 Al, 7075-T6 Al, Titanium-6 Al-4 Vanadium (Ti-6Al-4V), 4130 steel, D6AC steel, and 4340 steel. Results reveal that the anodized IVD Al coats provide excellent corrosion protection, but good protection is also achieved by IVD Al coats that have not been anodized.

  18. The corrosion protection of metals by ion vapor deposited aluminum

    SciTech Connect

    Danford, M.D.

    1993-10-01

    A study of the corrosion protection of substrate metals by ion vapor deposited aluminum (IVD Al) coats has been carried out. Corrosion protection by both anodized and unanodized IVD Al coats has been investigated. Base metals included in the study were 2219-T87 Al, 7075-T6 Al, Titanium-6 Al-4 Vanadium (Ti-6Al-4V), 4130 steel, D6AC steel, and 4340 steel. Results reveal that the anodized IVD Al coats provide excellent corrosion protection, but good protection is also achieved by IVD Al coats that have not been anodized.

  19. Interface Effects of the Properties and Processing of Graded Composite Aluminum Alloys

    DTIC Science & Technology

    2015-08-31

    Final Report: Interface effects of the properties and processing of graded composite aluminum alloys Report Title The objective of this STIR program...architecturally graded aluminum composite with a diffuse interface between alloys 5456 and 7055. The program supported the education and training of one graduate...2015 Approved for Public Release; Distribution Unlimited Final Report: Interface effects of the properties and processing of graded composite aluminum

  20. Computational Investigation of Hardness Evolution During Friction-Stir Welding of AA5083 and AA2139 Aluminum Alloys

    DTIC Science & Technology

    2011-01-01

    is combined with the basic physical metallurgy of two wrought aluminum alloys to predict/assess their FSW behaviors. The two alloys selected are AA5083... Aluminum Alloys Report Title ABSTRACT A fully coupled thermo-mechanical finite-element analysis of the friction-stir welding ( FSW ) process developed in our...previous work is combined with the basic physical metallurgy of two wrought aluminum alloys to predict/assess their FSW behaviors. The two alloys

  1. Corrosion resistance of sodium sulfate coated cobalt-chromium-aluminum alloys at 900 C, 1000 C, and 1100 C

    NASA Technical Reports Server (NTRS)

    Santoro, G. J.

    1979-01-01

    The corrosion of sodium sulfate coated cobalt alloys was measured and the results compared to the cyclic oxidation of alloys with the same composition, and to the hot corrosion of compositionally equivalent nickel-base alloys. Cobalt alloys with sufficient aluminum content to form aluminum containing scales corrode less than their nickel-base counterparts. The cobalt alloys with lower aluminum levels form CoO scales and corrode more than their nickel-base counterparts which form NiO scales.

  2. Development and Processing Improvement of Aerospace Aluminum Alloys-Development of AL-Cu-Mg-Ag Alloy (2139)

    NASA Technical Reports Server (NTRS)

    Cho, Alex; Lisagor, W. Barry; Bales, Thomas T.

    2007-01-01

    This final report supplement in presentation format describes a comprehensive multi-tasked contract study to continue the development of the silver bearing alloy now registered as aluminum alloy 2139 by the Aluminum Association. Two commercial scale ingots were processed into nominal plate gauges of two, four and six inches, and were extensively characterized in terms of metallurgical and crystallographic structure, and resulting mechanical properties. This report includes comparisons of the property combinations for this alloy and 2XXX and 7XXX alloys more widely used in high performance applications. Alloy 2139 shows dramatic improvement in all combinations of properties, moreover, the properties of this alloy are retained in all gauge thicknesses, contrary to typical reductions observed in thicker gauges of the other alloys in the comparison. The advancements achieved in this study are expected to result in rapid, widespread use of this alloy in a broad range of ground based, aircraft, and spacecraft applications.

  3. Fatigue crack growth in an aluminum alloy-fractographic study

    NASA Astrophysics Data System (ADS)

    Salam, I.; Muhammad, W.; Ejaz, N.

    2016-08-01

    A two-fold approach was adopted to understand the fatigue crack growth process in an Aluminum alloy; fatigue crack growth test of samples and analysis of fractured surfaces. Fatigue crack growth tests were conducted on middle tension M(T) samples prepared from an Aluminum alloy cylinder. The tests were conducted under constant amplitude loading at R ratio 0.1. The stress applied was from 20,30 and 40 per cent of the yield stress of the material. The fatigue crack growth data was recorded. After fatigue testing, the samples were subjected to detailed scanning electron microscopic (SEM) analysis. The resulting fracture surfaces were subjected to qualitative and quantitative fractographic examinations. Quantitative fracture analysis included an estimation of crack growth rate (CGR) in different regions. The effect of the microstructural features on fatigue crack growth was examined. It was observed that in stage II (crack growth region), the failure mode changes from intergranular to transgranular as the stress level increases. In the region of intergranular failure the localized brittle failure was observed and fatigue striations are difficult to reveal. However, in the region of transgranular failure the crack path is independent of the microstructural features. In this region, localized ductile failure mode was observed and well defined fatigue striations were present in the wake of fatigue crack. The effect of interaction of growing fatigue crack with microstructural features was not substantial. The final fracture (stage III) was ductile in all the cases.

  4. 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.

  5. 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.

  6. Fatigue Resistance of Liquid-assisted Self-repairing Aluminum Alloys Reinforced with Shape Memory Alloys

    NASA Technical Reports Server (NTRS)

    Wright, M. Clara; Manuel, Michele; Wallace, Terryl

    2013-01-01

    A self-repairing aluminum-based composite system has been developed using a liquid-assisted healing theory in conjunction with the shape memory effect of wire reinforcements. The metal-metal composite was thermodynamically designed to have a matrix with a relatively even dispersion of a low-melting eutectic phase, allowing for repair of cracks at a predetermined temperature. Additionally, shape memory alloy (SMA) wire reinforcements were used within the composite to provide crack closure. Investigators focused the research on fatigue cracks propagating through the matrix in order to show a proof-of-concept Shape Memory Alloy Self-Healing (SMASH) technology for aeronautical applications.

  7. 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.

  8. 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.

  9. Characterization of tribological behaviour of graphitic aluminum matrix composites, grey cast iron, and aluminum silicon alloys

    NASA Astrophysics Data System (ADS)

    Riahi, Ahmad Reza

    In recent years a number of aluminum-silicon alloys and some graphitic aluminum matrix composites have been fabricated for potential tribological applications in the automotive industry, in particular for lightweight high efficiency internal combustion engines to replace conventional uses of cast iron. This study provides a systematic investigation for wear mechanisms in dry sliding of the graphitic aluminum-matrix composites (A356 Al-10%SiC-4%Gr and A356 Al-5%Al2O3-3%Gr) developed for cylinder liner applications. Two eutectic Al-Si alloys (modified with rare earth elements) developed for wear resistant engine blocks were also studied. The tribological behavior of grey cast iron (ASTM A30), which is a traditional material for engine components, was also investigated as reference. For graphitic aluminum matrix composites, a wear mapping approach has been adopted. Three main regimes: ultra mild, mild and severe wear regions were determined in the maps; additionally, a scuffing region was observed. In the ultra mild wear regime the wear resistance was primarily due to the hard particles supporting the load. It was shown that the onset of severe wear in graphitic composites occurred at considerably higher loads compared to A356 aluminum alloy and A356 Al-20% SiC composite. At the onset of severe wear, the surface temperatures and coefficient of friction of the graphitic composites was lower than that of A356 Al-20% SiC. At all testing conditions in the mild wear regime, a protective tribo-layer was formed, which by increasing the speed and load became more continuous, more compact, smoother, and harder. The tribo-layers were removed at the onset of severe wear. An experimental wear map of grey cast iron was constructed; it consisted of three wear regimes: ultra mild, mild and severe wear. In the ultra mild regime a compacted fine iron oxide powder formed on the contact. The onset of severe wear was started with local material transfer to the steel counterface, and

  10. Method to increase the toughness of aluminum-lithium alloys at cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Sankaran, Krishnan K. (Inventor); Sova, Brian J. (Inventor); Babel, Henry W. (Inventor)

    2006-01-01

    A method to increase the toughness of the aluminum-lithium alloy C458 and similar alloys at cryogenic temperatures above their room temperature toughness is provided. Increasing the cryogenic toughness of the aluminum-lithium alloy C458 allows the use of alloy C458 for cryogenic tanks, for example for launch vehicles in the aerospace industry. A two-step aging treatment for alloy C458 is provided. A specific set of times and temperatures to age the aluminum-lithium alloy C458 to T8 temper is disclosed that results in a higher toughness at cryogenic temperatures compared to room temperature. The disclosed two-step aging treatment for alloy 458 can be easily practiced in the manufacturing process, does not involve impractical heating rates or durations, and does not degrade other material properties.

  11. Modeling the Controlled Recrystallization of Particle-Containing Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Adam, Khaled; Root, Jameson M.; Long, Zhengdong; Field, David P.

    2017-01-01

    The recrystallized fraction for AA7050 during the solution heat treatment is highly dependent upon the history of deformation during thermomechanical processing. In this work, a state variable model was developed to predict the recrystallization volume fraction as a function of processing parameters. Particle stimulated nucleation (PSN) was observed as a dominant mechanism of recrystallization in AA7050. The mesoscale Monte Carlo Potts model was used to simulate the evolved microstructure during static recrystallization with the given recrystallization fraction determined already by the state variable model for AA7050 alloy. The spatial inhomogeneity of nucleation is obtained from the measurement of the actual second-phase particle distribution in the matrix identified using backscattered electron (BSE) imaging. The state variable model showed good fit with the experimental results, and the simulated microstructures were quantitatively comparable to the experimental results for the PSN recrystallized microstructure of 7050 aluminum alloy. It was also found that the volume fraction of recrystallization did not proceed as dictated by the Avrami equation in this alloy because of the presence of the growth inhibitors.

  12. 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.

  13. 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.

  14. Modeling the Controlled Recrystallization of Particle-Containing Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Adam, Khaled; Root, Jameson M.; Long, Zhengdong; Field, David P.

    2016-12-01

    The recrystallized fraction for AA7050 during the solution heat treatment is highly dependent upon the history of deformation during thermomechanical processing. In this work, a state variable model was developed to predict the recrystallization volume fraction as a function of processing parameters. Particle stimulated nucleation (PSN) was observed as a dominant mechanism of recrystallization in AA7050. The mesoscale Monte Carlo Potts model was used to simulate the evolved microstructure during static recrystallization with the given recrystallization fraction determined already by the state variable model for AA7050 alloy. The spatial inhomogeneity of nucleation is obtained from the measurement of the actual second-phase particle distribution in the matrix identified using backscattered electron (BSE) imaging. The state variable model showed good fit with the experimental results, and the simulated microstructures were quantitatively comparable to the experimental results for the PSN recrystallized microstructure of 7050 aluminum alloy. It was also found that the volume fraction of recrystallization did not proceed as dictated by the Avrami equation in this alloy because of the presence of the growth inhibitors.

  15. Upgrading scrap automotive aluminum alloys with the impulse atomization and quench technique

    SciTech Connect

    Olsen, K.; Sterzik, G.; Henein, H.

    1995-12-31

    As aluminum alloy usage in automobiles grows, there are increasing demands on recycling processes and facilities to deal with mixed alloy automotive aluminum scrap. These processes and facilities strive to produce near virgin aluminum stock, which can be relatively costly and difficult. One alternative is to use physical processing methods to upgrade the scrap properties instead of chemically refining the scrap. The Impulse Atomization Process (IAP, patent pending) is a new process for making metallic and ceramic powders. It can produce fine homogeneous microstructures in scrap aluminum alloys due to high undercooling and rapid solidification. The particles have a very narrow size distribution and are in a convenient form for consolidation. This paper compares and contrasts the microstructural features of Impulse Atomized and quenched Impulse Atomized powders, for both AL6061 and a scrap aluminum alloy composition.

  16. High-strength laser welding of aluminum-lithium scandium-doped alloys

    NASA Astrophysics Data System (ADS)

    Malikov, A. G.; Ivanova, M. Yu.

    2016-11-01

    The work presents the experimental investigation of laser welding of an aluminum alloy (system Al-Mg-Li) and aluminum alloy (system Al-Cu-Li) doped with Sc. The influence of nano-structuring of the surface layer welded joint by cold plastic deformation on the strength properties of the welded joint is determined. It is founded that, regarding the deformation degree over the thickness, the varying value of the welded joint strength is different for these aluminum alloys. The strength of the plastically deformed welded joint, aluminum alloys of the Al-Mg-Li and Al-Cu-Li systems reached 0.95 and 0.6 of the base alloy strength, respectively.

  17. Fracture characteristics of structural aerospace alloys containing deep surface flaws. [aluminum-titanium alloys

    NASA Technical Reports Server (NTRS)

    Masters, J. N.; Bixler, W. D.; Finger, R. W.

    1973-01-01

    Conditions controlling the growth and fracture of deep surface flaws in aerospace alloys were investigated. Static fracture tests were performed on 7075-T651 and 2219-T87 aluminum, and 6Ai-4V STA titanium . Cyclic flaw growth tests were performed on the two latter alloys, and sustain load tests were performed on the titanium alloy. Both the cyclic and the sustain load tests were performed with and without a prior proof overload cycle to investigate possible growth retardation effects. Variables included in all test series were thickness, flaw depth-to-thickness ratio, and flaw shape. Results were analyzed and compared with previously developed data to determine the limits of applicability of available modified linear elastic fracture solutions.

  18. Tribological characteristics of aluminum alloys against steel lubricated by ammonium and imidazolium ionic liquids

    SciTech Connect

    Qu, Jun; Blau, Peter Julian; Dai, Sheng; Luo, Huimin; Meyer III, Harry M; Truhan, John J.

    2009-01-01

    Sliding friction and wear characteristics of aluminum alloys against AISI 52100 steel lubricated by ionic liquids (ILs) were investigated at both room and elevated temperatures. The tested aluminum alloys include a commercially pure aluminum Al 1100, a wrought alloy Al 6061-T6511, and a cast alloy Al 319-T6. The lubricating performance of two ILs with the same anion, one ammonium-based [C8H17]3NH.Tf2N and one imidazolium-based C10mim.Tf2N, were compared each other and benchmarked against that of a conventional fully-formulated engine oil. Significant friction (up to 35%) and wear (up to 55%) reductions were achieved by the ammonium IL when lubricating the three aluminum alloys compared to the engine oil. The imidazolium IL performed better than the oil but not as well as the ammonium IL for Al 1100 and 319 alloys. However, accelerated wear was unexpectedly observed for Al 6061 alloy when lubricated by C10mim.Tf2N. Surface chemical analyses implied complex tribochemical reactions between the aluminum surfaces and ILs during the wear testing, which has been demonstrated either beneficial by forming a protective boundary film or detrimental by causing severe tribo-corrosion. The effects of the IL cation structure, aluminum alloy composition, and tribo-testing condition on the friction and wear results have been discussed.

  19. Deformation behavior of aluminum alloy 6111-T4

    NASA Astrophysics Data System (ADS)

    Tseng, Carol

    2000-10-01

    Although aluminum alloys have found increasing usage in the automotive industry, their lower tensile elongations as compared with the low carbon steels they replace has raised concern about their lower formability. Lower formability imposes design and economic constraints on the automakers. The cause behind this lower elongation is the primary focus of this research. The specific alloy studied is 6111-T4 (Al-0.76Si-0.61Mg-0.82Cu in w/o), which is used in automobile outer body panels. In order to determine the factors that are limiting the elongation, it is critical to understand the deformation behavior of this alloy. To investigate the deformation behavior of this alloy, uniaxial tensile tests were performed at various temperatures (300K, 77K and 4.2K), strain rates (10-4, 5 x 10-4 , 10-3, 10-2, 10 -1/s) and specimen geometries. The work hardening and deformation behavior were examined both qualitatively and quantitatively. Ex-situ and in-situ observations were made on the tensile samples by using videography and optical microscopy. Several important findings resulted from this study. First, oscillations in the work hardening are due to the formation and propagation of deformation islands and deformation bands. Deformation islands are areas of localized deformation that occur in a cluster of grains. Second, the microstructural feature dominating the formation and propagation of the islands are the clustering of similarly oriented grains and the clustering of large sized grains. Third, the sharp drop in work hardening near the diffuse necking criterion for the 300K, 10-4 is test samples is due to the inhomogeneous deformation arising from these clusters. Finally, diffuse and local necks form before the theoretical predictions. The inhomogeneous microstructures causing the deformation islands and bands to form and propagate, thus leading to strain localization and eventual premature failure.

  20. 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.

  1. Properties of welded joints in laser welding of aeronautic aluminum-lithium alloys

    NASA Astrophysics Data System (ADS)

    Malikov, A. G.; Orishich, A. M.

    2017-01-01

    The work presents the experimental investigation of the laser welding of the aluminum-lithium alloys (system Al-Mg-Li) and aluminum alloy (system Al-Cu-Li) doped with Sc. The influence of the nano-structuring of the surface layer welded joint by the cold plastic deformation method on the strength properties of the welded joint is determined. It is founded that, regarding the deformation degree over the thickness, the varying value of the welded joint strength is different for these aluminum alloys.

  2. The hydrogen diffusion in liquid aluminum alloys from ab initio molecular dynamics

    NASA Astrophysics Data System (ADS)

    Jakse, N.; Pasturel, A.

    2014-09-01

    We study the hydrogen diffusion in liquid aluminum alloys through extensive ab initio molecular dynamics simulations. At the microscopic scale, we show that the hydrogen motion is characterized by a broad distribution of spatial jumps that does not correspond to a Brownian motion. To determine the self-diffusion coefficient of hydrogen in liquid aluminum alloys, we use a generalized continuous time random walk model recently developed to describe the hydrogen diffusion in pure aluminum. In particular, we show that the model successfully accounts the effects of alloying elements on the hydrogen diffusion in agreement with experimental features.

  3. 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

  4. Mechanisms of pressure filtration of liquid aluminum alloys

    NASA Astrophysics Data System (ADS)

    Cao, X.

    2006-12-01

    The Prefil Footprinter, a portable pressure filtration instrument, is usually used to detect the quality of liquid aluminum alloys. However, no investigations have ever been done to calculate the cake resistance to date. Based on the identification and classification of flow behavior using the first derivative method for filtrate mass vs filtration time curves, conventional filtration equations are successfully employed to understand the filtration behaviors. From the analyses of the variations of cake resistance with filtration time, the filtration mechanisms are discussed in detail over the different filtration stages. During the steady stage, either incompressible or compressible cake mode is the main mechanism. At the initial and terminal transient stages, however, deep-bed filtration, complete straining, and solidification clogging may appear. Solid inclusions in liquid metal have significant influence on the cake structures and properties. Some important issues related to the heterogeneity of filter media and test methodology are highlighted in this work.

  5. Laser Surface Alloying of Copper, Manganese, and Magnesium with Pure Aluminum Substrate

    NASA Astrophysics Data System (ADS)

    Jiru, Woldetinsay G.; Sankar, M. Ravi; Dixit, Uday S.

    2016-03-01

    Laser surface alloying is one of the recent technologies used in the manufacturing sector for improving the surface properties of the metals. Light weight materials like aluminum alloys, titanium alloys, and magnesium alloys are used in the locomotive, aerospace, and structural applications. In the present work, an experimental study was conducted to improve the surface hardness of commercially pure aluminum plate. CO2 laser is used to melt pre-placed powders of pure copper, manganese, and magnesium. Microstructure of alloyed surface was analyzed using optical microscope. The best surface alloying was obtained at the optimum values of laser parameters, viz., laser power, scan speed, and laser beam diameter. In the alloyed region, microhardness increased from 30 HV0.5 to 430 HV0.5, while it was 60 HV0.5 in the heat-affected region. Tensile tests revealed some reduction in the strength and total elongation due to alloying. On the other hand, corrosion resistance improved.

  6. Formability analysis of aluminum alloys through deep drawing process

    NASA Astrophysics Data System (ADS)

    Pranavi, U.; Janaki Ramulu, Perumalla; Chandramouli, Ch; Govardhan, Dasari; Prasad, PVS. Ram

    2016-09-01

    Deep drawing process is a significant metal forming process used in the sheet metal forming operations. From this process complex shapes can be manufactured with fewer defects. Deep drawing process has different effectible process parameters from which an optimum level of parameters should be identified so that an efficient final product with required mechanical properties will be obtained. The present work is to evaluate the formability of Aluminum alloy sheets using deep drawing process. In which effects of punch radius, lubricating conditions, die radius, and blank holding forces on deep drawing process observed for AA 6061 aluminum alloy sheet of 2 mm thickness. The numerical simulations are performed for deep drawing of square cups using three levels of aforesaid parameters like lubricating conditions and blank holding forces and two levels of punch radii and die radii. For numerical simulation a commercial FEM code is used in which Hollomon's power law and Hill's 1948 yield criterions are implemented. The deep drawing setup used in the FEM code is modeled using a CAD tool by considering the modeling requirements from the literature. Two different strain paths (150x150mm and 200x200mm) are simulated. Punch forces, thickness distributions and dome heights are evaluated for all the conditions. In addition failure initiation and propagation is also observed. From the results, by increasing the coefficient of friction and blank holding force, punch force, thickness distribution and dome height variations are observed. The comparison has done and the optimistic parameters were suggested from the results. From this work one can predict the formability for different strain paths without experimentation.

  7. Factors Influencing Fracture Toughness and Other Properties of Aluminum- Lithium Alloys

    DTIC Science & Technology

    1979-06-14

    tramp elements sodium, potassium and sulfuir presumably segregated in the grain boundaries. Furthermore, the hydrogen content of the alloys was also shown...tion of these elements at grain boundaries is worth noting. Furthermore, the hydrogen content of the Al-Li and A1-Mg-Li alloys is significantly higher...than the hydrogen content of typical commerical high strength aluminum alloys. Fatigue Crack Growth (FCG) The FCG performance of the Al-Cu-Li alloy

  8. Laser-initiated combustion studies of selected aluminum, copper, iron, and nickel alloys

    NASA Technical Reports Server (NTRS)

    Bransford, J. W.; Clark, A. F.

    1981-01-01

    The results of combustion studies at atmospheric pressure on ten metal alloys are presented. The alloys studied were aluminum alloys 1100, 2219, 6061, and tensile-50; 304, 347 and 21-6-9 stainless steel; inconel 600; beryllium copper and a bronze. It was found that once ignition was achieved all alloys would generally burn to completion. The overall combustion process appears to obey a first order rate process. Preliminary conclusions are presented along with recommendations for future work.

  9. Long-term strategies for increased recycling of automotive aluminum and its alloying elements.

    PubMed

    Løvik, Amund N; Modaresi, Roja; Müller, Daniel B

    2014-04-15

    Aluminum recycling currently occurs in a cascading fashion, where some alloys, used in a limited number of applications, absorb most of the end-of-life scrap. An expected increase in scrap supply in coming decades necessitates restructuring of the aluminum cycle to open up new recycling paths for alloys and avoid a potential scrap surplus. This paper explores various interventions in end-of-life management and recycling of automotive aluminum, using a dynamic substance flow analysis model of aluminum and its alloying elements with resolution on component and alloy level (vehicle-component-alloy-element model). It was found that increased component dismantling before vehicle shredding can be an effective, so far underestimated, intervention in the medium term, especially if combined with development of safety-relevant components such as wheels from secondary material. In the long term, automatic alloy sorting technologies are most likely required, but could at the same time reduce the need for magnesium removal in refining. Cooperation between the primary and secondary aluminum industries, the automotive industry, and end-of-life vehicle dismantlers is therefore essential to ensure continued recycling of automotive aluminum and its alloying elements.

  10. Fretting of Nickel-Chromium-Aluminum Alloys at Temperatures to 816 C

    NASA Technical Reports Server (NTRS)

    Bill, R. C.

    1974-01-01

    A series of four nickel-based alloys containing 10 percent and 20 percent chromium in combination with 2 percent and 5 percent aluminum were fretted in dry air at temperatures to 816 C. At all temperatures, the alloys showed far less fretting wear than did high-purity nickel. This was attributed to the formation of protective oxide films on the alloys, the result of the selective oxidation of the alloy constituents. Increasing the aluminum concentration reduced fretting wear at all temperatures. Increasing the chromium concentration from 10 percent to 20 percent resulted in decreased fretting wear at 23 and 540 C, but increased fretting wear at 650 and 816 C.

  11. 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.

  12. 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.

  13. Microstructure of aluminum-iron alloys subjected to severe plastic deformation

    SciTech Connect

    Senkov, O.N.; Froes, F.H.; Stolyarov, V.V.; Valiev, R.Z.; Liu, J.

    1998-04-14

    The present paper describes detailed experiments on structure and phase characterization carried out on aluminum-iron alloys after intense torsion straining. The equilibrium solubility of iron in the aluminum lattice at room temperature has been reported to be 0.025 at.%. Alloying of aluminum with iron can increase the high-temperature strength due to a dispersion of second-phase particles. This effect can be enhanced by increasing the solid solubility extension of iron in the aluminum matrix and producing non-equilibrium phases by techniques such as RS, MA or even a laser treatment. In the present work, the severe plastic deformation approach has been used to extend the iron solubility in aluminum and to produce a nano-grained structure in several Al-Fe alloys.

  14. Minimum quantity lubrication machining of aluminum and magnesium alloys

    NASA Astrophysics Data System (ADS)

    Bhowmick, Sukanta

    2011-12-01

    The use of minimum quantity lubrication (MQL) machining, i.e. drilling and tapping of aluminum and magnesium alloys using very low quantities of cutting fluids was studied and the MQL machining performance was compared to dry and conventional flooded conditions. An experimental drilling station with an MQL system was built to measure torque and thrust force responses. Uncoated and diamond-like carbon (DLC) coated HSS drills were tested against 319 Al and AZ91 alloys using 10--50 ml/h of distilled water (H 2O-MQL) and a fatty acid based MQL agent (FA-MQL). The results indicated that H2O-MQL used in conjunction with non-hydrogenated DLC (NH-DLC) coatings reduced the average torque and thrust-force compared to dry cutting and achieved a performance comparable with conventional flooded drilling. At least 103 holes could be drilled using NH-DLC in H2O-MQL and uncoated HSS in FA-MQL in drilling of both 319 Al and AZ91. MQL drilling and tapping provided a stable machining performance, which was evident from the uniform torque and force patterns and also resulted in desirable hole surface, thread quality and chip segments. The maximum temperature generated in the workpiece during MQL machining was lower than that observed in dry drilling and tapping, and comparable to flooded conditions. The mechanical properties of the material adjacent to drilled holes, as evaluated through plastic strain and hardness measurements, revealed a notable softening in case of dry drilling, with magnesium alloys exhibiting a recrystallized grain zone, but not for MQL drilling. Softened aluminum and magnesium promoted adhesion to the tools resulted built-up edge formation and consequently high torques and thrust-forces were generated. NH-DLC coatings' low COF in H 2O-MQL against 319 Al (0.10) and AZ91 (0.12) compared to uncoated HSS (0.63 and 0.65) limited the temperature increase during NH-DLC in H2 O-MQL drilling and hence both torques and thrust forces were effectively reduced.

  15. 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.

  16. 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.

  17. Iron-niobium-aluminum alloy having high-temperature corrosion resistance

    DOEpatents

    Hsu, Huey S.

    1988-04-14

    An alloy for use in high temperature sulfur and oxygen containing environments, having aluminum for oxygen resistance, niobium for sulfur resistance and the balance iron, is discussed. 4 figs., 2 tabs.

  18. Cryogenic Fracture Toughness Evaluation of an Investment Cast Aluminum-Beryllium Alloy for Structural Applications

    NASA Technical Reports Server (NTRS)

    Gamwell, Wayne; McGill, Preston

    2006-01-01

    This document is a viewgraph presentation that details the fracture toughness of Aluminum-Beryllium Alloy for use in structures at cryogenic temperatures. Graphs and charts are presented in the presentation

  19. Study to determine peening stress profile of rod peened aluminum structural alloys versus shot peened material

    NASA Technical Reports Server (NTRS)

    Rosas, R. E.; Calfin, B. G.

    1976-01-01

    The objective of this program was to determine the peening stress profiles of rod peened aluminum structural alloys versus shot peened material to define the effective depth of the compressed surface layer.

  20. New water-soluble metal working fluids additives from phosphonic acid derivatives for aluminum alloy materials.

    PubMed

    Kohara, Ichitaro; Tomoda, Hideyuki; Watanabe, Shoji

    2007-01-01

    Water-soluble metal working fluids are used for processing of aluminum alloy materials. This short paper describes properties of new additives for water-soluble cutting fluids for aluminum alloy materials. Some alkyldiphosphonic acids were prepared with known method. Amine salts of these phosphonic acids showed anti-corrosion property for aluminum alloy materials. However, they have no hard water tolerance. Monoesters of octylphosphonic acid were prepared by the reaction of octylphosphonic acid dichloride with various alcohols in the presence of triethylamine. Amine salts of monoester of octylphosphonic acid with diethyleneglycol monomethyl ether, ethyleneglycol monomethyl ether and triethyleneglycol monomethyl ether showed both of a good anti-corrosion property for aluminum alloy materials and hard water tolerance.

  1. 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.

  2. Study of localized corrosion in aluminum alloys by the scanning reference electrode technique

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1995-01-01

    Localized corrosion in 2219-T87 aluminum (Al) alloy, 2195 aluminum-lithium (Al-Li) alloy, and welded 2195 Al-Li alloy (4043 filler) have been investigated using the relatively new scanning reference electrode technique (SRET). Anodic sites are more frequent and of greater strength in the 2195 Al-Li alloy than in the 2219-T87 Al alloy, indicating a greater tendency toward pitting for the latter. However, the overall corrosion rates are about the same for these two alloys, as determined using the polarization resistance technique. In the welded 2195 Al-Li alloy, the weld bean is entirely cathodic, with rather strongly anodic heat affected zones (HAZ) bordering both sides, indicating a high probability of corrosion in the HAZ parallel to the weld bead.

  3. Fatigue Behavior of Long and Short Cracks in Wrought and Powder Aluminum Alloys.

    DTIC Science & Technology

    1986-05-01

    6 mm aluminum alloy 7075 and, unlike behavior in cycle -l) near the fatigue threshold stress in- steels (4-61, were not consistent with lower tensity...NO. ACCESSION NO. ____ _.-__’__ ____ ___ ____ ___ _ _ __2306 Al I 11. TITLE (Include Security Classification) FATIGUE BEHAVIOR OF LONG AND SHORT...amplitude loading; Fatigue in aluminum alloys; Fatigue behavior of lon and short cracks; Fatigue cracks: crack closure . ABSTRACT (Continue on reverse if

  4. 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.

  5. 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.

  6. Laser fusing of HVOF thermal sprayed alloy 625 on nickel-aluminum bronze

    SciTech Connect

    Brenna, R.T.; Pugh, J.L.; Denney, P.E.

    1994-12-31

    A preliminary study has been conducted to determine the feasibility of laser fusing alloy 625 onto nickel-aluminum-bronze base metal. Laser fusing was performed by melting a pre-coated surface of alloy 625 that had been applied by the high velocity oxyfuel (HVOF) thermal spray process. The laser fusing was successful in producing a metallurigical bond between alloy 625 and the substrate. Minor modification to the heat-affected zone of the base metal was observed by microhardness measurements, and defect-free interfaces were produced between alloy 625 and nickel-aluminum-bronze by the process. The laser is a high energy density source that can be used for precise thermal processing of materials including surface modification. Laser fusing is the full or partial melting of a coating material that has been previously applied in some fashion to the substrate. Thermal spray coating of nickel-aluminum-bronze material with alloy 625 was conducted at the David Taylor Research Center. Nickel-aluminum-bronze specimens 2 x 3-in. by 1/2-in. thick were coated with alloy 25 utilizing the HVOF equipment. Coating thicknesses of approximately 0.014-in. (0.3 mm) were produced for subsequent laser fusing experiments. A preliminary study has been conducted to determine the feasibility of laser fusing a HVOF thermal sprayed alloy 625 coating onto nickel-aluminum-bronze base metal. Conclusions of this investigation were as follows: (1) Laser fusing was successful in producing a metallurgical bond between HVOF thermal sprayed alloy 625 and the nickel-aluminum-bronze. (2) Only minor microstructural modification to the heat-affected zone of the base metal ws observed by microhardness measurements. (3) Defect-free interfaces were produced between thermal sprayed alloy 625 and nickel-aluminum-bronze by laser fusing.

  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. Oxidation resistance of aluminum-coated Fe-20Cr alloys containing rare earths or yttrium

    SciTech Connect

    Sigler, D.R. )

    1993-10-01

    Aluminum-coated Fe-20Cr (rare earth or yttrium) alloy foils were developed with oxidation resistance equivalent or superior to Fe-20Cr-5Al (rare earth or yttrium) alloy foils. The coated foils were made by dipping Fe-20Cr sheet into a salt-covered aluminum bath and then rolling the sheet to foil. Oxidation resistance of the coated foil was enhanced by adding rare earths or yttrium to the Fe-20Cr substrate alloys to insure oxide adherence. Test results indicate that only sufficient addition to tie up sulfur as a stable sulfide is needed in the Fe-20Cr alloy. Aluminum-coated foils show lower oxide growth rates than similar Fe-Cr-Al alloys, most likely the result of fewer impurities (particularly Fe) is the coated foils' growing oxide scale. 31 refs., 18 figs., 2 tabs.

  9. Brazing process using'al-Si filler alloy reliably bonds aluminum parts

    NASA Technical Reports Server (NTRS)

    Beuyukian, C. S.; Johnson, W. R.

    1966-01-01

    Brazing process employs an aluminum-silicon filler alloy for diffusion bonding of aluminum parts in a vacuum or inert gas atmosphere. This process is carried out at temperatures substantially below those required in conventional process and produces bonds of greater strength and reliability.

  10. 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.

  11. Hot stamping of AA7075 aluminum sheets

    NASA Astrophysics Data System (ADS)

    Mendiguren, J.; Saenz de Argandona, E.; Galdos, L.

    2016-11-01

    In this work the formability of a high strength aluminium alloy (AA7075-T6) for the stamping of an automotive component has been studied. Due to the low formability of the selected alloy, two different heat assisted forming strategies have been analysed. On the one hand, the W-temper process, where the thermal process is carried out prior to the forming operation. On the other hand, the hot stamping process, where the thermal process is carried out at the same time as the forming. The results showed that both technology were able to form the component avoiding any failure of the material. On the contrary, both processes reduced the final mechanical properties of the material compared to the as received material condition. However, the obtained mechanical properties doubled the strength of commonly used 5xxx and 6xxx aluminium alloys.

  12. Magnesium Rich Primer for Chrome Free Protection of Aluminum Alloys (Preprint)

    DTIC Science & Technology

    2007-12-01

    the solubility of aluminum oxide and its hydrates (FIGURE 4), one can’t help but wonder if the ability to maintain a local pH near neutrality is an...FIGURE 4 – Solubility of aluminum oxide and its hydrates as a function of pH.8 7 QUALIFICATION AND TRANSITION PLAN The preliminary results...AFRL-RX-WP-TP-2008-4012 MAGNESIUM RICH PRIMER FOR CHROME FREE PROTECTION OF ALUMINUM ALLOYS (Preprint) Joel A. Johnson Nonstructural

  13. Wear of aluminum and hypoeutectic aluminum-silicon alloys in boundary-lubricated pin-on disk sliding

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Brainard, W. A.

    1979-01-01

    The friction and wear of pure aluminum and a number of hypoeutectic aluminum-silicon alloys (with 3 to 12 wt %Si) were studied with a pin-on-disk apparatus. The contacts were lubricated with mineral oil and sliding was in the boundary-lubrication regime at 2.6 cm/sec. Surfaces were analyzed with photomicrographs, scanning electron microscopy, X-ray dispersive analysis, and diamond pyramid hardness measurements. There were two wear regimes for the alloys - high and low - whereas pure aluminum exhibited a high wear rate throughout the test period. Wear rate decreased and the transition stress from high to low wear increased with increasing hardness. There was no correlation between friction coefficient and hardness. A least squares curve fit indicated a wear-rate dependence greater than the inverse first power of hardness. The lower wear rates of the alloys may be due to the composites of silicon platelets in aluminum resulting in increased hardness and thus impairing the shear of the aluminum.

  14. Corrosion resistance of aluminum-magnesium alloys in glacial acetic acid

    SciTech Connect

    Zaitseva, L.V.; Romaniv, V.I.

    1984-05-01

    Vessels for the storage and conveyance of glacial acetic acid are produced from ADO and AD1 aluminum, which are distinguished by corrosion resistance, weldability and workability in the hot and cold conditions but have low tensile strength. Aluminum-magnesium alloys are stronger materials close in corrosion resistance to technical purity aluminum. An investigation was made of the basic alloying components on the corrosion resistance of these alloys in glacial acetic acid. Both the base metal and the weld joints were tested. With an increase in temperature the corrosion rate of all of the tested materials increases by tens of times. The metals with higher magnesium content show more pitting damage. The relationship of the corrosion resistance of the alloys to magnesium content is confirmed by the similar intensity of failure of the joint metal of all of the investigated alloys and by electrochemical investigations. The data shows that AMg3 alloy is close to technically pure ADO aluminum. However, the susceptibility of even this material to local corrosion eliminates the possibility of the use of aluminum-magnesium alloys as reliable constructional materials in glacial acetic acid.

  15. 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.

  16. 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

  17. Ultrafine nanoporous palladium-aluminum film fabricated by citric acid-assisted hot-water-treatment of aluminum-palladium alloy film

    SciTech Connect

    Harumoto, Takashi; Tamura, Yohei; Ishiguro, Takashi

    2015-01-15

    Hot-water-treatment has been adapted to fabricate ultrafine nanoporous palladium-aluminum film from aluminum-palladium alloy film. Using citric acid as a chelating agent, a precipitation of boehmite (aluminum oxide hydroxide, AlOOH) on the nanoporous palladium-aluminum film was suppressed. According to cross-sectional scanning transmission electron microscopy observations, the ligament/pore sizes of the prepared nanoporous film were considerably small (on the order of 10 nm). Since this fabrication method only requires aluminum alloy film and hot-water with chelating agent, the ultrafine nanoporous film can be prepared simply and environmentally friendly.

  18. Aging Optimization of Aluminum-Lithium Alloy C458 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H. W.; Farahmand, B.; Rioja, R.

    2003-01-01

    This viewgraph report presents an examination of the fracture toughness of aluminum-lithium alloy C458 for use in cryotank structures. Topics cover include: cryogenics, alloy composition, strengthing precipitates in C458, cryogenic fracture toughness improvements, design of experiments for measuring aging optimization of C458 plate and effects of aging of properties of C458 plate.

  19. Exploratory Development for Design Data on Structural Aluminum Alloys in Representative Aircraft Environments

    DTIC Science & Technology

    1977-07-01

    Alloy," Final Report under Naval Air Systems Command Contract N00019-69- C-0292, January 1970. 6. D. J. Brownhill, C. F. Babilon , G. E. Nordmark and D. 0...34Further Development of Aluminum Alloy X7050," Final Report under Naval Air Systems Command Contract N00019- 71-C-0131, May 1972. 9. C. F. Babilon , R

  20. 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.

  1. 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.

  2. 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.

  3. Study of Magnetic Alloys: Critical Phenomena.

    DTIC Science & Technology

    MAGNETIC ALLOYS, TRANSPORT PROPERTIES), ELECTRICAL RESISTANCE, SEEBECK EFFECT , MAGNETIC PROPERTIES, ALUMINUM ALLOYS, COBALT ALLOYS, GADOLINIUM ALLOYS, GOLD ALLOYS, IRON ALLOYS, NICKEL ALLOYS, PALLADIUM ALLOYS, PLATINUM ALLOYS, RHODIUM ALLOYS

  4. 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%.

  5. 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.

  6. Several braze filler metals for joining an oxide-dispersion-strengthened nickel-chromium-aluminum alloy

    NASA Technical Reports Server (NTRS)

    Gyorgak, C. A.

    1975-01-01

    An evaluation was made of five braze filler metals for joining an aluminum-containing oxide dispersion-strengthened (ODS) alloy, TD-NiCrAl. All five braze filler metals evaluated are considered suitable for joining TD-NiCrAl in terms of wettability and flow. Also, the braze alloys appear to be tolerant of slight variations in brazing procedures since joints prepared by three sources using three of the braze filler metals exhibited similar brazing characteristics and essentially equivalent 1100 C stress-rupture properties in a brazed butt-joint configuration. Recommendations are provided for brazing the aluminum-containing ODS alloys.

  7. Electrochemical test for predicting microbiologically influenced corrosion of aluminum and AA 7005 alloy

    SciTech Connect

    Ayllon, E.S. ); Rosales, B.M. )

    1994-08-01

    The susceptibility of pure aluminum (Al) and Aluminum Association (AA) 7005 alloy (UNS A97005) to pitting by microbiologically influenced corrosion (MIC) in an integral jet fuel tank was determined through polarization measurements. Usually, the most corrosive reported species is the fungus Hormonconis resinae. The effect of its proliferation on pure Al and AA 7005-T6 alloy was studied through anodic and cathodic potentiodynamic polarization. The type and relative amount of corrosion damage to the metal were determined. Morphology of the attack was analyzed by scanning electron microscopy (SEM). Distribution of the alloying elements was determined using energy dispersive x-ray analysis (EDXA).

  8. 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.

  9. Chemical conditions inside occluded regions on corroding aircraft aluminum alloys.

    PubMed

    Lewis, K S; Yuan, J; Kelly, R G

    1999-07-30

    Corrosion of aluminum alloy structures costs the US Air Force in the order of US$1 x 10(9) annually. Corrosion develops in areas of overlap such as aircraft lap-splice joints and under protective organic coatings. Capillary electrophoresis (CE) has been used to determine the local chemistries at these corrosion sites of solutions that were extracted using a microsampling system. Analysis of the local solution within lap-splice joints from aircraft has been performed in two ways: rehydration of corrosion products and direct microsampling. The solutions collected were analyzed with CE to quantitatively determine the species present during corrosion. The most common ions detected were Cl-, NO2-, NO3-, HCO3-, K+, Al3+, Ca2+, Na+ and Mg2+. Studies of the solution chemistry under local coating defects are required to understand coating failure and develop more durable coatings. A microsampling system and micro pH sensor were developed to extract solution from and measure pH in defects with diameters as small as 170 microns. Actively corroding defects contained high concentrations of Cl-, Al3+, Mg2+, Mn2+ and Cu2+ whereas only trace levels of Mg2+ were found in repassivated defects. The effects of these species on initiation and propagation of corrosion are discussed.

  10. 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.

  11. 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.

  12. Nucleation Catalysis in Aluminum Alloy A356 Using Nanoscale Inoculants

    NASA Astrophysics Data System (ADS)

    de Cicco, Michael P.; Turng, Lih-Sheng; Li, Xiaochun; Perepezko, John H.

    2011-08-01

    Different types of nanoparticles in aluminum (Al) alloy A356 nanocomposites were shown to catalyze nucleation of the primary Al phase. Nanoparticles of SiC β, TiC, Al2O3 α, and Al2O3 γ were added to and dispersed in the A356 matrix as nucleation catalysts using an ultrasonic mixing technique. Using the droplet emulsion technique (DET), undercoolings in the nanocomposites were shown to be significantly reduced compared to the reference A356. None of the nanocomposites had a population of highly undercooled droplets that were observed in the reference samples. Also, with the exception of the A356/Al2O3 α nanocomposite, all nanocomposites showed a reduction in undercooling necessary for the onset of primary Al nucleation. The observed nanocomposite undercoolings generally agreed with the undercooling necessary for free growth. The atomic structure of the particles showed an influence on nucleation potency as A356/Al2O3 γ nanocomposites had smaller undercoolings than A356/Al2O3 α nanocomposites. The nucleation catalysis illustrates the feasibility of, and basis for, grain refinement in metal matrix nanocomposites (MMNCs).

  13. Ultrasonic measurement of residual stress in shot peened aluminum alloy

    NASA Astrophysics Data System (ADS)

    Lavrentyev, Anton I.; Veronesi, William A.

    2001-04-01

    Shot peening is a well-known method for extending the fatigue life of metal components by introducing compressive residual stresses near their surfaces. The capability to non-destructively evaluate the near surface residual stress would greatly aid the assurance of proper fatigue life in shot-peened components. This paper addresses issues encountered in near-surface residual stress measurement by an ultrasonic surface wave method. In this method, a variation of ultrasonic surface wave speed with shot peening intensity is measured. Since the effective wave penetration depth inversely related to the excitation frequency, by making measurements at different frequencies, the method has the potential to provide the stress-depth profile. Experiments were conducted on aluminum specimens (alloy 7075-T7351) peened within the Almen peening intensity from 4A-16A. Several factors were found to contribute to the measured responses: surface roughness, near surface texture change, dislocation density increase and residual stress. In this paper, the contributions of residual stress, dislocation density and surface roughness to the overall effect are separately estimated. It is shown that the experimentally observed velocity change in shot peened samples is dominated by the effect of surface roughness while the role of residual stress is much smaller.

  14. Adhesion enhancement of titanium nitride coating on aluminum casting alloy by intrinsic microstructures

    NASA Astrophysics Data System (ADS)

    Nguyen, Chuong L.; Preston, Andrew; Tran, Anh T. T.; Dickinson, Michelle; Metson, James B.

    2016-07-01

    Aluminum casting alloys have excellent castability, high strength and good corrosion resistance. However, the presence of silicon in these alloys prevents surface finishing with conventional methods such as anodizing. Hard coating with titanium nitride can provide wear and corrosion resistances, as well as the aesthetic finish. A critical factor for a durable hard coating is its bonding with the underlying substrate. In this study, a titanium nitride layer was coated on LM25 casting alloy and a reference high purity aluminum substrate using Ion Assisted Deposition. Characterization of the coating and the critical interface was carried out by a range of complementing techniques, including SIMS, XPS, TEM, SEM/EDS and nano-indentation. It was observed that the coating on the aluminum alloy is stronger compared to that on the pure aluminum counterpart. Silicon particles in the alloy offers the reinforcement though mechanical interlocking at microscopic level, even with nano-scale height difference. This reinforcement overcomes the adverse effect caused by surface segregation of magnesium in aluminum casting alloys.

  15. Carbothermic reduction and prereduced charge for producing aluminum-silicon alloys

    DOEpatents

    Stevenson, David T.; Troup, Robert L.

    1985-01-01

    Disclosed is a method for the carbothermic reduction of aluminum oxide to form an aluminum alloy including producing silicon carbide by heating a first mix of carbon and silicon oxide in a combustion reactor to an elevated temperature sufficient to produce silicon carbide at an accelerated rate, the heating being provided by an in situ combustion with oxygen gas, and then admixing the silicon carbide with carbon and aluminum oxide to form a second mix and heating the second mix in a second reactor to an elevated metal-forming temperature sufficient to produce aluminum-silicon alloy. The prereduction step includes holding aluminum oxide substantially absent from the combustion reactor. The metal-forming step includes feeding silicon oxide in a preferred ratio with silicon carbide.

  16. Carbothermic reduction and prereduced charge for producing aluminum-silicon alloys

    DOEpatents

    Stevenson, D.T.; Troup, R.L.

    1985-01-01

    Disclosed is a method for the carbothermic reduction of aluminum oxide to form an aluminum alloy including producing silicon carbide by heating a first mix of carbon and silicon oxide in a combustion reactor to an elevated temperature sufficient to produce silicon carbide at an accelerated rate, the heating being provided by an in situ combustion with oxygen gas, and then admixing the silicon carbide with carbon and aluminum oxide to form a second mix and heating the second mix in a second reactor to an elevated metal-forming temperature sufficient to produce aluminum-silicon alloy. The prereduction step includes holding aluminum oxide substantially absent from the combustion reactor. The metal-forming step includes feeding silicon oxide in a preferred ratio with silicon carbide. 1 fig.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Aluminum base alloy powder metallurgy process and product

    NASA Technical Reports Server (NTRS)

    Paris, Henry G. (Inventor)

    1986-01-01

    A metallurgical method including cooling molten aluminum particles and consolidating resulting solidified particles into a multiparticle body, wherein the improvement comprises the provision of greater than 0.15% of a metal which diffuses in the aluminum solid state at a rate less than that of Mn. Aluminum containing greater than 0.15% of a metal which diffuses in the aluminum solid state at a rate less than that of Mn.

  2. Behavior and Microstructure in Cryomilled Aluminum alloy Containing Diamondoids Nanoparticles

    NASA Astrophysics Data System (ADS)

    Hanna, Walid Magdy

    Aluminum (Al) alloys have been the materials of choice for both civil and military aircraft structure. Primary among these alloys are 6061 Al and 5083 Al, which have used for several structural applications including those in aerospace and automobile industry. It is desirable to enhance strength in Al alloys beyond that achieved via traditional techniques such as precipitation hardening. Recent developments have indicated strengthening via grain refinement is an effective approach since, according the Hall-Petch relation, as grain size decreases strength significantly increases. The innovate techniques of severe plastic deformation, cryomilling, are successful in reefing grain size. These techniques lead to a minimum grain size that is the result of a dynamic balance between the formation of dislocation structure and its recovery by thermal processes. According to Mohamed's model, each metal is characterized by a minimum grain size that is determined by materials parameters such as the stacking faulty energy and the activation energy for diffusion. In the present dissertation, 6061 Al and 5083 Al were synthesized using cryomilling. Microstructural characterization was extensively carried out to monitor grain size changes. A close examination of the morphology of the 6061 Al powder particles revealed that in the early milling stages, the majority of the particles changed from spheres to thin disk-shaped particles. This change was attributed to the high degree of plastic deformation generated by the impact energy during ball-powder-ball collisions. Both transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to monitor the change in grain size as a function of milling time. The results of both techniques demonstrated a close agreement with respect to two observations: (a) during cryomilling, the grain size of 6061 Al decreased with milling time, and (b) after 15 h of milling, the grain size approached a minimum value of about 22 nm, which is in

  3. 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.

  4. Effect of oxide layer formation on deformation of aluminum alloys under fire conditions

    DOE PAGES

    Yilmaz, Nadir; Vigil, Francisco M.; Tolendino, Greg; ...

    2015-05-14

    The purpose of this study is to investigate the structural behavior of aluminum alloys used in the aerospace industry when exposed to conditions similar to those of an accident scenario, such as a fuel fire. This study focuses on the role that the aluminum oxide layer plays in the deformation and the strength of the alloy above melting temperature. To replicate some of the thermal and atmospheric conditions that the alloys might experience in an accident scenario, aluminum rod specimens were subjected to temperatures near to or above their melting temperature in air, nitrogen, and vacuum environments. The characteristics ofmore » their deformation, such as geometry and rate of deformation, were observed. Tests were conducted by suspending aluminum rods vertically from an enclosure. This type of experiment was performed in two different environments: air and nitrogen. The change in environments allowed the effects of the oxide layer on the material strength to be analyzed by inhibiting the growth of the oxide layer. Observations were reported from imaging taken during the experiment showing creep behavior of aluminum alloys at elevated temperatures and time to failure. In addition, an example of tensile load–displacement data obtained in air and vacuum was reported to understand the effect of oxide layer on aluminum deformation and strength.« less

  5. Effect of oxide layer formation on deformation of aluminum alloys under fire conditions

    SciTech Connect

    Yilmaz, Nadir; Vigil, Francisco M.; Tolendino, Greg; Gill, Walt; Donaldson, A. Burl

    2015-05-14

    The purpose of this study is to investigate the structural behavior of aluminum alloys used in the aerospace industry when exposed to conditions similar to those of an accident scenario, such as a fuel fire. This study focuses on the role that the aluminum oxide layer plays in the deformation and the strength of the alloy above melting temperature. To replicate some of the thermal and atmospheric conditions that the alloys might experience in an accident scenario, aluminum rod specimens were subjected to temperatures near to or above their melting temperature in air, nitrogen, and vacuum environments. The characteristics of their deformation, such as geometry and rate of deformation, were observed. Tests were conducted by suspending aluminum rods vertically from an enclosure. This type of experiment was performed in two different environments: air and nitrogen. The change in environments allowed the effects of the oxide layer on the material strength to be analyzed by inhibiting the growth of the oxide layer. Observations were reported from imaging taken during the experiment showing creep behavior of aluminum alloys at elevated temperatures and time to failure. In addition, an example of tensile load–displacement data obtained in air and vacuum was reported to understand the effect of oxide layer on aluminum deformation and strength.

  6. 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.

  7. 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.

  8. 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.

  9. Odontologic use of copper/aluminum alloys: mitochondrial respiration as sensitive parameter of biocompatibility.

    PubMed

    Rodrigues, Luiz Erlon A; Carvalho, Antônio A V F; Azevedo, Antônio L M; Cruz, Cecília B B V; Maia, Antônio Wanderley C

    2003-01-01

    Copper/aluminum alloys are largely utilized in odontological restorations because they are less expensive than gold or platinum. However, tarnishing and important corrosion in intrabuccal prostheses made with copper/aluminum alloys after 28 days of use have been reported. Several kinds of food and beverage may attack and corrode these alloys. Copper is an essential component of several important enzymes directly involved in mitochondrial respiratory metabolism. Aluminum, in contrast, is very toxic and, when absorbed, plasma values as small as 1.65 to 21.55 microg/dl can cause severe lesions to the nervous system, kidneys, and bone marrow. Because mitochondria are extremely sensitive to minimal variation of cellular physiology, the direct relationship between the mitocondrial respiratory chain and cell lesions has been used as a sensitive parameter to evaluate cellular aggression by external agents. This work consisted in the polarographic study of mitochondrial respiratory metabolism of livers and kidneys of rabbits with femoral implants of titanium or copper/aluminum alloy screws. The experimental results obtained did not show physiological modifications of hepatic or renal mitochondria isolated from animals of the three experimental groups, which indicate good biocompatibility of copper/ aluminum alloys and suggest their odontological use.

  10. 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.

  11. An experimental investigation of fatigue damage in aluminum 2024-T3 alloys

    NASA Technical Reports Server (NTRS)

    Ferguson, Milton W.

    1993-01-01

    Aluminum alloys are finding increasing use in the aerospace and automobile industries due to their attractive low density-high modulus and low density-high strength characteristics. Unfortunately, cyclic stress-strain deformation alters the microstructure of the material. These structural changes can lead to fatigue damage and ultimately service failure. Therefore, in order to assess the integrity of the alloy, a correlation between fatigue damage and a measurable microstructural property is needed. Aluminum 2024-T3, a commonly used commercial alloy, contains many grains (individual crystals) of various orientations. The sizes and orientations of these grains are known to affect the strength, hardness, and magnetic permeability of polycrystalline alloys and metals; therefore, perhaps a relationship between a grain property and the fatigue state can be established. Tension-compression cycling in aluminum alloys can also induce changes in their dislocation densities. These changes can be studied from measurements of the electrical resistivities of the materials. Consequently, the goals of this investigation were: to study the grain orientation of aluminum 2024-T3 and to seek a correlation between the grain orientation and the fatigue state of the material; and to measure the electrical resistivities of fatigued samples of aluminum 2024-T3 and to interpret the findings.

  12. Impurity control and corrosion resistance of magnesium-aluminum alloy

    SciTech Connect

    Liu, M.; Song, GuangLing

    2013-01-01

    The corrosion resistance of magnesium alloys is very sensitive to the contents of impurity elements such as iron. In this study, a series of diecast AXJ530 magnesium alloy samples were prepared with additions of Mn and Fe. Through a comprehensive phase diagram calculation and corrosion evaluation, the mechanisms for the tolerance limit of Fe in magnesium alloy are discussed. This adds a new dimension to control the alloying impurity in terms of alloying composition design and casting conditions.

  13. 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

  14. Dielectric properties of aluminum silver alloy thin films in optical frequency range

    SciTech Connect

    Yang Guang; Sun Jingbo; Zhou Ji

    2011-06-15

    The dielectric properties of direct current (dc) magnetron sputtering aluminum silver alloy films in optical frequency have been quantitatively studied by variable angle spectroscopic ellipsometry. The structure and surface topography of the alloy films were characterized using scanning probe microscopy and x-ray diffraction. The Drude-Lorentz model was used to simulate the dielectric function of Al-Ag alloy films. Meanwhile, the effective medium theory has been utilized for the treatment of surface roughness. We found that the interband transition around 1.5 eV can be shifted through a variable annealing temperature and a changeable silver percentage of Al-Ag alloys.

  15. Effect of Aluminum Coating on the Surface Properties of Ti-(~49 at. pct) Ni Alloy

    NASA Astrophysics Data System (ADS)

    Sinha, Arijit; Khan, Gobinda Gopal; Mondal, Bholanath; Majumdar, Jyotsna Dutta; Chattopadhyay, Partha Protim

    2015-08-01

    Stable porous layer of mixed Al2O3 and TiO2 has been formed on the Ti-(~49 at. pct) Ni alloy surface with an aim to suppress leaching of Ni from the alloy surface in contact with bio-fluid and to enhance the process of osseointegration. Aluminum coating on the Ni-Ti alloy surface prior to the anodization treatment has resulted in enhancement of depth and uniformity of pores. Thermal oxidation of the anodized aluminum-coated Ni-Ti samples has exhibited the formation of Al2O3 and TiO2 phases with dense porous structure. The nanoindentation and nanoscratch measurements have indicated a remarkable improvement in the hardness, wear resistance, and adhesiveness of the porous aluminum-coated Ni-Ti sample after thermal oxidation.

  16. Theoretical calculation of positron affinities of solute clusters in aluminum alloys

    NASA Astrophysics Data System (ADS)

    Mizuno, Masataka; Araki, Hideki; Shirai, Yasuharu

    2016-01-01

    We have performed theoretical calculations of positron states for solute clusters in aluminum alloys to estimate the positron affinity of solute clusters. Positron states of solute clusters in aluminum alloys were calculated under the electronic structures obtained by first- principles molecular orbital calculations using Al158-X13 clusters. We defined the positron affinity of the solute clusters by the difference in the lowest potential sensed by positrons between the solute clusters and Al bulk. With increasing atomic number of 3d metals, the annihilation fraction of the solute clusters rapidly increases at Mn and shows a maximum at Ni. A similar trend is observed for 4d metals. The localization of positron at the solute clusters mainly arises from charge transfer from Al matrix to solute clusters. The positron affinity defined in this work well represents the localization of positron at the solute clusters in aluminum alloys.

  17. Effect of Multi-repair Welding on Fatigue Performance of Aluminum Alloy Profile Welded Joint

    NASA Astrophysics Data System (ADS)

    Diao, You-De; Shi, Chun-Yuan; Tian, Hong-Lei

    2016-05-01

    Aluminum alloy profile has been widely used in the manufacture of the rail vehicles. But it's necessary for the repair welding of the welded joints to be conducted because some defects exist in the weld such as porosity, inclusions and incomplete penetrations in the welding processes. In this paper, the influence of the multi-repair welding of 6005A aluminum alloy profile butt welded joints on the fatigue performance are investigated based on the results of fatigue tests. The parameters of curves and the fatigue strength of the welded joints are calculated, and Goodman fatigue limit diagram is also obtained. The results show that fatigue strength of aluminum alloy profile butt welded joints, in condition of 107 cycle life, meet the standard requirement for the as-welded, repair welded state one time or two times respectively.

  18. 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.

  19. Monte Carlo Modeling of Gamma Ray Backscattering for Crack Identification in the Aluminum alloy Plate

    NASA Astrophysics Data System (ADS)

    Wirawan, Rahadi; Waris, Abdul; Djamal, Mitra; Gunawan, H.; Kim, H. J.

    2017-01-01

    A Monte Carlo simulation study has been conducted of the Cs-37 gamma ray backscattering in the aluminum alloy plate. This simulation was performed in order to identify the existence of the crack in the aluminum alloy plate, the correlation between the backscattering peak and the crack width. We are able to analyze the absorbed energy distribution in the NaI(Tl) scintillation detector. For the experimental measurement, we are using 5 μCi of a Cs-137 gamma source and 2 in. x 2in. NaI(Tl) scintillation detector with the PMT. The aluminum alloy dimension is about 8 cm x 6 cm x 1 cm. The crack model is represented by the slit with the varying width (1 mm, 2 mm, 4 mm, and 6 mm). The existence of a crack is identified by the decreasing intensity of the gamma backscattering energy peak. These predicted results have a good agreement with the experimental measurement.

  20. 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.

  1. Protective Coatings for Aluminum Alloy Based on Hyperbranched 1,4-Polytriazoles.

    PubMed

    Armelin, Elaine; Whelan, Rory; Martínez-Triana, Yeimy Mabel; Alemán, Carlos; Finn, M G; Díaz, David Díaz

    2017-02-01

    Organic polymers are widely used as coatings and adhesives to metal surfaces, but aluminum is among the most difficult substrates because of rapid oxidative passivation of its surface. Poly(1,4-disubstituted 1,2,3-triazoles) made by copper-catalyzed azide-alkyne cycloaddition form strongly bonded interfaces with several metal substrates. In this work, a variety of alkyne and azide monomers were explored as precursors to anticorrosion coatings for a standard high-strength aluminum-copper alloy. Monomers of comparatively low valency (diazide and trialkyne) were found to act as superior barriers for electrolyte transfer to the aluminum surface. These materials showed excellent resistance to corrosive pitting due to the combination of three complementary properties: good formation of highly cross-linked films, as observed by Fourier transform infrared spectroscopy and differential scanning calorimetry; good adhesion to the aluminum alloy substrate, as shown by pull-off testing; and excellent impermeability, as demonstrated by electrochemical impedance spectroscopy.

  2. On Microstructural Control of Near-Threshold Fatigue Crack Growth in 7000-Series Aluminum Alloys.

    DTIC Science & Technology

    1982-04-02

    crack growth rate behavior for different microstruc - tural conditions in aluminum alloys is also in quantitative agreement with the predictions of the...34 .. . -~ Introduction ! A number of recent studies have been conducted to ascertain the influence of microstructure on fatigue crack growth behavior in aluminum...161. The da/dN data, obtained over a very broad spectrum of ,K, characterize the near-threshold growth-rate behavior unusually well. Predictions of

  3. The effect of retrogression and reaging on the properties of the 7249 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Es-Said, Omar S.; Frazier, William E.; Lee, Eui W.

    2003-01-01

    The retrogression and reaging (RRA) heat-treatment process and recent developments in high-strength 7xxx series aluminum alloys are summarized in this article. The results of experimental work indicate that RRA 7249 aluminum has the strength equivalent to or greater than 7249-T6 and superior corrosion resistance. This work is the result of collaborative efforts between the U.S. Navy and Loyola Marymount University.

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

    DTIC Science & Technology

    1938-09-30

    National Bureau of Standards for research in this fieId, and a part of these funds was used to investigate the cohmm strength of an extruded aluminum-alloy...id and discussed in part I of this report. The materkd for this investigation was supplied by the Aluminum Company of herica. Column tests were...requested by the NationaI Advisory Committee for Aeronautics. The results of these tests are presented and disoussed in part II of this report. A

  5. Investigation of the Microstructure of Joints of Aluminum Alloys Produced by Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Kolubaev, E. A.

    2015-02-01

    Special features of the microstructure of joints of aluminum-magnesium and aluminum-copper alloys produced by friction stir welding are analyzed. It is demonstrated that a layered structure with ultradisperse grains is produced by friction stir welding at the center of the weld joint. An analogy is drawn between the microstructures of joints produced by friction stir welding and surface layer produced by sliding friction.

  6. Forge Welding of Magnesium Alloy to Aluminum Alloy Using a Cu, Ni, or Ti Interlayer

    NASA Astrophysics Data System (ADS)

    Yamagishi, Hideki; Sumioka, Junji; Kakiuchi, Shigeki; Tomida, Shogo; Takeda, Kouichi; Shimazaki, Kouichi

    2015-08-01

    The forge-welding process was examined to develop a high-strength bonding application of magnesium (Mg) alloy to aluminum (Al) alloy under high-productivity conditions. The effect of the insert material on the tensile strength of the joints, under various preheat temperatures and pressures, was investigated by analyzing the reaction layers of the bonded interface. The tensile strengths resulting from direct bonding, using pure copper (Cu), pure nickel (Ni), and pure titanium (Ti) inserts were 56, 100, 119, and 151 MPa, respectively. The maximum joint strength reached 93 pct with respect to the Mg cast billet. During high-pressure bonding, a microscopic plastic flow occurred that contributed to an anchor effect and the generation of a newly formed surface at the interface, particularly prominent with the Ti insert in the form of an oxide layer. The bonded interfaces of the maximum-strength inserts were investigated using scanning electron microscopy-energy-dispersive spectroscopy and electron probe microanalysis. The diffusion reaction layer at the bonded interface consisted of brittle Al-Mg intermetallics having a thickness of approximately 30 μm. In contrast, for the three inserts, the thicknesses of the diffusion reaction layer were infinitely thin. For the pure Ti insert, exhibiting the maximum tensile strength value among the inserts tested, focused ion beam-transmission electron microscopy-EDS analysis revealed a 60-nm-thick Al-Ti reaction layer, which had formed at the bonded interface on the Mg alloy side. Thus, a high-strength Al-Mg bonding method in air was demonstrated, suitable for mass production.

  7. Fatigue Behavior of P/M 7091 and I/M 7475 Aluminum Alloys

    DTIC Science & Technology

    1989-10-01

    properties, fatigue behavior , microstruc - ture, and fractograph. TENSILE PROPERTIES Tensile test results of P/M 7091-T7E69 and l/M 7475-T7351...REPORT NO. NADC-89090-60 •1! <-.< (_ FATIGUE BEHAVIOR OF P/M 7091 AND l/M 7475 ALUMINUM ALLOYS A PA -221 79® ( Eun U. Lee . Air Vehicle and... Behavior of P/M 7091 and I/M 7475 Aluminum Alloys 12. PERSONAL AUTHOR(S) Eun U. Lee 13a. TYPE OF REPORT Phase 13b. TIME COVERED FROM TO 14. DATE

  8. Niobium-aluminum base alloys having improved, high temperature oxidation resistance

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G. (Inventor); Stephens, Joseph R. (Inventor)

    1991-01-01

    A niobium-aluminum base alloy having improved oxidation resistance at high temperatures and consisting essentially of 48%-52% niobium, 36%-42% aluminum, 4%-10% chromium, 0%-2%, more preferably 1%-2%, silicon and/or tungsten with tungsten being preferred, and 0.1%-2.0% of a rare earth selected from the group consisting of yttrium, ytterbium and erbium. Parabolic oxidation rates, k.sub.p, at 1200.degree. C. range from about 0.006 to 0.032 (mg/cm.sup.2).sup.2 /hr. The new alloys also exhibit excellent cyclic oxidation resistance.

  9. 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.

  10. The Variability of Fatigue Crack Growth Life of Aluminum Casting Alloy A357-T6

    DTIC Science & Technology

    1986-07-01

    34,FWAL-TR-86-4115 . A THE VARIABILITY OF FATIGUE CRACK GROWTH LIFE OF ALUMINUM CASTING ALLOY A357 -T6 .D. TIRPAK, CAPT, USAF Materials Engineering...Fatigue Crack Growth Life of Aluminum Casting Alloy A357 -T6 17 COSATI CODES 18. SUBJECT 1%iRMS (Continue on reverse if necessary and identify by...fContinue on reverse if necessary and identify by block number) "This investigation considers the variability of fatigue crack growth (FCG) life of A357 -T6

  11. Multi-Response Optimization of Friction-Stir-Welded AA1100 Aluminum Alloy Joints

    NASA Astrophysics Data System (ADS)

    Rajakumar, S.; Balasubramanian, V.

    2012-06-01

    AA1100 aluminum alloy has gathered wide acceptance in the fabrication of light weight structures. Friction stir welding process (FSW) is an emerging solid state joining process in which the material that is being welded does not melt and recast. The process and tool parameters of FSW play a major role in deciding the joint characteristics. In this research, the relationships between the FSW parameters (rotational speed, welding speed, axial force, shoulder diameter, pin diameter, and tool hardness) and the responses (tensile strength, hardness, and corrosion rate) were established. The optimal welding conditions to maximize the tensile strength and minimize the corrosion rate were identified for AA1100 aluminum alloy and reported here.

  12. Corrosion characterization of aluminum alloys treated with a new sealing process -- Part 2

    SciTech Connect

    Banerjee, G.; Miller, A.E.; Vasanth, K.L.

    1999-07-01

    Continuing an earlier investigation a new sealing solution that contains catalytic amount of chromium (1--10{micro}g) was developed. Aluminum alloys 2024-T6 and 6061-T6 coupons were anodized and sealed with the new sealing formulation. Passivation characteristics of these samples were evaluated using potentiodynamic anodic polarization tests. Al 6061-T6 coupons were further subjected to prohesion tests. In this paper, the results obtained from these tests are compared to those obtained by aluminum alloy treated with standard chromate conversion coating.

  13. The triggering of steam explosions of single drops of pure and alloyed molten aluminum

    SciTech Connect

    Nelson, L.S.; Fuketa, T.; Eatough, M.J.; Vigil, F.J. )

    1990-06-01

    When a hot liquid (fuel) comes into contact with a cold liquid (coolant), a variety of different fuel/coolant interactions (FCIs) can occur. For certain research on production reactors, the coolant of interest is water (either H{sub 2}O or D{sub 2}O), while the fuel is a molten alloy based mainly on aluminum and uranium. Aluminum-based melts have been shown to be explosive in many experiments performed by the aluminum industry and in several reactor experiments and accidents including NRX, SPERT, BORAX, etc. In the aluminum industry, steam explosions continue to result in property damage, personal injuries, and deaths. It is also known that certain alloying components, notably lithium, can enhance the strength of the explosions as well as the probability of their occurrence. To obtain quantitative information relating to the FCIs that might occur with uranium-aluminum fuel, a laboratory-scale experimental scoping study was begun at Sandia National Laboratories. The overall objective of this research program is to provide an understanding of the mechanism of steam explosions with the melt compositions expected in various hypothetical core meltdown accident scenarios in production reactors. In this program, it has been demonstrated that reproducible triggering of steam explosions with pure and alloyed aluminum can be achieved with both focused and unfocused shock waves generated with underwater electrical discharges.

  14. 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.

  15. Aging Optimization of Aluminum-Lithium Alloy L277 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H.; Farahmand, B.; Cho, A.

    2003-01-01

    Compared with aluminum alloys such as 2219, which is widely used in space vehicle for cryogenic tanks and unpressurized structures, aluminum-lithium alloys possess attractive combinations of lower density and higher modulus along with comparable mechanical properties and improved damage tolerance. These characteristics have resulted in the successful use of the aluminum-lithium alloy 2195 for the Space Shuttle External Tank, and the consideration of newer U.S. aluminum-lithium alloys such as L277 and C458 for future space vehicles. A design of experiments aging study was conducted for plate and a limited study on extrusions. To achieve the T8 temper, Alloy L277 is typically aged at 290 F for 40 hours. In the study for plate, a two-step aging treatment was developed through a design of experiments study and the one step aging used as a control. Based on the earlier NASA studies on 2195, the first step aging temperature was varied between 220 F and 260 F. The second step aging temperatures was varied between 290 F and 310 F, which is in the range of the single-step aging temperature. For extrusions, two, single-step, and one two-step aging condition were evaluated. The results of the design of experiments used for the T8 temper as well as a smaller set of experiments for the T6 temper for plate and the results for extrusions will be presented.

  16. Redistribution Mechanisms and Quantification of Homogeneity in Friction Stir Welding and Processing of an Aluminum Silicon Alloy

    DTIC Science & Technology

    2012-09-01

    wide range of particle-containing materials. Materials such as Nickel Aluminum Bronze (NAB), high yield (HY) Steels , and AA5083 are common in many...REDISTRIBUTION MECHANISMS AND QUANTIFICATION OF HOMOGENEITY IN FRICTION STIR WELDING AND PROCESSING OF AN ALUMINUM SILICON ALLOY by Jeffrey C. Woertz...Homogeneity in Friction Stir Welding and Processing of an Aluminum Silicon Alloy 5. FUNDING NUMBERS 6. AUTHOR(S) Jeffrey C. Woertz 7

  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. 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%.

  19. 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.

  20. 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)

  1. Thermodynamic analysis of contamination by alloying elements in aluminum recycling.

    PubMed

    Nakajima, Kenichi; Takeda, Osamu; Miki, Takahiro; Matsubae, Kazuyo; Nakamura, Shinichiro; Nagasaka, Tetsuya

    2010-07-15

    In previous studies on the physical chemistry of pyrometallurgical processing of aluminum scrap, only a limited number of thermodynamic parameters, such as the Gibbs free energy change of impurity reactions and the variation of activity of an impurity in molten aluminum, were taken into account. In contrast, in this study we thermodynamically evaluated the quantitative removal limit of impurities during the remelting of aluminum scrap; all relevant parameters, such as the total pressure, the activity coefficient of the target impurity, the temperature, the oxygen partial pressure, and the activity coefficient of oxidation product, were considered. For 45 elements that usually occur in aluminum products, the distribution ratios among the metal, slag, and gas phases in the aluminum remelting process were obtained. Our results show that, except for elements such as Mg and Zn, most of the impurities occurred as troublesome tramp elements that are difficult to remove, and our results also indicate that the extent to which the process parameters such as oxygen partial pressure, temperature, and flux composition can be changed in aluminum production is quite limited compared to that for iron and copper production, owing to aluminum's relatively low melting point and strong affinity for oxygen. Therefore, the control of impurities in the disassembly process and the quality of scrap play important roles in suppressing contamination in aluminum recycling.

  2. The galvanic corrosion behavior of depleted uranium in synthetic seawater coupled to aluminum, magnesium, and mild steel

    SciTech Connect

    McIntyre, J.F.; LeFeave, E.P.; Musselman, K.A.

    1987-01-01

    The galvanic corrosion behavior of a depleted uranium-titanium alloy (Du-.75Ti) coupled to MgZk60A-T5, AA-7075-T6, bare steel-4340, and coated steel-4340 exposed to ASTM seawater was investigated by monitoring the galvanic current with time. Gravimetric measurements, polarization resistance measurements, and concepts of ''mixed-potential'' theory were used to calculate corrosion rates. It was demonstrated that galvanic currents must be monitored over extended periods of time to detect changes in the galvanic corrosion behavior. Good agreement was obtained for corrosion rates calculated using the concepts of ''mixed-potential'' theory and those obtained from gravimetric measurements.

  3. Processing, microstructure evolution and properties of nanoscale aluminum alloys

    NASA Astrophysics Data System (ADS)

    Han, Jixiong

    In this project, phase transformations and precipitation behavior in age-hardenable nanoscale materials systems, using Al-Cu alloys as model materials, were first studied. The Al-Cu nanoparticles were synthesized by a Plasma Ablation process and found to contain a 2˜5 nm thick adherent aluminum oxide scale, which prevented further oxidation. On aging of the particles, a precipitation sequence consisting of, nearly pure Cu precipitates to the metastable theta' to equilibrium theta was observed, with all three forming along the oxide-particle interface. The structure of theta' and its interface with the Al matrix has been characterized in detail. Ultrafine Al-Cu nanoparticles (5˜25 nm) were also synthesized by inert gas condensation (IGC) and their aging behavior was studied. These particles were found to be quite stable against precipitation. Secondly, pure Al nanoparticles were prepared by the Exploding Wire process and their sintering and consolidation behavior were studied. It was found that nanopowders of Al could be processed to bulk structures with high hardness and density. Sintering temperature was found to have a dominant effect on density, hardness and microstructure. Sintering at temperatures >600°C led to breakup of the oxide scale, leading to an interesting nanocomposite composed of 100˜200 nm Al oxide dispersed in a bimodal nanometer-micrometer size Al matrix grains. Although there was some grain growth, the randomly dispersed oxide fragments were quite effective in pinning the Al grain boundaries, preventing excessive grain growth and retaining high hardness. Cold rolling and hot rolling were effective methods for attaining full densification and high hardness. Thirdly, the microstructure evolution and mechanical behavior of Al-Al 2O3 nanocomposites were studied. The composites can retain high strength at elevated temperature and thermal soaking has practically no detrimental effect on strength. Although the ductility of the composite remains

  4. Hot hardness of nickel-rich nickel-chromium-aluminum alloys

    NASA Technical Reports Server (NTRS)

    Levine, S. R.

    1976-01-01

    Rockwell A hardness of cast nickel-chromium-aluminum (NiCrAl) alloys was examined from ambient to 1150 K and compared to cast NiAl and IN-100. Alloy constitution was either gamma, gamma prime + gamma or gamma + beta + alpha + gamma prime. Below 1000 K beta containing NiCrAl alloys have hardnesses comparable to IN-100; above 1000 K they soften faster than IN-100. At 1150 K the hardness of beta-containing NiCrAl alloys decreases with increasing beta-content. The beta-containing NiCrAl alloys were harder than beta-NiAl. The ultimate tensile strengths of the NiCrAl alloys were estimated. The effects of NiCrAl coatings on strength and fatigue life of cooled turbine components were deduced.

  5. Production of Gas-Solid Structures in Aluminum and Nickel Alloys by Gasar Processing

    SciTech Connect

    Apprill, J.M.; Baldwin, M.D.; Maguire, M.C.; Miszkiel, M.E.; Shapovalov, V.I.

    1999-01-06

    Experimental data on directional and bulk solidification of hydrogen-charged samples of aluminum alloy A356 and nickel alloy Inconel 718 are discussed. The solidification structure of the porous zone is shown to be dependent on many process variables. Of these variables, hydrogen content in the melt prior to solidification, and furnace atmospheric pressure during solidification play the decisive role. Also important are the furnace atmosphere composition, the solidification velocity, and the temperature distribution of the liquid metal inside the mold.

  6. Laser welding of automotive aluminum alloys to achieve defect-free, structurally sound and reliable welds

    SciTech Connect

    DebRoy, T.

    2000-11-17

    The objective of this program was to seek improved process control and weldment reliability during laser welding of automotive aluminum alloys while retaining the high speed and accuracy of the laser beam welding process. The effects of various welding variables on the loss of alloying elements and the formation of porosity and other geometric weld defects such as underfill and overfill were studied both experimentally and theoretically.

  7. Aging Optimization of Aluminum-Lithium Alloy C458 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H.; Farahmand, B.; Rioja, R.

    2003-01-01

    Compared with aluminum alloys such as 2219, which is widely used in space vehicle for cryogenic tanks and unpressurized structures, aluminum-lithium alloys possess attractive combinations of lower density and higher modulus along with comparable mechanical properties. These characteristics have resulted in the successful use of the aluminum-lithium alloy 2195 (Al-1.0 Li-4.0 Cu-0.4 Mg-0.4 Ag-0.12 Zr) for the Space Shuttle External Tank, and the consideration of newer U.S. aluminum-lithium alloys such as L277 and C458 for future space vehicles. These newer alloys generally have lithium content less than 2 wt. % and their composition and processing have been carefully tailored to increase the toughness and reduce the mechanical property anisotropy of the earlier generation alloys such 2090 and 8090. Alloy processing, particularly the aging treatment, has a significant influence on the strength-toughness combinations and their dependence on service environments for aluminum-lithium alloys. Work at NASA Marshall Space Flight Center on alloy 2195 has shown that the cryogenic toughness can be improved by employing a two-step aging process. This is accomplished by aging at a lower temperature in the first step to suppress nucleation of the strengthening precipitate at sub-grain boundaries while promoting nucleation in the interior of the grains. Second step aging at the normal aging temperature results in precipitate growth to the optimum size. A design of experiments aging study was conducted for plate. To achieve the T8 temper, Alloy C458 (Al-1.8 Li-2.7 Cu-0.3 Mg- 0.08 Zr-0.3 Mn-0.6 Zn) is typically aged at 300 F for 24 hours. In this study, a two-step aging treatment was developed through a comprehensive 24 full factorial design of experiments study and the typical one-step aging used as a reference. Based on the higher lithium content of C458 compared with 2195, the first step aging temperature was varied between 175 F and 250 F. The second step aging temperatures was

  8. Development and Processing Improvement of Aerospace Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Lisagor, W. Barry; Bales, Thomas T.

    2007-01-01

    This final report, in multiple presentation format, describes a comprehensive multi-tasked contract study to improve the overall property response of selected aerospace alloys, explore further a newly-developed and registered alloy, and correlate the processing, metallurgical structure, and subsequent properties achieved with particular emphasis on the crystallographic orientation texture developed. Modifications to plate processing, specifically hot rolling practices, were evaluated for Al-Li alloys 2195 and 2297, for the recently registered Al-Cu-Ag alloy, 2139, and for the Al-Zn-Mg-Cu alloy, 7050. For all of the alloys evaluated, the processing modifications resulted in significant improvements in mechanical properties. Analyses also resulted in an enhanced understanding of the correlation of processing, crystallographic texture, and mechanical properties.

  9. Superplastic behavior in a commercial 5083 aluminum alloy

    SciTech Connect

    Vetrano, J.S.; Lavender, C.A.; Smith, M.T.; Bruemmer, S.M. ); Hamilton, C.H. . Dept. of Mechanical and Materials Engineering)

    1994-03-01

    When considering the forming and post-forming properties required of a superplastic material, attractive candidates are commercial Al-Mg-Mn weldable alloys such as AA5083. There have been several investigations of hot deformation of 5083-type alloys in the literature. Only two studies evaluated commercial-purity 5083 and they achieved tensile elongations of 150% and 200%. Alloy modification has produced improved behavior in three 5083-type alloys developed specifically for SPF. Two were deemed high-purity 5083 (low Fe and Si) and achieved elongations of 450% and 630%. Engineering strains up to 700% were measured by Watanabe et al. in a 5083-based alloy with the addition of 0.6% Cu as a grain refiner. These results suggest that alloy modifications such as reduced Fe and Si contents or Cu additions may be required to improve superplastic response. Unfortunately, specific SPF-grade 5083 alloys are substantially more expensive than the commercial grade, and the addition of Cu decreases the corrosion resistance of the base material. The purpose of this work is to examine the effect of prior degrees of cold work on the SPF behavior of a standard-grade 5083 alloy. Superplastic behavior of this material at 510[degree]C is assessed and compared to published results for the SPF-grade alloys.

  10. Advantages of Oxide Films as Bases for Aluminum Pigmented Surface Coatings for Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Buzzard, R W; Mutchler, W H

    1931-01-01

    Both laboratory and weather-exposure corrosion tests showed conclusively that the protection afforded by aluminum pigmented spar varnish coatings applied to previously anodized aluminum surfaces was greatly superior to that afforded by the same coatings applied to surfaces which had simply been cleaned free from grease and not anodized.

  11. Aluminum for bonding Si-Ge alloys to graphite

    DOEpatents

    Eggemann, Robert V.

    1976-01-13

    Improved thermoelectric device and process, comprising the high-temperature, vacuum bonding of a graphite contact and silicon-germanium thermoelectric element by the use of a low void, aluminum, metallurgical shim with low electrical resistance sandwiched therebetween.

  12. A microstructural study of flash welded and aged 6061 and 6013 aluminum alloys

    SciTech Connect

    Barbosa, C.; Dille, J.; Delplancke, J.-L.; Rebello, J.M.A.

    2006-09-15

    Extruded, flash welded and artificially aged 6061 and 6013 aluminum alloys were analyzed with the use of techniques such as transmission electron microscopy (TEM) imaging, selected area electron diffraction (SAD) and X-ray energy-dispersive spectroscopy (EDS) in order to identify the precipitates present in both alloys. Vickers microindentation hardness measurements were performed at different distances from the weld interface. The results show a small decrease in hardness near the 6013 alloy weld interface. On the other hand, there is an important hardness drop near the 6061 weld interface. This drop can be explained by a lack of fine structural precipitation during the aging treatment in the 6061 weld interface zone.

  13. Transmission electron microscopy characterization of microstructural features in aluminum-lithium-copper alloys

    NASA Technical Reports Server (NTRS)

    Avalos-Borja, M.; Larson, L. A.; Pizzo, P. P.

    1984-01-01

    A transmission electron microscopy (TEM) examination of aluminum-lithium-copper alloys was conducted. The principal purpose is to characterize the nature, size, and distribution of stringer particles which result from the powder metallurgy (P/M) processing of these alloys. Microstructural features associated with the stringer particles are reported that help explain the stress corrosion susceptibility of the powder metallurgy-processed Al-Li-Cu alloys. In addition, matrix precipitaton events are documented for a variety of heat treatments and process variations. Hot rolling is observed to significantly alter the nature of matrix precipitation, and the observations are correlated with concomitant mechanical property variations.

  14. Atmospheric Corrosion of Aluminum Alloy 3105 in Coastal Environments: Interim Report After 15 Months Exposure

    SciTech Connect

    Holcomb, G.R.

    1996-04-19

    In May of 1994, racks of corrosion samples were installed along the Oregon coast. The aluminum alloy 3105 samples were mounted on utility poles in Astoria, Manzanita, Lincoln City, Gold Beach, Brookings, Portland, and Albany. At each coastal location, samples were placed on four different poles at various distances from the coast (from as near as 50 feet to as far as 5 miles). The inland sites (Portland and Albany) have only one pole per site and are used as control sites. Besides the 3105 alloys, 5052 and 6061 aluminum alloys were placed at all sites. Since installation, one rack was lost due to the pole being taken down by the phone company (in Lincoln City), but the rest of the poles and racks are still in place.

    In August of 1995, the aluminum samples were visually inspected, and the remaining six 3105 aluminum samples in Lincoln City were removed for laboratory examination. Non-destructive x-ray analysis was used on the Lincoln City samples to obtain information a bout the nature of the corrosion products. Because the analysis was performed while the corrosion products remained on the surface, aluminum peaks dominated the diffraction pattern, and relative peak-heights were different from normal. Nevertheless, some minerals were identified as part of the corrosion products.

  15. The Role of Stress in the Corrosion Cracking of Aluminum Alloys

    DTIC Science & Technology

    2013-03-01

    50 Figure 42. Crack Orientations for Rolled Plate Material . From [18] ................................53 xi LIST OF TABLES...Increasing transverse stability allows the ship to be operated in higher sea states that would normally prohibit the safe operation of the ship. This...alloying addition in 5000 series aluminum is magnesium, which gives the material good specific strength and general corrosion properties and is also

  16. Fractographic analysis of the low energy fracture of an aluminum alloy

    NASA Technical Reports Server (NTRS)

    Tanaka, J.; Pampillo, C. A.; Low, J. R., Jr.

    1972-01-01

    A study of the fracture process in a high strength aluminum alloy, 2014T6, was undertaken to identify the void nucleating particles in this material, to determine their composition, and to suggest means by which they might be eliminated without loss of strength.

  17. 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.

  18. Single-point incremental forming of 2024-T3 aluminum alloy sheets

    NASA Astrophysics Data System (ADS)

    Li, Xiaoqiang; Yu, Honghan; Guo, Guiqiang; Li, Dongsheng

    2013-12-01

    Many aluminum alloy sheet metal parts with complex geometry in airplane are often formed by drop hammer forming with intermediate annealing and then heat treated into T temper. The manufacturing cost is very high because of a number of forming and heat treatment steps. Incremental sheet forming can form complex parts because of larger forming limit than conventional stamping. So the research that the part is formed directly from T temper aluminum alloy sheet using incremental sheet forming is very attractive. 2024-T3 is the aluminum alloy used mostly in aerospace manufacturing. Single-point incremental forming experiments with 2024-T3 are carried to form cone shape parts. In this work, the formability of 2024-T3 aluminum alloy sheets in single-point incremental forming was preliminarily studied. Effect of tool diameter and wall angle on the formability were investigated. It is found that the surface roughness can be reduced and the forming depth of the cone shape part can be increased by increasing the tool diameter.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Effects of Cryogenic Treatment on the Residual Stress and Mechanical Properties of an Aerospace Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Chen, Po; Malone, Tina; Bod, Robert; Torres, Pablo

    2000-01-01

    Investigators at Marshall Space Flight Center (MSFC) are studying the potential benefits of cryogenic treatment for aerospace Aluminum (Al) alloys. This paper reports the effects of cryogenic treatment on residual stress, tensile strength, hardness, fatigue life, and stress corrosion cracking (SCC) resistance.

  4. Effects of Cryogenic Treatment on the Residual Stress and Mechanical Properties of an Aerospace Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Chen, P.; Malone, T.; Bond, R.; Torres, P.

    2001-01-01

    Investigators at Marshall Space Flight Center (MSFC) are studying the potential benefits of cryogenic treatment for aerospace Aluminum (Al) alloys. This paper reports the effects of cryogenic treatment on residual stress, tensile strength, hardness, fatigue life, and stress corrosion cracking (SCC) resistance.

  5. 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.

  6. Genetically engineered peptides for inorganics: study of an unconstrained bacterial display technology and bulk aluminum alloy.

    PubMed

    Adams, Bryn L; Finch, Amethist S; Hurley, Margaret M; Sarkes, Deborah A; Stratis-Cullum, Dimitra N

    2013-09-06

    The first-ever peptide biomaterial discovery using an unconstrained engineered bacterial display technology is reported. Using this approach, we have developed genetically engineered peptide binders for a bulk aluminum alloy and use molecular dynamics simulation of peptide conformational fluctuations to demonstrate sequence-dependent, structure-function relationships for metal and metal oxide interactions.

  7. Comparative Evaluation of Cast Aluminum Alloys for Automotive Cylinder Heads: Part I—Microstructure Evolution

    NASA Astrophysics Data System (ADS)

    Roy, Shibayan; Allard, Lawrence F.; Rodriguez, Andres; Watkins, Thomas R.; Shyam, Amit

    2017-03-01

    The present study stages a comparative evaluation of microstructure and associated mechanical and thermal response for common cast aluminum alloys that are used for manufacturing automotive cylinder heads. The systems considered are Al-Cu (206-T6), Al-Si-Cu (319-T7), and Al-Si (356-T6, A356-T6, and A356 + 0.5Cu-T6). The focus of the present manuscript is on the evaluation of microstructure at various length scales after aging, while the second manuscript will deal with the mechanical and thermal response of these alloys due to short-term (aging) and long-term (pre-conditioning) heat treatments. At the grain-scale, the Al-Cu alloy possessed an equiaxed microstructure as opposed to the dendritic structure for the Al-Si-Cu or Al-Si alloys which is related to the individual solidification conditions for these alloy systems. The composition and morphology of intermetallic precipitates within the grain and at the grain/dendritic boundary are dictated by the alloy chemistry, solidification, and heat treatment conditions. At the nanoscale, these alloys contain various metastable strengthening precipitates (GPI and θ^'' in Al-Cu alloy, θ^' in Al-Si-Cu alloy, and β^' in Al-Si alloys) with varying size, morphology, coherency, and thermal stability.

  8. 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.

  9. Precipitation hardening in the first aerospace aluminum alloy: the wright flyer crankcase.

    PubMed

    Gayle, F W; Goodway, M

    1994-11-11

    Aluminum has had an essential part in aerospace history from its very inception: An aluminum copper alloy (with a copper composition of 8 percent by weight) was used in the engine that powered the historic first flight of the Wright brothers in 1903. Examination of this alloy shows that it is precipitation-hardened by Guinier-Preston zones in a bimodal distribution, with larger zones (10 to 22 nanometers) originating in the casting practice and finer ones (3 nanometers) resulting from ambient aging over the last 90 years. The precipitation hardening in the Wright Flyer crankcase occurred earlier than the experiments of Wilm in 1909, when such hardening was first discovered, and predates the accepted first aerospace application of precipitation-hardened aluminum in 1910.

  10. Microstructural effects on the tensile and fracture behavior of aluminum casting alloys A356/357

    NASA Astrophysics Data System (ADS)

    Wang, Q. G.

    2003-12-01

    The tensile properties and fracture behavior of cast aluminum alloys A356 and A357 strongly depend on secondary dendrite arm spacing (SDAS), Mg content, and, in particular, the size and shape of eutectic silicon particles and Fe-rich intermetallics. In the unmodified alloys, increasing the cooling rate during solidification refines both the dendrites and eutectic particles and increases ductility. Strontium modification reduces the size and aspect ratio of the eutectic silicon particles, leading to a fairly constant particle size and aspect ratio over the range of SDAS studied. In comparison with the unmodified alloys, the Sr-modified alloys show higher ductility, particularly the A356 alloy, but slightly lower yield strength. In the microstructures with large SDAS (>50 µm), the ductility of the Sr-modified alloys does not continuously decrease with SDAS as it does in the unmodified alloy. Increasing Mg content increases both the matrix strength and eutectic particle size. This decreases ductility in both the Sr-modified and unmodified alloys. The A356/357 alloys with large and elongated particles show higher strain hardening and, thus, have a higher damage accumulation rate by particle cracking. Compared to A356, the increased volume fraction and size of the Fe-rich intermetallics ( π phase) in the A357 alloy are responsible for the lower ductility, especially in the Sr-modified alloy. In alloys with large SDAS (>50 µm), final fracture occurs along the cell boundaries, and the fracture mode is transgranular. In the small SDAS (<30 µm) alloys, final fracture tends to concentrate along grain boundaries. The transition from transgranular to intergranular fracture mode is accompanied by an increase in the ductility of the alloys.

  11. 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).

  12. 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.

  13. The Cryogenic Properties of Several Aluminum-Beryllium Alloys and a Beryllium Oxide Material

    NASA Technical Reports Server (NTRS)

    Gamwell, Wayne R.; McGill, Preston B.

    2003-01-01

    Performance related mechanical properties for two aluminum-beryllium (Al-Be) alloys and one beryllium-oxide (BeO) material were developed at cryogenic temperatures. Basic mechanical properties (Le., ultimate tensile strength, yield strength, percent elongation, and elastic modulus were obtained for the aluminum-beryllium alloy, AlBeMetl62 at cryogenic [-195.5"C (-320 F) and -252.8"C (-423"F)I temperatures. Basic mechanical properties for the Be0 material were obtained at cyrogenic [- 252.8"C (-423"F)] temperatures. Fracture properties were obtained for the investment cast alloy Beralcast 363 at cryogenic [-252.8"C (-423"F)] temperatures. The AlBeMetl62 material was extruded, the Be0 material was hot isostatic pressing (HIP) consolidated, and the Beralcast 363 material was investment cast.

  14. The Mechanical Behavior of Friction-Stir Spot Welded Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Güler, Hande

    2014-10-01

    Aluminum and alloys are widely used in the automotive industry due to the light weight, good formability, and malleability. Spot welding is the most commonly used joining method of these materials, but the high current requirements and the inconsistent quality of the final welds make this process unsuitable. An alternative welding technique, the friction-stir spot welding process, can also be successfully used in joining of aluminum and alloys. In this study, 1-mm-thick AA5754 Al-alloy plates in the H-111 temper conditions were joined by friction-stir spot welding using two different weld parameters such as tool rotational speed and dwell time. Mechanical properties of the joints were obtained with extensive hardness measurements and tensile shear tests. The effect of these parameters on the failure modes of welded joints was also determined.

  15. Method of preparing an electrode material of lithium-aluminum alloy

    DOEpatents

    Settle, Jack L.; Myles, Kevin M.; Battles, James E.

    1976-01-01

    A solid compact having a uniform alloy composition of lithium and aluminum is prepared as a negative electrode for an electrochemical cell. Lithium losses during preparation are minimized by dissolving aluminum within a lithium-rich melt at temperatures near the liquidus temperatures. The desired alloy composition is then solidified and fragmented. The fragments are homogenized to a uniform composition by annealing at a temperature near the solidus temperature. After comminuting to fine particles, the alloy material can be blended with powdered electrolyte and pressed into a solid compact having the desired electrode shape. In the preparation of some electrodes, an electrically conductive metal mesh is embedded into the compact as a current collector.

  16. 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.

  17. 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.

  18. Properties of the joints of sheets of 1565ch alloy in combination with other aluminum alloys that were performed by friction welding with mixing

    NASA Astrophysics Data System (ADS)

    Drits, A. M.; Ovchinnikov, V. V.

    2016-06-01

    The structure and properties of the butt-welded joints of a 1565ch M aluminum alloy with AMg5, AMg6, AV (60661), and 7021 alloys that were performed by friction welding with mixing are studied. The mechanical properties of these joints and their fracture zones are determined as functions of a combination of the alloys to be joined. These alloys are found to have good weldability under friction welding with mixing.

  19. Corrosion protection of Al alloys and Al-based metal-matrix composites by chemical passivation

    SciTech Connect

    Mansfeld, F.; Lin, S.; Sim, S.; Shih, H.

    1989-08-01

    Chemical passivation by immersion of aluminium alloys and aluminium 6061/ silicon carbide and aluminium 6061/graphite metal-matrix composites in cerium chloride solution produces very corrosion-resistant surfaces. Aluminium 6061 and aluminium 7075-T6 that had been immersed in 1000 ppm cerium chloride for one week did not suffer from pitting corrosion during immersion in acerated 0.5 N NaCl for three weeks. For aluminium 7075-T7l3 some improvement of the corrosion resistance was also achieved, but to a much lesser extent. Chemical passivation in cerium chloride was also successful for aluminium/silicon carbide and Allgraphite.

  20. Identification of heat treatments for better formability in an aluminum-lithium alloy sheet

    NASA Astrophysics Data System (ADS)

    Bairwa, M. L.; Desai, Sharvari G.; Date, P. P.

    2005-10-01

    Research in the weight of an automobile is a continuous process among auto manufacturers. The “body in white” (BIW, i.e., the body of the car) deserves attention, being a major contributor to the weight of the vehicle. By virtue of a high strength to weight ratio (density smaller than aluminum) and a higher Young’s modulus than aluminum, aluminum-lithium alloy sheet appears to hold promise as an autobody material. Because auto components are required in large numbers and are formed at room temperature, formability under these conditions becomes significant. Aluminum-lithium alloys acquire, because of aging over a short period of time, a good amount of strength and hence dent resistance. In principle, they can be given, through suitable heat treatments, a high formability as well as dent resistance, i.e., an ideal combination of properties. To this end, tensile properties have been determined for a number of heat treatments comprising three different solutionizing temperatures and for three aging times at each of the three aging temperatures. Considerable influence of heat treatment was observed on the mechanical properties (which in turn characterize both formability and dent resistance), such as the strain hardening exponent, average normal anisotropy, yield stress, ultimate tensile stress, and percentage elongation to failure. For each property, the best three heat treatments leading to a high formability were identified. Consequently, heat treatments that imparted the greatest formability for processes such as deep drawing and stretch forming have been identified. The investigations show that the best heat treatment for one property may not be the best for another property, calling for a compromise to obtain the most practicable heat treatment schedule. Results shed light on not only the biaxial formability but also springback behavior that is important in the BIW components. Further, the properties obtained from the heat treatment giving good formability

  1. Properties of splat-quenched 7075 aluminum type alloys

    NASA Technical Reports Server (NTRS)

    Durand, J. P. H. A.; Pelloux, R. M.; Grant, N. J.

    1976-01-01

    The 7075 alloy belonging to the Al-Zn-Mg-Cu system, prepared by powder metallurgy techniques, was used in a study of alloys prepared from splat-quenched foils consolidated into bar material by hot extrusion. Ni and Fe were included in one alloy specimen, producing a fine dispersion of FeAl3 type particles which added to the strength of the aged alloy but did not coarsen upon heat treatment. Fine oxide films showing up on air-splatted foils induce finely dispersed oxide stringers (if the foils are not hot-worked subsequently) which in turn promote axial cracking (but longitudinal tensile strength is not seriously impaired). Splatting in a protective atmosphere, or thermomechanical processing, is recommended to compensate for this.

  2. Fabrication of surface self-lubricating composites of aluminum alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Wenjing; Zhang, Dong; Le, Yongkang; Li, Lian; Ou, Bin

    2008-12-01

    Porous aluminum anodic oxide films fabricated by anodizing in phosphoric acid electrolyte containing organic acid were investigated. By controlling its microstructure, a macroporous and thick alumina template were obtained. Surface self-lubricating composites were prepared by taking ultra-sonic impregnation in PTFE latex and the relative subsequent heat treatment technology. The studies on the tribological behavior of the surface self-lubricating composite indicated that the tribological properties of aluminum surface can be improved obviously. Compared with the surface coating of hard-anodization, the friction coefficient of self-lubricating composite can be effectively reduced from the 0.575 to 0.166.

  3. Grain Boundary Segregation and Stress Corrosion Cracking of Aluminum Alloys

    DTIC Science & Technology

    1976-11-01

    consider the following: i) Generation of byd- ogen ii) Entry of hydrogen through the protective surface filmi and iii) Concentration of hydrogen in a...Mechanisms of cracking Hydrogen einbrittlernent Grain boundary segregation Oxide filris Alumrinum’n Alloys 20. A STT ACT (Cori(Itue on revors• side It ,rece...grain boundary segregation profiles of various alunminum ll oys. Samnples of both cornommercial ( 7075 , 7050, and 749) and high purity alloys based on the

  4. 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.

  5. Removing hydrochloric acid exhaust products from high performance solid rocket propellant using aluminum-lithium alloy.

    PubMed

    Terry, Brandon C; Sippel, Travis R; Pfeil, Mark A; Gunduz, I Emre; Son, Steven F

    2016-11-05

    Hydrochloric acid (HCl) pollution from perchlorate based propellants is well known for both launch site contamination, as well as the possible ozone layer depletion effects. Past efforts in developing environmentally cleaner solid propellants by scavenging the chlorine ion have focused on replacing a portion of the chorine-containing oxidant (i.e., ammonium perchlorate) with an alkali metal nitrate. The alkali metal (e.g., Li or Na) in the nitrate reacts with the chlorine ion to form an alkali metal chloride (i.e., a salt instead of HCl). While this technique can potentially reduce HCl formation, it also results in reduced ideal specific impulse (ISP). Here, we show using thermochemical calculations that using aluminum-lithium (Al-Li) alloy can reduce HCl formation by more than 95% (with lithium contents ≥15 mass%) and increase the ideal ISP by ∼7s compared to neat aluminum (using 80/20 mass% Al-Li alloy). Two solid propellants were formulated using 80/20 Al-Li alloy or neat aluminum as fuel additives. The halide scavenging effect of Al-Li propellants was verified using wet bomb combustion experiments (75.5±4.8% reduction in pH, ∝ [HCl], when compared to neat aluminum). Additionally, no measurable HCl evolution was detected using differential scanning calorimetry coupled with thermogravimetric analysis, mass spectrometry, and Fourier transform infrared absorption.

  6. 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.

  7. Detection and removal of molten salts from molten aluminum alloys

    SciTech Connect

    K. Butcher; D. Smith; C. L. Lin; L. Aubrey

    1999-08-02

    Molten salts are one source of inclusions and defects in aluminum ingots and cast shapes. A selective adsorption media was used to remove these inclusions and a device for detection of molten salts was tested. This set of experiments is described and the results are presented and analyzed.

  8. WETTING AND BONDING BETWEEN ALUMINUM ALLOYS AND SAPPHIRE.

    DTIC Science & Technology

    equilibrium contact angle ; the lowest contact angle observed was 94 degrees and was obtained with 0.94 atomic percent addition of magnesium to pure aluminum...The contact angle was not affected by additions of lead, vanadium, manganese, chromium, and bismuth, whereas it was increased by additions of

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. [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.

  15. Determination of Stress-Corrosion Cracking in Aluminum-Lithium Alloy ML377

    NASA Technical Reports Server (NTRS)

    Valek, Bryan C.

    1995-01-01

    The use of aluminum-lithium alloys for aerospace applications is currently being studied at NASA Langley Research Center's Metallic Materials Branch. The alloys in question will operate under stress in a corrosive environment. These conditions are ideal for the phenomena of Stress-Corrosion Cracking (SCC) to occur. The test procedure for SCC calls for alternate immersion and breaking load tests. These tests were optimized for the lab equipment and materials available in the Light Alloy lab. Al-Li alloy ML377 specimens were then subjected to alternate immersion and breaking load tests to determine residual strength and resistance to SCC. Corrosion morphology and microstructure were examined under magnification. Data shows that ML377 is highly resistant to stress-corrosion cracking.

  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. Investigation of Cold Expansion of Short Edge Margin Holes with Pre-existing Cracks in 2024-T351 Aluminum Alloy

    DTIC Science & Technology

    2011-12-01

    INVESTIGATION OF COLD EXPANSION OF SHORT EDGE MARGIN HOLES WITH PREEXISTING CRACKS IN 2024-T351 ALUMINUM ALLOY by Dallen Lee...Aluminum Alloy 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Dallen Lee Andrew 5d. PROJECT NUMBER 5e. TASK NUMBER...SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF PAGES 207 19a. NAME OF RESPONSIBLE PERSON a. REPORT

  18. 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.

  19. Aluminum Alloys Reinforced by Nano-Particles Dispersion

    DTIC Science & Technology

    2010-03-01

    Jose Martin Herrera Ramirez Collaborator M. Sc. Ivanovich Estrada Guel Collaborator Eng. Wilber Antiinez Flores Collaborator Students: 1. Raul...Lucero, I. Estrada-Guel, D.C. Mendoza-Ruiz, M. Jose " Yacaman, Mechanical and Microstructural Characterization of Aluminum Reinforced with Carbon...9. Santos Beltran, V. Gallegos Orozco, F. Alvarado Hernandez, S. Haro Rodriguez, A. Lopez Ibarra and R. Martinez Sanchez. Synthesis and

  20. Corrosion Behavior of Friction Stir Welded High Strength Aluminum Alloys

    DTIC Science & Technology

    2002-01-18

    Angelo Guinasso, " Stress Corrosion Susceptibility in 7050 -T751 Aluminum Following Friction Stir Welding", Proc. First Friction Stir Welding Symposium...potential of the nugget. Susceptibility to stress corrosion cracking (SCC) was evaluated using the slow strain rate (SSR) method described in ASTM Standards...UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP015941 TITLE: Corrosion Behavior of Friction Stir Welded High Strength

  1. The Localized Corrosion of Aluminum Alloys - A Review.

    DTIC Science & Technology

    1983-07-01

    adsorption of, not only chloride ion, but other inorganic ions on oxide covered aluminum when immersed in aqueous electro- lytes has been definitely ...The binding energy was close to that of AlCl3 but the Author did not draw a definite conclusion with respect to the form in which the chlorine resided...analysis given in Table V was done spectrophotometrically with Eriochrome Cyanine R reagent (173) and only measured the monomeric species. It did not

  2. Component- and Alloy-Specific Modeling for Evaluating Aluminum Recycling Strategies for Vehicles

    NASA Astrophysics Data System (ADS)

    Modaresi, Roja; Løvik, Amund N.; Müller, Daniel B.

    2014-11-01

    Previous studies indicated that the availability of mixed shredded aluminum scrap from end-of-life vehicles (ELV) is likely to surpass the capacity of secondary castings to absorb this type of scrap, which could lead to a scrap surplus unless suitable interventions can be identified and implemented. However, there is a lack of studies analyzing potential solutions to this problem, among others, because of a lack of component- and alloy-specific information in the models. In this study, we developed a dynamic model of aluminum in the global vehicle stock (distinguishing 5 car segments, 14 components, and 7 alloy groups). The forecasts made up to the year 2050 for the demand for vehicle components and alloy groups, for the scrap supply from discarded vehicles, and for the effects of different ELV management options. Furthermore, we used a source-sink diagram to identify alloys that could potentially serve as alternative sinks for the growing scrap supply. Dismantling the relevant components could remove up to two-thirds of the aluminum from the ELV stream. However, the use of these components for alloy-specific recycling is currently limited because of the complex composition of components (mixed material design and applied joining techniques), as well as provisions that practically prevent the production of safety-relevant cast parts from scrap. In addition, dismantling is more difficult for components that are currently penetrating rapidly. Therefore, advanced alloy sorting seems to be a crucial step that needs to be developed over the coming years to avoid a future scrap surplus and prevent negative energy use and emission consequences.

  3. Neutron diffraction studies of welds of aerospace aluminum alloys

    SciTech Connect

    Martukanitz, R.P.; Howell, P.R.; Payzant, E.A.; Spooner, S.; Hubbard, C.R.

    1996-10-01

    Neutron diffraction and electron microscopy were done on residual stress in various regions comprising variable polarity plasma arc welds of alloys 2219 (Al-6.3Cu) and 2195 (Al-4.0Cu-1.0Li-0.5Mg-0.5Ag). Results indicate that lattice parameter changes in the various weld regions may be attributed to residual stresses generated during welding, as well as local changes in microstructure. Distribution of longitudinal and transverse stress of welded panels shows peaks of tension and compression, respectively, within the HAZ and corroborate earlier theoretical results. Position of these peaks are related to position of minimum strength within the HAZ, and the magnitude of these peaks are a fraction of the local yield strength in this region. Weldments of alloy 2195-T8 exhibited higher peak residual stress than alloy 2219-T87. Comparison of neutron diffraction and microstructural analysis indicate decreased lattice parameters associated with the solid solution of the near HAZ; this results in decreased apparent tensile residual stress within this region and may significantly alter interpretation of residual stress measurements of these alloys. Considerable relaxation of residual stress occurs during removal of specimens from welded panels and was used to aid in differentiating changes in lattice parameters attributed to residual stress from welding and modifications in microstructure.

  4. Micro and Nano Laser Pulses for Melting and Surface Alloying of Aluminum with Copper

    NASA Astrophysics Data System (ADS)

    Hamoudi, Walid K.; Ismail, Raid A.; Sultan, Fatima I.; Jaleel, Summayah

    2017-02-01

    In the present work, the use of microsecond and nanosecond laser pulses to alloy copper in aluminum is presented. In the first run, high purity (99.999%) copper thin film was thermally evaporated over (99.9%) purity, 300 μm aluminum sheet. Thereafter, surface alloying was performed using (1-3) 500 μs, (0.1-1.5) Joule Nd: YAG laser pulses; operating at 1060 nm wavelength. Hard homogeneous alloyed zone was obtained at depths between 60 and 110 μm below the surface. In the second run, 9 ns laser pulses from Q-switched Nd: YAG laser operating at 1060 nm was employed to melt/alloy Al-Cu sheets. The resulted alloyed depth, after using 20 laser pulses, was 199.22 μm for Al over Cu samples and 419.61 μm for Cu over Al samples. X-ray diffraction and fluorescence analysis revealed the formation of Cu2Al2, CuAl2 and δ- Al4Cu9 phases with percentage depended on laser energy and copper layer thicknesses.

  5. Design and Processing of Bimetallic Aluminum Alloys by Sequential Casting Technique

    NASA Astrophysics Data System (ADS)

    Karun, Akhil S.; Hari, S.; Ebhota, Williams S.; Rajan, T. P. D.; Pillai, U. T. S.; Pai, B. C.

    2017-01-01

    Sequential casting is a facile and fairly new technique to produce functionally graded materials (FGMs) and components by controlled mold filling process. In the present investigation, functionally graded bimetallic aluminum alloys are produced by sequential gravity casting using A390-A319 and A390-A6061 alloy combinations. The control in pouring time between two melts has shown a significant effect on the quality and nature of interface bonding. The microstructure reveals good interface miscibility achieved through diffusion bonding between the alloys. A higher hardness of 160 BHN in the A390 region is obtained in both sequential cast systems, and a minimum value of 105 and 91 BHN is observed in the A319 and A6061 regions, respectively. The tensile and compression strength for A390-A319 are 337 and 490 MPa, whereas for A390-A6061, they are 364 and 401 MPa, respectively, which are significantly higher compared with the standard values of the base alloys, which confirms strong interface bonding. The A390 region shows higher wear resistance compared with other regions of the sequential cast system. The process described in this study is a potential and efficient approach to create good bonding between two different aluminum alloys to develop advanced functional and structural materials.

  6. Cerium-Based, Intermetallic-Strengthened Aluminum Casting Alloy: High-Volume Co-product Development

    NASA Astrophysics Data System (ADS)

    Sims, Zachary C.; Weiss, D.; McCall, S. K.; McGuire, M. A.; Ott, R. T.; Geer, Tom; Rios, Orlando; Turchi, P. A. E.

    2016-07-01

    Several rare earth elements are considered by-products to rare earth mining efforts. By using one of these by-product elements in a high-volume application such as aluminum casting alloys, the supply of more valuable rare earths can be globally stabilized. Stabilizing the global rare earth market will decrease the long-term criticality of other rare earth elements. The low demand for Ce, the most abundant rare earth, contributes to the instability of rare earth extraction. In this article, we discuss a series of intermetallic-strengthened Al alloys that exhibit the potential for new high-volume use of Ce. The castability, structure, and mechanical properties of binary, ternary, and quaternary Al-Ce based alloys are discussed. We have determined Al-Ce based alloys to be highly castable across a broad range of compositions. Nanoscale intermetallics dominate the microstructure and are the theorized source of the high ductility. In addition, room-temperature physical properties appear to be competitive with existing aluminum alloys with extended high-temperature stability of the nanostructured intermetallic.

  7. Cerium-based, intermetallic-strengthened aluminum casting alloy: High-volume co-product development

    DOE PAGES

    Sims, Zachary C.; Weiss, David; McCall, S. K.; ...

    2016-05-23

    Here, several rare earth elements are considered by-products to rare earth mining efforts. By using one of these by-product elements in a high-volume application such as aluminum casting alloys, the supply of more valuable rare earths can be globally stabilized. Stabilizing the global rare earth market will decrease the long-term criticality of other rare earth elements. The low demand for Ce, the most abundant rare earth, contributes to the instability of rare earth extraction. In this article, we discuss a series of intermetallic-strengthened Al alloys that exhibit the potential for new high-volume use of Ce. The castability, structure, and mechanicalmore » properties of binary, ternary, and quaternary Al-Ce based alloys are discussed. We have determined Al-Ce based alloys to be highly castable across a broad range of compositions. Nanoscale intermetallics dominate the microstructure and are the theorized source of the high ductility. In addition, room-temperature physical properties appear to be competitive with existing aluminum alloys with extended high-temperature stability of the nanostructured intermetallic.« less

  8. Surface passivation of aluminum alloy 6061 with gaseous trichlorosilane: A surface investigation

    NASA Astrophysics Data System (ADS)

    Ngongang, Rickielle; Marceau, Eric; Carrier, Xavier; Pradier, Claire-Marie; Methivier, Christophe; Blanc, Jean-Luc; Carre, Martine

    2014-02-01

    A molecular-scale investigation of the interaction at room temperature between gaseous trichlorosilane (HSiCl3), used as a passivating agent, and surfaces of aluminum alloy AA6061 in a polished or hydroxylated state is conducted. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) provide information on the topography and morphology of AA6061 before and after hydroxylation and surface passivation, while surface chemistry has been investigated by Polarization Modulation Infrared Reflection-Absorption Spectroscopy (PM-IRRAS) and X-ray photoelectron spectroscopy (XPS). Oxidation and hydroxylation of the polished alloy surface in boiling water strongly modifies the roughness of the surface, with formation of platelets and needles of oxyhydroxide AlOOH. PM-IRRAS and XPS reveal that, upon adsorption, HSiCl3 dissociates and mainly forms HSiOHn(OAl)3-n, HSi(OSi)n(OAl)3-n and condensed HSiOx species, by reaction with sbnd OH groups from the AlOOH surface phase. The amount of deposited Si-containing species is larger on the rough surface of the hydroxylated alloy and this deposit is accompanied by a decrease of the amount of free sbnd OH groups evidenced by PM-IRRAS. These results can find applications in the field of functionalization of aluminum alloys. It is suggested that a homogeneous oxidation of the alloy surface prior to exposure to gaseous HSiCl3 may enhance the adsorption of the passivating agent.

  9. Spectro-photometric determinations of Mn, Fe and Cu in aluminum master alloys

    NASA Astrophysics Data System (ADS)

    Rehan; Naveed, A.; Shan, A.; Afzal, M.; Saleem, J.; Noshad, M. A.

    2016-08-01

    Highly reliable, fast and cost effective Spectro-photometric methods have been developed for the determination of Mn, Fe & Cu in aluminum master alloys, based on the development of calibration curves being prepared via laboratory standards. The calibration curves are designed so as to induce maximum sensitivity and minimum instrumental error (Mn 1mg/100ml-2mg/100ml, Fe 0.01mg/100ml-0.2mg/100ml and Cu 2mg/100ml-10mg/ 100ml). The developed Spectro-photometric methods produce accurate results while analyzing Mn, Fe and Cu in certified reference materials. Particularly, these methods are suitable for all types of Al-Mn, Al-Fe and Al-Cu master alloys (5%, 10%, 50% etc. master alloys).Moreover, the sampling practices suggested herein include a reasonable amount of analytical sample, which truly represent the whole lot of a particular master alloy. Successive dilution technique was utilized to meet the calibration curve range. Furthermore, the workout methods were also found suitable for the analysis of said elements in ordinary aluminum alloys. However, it was observed that Cush owed a considerable interference with Fe, the later one may not be accurately measured in the presence of Cu greater than 0.01 %.

  10. Cerium-based, intermetallic-strengthened aluminum casting alloy: High-volume co-product development

    SciTech Connect

    Sims, Zachary C.; Weiss, David; McCall, S. K.; McGuire, Michael A.; Ott, Ryan T.; Geer, Tom; Rios, Orlando; Turchi, P. A. E.

    2016-05-23

    Here, several rare earth elements are considered by-products to rare earth mining efforts. By using one of these by-product elements in a high-volume application such as aluminum casting alloys, the supply of more valuable rare earths can be globally stabilized. Stabilizing the global rare earth market will decrease the long-term criticality of other rare earth elements. The low demand for Ce, the most abundant rare earth, contributes to the instability of rare earth extraction. In this article, we discuss a series of intermetallic-strengthened Al alloys that exhibit the potential for new high-volume use of Ce. The castability, structure, and mechanical properties of binary, ternary, and quaternary Al-Ce based alloys are discussed. We have determined Al-Ce based alloys to be highly castable across a broad range of compositions. Nanoscale intermetallics dominate the microstructure and are the theorized source of the high ductility. In addition, room-temperature physical properties appear to be competitive with existing aluminum alloys with extended high-temperature stability of the nanostructured intermetallic.

  11. NASA-UVa light aerospace alloy and structures technology program supplement: Aluminum-based materials for high speed aircraft

    NASA Technical Reports Server (NTRS)

    Starke, E. A., Jr. (Editor)

    1995-01-01

    This report on the NASA-UVa light aerospace alloy and structure technology program supplement: Aluminum-Based Materials for High Speed Aircraft covers the period from July 1, 1992. The objective of the research is to develop aluminum alloys and aluminum matrix composites for the airframe which can efficiently perform in the HSCT environment for periods as long as 60,000 hours (certification for 120,000 hours) and, at the same time, meet the cost and weight requirements for an economically viable aircraft. Current industry baselines focus on flight at Mach 2.4. The research covers four major materials systems: (1) Ingot metallurgy 2XXX, 6XXX, and 8XXX alloys, (2) Powder metallurgy 2XXX alloys, (3) Rapidly solidified, dispersion strengthened Al-Fe-X alloys, and (4) Discontinuously reinforced metal matrix composites. There are ten major tasks in the program which also include evaluation and trade-off studies by Boeing and Douglas aircraft companies.

  12. Oxidation behavior in reaction-bonded aluminum-silicon alloy/alumina powder compacts

    SciTech Connect

    Yokota, S.H.

    1992-12-01

    Goal of this research is to determine the feasibility of producing low-shrinkage mullite/alumina composites by applying the reaction-bonded alumina (RBAO) process to an aluminum-silicon alloy/alumina system. Mirostructural and compositional changes during heat treatment were studied by removing samples from the furnace at different steps in the heating schedule and then using optical and scanning electron microscopy, EDS and XRD to characterize the powder compacts. Results suggest that the oxidation behavior of the alloy compact is different from the model proposed for the pure Al/alumina system.

  13. Specific features of sample preparation from amorphous aluminum alloys for transmission electron microscopy

    SciTech Connect

    Volkov, P. A.; Todorova, E. V.; Bakhteeva, N. D.; Ivanova, A. G.; Vasil'ev, A. L.

    2011-05-15

    An aluminum amorphous alloy doped with transition (Fe and Ni) and rare earth (La) metals has been used as an object of systematic study of the structural transformations that are characteristic of different methods of sample preparation for transmission electron microscopy (the mechanical tearing of ribbons, electrochemical thinning, and Ar{sup +}-ion etching under different conditions). The results of X-ray diffraction analysis and a calorimetric study of the structure in comparison with electron microscopy data made it possible to determine the optimal method of sample preparation, which ensures minimum distortions in the structure of metastable amorphous alloys with a low crystallization temperature.

  14. Thin Anodic Oxide Films on Aluminum Alloys and Their Role in the Durability of Adhesive Bonds.

    DTIC Science & Technology

    1980-02-01

    of each created interface B. Dynamic environment 1) stress 2) humidity and other atmospheric gases 3) temperature C. Failure analysis 1) fracture 2...fatigue 3) corrosion Studies involving the appropriate permutations and combina- tions of A, B, and C are needed to generate a data base for ad...is prominent ! -1 TABLE I NOMINAL CHEMICAL COMPOSITION OF ALUMINUM ALLOYS Alloy Si Cu Mn Mg Cr Zn Zr 2024 -- 4.5 0.6 1.5 ---- -- 7050 -- 2.3 -- 2.25

  15. 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.

  16. Method of Heat Treating Aluminum-Lithium Alloy to Improve Formability

    NASA Technical Reports Server (NTRS)

    Chen, Po-Shou (Inventor); Russell, Carolyn Kurgan (Inventor)

    2016-01-01

    A method is provided for heat treating aluminum-lithium alloys to improve their formability. The alloy is heated to a first temperature, maintained at the first temperature for a first time period, heated at the conclusion of the first time period to a second temperature, maintained at the second temperature for a second time period, actively cooled at the conclusion of the second time period to a third temperature, maintained at the third temperature for a third time period, and then passively cooled at the conclusion of the third time period to room temperature.

  17. Study of Processing and Microstructure of a Superplastic 5083 Aluminum Alloy

    DTIC Science & Technology

    2002-09-01

    AA5083 aluminum alloys designated lot numbers 978083 and 978901 were conducted at the Naval Postgraduate School in conjunction with mechanical testing...the ARCO materials and corresponding AA5083 materials, designated lot numbers 978083(A25) and 978901(A20), that were deformed under tensile...the OIM system were the AA5083 alloys deformed at 500ºC and 3x10-4s-1 and designated lot numbers 978083(A24) or 978901(A17). The procedure used to

  18. Part A - low-aluminum-content iron-aluminum alloys. Part B - commercial-scale melting and processing of FAPY alloy

    SciTech Connect

    Sikka, V.K.; Howell, C.R.; Hall, F.; Valykeo, J.

    1996-06-01

    The FAPY is a Fe-16 at. % Al alloy of nominal composition. The aluminum content of the alloy is such that it remains single phase ({alpha}) without the formation of an ordered phase (DO{sub 3}). The alloy has good oxidation resistance at temperatures up to 1000{degrees}C and has shown significantly superior performance as heating elements as compared to the commonly used nickel-based alloy, Nichrome. Although wire for the heating elements has been fabricated from small (15-1b) laboratory heats, for its commercial applications, the wire needs to be producible from large (1200 to 1500-1b) air-melted heats. The purpose of this study was to produce commercial size heats and investigate their mechanical properties and microstructure in the as-cast, hot-worked, and cold-worked conditions. The results of this study are expected to provide: (1) insight into processing steps for large heats into wire under commercial conditions, and (2) the mechanical properties data on commercial size heats in various product forms.

  19. 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.

  20. Effects of Chemistry and Processing on the Fracture Related Properties of P/M Alloy CT91.

    DTIC Science & Technology

    1985-08-01

    7075 ; again followed by softening in the 7075 -T6 alloy. Walker [108] attributed similar behavior to the formation of micro- cracking. Kuo [174] reports...conventional 7075 and Al-Zn-Mg ternaries shows regular hardening behavior . Benson and Hancock [170] report cyclic softening for 7075 -T651, but add that the...resembles the behavior of 7075 [174, 233], but is inferior to 7050 except in the high AK regime wIere toughness is a major factor [174]. McEvily [16

  1. Manufacturing a durable superhydrophobic polypropylene coating on aluminum alloy substrate by adding nano-titania nanoparticles.

    PubMed

    Jiang, Haiyun; Wu, Ruomei; Hu, Zhongliang; Yuan, Zhiqing; Zhao, Xuehui; Liu, Qilong

    2014-07-01

    A superhydrophobic polypropylene (PP) coating on the surface of aluminum alloy coupons is unstable because of the existence of metastable state in curing process. Nano-titania particles were added into PP solution to form hierarchical micro- and nano-structures of PP coatings on the surface of aluminum alloy coupons. The morphology of the coatings was observed with Scanning Electron Microscopy (SEM), and the corresponding structure and components were investigated with Energy Dispersive Spectrometer (EDS) and X-ray diffractometer (XRD), respectively. The results indicated that nano-TiO2 particles are the main nucleation cores in the curing of the coatings; PP in solution is enclosed in these cores and crystallizes gradually. The coatings can preserve the stable micro- and nano-structure on six months due to the nucleation action of nano-TiO2 particles, and its durable water contact angle (WCA) is about 164 +/- 1.5 degrees.

  2. 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.

  3. 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.

  4. Ultrasonic-promoted rapid TLP bonding of fine-grained 7034 high strength aluminum alloys.

    PubMed

    Guo, Weibing; Leng, Xuesong; Luan, Tianmin; Yan, Jiuchun; He, Jingshan

    2017-05-01

    High strength aluminum alloys are extremely sensitive to the thermal cycle of welding. An ultrasonic-promoted rapid TLP bonding with an interlayer of pure Zn was developed to join fine-grained 7034 aluminum alloys at the temperature of lower 400°C. The oxide film could be successfully removed with the ultrasonic vibration, and the Al-Zn eutectic liquid phase generated once Al and Zn contacted with each other. Longer ultrasonic time can promote the diffusion of Zn into the base metal, which would shorten the holding time to complete isothermal solidification. The joints with the full solid solution of α-Al can be realized with the ultrasonic action time of 60s and holding time of only 3min at 400°C, and the shear strength of joints could reach 223MPa. The joint formation mechanism and effects of ultrasounds were discussed in details.

  5. 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.

  6. Surface treatment of aluminum alloy at room temperature with titanium-nitride films by dynamic mixing

    NASA Astrophysics Data System (ADS)

    Sato, T.; Ohata, K.; Asahi, N.; Ono, Y.; Oka, Y.; Hashimoto, I.; Arimatsu, K.

    Titanium-nitride coating films were prepared on aluminum alloy plates at room temperature with simultaneous ion implantation and metal vapor deposition (dynamic mixing) by using a high current ion source. The films were analysed by means of Auger electron spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The results showed the presence of small amount of oxygen and carbon impurities due to a high current density (0.5-1.0 mA/cm 2) of the nitrogen beam (energy: 20 keV). Films of 1.2 μm thickness showed uniform composition. Titanium-nitride coated aluminum alloy (film thickness: 15 μm) was ten times harder than the untreated one. The coated plate was examined by a pin-on-disc wear tester. The results showed better wear properties.

  7. Integral Hot Gas Pressure Forming of an AA2219 Aluminum Alloy Ellipsoidal Shell

    NASA Astrophysics Data System (ADS)

    Yuan, S. J.; Zhang, R.; Zhang, W. W.

    2017-02-01

    To overcome the poor plastic deformation performance of AA2219 aluminum alloy sheet and its weld seam at room temperature, an integral hot gas pressure forming (IHGPF) process for a combined welded ellipsoidal shell was proposed. A simulation of the IHGPF process was conducted to analyze the axis length variation and thickness distribution during the forming process of the combined welded ellipsoidal shell at elevated temperature. The results demonstrated that lengths of the short and long axes were 150 mm and 220 mm, respectively, and that maximum wall thinning occurred at the pole. Furthermore, an experiment was conducted using IHGPF, and the forming accuracy was measured by three-dimensional video technology. A sound ellipsoidal shell with final axis length ratio of 1.5 was obtained with a shell diameter accuracy of more than 99.3%. It was experimentally proven that an aluminum alloy ellipsoidal shell can be formed using the proposed IHGPF technology.

  8. Effect of Fe on Microstructure and Properties of 8xxx Aluminum Conductor Alloys

    NASA Astrophysics Data System (ADS)

    Pan, Lei; Liu, Kun; Breton, Francis; -Grant Chen, X.

    2016-12-01

    The effect of Fe contents (0.3-0.7 wt.%) on the microstructure, electrical conductivity, mechanical and creep properties of 8xxx aluminum conductor alloys was investigated. Results revealed that the as-cast microstructure of 8xxx alloys was consisted of equiaxed α-Al grains and secondary Fe-rich intermetallics distributed in the interdendritic region. The extruded microstructure showed partially recrystallized structure for 0.3% Fe alloy but only dynamically recovered structures for 0.5 and 0.7% Fe alloys. With increasing Fe contents, the ultimate tensile strength and yield strength were remarkably improved, while the electrical conductivity was slightly decreased. Moreover, the creep resistance was greatly improved, which is attributed to the larger volume fraction of fine intermetallic particles and smaller subgrain size in the higher Fe-containing alloys. The creep threshold stress was found to increase from 24.6 to 33.9 MPa with increasing Fe contents from 0.3 to 0.7%, respectively. The true stress exponent values were close to 3 for all three experimental alloys, indicating that the creep mechanism of 8xxx alloys was controlled by dislocation glide.

  9. Stress Corrosion Cracking of Wrought and P/M High Strength Aluminum Alloys.

    DTIC Science & Technology

    1983-03-01

    M 1 Jan. 1982 - 31 Dec. 1982 High Strength Aluminum Alloys 6. PERFORMING ORG. REPORT NUMBER ,". A4THOR( s ) 0. CONTRACT OR GRANT NUMBER(&) F, W...program are presented, C-3 with emphasis on the stress corrosion cracking and hydrogen embrittlement of S the P/M X-7090 AValloy. More complete results...specimens. The value obtained, about 󈧋 cm / s -is one of the first successful measurements of this type. We remain confident that we have established

  10. Comparison of Mechanical and Constitutive Response for Five Aluminum Alloys for Armor Applications

    DTIC Science & Technology

    2010-06-27

    experimental data obtained for each alloy were used to determine constitutive constants for Johnson - Cook strength and failure models . The constitutive...extensive characterization effort was to develop the Johnson - Cook (J-C) constitutive model (including strength and failure) for the five aluminum (Al...effects are included in the Johnson - Cook constitutive model . The types of tests conducted include: smooth and notched tension at two different low

  11. Effect of Two-Stage Aging on Microstructure of 7075 Aluminum Alloys

    DTIC Science & Technology

    1981-04-01

    which particular microstructural characteristic is of greatest significance in the stress corrosion behavior of 7075 in a high strength condition. 2...is expected that RRA may provide less improvement in the stress corrosion behavior of 7050 than of I I 7075 . Data from these tests would allow...I v h EFFECT OF TWO-STAGE AGING ON MICROSTRUCTURE OF 7075 ALUMINUM ALLOYS RE- 627 "Final Report E April 1981 "by 7! Jonn M. Papazian OT i. Prepared

  12. Investigation of Fatigue Crack-Growth Resistance of Aluminum Alloys under Spectrum Loading.

    DTIC Science & Technology

    1983-04-01

    42 15 Longitudinal Microstructure of 7075 -T651 ..................... 43 16 Comparison of Fatigue Crack Growth Behavior Under Constant Amplitude...strength will exhibit similar retardation behavior . ( 2 0 ) Chanani(1) found that this was not the case for 2024-T8 and 7075 -T73 heat treated to the same...34 ASTM STP 595, 1976. 9. G.R. Chanani, "Effect of Thickness on Retardation Behavior of 7075 and 2024 Aluminum Alloys," ASTM STP 631, 1977. 10. G.R

  13. 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

  14. 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.

  15. Studies of the Crystallization Process of Aluminum-Silicon Alloys Using a High Temperature Microscope. Thesis

    NASA Technical Reports Server (NTRS)

    Justi, S.

    1985-01-01

    It is shown that primary silicon crystals grow polyhedral in super-eutectic AlSi melts and that phosphorus additives to the melt confirm the strong seeding capacity. Primary silicon exhibits strong dendritic seeding effects in eutectic silicon phases of various silicon alloys, whereas primary aluminum does not possess this capacity. Sodium addition also produces a dendritic silicon network growth in the interior of the sample that is attributed to the slower silicon diffusion velocity during cooling.

  16. 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.

  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. 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.

  19. Torsion Tests of 24S-T Aluminum-alloy Noncircular Bar and Tubing

    NASA Technical Reports Server (NTRS)

    Moore, R L; Paul, D A

    1943-01-01

    Tests of 24S-T aluminum alloy have been made to determine the yield and ultimate strengths in torsion of noncircular bar and tubing. An approximate basis for predicting these torsional strength characteristics has been indicated. The results show that the torsional stiffness and maximum shearing stresses within the elastic range may be computed quite closely by means of existing formulas based on mathematical analysis and the membrane analogy.

  20. NDT of Grain Boundaries in Microcrystalline Aluminum Alloy Using Methods of Nonlinear Acoustics

    SciTech Connect

    Korobov, Alexander I.; Mekhedov, Dmitry M.; Izosimova, Maria Y.

    2008-06-24

    The research of grain boundary influence on nonlinear elastic properties of aluminum alloy was carried out. It has been found that starting with certain threshold value of static tensile deformation, sharp increase of nonlinear acoustic parameter occurred. Compression deformation hasn't effect significantly on nonlinear elastic properties of polycrystal. On the basis of experimental data, distribution function of deformation on grain boundaries was calculated.

  1. Effect of Chromate and Chromate-Free Organic Coatings on Corrosion Fatigue of an Aluminum Alloy

    DTIC Science & Technology

    2012-02-20

    fatigue life [18]. In order to understand the mechanism of corrosion and corrosion fatigue of aluminum copper alloys, the morphological ...Microscopic features of fracture morphology were analyzed with scanning electron microscopy. In order to study the inhibition of these pigments...Conservation: Environmental Test Box Studies, European Cultural Heritage Newsletter on Research N2 (1988) 13–21. 63. G.O. Ilevbare, J.R. Scully, J

  2. 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.

  3. 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.

  4. High-speed mass-transport phenomena during carburization of aluminum alloy by laser plasma treatment

    NASA Astrophysics Data System (ADS)

    Fariaut, F.; Boulmer-Leborgne, C.; Semmar, N.; Le Menn, E.

    2006-04-01

    In the excimer laser carburizing process reported here, aluminum alloy samples have been treated in a propylene atmosphere, producing aluminum carbide surface layers. The layers have been characterized by nuclear reaction analysis that has shown carbon incorporation. X-ray diffraction at grazing incidence has evidenced aluminum carbide (Al4C3) phase. This study helps the understanding of the incorporation mechanisms of carbon in a surface. A micro-thermocapillary effect induced by heterogeneous surface formation has been evidenced. This original mass-transport phenomenon is very efficient in improving the carbon incorporation yield and hence in obtaining carbide layers several μm in thickness with a reduced laser pulse number. In order to obtain this micro-thermocapillary effect, the binary diagram of ceramic compounds must contain a peritectic.

  5. Studies on separation and purification of fission (99)Mo from neutron activated uranium aluminum alloy.

    PubMed

    Rao, Ankita; Kumar Sharma, Abhishek; Kumar, Pradeep; Charyulu, M M; Tomar, B S; Ramakumar, K L

    2014-07-01

    A new method has been developed for separation and purification of fission (99)Mo from neutron activated uranium-aluminum alloy. Alkali dissolution of the irradiated target (100mg) results in aluminum along with (99)Mo and a few fission products passing into solution, while most of the fission products, activation products and uranium remain undissolved. Subsequent purification steps involve precipitation of aluminum as Al(OH)3, iodine as AgI/AgIO3 and molybdenum as Mo-α-benzoin oxime. Ruthenium is separated by volatilization as RuO4 and final purification of (99)Mo was carried out using anion exchange method. The radiochemical yield of fission (99)Mo was found to be >80% and the purity of the product was in conformity with the international pharmacopoeia standards.

  6. Effect of Current Pathways During Spark Plasma Sintering of an Aluminum Alloy Powder

    NASA Astrophysics Data System (ADS)

    Kellogg, Frank; McWilliams, Brandon; Cho, Kyu

    2016-12-01

    Spark plasma sintering has been a well-studied processing technique primarily for its very high cooling and heating rates. However, the underlying phenomenon driving the sintering behavior of powders under an electric field is still poorly understood. In this study, we look at the effect of changing current pathways through the powder bed by changing die materials, from conductive graphite to insulating boron nitride for sintering aluminum alloy 5083 powder. We found that the aluminum powder itself was insulating and that by changing the current paths, we had to find alternate processing methods to initiate sintering. Altering the current pathways led to faster temperature raises and faster melting (and potentially densification) of the aluminum powder. A flash sintering effect in metallic powders is observed in which the powder compact undergoes a rapid transition from electrically insulating to conducting at a temperature of 583 K (310 °C).

  7. 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.

  8. Roles of Alloy Composition and Grain Refinement on Hot Tearing Susceptibility of 7××× Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Bai, Q. L.; Li, Y.; Li, H. X.; Du, Q.; Zhang, J. S.; Zhuang, L. Z.

    2016-08-01

    During the production of high-strength 7××× aluminum alloys, hot tearing has set up serious obstacles for attaining a sound billet/slab. In this research, some typical 7××× alloys were studied using constrained rod casting together with the measurement of thermal contraction and load development in the freezing range, aiming at investigating their hot tearing susceptibility. The results showed that the hot tearing susceptibility of an alloy depends not only on the thermal contraction in freezing range, which can decide the accumulated thermal strain during solidification, but also on the amount of nonequilibrium eutectics, which can effectively accommodate the thermally induced deformation. Our investigations reveal that Zn content has very profound effect on hot tearing susceptibility. The Zn/Mg ratio of the alloys also plays a remarkable role though it is not as pronounced as Zn content. The effect of Zn/Mg ratio is mainly associated with the amount of nonequilibrium eutectics. Grain refinement will considerably reduce the hot tearing susceptibility. However, excessive addition of grain refiner may promote hot tearing susceptibility of semi-solid alloy due to deteriorated permeability which is very likely to be caused by the heavy grain refinement and the formation of more intermetallic phases.

  9. Aluminum Alloys for ALS Cryogenic Tanks: Oxygen Compatibility. Volume 2

    DTIC Science & Technology

    1990-09-01

    Absorbed energy, calculated from specimen deformation characteristics, vs. absorbed energy, calculated from rebound heights. 79. 11.7.2. Tensile...combustion tests. Therefore, within the ability of the current tests to discern relative compatibility and flamability with LOX and COX, the Al-Li alloys and...each second phase particle measured and assuming a circular shape to calculate a diameter; (4) separating second phase particles into 10 bins based on

  10. Mechanical Property Evaluation of Aluminum Alloy 7010-T73651

    DTIC Science & Technology

    1980-07-01

    is intended to improve stress corrosion cracking resistance. Except for a slightly higher copper content, the two alloys, 7010 and 7050 , are similar...sensitive; the room temperature threshold for stress corrosion cracking in a 3.5% Wt. NaCl solution was determined to be in excess of 70 percent of the...Orientation Tensile Tests 4 3 Compact Type Specimen Configurations Used for Fracture Toughness (KIC), Threshold for Stress Corrosion Cracking (KISCC

  11. Chemical interactions and thermodynamic studies in aluminum alloy/molten salt systems

    NASA Astrophysics Data System (ADS)

    Narayanan, Ramesh

    The recycling of aluminum and aluminum alloys such as Used Beverage Container (UBC) is done under a cover of molten salt flux based on (NaCl-KCl+fluorides). The reactions of aluminum alloys with molten salt fluxes have been investigated. Thermodynamic calculations are performed in the alloy/salt flux systems which allow quantitative predictions of the equilibrium compositions. There is preferential reaction of Mg in Al-Mg alloy with molten salt fluxes, especially those containing fluorides like NaF. An exchange reaction between Al-Mg alloy and molten salt flux has been demonstrated. Mg from the Al-Mg alloy transfers into the salt flux while Na from the salt flux transfers into the metal. Thermodynamic calculations indicated that the amount of Na in metal increases as the Mg content in alloy and/or NaF content in the reacting flux increases. This is an important point because small amounts of Na have a detrimental effect on the mechanical properties of the Al-Mg alloy. The reactions of Al alloys with molten salt fluxes result in the formation of bluish purple colored "streamers". It was established that the streamer is liquid alkali metal (Na and K in the case of NaCl-KCl-NaF systems) dissipating into the melt. The melts in which such streamers were observed are identified. The metal losses occurring due to reactions have been quantified, both by thermodynamic calculations and experimentally. A computer program has been developed to calculate ternary phase diagrams in molten salt systems from the constituting binary phase diagrams, based on a regular solution model. The extent of deviation of the binary systems from regular solution has been quantified. The systems investigated in which good agreement was found between the calculated and experimental phase diagrams included NaF-KF-LiF, NaCl-NaF-NaI and KNOsb3-TINOsb3-LiNOsb3. Furthermore, an insight has been provided on the interrelationship between the regular solution parameters and the topology of the phase

  12. Coating of 6028 Aluminum Alloy Using Aluminum Piston Alloy and Al-Si Alloy-Based Nanocomposites Produced by the Addition of Al-Ti5-B1 to the Matrix Melt

    NASA Astrophysics Data System (ADS)

    El-Labban, Hashem F.; Abdelaziz, M.; Mahmoud, Essam R. I.

    2014-10-01

    The Al-12 pctSi alloy and aluminum-based composites reinforced with TiB2 and Al3Ti intermetallics exhibit good wear resistance, strength-to-weight ratio, and strength-to-cost ratio when compared to equivalent other commercial Al alloys, which make them good candidates as coating materials. In this study, structural AA 6028 alloy is used as the base material. Four different coating materials were used. The first one is Al-Si alloy that has Si content near eutectic composition. The second, third, and fourth ones are Al-6 pctSi-based reinforced with TiB2 and Al3Ti nano-particles produced by addition of Al-Ti5-B1 master alloy with different weight percentages (1, 2, and 3 pct). The coating treatment was carried out with the aid of GTAW process. The microstructures of the base and coated materials were investigated using optical microscope and scanning electron microscope equipped with EDX analyzer. Microhardness of the base material and the coated layer were evaluated using a microhardness tester. GTAW process results in almost sound coated layer on 6028 aluminum alloy with the used four coating materials. The coating materials of Al-12 pct Si alloy resulted in very fine dendritic Al-Si eutectic structure. The interface between the coated layer and the base metal was very clean. The coated layer was almost free from porosities or other defects. The coating materials of Al-6 pct Si-based mixed with Al-Ti5-B1 master alloy with different percentages (1, 2, and 3 pct), results in coated layer consisted of matrix of fine dendrite eutectic morphology structure inside α-Al grains. Many fine in situ TiAl3 and TiB2 intermetallics were precipitated almost at the grain boundary of α-Al grains. The amounts of these precipitates are increased by increasing the addition of Al-Ti5-B1 master alloy. The surface hardness of the 6028 aluminum alloy base metal was improved with the entire four used surface coating materials. The improvement reached to about 85 pct by the first type of

  13. Cast aluminum alloys containing dispersions of zircon particles

    NASA Astrophysics Data System (ADS)

    Banerji, A.; Surappa, M. K.; Rohatgi, P. K.

    1983-06-01

    A process for preparing Al-alloy castings containing dispersions of zircon particles is described. Composites were prepared by stirring zircon particles (40 to 200 µm size) in commercially pure Al (99.5 pct)* and Al-11.8 pct Si melts and subsequently casting these melts in permanent molds. It was found to be necessary to alloy the above two melts with 3 pct Mg to disperse substantial amounts of zircon particles (25 to 30 pct). Further, it was possible to disperse up to 60 wt pct zircon by adding up to 5 pct Mg; however, the melts containing above 30 wt pct zircon showed insufficient fluidity for gravity diecasting and had to be pressure diecast. Microstructural studies of cast composites indicated the presence of a reaction zone at the periphery of zircon particles, and electron probe microanalysis showed concentrations of Mg and Si at the particle-matrix interface. Hardness, abrasive wear resistance, elastic modulus, 0.2 pct proof stress, and tensile strength of cast Al-3 pct Mg alloy were found to improve with the dispersions of zircon particles. Scanning electron micrographs of abraded and fractured surfaces did not show any evidence of particle pull-outs or voids at the particle matrix interface, indicating strong continuous bonding.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

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

  16. Spray-coating of superhydrophobic aluminum alloys with enhanced mechanical robustness.

    PubMed

    Zhang, Youfa; Ge, Dengteng; Yang, Shu

    2014-06-01

    A superhydrophobic aluminum alloy was prepared by one-step spray coating of an alcohol solution consisting of hydrophobic silica nanoparticles (15-40 nm) and methyl silicate precursor on etched aluminum alloy with pitted morphology. The as-sprayed metal surface showed a water contact angle of 155° and a roll-off angle of 4°. The coating was subjected to repeated mechanical tests, including high-pressure water jetting, sand particles impacting, and sandpaper shear abrasion. It remained superhydrophobic with a roll-off angle <10° up to three cycles of water jetting (25 kPa for 10 min) and sand particle impinging. After five cycles, the roll-off angle increased, but no more than 19° while the water contact angle remained greater than 150°. The superhydrophobic state was also maintained after three cycles of sandpaper abrasion. It was found that the micro-protrusion structures on the etched aluminum alloy played an important role to enhance the coating mechanical robustness, where the nanoparticles could grab on the rough surface, specifically in the groove structures, in comparison with the smooth glass substrates spray coated with the same materials. Further, we showed that the superhydrophobicity could be restored by spray a new cycle of the nanocomposite solution on the damaged surface.

  17. 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).

  18. Ultrasonic method to determine gas porosity in aluminum alloy castings: Theory and experiment

    SciTech Connect

    Adler, L.; Rose, J.H.; Mobley, C.

    1986-01-15

    The characterization of porosity in solids using the frequency dependence of the ultrasonic attenuation is discussed both from the theoretical and experimental viewpoint. The major thrust of our work is the determination of the volume fraction and size of the voids for the case of dilute porosity (<6%) in structural materials. An aluminum alloy (A357) was chosen for study due to its economic importance in large-scale casting and the particular suitability of aluminum for this type of study. Following recent papers the attenuation is described by an independent scatterer model for spherical voids. Numerical results are presented in a form suitable for use with a range of materials. A method for determining the volume fraction and pore size is given. Specific tabular results are given for stainless steel, IN-100, Ti, Si3N4, as well as aluminum. Figures of merit which partially describe those situations in which the method is usable are also presented. In the experimental work a digitized spectrum analysis system was used to measure the frequency dependence of the attenuation coefficient in A357 aluminum cast alloys. In the cast materials the average pore size was in the order of 100 m and the pore concentration varied from essentially 0 to 6%. It was found that experimental measurement of the attenuation could be fit by the theoretical model. The resulting parameters yield a good estimate of the pore volume fraction.

  19. Ultrasonic method to determine gas porosity in aluminum alloy castings: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Adler, Laszlo; Rose, James H.; Mobley, Carroll

    1986-01-01

    The characterization of porosity in solids using the frequency dependence of the ultrasonic attenuation is discussed both from the theoretical and experimental viewpoint. The major thrust of our work is the determination of the volume fraction and size of the voids for the case of dilute porosity (<6%) in structural materials. An aluminum alloy (A357) was chosen for study due to its economic importance in large-scale casting and the particular suitability of aluminum for this type of study. Following recent papers the attenuation is described by an independent scatterer model for spherical voids. Numerical results are presented in a form suitable for use with a range of materials. A method for determining the volume fraction and pore size is given. Specific tabular results are given for stainless steel, IN-100, Ti, Si3N4, as well as aluminum. Figures of merit which partially describe those situations in which the method is usable are also presented. In the experimental work a digitized spectrum analysis system was used to measure the frequency dependence of the attenuation coefficient in A357 aluminum cast alloys. In the cast materials the average pore size was in the order of 100 μm and the pore concentration varied from essentially 0 to 6%. It was found that experimental measurement of the attenuation could be fit by the theoretical model. The resulting parameters yield a good estimate of the pore volume fraction.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  1. 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.

  2. Electrochemical characteristics of a carbon fibre composite and the associated galvanic effects with aluminium alloys

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Curioni, M.; Jamshidi, P.; Walker, A.; Prengnell, P.; Thompson, G. E.; Skeldon, P.

    2014-09-01

    The electrochemical behaviour of a carbon fibre reinforced epoxy matrix composite in 3.5% NaCl and 3.5% NaCl + 0.5 M CuSO4 electrolytes was examined by potentiodynamic polarisation, potentiostatic polarisation and scanning electron microscopy. Exposed carbon fibres on two defined regions (“front” and “side”) are a focus of the investigation. The large size of the exposed carbon fibres on the side region is responsible for a higher cathodic current density than the front region in the NaCl electrolyte. The deposition of copper on the front surface of composite confirmed that the significantly higher cathodic current resulted from the exposure of the fibres to the NaCl electrolyte. Galvanic coupling between the composite and individual aluminium alloys (AA7075-T6 and AA1050) was used to measure galvanic potentials and galvanic current densities. The highly alloyed AA7075-T6 alloy and its high population density of cathodic sites compared to the AA1050 acted to reduce the galvanic effect when coupled to the composite front or side regions.

  3. Chemical effects in the Corrosion of Aluminum and Aluminum Alloys. A Bibliography

    DTIC Science & Technology

    1976-10-01

    exposure trial on 52 structural metals and alloys in 5 uncontaminat":d natural environments. A 1969-35 N. Subramanyan and A.R. Yamuna Brit. Corros. J., 4...Reduction of corrosion rate of Al cladding on fuel elements in Savannah River reactors by lithium silicate. 1970-30 B.A. Pandya, S.S. Sampat, J.C. Vora

  4. Production of Magnesium and Aluminum-Magnesium Alloys from Recycled Secondary Aluminum Scrap Melts

    NASA Astrophysics Data System (ADS)

    Gesing, Adam J.; Das, Subodh K.; Loutfy, Raouf O.

    2016-02-01

    An experimental proof of concept was demonstrated for a patent-pending and trademark-pending RE12™ process for extracting a desired amount of Mg from recycled scrap secondary Al melts. Mg was extracted by electrorefining, producing a Mg product suitable as a Mg alloying hardener additive to primary-grade Al alloys. This efficient electrorefining process operates at high current efficiency, high Mg recovery and low energy consumption. The Mg electrorefining product can meet all the impurity specifications with subsequent melt treatment for removing alkali contaminants. All technical results obtained in the RE12™ project indicate that the electrorefining process for extraction of Mg from Al melt is technically feasible. A techno-economic analysis indicates high potential profitability for applications in Al foundry alloys as well as beverage—can and automotive—sheet alloys. The combination of technical feasibility and potential market profitability completes a successful proof of concept. This economical, environmentally-friendly and chlorine-free RE12™ process could be disruptive and transformational for the Mg production industry by enabling the recycling of 30,000 tonnes of primary-quality Mg annually.

  5. Nondestructive detection of an undesirable metallic phase, T.sub.1, during processing of aluminum-lithium alloys

    DOEpatents

    Buck, Otto; Bracci, David J.; Jiles, David C.; Brasche, Lisa J. H.; Shield, Jeffrey E.; Chumbley, Leonard S.

    1990-08-07

    A method is disclosed for detecting the T.sub.1 phase in aluminum-lithium alloys through simultaneous measurement of conductivity and hardness. In employing eddy current to measure conductivity, when the eddy current decreases with aging of the alloy, while the hardness of the material continues to increase, the presence of the T.sub.1 phase may be detected.

  6. Aging Optimization of Aluminum-Lithium Alloy C458 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H.; Farahmand, B.; Rioja, R.

    2003-01-01

    Compared with aluminum alloys such as 2219, which is widely used in space vehicle for cryogenic tanks and unpressurized structures, aluminum-lithium alloys possess attractive combinations of lower density and higher modulus along with comparable mechanical properties. These characteristics have resulted in the successful use of the aluminum-lithium alloy 2195 (Al-1.0 Li-4.0 Cu-0.4 Mg-0.4 Ag-0.12 Zr) for the Space Shuttle External Tank, and the consideration of newer U.S. aluminum-lithium alloys such as L277 and C458 for future space vehicles. These newer alloys generally have lithium content less than 2 wt. % and their composition and processing have been carefully tailored to increase the toughness and reduce the mechanical property anisotropy of the earlier generation alloys such 2090 and 8090. Alloy processing, particularly the aging treatment, has a significant influence on the strength-toughness combinations and their dependence on service environments for aluminum-lithium alloys. Work at NASA Marshall Space Flight Center on alloy 2195 has shown that the cryogenic toughness can be improved by employing a two-step aging process. This is accomplished by aging at a lower temperature in the first step to suppress nucleation of the strengthening precipitate at sub-grain boundaries while promoting nucleation in the interior of the grains. Second step aging at the normal aging temperature results in precipitate growth to the optimum size. A design of experiments aging study was conducted for plate. To achieve the T8 temper, Alloy C458 (Al-1.8 Li-2.7 Cu-0.3 Mg-0.08 Zr-0.3 Mn-0.6 Zn) is typically aged at 300F for 24hours. In this study, a two-step aging treatment was developed through a comprehensive 2(exp 4) full factorial design of experiments study and the typical one-step aging used as a reference. Based on the higher lithium content of C458 compared with 2195, the first step aging temperature was varied between 175F and 250F. The second step aging temperatures was

  7. Extended Performance Assessment in Accelerated Corrosion and Adhesion of CARC Prepared Aluminum Alloy 5059-H131 for Three Different Pretreatment Methods

    DTIC Science & Technology

    2008-03-01

    9540P Cyclic Accelerated Corrosion Analysis of Nonchromate Conversion Coatings on Aluminum Alloys 2024, 2219 , 5083, and 7075 Using DoD Paint Systems...PERFORMANCE ASSESSMENT IN ACCELERATED CORROSION AND ADHESION OF CARC PREPARED ALUMINUM ALLOY 5059-H131 FOR THREE DIFFERENT PRETREATMENT METHODS Brian E...whether or not the alloy differences will warrant modifications to current pretreatment processes. Keywords: Corrosion , Aluminum , 5059-H131, Cyclic

  8. General Corrosion Resistance Comparisons of Medium- and High-Strength Aluminum Alloys for DOD Systems Using Laboratory-Based Accelerated Corrosion Methods

    DTIC Science & Technology

    2009-09-01

    General Corrosion Resistance Comparisons of Medium- and High-Strength Aluminum Alloys for DOD Systems Using Laboratory-Based Accelerated... Aluminum Alloys for DOD Systems Using Laboratory-Based Accelerated Corrosion Methods Brian E. Placzankis Weapons and Materials Research Directorate...March 2006–October 2008 4. TITLE AND SUBTITLE General Corrosion Resistance Comparisons of Medium- and High-Strength Aluminum Alloys for DOD

  9. Aluminum-Silicon Alloy Having Improved Properties at Elevated Temperatures and Articles Cast Therefrom

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    An aluminum alloy suitable for high temperature applications, such as heavy duty pistons and other internal combustion applications. having the following composition, by weight percent (wt %): Silicon: 11.0-14.0; Copper: 5.6-8.0; Iron: 0-0.8; Magnesium: 0.5-1.5; Nickel: 0.05-0.9; Manganese: 0.5-1.5; Titanium: 0.05-1.2; Zirconium: 0.12-1.2; Vanadium: 0.05-1.2; Zinc: 0.005-0.9; Strontium: 0.001-0.1; Aluminum: balance. In this alloy the ratio of silicon:magnesium is 10-25, and the ratio of copper:magnesium is 4-15. After an article is cast from this alloy, the article is treated in a solutionizing step which dissolves unwanted precipitates and reduces any segregation present in the original alloy. After this solutionizing step, the article is quenched, and is then aged at an elevated temperature for maximum strength.

  10. Mechanical behavior of aluminum-bearing ferritic alloys for accident-tolerant fuel cladding applications

    NASA Astrophysics Data System (ADS)

    Guria, Ankan

    Nuclear power currently provides about 13% of electrical power worldwide. Nuclear reactors generating this power traditionally use Zirconium (Zr) based alloys as the fuel cladding material. Exothermic reaction of Zr with steam under accident conditions may lead to production of hydrogen with the possibility of catastrophic consequences. Following the Fukushima-Daiichi incident, the exploration of accident-tolerant fuel cladding materials accelerated. Aluminum-rich (around 5 wt. %) ferritic steels such as Fecralloy, APMT(TM) and APM(TM) are considered as potential materials for accident-tolerant fuel cladding applications. These materials create an aluminum-based oxide scale protecting the alloy at elevated temperatures. Tensile deformation behavior of the above alloys was studied at different temperatures (25-500 °C) at a strain rate of 10-3 s-1 and correlated with microstructural characteristics. Higher strength and decent ductility of APMT(TM) led to further investigation of the alloy at various combination of strain rates and temperatures followed by fractography and detailed microscopic analyses. Serrations appeared in the stress-strain curves of APMT(TM) and Fecralloy steel tested in a limited temperature range (250-400 °C). The appearance of serrations is explained on the basis of dynamic strain aging (DSA) effect due to solute-dislocation interactions. The research in this study is being performed using the funds received from the US DOE Office of Nuclear Energy's Nuclear Energy University Programs (NEUP).

  11. Centrifugal Casting Features/Metallurgical Characterization of Aluminum Alloys

    SciTech Connect

    Chirita, G.; Soares, D.; Cruz, D.; Silva, F. S.; Stefanescu, I.

    2008-02-15

    This paper deals with the study of centrifugal effects on aluminium castings under high G values. Most of the studies in this domain (FGMs obtained by centrifugal casting) deal with functionally graded composites reinforced with a solid phase such as silicon particles or others. However, in this study it will be shown that unreinforced aluminium alloys may be significantly influenced by the centrifugal effect and that functionally graded castings are also obtained. It has been observed that the centrifugal effect may increase in some alloys, depending on the relative position in the castings, the rupture strength by approx. 50%, and rupture strain by about 300%, as compared to the gravity casting technique. The Young's modulus may also increase by about 20%. It has also been reported that in vertical centrifugal castings there are mainly three aspects that affect the components thus obtained, namely: fluid dynamics; vibration (inherent to the system); and centrifugal force. These features have a different effect on the castings depending on the aluminium alloy. In this paper, an analysis of the most important effects of the centrifugal casting process on metallurgical features is conducted. A solidification characterization at several points along the mould will be made in order to have an accurate idea of both the fluid dynamics inside the mould during the casting and the solidification behavior in different parts of the component. These two analyses will be related to the metallurgical properties (phase distribution; SDAS; eutectic silicon content and shape, pores density and shape) along the component and mainly along the direction of the centrifugal pressure. A comparison between castings obtained by both centrifugal casting technique and gravity casting technique is made for reference (gravity casting)

  12. Processing and properties of low-aluminum alloy FAPY

    SciTech Connect

    Sikka, V.K.; Howell, C.R.; Hall, F.; Valykeo, J.

    1996-07-01

    This paper deals with the melting, processing, properties, and microstructure of three commercially melted heats of Fe-16 at. % Al alloy FAPY. All of the heats were air-induction melted (AIM), two at Hoskins Manufacturing Company (Hamburg, Michigan) and one at United Defense (Anniston, Alabama). One ingot from each of the heats was used for testing at the Oak Ridge National Laboratory. A 127-mm.-long section from each ingot was used for determining properties and microstructure in the as-cast, cast and hot-processed, and cold-rolled conditions. The fine-grained sheet showed 20% elongation at room temperature.

  13. Feasibility of Cutting Aluminum Alloys with a 6-Kilowatt Laser

    DTIC Science & Technology

    1977-09-01

    requirements. However, it wa~s further shown that it is not feasible to use an as-laser- cutI edge fcr hardware where machined edges or hole filling fasteners...Alloys Program II 10 Concentric Jet -Assist Configuration 14 I I Oft-Axis Jet -Assist Configuration 14 12 Needle Jet -Assist Configuration 14 13 Coaxial... Jet -Assist Configuration 14 14 Effect of Jet Configurations on Cut Characteristics 15 15 Effect of Gas on Cut Characteristics 16 16 Effect of Power

  14. Mold Materials For Permanent Molding of Aluminum Alloys

    SciTech Connect

    John F Wallace; David Schwam; Wen Hong dxs11@po.cwru.edu

    2001-09-14

    A test that involves immersion of the potential mod materials for permanent molds has been developed that provides a thermal cycle that is similar to the experienced during casting of aluminum in permanent molds. This test has been employed to determine the relative thermal fatigue resistance of several different types of mold materials. Four commercial mold coatings have been evaluated for their insulating ability, wear resistance and roughness. The results indicate that composition and structure of the mold materials have considerable effect on their thermal fatigue cracking behavior. Irons with a gray iron structure are the most prone to thermal fatigue cracking followed by compacted graphite irons with the least thermal fatigue cracking of the cast irons experienced by ductile iron. The composition of these various irons affects their behavior.

  15. FRICTION-STIR-LAP-WELDS OF AA6111 ALUMINUM ALLOY

    SciTech Connect

    Yadava, Manasij; Mishra, Rajiv S.; Chen, Y. L.; Gayden, X.; Grant, Glenn J.

    2007-01-09

    Lap joints of 1 mm thick AA6111 aluminum sheets were made by friction stir welding, using robotic and conventional machines. Welds were made for advancing as well as retreating side loading. Thinning in welds was quantified. Lap shear test of welds was conducted in as-welded and paint-baked conditions. Conventional machine welds showed less thinning and better strength than robotic machine welds. Process forces in conventional machine welding were higher. Paint bake treatment improved the weld strength; but the improvement varied with process parameters. Advancing side loaded welds achieved higher strength than the retreating side loaded welds. Fracture location was found to occur on the loaded side of the weld and along the thinning defect.

  16. 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.

  17. Character of melting and evaporation in laser beam welding of two aluminum alloys

    SciTech Connect

    Xijing, W.; Katayama, S.; Matsunawa, A.

    1997-02-01

    The phenomenon of evaporation within the keyhole during laser beam welding of aluminum Alloys A5052 and A5083 was investigated under different welding conditions. The character of the molten pool was compared and analyzed. It was found that the evaporation of the main alloying element for these alloys, magnesium, greatly influenced the reaction force induced between the metal vapor and thermal plasma, which in turn affected the degree of penetration. The results of these experiments also confirmed that increasing shielding gas flow rate, within a limit, and a light increase in the entrance angle of the laser beam improved meltability and increased penetration depth. Surface preparation was also observed to improve beam absorption and increase penetration.

  18. VAMAS tests of structural materials on aluminum alloy and composite material at cryogenic temperatures

    SciTech Connect

    Ogata, T.; Evans, D.

    1997-06-01

    A Technical Working Area 17, cryogenic structural materials, has been organized in the Versailles Project on Advanced Materials and Standards (VAMAS) to promote the prestandardization program on material properties tests of glass fiber reinforced polymer (GFRP) composite materials and alloys at liquid helium temperature. A series of international interlaboratory comparisons of both tensile and fracture toughness tests for aluminum alloy 2219 and compression and shear tests for composite material G-10CR were performed. Nine research institutes from seven nations have participated in this project. The results prove that there are few problems in cryogenic tensile tests for alloy materials. In compression and shear tests, the amount of data scatter was identified and further experiments are planned. This paper presents the program details and interim results of round robin tests.

  19. Mechanical Properties of Solid-State Recycled 4xxx Aluminum Alloy Chips

    NASA Astrophysics Data System (ADS)

    Tokarski, Tomasz

    2016-08-01

    The direct production of aluminum from bauxite ores is known to be a very energetic-intensive operation compared to other metallurgical processes. Due to energy issues and the rapid increase in aluminum demand, new kinds of aluminum production processes are required. Aluminum waste recycling, which has an advantage of lowering the cost of electric power consumption, is considered to be an alternative route for material manufacturing. In this work, the way of reusing aluminum EN-AC 44000 alloy scraps by hot extrusion was presented. Metal chips of different sizes and morphology were cold compacted into billet form and then hot extruded. Mechanical properties investigations combined with microstructure observations were performed. Mechanical anisotropy behavior of material was evaluated on the base of tensile test experiments performed on samples machined at 0°, 45°, and 90°, respectively, to the extrusion direction. It was found that the initial size of the chips has an influence on the mechanical properties of the received profiles. Samples produced from fine chips revealed higher tensile strength in comparison to larger chips, which can be attributed to a refined microstructure containing fine, hard Si particles and Fe-rich intermetallic phases. Finally, it was found that anisotropic behavior of chip-based profiles is similar to conventionally cast and extruded materials which prove good bonding quality between chips.

  20. Aluminum Lithium Alloy 2195 Fusion Welding Improvements with New Filler Wire

    NASA Technical Reports Server (NTRS)

    Russell, Carolyn; Bjorkman, Gerry; McCool, Carolyn (Technical Monitor)

    2000-01-01

    A viewgraph presentation outlines NASA Marshall Space Flight Center, Lockheed Martin Michoud Space Systems, and McCook Metals' development an aluminum-copper weld filler wire for fusion welding 2195 aluminum lithium. The aluminum-copper based weld filler wire has been identified as B218, which is the result of six years of weld filler wire development funded by NASA, Lockheed Martin, and McCook Metals. The Super Lightweight External Tank for the NASA Space Shuttle Program consists of 2195 welded with 4043 aluminum-silicon weld filler wire. The B218 filler wire chemistry was developed to produce enhanced 2195 weld and repair weld mechanical properties. An initial characterization of the B218 weld filler wire was performed consisting of initial weld and repair weld evaluation comparing B218 and 4043. The testing involved room temperature and cryogenic tensile testing along with fracture toughness testing. B218 weld filler wire proved to produce enhanced initial and repair weld tensile and fracture properties over 4043. B218 weld filler wire has proved to be a superior weld filler wire for welding 2195 and other aluminum lithium alloys over 4043.

  1. Springback analysis on AA 6061 aluminum alloy sheets

    NASA Astrophysics Data System (ADS)

    Ramulu, Perumalla Janaki; Rao, P. Srinivasa; Yimer, Wassihun

    2016-10-01

    In automotive industry, sheet metal forming process play a key role with respect to economy and weight reduction ratio. In sheet metal forming, one of the operations is bending operation in which sheet will not go under sever deformation. The end components are made by applying the continuous load on the sheet in the bending process. In bending process, elastic limits of materials are exceeded, but flow limit thereof cannot be exceeded. Therefore, the material still keeps a portion of its original flexibility character. When the load is released, the material on forcing compress side tries to enlarge, whereas the material on tensile side tries to shrink. As a result, the material tries to spring back and the bended material by flexing slightly tries to open. Springback varies according to thickness of the material, material and process parameters, type of material, period when punch load stays on the material, dimensions of die, force applied, and bending radius. In order to make bending at a desired angle, springback amounts should be avoided. In the present work, experimentation on AA 6061 alloy sheet springback analysis has done with seven different rolling directions. Results are noted with respect to load, displacement, and die angle on the springback effect. It observed that springback affect is existed notably in the AA 6061 alloys with respect to die angle.

  2. Processing Studies of Aluminum-Magnesium and Aluminum-Copper-Lithium Alloys

    DTIC Science & Technology

    1990-03-01

    mechanisim of microstructural refinement during processing. Most recently, Gorsuch has investigated the effects of varying the annealing time between...obtained during testing at 300°C [Ref 3]. A portion of this research will follow that of Gorsuch by extending the annealing interval to 60 minutes in...on an Al.10Mg.0.lZr(wt.pct) alloy wherein Gorsuch varied the annealing times between rolling passes. As the annealing times are increased from 5

  3. Solute Enhanced Strain Hardening of Aluminum Alloys to Achieve Improved Combinations of Strength and Toughness

    NASA Astrophysics Data System (ADS)

    Hovanec, Christopher James

    2011-12-01

    The feasibility of achieving improved combinations of strength and toughness in aluminum alloy 2524 through solute enhanced strain hardening (SESH) has been explored in this study and shown to be viable. The effectiveness of SESH is directly dependent on the strain hardening rate (SHR) of the material being processed. Aluminum alloy 2524 naturally ages to the T4-temper after solution heat treating and quenching. The SHR of strain free and post cold rolled material as a function of natural aging time has been measured by means of simple compression. It has been determined that the SHR of AA2524 is more effective with solute in solution rather than clustered into GP zones. It has also been shown that the typical rapid formation of GP zones at room temperature (natural aging) is inhibited by moderate cold rolling strains (□CR ≥ 0.2) through dislocation aided vacancy annihilation. The practical limitations of quenching rate have been determined using hardness and eddy current electrical conductivity measurements. It has been shown that too slow of a quench rate results in solute being lost to both the formation of GP zones and embrittling precipitates during the quench, while too rapid of a quench rate results in mid-plane cracking of the work piece during the SESH processing. The mid-plane cracking was overcome by using an uphill quenching procedure to relieve residual stresses within the work piece. Aluminum alloy 2524 strengthened through SESH to a yield strength 11% greater than that in the T6-Temper exhibits: equivalent toughness, 5% greater UTS, 1% greater elongation, 7% greater R.A., and absorbs 15% more energy during tensile testing. At yield strengths comparable to published data for 2x24 alloys, the SESH 2524 exhibited up to a 60% increase in fracture toughness. The fractured surfaces of the SESH material exhibited transgranular dimpled rupture as opposed to the grain boundary ductile fracture (GBPF) observed in the artificially aged material.

  4. Developing an Empirical Relationship to Predict Tensile Strength of Friction Stir Welded AA2219 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Elangovan, K.; Balasubramanian, V.; Babu, S.

    2008-12-01

    AA2219 aluminum alloy (Al-Cu-Mn alloy) has gathered wide acceptance in the fabrication of lightweight structures requiring a high strength-to-weight ratio and good corrosion resistance. Friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being welded does not melt and recast. This process uses a nonconsumable tool to generate frictional heat in the abutting surfaces. The welding parameters such as tool rotational speed, welding speed, axial force, etc., and tool pin profile play a major role in deciding the joint strength. An attempt has been made to develop an empirical relationship between FSW variables to predict tensile strength of the friction stir welded AA2219 aluminum alloy. To obtain the desired strength, it is essential to have a complete control over the relevant process parameters to maximize the tensile strength on which the quality of a weldment is based. Therefore, it is very important to select and control the welding process parameter for obtaining maximum strength. To achieve this various prediction methods such as response surface method (RSM), analysis of variance (ANOVA), Student’s t-test, coefficient of determination, etc., can be applied to define the desired output variables through developing mathematical models to specify the relationship between the output parameters and input variables. Four factors, five levels central composite design have been used to minimize number of experimental conditions. The developed mathematical relationship can be effectively used to predict the tensile strength of FSW joints of AA2219 aluminum alloy at 95% confidence level.

  5. Corrosion and corrosion fatigue of airframe aluminum alloys

    NASA Technical Reports Server (NTRS)

    Chen, G. S.; Gao, M.; Harlow, D. G.; Wei, R. P.

    1994-01-01

    Localized corrosion and corrosion fatigue crack nucleation and growth are recognized as degradation mechanisms that effect the durability and integrity of commercial transport aircraft. Mechanically based understanding is needed to aid the development of effective methodologies for assessing durability and integrity of airframe components. As a part of the methodology development, experiments on pitting corrosion, and on corrosion fatigue crack nucleation and early growth from these pits were conducted. Pitting was found to be associated with constituent particles in the alloys and pit growth often involved coalescence of individual particle-nucleated pits, both laterally and in depth. Fatigue cracks typically nucleated from one of the larger pits that formed by a cluster of particles. The size of pit at which fatigue crack nucleates is a function of stress level and fatigue loading frequency. The experimental results are summarized, and their implications on service performance and life prediction are discussed.

  6. Robust biomimetic-structural superhydrophobic surface on aluminum alloy.

    PubMed

    Li, Lingjie; Huang, Tao; Lei, Jinglei; He, Jianxin; Qu, Linfeng; Huang, Peiling; Zhou, Wei; Li, Nianbing; Pan, Fusheng

    2015-01-28

    The following facile approach has been developed to prepare a biomimetic-structural superhydrophobic surface with high stabilities and strong resistances on 2024 Al alloy that are robust to harsh environments. First, a simple hydrothermal treatment in a La(NO3)3 aqueous solution was used to fabricate ginkgo-leaf like nanostructures, resulting in a superhydrophilic surface on 2024 Al. Then a low-surface-energy compound, dodecafluoroheptyl-propyl-trimethoxylsilane (Actyflon-G502), was used to modify the superhydrophilic 2024 Al, changing the surface character from superhydrophilicity to superhydrophobicity. The water contact angle (WCA) of such a superhydrophobic surface reaches up to 160°, demonstrating excellent superhydrophobicity. Moreover, the as-prepared superhydrophobic surface shows high stabilities in air-storage, chemical and thermal environments, and has strong resistances to UV irradiation, corrosion, and abrasion. The WCAs of such a surface almost remain unchanged (160°) after storage in air for 80 days, exposure in 250 °C atmosphere for 24 h, and being exposed under UV irradiation for 24 h, are more than 144° whether in acidic or alkali medium, and are more than 150° after 48 h corrosion and after abrasion under 0.98 kPa for 1000 mm length. The remarkable durability of the as-prepared superhydrophobic surface can be attributed to its stable structure and composition, which are due to the existence of lanthanum (hydr)oxides in surface layer. The robustness of the as-prepared superhydrophobic surface to harsh environments will open their much wider applications. The fabricating approach for such robust superhydrophobic surface can be easily extended to other metals and alloys.

  7. Static Recovery Modeling of Dislocation Density in a Cold Rolled Clad Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Penlington, Alex

    Clad alloys feature one or more different alloys bonded to the outside of a core alloy, with non-equilibrium, interalloy interfaces. There is limited understanding of the recovery and recrystallization behaviour of cold rolled clad aluminum alloys. In order to optimize the properties of such alloys, new heat treatment processes may be required that differ from what is used for the monolithic alloys. This study examines the recovery behaviour of a cold rolled Novelis Fusion(TM) alloy containing an AA6XXX core with an AA3003 cladding on one side. The bond between alloys appears microscopically discrete and continuous, but has a 30 microm wide chemical gradient. The as-deformed structure at the interalloy region consists of pancaked sub-grains with dislocations at the misorientation boundaries and a lower density organized within the more open interiors. X-ray line broadening was used to extract the dislocation density from the interalloy region and an equivalently deformed AA6XXX following static annealing using a modified Williamson-Hall analysis. This analysis assumed that Gaussian broadening contributions in a pseudo-Voigt function corresponded only to strain from dislocations. The kinetics of the dislocation density evolution to recrystallization were studied isothermally at 2 minute intervals, and isochronally at 175 and 205°C. The data fit the Nes model, in which the interalloy region recovered faster than AA6XXX at 175°C, but was slower at 205°C. This was most likely caused by change in texture and chemistry within this region such as over-aging of AA6XXX . Simulation of a continuous annealing and self homogenization process both with and without pre-recovery indicates a detectable, though small change in the texture and grain size in the interalloy region.

  8. Microstructural Investigation of Friction-Stir-Welded 7005 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Xu, Xuesong; Lu, Yan; Zheng, Feiyan; Chen, Bin

    2015-11-01

    This paper is aimed to investigate the microstructure of 7005 aluminum sheets joined by friction-stir welding as well as their mechanical properties. Specimens with ten different sets of welding parameters were studied. Tensile test and fracture analysis determined that the joint of the best quality was obtained at the rotation speed of 1000 rpm matching with the travel speed of 200 mm/min, and the travel speed has more impact on the ultimate tensile strength. Optical microscope observation was applied to this high-quality specimen and gave evidence to explaining the formation of the onion ring structure. Electron back-scattered diffraction (EBSD) technique was employed to characterize the textures and revealed the evolution of microstructures during friction stir processing. The EBSD results showed that the grains maintain their original orientations at relatively low deformation while the orientations rotate under increasing strain. Accumulated rotation will turn the textures into mixed shear components, which finally results in grain refinement and contributes to the high quality of the joint.

  9. Physical Simulation Method for the Investigation of Weld Seam Formation During the Extrusion of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Fang, Gang; Nguyen, Duc-Thien; Zhou, Jie

    2016-12-01

    Extrusion through the porthole die is a predominant forming process used in the production of hollow aluminum alloy profiles across the aluminum extrusion industry. Longitudinal weld seams formed during the process may negatively influence the quality of extruded profiles. It is therefore of great importance to understand the formation of weld seams inside the welding chamber during extrusion, as affected by extrusion process variables and die design. Previously developed physical simulation methods could not fully reproduce the thermomechanical conditions inside the welding chamber of porthole die. In this research, a novel physical simulation method for the investigation of weld seam formation during extrusion was developed. With a tailor-designed tooling set mounted on a universal testing machine, the effects of temperature, speed, and strain on the weld seam quality of the 6063 alloy were investigated. The strains inside the welding chamber were found to be of paramount importance for the bonding of metal streams, accompanied by microstructural changes, i.e., recovery or recrystallization, depending on the local deformation condition. The method was shown to be able to provide guidelines for the design of porthole dies and choice of extrusion process variables, thereby reducing the scrap rate of aluminum extrusion operation.

  10. Superplasticity and cavitation in an aluminum-magnesium alloy

    NASA Astrophysics Data System (ADS)

    Bae, Donghyun

    2000-10-01

    Fundamental issues related to the forming performance of superplastic metals include the mechanisms of flow and cavitation occurring during the forming process. Cavitation beyond a critical amount is damaging to the mechanical behavior of fabricated parts. Therefore, the role of process parameters which influence cavitation must be precisely documented and understood. In this study, (1) the mechanism of deformation, (2) cavity formation and growth, and (3) the effect of forming parameters on cavitation are systematically investigated in a fine grain Al-4.7%Mg-0.8%Mn-0.4%Cu alloy. The mechanical flow response of the alloy is characterized by a new type of step strain-rate test which preserves the initial microstructure of the alloy. Under isostructural condition, sigmoidal log s vs. log 3˙ relationship is determined and then analyzed by using a grain-mantle based quantitative model1 for superplastic flow. The activation energies in both grain-mantle creep and core creep are analyzed, and the overall controlling mechanism is found to be dislocation glide and climb. Grain-mantle creep rate in the low strain-rate region is found to be enhanced many times due to a high concentration of vacancies near grain boundaries. Cavitation caused by superplastic straining under uniaxial tension is evaluated by the SEM (for < 0.5mum size) and the number and size of cavities are monitored by image analysis through optical microscopy. Growth of pre-existing cavities and nucleation and growth of new cavities at grain boundary particles are monitored with increasing strain. Cavity nucleation and growth occur in two stages: crack-like growth along the particle-matrix interface by a constrained growth process, and beyond complete debonding growth via plastic deformation of the matrix which is modeled here. Stresses and strain-rates near the void are intensified due to the perturbed flow field near the void, and not relaxed during the time frame associated with superplastic deformation

  11. Mechanisms of Corrosion Fatigue in High Strength I/M (Ingot Metallurgy) and P/M (Powder Metallurgy) Aluminum Alloys.

    DTIC Science & Technology

    1983-02-01

    second year effort was devoted to the study of 7075 -T651 (I/Il) alloy, and X7091-T7E69 and X7091-T7E70 (P/M) alloys. The kinetics of fatigue crack...Qualification and Microstructural Characterization 6 3.2 Kinetics of Fatigue Crack Growth 7 3.2.1 7075 -T651 (I/M) Aluminum Alloy 8 3.2.2 X7091-T7E69...and X7091-T7E70 (P/M) Aluminum Alloys 10 3.2.3 Comparison between I/M and P/M Alloys and Discussions 12 3.3 Fractographic Analysis 14 3.3.1 7075 -T651

  12. A Fundamental Study of Laser Beam Welding Aluminum-Lithium Alloy 2195 for Cryogenic Tank Applications

    NASA Technical Reports Server (NTRS)

    Martukanitz, R. P.; Jan. R.

    1996-01-01

    Based on the potential for decreasing costs of joining stiffeners to skin by laser beam welding, a fundamental research program was conducted to address the impediments identified during an initial study involving laser beam welding of aluminum-lithium alloys. Initial objectives of the program were the identification of governing mechanism responsible for process related porosity while establishing a multivariant relationship between process parameters and fusion zone geometry for laser beam welds of alloy 2195. A three-level fractional factorial experiment was conducted to establish quantitative relationships between primary laser beam processing parameters and critical weld attributes. Although process consistency appeared high for welds produced during partial completion of this study, numerous cracks on the top-surface of the welds were discovered during visual inspection and necessitated additional investigations concerning weld cracking. Two experiments were conducted to assess the effect of filler alloy additions on crack sensitivity: the first experiment was used to ascertain the effects of various filler alloys on cracking and the second experiment involved modification to process parameters for increasing filler metal dilution. Results indicated that filler alloys 4047 and 4145 showed promise for eliminating cracking.

  13. 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.

  14. Damage by eutectic particle cracking in aluminum casting alloys A356/357

    NASA Astrophysics Data System (ADS)

    Wang, Q. G.; Caceres, C. H.; Griffiths, J. R.

    2003-12-01

    The strain dependence of particle cracking in aluminum alloys A356/357 in the T6 temper has been studied in a range of microstructures produced by varying solidification rate and Mg content, and by chemical (Sr) modification of the eutectic silicon. The damage accumulates linearly with the applied strain for all microstructures, but the rate depends on the secondary dendrite arm spacing and modification state. Large and elongated eutectic silicon particles in the unmodified alloys and large π-phase (Al9FeMg3Si5) particles in alloy A357 show the greatest tendency to cracking. In alloy A356, cracking of eutectic silicon particles dominates the accumulation of damage while cracking of Fe-rich particles is relatively unimportant. However, in alloy A357, especially with Sr modification, cracking of the large π-phase intermetallics accounts for the majority of damage at low and intermediate strains but becomes comparable with silicon particle cracking at large strains. Fracture occurs when the volume fraction of cracked particles (eutectic silicon and Fe-rich intermetallics combined) approximates 45 pct of the total particle volume fraction or when the number fraction of cracked particles is about 20 pct. The results are discussed in terms of Weibull statistics and existing models for dispersion hardening.

  15. 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.

  16. Effects of temperature and blank holding force on biaxial forming behavior of aluminum sheet alloys

    NASA Astrophysics Data System (ADS)

    Li, Daoming; Ghosh, Amit K.

    2004-06-01

    Biaxial forming behavior is investigated for three aluminum sheet alloys (Al 5182 containing 1% Mn (5182+Mn), Al 5754, and 6111-T4) using a heated die and punch in the warm forming temperature range of 200-350 °C. It is found that, while all three alloys exhibit significant improvement in their formability compared with that at room temperature, the non-heat-treatable alloys 5182 + Mn and 5754 give higher part depths than that of heat-treatable 6111-T4. The formability generally increases with decreasing BHP (BHP), but increasing the forming temperature and/or BHP minimizes the wrinkling tendency and improves the forming performance. The stretchability of the sheet alloys increase with increasing temperature and increasing BHP. For the alloys and forming conditions involved in the current study, the formability, measured in terms of part depth, comes mainly from the drawing of metal into the die cavity, although stretching effects do influence the overall forming behavior. The optimum formability is achieved by setting the die temperature 50 °C higher than the punch temperature to enhance the drawing component. Setting the die temperature higher than the punch temperature also improves the strain distribution in a part in such a manner that postpones necking and fracture by altering the location of greatest thinning.

  17. Stress corrosion cracking of superplastically formed 7475 aluminum alloy

    SciTech Connect

    Tsai, T.C.; Chang, J.C.; Chuang, T.H.

    1997-10-01

    The effects of biaxial superplastic deformation and postforming heat treatment upon the stress corrosion cracking (SCC) of a fine-grained 7475Al alloy plate have been investigated. For all postforming tempered conditions, increasing the extent of superplastic deformation, which created more cavitations, would decrease the mechanical properties, the SCC resistance, and the corrosion resistance. The influence of cavitation on the decay of elongation of the superplastically formed workpieces is larger than that on the decay of its strength. Post-forming tempered by retrogression and reaging (RRA) treatment could effectively improve the SCC resistance of workpieces in postforming T6 temper while not sacrificing the strength. However, the benefit of improving the SCC resistance by means of the postforming RRA temper was decreased with increasing the extent of superplastic deformation, because the SCC susceptibility increased as the extent of superplastic deformation increased for each postforming tempered condition. The cavitation led to more anodic corrosion potential and pitting potential and to an increase in both corrosion current density and passive current density, which would increase the SCC susceptibility.

  18. Atmospheric stress corrosion cracking of a superplastic 7475 aluminum alloy

    SciTech Connect

    Tsai, T.C.; Chuang, T.H.

    1996-09-01

    The influence of different heat treatments upon the atmospheric stress corrosion cracking (SCC) of fine-grained 7475 Al-alloy plates has been investigated. The small size of the matrix precipitates and grain-boundary precipitates (GBPs) was found to be the main cause of atmospheric SCC susceptibility. Increasing the size of the matrix precipitates and GBPs by increasing the degree of aging could improve the atmospheric SCC resistance. The size of the matrix precipitates was the major factor affecting the atmospheric SCC resistance when GBPs were larger than a critical size that could nucleate hydrogen bubbles. However, if the size of the GBPs was smaller than this critical size, the improvement of atmospheric SCC resistance due to grain refinement, resulting from a more homogeneous slip mode, could not be obtained because hydrogen embrittlement became serious. By measuring the electrical conductivity, the influence of matrix precipitates, but not that of GBPs, on SCC susceptibility could be obtained. Retrogression and reaging (RRA) treatment could effectively improve the atmospheric SCC resistance of T6 temper because RRA temper could produce larger sizes of both the matrix precipitates and GBPs than could T6 tempered condition.

  19. 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.

  20. Effect of temper on seawater corrosion of an aluminum-silicon carbide composite alloy

    SciTech Connect

    Ahmad, Z.; Abdul Aleem, B.J.

    1996-11-01

    The corrosion behavior of annealed (O), as-fabricated (F), and naturally age-hardened (T4) aluminum alloy Al 6013 with 20 vol% silicon carbide in particulate form was investigated in 3.5 wt% sodium chloride and in Arabian Gulf water. Of the three tempers, T4 showed the lowest corrosion rate (0.04 mpy and 2.61 mpy) in deaerated and aerated NaCl, respectively. The corrosion rate in seawater was slightly higher. Predominant forms of corrosion were pitting and intergranular corrosion. Formation of corrosion chimneys was observed. X-ray diffraction Fourier transform infrared spectroscopy and energy dispersive spectroscopy showed intermetallic formation and the presence of a gelatinous film of aluminum hydroxide of bayrite type. The higher corrosion resistance of the T4 temper resulted from finer and more homogeneously distributed precipitates compared to tempers F and O. In view of the alloy`s good corrosion resistance and outstanding ultimate tensile strength, yield strength and specific modulus, it can be considered a strong competitor to Al 2024, Al 2014, and Al 6061, which are used mainly for structural applications.