Corrosion Behavior of Aluminum Alloys in Acidic Media

NASA Astrophysics Data System (ADS)

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

2007-05-01

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

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.

Reaction rates and prediction of thermal instability during aluminum alloy 6061 dissolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

McFarlane, J.; DePaoli, D. W.; Mattus, C. H.

Here, chemical kinetics of dissolution of aluminum alloy 6061 was investigated for the processing of Pu-238 for deep space missions. The rate of dissolution was measured by the heat release and appeared to be controlled by the rate of release of Al(OH) 4 – from the metal surface. Rates of reaction were measured from 273 to 365 K, giving an activation energy of 72 ± 13 kJ•(mol Al) –1 and a pre-exponential factor of 5 ± 3 × 10 9 dm 3mol –1min –1. Minor alloying elements did not appear to affect the reaction kinetics. The average heat of dissolutionmore » was –360 ± 70 kJ•(mol NaAlO 2) –1. When extrapolated to an infinitely dilute solution of aluminum, kJ•(mol NaAlO 2) –1.« less

Reaction rates and prediction of thermal instability during aluminum alloy 6061 dissolution

DOE PAGES

McFarlane, J.; DePaoli, D. W.; Mattus, C. H.

2017-11-10

Here, chemical kinetics of dissolution of aluminum alloy 6061 was investigated for the processing of Pu-238 for deep space missions. The rate of dissolution was measured by the heat release and appeared to be controlled by the rate of release of Al(OH) 4 – from the metal surface. Rates of reaction were measured from 273 to 365 K, giving an activation energy of 72 ± 13 kJ•(mol Al) –1 and a pre-exponential factor of 5 ± 3 × 10 9 dm 3mol –1min –1. Minor alloying elements did not appear to affect the reaction kinetics. The average heat of dissolutionmore » was –360 ± 70 kJ•(mol NaAlO 2) –1. When extrapolated to an infinitely dilute solution of aluminum, kJ•(mol NaAlO 2) –1.« less

Influence of SMAT Parameters on Microstructural and Mechanical Properties of Al-Mg-Si Alloy AA 6061

NASA Astrophysics Data System (ADS)

Anand Kumar, S.; Satish Kumar, P.; Ganesh Sundara Raman, S.; Sankara Narayanan, T. S. N.

2017-04-01

In the present work, the influence of surface mechanical attrition treatment (SMAT) parameters on the microstructural and mechanical properties of an aluminum-magnesium-silicon alloy AA 6061 was studied using design of experiment technique. Balls of three different diameters were used, and SMAT was done for three different durations. The microstructural features of the surface layer fabricated by SMAT were characterized by cross-sectional scanning electron microscopic observations, x-ray diffraction technique and transmission electron microscopy. The microindentation hardness, nanoindentation hardness and surface roughness were determined. Due to SMAT, nanocrystallites formed on the surface and near-surface regions, and hardness and surface roughness increased. The ball diameter was the most influencing SMAT parameter compared to the treatment duration. However, interaction between ball diameter and treatment duration could not be ignored. Regression equations were developed relating the process parameters to the surface properties. The ball diameter and treatment duration could thus be properly selected as per the required values of roughness and/or the hardness.

[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.

Joining sheet aluminum AA6061-T4 to cast magnesium AM60B by vaporizing foil actuator welding: Input energy, interface, and strength

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Bert; Vivek, Anupam; Daehn, Glenn S.

Dissimilar joining of sheet aluminum AA6061-T4 to cast magnesium AM60B was achieved by vaporizing foil actuator welding (VFAW). Three input energy levels were used (6, 8, and 10 kJ), and as a trend, higher input energies resulted in progressively higher flyer velocities, more pronounced interfacial wavy features, larger weld zones, higher peel strengths, and higher peel energies. In all cases, weld cross section revealed a soundly bonded interface characterized by well-developed wavy features and lack of voids and continuous layers of intermetallic compounds (IMCs). At 10 kJ input energy, flyer speed of 820 m/s, peel strength of 22.4 N/mm, andmore » peel energy of 5.2 J were obtained. In lap-shear, failure occurred in AA6061- T4 flyer at 97% of the base material’s peak tensile load. Peel samples failed along the weld interface, and the AM60B-side of the fracture surface showed thin, evenly-spaced lines of Al residuals which had been torn out of the base AA6061-T4 in a ductile fashion and transferred over to the AM60B side, indicating very strong AA6061-T4/AM60B bond in these areas. Furthermore, this work demonstrates VFAW’s capability in joining dissimilar lightweight metals such as Al/Mg, which is expected to be a great enabler in the ongoing push for vehicle weight reduction.« less

Joining sheet aluminum AA6061-T4 to cast magnesium AM60B by vaporizing foil actuator welding: Input energy, interface, and strength

DOE PAGES

Liu, Bert; Vivek, Anupam; Daehn, Glenn S.

2017-09-19

Dissimilar joining of sheet aluminum AA6061-T4 to cast magnesium AM60B was achieved by vaporizing foil actuator welding (VFAW). Three input energy levels were used (6, 8, and 10 kJ), and as a trend, higher input energies resulted in progressively higher flyer velocities, more pronounced interfacial wavy features, larger weld zones, higher peel strengths, and higher peel energies. In all cases, weld cross section revealed a soundly bonded interface characterized by well-developed wavy features and lack of voids and continuous layers of intermetallic compounds (IMCs). At 10 kJ input energy, flyer speed of 820 m/s, peel strength of 22.4 N/mm, andmore » peel energy of 5.2 J were obtained. In lap-shear, failure occurred in AA6061- T4 flyer at 97% of the base material’s peak tensile load. Peel samples failed along the weld interface, and the AM60B-side of the fracture surface showed thin, evenly-spaced lines of Al residuals which had been torn out of the base AA6061-T4 in a ductile fashion and transferred over to the AM60B side, indicating very strong AA6061-T4/AM60B bond in these areas. Furthermore, this work demonstrates VFAW’s capability in joining dissimilar lightweight metals such as Al/Mg, which is expected to be a great enabler in the ongoing push for vehicle weight reduction.« less

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

NASA Technical Reports Server (NTRS)

Reynolds, A. P.

1992-01-01

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

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.

Dynamic Response and Microstructure Evolution of AA2219-T4 and AA2219-T6 Aluminum Alloys

NASA Astrophysics Data System (ADS)

Olasumboye, A.; Owolabi, G.; Odeshi, A.; Zeytinci, A.; Yilmaz, N.

2018-02-01

In this study, the dynamic deformation behavior of AA2219 aluminum alloy was investigated in two different temper conditions: T4 and T6, with a view to determining the effect of heat treatment on the microstructure and flow behavior of the material under high strain rates. Split Hopkinson pressure bar experiment was used in determining the dynamic response of the alloy while a digital image correlation system was employed in visualizing and tracking the surface deformation of the specimens. Optical microscopy and scanning electron microscopy were used to assess the microstructure of the material after following standard metallographic specimen preparation techniques. The results obtained showed heterogeneous deformation of the alloy in the two temper conditions. It was observed that the dynamic mechanical behavior of each sample preparation was dependent on its strength properties due to aging type, which in turn controls the metamorphosis of the strengthening precipitates and the initial microstructure. At the maximum strain rate of 3500 s-1, transformed bands leading to crack nucleation was observed in the AA2219-T4 aluminum alloy while AA2219-T6 had fractured at the same strain rate. The modes of crack formation and growth in the two alloys were found to be similar: nucleation, growth and coalescence of voids. However, shear band bifurcation phenomenon was observed only in the AA2219-T6 alloy.

Dynamic Response and Microstructure Evolution of AA2219-T4 and AA2219-T6 Aluminum Alloys

NASA Astrophysics Data System (ADS)

Olasumboye, A.; Owolabi, G.; Odeshi, A.; Zeytinci, A.; Yilmaz, N.

2018-06-01

In this study, the dynamic deformation behavior of AA2219 aluminum alloy was investigated in two different temper conditions: T4 and T6, with a view to determining the effect of heat treatment on the microstructure and flow behavior of the material under high strain rates. Split Hopkinson pressure bar experiment was used in determining the dynamic response of the alloy while a digital image correlation system was employed in visualizing and tracking the surface deformation of the specimens. Optical microscopy and scanning electron microscopy were used to assess the microstructure of the material after following standard metallographic specimen preparation techniques. The results obtained showed heterogeneous deformation of the alloy in the two temper conditions. It was observed that the dynamic mechanical behavior of each sample preparation was dependent on its strength properties due to aging type, which in turn controls the metamorphosis of the strengthening precipitates and the initial microstructure. At the maximum strain rate of 3500 s-1, transformed bands leading to crack nucleation was observed in the AA2219-T4 aluminum alloy while AA2219-T6 had fractured at the same strain rate. The modes of crack formation and growth in the two alloys were found to be similar: nucleation, growth and coalescence of voids. However, shear band bifurcation phenomenon was observed only in the AA2219-T6 alloy.

An electron back-scattered diffraction study on the microstructure evolution of severely deformed aluminum AI6061 alloy

NASA Astrophysics Data System (ADS)

Vaseghi, M.; Karimi Taheri, A.; Kim, H. S.

2014-08-01

In this paper dynamic strain ageing behavior in an Al-Mg-Si alloy related to equal channel angular pressing (ECAP) was investigated. In order to examine the combined plastic deformation and ageing effects on microstructure evolutions and strengthening characteristics, the Al6061 alloy were subjected to phi=90° ECAP die for up to 4 passes via route Bc at high temperatures. For investigating the effects of ageing temperature and strain rate in ECAP, Vickers hardness tests were performed. The combination of the ECAP process with dynamic ageing at higher temperatures resulted in a significant increase in hardness. The microstructural evolution of the samples was studied using electron back-scattering diffraction (EBSD). The grains of Al6061 aluminum alloy were refined significantly at 100 and 150 °C with greater pass numbers and the distributions of grain size tended to be more uniform with pass number increasing. Frequency of sub-boundaries and low angle grain boundaries (LAGBs) increased at initial stage of deformation, and sub-boundaries and LAGBs evolved into highangle grain boundaries (HAGBs) with further deformation, which resulted in the high frequency of HAGBs in the alloy after ECAP 4 passes.

Analysis of the flow property of aluminum alloy AA6016 based on the fracture morphology using the hydroforming technology

NASA Astrophysics Data System (ADS)

Lang, Lihui; Zhang, Quanda; Sun, Zhiying; Wang, Yao

2017-09-01

In this paper, the hydraulic bulging experiments were respectively carried out using AA6016-T4 aluminum alloy and AA6016-O aluminum alloy, and the deformation properties and fracture mechanism of aluminum alloy under the conditions of thermal and hydraulic were analyzed. Firstly, the aluminum alloy AA6016 was dealt with two kinds of heat treatment systems such as solid solution heat treatment adding natural ageing and full annealing, then the aluminum alloy such as AA6016-T4 and AA6016-O were obtained. In the same working environment, the two kinds of materials were used in the process of hydraulic bulging experiments, according to the observation and measurement of the deformation sizes of grid circles and material thicknesses near the fracture region, the flow properties and development trend of fracture defect of the materials were analyzed comprehensively from the perspective of qualitative analysis and quantitative analysis; Secondly, the two kinds of materials were sampled in different regions of the fracture area and the microstructure morphology of the fracture was observed by the scanning electron microscope (SEM). The influence laws of the heat treatment systems on the fracture defect of the aluminum alloy under the condition of the liquid pressure were studied preliminarily by observing the distribution characteristics of the fracture microstructure morphology of dimple. At the same time, the experimental research on the ordinary stamping forming process of AA6016-O was carried out and the influence law of different forming process on the fracture defect of the aluminum alloy material was studied by observing the distribution of the fracture microstructure morphology; Finally, the development process of the fracture defect of aluminum alloy sheet was described theoretically from the view of the stress state.

Dry Sliding Tribological Studies of AA6061-B4C-Gr Hybrid Composites

NASA Astrophysics Data System (ADS)

Monikandan, V. V.; Joseph, M. A.; Rajendrakumar, P. K.

2016-10-01

The dry sliding behavior of stir-cast AA6061-10 wt.% B4C composites containing 2.5, 5 and 7.5 wt.% graphite particles was studied as a function of applied load, sliding speed and sliding distance on a pin-on-disk tribotester. The wear rate and friction coefficient increased with increase in applied load and sliding distance. The increase in graphite addition reduced the increase in wear rate and friction coefficient in the sliding speed range 2-2.5 m/s. Scanning electron microscopy of the worn pin revealed a graphite tribolayer, and transmission electron microscopy revealed overlapping deformation bands under 30 N applied load. Upon increasing the applied load to 40 N, welded region with fine crystalline structure was formed due to dynamic recrystallization of AA6061 alloy matrix.

Gas tungsten arc welding of aluminum alloys 6XXX. Welding procedure specification. Supplement 1. Records of procedure qualification tests. [6061 and 6063

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wodtke, C.H.; Frizzell, D.R.; Plunkett, W.A.

1986-06-01

Procedure WPS-1003 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for gas tungsten arc welding of aluminum alloys 6061 and 6063 (P-23), in thickness range 0.035 to 0.516 inch; filler metal is ER4043 (F-23) or ER5356 (F-22); shielding gas is argon.

Fractal nature of aluminum alloys substructures under creep and its implications

NASA Astrophysics Data System (ADS)

Fernández, R.; Bruno, G.; González-Doncel, G.

2018-04-01

The present work offers an explanation for the variation of the power-law stress exponent, n, with the stress σ normalized to the shear modulus G in aluminum alloys. The approach is based on the assumption that the dislocation structure generated with deformation has a fractal nature. It fully explains the evolution of n with σ/G even beyond the so-called power law breakdown region. Creep data from commercially pure Al99.8%, Al-3.85%Mg, and ingot AA6061 alloy tested at different temperatures and stresses are used to validate the proposed ideas. Finally, it is also shown that the fractal description of the dislocation structure agrees well with current knowledge.

Effect of KOH to Na2SiO3 Ratio on Microstructure and Hardness of Plasma Electrolytic Oxidation Coatings on AA 6061 Alloy

NASA Astrophysics Data System (ADS)

Sharma, Ashutosh; Jang, Yong-Joo; Jung, Jae Pil

2017-10-01

In this study, plasma electrolytic oxidation (PEO) process has been employed to fabricate alumina coatings on AA 6061 aluminum alloy from an electrolyte containing water glass (Na2SiO3) and alkali (KOH). The effect of deposition time and the alkali to water glass (KOH: Na2SiO3) composition ratio on the coating morphology and properties are studied. The different phases of the oxide layer and microstructure are investigated by x-ray diffraction, scanning electron microscopy, and atomic force microscopy. The results indicate that initially γ-Al2O3 forms in the coating, and as the processing time is increased from 5 to 60 minutes, α-Al2O3 phase becomes prominent. Further, higher the content of Na2SiO3, higher is the hardness and coating growth rate due to the formation of stable α-Al2O3 and Al-Si-O phase. It has been reported that the optimum properties of the PEO coatings can be obtained at a ratio of KOH: Na2SiO3 ≈ 15:10 followed by 10:10.

Multi-Objective Optimization of Friction Stir Welding Process Parameters of AA6061-T6 and AA7075-T6 Using a Biogeography Based Optimization Algorithm

PubMed Central

Tamjidy, Mehran; Baharudin, B. T. Hang Tuah; Paslar, Shahla; Matori, Khamirul Amin; Sulaiman, Shamsuddin; Fadaeifard, Firouz

2017-01-01

The development of Friction Stir Welding (FSW) has provided an alternative approach for producing high-quality welds, in a fast and reliable manner. This study focuses on the mechanical properties of the dissimilar friction stir welding of AA6061-T6 and AA7075-T6 aluminum alloys. The FSW process parameters such as tool rotational speed, tool traverse speed, tilt angle, and tool offset influence the mechanical properties of the friction stir welded joints significantly. A mathematical regression model is developed to determine the empirical relationship between the FSW process parameters and mechanical properties, and the results are validated. In order to obtain the optimal values of process parameters that simultaneously optimize the ultimate tensile strength, elongation, and minimum hardness in the heat affected zone (HAZ), a metaheuristic, multi objective algorithm based on biogeography based optimization is proposed. The Pareto optimal frontiers for triple and dual objective functions are obtained and the best optimal solution is selected through using two different decision making techniques, technique for order of preference by similarity to ideal solution (TOPSIS) and Shannon’s entropy. PMID:28772893

Multi-Objective Optimization of Friction Stir Welding Process Parameters of AA6061-T6 and AA7075-T6 Using a Biogeography Based Optimization Algorithm.

PubMed

Tamjidy, Mehran; Baharudin, B T Hang Tuah; Paslar, Shahla; Matori, Khamirul Amin; Sulaiman, Shamsuddin; Fadaeifard, Firouz

2017-05-15

The development of Friction Stir Welding (FSW) has provided an alternative approach for producing high-quality welds, in a fast and reliable manner. This study focuses on the mechanical properties of the dissimilar friction stir welding of AA6061-T6 and AA7075-T6 aluminum alloys. The FSW process parameters such as tool rotational speed, tool traverse speed, tilt angle, and tool offset influence the mechanical properties of the friction stir welded joints significantly. A mathematical regression model is developed to determine the empirical relationship between the FSW process parameters and mechanical properties, and the results are validated. In order to obtain the optimal values of process parameters that simultaneously optimize the ultimate tensile strength, elongation, and minimum hardness in the heat affected zone (HAZ), a metaheuristic, multi objective algorithm based on biogeography based optimization is proposed. The Pareto optimal frontiers for triple and dual objective functions are obtained and the best optimal solution is selected through using two different decision making techniques, technique for order of preference by similarity to ideal solution (TOPSIS) and Shannon's entropy.

Microstructure and Mechanical Properties of Friction Stir Welded Aluminum Alloy/Stainless Steel Lap Joints

NASA Astrophysics Data System (ADS)

Ogura, Tomo; Nishida, Taichi; Nishida, Hidehito; Yoshikawa, Syuhei; Yoshida, Takumi; Omichi, Noriko; Fujimoto, Mitsuo; Hirose, Akio

The mechanical properties and interfacial microstructure of an aluminum alloy/stainless steel dissimilar lap joint using friction stir welding (FSW) were characterized. In an FSWed A3003 aluminum alloy-SUS304 steel lap joint, the strength on the advancing side was larger than that at the retreating side. TEM observation indicated that a sound joint can be obtained from the stage of the formation of the amorphous layer owing to the mechanical alloying effects before the formation of intermetallic compounds. This lap joining technique was also successfully applied to A6061-T6 aluminum alloy-grooved SUS304 plates. The maximum tensile strength of the lap joint was approximately the same as that of the base alloy, however, the proof stress of the joint decreased with the dissolution of the β″ phase in the A6061 aluminium alloy, which is caused by the generation of heat during friction stir welding.

X-ray peak broadening analysis of AA 6061{sub 100-x} - x wt.% Al{sub 2}O{sub 3} nanocomposite prepared by mechanical alloying

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sivasankaran, S., E-mail: sivasankarangs1979@gmail.com; Sivaprasad, K., E-mail: ksp@nitt.edu; Narayanasamy, R., E-mail: narayan@nitt.edu

2011-07-15

Nanocrystalline AA 6061 alloy reinforced with alumina (0, 4, 8, and 12 wt.%) in amorphized state composite powder was synthesized by mechanical alloying and consolidated by conventional powder metallurgy route. The as-milled and as-sintered (573 K and 673 K) nanocomposites were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The peaks corresponding to fine alumina was not observed by XRD patterns due to amorphization. Using high-resolution transmission electron microscope, it is confirmed that the presence of amorphized alumina observed in Al lattice fringes. The crystallite size, lattice strain, deformation stress, and strain energy density of AA 6061 matrixmore » were determined precisely from the first five most intensive reflection of XRD using simple Williamson-Hall models; uniform deformation model, uniform stress deformation model, and uniform energy density deformation model. Among the developed models, uniform energy density deformation model was observed to be the best fit and realistic model for mechanically alloyed powders. This model evidenced the more anisotropic nature of the ball milled powders. The XRD peaks of as-milled powder samples demonstrated a considerable broadening with percentage of reinforcement due to grain refinement and lattice distortions during same milling time (40 h). The as-sintered (673 K) unreinforced AA 6061 matrix crystallite size from well fitted uniform energy density deformation model was 98 nm. The as-milled and as-sintered (673 K) nanocrystallite matrix sizes for 12 wt.% Al{sub 2}O{sub 3} well fitted by uniform energy density deformation model were 38 nm and 77 nm respectively, which indicate that the fine Al{sub 2}O{sub 3} pinned the matrix grain boundary and prevented the grain growth during sintering. Finally, the lattice parameter of Al matrix in as-milled and as-sintered conditions was also investigated in this paper. Research highlights: {yields} Integral breadth methods using

Experiments and simulation for 6061-T6 aluminum alloy resistance spot welded lap joints

NASA Astrophysics Data System (ADS)

Florea, Radu Stefanel

This comprehensive study is the first to quantify the fatigue performance, failure loads, and microstructure of resistance spot welding (RSW) in 6061-T6 aluminum (Al) alloy according to welding parameters and process sensitivity. The extensive experimental, theoretical and simulated analyses will provide a framework to optimize the welding of lightweight structures for more fuel-efficient automotive and military applications. The research was executed in four primary components. The first section involved using electron back scatter diffraction (EBSD) scanning, tensile testing, laser beam profilometry (LBP) measurements, and optical microscopy(OM) images to experimentally investigate failure loads and deformation of the Al-alloy resistance spot welded joints. Three welding conditions, as well as nugget and microstructure characteristics, were quantified according to predefined process parameters. Quasi-static tensile tests were used to characterize the failure loads in specimens based upon these same process parameters. Profilometer results showed that increasing the applied welding current deepened the weld imprints. The EBSD scans revealed the strong dependency between the grain sizes and orientation function on the process parameters. For the second section, the fatigue behavior of the RSW'ed joints was experimentally investigated. The process optimization included consideration of the forces, currents, and times for both the main weld and post-heating. Load control cyclic tests were conducted on single weld lap-shear joint coupons to characterize the fatigue behavior in spot welded specimens. Results demonstrate that welding parameters do indeed significantly affect the microstructure and fatigue performance for these welds. The third section comprised residual strains of resistance spot welded joints measured in three different directions, denoted as in-plane longitudinal, in-plane transversal, and normal, and captured on the fusion zone, heat affected zone

Wear behaviors of pure aluminum and extruded aluminum alloy (AA2024-T4) under variable vertical loads and linear speeds

NASA Astrophysics Data System (ADS)

Jung, Jeki; Oak, Jeong-Jung; Kim, Yong-Hwan; Cho, Yi Je; Park, Yong Ho

2017-11-01

The aim of this study was to investigate the transition of wear behavior for pure aluminum and extruded aluminum alloy 2024-T4 (AA2024-T4). The wear test was carried using a ball-on-disc wear testing machine at various vertical loads and linear speeds. The transition of wear behaviors was analyzed based on the microstructure, wear tracks, wear cross-section, and wear debris. The critical wear rates for each material are occurred at lower linear speed for each vertical load. The transition of wear behavior was observed in which abrasion wears with the generation of an oxide layer, fracture of oxide layer, adhesion wear, severe adhesion wear, and the generation of seizure occurred in sequence. In case of the pure aluminum, the change of wear debris occurred in the order of blocky, flake, and needle-like debris. Cutting chip, flake-like, and coarse flake-like debris was occurred in sequence for the extruded AA2024-T4. The transition in the wear behavior of extruded AA2024-T4 occurred slower than in pure aluminum.

Dynamic Response of AA2519 Aluminum Alloy under High Strain Rates

NASA Astrophysics Data System (ADS)

Olasumboye, Adewale Taiwo

Like others in the AA2000 series, AA2519 is a heat-treatable Al-Cu alloy. Its excellent ballistic properties and stress corrosion cracking resistance, combined with other properties, qualify it as a prime candidate for armored vehicle and aircraft applications. However, available data on its high strain-rate response remains limited. In this study, AA2519 aluminum alloy was investigated in three different temper conditions: T4, T6, and T8, to determine the effects of heat treatment on the microstructure and dynamic deformation behavior of the material at high strain rates ranging within 1000 ≤ epsilon ≤ 4000 s-1. Split Hopkinson pressure bar integrated with digital image correlation system was used for mechanical response characterization. Optical microscopy and scanning electron microscopy were used to assess the microstructure of the material after following standard metallographic specimen preparation techniques. Results showed heterogeneous deformation in the three temper conditions. It was observed that dynamic behavior in each condition was dependent on strength properties due to the aging type controlling the strengthening precipitates produced and initial microstructure. At 1500 s -1, AA2519-T6 exhibited peak dynamic yield strength and flow stress of 509 and 667 MPa respectively, which are comparable with what were observed in T8 condition at higher rate of 3500 s-1 but AA2519-T4 showed the least strength and flow stress properties. Early stress collapse, dynamic strain aging, and higher susceptibility to shear band formation and fracture were observed in the T6 condition within the selected range of high strain rates. The alloy's general mode of damage evolution was by dispersoid particle nucleation, shearing and cracking.

Intergranular corrosion in AA5XXX aluminum alloys with discontinuous precipitation at the grain boundaries

NASA Astrophysics Data System (ADS)

Bumiller, Elissa

The US Navy currently uses AA5xxx aluminum alloys for structures exposed to a marine environment. These alloys demonstrate excellent corrosion resistance over other aluminum alloys (e.g., AA2xxx or AA7xxx) in this environment, filling a niche in the marine structures market when requiring a light-weight alternative to steel. However, these alloys are susceptible to localized corrosion; more specifically, intergranular corrosion (IGC) is of concern. IGC of AA5xxx alloys due to the precipitation of beta phase on the grain boundaries is a well-established phenomenon referred to as sensitization. At high degrees of sensitization, the IGC path is a continuous anodic path of beta phase particles. At lower degrees of sensitization, the beta phase coverage at the grain boundaries is not continuous. The traditional ranges of susceptibility to IGC as defined by ASTM B928 are in question due to recent studies. These studies showed that even at mid range degrees of sensitization where the beta phase is no longer continuous, IGC may still occur. Previous thoughts on IGC of these alloy systems were founded on the idea that once the grain boundary precipitate became discontinuous the susceptibility to IGC was greatly reduced. Additionally, IGC susceptibility has been defined metallurgically by compositional gradients at the grain boundaries. However, AA5xxx alloys show no compositional gradients at the grain boundaries, yet are still susceptible to IGC. The goal of this work is to establish criteria necessary for IGC to occur given no continuous beta phase path and no compositional gradient at the grain boundaries. IGC performance of the bulk alloy system AA5083 has been studied along with the primary phases present in the IGC system: alpha and beta phases using electrochemistry and modeling as the primary tools. Numerical modeling supports that at steady-state the fissure tip is likely saturated with Mg in excess of the 4% dissolved in the matrix. By combining these results

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

DOE PAGES

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

2015-05-13

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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

Microstructural variation through weld thickness and mechanical properties of peened friction stir welded 6061 aluminum alloy joints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdulstaar, Mustafa A., E-mail: mustafa.abdulstaar

The current study examined the effect of microstructure variation on the development of mechanical properties in friction stir welded joints of 6061-T6 aluminum alloy, which were subsequently processed by shot peening (SP). Following to FSW, fatigue specimens were extracted perpendicularly to the welding direction. Surface Skimming to 0.5 mm from crown and root sides of the joint was made and SP was later applied on the two sides using ceramic shots of two different Almen intensities of 0.18 mmA and 0.24 mmA. Microstructural examination by electron back scattered diffraction (EBSD) indicated variation in the grain refinement of the weld zone,more » with coarsest grains (5 μm) at the crown side and finest grains (2 μm) at the root side. Reduction of microhardness to 60 HV occurred in the weld zone for samples in FSW condition. Application of SP promoted significant strain hardening at the crown side, with Almen intensities of 0.24 mmA providing maximum increase in microhardness to 120 HV. On the contrary, only a maximum microhardness of 75 HV was obtained at the root side. The difference in strain hardening capability at the two sides was strongly dependent on grain size. The two Almen intensities produced similar distribution of compressive residual stresses in the subsurface regions that led to enhance the fatigue strength to the level of base metal for N ≥ 10{sup 5} cycles. Yet, the increase in fatigue strength was more pronounced with increasing Almen intensity to 0.24 mmA, demonstrating further enhancement by strain hardening. - Highlights: • Grain refinement was observed after friction stir welding of AA 6061-T6. • Reduction in microhardness and fatigue strength were obtained after welding. • Variation in grain refinement led to different hardening behavior after peening. • Shot peening induced beneficial compressive residual stresses. • Shot peening and surface skimming markedly improved the fatigue performance.« less

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%.

Aluminum-lithium alloys in helicopters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, A.F.

1997-10-01

Aluminium-lithium alloys are widely applied on the EH101 helicopter, designed and built jointly by GKN Westland Helicopters of England and Agusta S.p.A. of Italy. With the exception of the powder metallurgy alloy AA 5091, all the current commercially available aluminum-lithium alloys are produced by direct-chill casting, and require a precipitation-aging heat treatment to achieve the required properties. In aluminum-lithium alloys containing greater than 1.3% (by weight) of lithium, the intermetallic phase {delta}{prime}-Al{sub 3}Li precipitates upon natural or artificial aging, but the associated strengthening effect is insufficient to meet the medium or high strength levels usually required (the damage tolerant tempermore » in AA 8090 is an exception).« less

Change of Hot Cracking Susceptibility in Welding of High Strength Aluminum Alloy AA 7075

NASA Astrophysics Data System (ADS)

Holzer, M.; Hofmann, K.; Mann, V.; Hugger, F.; Roth, S.; Schmidt, M.

High strength aluminum alloys are known as hard to weld alloys due to their high hot crack susceptibility. However, they have high potential for applications in light weight constructions of automotive industry and therefore it is needed to increase weldability. One major issue is the high hot cracking susceptibility. Vaporization during laser beam welding leads to a change of concentration of the volatile elements magnesium and zinc. Hence, solidification range of the weld and therefore hot cracking susceptibility changes. Additionally, different welding velocities lead to changed solidification conditions with certain influence on hot cracking. This paper discusses the influence of energy per unit length during laser beam welding of AA 7075 on the change of element concentration in the weld seam and the resulting influence on hot cracking susceptibility. Therefore EDS-measurements of weld seams generated with different velocities are performed to determine the change of element concentration. These quantitative data is used to numerically calculate the solidification range in order to evaluate its influence on the hot cracking susceptibility. Besides that, relative hot crack length and mechanical properties are measured. The results increase knowledge about welding of high strength aluminum alloy AA 7075 and hence support further developing of the welding process.

A Comparative Study on Permanent Mold Cast and Powder Thixoforming 6061 Aluminum Alloy and Sicp/6061Al Composite: Microstructures and Mechanical Properties.

PubMed

Zhang, Xuezheng; Chen, Tijun; Qin, He; Wang, Chong

2016-05-24

Microstructural and mechanical characterization of 10 vol% SiC particles (SiC p ) reinforced 6061 Al-based composite fabricated by powder thixoforming (PTF) was investigated in comparison with the PTF and permanent mold cast (PMC) 6061 monolithic alloys. The results reveal that the microstructure of the PMC alloy consists of coarse and equiaxed α dendrites and interdendritic net-like eutectic phases. However, the microstructure of the PTF composite, similar to that of the PTF alloy, consists of near-spheroidal primary particles and intergranular secondarily solidified structures except SiC p , which are distributed in the secondarily solidified structures. The eutectics amount in the PTF materials is distinctly lower than that in the PMC alloy, and the microstructures of the former materials are quite compact while that of the latter alloy is porous. Therefore, the PTF alloy shows better tensile properties than the PMC alloy. Owing to the existence of the SiC reinforcing particles, the PTF composite attains an ultimate tensile strength and yield strength of 230 MPa and 128 MPa, representing an enhancement of 27.8% and 29.3% than those (180 MPa and 99 MPa) of the PTF alloy. A modified model based on three strengthening mechanisms was proposed to calculate the yield strength of the PTF composite. The obtained theoretical results were quite consistent with the experimental data.

Enhancing Corrosion and Wear Resistance of AA6061 by Friction Stir Processing with Fe78Si9B13 Glass Particles

PubMed Central

Guo, Lingyu; Liu, Yan; Shen, Kechang; Song, Chaoqun; Yang, Min; Kim, Kibuem; Wang, Weimin

2015-01-01

The AA6061-T6 aluminum alloy samples including annealed Fe78Si9B13 particles were prepared by friction stir processing (FSP) and investigated by various techniques. The Fe78Si9B13-reinforced particles are uniformly dispersed in the aluminum alloy matrix. The XRD results indicated that the lattice parameter of α-Al increases and the preferred orientation factors F of (200) plane of α-Al reduces after friction stir processing. The coefficient of thermal expansion (CTE) for FSP samples increases at first with the temperature but then decreases as the temperature further increased, which can be explained by the dissolving of Mg and Si from β phase and Fe78Si9B13 particles. The corrosion and wear resistance of FSP samples have been improved compared with that of base metal, which can be attributed to the reduction of grain size and the CTE mismatch between the base metal and reinforced particles by FSP, and the lubrication effect of Fe78Si9B13 particles also plays a role in improving wear resistance. In particular, the FSP sample with reinforced particles in amorphous state exhibited superior corrosion and wear resistance due to the unique metastable structure. PMID:28793492

Synthesis and wear behavior of aluminum 6061 alloy reinforced with carbon nanotubes

NASA Astrophysics Data System (ADS)

Khalil, Abdullah

In the present work, Al6061 alloy was uniformly reinforced with 0.5, 0.75, 1 and 2 wt. % Carbon Nanotubes (CNTs) using two way dispersion method. For consolidation, Spark Plasma Sintering (SPS) was used which resulted in very high densification for the matrix as well as composite. Results showed that addition of CNTs lead to increased hardness of the material and maximum hardness was found for 1 wt. % CNTs. So this composition was selected for detailed wear analysis. Pin-on-disk wear tests were conducted for the monolithic Al6061 and the composite at a constant speed of 0.5 m/s with varying load from 5 N to 30 N under dry sliding conditions using AISI 4140 steel disk as a counterface. The composite displayed lower wear rate and friction coefficient at lower levels of applied stress (0.175 to 0.525 MPa). Under higher stresses (0.700 to 1.050 MPa), the increased brittleness and porosity of the composite caused severe fracturing and delamination resulting in excessive wear rate and friction coefficient for the composite as compared to monolithic Al6061. The transition from mild to severe wear regime in composite occurred also at lower stress as compared to monolith. Analysis of the worn surfaces revealed abrasion as the dominant wear mechanism for both the materials at lower stresses. At higher stress levels, adhesion was found to be dominant in monolithic Al6061 whereas in composite, excessive sub-surface fracturing and delamination was mainly observed.

Influences of post weld heat treatment on tensile strength and microstructure characteristics of friction stir welded butt joints of AA2014-T6 aluminum alloy

NASA Astrophysics Data System (ADS)

Rajendran, C.; Srinivasan, K.; Balasubramanian, V.; Balaji, H.; Selvaraj, P.

2016-08-01

Friction stir welded (FSWed) joints of aluminum alloys exhibited a hardness drop in both the advancing side (AS) and retreating side (RS) of the thermo-mechanically affected zone (TMAZ) due to the thermal cycle involved in the FSW process. In this investigation, an attempt has been made to overcome this problem by post weld heat treatment (PWHT) methods. FSW butt (FSWB) joints of Al-Cu (AA2014-T6) alloy were PWHT by two methods such as simple artificial aging (AA) and solution treatment followed by artificial aging (STA). Of these two treatments, STA was found to be more beneficial than the simple aging treatment to improve the tensile properties of the FSW joints of AA2014 aluminum alloy.

Acoustic emission from a solidifying aluminum-lithium alloy

NASA Technical Reports Server (NTRS)

Henkel, D. P.; Wood, J. D.

1992-01-01

Physical phenomena associated with the solidification of an AA2090 Al-Li alloy have been characterized by AE methods. Repeatable patterns of AE activity as a function of solidification time are recorded and explained for ultrahigh-purity (UHP) aluminum and an Al-4.7 wt pct Cu binary alloy, in addition to the AA2090 Al-Li alloy, by the complementary utilization of thermal, AE, and metallographic methods. One result shows that the solidification of UHP aluminum produces one discrete period of high AE activity as the last 10 percent of solid forms.

Comparison of dry sliding wear and friction behavior of Al6061/SiC PMMC with Al6061 alloy

NASA Astrophysics Data System (ADS)

Murthy, A. G. Shankara; Mehta, N. K.; Kumar, Pradeep

2018-04-01

Dry sliding wear and friction behavior tests were conducted on Al6061 alloy and Al6061/SiC particle reinforced metal matrix composites (PMMCs) reinforced with fine particles of 5, 10 and 15 µm size having 5,7.5 and 10% weight content fabricated by stir-casting route. Cylindrical sample pins produced as per ASTM standard were tested for various parameters like SiC size, weight content, load and sliding distance affecting the wear rate or resistance and friction. Results indicated that Al6061/SiCp composites exhibited good wear resistance compared to Al6061 alloy for the tested parameters.

Four-point-bend fatigue of AA 2026 aluminum alloys

NASA Astrophysics Data System (ADS)

Li, J. X.; Zhai, T.; Garratt, M. D.; Bray, G. H.

2005-09-01

High-cycle fatigue tests were carried out on a newly developed high-strength AA 2026 Al alloy, which was in the form of extrusion bars with square and rectangular cross sections, using a self-aligning four-point-bend rig at room temperature, 15 Hz, and R = 0.1, in lab air. The fatigue strength of the square and rectangular bars was measured to be 85 and 90 pct of their yield strength, respectively, more than twice that of the predecessor to the 2026 alloy (the AA 2024 Al alloy). Fatigue cracks were found to be always initiated at large Θ' (Al7Cu2(Fe,Mn)) particles and to propagate predominantly in a crystallographic mode in the AA 2026 alloy. The fatigue fractographies of the square and rectangular extrusion bars were found to be markedly different, due to their different grain structures (fibril and layered, respectively). Fracture steps on the crack face were found in both of these extrusion bars. Since the 2026 alloy was purer in terms of Fe and Si content, it contained much less coarse particles than in a 2024 alloy. This partially accounted for the superior fatigue strength of the 2026 alloy.

Primary and secondary creep in aluminum alloys as a solid state transformation

NASA Astrophysics Data System (ADS)

Fernández, R.; Bruno, G.; González-Doncel, G.

2016-08-01

Despite the massive literature and the efforts devoted to understand the creep behavior of aluminum alloys, a full description of this phenomenon on the basis of microstructural parameters and experimental conditions is, at present, still missing. The analysis of creep is typically carried out in terms of the so-called steady or secondary creep regime. The present work offers an alternative view of the creep behavior based on the Orowan dislocation dynamics. Our approach considers primary and secondary creep together as solid state isothermal transformations, similar to recrystallization or precipitation phenomena. In this frame, it is shown that the Johnson-Mehl-Avrami-Kolmogorov equation, typically used to analyze these transformations, can also be employed to explain creep deformation. The description is fully compatible with present (empirical) models of steady state creep. We used creep curves of commercially pure Al and ingot AA6061 alloy at different temperatures and stresses to validate the proposed model.

Microstructure Evolution and Mechanical Properties of High-Speed Friction Stir Welded Aluminum Alloy Thin Plate Joints

NASA Astrophysics Data System (ADS)

Liu, Fenjun; Fu, Li; Chen, Haiyan

2018-06-01

Sound friction stir welded (FSW) joints of 6061-T6 aluminum alloy sheets with an 0.8 mm thickness were obtained at conventional speed (2000 rpm, 300 mm/min) and high speed (11,000 rpm, 1500 mm/min). The recrystallization mechanism, precipitate evolution, mechanical properties and fracture behavior were investigated in detail. Microstructure analyses revealed that the grain structure evolution in the nugget zone (NZ) was dominated by continuous dynamic recrystallization. In the process of FSW, high speed facilitates the formation of finer equiaxed recrystallized grains, higher density of dislocations and substructures, and a larger number of precipitates in the NZ compared to the conventional speed, which further significantly improves the hardness and tensile strength of the joints. The maximum tensile strength was obtained with 292.6 MPa, 83.2% for the 6061-T6 aluminum alloy and 122.6% for the conventional-speed FSW joints. This work provides an effective method for preparing FSW aluminum alloy thin plate joints with excellent mechanical properties.

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.

Studies on post weld heat treatment of dissimilar aluminum alloys by laser beam welding technique

NASA Astrophysics Data System (ADS)

Srinivas, B.; Krishna, N. Murali; Cheepu, Muralimohan; Sivaprasad, K.; Muthupandi, V.

2018-03-01

The present study mainly focuses on post weld heat treatment (PWHT) of AA5083 and AA6061 alloys by joining these using laser beam welding at three different laser power and two different beam spot sizes and three different welding speeds. Effects of these parameters on microstructural and mechanical properties like hardness, tensile strength were studied at PWHT condition and significant changes had been observed. The PWHT used was artificial aging technique. The microstructural observations revealed that there was a appreciable changes were taken place in the grain size. The microhardness observations proven that the change in the hardness profile in AA6061 was appreciable than in the AA5083. The tensile strength of 246 MPa was recorded as highest. The fractured surfaces observed are predominantly ductile in nature.

Diffusion bonded boron/aluminum spar-shell fan blade

NASA Technical Reports Server (NTRS)

Carlson, C. E. K.; Cutler, J. L.; Fisher, W. J.; Memmott, J. V. W.

1980-01-01

Design and process development tasks intended to demonstrate composite blade application in large high by-pass ratio turbofan engines are described. Studies on a 3.0 aspect radio space and shell construction fan blade indicate a potential weight savings for a first stage fan rotor of 39% when a hollow titanium spar is employed. An alternate design which featured substantial blade internal volume filled with titanium honeycomb inserts achieved a 14% potential weight savings over the B/M rotor system. This second configuration requires a smaller development effort and entails less risk to translate a design into a successful product. The feasibility of metal joining large subsonic spar and shell fan blades was demonstrated. Initial aluminum alloy screening indicates a distinct preference for AA6061 aluminum alloy for use as a joint material. The simulated airfoil pressings established the necessity of rigid air surfaces when joining materials of different compressive rigidities. The two aluminum alloy matrix choices both were successfully formed into blade shells.

Effect of Scandium on the Interaction of Concurrent Precipitation and Recrystallization in Commercial AA3003 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Tu, Yiyou; Qian, Huan; Zhou, Xuefeng; Jiang, Jianqing

2014-04-01

In the current study, the effect of Sc addition on the interaction of concurrent precipitation and recrystallization in commercial AA3003 aluminum alloy was investigated using optical microscopy, scanning electron microscopy, and transmission electron microscopy. In case of AA3003 alloy, which was cold rolled to a true strain of 2.20 and heated at a heating rate of 150 K/s, the onset of precipitation and ending of recrystallization are signified by the critical temperature, T C ~740 K (467 °C). There is a change in the shape of the recrystallized grains from pancake-like to equiaxed shape, as the annealing temperature increases greater than T C. In case of AA3003 alloy microalloyed with 0.4 wt pct of Sc, the high no. density precipitation of coherent Al3Sc precipitates always occurs before recrystallization because of the small nucleation barrier and high rate of decomposition. This leads to extremely coarse pancake-like recrystallization grains with high fraction of low-angle grain boundaries in the entire annealing temperature range, even at a high brazing temperature of 883 K (610 °C).

On the Role of Processing Parameters in Producing Recycled Aluminum AA6061 Based Metal Matrix Composite (MMC-AlR) Prepared Using Hot Press Forging (HPF) Process.

PubMed

Ahmad, Azlan; Lajis, Mohd Amri; Yusuf, Nur Kamilah

2017-09-19

Solid-state recycling, which involves the direct recycling of scrap metal into bulk material using severe plastic deformation, has emerged as a potential alternative to the conventional remelting and recycling techniques. Hot press forging has been identified as a sustainable direct recycling technique that has fewer steps and maintains excellent material performance. An experimental investigation was conducted to explore the hardness and density of a recycled aluminum-based metal matrix composite by varying operating temperature and holding time. A mixture of recycled aluminum, AA6061, and aluminum oxide were simultaneously heated to 430, 480, and 530 °C and forged for 60, 90, and 120 min. We found a positive increase in microhardness and density for all composites. The hardness increased approximately 33.85%, while density improved by about 15.25% whenever the temperature or the holding time were increased. Based on qualitative analysis, the composite endures substantial plastic deformation due to the presence of hardness properties due to the aluminum oxide embedded in the aluminum matrix. These increases were significantly affected by the operating temperature; the holding time also had a subordinate role in enhancing the metal matrix composite properties. Furthermore, in an effort to curb the shortage of primary resources, this study reviewed the promising performance of secondary resources produced by using recycled aluminum and aluminum oxide as the base matrix and reinforcement constituent, respectively. This study is an outline for machining practitioners and the manufacturing industry to help increase industry sustainability with the aim of preserving the Earth for our community in the future.

On the Role of Processing Parameters in Producing Recycled Aluminum AA6061 Based Metal Matrix Composite (MMC-AlR) Prepared Using Hot Press Forging (HPF) Process

PubMed Central

Ahmad, Azlan; Lajis, Mohd Amri

2017-01-01

Solid-state recycling, which involves the direct recycling of scrap metal into bulk material using severe plastic deformation, has emerged as a potential alternative to the conventional remelting and recycling techniques. Hot press forging has been identified as a sustainable direct recycling technique that has fewer steps and maintains excellent material performance. An experimental investigation was conducted to explore the hardness and density of a recycled aluminum-based metal matrix composite by varying operating temperature and holding time. A mixture of recycled aluminum, AA6061, and aluminum oxide were simultaneously heated to 430, 480, and 530 °C and forged for 60, 90, and 120 min. We found a positive increase in microhardness and density for all composites. The hardness increased approximately 33.85%, while density improved by about 15.25% whenever the temperature or the holding time were increased. Based on qualitative analysis, the composite endures substantial plastic deformation due to the presence of hardness properties due to the aluminum oxide embedded in the aluminum matrix. These increases were significantly affected by the operating temperature; the holding time also had a subordinate role in enhancing the metal matrix composite properties. Furthermore, in an effort to curb the shortage of primary resources, this study reviewed the promising performance of secondary resources produced by using recycled aluminum and aluminum oxide as the base matrix and reinforcement constituent, respectively. This study is an outline for machining practitioners and the manufacturing industry to help increase industry sustainability with the aim of preserving the Earth for our community in the future. PMID:28925963

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.

Nugget Structure Evolution with Rotation Speed for High-Rotation-Speed Friction-Stir-Welded 6061 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Zhang, H. J.; Wang, M.; Zhu, Z.; Zhang, X.; Yu, T.; Wu, Z. Q.

2018-03-01

High-rotation-speed friction stir welding (HRS-FSW) is a promising technique to reduce the welding loads during FSW and thus facilitates the application of FSW for in situ fabrication and repair. In this study, 6061 aluminum alloy was friction stir welded at high-rotation speeds ranging from 3000 to 7000 rpm at a fixed welding speed of 50 mm/min, and the effects of rotation speed on the nugget zone macro- and microstructures were investigated in detail in order to illuminate the process features. Temperature measurements during HRS-FSW indicated that the peak temperature did not increase consistently with rotation speed; instead, it dropped remarkably at 5000 rpm because of the lowering of material shear stress. The nugget size first increased with rotation speed until 5000 rpm and then decreased due to the change of the dominant tool/workpiece contact condition from sticking to sliding. At the rotation speed of 5000 rpm, where the weld material experienced weaker thermal effect and higher-strain-rate plastic deformation, the nugget exhibited relatively small grain size, large textural intensity, and high dislocation density. Consequently, the joint showed superior nugget hardness and simultaneously a slightly low tensile ductility.

Gas tungsten arc welding of aluminum alloys 6XXX. Welding procedure specification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wodtke, C.H.; Frizzell, D.R.; Plunkett, W.A.

1985-08-01

Procedure WPS-1003 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for gas tungsten arc welding of aluminum alloys 6061 and 6063 (P-23), in thickness range 0.035 to 0.516 in.; filler metal is ER4043 (F-23) or ER5356 (F-22); shielding gas is argon.

Modeling the microstructural changes during hot tandem rolling of AA5 XXX aluminum alloys: Part I. Microstructural evolution

NASA Astrophysics Data System (ADS)

Wells, M. A.; Samarasekera, I. V.; Brimacombe, J. K.; Hawbolt, E. B.; Lloyd, D. J.

1998-06-01

A comprehensive mathematical model of the hot tandem rolling process for aluminum alloys has been developed. Reflecting the complex thermomechanical and microstructural changes effected in the alloys during rolling, the model incorporated heat flow, plastic deformation, kinetics of static recrystallization, final recrystallized grain size, and texture evolution. The results of this microstructural engineering study, combining computer modeling, laboratory tests, and industrial measurements, are presented in three parts. In this Part I, laboratory measurements of static recrystallization kinetics and final recrystallized grain size are described for AA5182 and AA5052 aluminum alloys and expressed quantitatively by semiempirical equations. In Part II, laboratory measurements of the texture evolution during static recrystallization are described for each of the alloys and expressed mathematically using a modified form of the Avrami equation. Finally, Part III of this article describes the development of an overall mathematical model for an industrial aluminum hot tandem rolling process which incorporates the microstructure and texture equations developed and the model validation using industrial data. The laboratory measurements for the microstructural evolution were carried out using industrially rolled material and a state-of-the-art plane strain compression tester at Alcan International. Each sample was given a single deformation and heat treated in a salt bath at 400 °C for various lengths of time to effect different levels of recrystallization in the samples. The range of hot-working conditions used for the laboratory study was chosen to represent conditions typically seen in industrial aluminum hot tandem rolling processes, i.e., deformation temperatures of 350 °C to 500 °C, strain rates of 0.5 to 100 seconds and total strains of 0.5 to 2.0. The semiempirical equations developed indicated that both the recrystallization kinetics and the final recrystallized

Corrosion behavior of ultrafine-grained AA2024 aluminum alloy produced by cryorolling

NASA Astrophysics Data System (ADS)

Laxman Mani Kanta, P.; Srivastava, V. C.; Venkateswarlu, K.; Paswan, Sharma; Mahato, B.; Das, Goutam; Sivaprasad, K.; Krishna, K. Gopala

2017-11-01

The objectives of this study were to produce ultrafine-grained (UFG) AA2024 aluminum alloy by cryorolling followed by aging and to evaluate its corrosion behavior. Solutionized samples were cryorolled to 85% reduction in thickness. Subsequent aging resulted in a UFG structure with finer precipitates of Al2CuMg in the cryorolled alloy. The (1) solutionized and (2) solutionized and cryorolled samples were uniformly aged at 160°C/24 h and were designated as CGPA and CRPA, respectively; these samples were subsequently subjected to corrosion studies. Potentiodynamic polarization studies in 3.5wt% NaCl solution indicated an increase in corrosion potential and a decrease in corrosion current density for CRPA compared to CGPA. In the case of CRPA, electrochemical impedance spectroscopic studies indicated the presence of two complex passive oxide layers with a higher charge transfer resistance and lower mass loss during intergranular corrosion tests. The improved corrosion resistance of CRPA was mainly attributed to its UFG structure, uniform distribution of fine precipitates, and absence of coarse grain-boundary precipitation and associated precipitate-free zones as compared with the CGPA alloy.

Effect of pin tool design on the material flow of dissimilar AA7075-AA6061 friction stir welds

NASA Astrophysics Data System (ADS)

Hasan, Mohammed M.; Ishak, M.; Rejab, M. R. M.

2017-10-01

Tool design is the most influential aspect in the friction stir welding (FSW) technology. Influence of pin tool geometry on material flow pattern are studied in this work during the FSW of dissimilar AA7075 and AA6061 aluminium alloys. Three truncated pin tool profiles (threaded, threaded with single flat, and unthreaded with single flat) were used to prepare the weldments. The workpieces were joined using a custom-made clamping system under 1100 rpm of spindle speed, 300 mm/min of traverse rate and 3° of tilt angle. The metallographic analysis showed that defect-free welds can be produced using the three pin tools with significant changes in the mixing stir zone structure. The results declared that the introducing of the flat on the cone of the probe deviates the pattern of the onion rings without changing the chemical composition of the created layers. This in turn improves the hardness distribution and tensile strength of the welded joint. It was also noted that both heat affected zone (HAZ) and thermal-mechanical affected zone (TMAZ) are similar in composition to their corresponding base materials (BM).

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.

Effect of temperature on the anodizing process of aluminum alloy AA 5052

NASA Astrophysics Data System (ADS)

Theohari, S.; Kontogeorgou, Ch.

2013-11-01

The effect of temperature (10-40 °C) during the anodizing process of AA 5052 for 40 min in 175 g/L sulfuric acid solution at constant voltage (15 V) was studied in comparison with pure aluminum. The incorporated magnesium species in the barrier layer result in the further increase of the minimum current density passed during anodizing, as the temperature increases, by about 42% up to 30 °C and then by 12% up to 40 °C. Then during the anodizing process for 40 min a blocking effect on oxide film growth was gradually observed as the temperature increased until 30 °C. The results of EDAX analysis on thick films reveal that the mean amount of the magnesium species inside the film is about 50-70% less than that in the bulk alloy, while it is higher at certain locations adjacent to the film surface at 30 °C. The increase of anodizing temperature does not influence the porosity of thin films (formed for short times) on pure aluminum, while it reduces it on the alloy. At 40 °C the above mentioned blocking effects disappear. It means that the presence of magnesium species causes an impediment to the effect of temperature on iss, on the film thickness and on the porosity of thin films, only under conditions where film growth takes place without significant loss of the anodizing charge to side reactions.

Heat-Affected Zone Liquation Cracking Resistance of Friction Stir Processed Aluminum-Copper Alloy AA 2219

NASA Astrophysics Data System (ADS)

Karthik, G. M.; Janaki Ram, G. D.; Kottada, Ravi Sankar

2017-04-01

In the current work, the effect of friction stir processing on heat-affected zone (HAZ) liquation cracking resistance of aluminum-copper alloy AA 2219 was evaluated. In Gleeble hot-ductility tests and longitudinal Varestraint tests, the FSPed material, despite its very fine dynamically recrystallized equiaxed grain structure, showed considerably higher susceptibility to HAZ liquation cracking when compared to the base material. Detailed microstructural studies showed that the increased cracking susceptibility of the FSPed material is due to (i) increase in the amount of liquating θ phase (equilibrium Al2Cu) and (ii) increase in the population of grain boundary θ particles. An important learning from the current work is that, in certain materials like alloy 2219, the use of FSP as a pretreatment to fusion welding can be counterproductive.

The Solidification Behavior of AA2618 Aluminum Alloy and the Influence of Cooling Rate

PubMed Central

Liu, Yulin; Liu, Ming; Luo, Lei; Wang, Jijie; Liu, Chunzhong

2014-01-01

In AA2618 aluminum alloy, the iron- and nickel-rich intermetallics formed during solidification are of great effect on the mechanical properties of the alloy at both room temperature and elevated temperatures. However, the solidification behavior of the alloy and the formation mechanism of the intermetallics during solidification of the alloy are not clear. This research fills the gap and contributes to understanding the intermetallic of the alloy. The results showed that cooling rate was of great influence on the formation of the intermetallics. Under the condition of slow cooling, the as-cast microstructures of the alloy were complex with many coarse eutectic compounds including Al9FeNi, Al7(CuNi)5, Si, Al2Cu and Al2CuMg. The phase Al9FeNi was the dominant intermetallic compound, which precipitated at the earlier stage of the solidification by eutectic reaction L → α-Al + Al9FeNi. Increasing the cooling rate would suppress the formation of the coarse eutectic intermetallics. Under the condition of near-rapid cooling, the as-cast microstructures of the alloy consisted of metastable intermetallics Al9FeNi and Al2Cu; the equilibrium eutectic compounds were suppressed. This research concluded that intermetallics could be refined to a great extent by near-rapid cooling. PMID:28788281

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.

Effects of thermal cycling on graphie-fiber-reinforced 6061 aluminum

NASA Technical Reports Server (NTRS)

Dries, G. A.; Tompkins, S. S.

1986-01-01

Graphite-reinforced aluminum alloy metal-matrix composites are among materials being considered for structural components in dimensionally stable space structures. This application requires materials with low values of thermal expansions and high specific stiffnesses. They must remain stable during exposures to the space environment for periods extending to 20 years. The effects of thermal cycling on the thermal expansion behavior and mechanical properties of Thornel P100 graphite 6061 aluminum composites, as fabricated and after thermal processing to eliminate thermal strain hysteresis, have been investigated. Two groups of composites were studied: one was fabricated by hot roll bonding and the other by diffusion bonding. Processing significantly reduced strain hysteresis during thermal cycling in both groups and improved the ultimate tensile strength and modulus in the diffusion-bonded composites. Thermal cycling stabilized the as-fabricated composites by reducing the residual fabrication stress and increased the matrix strength by metallurgical aging. Thermal expansion behavior of both groups after processing was insensitive to thermal cycling. Data scatter was too large to determine effects of thermal cycling on the mechanical properties. The primary effects of processing and thermal cycling can be attributed to changes in the metallurgical condition and stress state of the matrix.

Frictional conditions between alloy AA6060 aluminium and tool steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wideroee, Fredrik; Welo, Torgeir

The frictional conditions in the new process of screw extrusion of aluminium have been investigated. The contact behaviour between the aluminum alloy and the tool steel in the extruder is vital for understanding the extrusion process. Using a compressive-rotational method for frictional measurements the conditions for unlubricated sticking friction between aluminum alloy AA6060 and tool steel at different combinations of temperatures and pressures have been investigated. In this method the samples in the form of disks are put under hydrostatic pressure while simultaneously being rotated at one end. Pins made from contrast material have been inserted into the samples tomore » measure the deformation introduced. This approach along with 3D simulations form a method for determining the frictional conditions. The paper describes the test method and the results. It was found that the necessary pressure for sticking to occur between the aluminum AA6060 and the different parts of the extruder is heavily influenced by the temperature.« less

Microstructure dependence of dynamic fracture and yielding in aluminum and an aluminum alloy at strain rates of 2 × 106 s-1 and faster

NASA Astrophysics Data System (ADS)

Dalton, D. A.; Worthington, D. L.; Sherek, P. A.; Pedrazas, N. A.; Quevedo, H. J.; Bernstein, A. C.; Rambo, P.; Schwarz, J.; Edens, A.; Geissel, M.; Smith, I. C.; Taleff, E. M.; Ditmire, T.

2011-11-01

Experiments investigating fracture and resistance to plastic deformation at fast strain rates (>106 s-1) were performed via laser ablation on thin sheets of aluminum and aluminum alloys. Single crystal high purity aluminum (Al-HP) and a single crystal 1100 series aluminum alloy (AA1100) were prepared to investigate the role of impurity particles. Specimens of aluminum alloy +3 wt. % Mg (Al+3Mg) at three different grain sizes were also studied to determine the effect of grain size. In the present experiments, high purity aluminum (Al-HP) exhibited the highest spall strength over 1100 series aluminum alloy (AA1100) and Al+3Mg. Fracture characterization and particle analysis revealed that fracture was initiated in the presence of particles associated with impurity content in the AA1100 and at both grain boundaries and particles in Al+3Mg. The Al+3Mg specimens exhibited the greatest resistance to plastic deformation likely resulting from the presence of magnesium atoms. The Al-HP and AA1100, both lacking a strengthening element such as Mg, were found to have the same Hugoniot elastic limit (HEL) stress. Within the single crystal specimens, orientation effects on spall strength and HEL stress appear to be negligible. Although the fracture character shows a trend with grain size, no clear dependence of spall strength and HEL stress on grain size was measured for the Al+3Mg. Hydrodynamic simulations show how various strength and fracture models are insufficient to predict material behavior at fast strain rates, and a revised set of Tuler-Butcher coefficients for spall are proposed.

Effect of laser shot peening on precipitation hardened aluminum alloy 6061-T6 using low energy laser

NASA Astrophysics Data System (ADS)

Sathyajith, S.; Kalainathan, S.

2012-03-01

Mechanical properties of engineering material can be improved by introducing compressive residual stress on the material surface and refinement of their microstructure. Variety of mechanical process such as shot peening, water jet peening, ultrasonic peening, laser shot peening were developed in the last decades on this contrast. Among these, lasers shot peening emerged as a novel industrial treatment to improve the crack resistance of turbine blades and the stress corrosion cracking (SCC) of austenic stainless steel in power plants. In this study we successfully performed laser shot peening on precipitation hardened aluminum alloy 6061-T6 with low energy (300 mJ, 1064 nm) Nd:YAG laser using different pulse densities of 22 pulses/mm 2 and 32 pulses/mm 2. Residual stress evaluation based on X-ray diffraction sin 2 ψ method indicates a maximum of 190% percentage increase on surface compressive stress. Depth profile of micro-hardness shows the impact of laser generated shock wave up to 1.2 mm from the surface. Apart from that, the crystalline size and micro-strain on the laser shot peened surfaces have been investigated and compared with the unpeened surface using X-ray diffraction in conjunction with line broadening analysis through the Williamson-Hall plot.

Study of diffusion bond development in 6061 aluminum and its relationship to future high density fuels fabrication.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prokofiev, I.; Wiencek, T.; McGann, D.

1997-10-07

Powder metallurgy dispersions of uranium alloys and silicides in an aluminum matrix have been developed by the RERTR program as a new generation of proliferation-resistant fuels. Testing is done with miniplate-type fuel plates to simulate standard fuel with cladding and matrix in plate-type configurations. In order to seal the dispersion fuel plates, a diffusion bond must exist between the aluminum coverplates surrounding the fuel meat. Four different variations in the standard method for roll-bonding 6061 aluminum were studied. They included mechanical cleaning, addition of a getter material, modifications to the standard chemical etching, and welding methods. Aluminum test pieces weremore » subjected to a bend test after each rolling pass. Results, based on 400 samples, indicate that at least a 70% reduction in thickness is required to produce a diffusion bond using the standard rollbonding method versus a 60% reduction using the Type II method in which the assembly was welded 100% and contained open 9mm holes at frame corners.« less

Effect of Traverse and Rotational Speeds on the Tensile Behavior of the Underwater Dissimilar Friction Stir Welded Aluminum Alloys

NASA Astrophysics Data System (ADS)

Bijanrostami, Kh.; Barenji, R. Vatankhah; Hashemipour, M.

2017-02-01

The tensile behavior of the underwater dissimilar friction stir welded AA6061 and AA7075 aluminum alloy joints was investigated for the first time. For this aim, the joints were welded at different conditions and tensile test was conducted for measuring the strength and elongation of them. In addition, the microstructure of the joints was characterized by means of optical and transmission electron microscopes. Scanning electron microscope was used for fractography of the joints. Furthermore, the process parameters and tensile properties of the joints were correlated and optimized. The results revealed that the maximum tensile strength of 237.3 MPa and elongation of 41.2% could be obtained at a rotational speed 1853 rpm and a traverse speed of 50 mm/min. In comparison with the optimum condition, higher heat inputs caused grain growth and reduction in dislocation density and hence led to lower strength. The higher elongations for the joints welded at higher heat inputs were due to lower dislocation density inside the grains, which was consistent with a more ductile fracture of them.

Mechanical Properties of Aluminum-Based Dissimilar Alloy Joints by Power Beams, Arc and FSW Processes

NASA Astrophysics Data System (ADS)

Okubo, Michinori; Kon, Tomokuni; Abe, Nobuyuki

Dissimilar smart joints are useful. In this research, welded quality of dissimilar aluminum alloys of 3 mm thickness by various welding processes and process parameters have been investigated by hardness and tensile tests, and observation of imperfection and microstructure. Base metals used in this study are A1050-H24, A2017-T3, A5083-O, A6061-T6 and A7075-T651. Welding processes used are YAG laser beam, electron beam, metal inert gas arc, tungsten inert gas arc and friction stir welding. The properties of weld zones are affected by welding processes, welding parameters and combination of base metals. Properties of high strength aluminum alloy joints are improved by friction stir welding.

Corrosion of Graphite Aluminum Metal Matrix Composites

DTIC Science & Technology

1991-02-01

cathodic protection of G/AI MMCs resulted in overprotection 13. Overprotection resulted from a local increase in pH near cathodic sites during...34Cathodic Overprotection of SiC/6061-T6 and G/6061- T6 Aluminum Alloy Metal Matrix Composites," Scripta Metallurgica, 22 (1988) 413-418. 14. R

Effects Of Welding On The Fatigue Behaviour Of Commercial Aluminum AA-1100 Joints

NASA Astrophysics Data System (ADS)

Uthayakumar, M.; Balasubramanian, V.; Rani, Ahmad Majdi Abdul; Hadzima, Branislav

2018-04-01

Friction Stir Welding (FSW) is an budding solid state welding process, which is frequently used for joining aluminum alloys where materials can be joined without melt and recast. Therefore, when welding alloys through FSW the phase transformations occurs will be in the solid state form. The present work is aimed in evaluating the fatigue life of friction stir welded commercial grade aluminum alloy joints. The commercial grade AA1100 aluminum alloy of 12mm thickness plate is welded and the specimens are tested using a rotary beam fatigue testing machine at different stress levels. The stress versus number of cycles (S-N) curves was plotted using the data points. The Fatigue life of tungsten inert gas (TIG) and metal inert gas (MIG) welded joints was compared. The fatigue life of the weld joints was interrelated with the tensile properties, microstructure and micro hardness properties. The effects of the notches and welding processes are evaluated and reported.

Microstructural Characterization of the U-9.1Mo Fuel/AA6061 Cladding Interface in Friction-Bonded Monolithic Fuel Plates Irradiated in the RERTR-6 Experiment

DOE PAGES

Keiser, Dennis D.; Jue, Jan-Fong; Miller, Brandon; ...

2015-09-03

Low-enrichment (U-235 < 20%) U-Mo monolithic fuel is being developed for use in research and test reactors. The earliest design for this fuel that was investigated via reactor testing was comprised of a nominally U-10Mo fuel foil encased in AA6061 (Al-6061) cladding. For a fuel design to be deemed adequate for final use in a reactor, it must maintain dimensional stability and retain fission products throughout irradiation, which means that there must be good integrity at the fuel foil/cladding interface. To investigate the nature of the fuel/cladding interface for this fuel type after irradiation, fuel plates that were tested inmore » INL's Advanced Test Reactor (ATR) were subsequently characterized using optical metallography, scanning electron microscopy, and transmission electron microscopy. Results of this characterization showed that the fuel/cladding interaction layers present at the U-Mo fuel/AA6061 cladding interface after fabrication became amorphous during irradiation. Up to two main interaction layers, based on composition, could be found at the fuel/cladding interface, depending on location. After irradiation, an Al-rich layer contained very few fission gas bubbles, but did exhibit Xe enrichment near the AA6061 cladding interface. Another layer, which contained more Si, had more observable fission gas bubbles. Adjacent to the AA6061 cladding were Mg-rich precipitates, which was in close proximity to the region where Xe is observed to be enriched. In samples produced using a focused ion beam at the interaction zone/AA6061 cladding interface were possible indications of porosity/debonding, which suggested that the interface in this location is relatively weak.« less

Replacement of steel parts with extruded aluminum alloys in an automobile

NASA Astrophysics Data System (ADS)

Daggula, Manikantha Reddy

Over the past years, vehicle emissions have shown a negative impact on environment and human health. A new strategy has been used by automakers to reduce a vehicle's weight which significantly reduce fuel consumption and C02 emissions. A very light car consumes very less fuel as it needs to overcome less inertia, decreasing the required power to movie the vehicle. Reducing weight is the easiest way to increase fuel economy and making it by just 10% can increase its efficiency 6 to 8 percent. For a normal scale 80% of vehicles weight is shared among chassis, power train and other exterior components. Almost 60% of the vehicles weight is comprised of steel and the remaining is with cast and extruded aluminum and magnesium alloys. Our main aim is to look for the parts like Fuel tank holder, Fuel filler neck, Turbo inlet assembly, and Brake lines, Dash board frame which are made from steel and replace them with extruded aluminum alloys, to analyze a conventional rear wheel aluminum drive shaft and replace it with a new design and with a new aluminum alloy. The current project involves dismantling an automobile and looking for feasible steel parts and making samples, analyzing the hardness of the samples. These parts are optimally analyzed using Ansys Finite element analysis tool, these parts are subjected to the constraints such as three-point bending, tensile testing, hydrostatic pressure and also torsional stress action on the drive shaft, the deformation and stress are observed in these parts. The results show the current steel parts can be replaced with 3000 series aluminum alloy and the drive shaft can be replaced with new design with 6061-T6 Al-alloy which decreases 25% of the shaft weight.

Microscopic Observation of the Side Surface of Dynamically-Tensile-Fractured 6061-T6 and 2219-T87 Aluminum Alloys with Pre-Fatigue

NASA Astrophysics Data System (ADS)

Itabashi, Masaaki; Nakajima, Shigeru; Fukuda, Hiroshi

After unexpected failure of metallic structure, microscopic investigation will be performed. Generally, such an investigation is limited to search striation pattern with a SEM (scanning electron microscope). But, when the cause of the failure was not severe repeated stress, this investigation is ineffective. In this paper, new microscopic observation technique is proposed to detect low cycle fatigue-impact tensile loading history. Al alloys, 6061-T6 and 2219-T87, were fractured in dynamic tension, after severe pre-fatigue. The side surface of the fractured specimens was observed with a SEM. Neighboring fractured surface, many opened cracks on the side surface have been generated. For each specimen, the number of the cracks was counted together with information of individual sizes and geometric features. For 6061-T6 alloy specimen with the pre-fatigue, the number of the cracks is greater than that for the specimen without the pre-fatigue. For 2219-T87 alloy, the same tendency can be found after a certain screening of the crack counting. Therefore, the crack counting technique may be useful to detect the existence of the pre-fatigue from the dynamically fractured specimen surface.

Microstructure and Mechanical Property Change During FSW and GTAW of Al6061 Alloy

NASA Astrophysics Data System (ADS)

Fahimpour, V.; Sadrnezhaad, S. K.; Karimzadeh, F.

2013-05-01

The variation of morphology and mechanical properties of Al6061 automotive aluminum alloy due to friction stir welding (FSW) and gas tungsten arc welding (GTAW) was investigated by optical metallography, scanning electron microscopy, microhardness measurement, X-ray diffraction, tensile testing, and fractography. The center-line dendrite emergence and microhardness reduction in the heat-affected zone were observed in the GTAW process. Although similar microhardness reduction with respect to the base metal was observed in the FSW samples, higher HVs were obtained for the FSW rather than the GTAW process at almost all heat-affected locations. Ultimate tensile strengths of the FSW and the GTAW samples in the transverse direction were ~0.57 and ~0.35 of the base metal, respectively. Post-weld aging improved the strength, but reduced the ductility of the welding.

Measurement and analysis of applied power, forces and material response in friction stir welding of aluminum alloy 6061

NASA Astrophysics Data System (ADS)

Avila, Ricardo E.

The process of Friction Stir Welding (FSW) 6061 aluminum alloy is investigated, with focus on the forces and power being applied in the process and the material response. The main objective is to relate measurements of the forces and power applied in the process with mechanical properties of the material during the dynamic process, based on mathematical modeling and aided by computer simulations, using the LS-DYNA software for finite element modeling. Results of measurements of applied forces and power are presented. The result obtained for applied power is used in the construction of a mechanical variational model of FSW, in which minimization of a functional for the applied torque is sought, leading to an expression for shear stress in the material. The computer simulations are performed by application of the Smoothed Particle Hydrodynamics (SPH) method, in which no structured finite element mesh is used to construct a spatial discretization of the model. The current implementation of SPH in LS-DYNA allows a structural solution using a plastic kinematic material model. This work produces information useful to improve understanding of the material flow in the process, and thus adds to current knowledge about the behavior of materials under processes of severe plastic deformation, particularly those processes in which deformation occurs mainly by application of shear stress, aided by thermoplastic strain localization and dynamic recrystallization.

Structure-composition-property relationships in 5xxx series aluminum alloys

NASA Astrophysics Data System (ADS)

Unocic, Kinga A.

Al-Mg alloys are well suited for marine applications due to their low density, ease of fabrication, structural durability, and most notably resistance to corrosion. The purpose of this study is to investigate the effects of alloying additions, mechanical processing and heat treatments on the development of grain boundary phases that have an effect on intergranular corrosion (IGC). Cu, Zn, and Si modified compositions of AA5083 were produced that were subjected to a low and high degree of cold work and various heat treatments. ASTM G67 (NAMLT) intergranular corrosion testing and detailed microstructural characterization for various alloys was carried out. An optimal composition and processing condition that yielded the best intergranular corrosion resistant material was identified based on the ASTM G67 test screening. Further, the outstanding modified AA5083 was selected for further microstructural analysis. This particular alloy with has a magnesium level high enough to make it susceptible to intergranular corrosion is very resistant to IGC. It was found that development of the appropriate sub-structure with some Cu, Si and Zn resulted in a material very resistant to IGC. Formation of many sinks, provided by sub-boundaries, within microstructure is very beneficial since it produces a relatively uniform distribution of Mg in the grain interiors, and this can suppress sensitization of this alloy very successfully. This is a very promising rote for the production of high-strength, and corrosion resistant aluminum alloys. Additionally in this study, TEM sample preparation become very crucial step in grain boundary phase investigation. Focus Ion Beam (FIB) milling was used as a primary TEM sample preparation technique because it enables to extract the samples from desired and very specific locations without dissolving grain boundary phases as it was in conventional electropolishing method. However, other issues specifically relevant to FIB milling of aluminum alloys

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.

Microstructure and texture of a nano-grained complex Al alloy fabricated by accumulative roll-bonding of dissimilar Al alloys.

PubMed

Lee, Seong-Hee; Jeon, Jae-Yeol; Lee, Kwang-Jin

2013-01-01

An ultrafine grain (UFG) complex lamella aluminum alloy sheet was successfully fabricated by ARB process using AA1050 and AA6061. The lamella thickness of the alloy became thinner and elongated to the rolling direction with increasing the number of ARB cycles. By TEM observation, it is revealed that the aspect ratio of UFGs formed by ARB became smaller with increasing the number of ARB cycles. In addition, the effect of ARB process on the development of deformation texture at the quarter thickness of ARB-processed sheets was clarified. ARB process leaded to the formation of the rolling texture with shear texture and weak cube orientation. The subdivision of the grains to the rolling direction began to occur after 3 cycles of the ARB, resulting in formation of ultrafine grains with small aspect ratio. After 5 cycles, the ultrafine grained structure with the average grain diameter of 560 nm develops in almost whole regions of the sample.

Effect of Backing Plate Thermal Property on Friction Stir Welding of 25-mm-Thick AA6061

NASA Astrophysics Data System (ADS)

Upadhyay, Piyush; Reynolds, Anthony

2014-04-01

By using backing plates made out of materials with widely varying thermal diffusivity this work seeks to elucidate the effects of the root side thermal boundary condition on weld process variables and resulting joint properties. Welds were made in 25.4-mm-thick AA6061 using ceramic, titanium, steel, and aluminum as backing plate (BP) material. Welds were also made using a "composite backing plate" consisting of longitudinal narrow strip of low diffusivity material at the center and two side plates of high diffusivity aluminum. Stir zone temperature during the welding was measured using two thermocouples spot welded at the core of the probe: one at the midplane height and another near the tip of the probe corresponding to the root of the weld. Steady state midplane probe temperatures for all the BPs used were found to be very similar. Near root peak temperature, however, varied significantly among weld made with different BPs all other things being equal. Whereas the near root and midplane temperature were the same in the case of ceramic backing plate, the root peak temperature was 318 K (45 °C) less than the midplane temperature in the case of aluminum BP. The trends of nugget hardness and grain size in through thickness direction were in agreement with the measured probe temperatures. Hardness and tensile test results show that the use of composite BP results in stronger joint compared to monolithic steel BP.

Stress Corrosion Cracking Study of Aluminum Alloys Using Electrochemical Noise Analysis

NASA Astrophysics Data System (ADS)

Rathod, R. C.; Sapate, S. G.; Raman, R.; Rathod, W. S.

2013-12-01

Stress corrosion cracking studies of aluminum alloys AA2219, AA8090, and AA5456 in heat-treated and non heat-treated condition were carried out using electrochemical noise technique with various applied stresses. Electrochemical noise time series data (corrosion potential vs. time) was obtained for the stressed tensile specimens in 3.5% NaCl aqueous solution at room temperature (27 °C). The values of drop in corrosion potential, total corrosion potential, mean corrosion potential, and hydrogen overpotential were evaluated from corrosion potential versus time series data. The electrochemical noise time series data was further analyzed with rescaled range ( R/ S) analysis proposed by Hurst to obtain the Hurst exponent. According to the results, higher values of the Hurst exponents with increased applied stresses showed more susceptibility to stress corrosion cracking as confirmed in case of alloy AA 2219 and AA8090.

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

PubMed

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

2011-07-01

Sensitization in 5XXX aluminum alloys is an insidious problem characterized by the gradual formation and growth of beta phase (Mg(2)Al(3)) at grain boundaries, which increases the susceptibility of alloys to intergranular corrosion (IGC) and intergranular stress-corrosion cracking (IGSCC). The degree of sensitization (DoS) is currently quantified by the ASTM G67 Nitric Acid Mass Loss Test, which is destructive and time consuming. A fast, reliable, and non-destructive method for rapid detection and the assessment of the condition of DoS in AA5XXX aluminum alloys in the field is highly desirable. In this paper, we describe a non-destructive method for measurements of DoS in aluminum alloys with an electromagnetic acoustic transducer (EMAT). AA5083 aluminum alloy samples were sensitized at 100°C with processing times varying from 7days to 30days. The DoS of sensitized samples was first quantified with the ASTM 67 test in the laboratory. Both ultrasonic velocity and attenuation in sensitized specimens were then measured using EMAT and the results were correlated with the DoS data. We found that the longitudinal wave velocity was almost a constant, independent of the sensitization, which suggests that the longitudinal wave can be used to determine the sample thickness. The shear wave velocity and especially the shear wave attenuation are sensitive to DoS. Relationships between DoS and the shear velocity, as well as the shear attenuation have been established. Finally, we performed the data mining to evaluate and improve the accuracy in the measurements of DoS in aluminum alloys with EMAT. Copyright © 2010 Elsevier B.V. All rights reserved.

Effect of Post Weld Heat Treatment on Corrosion Behavior of AA2014 Aluminum – Copper Alloy Electron Beam Welds

NASA Astrophysics Data System (ADS)

Venkata Ramana, V. S. N.; Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

2018-03-01

The present work pertains to the study of corrosion behavior of aluminum alloy electron beam welds. The aluminium alloy used in the present study is copper containing AA2014 alloy. Electron Beam Welding (EBW) was used to weld the alloys in annealed (O) condition. Microstructural changes across the welds were recorded and the effect of post weld heat treatment (PWHT) in T4 (Solutionized and naturally aged) condition on pitting corrosion resistance was studied. A software based PAR basic electrochemical system was used for potentio-dynamic polarization tests. From the study it is observed that weld in O condition is prone to more liquation than that of PWHT condition. This may be attributed to re-melting and solidification of excess eutectic present in the O condition of the base metal. It was also observed that slightly higher hardness values are recorded in O condition than that of PWHT condition. The pitting corrosion resistance of the PMZ/HAZ in PWHT condition is better than that of O condition. This is attributed to copper segregation at the grain boundaries of PMZ in O condition.

Long-term thermal degradation and alloying constituent effects on five boron/aluminum composites

NASA Technical Reports Server (NTRS)

Olsen, G. C.

1982-01-01

Thermal exposure effects on the properties of five boron/aluminum composite systems were experimentally investigated. The composite systems were 49 volume percent boron fibers (203 micron diameter) in aluminum-alloy matrices 1100 Al, 2024 Al, 3003 Al, 5052 Al, and 6061 Al. Specimens were thermally exposed up to 10,000 hours at 500 K and 590 K, up to 500 hours at 730 K, and up to 10,000 hours at 500 K and 590 K, up to 500 hours at 730 K, and up to 2000 thermal cycles between 200 K and 590 K. Composite longitudinal and transverse tensile strengths, longitudinal compression strength, and in-plane shear strength were determined. None of the systems was severely degraded by exposure at 590 K. The best performing system was B-2024 Al. Effects of matrix alloys on degradation mechanisms were experimentally investigated. Composite specimens and individual fibers were metallurgically analyzed with a scanning electron microscope and an electron microprobe to determine failure characteristics, chemical element distribution, and reaction layer morphology. Alloying constituents were found to be affect the composite degradation mechanisms as follows: alloys containing iron, but without manganese as a stabilizer, caused increased low-temperature degradation; alloys containing magnesium, iron, or manganese caused increased degradation; and alloys containing copper caused increased fiber strength.

Development and Validation of Capabilities to Measure Thermal Properties of Layered Monolithic U-Mo Alloy Plate-Type Fuel

NASA Astrophysics Data System (ADS)

Burkes, Douglas E.; Casella, Andrew M.; Buck, Edgar C.; Casella, Amanda J.; Edwards, Matthew K.; MacFarlan, Paul J.; Pool, Karl N.; Smith, Frances N.; Steen, Franciska H.

2014-07-01

The uranium-molybdenum (U-Mo) alloy in a monolithic form has been proposed as one fuel design capable of converting some of the world's highest power research reactors from the use of high enriched uranium to low enriched uranium. One aspect of the fuel development and qualification process is to demonstrate appropriate understanding of the thermal-conductivity behavior of the fuel system as a function of temperature and expected irradiation conditions. The purpose of this paper is to verify functionality of equipment installed in hot cells for eventual measurements on irradiated uranium-molybdenum (U-Mo) monolithic fuel specimens, refine procedures to operate the equipment, and validate models to extract the desired thermal properties. The results presented here demonstrate the adequacy of the equipment, procedures, and models that have been developed for this purpose based on measurements conducted on surrogate depleted uranium-molybdenum (DU-Mo) alloy samples containing a Zr diffusion barrier and clad in aluminum alloy 6061 (AA6061). The results are in excellent agreement with thermal property data reported in the literature for similar U-Mo alloys as a function of temperature.

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.

Parameter Design in Fusion Welding of AA 6061 Aluminium Alloy using Desirability Grey Relational Analysis (DGRA) Method

NASA Astrophysics Data System (ADS)

Adalarasan, R.; Santhanakumar, M.

2015-01-01

In the present work, yield strength, ultimate strength and micro-hardness of the lap joints formed with Al 6061 alloy sheets by using the processes of Tungsten Inert Gas (TIG) welding and Metal Inert Gas (MIG) welding were studied for various combinations of the welding parameters. The parameters taken for study include welding current, voltage, welding speed and inert gas flow rate. Taguchi's L9 orthogonal array was used to conduct the experiments and an integrated technique of desirability grey relational analysis was disclosed for optimizing the welding parameters. The ignored robustness in desirability approach is compensated by the grey relational approach to predict the optimal setting of input parameters for the TIG and MIG welding processes which were validated through the confirmation experiments.

Effect of in-situ formed Al3Ti particles on the microstructure and mechanical properties of 6061 Al alloy

NASA Astrophysics Data System (ADS)

Gupta, Rahul; Chaudhari, G. P.; Daniel, B. S. S.

2018-03-01

In this study, in situ Titanium-tri-aluminide (Al3Ti) particles reinforced Al 6061 alloy matrix composites were fabricated by the reaction of potassium hexafluorotitanate (K2TiF6) inorganic salt with molten Al 6061 alloy via liquid metallurgy route. The development of in-situ Al3Ti particles and their effects on the mechanical properties such as yield strength (YS), ductility, ultimate tensile strength (UTS) and hardness, and microstructure of Al 6061 alloy were studied. It was observed from the results that in-situ formed Al3Ti particles were blocky in morphology whose average size was around 2.6 ± 1.1 μm. Microstructure studies showed that grain size of Al matrix was reduced due to the nucleating effect of Al3Ti particles. It was observed from the mechanical properties analysis that when the volume fraction of Al3Ti particles was increased, the hardness, UTS and YS of the composites were also increased as compared to that of Al 6061 alloy. An improvement in ductility was observed with the dispersion of Al3Ti particles in base alloy which is contrary to many other composites.

Microstructural Characterization of the U-9.1Mo Fuel/AA6061 Cladding Interface in Friction-Bonded Monolithic Fuel Plates Irradiated in the RERTR-6 Experiment

NASA Astrophysics Data System (ADS)

Keiser, Dennis D.; Jue, Jan-Fong; Miller, Brandon; Gan, Jian; Robinson, Adam; Medvedev, Pavel; Madden, James; Wachs, Dan; Clark, Curtis; Meyer, Mitch

2015-09-01

Low-enrichment (235U < 20 pct) U-Mo monolithic fuel is being developed for use in research and test reactors. The earliest design for this fuel that was investigated via reactor testing consisted of a nominally U-10Mo fuel foil encased in AA6061 (Al-6061) cladding. For a fuel design to be deemed adequate for final use in a reactor, it must maintain dimensional stability and retain fission products throughout irradiation, which means that there must be good integrity at the fuel foil/cladding interface. To investigate the nature of the fuel/cladding interface for this fuel type after irradiation, fuel plates were fabricated using a friction bonding process, tested in INL's advanced test reactor (ATR), and then subsequently characterized using optical metallography, scanning electron microscopy, and transmission electron microscopy. Results of this characterization showed that the fuel/cladding interaction layers present at the U-Mo fuel/AA6061 cladding interface after fabrication became amorphous during irradiation. Up to two main interaction layers, based on composition, could be found at the fuel/cladding interface, depending on location. After irradiation, an Al-rich layer contained very few fission gas bubbles, but did exhibit Xe enrichment near the AA6061 cladding interface. Another layer, which contained more Si, had more observable fission gas bubbles. In the samples produced using a focused ion beam at the interaction zone/AA6061 cladding interface, possible indications of porosity/debonding were found, which suggested that the interface in this location is relatively weak.

Dry Sliding Wear Charactristics of Aluminum 6061-T6, Magnesium AZ31 and Rock Dust Composite

NASA Astrophysics Data System (ADS)

Balachandar, R.; Balasundaram, R.; Rajkumar, G.

2018-02-01

In recent years, the use of aluminum composite is gaining popularity in a wide range of applications like automobiles, aerospace and constructions (both interior & exterior) panels etc., due to its high strength, low density characteristics. Various reinforcing materials are used with aluminum 6061-T6 in order to have better mechanical properties. The addition of 0.3% of magnesium AZ31 will increase the ultimate tensile strength by 25 %. The reinforcement of rock dust will decrease the density. Hence, in order to have an advantages of magnesium AZ31 and rock dust, in this work, these two constitutes are varied from 1% to 2% on the base material of Al6061-T6 in stir casting. To evaluate the wear characteristics, Pin on disc is used in these composites. The input parameters are speed, time & load. The output response is wear. To minimize the number of experiments, L9 orthogonal array is used. The test results showed that a composite of 97% of Al (6061-T6), 1% Mg (AZ31) & 2 % of rock dust produced less wear. To find the best value of operating parameter for each sample, ANN-GA is used.

Galvanic coupling between D6AC steel, 6061-T6 aluminum, Inconel 718 and graphite-epoxy composite material: Corrosion occurrence and prevention

NASA Technical Reports Server (NTRS)

Danford, M. D.; Higgins, R. H.

1983-01-01

The effects of galvanic coupling between D6AC steel, 6061-T6 aluminum, Inconel 718, and graphite-epoxy composite material (G/E) in 3.5% NaCl were studied. Measurements of corrosion potentials, galvanic currents and corrosion rates of the bare metals using weight-loss methods served to establish the need for corrosion protection in cases where D6AC steel and 6061-T6 aluminum are galvanically coupled to G/E in salt water while Inconel 718 was shown to be compatible with G/E. Six tests were made to study corrosion protective methods for eliminating galvanic corrosion in the cases of D6AC steel and 6061-T6 aluminum coupled to G/E. These results indicate that, when the G/E is completely coated with paint or a paint/polyurethane resin combination, satisfactory protection of the D6AC steel is achieved with either a coat of zinc-rich primer or a primer/topcoat combination. Likewise, satisfactory corrosion protection of the aluminum is achieved by coating it with an epoxy coating system.

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.

Advanced Cast Aluminum Alloys

DTIC Science & Technology

2009-02-01

This production route has demonstrated that aluminum alloys with yield strengths in excess of 690 MPa with good elongation (reportedly 8%) are...series of aluminum alloys have poor-to-fair general corrosion resistance and poor-to-good stress corrosion cracking resistance. Wrought 2519...aluminum alloy has good strength, good ballistic performance, good stress corrosion cracking resistance but only fair general corrosion resistance

SLM processing-microstructure-mechanical property correlation in an aluminum alloy produced by additive manufacturing

NASA Astrophysics Data System (ADS)

Alejos, Martin Fernando

Additive manufacturing has become a highly researched topic in recent years all over the world. The current research evaluates the merits of additive manufacturing based on the mechanical, microstructural, and fracture properties of additive manufactured AlSi10Mg test specimens. The additive manufactured build plates consisted of tensile and fatigue test specimens. They were printed in the 0°, 30°, 60°, and 90° orientations relative to the build platform. Tensile and dynamic fatigue tests were conducted followed by microstructural characterization and fracture analysis. A wrought 6061 T6 aluminum alloy was also tested for comparison. Tensile tests revealed similar ultimate tensile strengths for all aluminum tensile specimens (350-380 MPa). Fatigue strength was greatest for wrought 6061 T6 aluminum (175 MPa). The fatigue behavior was a strong function of build orientation for the additive manufactured specimens. The 0°, 30°, and 60° orientations had fatigue strengths close to 104 MPa while the 90° orientation had a fatigue strength of 125 MPa. All test specimens failed primarily in a ductile manner. The effect of laser power, hatch spacing, and scan speed were also studied using microstructural analysis. Increasing laser power decreased grain size and void size. Increasing scan speed led to the formation of columnar grains. Increasing hatch spacing decreased grain size and the amount of voids present in the microstructure.

Building A Simulation Model For The Prediction Of Temperature Distribution In Pulsed Laser Spot Welding Of Dissimilar Low Carbon Steel 1020 To Aluminum Alloy 6061

NASA Astrophysics Data System (ADS)

Yousef, Adel K. M.; Taha, Ziad. A.; Shehab, Abeer A.

2011-01-01

This paper describes the development of a computer model used to analyze the heat flow during pulsed Nd: YAG laser spot welding of dissimilar metal; low carbon steel (1020) to aluminum alloy (6061). The model is built using ANSYS FLUENT 3.6 software where almost all the environments simulated to be similar to the experimental environments. A simulation analysis was implemented based on conduction heat transfer out of the key hole where no melting occurs. The effect of laser power and pulse duration was studied. Three peak powers 1, 1.66 and 2.5 kW were varied during pulsed laser spot welding (keeping the energy constant), also the effect of two pulse durations 4 and 8 ms (with constant peak power), on the transient temperature distribution and weld pool dimension were predicated using the present simulation. It was found that the present simulation model can give an indication for choosing the suitable laser parameters (i.e. pulse durations, peak power and interaction time required) during pulsed laser spot welding of dissimilar metals.

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)

Heat Treatment of Gas-Atomized Powders for Cold Spray Deposition

NASA Astrophysics Data System (ADS)

Story, William A.; Brewer, Luke N.

2018-02-01

This communication demonstrates the efficacy of heat treatment on the improved deposition characteristics of aluminum alloy powders. A novel furnace was constructed for solutionizing of feedstock powders in an inert atmosphere while avoiding sintering. This furnace design achieved sufficiently high cooling rates to limit re-precipitation during powder cooling. Microscopy showed homogenization of the powder particle microstructures after heat treatment. Cold spray deposition efficiency with heat-treated powders substantially increased for the alloys AA2024, AA6061, and AA7075.

The FEM simulation of continuous rotary extrusion (CRE) of aluminum alloy AA3003

NASA Astrophysics Data System (ADS)

Rajendran, Nijenthan; Valberg, Henry; Misiolek, Wojciech Z.

2017-10-01

Continuous Rotary Extrusion (CRE) process is also known in literature under Conform TM name and it is mainly used for the continuous extrusion of Aluminum and Copper alloys. CRE use a feedstock in the form of rod, powders and chips, which are fed into the groove of the rotating wheel. As the wheel rotates the feedstock moves along with it due to friction with the wheel. Once the feedstock reaches the abutment the material deforms plastically and it is extruded through the die. CRE has lot to offer when compared to other more conventional extrusion processes such as low energy input, no limit in billet length as it is a continuous process as well as improved material physical properties due to plastic deformation under constant parameters. In this work a FEM model has been developed using Deform TM 3D, to study the metal flow and state variables of AA3003 CRE extrusion. The effect of extrusion wheel velocity has been investigated. The results show that increase in wheel velocity will heat up the feedstock metal due to high shear deformation and higher friction, which significantly changes metal flow conditions at the die exit.

Evaluation of Surface Roughness by Image Processing of a Shot-Peened, TIG-Welded Aluminum 6061-T6 Alloy: An Experimental Case Study

PubMed Central

Rawashdeh, Nathir A.

2018-01-01

Visual inspection through image processing of welding and shot-peened surfaces is necessary to overcome equipment limitations, avoid measurement errors, and accelerate processing to gain certain surface properties such as surface roughness. Therefore, it is important to design an algorithm to quantify surface properties, which enables us to overcome the aforementioned limitations. In this study, a proposed systematic algorithm is utilized to generate and compare the surface roughness of Tungsten Inert Gas (TIG) welded aluminum 6061-T6 alloy treated by two levels of shot-peening, high-intensity and low-intensity. This project is industrial in nature, and the proposed solution was originally requested by local industry to overcome equipment capabilities and limitations. In particular, surface roughness measurements are usually only possible on flat surfaces but not on other areas treated by shot-peening after welding, as in the heat-affected zone and weld beads. Therefore, those critical areas are outside of the measurement limitations. Using the proposed technique, the surface roughness measurements were possible to obtain for weld beads, high-intensity and low-intensity shot-peened surfaces. In addition, a 3D surface topography was generated and dimple size distributions were calculated for the three tested scenarios: control sample (TIG-welded only), high-intensity shot-peened, and low-intensity shot-peened TIG-welded Al6065-T6 samples. Finally, cross-sectional hardness profiles were measured for the three scenarios; in all scenarios, lower hardness measurements were obtained compared to the base metal alloy in the heat-affected zone and in the weld beads even after shot-peening treatments. PMID:29748520

Evaluation of Surface Roughness by Image Processing of a Shot-Peened, TIG-Welded Aluminum 6061-T6 Alloy: An Experimental Case Study.

PubMed

Atieh, Anas M; Rawashdeh, Nathir A; AlHazaa, Abdulaziz N

2018-05-10

Visual inspection through image processing of welding and shot-peened surfaces is necessary to overcome equipment limitations, avoid measurement errors, and accelerate processing to gain certain surface properties such as surface roughness. Therefore, it is important to design an algorithm to quantify surface properties, which enables us to overcome the aforementioned limitations. In this study, a proposed systematic algorithm is utilized to generate and compare the surface roughness of Tungsten Inert Gas (TIG) welded aluminum 6061-T6 alloy treated by two levels of shot-peening, high-intensity and low-intensity. This project is industrial in nature, and the proposed solution was originally requested by local industry to overcome equipment capabilities and limitations. In particular, surface roughness measurements are usually only possible on flat surfaces but not on other areas treated by shot-peening after welding, as in the heat-affected zone and weld beads. Therefore, those critical areas are outside of the measurement limitations. Using the proposed technique, the surface roughness measurements were possible to obtain for weld beads, high-intensity and low-intensity shot-peened surfaces. In addition, a 3D surface topography was generated and dimple size distributions were calculated for the three tested scenarios: control sample (TIG-welded only), high-intensity shot-peened, and low-intensity shot-peened TIG-welded Al6065-T6 samples. Finally, cross-sectional hardness profiles were measured for the three scenarios; in all scenarios, lower hardness measurements were obtained compared to the base metal alloy in the heat-affected zone and in the weld beads even after shot-peening treatments.

Design and Analysis of Wind Turbine Blade Hub using Aluminium Alloy AA 6061-T6

NASA Astrophysics Data System (ADS)

Ravikumar, S.; Jaswanthvenkatram, V.; Sai kumar, Y. J. N. V.; Sohaib, S. Md.

2017-05-01

This work presents the design and analysis of horizontal axis wind turbine blade hub using different material. The hub is very crucial part of the wind turbine, which experience the loads from the blades and the loads were transmitted to the main shaft. At present wind turbine is more expensive and weights more than a million pounds, with the nacelle, rotor hub and blades accounting for most of the weight. In this work Spheroidal graphite cast iron GGG 40.3 is replaced by aluminium alloy 6061-T6 to enhance the casting properties and also to improve the strength-weight ratio. This transition of material leads to reduction in weight of the wind turbine. All the loads caused by wind and extreme loads on the blades are transferred to the hub. Considering the IEC 61400-1 standard for defining extreme loads on the hub the stress and deflection were calculated on the hub by using Finite element Analysis. Result obtained from ANSYS is compared and discussed with the existing design.

Non-destructive identification of unknown minor phases in polycrystalline bulk alloys using three-dimensional X-ray diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yiming, E-mail: yangyiming1988@outlook.com

Minor phases make considerable contributions to the mechanical and physical properties of metals and alloys. Unfortunately, it is difficult to identify unknown minor phases in a bulk polycrystalline material using conventional metallographic methods. Here, a non-destructive method based on three-dimensional X-ray diffraction (3DXRD) is developed to solve this problem. Simulation results demonstrate that this method is simultaneously able to identify minor phase grains and reveal their positions, orientations and sizes within bulk alloys. According to systematic simulations, the 3DXRD method is practicable for an extensive sample set, including polycrystalline alloys with hexagonal, orthorhombic and cubic minor phases. Experiments were alsomore » conducted to confirm the simulation results. The results for a bulk sample of aluminum alloy AA6061 show that the crystal grains of an unexpected γ-Fe (austenite) phase can be identified, three-dimensionally and nondestructively. Therefore, we conclude that the 3DXRD method is a powerful tool for the identification of unknown minor phases in bulk alloys belonging to a variety of crystal systems. This method also has the potential to be used for in situ observations of the effects of minor phases on the crystallographic behaviors of alloys. - Highlights: •A method based on 3DXRD is developed for identification of unknown minor phase. •Grain position, orientation and size, is simultaneously acquired. •A systematic simulation demonstrated the applicability of the proposed method. •Experimental results on a AA6061 sample confirmed the practicability of the method.« less

Dissolution and Separation of Aluminum and Aluminosilicates

DOE PAGES

McFarlane, Joanna; Benker, Dennis; DePaoli, David W.; ...

2015-12-19

The selection of an aluminum alloy for target irradiation affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the dissolver, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. Aluminosilicate dissolution presents challenges in a number of different areas, metals extraction from minerals, flyash treatment, and separations from aluminum alloys. We present experimental work that attempts to maximize dissolution of aluminum metal, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as amore » function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. Our data have been compared with published calculations of aluminum phase diagrams. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.« less

Through-thickness recrystallization characteristics of a laminated AA3xxx–AA6xxx aluminum alloy system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liao, L.H., E-mail: l2liao@uwaterloo.ca; Jin, H.; Gallerneault, M.

2015-03-15

The through-thickness annealing behavior of a laminated AA3xxx–AA6xxx alloy system at 300 °C has been studied by scanning electron microscopy, electron backscatter diffraction analysis, electron probe micro-analysis, differential scanning calorimetry, and hardness measurement. Results show that the recrystallization process starts at the interface region between the AA3xxx (clad) and AA6xxx (core) layers. Subsequently, the recrystallization process front progresses into the core layer, while the clad layer is the last region to recrystallize. It is also found that precipitation precedes recrystallization in the entire laminate at the investigated temperature. The preferential onset of recrystallization at the interface region is attributed tomore » the net driving pressure being the highest in this region. The factors that lead to such enhanced net driving pressure are (a) deformation incompatibility between the two alloy layers, (b) lower solute content of the interface, which also leads to lower volume fraction of precipitates, and (c) an accelerated rate of precipitate coarsening due to the presence of a higher density of dislocations. The gradual progress of recrystallization from the interface towards the core layer is dictated by precipitate coarsening and the dependence of its rate on the density of deformation-induced dislocations. The lower driving pressure due to lower work hardening capacity, high solute drag pressure due to Mn, and additional Zener drag from precipitates that form due to solute redistribution during annealing explain the late initiation of recrystallization in the clad layer. - Highlights: • The through-thickness recrystallization of a laminated system is investigated. • The early onset of recrystallization at the interface is discussed. • The effects of precipitation and coarsening on recrystallization are analyzed.« less

Investigation of rapidly solidified aluminum by using diamond turning and a magnetorheological finishing process

NASA Astrophysics Data System (ADS)

Cheng, Yuan-Chieh; Hsu, Wei-Yao; Kuo, Ching-Hsiang; Abou-El-Hossein, Khaled; Otieno, Timothy

2015-08-01

The metal mirror has been widely used in optical application for a longtime. Especially the aluminum 6061 is often considered the preferred material for manufacturing optical components for ground-based astronomical applications. One reason for using this material is its high specific stiffness and excellent thermal properties. However, a large amount of data exists for this material and commercially available aluminum 6061 using single point diamond turning (SPDT) and polishing process can achieve surface roughness values of approximately 2 to 4 nm, which is adequate for applications that involve the infrared spectral range, but not for the shorter spectral range. A novel aluminum material, fabricated using a rapid solidification process that is equivalent to the conventional aluminum 6061 alloy grade has been used in optical applications in recent years because of its smaller grain size. In this study, the surface quality of the rapid solidification aluminum after single point diamond turning and followed by magnetorheological finish (MRF) process is investigated and compared with conventional aluminum 6061. Both the surface roughness Ra was evaluated using white light interferometers. Finally, indicators such as optimal fabrication parameter combination and optical performance are discussed.

Influence of surface pretreatments on the quality of trivalent chromium process coatings on aluminum alloy

NASA Astrophysics Data System (ADS)

Viroulaud, Rémi; Światowska, Jolanta; Seyeux, Antoine; Zanna, Sandrine; Tardelli, Joffrey; Marcus, Philippe

2017-11-01

The effects of surface pretreatments (degreasing and pickling) on the characteristics of the Trivalent Chromium Process (TCP) coating on pure aluminum and on AA2024-T351 aluminum alloy were investigated here by means of surface sensitive techniques: X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The XPS and ToF-SIMS results evidence that the TCP coating homogeneity is strongly dependent on the pretreatment process used. The TCP coverage factor, calculated from XPS results, is significantly lower, on both pure aluminum and AA2024-T351 alloy surface, when a pickling step is applied. One of the main effects of pickling pretreatment is strong metallic copper enrichment at the surface of the 2024 alloy, associated with chemical dissolution of Al-Cu intermetallic particles. However, it is evidenced here, that the copper enrichment is not detrimental for the quality of the TCP coating. The coating failure, observed when the pickling step is applied, can be assigned to a faster kinetics of the coating growth leading to formation of thicker conversion coating more susceptible to cracking or to the localized presence of aluminum fluoride species leading to the appearance of coating defects or detachment.

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

Effect of the Microstructure on Diffusion Bonded AA5083, AA6082 and AA7075 Aluminium Alloys

NASA Astrophysics Data System (ADS)

Venugopal, S.; Mahendran, G.

2018-05-01

Rolled plates of aluminium alloys AA5083, AA6082 and AA7075 of 5 mm thickness are joined by diffusion bonding at varied parameters. The microstructure evolution of AA5083, AA6082 and AA7075 aluminium alloys is characterized by Transmission Electron Microscopy (TEM). Metallurgical investigations and mechanical tests are also performed to correlate the results of the TEM investigations with the mechanical properties of the produced diffusion bonded joints. It is observed that the bonding and shear strength of the alloys increase with the increase in bonding temperature, due to the diffusion of micro-constituents in the interface. High temperature enhances the uniform distribution of secondary phase particles and reduces pore formation/defects in the bonded joints.

Dynamic Behavior of AA2519-T8 Aluminum Alloy Under High Strain Rate Loading in Compression

NASA Astrophysics Data System (ADS)

Olasumboye, A. T.; Owolabi, G. M.; Odeshi, A. G.; Yilmaz, N.; Zeytinci, A.

2018-06-01

In this study, the effects of strain rate on the dynamic behavior, microstructure evolution and hence, failure of the AA2519-T8 aluminum alloy were investigated under compression at strain rates ranging from 1000 to 3500 s-1. Cylindrical specimens of dimensions 3.3 mm × 3.3 mm (L/D = 1) were tested using the split-Hopkinson pressure bar integrated with a digital image correlation system. The microstructure of the alloy was assessed using optical and scanning electron microscopes. Results showed that the dynamic yield strength of the alloy is strain rate dependent, with the maximum yield strength attained by the material being 500 MPa. The peak flow stress of 562 MPa was attained by the material at 3500 s-1. The alloy also showed a significant rate of strain hardening that is typical of other Al-Cu alloys; the rate of strain hardening, however, decreased with increase in strain rate. It was determined that the strain rate sensitivity coefficient of the alloy within the range of high strain rates used in this study is approximately 0.05 at 0.12 plastic strain; a more significant value than what was reported in literature under quasi-static loading. Micrographs obtained showed potential sites for the evolution of adiabatic shear band at 3500 s-1, with a characteristic circular-shaped surface profile comprising partially dissolved second phase particles in the continuous phase across the incident plane of the deformed specimen. The regions surrounding the site showed little or no change in the size of particles. However, the constituent coarse particles were observed as agglomerations of fractured pieces, thus having a shape factor different from those contained in the as-received alloy. Since the investigated alloy is a choice material for military application where it can be exposed to massive deformation at high strain rates, this study provides information on its microstructural and mechanical responses to such extreme loading condition.

Dynamic Behavior of AA2519-T8 Aluminum Alloy Under High Strain Rate Loading in Compression

NASA Astrophysics Data System (ADS)

Olasumboye, A. T.; Owolabi, G. M.; Odeshi, A. G.; Yilmaz, N.; Zeytinci, A.

2018-02-01

In this study, the effects of strain rate on the dynamic behavior, microstructure evolution and hence, failure of the AA2519-T8 aluminum alloy were investigated under compression at strain rates ranging from 1000 to 3500 s-1. Cylindrical specimens of dimensions 3.3 mm × 3.3 mm (L/D = 1) were tested using the split-Hopkinson pressure bar integrated with a digital image correlation system. The microstructure of the alloy was assessed using optical and scanning electron microscopes. Results showed that the dynamic yield strength of the alloy is strain rate dependent, with the maximum yield strength attained by the material being 500 MPa. The peak flow stress of 562 MPa was attained by the material at 3500 s-1. The alloy also showed a significant rate of strain hardening that is typical of other Al-Cu alloys; the rate of strain hardening, however, decreased with increase in strain rate. It was determined that the strain rate sensitivity coefficient of the alloy within the range of high strain rates used in this study is approximately 0.05 at 0.12 plastic strain; a more significant value than what was reported in literature under quasi-static loading. Micrographs obtained showed potential sites for the evolution of adiabatic shear band at 3500 s-1, with a characteristic circular-shaped surface profile comprising partially dissolved second phase particles in the continuous phase across the incident plane of the deformed specimen. The regions surrounding the site showed little or no change in the size of particles. However, the constituent coarse particles were observed as agglomerations of fractured pieces, thus having a shape factor different from those contained in the as-received alloy. Since the investigated alloy is a choice material for military application where it can be exposed to massive deformation at high strain rates, this study provides information on its microstructural and mechanical responses to such extreme loading condition.

Treatments To Produce Stabilized Aluminum Mirrors for Cryogenic Uses

NASA Technical Reports Server (NTRS)

Zewari, Wahid; Barthelmy, Michael; Ohl, Raymond

2005-01-01

Five metallurgical treatments have been tested as means of stabilizing mirrors that are made of aluminum alloy 6061 and are intended for use in cryogenic applications. Aluminum alloy 6061 is favored as a mirror material by many scientists and engineers. Like other alloys, it shrinks upon cool-down from room temperature to cryogenic temperature. This shrinkage degrades the optical quality of the mirror surfaces. Hence, the metallurgical treatments were tested to determine which one could be most effective in minimizing the adverse optical effects of cooldown to cryogenic temperatures. Each of the five metallurgical treatments comprises a multistep process, the steps of which are interspersed with the steps of the mirror-fabrication process. The five metallurgical-treatment/fabrication.- process combinations were compared with each other and with a benchmark fabrication process, in which a mirror is made from an alloy blank by (1) symmetrical rough machining, (2) finish machining to within 0.006 in. (. 0.15 mm) of final dimensions, and finally (3) diamond turning to a mirror finish.

Improvements to the strength and corrosion resistance of aluminum-magnesium-manganese alloys of near-AA5083 chemistry

NASA Astrophysics Data System (ADS)

Carroll, Mark Christopher

Aluminum alloys of the 5000 series (AI-Mg-Mn) are extremely popular in a wide range of applications that call for a balance of moderately high strength, good corrosion resistance, and light weight, all at a moderate cost. One of the most popular 5000 series alloys is designated A1-5083, containing, in addition to aluminum, approximately 4 wt% magnesium and 0.7 wt% manganese. In order to increase the range of versatility of this particular alloy, a number of modifications have been examined that will potentially improve the strength and corrosion resistance characteristics while maintaining a chemical composition that is very close to the proven 5083 alloy. The strength of the 5083-based alloys under study are investigated with two goals in mind---to maximize the potential strength characteristics in a "standard" 5083 form through changes in minor processing parameters or through minor alloying additions. Increasing the standard alloy's potential is possible through improved efficiency of "preprocessing" heat treatments that maximize the homogeneous dispersion of secondary manganese-based particles. For the modified alloy study, additions of scandium and zirconium are shown to improve strength not only by forming secondary particles in the alloy, but also through substitutional solid solution strengthening, even when added at very small levels. Corrosion resistance of these 5083-based alloys is investigated once again through minor alloying additions; specifically zinc, copper, and silver. Zinc is particularly effective in that it changes the corrosion-susceptible binary aluminum-magnesium phase that would otherwise form on grain boundaries following exposure to moderately elevated temperatures for extended periods of time to a ternary aluminum-magnesium-zinc phase. This chemical composition of this ternary phase that forms following zinc additions can be further altered through minor additions of copper and silver. By determining threshold levels for these

Effect of Localized Corrosion on Fatigue-Crack Growth in 2524-T3 and 2198-T851 Aluminum Alloys Used as Aircraft Materials

NASA Astrophysics Data System (ADS)

Moreto, J. A.; Broday, E. E.; Rossino, L. S.; Fernandes, J. C. S.; Bose Filho, W. W.

2018-03-01

Corrosion and fatigue of aluminum alloys are major issues for the in-service life assessment of aircraft structures and for the management of aging air fleets. The aim of this work was to evaluate the effect of localized corrosion on fatigue crack growth (FCG) resistance of the AA2198-T851 Al-Li alloy (Solution Heat Treated, Cold Worked, and Artificially Aged), comparing it with the FCG resistance of AA2524-T3 (Solution Heat Treated and Cold Worked), considering the effect of seawater fog environment. Before fatigue tests, the corrosion behavior of 2198-T851 and 2524-T3 aluminum alloys was verified using open circuit potential and potentiodynamic polarization techniques. Fatigue in air and corrosion fatigue tests were performed applying a stress ratio (R) of 0.1, 15 Hz (air) and 0.1 Hz (seawater fog) frequencies, using a sinusoidal waveform in all cases. The results showed that the localized characteristics of the 2198-T851 and 2524-T3 aluminum alloys are essentially related to the existence of intermetallic compounds, which, due to their different nature, may be cathodic or anodic in relation to the aluminum matrix. The corrosive medium has affected the FCG rate of both aluminum alloys, in a quite similar way.

Damage percolation during stretch flange forming of aluminum alloy sheet

NASA Astrophysics Data System (ADS)

Chen, Zengtao; Worswick, Michael J.; Keith Pilkey, A.; Lloyd, David J.

2005-12-01

A multi-scale finite element (FE)-damage percolation model was employed to simulate stretch flange forming of aluminum alloys AA5182 and AA5754. Material softening and strain gradients were captured using a Gurson-based FE model. FE results were then fed into the so-called damage percolation code, from which the damage development was modelled within measured microstructures. The formability of the stretch flange samples was predicted based upon the onset of catastrophic failure triggered by profuse void coalescence within the measured second-phase particle field. Damage development is quantified in terms of crack and void areal fractions, and compared to metallographic results obtained from interrupted stretch flange specimens. Parametric study is conducted on the effect of void nucleation strain in the prediction of formability of stretch flanges to "calibrate" proper nucleation strains for both alloys.

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)

Double-pulse femtosecond laser peening of aluminum alloy AA5038: Effect of inter-pulse delay on transient optical plume emission and final surface micro-hardness

NASA Astrophysics Data System (ADS)

Ageev, E. I.; Bychenkov, V. Yu.; Ionin, A. A.; Kudryashov, S. I.; Petrov, A. A.; Samokhvalov, A. A.; Veiko, V. P.

2016-11-01

Double-pulse ablative femtosecond laser peening of the AA5038 aluminum alloy surface in the phase explosion regime results in its enhanced microhardness, which monotonously decreases till the initial value versus inter-pulse delay, increasing on a sub-nanosecond timescale. Optical emission spectroscopy of the double-pulse ablative plume reveals the same trend in the yield of the corresponding atomic and ion emission versus inter-pulse delay, enlightening the interaction of the second femtosecond laser pump pulse with the surface and the resulting plume.

Light weight and high strength materials made of recycled steel and aluminum

NASA Astrophysics Data System (ADS)

Nounezi, Thomas

Recycling has proven not only to address today's economical, environmental and social issues, but also to be imperative for the sustainability of human technology. The current thesis has investigated the feasibility of a new philosophy for Recycling (Alloying-Recycling) using steel 1020 and aluminum 6061T6. The study was limited to the metallurgical aspects only and has highlighted the potential of recycled alloys made of recycled aluminum and steel to exhibit substantially increased wear resistance and strength-to-weight ratio as compared to initial primary materials. Three alloy-mixtures are considered: TN3 (5wt% 1020 +95wt% 6061T6); TN5 (0.7wt% 1020 + 99.3wt% 6061T6); and TN4 (10wt% 6061T6 + 90wt% 1020). A Tucker induction power supply system (3kW; 135-400 kHz) is used to melt the alloy mixtures for casting in graphite crucibles. Heat treatment of the cast samples is done using a radiation box furnace. Microscopy, Vickers hardness and pin-on-disc abrasive wear tests are performed. Casting destroyed the initial microstructures of the alloys leading to a hardness reduction in the as-cast and solution heat-treated aluminum rich samples to 60 Hv from 140 Hv. Ageing slightly increased the hardness of the cast samples and provided a wear resistance two times higher than that of the initial 6061T6 material. On the steel rich side, the hardness of the as-cast TN4 was 480 Hv, which is more than twice as high as the initial hardness of steel 1020 of 202 Hv; this hints to strong internal and residual stress, probably martensite formation during fast cooling following casting. Solution heat treatment lowered the hardness to the original value of steel 1020, but provided about ten (10) times higher wear resistance; this suggests higher ductility and toughness of normalised TN4 as compared to 1020. In addition, TN4 exhibits about 25% weight reduction as compared to 1020. The actual recycling process and the effect of non-metallic impurities shall be investigated in future

The effect of precipitation on the evolution of recrystallization textures in an AA 8011 aluminum alloy sheet

NASA Astrophysics Data System (ADS)

Ryu, Jong-Ho; Lee, Yoon-Soo; Lee, Dong Nyung

2001-06-01

The texture of an AA 8011 aluminum alloy sheet cold rolled by 95% showed a typical β-fiber, which runs from the copper orientation [C={112}<111>] over S [{123}<634>] to brass [B={011}<112>]. The development of annealing textures depended on annealing temperatures due to the interaction between precipitation and recrystallization. Upon annealing at a low temperature of 275°C, precipitation took place before recrystallization. This led to a weak recrystallization texture consisting of {011}<122>, {001˜<100>, and {hk0}<001>, among which the {011}<122> orientation developed near large FeAl3 particles as the main orientation and the cube [{001}<100>] orientation originating from the matrix was relatively weak. After annealing at 350 and 500°C, a strong cube texture developed along with a weak {011}<122> orientation. When the cube orientation developed, the copper orientation disappeared most rapidly. These results were discussed based on the interaction between precipitation and recrystallization.

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.

Experimental Investigation on Friction Stir Welding of Cryorolled AA2219 Aluminum Alloy Joints

NASA Astrophysics Data System (ADS)

Babu, K. Kamal; Panneerselvam, K.; Sathiya, P.; Haq, A. Noorul; Sundarrajan, S.; Mastanaiah, P.; Murthy, C. V. Srinivasa

2017-07-01

In this paper, experimental investigation on cryorolled aluminum AA2219-T87 plate by using friction stir welding (FSW) process is carried out. AA2219-T87 plates with a size of 200×100×22.4 mm were rolled and reduced to 12.2mm thickness (more than 45% of reduction in total thickness of the base material) at cryogenic temperature (operating temperature range -90--30∘C). The cryorolled (CR) plates have reduced grain size, improved hardness and increased corrosion resistance property compared with the uncryorolled AA2219-T87 plates. FSW joints of cryorolled AA2219-T87 plates were prepared using cylindrical threaded FSW tool pin profile. Mechanical and metallurgical behaviors of friction stir welded joints were analyzed and the effects of the FSW process parameters are discussed in this paper. The variation of microhardness in the FSW joint regions were correlated with the microstructure of FSW joints. Cryorolled plate and FSW joints were tested for corrosion resistance using potentiodynamic polarization test. FSW joints shows better result during the corrosion resistance analysis compared to base AA2219-T87. The X-ray diffraction (XRD) test results showed that fine α-Al grains with eutectic phase (Al2Cu) were present in the weld nugget (WN). The large clusters of strengthening precipitates were reduced in size and merged with the weld nugget portion.

The effect of oxide film properties on the corrosion behavior of SiC/Al metal-matrix composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Golledge, S.L.

1991-01-01

Oxide growth on pure aluminum, aluminum alloy 6061, and the aluminum-based metal matrix composite SiC/AA6061 was studied, and the properties of the oxides related to the pit-initiation behavior of the materials. The objectives of the work were to identify the effect of alloying elements and SiC reinforcement on the oxide film, and to better understand how the oxide properties control pit initiation behavior. To this end, electrochemical and optical studies of the materials were carried out in a buffered sodium/boric acid solution at pH values of 8.4 and 7.2. The alloy and metal-matrix composite showed a slightly lesser tendency tomore » pit than pure aluminum, as measured by the pitting potential. The oxide on the composite was less resistant to pit initiation, and was found to exhibit slower repassivation rates than the other materials. The repassivation behavior and resistance to pit initiation were quite similar in the case of the alloy and the pure aluminum. Induction times for pit initiation were consistent with the predictions of Heusler's model for the breakdown of passivity.« less

The Role of Second Phase Hard Particles on Hole Stretchability of two AA6xxx Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Xiaohua; Sun, Xin; Golovashchenko, Sergey F.

The hole stretchability of two Aluminum Alloys (AA6111 and AA6022) are studied by using a two stages integrated finite element framework where the edge geometry and edge damages from the hole piercing processes were considered in the subsequent hole expansion processes. Experimentally it has been found that AA6022 has higher hole expansion ratios than those of AA6111. This observation has been nicely captured by finite element simulations. The main cause of differences have been identified to the volume fractions of the random distributed second phase hard particles which play a critical role in determining the fracture strains of the materials.

Casting Characteristics of High Cerium Content Aluminum Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weiss, D; Rios, O R; Sims, Z C

This paper compares the castability of the near eutectic aluminum-cerium alloy system to the aluminum-silicon and aluminum-copper systems. The alloys are compared based on die filling capability, feeding characteristics and tendency to hot tear in both sand cast and permanent mold applications. The castability ranking of the binary Al–Ce systems is as good as the aluminum-silicon system with some deterioration as additional alloying elements are added. In alloy systems that use cerium in combination with common aluminum alloying elements such as silicon, magnesium and/or copper, the casting characteristics are generally better than the aluminum-copper system. In general, production systems formore » melting, de-gassing and other processing of aluminum-silicon or aluminum-copper alloys can be used without modification for conventional casting of aluminum-cerium alloys.« less

Aluminum Target Dissolution in Support of the Pu-238 Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

McFarlane, Joanna; Benker, Dennis; DePaoli, David W

2014-09-01

Selection of an aluminum alloy for target cladding affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the caustic dissolution step, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. We present a study to maximize dissolution of aluminum metal alloy, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as a function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. These datamore » have been compared with published calculations of aluminum phase diagrams. Temperature logging during the transients has been investigated as a means to generate kinetic and mass transport data on the dissolution process. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.« less

Galvanic Corrosion In (Graphite/Epoxy)/Alloy Couples

NASA Technical Reports Server (NTRS)

Danford, Merlin D.; Higgins, Ralph H.

1988-01-01

Effects of galvanic coupling between graphite/epoxy composite material, G/E, and D6AC steel, 6061-T6 aluminum, and Inconel(R) 718 nickel alloy in salt water described in report. Introductory section summarizes previous corrosion studies of G/E with other alloys. Details of sample preparation presented along with photographs of samples before and after immersion.

Fatigue Crack-Growth Resistance of Aluminum Alloys Under Spectrum Loading. Volume 2. Aluminum Lithium Alloys.

DTIC Science & Technology

1985-12-01

Effects on Fatigue Crack Propagation in 2024 -T3 Aluminum Alloy ," Eng. Frac. Mech, * Vol. 8, 1976, p. 657...Retardation Behavior of 7075 * and 2024 Aluminum Alloys ," ASTNI STP 631, 1977. 89 hill". .A•, - . 34. Chanani, G.R., "Investigation of Effects of Saltwater...1.0 9,අ &M Ma ki-L6 &Ŗ &- La 06 lin "Ll Ull 1.25 "A Lm Wit Rtlc()FIV WtklLl’-"- ll*A FATIGUE CRACK-GROWTH RESISTANCE OF ALUMINUM ALLOYS

Multiphase aluminum equations of state via density functional theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sjostrom, Travis; Crockett, Scott; Rudin, Sven

2016-10-03

We have performed density functional theory (DFT) based calculations for aluminum in extreme conditions of both pressure and temperature, up to five times compressed ambient density, and over 1 000 000 K in temperature. In order to cover such a domain, DFT methods including phonon calculations, quantum molecular dynamics, and orbital-free DFT are employed. Our results are then used to construct a SESAME equation of state for the aluminum 1100 alloy, encompassing the fcc, hcp, and bcc solid phases as well as the liquid regime. We also provide extensive comparison with experiment, and based on this we also provide amore » slightly modified equation of state for the aluminum 6061 alloy.« less

The fracture of boron fibre-reinforced 6061 aluminium alloy

NASA Technical Reports Server (NTRS)

Wright, M. A.; Welch, D.; Jollay, J.

1979-01-01

The fracture of 6061 aluminium alloy reinforced with unidirectional and cross-plied 0/90 deg, 0/90/+ or - 45 deg boron fibres has been investigated. The results have been described in terms of a critical stress intensity, K(Q). Critical stress intensity factors were obtained by substituting the failure stress and the initial crack length into the appropriate expression for K(Q). Values were obtained that depended on the dimensions of the specimens. It was therefore concluded that, for the size of specimen tested, the values of K(Q) did not reflect any basic materials property.

The influence of process parameters on porosity formation in hybrid LASER-GMA welding of AA6082 aluminum alloy

NASA Astrophysics Data System (ADS)

Ascari, Alessandro; Fortunato, Alessandro; Orazi, Leonardo; Campana, Giampaolo

2012-07-01

This paper deals with an experimental campaign carried out on AA6082 8 mm thick plates in order to investigate the role of process parameters on porosity formation in hybrid LASER-GMA welding. Bead on plate weldments were obtained on the above mentioned aluminum alloy considering the variation of the following process parameters: GMAW current (120 and 180 A for short-arc mode, 90 and 130 A for pulsed-arc mode), arc transfer mode (short-arc and pulsed-arc) and mutual distance between arc and LASER sources (0, 3 and 6 mm). Porosities occurring in the fused zone were observed by means of X-ray inspection and measured exploiting an image analysis software. In order to understand the possible correlation between process parameters and porosity formation an analysis of variance statistical approach was exploited. The obtained results pointed out that GMAW current is significant on porosity formation, while the distance between the sources do not affect this aspect.

Microstructure Stability During Creep of Friction Stir Welded AA2024-T3 Alloy

NASA Astrophysics Data System (ADS)

Regev, Michael; Rashkovsky, Tal; Cabibbo, Marcello; Spigarelli, Stefano

2018-01-01

The poor weldability of the AA2024 aluminum alloy limits its use in industrial applications. Because friction stir welding (FSW) is a non-fusion welding process, it seems to be a promising solution for welding this alloy. In the current study, FSW was applied to butt weld AA2024-T3 aluminum alloy plates. Creep tests were conducted at 250 and at 315 °C on both the parent material and the friction stir welded specimens. The microstructures of the welded and non-welded AA2024-T3 specimens before and after the creep tests were studied and compared. A comprehensive transmission electron microscopy study together with a high-resolution scanning electron microscopy study and energy-dispersive x-ray spectroscopy analysis was conducted to investigate the microstructure stability. The parent material seems to contain two kinds of Cu-rich precipitates—coarse precipitates of a few microns each and uniformly dispersed fine nanosized precipitates. Unlike the parent material, the crept specimens were found to contain the two kinds of precipitates mentioned above together with platelet-like precipitates. In addition, extensive decoration of the grain boundaries with precipitates was clearly observed in the crept specimens. Controlled aging experiments for up to 280 h at the relevant temperatures were conducted on both the parent material and the welded specimens in order to isolate the contribution of exposure to high temperatures to the microstructure changes. TEM study showed the development of dislocation networks into a cellular dislocation structure in the case of the parent metal. Changes in the dislocation structure as a function of the creep strain and the FSW process were recorded. A detailed creep data analysis was conducted, taking into account the instability of the microstructure.

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.

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.

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.

Effect of Cryorolling and Aging on Fatigue Behavior of Ultrafine-grained Al6061

NASA Astrophysics Data System (ADS)

Yadollahpour, M.; Hosseini-Toudeshky, H.; Karimzadeh, F.

2016-05-01

The effects of cryorolling (rolling at liquid nitrogen temperature) and heat treatment on tensile and high-cycle fatigue properties and fatigue crack growth rate of Al6061 alloy have been investigated in the present work. First, the solid solution-treated bulk Al6061 alloy was subjected to cryorolling with 90% total thickness reduction and subsequent short annealing at 205°C for 5 min and peak aging at 148°C for 39 h to achieve grain refinement and simultaneous improvement of the strength and ductility. Then, hardness measurements, tensile tests, fatigue life, and fatigue crack growth rate tests including fractography analyses using scanning electron microscopy were performed on bulk Al6061 alloy, cryorolled (CR), and cryorolled material followed by peak aging (PA). The PA specimen showed improved yield strength by 24%, ultimate tensile strength by 20%, and ductility by 12% as compared with the bulk Al6061 alloy. It is shown that the fatigue strength of both CR and PA specimens under a high-cycle fatigue regime are larger than that of the bulk Al6061 alloy. Also, fatigue crack growth rates of the CR and PA specimens show significant enhancement in fatigue crack growth resistances as compared with the bulk Al6061 alloy, as a result of grain refinement.

Computational Analysis of Material Flow During Friction Stir Welding of AA5059 Aluminum Alloys

NASA Astrophysics Data System (ADS)

Grujicic, M.; Arakere, G.; Pandurangan, B.; Ochterbeck, J. M.; Yen, C.-F.; Cheeseman, B. A.; Reynolds, A. P.; Sutton, M. A.

2012-09-01

Workpiece material flow and stirring/mixing during the friction stir welding (FSW) process are investigated computationally. Within the numerical model of the FSW process, the FSW tool is treated as a Lagrangian component while the workpiece material is treated as an Eulerian component. The employed coupled Eulerian/Lagrangian computational analysis of the welding process was of a two-way thermo-mechanical character (i.e., frictional-sliding/plastic-work dissipation is taken to act as a heat source in the thermal-energy balance equation) while temperature is allowed to affect mechanical aspects of the model through temperature-dependent material properties. The workpiece material (AA5059, solid-solution strengthened and strain-hardened aluminum alloy) is represented using a modified version of the classical Johnson-Cook model (within which the strain-hardening term is augmented to take into account for the effect of dynamic recrystallization) while the FSW tool material (AISI H13 tool steel) is modeled as an isotropic linear-elastic material. Within the analysis, the effects of some of the FSW key process parameters are investigated (e.g., weld pitch, tool tilt-angle, and the tool pin-size). The results pertaining to the material flow during FSW are compared with their experimental counterparts. It is found that, for the most part, experimentally observed material-flow characteristics are reproduced within the current FSW-process model.

Investigation into the stress corrosion cracking properties of AA2099, an aluminum-lithium-copper alloy

NASA Astrophysics Data System (ADS)

Padgett, Barbara Nicole

Recently developed Al-Li-Cu alloys show great potential for implementation in the aerospace industry because of the attractive mix of good mechanical properties and low density. AA2099 is an Al-Li-Cu alloy with the following composition Al-2.69wt%Cu-1.8wt%Li-0.6wt%Zn-0.3wt%Mg-0.3wt%Mn-0.08wt%Zr. The environmental assisted cracking and localized corrosion behavior of the AA2099 was investigated in this thesis. The consequences of uncontrolled grain boundary precipitation via friction stir welding on the stress corrosion cracking (SCC) behavior of AA2099 was investigated first. Using constant extension rate testing, intergranular corrosion immersion experiments, and potentiodynamic scans, the heat-affected zone on the trailing edge of the weld (HTS) was determined to be most susceptible of the weld zones. The observed SCC behavior for the HTS was linked to the dissolution of an active phase (Al2CuLi, T1) populating the grain boundary. It should be stated that the SCC properties of AA2099 in the as-received condition were determined to be good. Focus was then given to the electrochemical behavior of precipitate phases that may occupy grain and sub-grain boundaries in AA2099. The grain boundary micro-chemistry and micro-electrochemistry have been alluded to within the literature as having significant influence on the SCC behavior of Al-Li-Cu alloys. Major precipitates found in this alloy system are T1 (Al 2CuLi), T2 (Al7.5Cu4Li), T B (Al6CuLi3), and theta (Al2 Cu). These phases were produced in bulk form so that the electrochemical nature of each phase could be characterized. It was determined T1 was most active electrochemically and theta was least. When present on grain boundaries in the alloy, electrochemical behavior of the individual precipitates aligned with the observed corrosion behavior of the alloy (e.g. TB was accompanied by general pitting corrosion and T 1 was accompanied by intergranular corrosion attack). In addition to the electrochemical behavior of

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

Beryllium-aluminum alloys for investment castings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nachtrab, W.T.; Levoy, N.

1997-05-01

Beryllium-aluminum alloys containing greater than 60 wt % beryllium are very favorable materials for applications requiring light weight and high stiffness. However, when produced by traditional powder metallurgical methods, these alloys are expensive and have limited applications. To reduce the cost of making beryllium-aluminum components, Nuclear Metals Inc. (NMI) and Lockheed Martin Electronics and Missiles have recently developed a family of patented beryllium-aluminum alloys that can be investment cast. Designated Beralcast, the alloys can achieve substantial weight savings because of their high specific strength and stiffness. In some cases, weight has been reduced by up to 50% over aluminum investmentmore » casting. Beralcast is now being used to make thin wall precision investment castings for several advanced aerospace applications, such as the RAH-66 Comanche helicopter and F-22 jet fighter. This article discusses alloy compositions, properties, casting method, and the effects of cobalt additions on strength.« less

Reduced-Pressure Foaming of Aluminum Alloys

NASA Astrophysics Data System (ADS)

Vinod Kumar, G. S.; Mukherjee, M.; Garcia-Moreno, F.; Banhart, J.

2013-01-01

We developed a novel process for foaming aluminum and its alloys without using a blowing agent. The process involves a designated apparatus in which molten aluminum and its alloys are first foamed under reduced pressure and then solidified quickly. Foaming was done for pure aluminum (99.99 pct) and AlMg5 alloy not containing stabilizing particles and AlMg5 and AlSi9Mg5 alloys containing 5 vol pct SiO2 particles. We discuss the foaming mechanism and develop a model for estimating the porosity that can be achieved in this process. The nucleation of pores in foams is also discussed.

Precision forging technology for aluminum alloy

NASA Astrophysics Data System (ADS)

Deng, Lei; Wang, Xinyun; Jin, Junsong; Xia, Juchen

2018-03-01

Aluminum alloy is a preferred metal material for lightweight part manufacturing in aerospace, automobile, and weapon industries due to its good physical properties, such as low density, high specific strength, and good corrosion resistance. However, during forging processes, underfilling, folding, broken streamline, crack, coarse grain, and other macro- or microdefects are easily generated because of the deformation characteristics of aluminum alloys, including narrow forgeable temperature region, fast heat dissipation to dies, strong adhesion, high strain rate sensitivity, and large flow resistance. Thus, it is seriously restricted for the forged part to obtain precision shape and enhanced property. In this paper, progresses in precision forging technologies of aluminum alloy parts were reviewed. Several advanced precision forging technologies have been developed, including closed die forging, isothermal die forging, local loading forging, metal flow forging with relief cavity, auxiliary force or vibration loading, casting-forging hybrid forming, and stamping-forging hybrid forming. High-precision aluminum alloy parts can be realized by controlling the forging processes and parameters or combining precision forging technologies with other forming technologies. The development of these technologies is beneficial to promote the application of aluminum alloys in manufacturing of lightweight parts.

Rapid Solidification of a New Generation Aluminum-Lithium Alloy via Electrospark Deposition

NASA Astrophysics Data System (ADS)

Heard, David W.; Boselli, Julien; Gauvin, Raynald; Brochu, Mathieu

Electrospark deposition (ESD) is a rapid solidification processing technique capable of depositing a metal onto a conductive substrate. The short pulse duration and high pulse frequency, combined with the small amount of material transferred during each pulse, results in high cooling rates being realized, on the order of 105-106 C/sec. This study investigates the ability to induce solute trapping behavior, for a new generation aluminum-lithium alloy, AA2199, using ESD.

Nanoprecipitates and Their Strengthening Behavior in Al-Mg-Si Alloy During the Aging Process

NASA Astrophysics Data System (ADS)

Li, Hui; Liu, Wenqing

2017-04-01

The different nanoprecipitates formed in a 6061 aluminum alloy during aging at 453 K (180 °C), with or without 168 hours of pre-natural aging (NA), and the age-hardening response of the alloy were investigated by atom probe tomography (APT) and hardness testing. A hardness plateau developed between 2 and 8 hours in both the artificial aging (AA) and artificial aging with pre-natural aging (NAAA) samples. The hardness of NAAA samples was lower than that of AA samples when artificially aged for the same time. A 168-hour NA led to the formation of solute atom clusters in the matrix. The NA accelerated the precipitation kinetics of the following AA. The solute atom clusters gave the highest hardness increment per unit volume fraction. The β″ precipitates were dominant in the samples at the hardness plateau. The average normalized Mg:Si ratios of the solute atom clusters and GP zones were near 1. The average Mg:Si ratio of β″ precipitates increased from 1.3 to 1.5 upon aging for 2 hours. The microstructural evolution of samples with or without NA and its influence on the strengthening effects are discussed based on the experimental results.

Numerical Simulation of Ballistic Impact of Layered Aluminum Nitride Ceramic

DTIC Science & Technology

2015-09-01

tile(s) Aluminum nitride (AlN) 163 a Polymer layers Polyurethane foam 18 b Backing metal Aluminum 6061-T6 (Al) 23 c Projectile Tungsten heavy alloy...larger (a factor of 3.8) than the most dense polyurethane foam of the available constitutive models. Default options for element failure were imposed in...AlN), a polycrystalline ceramic. The total thickness of the tile(s) is 38.1 mm in all cases. A thin polyurethane laminate separates neighboring tiles

Uniform Corrosion and General Dissolution of Aluminum Alloys 2024-T3, 6061-T6, and 7075-T6

NASA Astrophysics Data System (ADS)

Huang, I.-Wen

Uniform corrosion and general dissolution of aluminum alloys was not as well-studied in the past, although it was known for causing significant amount of weight loss. This work comprises four chapters to understand uniform corrosion of aluminum alloys 2024-T3, 6061-T6, and 7075-T6. A preliminary weight loss experiment was performed for distinguishing corrosion induced weight loss attributed to uniform corrosion and pitting corrosion. The result suggested that uniform corrosion generated a greater mass loss than pitting corrosion. First, to understand uniform corrosion mechanism and kinetics in different environments, a series of static immersion tests in NaCl solutions were performed to provide quantitative measurement of uniform corrosion. Thereafter, uniform corrosion development as a function of temperature, pH, Cl-, and time was investigated to understand the influence of environmental factors. Faster uniform corrosion rate has been found at lower temperature (20 and 40°C) than at higher temperature (60 and 80°C) due to accelerated corrosion product formation at high temperatures inhibiting corrosion reactions. Electrochemical tests including along with scanning electron microscopy (SEM) were utilized to study the temperature effect. Second, in order to further understand the uniform corrosion influence on pit growth kinetics, a long term exposures for 180 days in both immersion and ASTM-B117 test were performed. Uniform corrosion induced surface recession was found to have limited impact on pit geometry regardless of exposure methods. It was also found that the competition for limited cathodic current from uniform corrosion the primary rate limiting factor for pit growth. Very large pits were found after uniform corrosion growth reached a plateau due to corrosion product coverage. Also, optical microscopy and focused ion beam (FIB) imaging has provided more insights of distinctive pitting geometry and subsurface damages found from immersion samples and B117

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.

Crack Repair in Aerospace Aluminum Alloy Panels by Cold Spray

NASA Astrophysics Data System (ADS)

Cavaliere, P.; Silvello, A.

2017-04-01

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.

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

Effect of processing parameters on the corrosion behaviour of friction stir processed AA 2219 aluminum alloy

NASA Astrophysics Data System (ADS)

Surekha, K.; Murty, B. S.; Prasad Rao, K.

2009-04-01

The effect of processing parameters (rotation speed and traverse speed) on the corrosion behaviour of friction stir processed high strength precipitation hardenable AA 2219-T87 alloy was investigated. The results indicate that the rotation speed has a major influence in determining the rate of corrosion, which is attributed to the breaking down and dissolution of the intermetallic particles. Corrosion resistance of friction stir processed alloy was studied by potentiodynamic polarization, electrochemical impedance spectroscopy, salt spray and immersion tests.

[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.

Synthesizing Aluminum alloys by double mechanical alloying

NASA Astrophysics Data System (ADS)

Froyen, L.; Delaey, L.; Niu, X. P.; Le Brun, P.; Peytour, C.

1995-03-01

A new synthesis technique, namely double mechanical alloying (dMA), has been developed to fabricate aluminum alloys containing the finely distributed intermetallic compounds and inert dispersoids Al4C3 and Al2O3 The technique consists mainly of three steps: a primary milling stage of elemental powders (MAI) followed by a heat treatment to promote the formation of intermetallic phases, a secondary milling stage (MA2) to refine the microstructure, and consolidation of the produced powders. The results of mechanical and tribological properties of the resulting materials indicate that the dMA is a promising technique for the fabrication of aluminum alloys for applications requiring wear resistance and high-temperature performance.

Higher Magnification Imaging of the Polished Aluminum Collector Returned from the Genesis Mission

NASA Technical Reports Server (NTRS)

Rodriquez, Melissa C.; Burkett, P. J.; Allton, J. H.

2011-01-01

The polished aluminum collector (previously referred to as the polished aluminum kidney) was intended for noble gas analysis for the Gene-sis mission. The aluminum collector, fabricated from alloy 6061T, was polished for flight with alumina, then diamond paste. Final cleaning was performed by soak-ing and rinsing with hexane, then isopropanol, and last-ly megasonically energized ultrapure water prior to installation. It was mounted inside the collector canister on the thermal shield at JSC in 2000. The polished aluminum collector was not surveyed microscopically prior to flight.

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.

Evaluation Of Four Welding Arc Processes Applied To 6061 Aluminium Alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benoit, A.; Laboratoire de Genie des Materiaux et Procedes Associes; Paillard, P.

At a time when greenhouse gas emissions must be reduced, the use of the aluminium alloys is expanding, in particular in the transportation industry. In order to extend the possibilities of aluminium assembly design, new Metal Inert Gas (MIG) welding processes have been conceived. They work at lower temperatures than usual arc processes (classic MIG or Tungsten Inert Gas). This study compares four arc welding processes, applied to the 6061 aluminium alloy. These four weld processes have been studied through the metallurgical analysis of the weld beads. Metallography, micro-hardness testings, X Ray radiography have been carried out on the producedmore » weld beads. The processes are classified according to the quality of the beads like geometry of beads, size of the heat affected zone and presence of defects.« less

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.

Interfacial Reaction During Dissimilar Joining of Aluminum Alloy to Magnesium and Titanium Alloys

NASA Astrophysics Data System (ADS)

Robson, J. D.; Panteli, A.; Zhang, C. Q.; Baptiste, D.; Cai, E.; Prangnell, P. B.

Ultrasonic welding (USW), a solid state joining process, has been used to produce welds between AA6111 aluminum alloy and AZ31 magnesium alloys or titanium alloy Ti-6Al-4V. The mechanical properties of the welds have been assessed and it has been shown that it is the nature and thickness of the intermetallic compounds (IMCs) at the joint line that are critical in determining joint strength and particularly fracture energy. Al-Mg welds suffer from a very low fracture energy, even when strength is comparable with that of similar metal Mg-Mg welds, due to a thick IMC layer always being formed. It is demonstrated that in USW of Al-Ti alloy the slow interdiffusion kinetics means that an IMC layer does not form during welding, and fracture energy is greater. A model has been developed to predict IMC formation during welding and provide an understanding of the critical factors that determine the IMC thickness. It is predicted that in Al-Mg welds, most of the lMC thickening occurs whilst the IMC regions grow as separate islands, prior to the formation of a continuous layer.

Constitutive Behavior and Deep Drawability of Three Aluminum Alloys Under Different Temperatures and Deformation Speeds

NASA Astrophysics Data System (ADS)

Panicker, Sudhy S.; Prasad, K. Sajun; Basak, Shamik; Panda, Sushanta Kumar

2017-08-01

In the present work, uniaxial tensile tests were carried out to evaluate the stress-strain response of AA2014, AA5052 and AA6082 aluminum alloys at four temperatures: 303, 423, 523 and 623 K, and three strain rates: 0.0022, 0.022 and 0.22 s-1. It was found that the Cowper-Symonds model was not a robust constitutive model, and it failed to predict the flow behavior, particularly the thermal softening at higher temperatures. Subsequently, a comparative study was made on the capability of Johnson-Cook (JC), modified Zerilli-Armstrong (m-ZA), modified Arrhenius (m-ARR) and artificial neural network (ANN) for modeling the constitutive behavior of all the three aluminum alloys under the mentioned strain rates and temperatures. Also, the improvement in formability of the materials was evaluated at an elevated temperature of 623 K in terms of cup height and maximum safe strains by conducting cylindrical cup deep drawing experiments under two different punch speeds of 4 and 400 mm/min. The cup heights increased during warm deep drawing due to thermal softening and increase in failure strains. Also, a small reduction in cup height was observed when the punch speed increased from 4 to 400 mm/min at 623 K. Hence, it was suggested to use high-speed deformation at elevated temperature to reduce both punch load and cycle time during the deep drawing process.

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

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.

Microstructural analysis of as-processed U-10 wt.%Mo monolithic fuel plate in AA6061 matrix with Zr diffusion barrier

NASA Astrophysics Data System (ADS)

Perez, E.; Yao, B.; Keiser, D. D., Jr.; Sohn, Y. H.

2010-07-01

For higher U-loading in low-enriched U-10 wt.%Mo fuels, monolithic fuel plate clad in AA6061 is being developed as a part of Reduced Enrichment for Research and Test Reactor (RERTR) program. This paper reports the first characterization results from a monolithic U-10 wt.%Mo fuel plate with a Zr diffusion barrier that was fabricated as part of a plate fabrication campaign for irradiation testing in the Advanced Test Reactor (ATR). Both scanning and transmission electron microscopy (SEM and TEM) were employed for analysis. At the interface between the Zr barrier and U-10 wt.%Mo, going from Zr to U(Mo), UZr 2, γ-UZr, Zr solid-solution and Mo 2Zr phases were observed. The interface between AA6061 cladding and Zr barrier plate consisted of four layers, going from Al to Zr, (Al, Si) 2Zr, (Al, Si)Zr 3 (Al, Si) 3Zr, and AlSi 4Zr 5. Irradiation behavior of these intermetallic phases is discussed based on their constituents. Characterization of as-fabricated phase constituents and microstructure would help understand the irradiation behavior of these fuel plates, interpret post-irradiation examination, and optimize the processing parameters of monolithic fuel system.

Experimental and numerical investigation of strain rate effect on low cycle fatigue behaviour of AA 5754 alloy

NASA Astrophysics Data System (ADS)

Kumar, P.; Singh, A.

2018-04-01

The present study deals with evaluation of low cycle fatigue (LCF) behavior of aluminum alloy 5754 (AA 5754) at different strain rates. This alloy has magnesium (Mg) as main alloying element (Al-Mg alloy) which makes this alloy suitable for Marines and Cryogenics applications. The testing procedure and specimen preparation are guided by ASTM E606 standard. The tests are performed at 0.5% strain amplitude with three different strain rates i.e. 0.5×10-3 sec-1, 1×10-3 sec-1 and 2×10-3 sec-1 thus the frequency of tests vary accordingly. The experimental results show that there is significant decrease in the fatigue life with the increase in strain rate. LCF behavior of AA 5754 is also simulated at different strain rates by finite element method. Chaboche kinematic hardening cyclic plasticity model is used for simulating the hardening behavior of the material. Axisymmetric finite element model is created to reduce the computational cost of the simulation. The material coefficients used for “Chaboche Model” are determined by experimentally obtained stabilized hysteresis loop. The results obtained from finite element simulation are compared with those obtained through LCF experiments.

Fatigue crack propagation in aluminum-lithium alloys

NASA Technical Reports Server (NTRS)

Rao, K. T. V.; Ritchie, R. O.; Piascik, R. S.; Gangloff, R. P.

1989-01-01

The principal mechanisms which govern the fatigue crack propagation resistance of aluminum-lithium alloys are investigated, with emphasis on their behavior in controlled gaseous and aqueous environments. Extensive data describe the growth kinetics of fatigue cracks in ingot metallurgy Al-Li alloys 2090, 2091, 8090, and 8091 and in powder metallurgy alloys exposed to moist air. Results are compared with data for traditional aluminum alloys 2024, 2124, 2618, 7075, and 7150. Crack growth is found to be dominated by shielding from tortuous crack paths and resultant asperity wedging. Beneficial shielding is minimized for small cracks, for high stress ratios, and for certain loading spectra. While water vapor and aqueous chloride environments enhance crack propagation, Al-Li-Cu alloys behave similarly to 2000-series aluminum alloys. Cracking in water vapor is controlled by hydrogen embrittlement, with surface films having little influence on cyclic plasticity.

Spectral Dependence of Stratified Electrothermal Instability in Tamped Aluminum 6061 with Current in a Skin Layer

NASA Astrophysics Data System (ADS)

Bauer, Bruno; Hutchinson, Trevor; Awe, Thomas

2017-10-01

The stratified electrothermal instability (ETI) was recently observed on the surface of thick aluminum 6061 pulsed with rapidly rising lineal current density (3 ×1015 A m-1s-1) for 70 ns. A transparent 70- μm-thick Parylene-N coating tamped the aluminum expansion and suppressed surface plasma. The evolution of the aluminum surface emission pattern was recorded with time-resolved microscopy (3- μm resolution). The images were converted into a series of blackbody surface-temperature maps. Analysis of these temperature maps provides information on the evolution of temperature fluctuations, as a function of axial wavelength and azimuthal width. Perturbations with axial wavelength longer than 20 μm grow, while those with axial wavelength shorter than 10 μm decay. Comparing the spectral dependence of growth/decay rates with MHD simulations could test the modeling of ETI positive feedback and of damping by thermal conduction. Work supported by Sandia National Laboratories LDRD program, PO 1742766.

Constitutive behavior of as-cast AA1050, AA3104, and AA5182

NASA Astrophysics Data System (ADS)

van Haaften, W. M.; Magnin, B.; Kool, W. H.; Katgerman, L.

2002-07-01

Recent thermomechanical modeling to calculate the stress field in industrially direct-chill (DC) cast-aluminum slabs has been successful, but lack of material data limits the accuracy of these calculations. Therefore, the constitutive behavior of three aluminum alloys (AA1050, AA3104, and AA5182) was determined in the as-cast condition using tensile tests at low strain rates and from room temperature to solidus temperature. The parameters of two constitutive equations, the extended Ludwik equation and a combination of the Sellars-Tegart equation with a hardening law, were determined. In order to study the effect of recovery, the constitutive behavior after prestraining at higher temperatures was also investigated. To evaluate the quantified constitutive equations, tensile tests were performed simulating the deformation and cooling history experienced by the material during casting. It is concluded that both constitutive equations perform well, but the combined hardening-Sellars-Tegart (HST) equation has temperature-independent parameters, which makes it easier to implement in a DC casting model. Further, the deformation history of the ingot should be taken into account for accurate stress calculations.

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.

Microstructural characterization and mechanical property of active soldering anodized 6061 Al alloy using Sn-3.5Ag-xTi active solders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Wei-Lin, E-mail: wangwl77@gmail.com; Tsai, Yi-Chia, E-mail: tij@itri.org.tw

2012-06-15

Active solders Sn-3.5Ag-xTi varied from x = 0 to 6 wt.% Ti addition were prepared by vacuum arc re-melting and the resultant phase formation and variation of microstructure with titanium concentration were analyzed using X-ray diffraction, optical microscopy and scanning electron microscopy. The Sn-3.5Ag-xTi active solders are used as metallic filler to join with anodized 6061 Al alloy for potential applications of providing a higher heat conduction path. Their joints and mechanical properties were characterized and evaluated in terms of titanium content. The mechanical property of joints was measured by shear testing. The joint strength was very dependent on themore » titanium content. Solder with a 0.5 wt.% Ti addition can successfully wet and bond to the anodized aluminum oxide layers of Al alloy and posses a shear strength of 16.28 {+-} 0.64 MPa. The maximum bonding strength reached 22.24 {+-} 0.70 MPa at a 3 wt.% Ti addition. Interfacial reaction phase and chemical composition were identified by a transmission electron microscope with energy dispersive spectrometer. Results showed that the Ti element reacts with anodized aluminum oxide to form Al{sub 3}Ti-rich and Al{sub 3}Ti phases at the joint interfaces. - Highlights: Black-Right-Pointing-Pointer Active solder joining of anodized Al alloy needs 0.5 wt.% Ti addition for Sn-3.5Ag. Black-Right-Pointing-Pointer The maximum bonding strength occurs at 3 wt.% Ti addition. Black-Right-Pointing-Pointer The Ti reacts with anodized Al oxide to form Al{sub 3}Ti-rich and Al{sub 3}Ti at joint interface.« less

An Improvement of the Anisotropy and Formability Predictions of Aluminum Alloy Sheets

NASA Astrophysics Data System (ADS)

Banabic, D.; Comsa, D. S.; Jurco, P.; Wagner, S.; Vos, M.

2004-06-01

The paper presents an yield criterion for orthotropic sheet metals and its implementation in a theoretical model in order to calculate the Forming Limit Curves. The proposed yield criterion has been validated for two aluminum alloys: AA3103-0 and AA5182-0, respectively. The biaxial tensile test of cross specimens has been used for the determination of the experimental yield locus. The new yield criterion has been implemented in the Marciniak-Kuczynski model for the calculus of limit strains. The calculated Forming Limit Curves have been compared with the experimental ones, determined by frictionless test: bulge test, plane strain test and uniaxial tensile test. The predicted Forming Limit Curves using the new yield criterion are in good agreement with the experimental ones.

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.

The Effects of Specimen Geometry on the Plastic Deformation of AA 2219-T8 Aluminum Alloy Under Dynamic Impact Loading

NASA Astrophysics Data System (ADS)

Owolabi, G. M.; Bolling, D. T.; Odeshi, A. G.; Whitworth, H. A.; Yilmaz, N.; Zeytinci, A.

2017-12-01

The effects of specimen geometry on shear strain localization in AA 2219-T8 aluminum alloy under dynamic impact loading were investigated. The alloy was machined into cylindrical, cuboidal and conical (frustum) test specimens. Both deformed and transformed adiabatic shear bands developed in the alloy during the impact loading. The critical strain rate for formation of the deformed band was determined to be 2500 s-1 irrespective of the specimen geometry. The critical strain rate required for formation of transformed band is higher than 3000 s-1 depending on the specimen geometry. The critical strain rate for formation of transformed bands is lowest (3000 s-1) in the Ø5 mm × 5 mm cylindrical specimens and highest (> 6000 s-1) in the conical specimens. The cylindrical specimens showed the greatest tendency to form transformed bands, whereas the conical specimen showed the least tendency. The shape of the shear bands on the impacted plane was also observed to be dependent on the specimen geometry. Whereas the shear bands on the compression plane of the conical specimens formed elongated cycles, two elliptical shaped shear bands facing each other were observed on the cylindrical specimens. Two parallel shear bands were observed on the compression planes of the cuboidal specimens. The dynamic stress-strain curves vary slightly with the specimen geometry. The cuboidal specimens exhibit higher tendency for strain hardening and higher maximum flow stress than the other specimens. The microstructure evolution leading to the formation of transformed bands is also discussed in this paper.

A Process for Producing Highly Wettable Aluminum 6061 Surfaces Compatible with Hydrazine

NASA Technical Reports Server (NTRS)

Moore, N. R.; Ferraro, N. W.; Yue, A. F.; Estes, R. H.

2007-01-01

NASA's Global Precipitation Measurement (GPM) mission is an ongoing Goddard Space Flight Center (GSFC) project whose basic objective is to improve global precipitation measurements. The space-based portion of the mission architecture consists of a primary or core spacecraft and a constellation of NASA and contributed spacecrafts. The efforts described in this paper refer to the core spacecraft (hereafter referred to as simply GPM) which is to be fabricated at GSFC. It has been decided that the GPM spacecraft is to be a "design-for-demise-spacecraft." This requirement resulted in the need for a propellant tank that would also demise or ablate to an appropriate degree upon re-entry. Composite overwrapped aluminum lined propellant tanks with aluminum propellant management devices (PMD) were shown by analyses to demise and thus became the baseline configuration for GPM. As part of the GPM tank development effort, long term compatibility and wettability testing with hydrazine was performed on Al6061 and 2219 coupons fabricated and cleaned by conventional processes. Long term compatibility was confirmed. However, the wettability of the aluminum as measured by contact angle produced higher than desired angles (greater than 30 deg.) with excessive scatter. The availability of PMD materials exhibiting consistently low contact angles aids in the design of simple PMDs. Two efforts performed by Angeles Crest Engineering and funded by GSFC were undertaken to reduce the risk of using aluminum for the GPM PMD. The goal of the first effort was to develop a cleaning or treatment process to produce consistently low contact angles. The goal of the second effort was to prove via testing that the processed aluminum would retain compatibility with hydrazine and retain low contact angle after long term exposure to hydrazine. Both goals were achieved. This paper describes both efforts and the results achieved.

Charge-density-shear-moduli relationships in aluminum-lithium alloys.

PubMed

Eberhart, M

2001-11-12

Using the first principles full-potential linear-augmented-Slater-type orbital technique, the energies and charge densities of aluminum and aluminum-lithium supercells have been computed. The experimentally observed increase in aluminum's shear moduli upon alloying with lithium is argued to be the result of predictable changes to aluminum's total charge density, suggesting that simple rules may allow the alloy designer to predict the effects of dilute substitutional elements on alloy elastic response.

The Ballistic and Corrosion Evaluation of Magnesium Elektron E675 vs. Baseline Magnesium Alloy AZ31B and Aluminum Alloy 5083 for Armor Applications

DTIC Science & Technology

2011-06-01

critical property in reducing the plastic failure of the material. The ductility is marginally better than Mg AZ31B. 2 Table 1. Chemical...composition (%) of metal alloys. Element (%)/Alloy CPMg 9980B AZ31B-H24 AA5083-H131 Aluminum — 2.5–3.5 REM Manganese 0.10 max 0.2–1.0 0.40‒1.0 Zinc — 0.6...This trend was attributed to the lack of ductility in E675 compared to 5083, which reduced energy dissipation. Visual analysis of the Mg E675

Microstructural features of friction stir welded dissimilar Aluminium alloys AA2219-AA7475

NASA Astrophysics Data System (ADS)

Zaman Khan, Noor; Ubaid, Mohammed; Siddiquee, Arshad Noor; Khan, Zahid A.; Al-Ahmari, Abdulrahman; Chen, Xizhang; Haider Abidi, Mustufa

2018-05-01

High strength, good corrosion resistance, light weight make aluminium alloys a material of choice in many industrial sectors like aerospace, marine etc. Problems associated with welding of these alloys by fusion welding processes restricted their use in various industries. Friction stir welding (FSW), a clean solid-state joining process, easily overcomes various difficulties encountered during conventional fusion welding processes. In the present work, the effect of rotational speed (710 rpm, 900 rpm and 1120 rpm) on micro-hardness distribution and microstructure of FSWed dissimilar aluminium alloy joints were analyzed. Plates of AA7475-T761 and AA2219-O having thickness of 2.5 mm were welded by fixing AA7475 on retreating side (RS) and AA2219 on advancing side (AS). Welded joints were characterized by Vickers micro-hardness testing, scanning electron microscopy (SEM) and optical microscopy (OM). Results revealed that rotational speed significantly affects the micro-hardness due to increase in grain size, coarsening and dissolution of strengthening precipitates and re-precipitation. Higher micro-hardness values were observed in stir zone due to grain refinement and re-precipitation. Minimum micro-hardness value was observed at the TMAZ/HAZ of advancing side due to thermal softening.

Reinforcing aluminum alloys with high strength fibers

NASA Technical Reports Server (NTRS)

Kolpashnikov, A. I.; Manuylov, V. F.; Chukhin, B. D.; Shiryayev, Y. V.; Shurygin, A. S.

1982-01-01

A study is made of the possibility of reinforcing aluminum and aluminum based alloys with fibers made of high strength steel wire. The method of introducing the fibers is described in detail. Additional strengthening by reinforcement of the high alloy system Al - An - Mg was investigated.

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.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 weldmore » 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).« less

Microstructures and properties of aluminum die casting alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

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.

Cavitation pitting and erosion of aluminum 6061-T6 in mineral oil water

NASA Technical Reports Server (NTRS)

Rao, B. C. S.; Buckley, D. H.

1983-01-01

Cavitation erosion studies of aluminum 6061-T6 in mineral oil and in ordinary tap water are presented. The maximum erosion rate (MDPR, or mean depth of penetration rate) in mineral oil was about four times that in water. The MDPR in mineral oil decreased continuously with time, but the MDPR in water remained approximately constant. The cavitation pits in mineral oil were of smaller diameter and depth than the pits in water. Treating the pits as spherical segments, we computed the radius r of the sphere. The logarithm of h/a, where h is the pit depth and 2a is the top width of the pit, was linear when plotted against the logarithm of 2r/h - 1.

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.

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.

Initial Subdivision of Genesis Early Science Polished Aluminum Collector

NASA Technical Reports Server (NTRS)

Allton, J. H.; Stansbery, E. K.; McNamara, K. M.; Meshik, A.; See, T. H.; Bastien, R.

2005-01-01

A large surface, about 245 square centimeters, of highly polished aluminum 6061 T6 alloy was attached to the science canister thermal panel for the purpose of collecting solar wind noble gases. The analysis of this collector will be part of the Genesis Early Science results. The pre-launch configuration of the collector is shown. The collector sustained some damage during the recovery impact in Utah, September 8, 2004.

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.

Microstructural-Scale Model for Surfaces Spreading of Intergranular Corrosion in Sensitized Stainless Steels and Aluminum-Magnesium (AA5XXX) Alloys

NASA Astrophysics Data System (ADS)

Jain, Swati

Components from AA5XXX (Al-Mg alloys with more than 3 wt% Mg) alloys are X attractive due to availability of low cost, high strength to weight ratio and good weldability. Therefore, these alloys have potential applications in Naval ships. However, these alloys become susceptible to IGC (intergranular corrosion) due to beta-phase precipitation due to improper heat treatment or inadvertent thermal exposure. Stainless steels may also become susceptible due to carbide precipitation and chromium depletion on grain boundaries. IGC susceptibility depends on the interplay between the metallurgical conditions, electrochemical conditions, and chemical conditions. Specific combinations cause IGC while others do not. The objective of this study is to investigate the conditions which bring about surface spreading of IGC in these alloy classes. To accomplish this goal, a microstructure scale model was developed with experimental inputs to understand the 2-D IGC spreading in stainless steels and AA5XXX alloys. The conditions strongly affecting IGC spreading were elucidated. Upon natural and artificial aging, the stainless steels become susceptible to intergranular corrosion because of chromium depletion in the grain boundaries. After aging Al-Mg (AA5XXX) alloys show susceptibility due to the precipitation of the beta-phase (Al3Mg7) in the grain boundaries. Chromium depleted grain boundaries in stainless steels are anodically more active as compared to the interior of the grains. (3-phase rich grain boundaries have lower OCP (open circuit potential) and pitting potentials as compared to the Al-Mg solid solutions. A new approach to modeling the IGC surface spreading in polycrystalline materials that is presented. This model is the first to couple several factors into one granular scale model that illustrates the way in which they interact and IGC occurs. It sheds new information on conditions which cause IGC spreading in two alloy classes and describes a new theory for the critical

Microstructure and wear characterization of aluminum matrix composites reinforced with industrial waste fly ash particulates synthesized by friction stir processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dinaharan, I., E-mail: dinaweld2009@gmail.com

Fly ash (FA) is a waste product of coal combustion in thermal power plants which is available in massive quantities all over the world causing land pollution. This paper reports the characterization of AA6061 aluminum matrix composites (AMCs) reinforced with FA particles synthesized using friction stir processing (FSP). The volume fraction of FA particles was varied from 0 to 18 in steps of 6. The prepared AMCs were characterized using optical microscopy (OM), scanning electron microscopy (SEM) and electron backscattered diagram (EBSD). The wear rate was estimated using a pin-on-disc wear apparatus. FA particles were observed to be distributed homogeneouslymore » in the AMC irrespective of the location within the stir zone. The EBSD micrographs revealed remarkable grain refinement in the AMC. The incorporation of FA particles enhanced the microhardness and wear resistance of the AMC. The strengthening mechanisms of the AMC were discussed and correlated to the observed microstructures. The wear mechanisms were identified by characterizing the wear debris and worn surfaces. - Highlights: •Industrial waste fly ash was used to produce aluminum matrix composites. •Friction stir processing was used to produce AA6061/Fly Ash composite. •Fly ash particles refined the grains of aluminum matrix. •Fly ash particles enhanced the hardness and wear resistance. •Successful utilization of fly ash to make aluminum composites reduces land pollution.« less

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.

Influence of Welding Process and Post Weld Heat Treatment on Microstructure and Pitting Corrosion Behavior of Dissimilar Aluminium Alloy Welds

NASA Astrophysics Data System (ADS)

Venkata Ramana, V. S. N.; Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

2018-03-01

Welding of dissimilar Aluminum alloy welds is becoming important in aerospace, shipbuilding and defence applications. In the present work, an attempt has been made to weld dissimilar aluminium alloys using conventional gas tungsten arc welding (GTAW) and friction stir welding (FSW) processes. An attempt was also made to study the effect of post weld heat treatment (T4 condition) on microstructure and pitting corrosion behaviour of these welds. Results of the present investigation established the differences in microstructures of the base metals in T4 condition and in annealed conditions. It is evident that the thickness of the PMZ is relatively more on AA2014 side than that of AA6061 side. In FS welds, lamellar like shear bands are well noticed on the top of the stir zone. The concentration profile of dissimilar friction stir weld in T4 condition revealed that no diffusion has taken place at the interface. Poor Hardness is observed in all regions of FS welds compared to that of GTA welds. Pitting corrosion resistance of the dissimilar FS welds in all regions was improved by post weld heat treatment.

Finite Element Simulation of Temperature and Strain Distribution during Friction Stir Welding of AA2024 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Jain, Rahul; Pal, Surjya Kanta; Singh, Shiv Brat

2017-02-01

Friction Stir Welding (FSW) is a solid state joining process and is handy for welding aluminum alloys. Finite Element Method (FEM) is an important tool to predict state variables of the process but numerical simulation of FSW is highly complex due to non-linear contact interactions between tool and work piece and interdependency of displacement and temperature. In the present work, a three dimensional coupled thermo-mechanical method based on Lagrangian implicit method is proposed to study the thermal history, strain distribution and thermo-mechanical process in butt welding of Aluminum alloy 2024 using DEFORM-3D software. Workpiece is defined as rigid-visco plastic material and sticking condition between tool and work piece is defined. Adaptive re-meshing is used to tackle high mesh distortion. Effect of tool rotational and welding speed on plastic strain is studied and insight is given on asymmetric nature of FSW process. Temperature distribution on the workpiece and tool is predicted and maximum temperature is found in workpiece top surface.

Corrosion of aluminum alloys by chlorinated hydrocarbon/methanol mixtures

NASA Technical Reports Server (NTRS)

De Forest, W. S.

1967-01-01

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

Stress Corrosion Cracking of Certain Aluminum Alloys

NASA Technical Reports Server (NTRS)

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

1983-01-01

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

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.

Improving Joint Formation and Tensile Properties of Dissimilar Friction Stir Welding of Aluminum and Magnesium Alloys by Solving the Pin Adhesion Problem

NASA Astrophysics Data System (ADS)

Liu, Zhenlei; Ji, Shude; Meng, Xiangchen

2018-03-01

Friction stir welding (FSW), as a solid-state welding technology invented by TWI in 1991, has potential to join dissimilar Al/Mg alloys. In this study, the pin adhesion phenomenon affecting joint quality during FSW of 6061-T6 aluminum and AZ31B magnesium alloys was investigated. The adhesion phenomenon induced by higher heat input easily transformed the tapered-and-screwed pin into a tapered pin, which greatly reduced the tool's ability to drive the plasticized materials and further deteriorated joint formation. Under the condition without the pin adhesion, the complex intercalated interlayer at the bottom of stir zone was beneficial to mechanical interlocking of Al/Mg alloys, improving tensile properties. However, the formation of intermetallic compounds was still the main reason of the joint fracture, significantly deteriorating tensile properties. Under the welding speed of 60 mm/min without the pin adhesion phenomenon, the maximum tensile strength of 107 MPa and elongation of 1.2% were achieved.

Growth kinetics and microstructural evolution during hot isostatic pressing of U-10 wt.% Mo monolithic fuel plate in AA6061 cladding with Zr diffusion barrier

NASA Astrophysics Data System (ADS)

Park, Y.; Yoo, J.; Huang, K.; Keiser, D. D.; Jue, J. F.; Rabin, B.; Moore, G.; Sohn, Y. H.

2014-04-01

Phase constituents and microstructure changes in RERTR fuel plate assemblies as functions of temperature and duration of hot-isostatic pressing (HIP) during fabrication were examined. The HIP process was carried out as functions of temperature (520, 540, 560 and 580 °C for 90 min) and time (45-345 min at 560 °C) to bond 6061 Al-alloy to the Zr diffusion barrier that had been co-rolled with U-10 wt.% Mo (U10Mo) fuel monolith prior to the HIP process. Scanning and transmission electron microscopies were employed to examine the phase constituents, microstructure and layer thickness of interaction products from interdiffusion. At the interface between the U10Mo and Zr, following the co-rolling, the UZr2 phase was observed to develop adjacent to Zr, and the α-U phase was found between the UZr2 and U10Mo, while the Mo2Zr was found as precipitates mostly within the α-U phase. The phase constituents and thickness of the interaction layer at the U10Mo-Zr interface remained unchanged regardless of HIP processing variation. Observable growth due to HIP was only observed for the (Al,Si)3Zr phase found at the Zr/AA6061 interface, however, with a large activation energy of 457 ± 28 kJ/mole. Thus, HIP can be carried to improve the adhesion quality of fuel plate without concern for the excessive growth of the interaction layer, particularly at the U10Mo-Zr interface with the α-U, Mo2Zr, and UZr2 phases.

Effects of thread interruptions on tool pins in friction stir welding of AA6061

DOE PAGES

Reza-E-Rabby, Md.; Tang, Wei; Reynolds, Anthony P.

2017-06-21

In this paper, effects of pin thread and thread interruptions (flats) on weld quality and process response parameters during friction stir welding (FSW) of 6061 aluminium alloy were quantified. Otherwise, identical smooth and threaded pins with zero to four flats were adopted for FSW. Weldability and process response variables were examined. Results showed that threads with flats significantly improved weld quality and reduced in-plane forces. A three-flat threaded pin led to production of defect-free welds under all examined welding conditions. Spectral analyses of in-plane forces and weld cross-sectional analysis were performed to establish correlation among pin flats, force dynamics andmore » defect formation. Finally, the lowest in-plane force spectra amplitudes were consistently observed for defect-free welds.« less

Effects of thread interruptions on tool pins in friction stir welding of AA6061

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reza-E-Rabby, Md.; Tang, Wei; Reynolds, Anthony P.

In this paper, effects of pin thread and thread interruptions (flats) on weld quality and process response parameters during friction stir welding (FSW) of 6061 aluminium alloy were quantified. Otherwise, identical smooth and threaded pins with zero to four flats were adopted for FSW. Weldability and process response variables were examined. Results showed that threads with flats significantly improved weld quality and reduced in-plane forces. A three-flat threaded pin led to production of defect-free welds under all examined welding conditions. Spectral analyses of in-plane forces and weld cross-sectional analysis were performed to establish correlation among pin flats, force dynamics andmore » defect formation. Finally, the lowest in-plane force spectra amplitudes were consistently observed for defect-free welds.« less

Investigations on Laser Beam Welding of Different Dissimilar Joints of Steel and Aluminum Alloys for Automotive Lightweight Construction

NASA Astrophysics Data System (ADS)

Seffer, Oliver; Pfeifer, Ronny; Springer, André; Kaierle, Stefan

Due to the enormous potential of weight saving, and the consequential reduction of pollutant emissions, the use of hybrid components made of steel and aluminum alloys is increasing steadily, especially concerning automotive lightweight construction. However, thermal joining of steel and aluminum is still being researched, due to a limited solubility of the binary system of iron and aluminum causing the formation of hard and brittle intermetallic phases, which decrease the strength and the formability of the dissimilar seam. The presented results show the investigation of laser beam welding for joining different dissimilar hybrid components of the steel materials HX220LAD+Z100, 22MnB5+AS150 and 1.4301, as well as the aluminum alloy AA6016-T4 as a lap joint. Among other things, the influences of the energy per unit length, the material grade, the sheet thickness t, the weld type (lap weld, fillet weld) and the arrangement of the base materials in a lap joint (aluminum-sided irradiation, steel-sided irradiation) on the achievable strengths are analyzed. The characterization of the dissimilar joints includes tensile shear tests and metallographic analyses, depending on the energy per unit length.

Airborne bacteria associated with corrosion of mild steel 1010 and aluminum alloy 1100.

PubMed

Rajasekar, Aruliah; Xiao, Wang; Sethuraman, Manivannan; Parthipan, Punniyakotti; Elumalai, Punniyakotti

2017-03-01

A novel approach to measure the contribution of airborne bacteria on corrosion effects of mild steel (MS) and aluminum alloy (AA) as a function of their exposure period, and the atmospheric chemical composition was investigated at an urban industrial coastal site, Singapore. The 16S rRNA and phylogenetic analyses showed that Firmicutes are the predominant bacteria detected in AA and MS samples. The dominant bacterial groups identified were Bacillaceae, Staphylococcaceae, and Paenibacillaceae. The growth and proliferation of these bacteria could be due to the presence of humidity and chemical pollutants in the atmosphere, leading to corrosion. Weight loss showed stronger corrosion resistance of AA (1.37 mg/cm 2 ) than MS (26.13 mg/cm 2 ) over the exposure period of 150 days. The higher corrosion rate could be a result of simultaneous action of pollutants and bacterial exopolysaccharides on the metal surfaces. This study demonstrates the significant involvement of airborne bacteria on atmospheric corrosion of engineering materials.

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.

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.

Effect of Thermal Treatment on the Mechanical and Toughness Properties of Extruded Sic sub w/Aluminum 6061 Metal Matrix Composite.

DTIC Science & Technology

1987-01-31

Charpy V-Notch_,,... i9,, STRACT (Continue on reverse if necessary and identify by block number) Mechanical, instrumented\\ Charpy V-potch (CVN) energy and...authors express their appreciation to Messrs. W. Willard and R. Gray for the fracture testing, Ensign M. Rennie for the instrumented Charpy V-notch...TO ALUMINUM GRAIN BOUNDARIES . . . . . . . . . 12 5 INSTRUMENTED CHARPY V-NOTCH LOAD AND ENERGY AGAINST TIME OUTPUTS FOR L-C ORIENTATION SiCwJAI 6061

Modification of Sr on 4004 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Guo, Erjun; Cao, Guojian; Feng, Yicheng; Wang, Liping; Wang, Guojun; Lv, Xinyu

2013-05-01

As a brazing foil, 4004 Al alloy has good welding performance. However, the high Si content decreases the plasticity of the alloy. To improve the plasticity of 4004 Al alloy and subsequently improve the productivity of 4004 Al foil or 434 composite foil, 4004 Al alloy was modified by Al-10%Sr master alloy. Modification effects of an additional amount of Sr, modification temperature, and holding time on 4004 aluminum alloy were studied by orthogonal design. The results showed that the greatest impact parameter of 4004 aluminum alloy modification was the additional amount of Sr, followed by holding time and modification temperature. The optimum modification parameters obtained by orthogonal design were as follows: Sr addition of 0.04%, holding time of 60 min, and modification temperature of 760°C. The effect of Sr addition on modification was analyzed in detail based on orthogonal results. With increasing of Sr addition, elongation of 4004 alloy increased at first, and decreased after reaching the maximum value.

Material characterization and finite element simulations of aluminum alloy sheets during non-isothermal forming process

NASA Astrophysics Data System (ADS)

Zhang, Nan

The utilization of more non-ferrous materials is one of the key factors to succeed out of the constantly increasing demand for lightweight vehicles in automotive sector. Aluminum-magnesium alloys have been identified as the most promising substitutions to the conventional steel without significant compromise in structural stiffness and strength. However, the conventional forming methods to deform the aluminum alloy sheets are either costly or insufficient in formability which limit the wide applications of aluminum alloy sheets. A recently proposed non-isothermal hot stamping approach, which is also referred as Hot Blank - Cold Die (HB-CD) stamping, aims at fitting the commercial grade aluminum alloy sheets, such as AA5XXX and AA7XXX, into high-volume and cost-effective production for automotive sector. In essence, HB-CD is a mutation of the conventional hot stamping approach for boron steel (22MnB5) which deforms the hot blank within the cold tool set. By elevating the operation temperature, the formability of aluminum alloy sheets can be significantly improved. Meanwhile, heating the blank only and deforming within the cold tool sets allow to reduce the energy and time consumed. This research work aims at conducting a comprehensive investigation of HB-CD with particular focuses on material characterization, constitutive modeling and coupled thermo-mechanical finite element simulations with validation. The material properties of AA5182-O, a popular commercial grade of aluminum alloy sheet in automotive sector, are obtained through isothermal tensile testing at temperatures from 25° to 300°, covering a quasi-static strain-rate range (0.001--0.1s-1). As the state-of-the-art non-contact strain measurement technique, digital image correlation (DIC) system is utilized to evaluate the stress-strain curves as well as to reveal the details of material deformation with full-field and multi-axis strain measurement. Material anisotropy is characterized by extracting the

Roll Casting of Aluminum Alloy Clad Strip

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakamura, R.; Tsuge, H.; Haga, T.

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 connectedmore » 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.« less

A computational study of low-head direct chill slab casting of aluminum alloy AA2024

NASA Astrophysics Data System (ADS)

Hasan, Mainul; Begum, Latifa

2016-04-01

The steady state casting of an industrial-sized AA2024 slab has been modeled for a vertical low-head direct chill caster. The previously verified 3-D CFD code is used to investigate the solidification phenomena of the said long-range alloy by varying the pouring temperature, casting speed and the metal-mold contact heat transfer coefficient from 654 to 702 °C, 60-180 mm/min, and 1.0-4.0 kW/(m2 K), respectively. The important predicted results are presented and thoroughly discussed.

Stress Corrosion Cracking Behavior of Multipass TIG-Welded AA2219 Aluminum Alloy in 3.5 wt pct NaCl Solution

NASA Astrophysics Data System (ADS)

Venugopal, A.; Sreekumar, K.; Raja, V. S.

2012-09-01

The stress corrosion cracking (SCC) behavior of the AA2219 aluminum alloy in the single-pass (SP) and multipass (MP) welded conditions was examined and compared with that of the base metal (BM) in 3.5 wt pct NaCl solution using a slow-strain-rate technique (SSRT). The reduction in ductility was used as a parameter to evaluate the SCC susceptibility of both the BM and welded joints. The results showed that the ductility ratio ( ɛ NaCl/( ɛ air) was 0.97 and 0.96, respectively, for the BM and MP welded joint, and the same was marginally reduced to 0.9 for the SP welded joint. The fractographic examination of the failed samples revealed a typical ductile cracking morphology for all the base and welded joints, indicating the good environmental cracking resistance of this alloy under all welded conditions. To understand the decrease in the ductility of the SP welded joint, preexposure SSRT followed by microstructural observations were made, which showed that the decrease in ductility ratio of the SP welded joint was caused by the electrochemical pitting that assisted the nucleation of cracks in the form of corrosion induced mechanical cracking rather than true SCC failure of the alloy. The microstructural examination and polarization tests demonstrated a clear grain boundary (GB) sensitization of the PMZ, resulting in severe galvanic corrosion of the SP weld joint, which initiated the necessary conditions for the localized corrosion and cracking along the PMZ. The absence of PMZ and a refined fusion zone (FZ) structure because of the lesser heat input and postweld heating effect improved the galvanic corrosion resistance of the MP welded joint greatly, and thus, failure occurred along the FZ.

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.

Nondestructive Evaluation of Friction Stir-Welded Aluminum Alloy to Coated Steel Sheet Lap Joint

NASA Astrophysics Data System (ADS)

Das, H.; Kumar, A.; Rajkumar, K. V.; Saravanan, T.; Jayakumar, T.; Pal, Tapan Kumar

2015-11-01

Dissimilar lap joints of aluminum sheet (AA 6061) of 2 mm thickness and zinc-coated steel sheet of 1 mm thickness were produced by friction stir welding with different combinations of rotational speed and travel speed. Ultrasonic C- and B-scanning, and radiography have been used in a complementary manner for detection of volumetric (cavity and flash) and planar (de bond) defects as the defects are in micron level. Advanced ultrasonic C-scanning did not provide any idea about the defects, whereas B-scanning cross-sectional image showed an exclusive overview of the micron-level defects. A digital x-ray radiography methodology is proposed for quality assessment of the dissimilar welds which provide three-fold increase in signal-to-noise ratio with improved defect detection sensitivity. The present study clearly shows that the weld tool rotational speed and travel speed have a decisive role on the quality of the joints obtained by the friction stir welding process. The suitability of the proposed NDE techniques to evaluate the joint integrity of dissimilar FSW joints is thus established.

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.

Friction stir welding process and material microstructure evolution modeling in 2000 and 5000 series of aluminum alloy

NASA Astrophysics Data System (ADS)

Yalavarthy, Harshavardhan

Interactions between the rotating and advancing pin-shaped tool (terminated at one end with a circular-cylindrical shoulder) with the clamped welding-plates and the associated material and heat transport during a Friction Stir Welding (FSW) process are studied computationally using a fully-coupled thermo-mechanical finite-element analysis. To surmount potential numerical problems associated with extensive mesh distortions/entanglement, an Arbitrary Lagrangian Eulerian (ALE) formulation was used which enabled adaptive re-meshing (to ensure the continuing presence of a high-quality mesh) while allowing full tracking of the material free surfaces. To demonstrate the utility of the present computational approach, the analysis is applied to the cases of same-alloy FSW of two Aluminum-alloy grades: (a) AA5083 (a solid-solution strengthened and strain-hardened/stabilized Al-Mg-Mn alloy); and (b) AA2139 (a precipitation hardened quaternary Al-Cu-Mg-Ag alloy). Both of these alloys are currently being used in military-vehicle hull structural and armor systems. In the case of non-age-hardenable AA5083, the dominant microstructure evolution processes taking place during FSW are extensive plastic deformation and dynamic recrystallization of highly-deformed material subjected to elevated temperatures approaching the melting temperature. To account for the competition between plastic-deformation controlled strengthening and dynamic-recrystallization induced softening phenomena during the FSW process, the original Johnson-Cook strain- and strain-rate hardening and temperature-softening material strength model is modified in the present work using the available recrystallization-kinetics experimental data. In the case of AA2139, in addition to plastic deformation and dynamic recrystallization, precipitates coarsening, over-aging, dissolution and re-precipitation had to be also considered. Limited data available in the open literature pertaining to the kinetics of the aforementioned

Properties of micro-arc oxidation coatings on aluminum alloy at different negative peak current densities

NASA Astrophysics Data System (ADS)

Gu, Xin; Jiang, Bailing; Li, Hongtao; Liu, Cancan; Shao, Lianlian

2018-05-01

Micro-arc oxidation coatings were fabricated on 6061 aluminum alloy using whereby bipolar pulse mode in the case of different negative peak current densities. The phase composition, microstructures and wear properties were studied using x-ray diffraction, scanning electron microscopy and ball-on-disk wear tester, respectively. As results indicate, by virtue of negative peak current density, the oxygen can be expelled by produced hydrogen on anode in the case of negative pulse width and via the opened discharge channel. The results of x-ray diffraction, surface and cross-sectional morphology indicated that the coating was structured compactly taking on less small-diameter micro-pores and defects with negative peak current density of 75 A dm‑2. Additionally, as the results of wear tracks and weight loss bespeak, by virtue of appropriate negative peak current density, coatings resisted the abrasive wear and showed excellent wear resistance.

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.

Effect of TiC addition on fracture toughness of Al6061 alloy

NASA Astrophysics Data System (ADS)

Raviraj, M. S.; Sharanprabhu, C. M.; Mohankumar, G. C.

2018-04-01

Al 6061 matrix was reinforced with different proportions of TiC particles such as 3wt%, 5wt% and 7wt% and the effect on fracture toughness was studied. Al-TiC metal matrix composites were produced by stir casting method to ensure uniform distribution of the TiC particulates in the Al matrix. LEFM (Linear Elastic Fracture Mechanics) has been used to characterize the fracture toughness using various specimen geometries. The compact tension (CT) specimens with straight through notch were machined as per ASTM E399 specifications. All the specimens were machined to have constant a/W=0.5 and B/W was varied from 0.2 to 0.7. A sharp crack initiation was done at the end of notch by fatigue loading using servo-hydraulic controlled testing machine. Load v/s crack mouth opening displacement (CMOD) data was plotted and stress intensity factor, KQ determined. Critical stress intensity factor KIC was obtained by plotting KQ v/s thickness of specimen data. The fracture toughness of the composites varied between 16-19 MPa√m as compared to 23MPa√m for base alloy Al6061. Composites with 3wt% and 7wt% TiC showed better fracture toughness than 5wt% TiC reinforced Al metal matrix composites.

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

Analysis of Particle-Stimulated Nucleation (PSN)-Dominated Recrystallization for Hot-Rolled 7050 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Adam, Khaled F.; Long, Zhengdong; Field, David P.

2017-04-01

In 7xxx series aluminum alloys, the constituent large and small second-phase particles present during deformation process. The fraction and spatial distribution of these second-phase particles significantly influence the recrystallized structure, kinetics, and texture in the subsequent treatment. In the present work, the Monte Carlo Potts model was used to model particle-stimulated nucleation (PSN)-dominated recrystallization and grain growth in high-strength aluminum alloy 7050. The driving force for recrystallization is deformation-induced stored energy, which is also strongly affected by the coarse particle distribution. The actual microstructure and particle distribution of hot-rolled plate were used as an initial point for modeling of recrystallization during the subsequent solution heat treatment. Measurements from bright-field TEM images were performed to enhance qualitative interpretations of the developed microstructure. The influence of texture inhomogeneity has been demonstrated from a theoretical point of view using pole figures. Additionally, in situ annealing measurements in SEM were performed to track the orientational and microstructural changes and to provide experimental support for the recrystallization mechanism of PSN in AA7050.

Fundamental Investigation of Fatigue Crack Growth Retardation in Aluminum Alloys

DTIC Science & Technology

1976-09-01

Fatigue Crack Propagation in 2024 -T3 Aluminum Alloy , " ASTM STP 536, p. 115, 1973. 9. J. Schijve, " Effect of Load Sequences...Hertzberg, " Effect of Multiple Over- loads on Fatigue Crack Propagation in 2024 -T3 Aluminum Alloy , " ASTM STP-536, p. 115, 1973. 9. J. Schijve... Effect of Thickness on Retardation Behavior of 7075 and 2024 Aluminum Alloys .......... 185 vi LIST OF ILLUSTRATIONS FIGURE PAGE 1 SEN

The corrosion protection of 6061-T6 aluminum by a polyurethane-sealed anodized coat

NASA Technical Reports Server (NTRS)

Danford, M. D.

1990-01-01

The corrosion protection of 6061-T6 anodized aluminum afforded by a newly patented polyurethane seal was studied using the ac impedance technique. Values of the average corrosion rates over a 27-day exposure period in 3.5 percent NaCl solutions at pH 5.2 and pH 9.5 compared very favorably for Lockheed-prepared polyurethane-sealed and dichromate-sealed coats of the same thickness. Average corrosion rates for both specimens over the first 7 days of exposure compared well with those for a hard anodized, dichromate-sealed coat, but rose well above those for the hard anodized coat over the entire 27-day period. This is attributed both to the greater thickness of the hard anodized coat, and possibly to its inherently better corrosion protective capability.

Lattice mismatch modeling of aluminum alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shin, Dongwon; Roy, Shibayan; Watkins, Thomas R.

We present a theoretical framework to accurately predict the lattice mismatch between the fcc matrix and precipitates in the multi-component aluminum alloys as a function of temperature and composition. We use a computational thermodynamic approach to model the lattice parameters of the multi-component fcc solid solution and θ'-Al2Cu precipitate phase. Better agreement between the predicted lattice parameters of fcc aluminum in five commercial alloys (206, 319, 356, A356, and A356 + 0.5Cu) and experimental data from the synchrotron X-ray diffraction (SXD) has been obtained when simulating supersaturated rather than equilibrium solid solutions. We use the thermal expansion coefficient of thermodynamicallymore » stable θ-Al2Cu to describe temperature-dependent lattice parameters of meta-stable θ' and to show good agreement with the SXD data. Both coherent and semi-coherent interface mismatches between the fcc aluminum matrix and θ' in Al-Cu alloys are presented as a function of temperature. Our calculation results show that the concentration of solute atoms, particularly Cu, in the matrix greatly affects the lattice mismatch« less

The Inhibition of Aluminum Corrosion in Sulfuric Acid by Poly(1-vinyl-3-alkyl-imidazolium Hexafluorophosphate).

PubMed

Arellanes-Lozada, Paulina; Olivares-Xometl, Octavio; Guzmán-Lucero, Diego; Likhanova, Natalya V; Domínguez-Aguilar, Marco A; Lijanova, Irina V; Arce-Estrada, Elsa

2014-08-07

Compounds of poly(ionic liquid)s (PILs), derived from imidazole with different alkylic chain lengths located in the third position of the imidazolium ring (poly(1-vinyl-3-dodecyl-imidazolium) (PImC 12 ), poly(1-vinyl-3-octylimidazolium) (PImC₈) and poly(1-vinyl-3-butylimidazolium) (PImC₄) hexafluorophosphate) were synthesized. These compounds were tested as corrosion inhibitors on aluminum alloy AA6061 in diluted sulfuric acid (0.1-1 M H₂SO₄) by weight loss tests, polarization resistance measurements and inductively coupled plasma optical emission spectroscopy. Langmuir's isotherms suggested film formation on bare alloy while standard free energy indicated inhibition by a physisorption process. However, compound efficiencies as inhibitors ranked low (PImC 12 > PImC₈ > PImC₄) to reach 61% for PImC 12 in highly diluted acidic solution. Apparently, the high mobility of sulfates favored their adsorption in comparison to PILs. The surface film displayed general corrosion, and pitting occurred as a consequence of PILs' partial inhibition along with a continuous dissolution of defective patchy film on formation. A slight improvement in efficiency was displayed by compounds having high molecular weight and a long alkyl chain, as a consequence of steric hindrance and PIL interactions.

The influence of cladding on fission gas release from irradiated U-Mo monolithic fuel

NASA Astrophysics Data System (ADS)

Burkes, Douglas E.; Casella, Amanda J.; Casella, Andrew M.

2017-04-01

The monolithic uranium-molybdenum (U-Mo) alloy has been proposed as a fuel design capable of converting the world's highest power research reactors from use of high enriched uranium to low enriched uranium. However, a zirconium (Zr) diffusion barrier must be used to eliminate interactions that form between the U-Mo monolith and aluminum alloy 6061 (AA6061) cladding during fabrication and are enhanced during irradiation. One aspect of fuel development and qualification is to demonstrate an appropriate understanding of the extent of fission product release from the fuel under anticipated service environments. An exothermic reaction has previously been observed between the AA6061 cladding and Zr diffusion layer. In this paper, two fuel segments with different irradiation history were subjected to specified thermal profiles under a controlled atmosphere using a thermogravimetric/differential thermal analyzer coupled with a mass spectrometer inside a hot cell. Samples from each segment were tested with cladding and without cladding to investigate the effect, if any, that the exothermic reaction has on fission gas release mechanisms. Measurements revealed there is an instantaneous effect of the cladding/Zr exothermic reaction, but not necessarily a cumulative effect above approximately 973 K (700 °C). The mechanisms responsible for fission gas release events are discussed.

The influence of cladding on fission gas release from irradiated U-Mo monolithic fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burkes, Douglas E.; Casella, Amanda J.; Casella, Andrew M.

2017-04-01

The monolithic uranium-molybdenum (U-Mo) alloy has been proposed as a fuel design capable of converting the world’s highest power research reactors from use of high enriched uranium to low enriched uranium. However, a zirconium (Zr) diffusion barrier must be used to eliminate interactions that form during fabrication and are enhanced during irradiation between the U-Mo monolith and aluminum alloy 6061 (AA6061) cladding. One aspect of fuel development and qualification is to demonstrate appropriate understanding of the extent of fission product release from the fuel under anticipated service environments. An exothermic reaction has previously been observed between the AA6061 cladding andmore » Zr diffusion layer. In this paper, two fuel segments with different irradiation history were subjected to specified thermal profiles under a controlled atmosphere using a thermogravimetric/differential thermal analyzer coupled with a mass spectrometer inside a hot cell. Samples from each segment were tested with cladding and without cladding to investigate the effect, if any, that the exothermic reaction has on fission gas release mechanisms. Measurements revealed there is an instantaneous effect of the cladding/Zr exothermic reaction, but not necessarily a cumulative effect above approximately 973 K (700 oC). The mechanisms responsible for fission gas release events are discussed.« less

Growth kinetics and microstructural evolution during hot isostatic pressing of U-10 wt.% Mo monolithic fuel plate in AA6061 cladding with Zr diffusion barrier

DOE Office of Scientific and Technical Information (OSTI.GOV)

Y. Park; J. Yoo; K. Huang

2014-04-01

Phase constituents and microstructure changes in RERTR fuel plate assemblies as functions of temperature and duration of hot-isostatic pressing (HIP) during fabrication were examined. The HIP process was carried out as functions of temperature (520, 540, 560 and 580 °C for 90 min) and time (45–345 min at 560 °C) to bond 6061 Al-alloy to the Zr diffusion barrier that had been co-rolled with U-10 wt.% Mo (U10Mo) fuel monolith prior to the HIP process. Scanning and transmission electron microscopies were employed to examine the phase constituents, microstructure and layer thickness of interaction products from interdiffusion. At the interface betweenmore » the U10Mo and Zr, following the co-rolling, the UZr2 phase was observed to develop adjacent to Zr, and the a-U phase was found between the UZr2 and U10Mo, while the Mo2Zr was found as precipitates mostly within the a-U phase. The phase constituents and thickness of the interaction layer at the U10Mo-Zr interface remained unchanged regardless of HIP processing variation. Observable growth due to HIP was only observed for the (Al,Si)3Zr phase found at the Zr/AA6061 interface, however, with a large activation energy of 457 ± 28 kJ/mole. Thus, HIP can be carried to improve the adhesion quality of fuel plate without concern for the excessive growth of the interaction layer, particularly at the U10Mo-Zr interface with the a-U, Mo2Zr, and UZr2 phases.« less

Structural Phase Evolution in Ultrasonic-Assisted Friction Stir Welded 2195 Aluminum Alloy Joints

NASA Astrophysics Data System (ADS)

Eliseev, A. A.; Fortuna, S. V.; Kalashnikova, T. A.; Chumaevskii, A. V.; Kolubaev, E. A.

2017-10-01

The authors examined the structural and phase state of fixed joints produced by method of friction stir welding (FSW) and ultrasonic-assisted friction stir welding (UAFSW) from extruded profile of aluminum alloy AA2195. In order to identify the role of ultrasonic application in the course of welding, such characteristics, as volume fraction and average size of secondary particles are compared in the base material and stir zones of FSW and UAFSW joints. By applying the methods of SEM and TEM analysis, researchers established the complex character of phase transitions as a result of ultrasonic application.

Effects of silicon, copper and iron on static and dynamic properties of alloy 206 (aluminum-copper) in semi-solids produced by the SEED process

NASA Astrophysics Data System (ADS)

Lemieux, Alain

wrought alloy AA6061. At present, there is simply no known application for pressure die-cast alloy with 206 (Liquid Die-casting). This is mainly due to the high propensity to hot cracking and limitations facing the part geometry and the subsequent assembly. This study demonstrated that in addition to pieces produced by semi-solid die-casting using large variations in chemical composition, the SEED process allows obtaining spare sound (sound part) and more complex geometry. Moreover, as the semi-solid parts have less porosity, they can also be machined and welded for some applications. The conclusions of this study demonstrate significant progress in identifying the main issues related to the feasibility of die-casting good parts with high performance using the modified 206 alloy combined with SEED process. This work is therefore a baseline work in the development of new Al-Cu alloys for industries of semi-solid and, at the same time, for the expansion of aluminum for high performance applications in the industry. N.B. This thesis is part of a research project developed by the NSERC / Rio Tinto Akan Industrial Research Chair in Metallurgy of Innovative Aluminum Transformation (CIMTAL).

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.

Fume generation rates for stainless steel, nickel and aluminum alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castner, H.R.

1996-12-01

This paper describes a study of the effects of pulsed welding current on fume produced during gas metal arc welding (GMAW) of stainless steel, nickel, and aluminum alloys. This is an extension of earlier studies of mild steel electrode wire. Reduction of welding fume is important because steady current GMAW of stainless steels and nickel alloys may produce fume that exceeds recommended worker exposure limits for some of the fume constituents. Fume generation from aluminum alloy ER5356 was studied because steady current welding with this alloy produces much higher fume generation rates than ER4043 alloy electrode wire. This work showsmore » that pulsed current can reduce GMAW fume generation rates for Er308L, ER310, and ER312 stainless steel, ERNiCr-3 nickel alloy, and ER5356 aluminum-magnesium alloy electrode wires.« less

Fatigue FEM analysis in the case of brazed aluminium alloy 3L59 used in aeronautical industry

NASA Astrophysics Data System (ADS)

Dimitrescu, A.; Amza, Gh; Niţoi, D. F.; Amza, C. Gh; Apostolescu, Z.

2016-08-01

The use, on a larger scale, of brazed aluminum alloys in the aerospace industry led to the need for a detailed study of the assemblies behavior. These are built from 6061 aluminum aloy (3L59) brazed with aluminum aloy A103. Therefore, a finit element simulation (FEM) of durability is necessary, that consists in the observation of gradual deterioration until failure. These studies are required and are previous to the stage of the producing the assembly and test it by traditional methods.

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.

Materials data handbook: Aluminum alloy 7075

NASA Technical Reports Server (NTRS)

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

1972-01-01

A summary of the materials property information on aluminum alloy 7075 is presented. The scope of the information includes physical and mechanical properties of the alloy at cryogenic, ambient, and elevated temperatures. Information on material procurement, metallurgy, corrosion, environmental effects, fabrication, and joining techniques is developed.

Materials data handbook: Aluminum alloy 5456

NASA Technical Reports Server (NTRS)

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

1972-01-01

A summary of the materials property information for aluminum alloy 5456 is presented. The scope of the information includes physical and mechanical property data at cryogenic, ambient, and elevated temperatures. Information on material procurement, metallurgy of the alloy, corrosion, environmental effects, fabrication, and joining techniques is developed.

Oxidation of nickel-aluminum and iron-aluminum alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cathcart, J.V.

1984-01-01

The high-temperature oxidation behavior of several ordered alloys in the Ni-Al and Fe-Al systems is reviewed with special emphasis on Ni/sub 3/Al and NiAl. Ordering influences oxidation through its effect on the activities of the alloy components and by changing the point defect concentration in an alloy. Three categories of Ni-Al alloys are distinguished based on Al content and oxidation behavior. A characteristic feature of the oxidation of high-aluminum Ni-Al and Fe-Al alloys is the formation of voids in the substrate at the oxide-metal interface. The mechanism of void formation and its suppression by minor additions of oxygen-active elements aremore » discussed. A brief description of the effect of pre-oxidation on the reactions of Ni/sub 3/Al-base alloys in SO/sub 2//O/sub 2/ environments is also included.« less

Laser surface alloying on aluminum and its alloys: A review

NASA Astrophysics Data System (ADS)

Chi, Yiming; Gu, Guochao; Yu, Huijun; Chen, Chuanzhong

2018-01-01

Aluminum and its alloys have been widely used in aerospace, automotive and transportation industries owing to their excellent properties such as high specific strength, good ductility and light weight. Surface modification is of crucial importance to the surface properties of aluminum and its alloys since high coefficient of friction, wear characteristics and low hardness have limited their long term performance. Laser surface alloying is one of the most effective methods of producing proper microstructure by means of non-equilibrium solidification which results from rapid heating and cooling. In this paper, the influence of different processing parameters, such as laser power and scanning velocity is discussed. The developments of various material systems including ceramics, metals or alloys, and metal matrix composites (MMCs) are reviewed. The microstructure, hardness, wear properties and other behaviors of laser treated layer are analyzed. Besides, the existing problems during laser surface treatment and the corresponding solutions are elucidated and the future developments are predicted.

Synthesis of aluminum-based scandium-yttrium master alloys

NASA Astrophysics Data System (ADS)

Bazhin, V. Yu.; Kosov, Ya. I.; Lobacheva, O. L.; Dzhevaga, N. V.

2015-07-01

The preparation technology for an Al-2% Sc-0.5% Y master alloy using aluminum-manganese alloys has been developed and tested. The microstructure of the prepared master alloy is studied and the compositions of intermetallics is determined. The efficient technological parameters of the synthesis are determined. It is shown that varying the compositions of starting reagents and alloying additions and optimizing the process conditions (temperature, mixing, etc.) allow us to forecast the manufacturing and operating characteristics of aluminum-based master alloys. Joint additions of scandium and yttrium oxides to a charge favor a substantial decrease in the grain size of the formed intermetallics; this effect appears to the utmost in the case of microallying with yttrium up to 0.5 wt %.

The effect of welding parameters on surface quality of AA6351 aluminium alloy

NASA Astrophysics Data System (ADS)

Yacob, S.; MAli, M. A.; Ahsan, Q.; Ariffin, N.; Ali, R.; Arshad, A.; Wahab, M. I. A.; Ismail, S. A.; Roji, NS M.; Din, W. B. W.; Zakaria, M. H.; Abdullah, A.; Yusof, M. I.; Kamarulzaman, K. Z.; Mahyuddin, A.; Hamzah, M. N.; Roslan, R.

2015-12-01

In the present work, the effects of gas metal arc welding-cold metal transfer (GMAW-CMT) parameters on surface roughness are experimentally assessed. The purpose of this study is to develop a better understanding of the effects of welding speed, material thickness and contact tip to work distance on the surface roughness. Experiments are conducted using single pass gas metal arc welding-cold metal transfer (GMAW-CMT) welding technique to join the material. The material used in this experiment was AA6351 aluminum alloy with the thickness of 5mm and 6mm. A Mahr Marsuft XR 20 machine was used to measure the average roughness (Ra) of AA6351 joints. The main and interaction effect analysis was carried out to identify process parameters that affect the surface roughness. The results show that all the input process parameters affect the surface roughness of AA6351 joints. Additionally, the average roughness (Ra) results also show a decreasing trend with increased of welding speed. It is proven that gas metal arc welding-cold metal transfer (GMAW-CMT)welding process has been successful in term of providing weld joint of good surface quality for AA6351 based on the low value surface roughness condition obtained in this setup. The outcome of this experimental shall be valuable for future fabrication process in order to obtained high good quality weld.

Properties of Free-Machining Aluminum Alloys at Elevated Temperatures

NASA Astrophysics Data System (ADS)

Faltus, Jiří; Karlík, Miroslav; Haušild, Petr

In areas close to the cutting tool the workpieces being dry machined could be heated up to 350°C and they may be impact loaded. Therefore it is of interest to study mechanical properties of corresponding materials at elevated temperatures. Free-machining alloys of Al-Cu and Al-Mg-Si systems containing Pb, Bi and Sn additions (AA2011, AA2111B, AA6262, and AA6023) were subjected to Charpy U notch impact test at the temperatures ranging from 20 to 350°C. The tested alloys show a sharp drop in notch impact strength KU at different temperatures. This drop of KU is caused by liquid metal embrittlement due to the melting of low-melting point dispersed phases which is documented by differential scanning calorimetry. Fracture surfaces of the specimens were observed using a scanning electron microscope. At room temperature, the fractures of all studied alloys exhibited similar ductile dimple fracture micromorphology, at elevated temperatures, numerous secondary intergranular cracks were observed.

Oxidation of nickel-aluminum and iron-aluminum alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cathcart, J.V.

1985-01-01

The high-temperature oxidation behavior of several ordered alloys in the Ni-Al and Fe-Al systems is reviewed with special emphasis on Ni/sub 3/Al and NiAl. Ordering influences oxidation through its effect on the activities of the alloy components and by changing the point defect concentration in an alloy. Three categories of Ni-Al alloys are distinguished based on Al content and oxidation behavior. A characteristic feature of the oxidation of high-aluminum Ni-Al and Fe-Al alloys is the formation of voids in the substrate at the oxidate-metal interface. The mechanism of void formation and its suppression by minor additions of oxygen-active elements ismore » discussed. A brief description of the effect of preoxidation on the reactions of Ni/sub 3/Al-base alloys in SO/sub 2//O/sub 2/ environments is also included. 51 references, 14 figures, 1 table.« less

Influence of tool geometry and processing parameters on welding defects and mechanical properties for friction stir welding of 6061 Aluminium alloy

NASA Astrophysics Data System (ADS)

Daneji, A.; Ali, M.; Pervaiz, S.

2018-04-01

Friction stir welding (FSW) is a form of solid state welding process for joining metals, alloys, and selective composites. Over the years, FSW development has provided an improved way of producing welding joints, and consequently got accepted in numerous industries such as aerospace, automotive, rail and marine etc. In FSW, the base metal properties control the material’s plastic flow under the influence of a rotating tool whereas, the process and tool parameters play a vital role in the quality of weld. In the current investigation, an array of square butt joints of 6061 Aluminum alloy was to be welded under varying FSW process and tool geometry related parameters, after which the resulting weld was evaluated for the corresponding mechanical properties and welding defects. The study incorporates FSW process and tool parameters such as welding speed, pin height and pin thread pitch as input parameters. However, the weld quality related defects and mechanical properties were treated as output parameters. The experimentation paves way to investigate the correlation between the inputs and the outputs. The correlation between inputs and outputs were used as tool to predict the optimized FSW process and tool parameters for a desired weld output of the base metals under investigation. The study also provides reflection on the effect of said parameters on a welding defect such as wormhole.

Chemically activated nanodiamonds for aluminum alloy corrosion protection and monitoring

NASA Astrophysics Data System (ADS)

Hannstein, Inga; Adler, Anne-Katrin; Lapina, Victoria; Osipov, Vladimir; Opitz, Jörg; Schreiber, Jürgen; Meyendorf, Norbert

2009-03-01

In the present study, a smart coating for light metal alloys was developed and investigated. Chemically activated nanodiamonds (CANDiT) were electrophoretically deposited onto anodized aluminum alloy AA2024 substrates in order to increase corrosion resistance, enhance bonding properties and establish a means of corrosion monitoring based on the fluorescence behavior of the particles. In order to create stable aqueous CANDiT dispersions suitable for electrophoretic deposition, mechanical milling had to be implemented under specific chemical conditions. The influence of the CANDiT volume fraction and pH of the dispersion on the electrochemical properties of the coated samples was investigated. Linear voltammetry measurements reveal that the chemical characteristics of the CANDiT dispersion have a distinct influence on the quality of the coating. The fluorescence spectra as well as fluorescence excitation spectra of the samples show that corrosion can be easily detected by optical means. Furthermore, an optimization on the basis of "smart" - algorithms for the data processing of a surface analysis by the laser-speckle-method is presented.

Corrosion of aluminum alloy 2024 by microorganisms isolated from aircraft fuel tanks.

PubMed

McNamara, Christopher J; Perry, Thomas D; Leard, Ryan; Bearce, Ktisten; Dante, James; Mitchell, Ralph

2005-01-01

Microorganisms frequently contaminate jet fuel and cause corrosion of fuel tank metals. In the past, jet fuel contaminants included a diverse group of bacteria and fungi. The most common contaminant was the fungus Hormoconis resinae. However, the jet fuel community has been altered by changes in the composition of the fuel and is now dominated by bacterial contaminants. The purpose of this research was to determine the composition of the microbial community found in fuel tanks containing jet propellant-8 (JP-8) and to determine the potential of this community to cause corrosion of aluminum alloy 2024 (AA2024). Isolates cultured from fuel tanks containing JP-8 were closely related to the genus Bacillus and the fungi Aureobasidium and Penicillium. Biocidal activity of the fuel system icing inhibitor diethylene glycol monomethyl ether is the most likely cause of the prevalence of endospore forming bacteria. Electrochemical impedance spectroscopy and metallographic analysis of AA2024 exposed to the fuel tank environment indicated that the isolates caused corrosion of AA2024. Despite the limited taxonomic diversity of microorganisms recovered from jet fuel, the community has the potential to corrode fuel tanks.

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.

High temperature dynamic modulus and damping of aluminum and titanium matrix composites

NASA Technical Reports Server (NTRS)

Dicarlo, J. A.; Maisel, J. E.

1979-01-01

Dynamic modulus and damping capacity property data were measured from 20 to over 500 C for unidirectional B/Al (1100), B/Al (6061), B/SiC/Al (6061), Al2O3/Al, SiC/Ti-6Al-4V, and SiC/Ti composites. The measurements were made under vacuum by the forced vibration of composite bars at free-free flexural resonance near 2000 Hz and at amplitudes below 0.000001. Whereas little variation was observed in the dynamic moduli of specimens with approximately the same fiber content (50 percent), the damping of B/Al composites was found at all temperatures to be significantly greater than the damping of the Al2O3/Al and SiC/Ti composites. For those few situations where slight deviations from theory were observed, the dynamic data were examined for information concerning microstructural changes induced by composite fabrication and thermal treatment. The 270 C damping peak observed in B/Al (6061) composites after heat treatment above 460 C appears to be the result of a change in the 6061 aluminum alloy microstructure induced by interaction with the boron fibers. The growth characteristics of the damping peak suggest its possible value for monitoring fiber strength degration caused by excess thermal treatment during B/Al (6061) fabrication and use.

Machinability of hypereutectic silicon-aluminum alloys

NASA Astrophysics Data System (ADS)

Tanaka, T.; Akasawa, T.

1999-08-01

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

Transverse-Weld Tensile Properties of a New Al-4Cu-2Si Alloy as Filler Metal

NASA Astrophysics Data System (ADS)

Sampath, K.

2009-12-01

AA2195, an Al-Cu-Li alloy in the T8P4 age-hardened condition, is a candidate aluminum armor for future combat vehicles, as this material offers higher static strength and ballistic protection than current aluminum armor alloys. However, certification of AA2195 alloy for armor applications requires initial qualification based on the ballistic performance of welded panels in the as-welded condition. Currently, combat vehicle manufacturers primarily use gas metal arc welding (GMAW) process to meet their fabrication needs. Unfortunately, a matching GMAW consumable electrode is currently not commercially available to allow effective joining of AA2195 alloy. This initial effort focused on an innovative, low-cost, low-risk approach to identify an alloy composition suitable for effective joining of AA2195 alloy, and evaluated transverse-weld tensile properties of groove butt joints produced using the identified alloy. Selected commercial off-the-shelf (COTS) aluminum alloy filler wires were twisted to form candidate twisted filler rods. Representative test weldments were produced using AA2195 alloy, candidate twisted filler rods and gas tungsten arc welding (GTAW) process. Selected GTA weldments produced using Al-4wt.%Cu-2wt.%Si alloy as filler metal consistently provided transverse-weld tensile properties in excess of 275 MPa (40 ksi) UTS and 8% El (over 25 mm gage length), thereby showing potential for acceptable ballistic performance of as-welded panels. Further developmental work is required to evaluate in detail GMAW consumable wire electrodes based on the Al-Cu-Si system containing 4.2-5.0 wt.% Cu and 1.6-2.0 wt.% Si.

Protection by Thermal and Chemical Activation with Cerium Salts of the Alloy AA2017 in Aqueous Solutions of NaCl

NASA Astrophysics Data System (ADS)

Bethencourt, Manuel; Botana, Francisco Javier; Cano, María José; González-Rovira, Leandro; Marcos, Mariano; Sánchez-Amaya, José María

2012-01-01

A wide variety of anticorrosive treatments for aluminum alloys that can be employed as "green" alternatives to those based on Cr(VI) are currently under development. This article reports a study of the morphological and anticorrosive characteristics of surface layers formed on the Al-Cu alloy AA2017 by immersion treatment in baths of cerium salt, accelerated by increased temperature and the employment of hydrogen peroxide. Scanning electron microscopy (SEM)/X-ray energy dispersive spectroscopy (XEDS) studies of the samples treated have demonstrated the existence of a heterogeneous layer formed by a film of aluminum oxide/hydroxide on the matrix, and a series of dispersed islands of cerium over the cathodic intermetallics. The protective efficacy has been evaluated using electrochemical techniques, linear polarizations (LP) and electrochemical impedance spectroscopy (EIS), and salt spray tests. The results obtained indicate that the layer provided good resistance to corrosion in media with chlorides, and the method gives a considerable reduction of the time required for the immersion treatments.

Biaxial Testing of 2195 Aluminum Lithium Alloy Using Cruciform Specimens

NASA Technical Reports Server (NTRS)

Johnston, W. M.; Pollock, W. D.; Dawicke, D. S.; Wagner, John A. (Technical Monitor)

2002-01-01

A cruciform biaxial test specimen was used to test the effect of biaxial load on the yield of aluminum-lithium alloy 2195. Fifteen cruciform specimens were tested from 2 thicknesses of 2195-T8 plate, 0.45 in. and 1.75 in. These results were compared to the results from uniaxial tensile tests of the same alloy, and cruciform biaxial tests of aluminum alloy 2219-T87.

High Strength and Wear Resistant Aluminum Alloy for High Temperature Applications

NASA Technical Reports Server (NTRS)

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

2002-01-01

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

Measurements and Modeling of Stress in Precipitation-Hardened Aluminum Alloy AA2618 during Gleeble Interrupted Quenching and Constrained Cooling

NASA Astrophysics Data System (ADS)

Chobaut, Nicolas; Carron, Denis; Saelzle, Peter; Drezet, Jean-Marie

2016-11-01

Solutionizing and quenching are the key steps in the fabrication of heat-treatable aluminum parts such as AA2618 compressor impellers for turbochargers as they highly impact the mechanical characteristics of the product. In particular, quenching induces residual stresses that can cause unacceptable distortions during machining and unfavorable stresses in service. Predicting and controlling stress generation during quenching of large AA2618 forgings are therefore of particular interest. Since possible precipitation during quenching may affect the local yield strength of the material and thus impact the level of macroscale residual stresses, consideration of this phenomenon is required. A material model accounting for precipitation in a simple but realistic way is presented. Instead of modeling precipitation that occurs during quenching, the model parameters are identified using a limited number of tensile tests achieved after representative interrupted cooling paths in a Gleeble machine. This material model is presented, calibrated, and validated against constrained coolings in a Gleeble blocked-jaws configuration. Applications of this model are FE computations of stress generation during quenching of large AA2618 forgings for compressor impellers.

Machinability of Al 6061 Deposited with Cold Spray Additive Manufacturing

NASA Astrophysics Data System (ADS)

Aldwell, Barry; Kelly, Elaine; Wall, Ronan; Amaldi, Andrea; O'Donnell, Garret E.; Lupoi, Rocco

2017-10-01

Additive manufacturing techniques such as cold spray are translating from research laboratories into more mainstream high-end production systems. Similar to many additive processes, finishing still depends on removal processes. This research presents the results from investigations into aspects of the machinability of aluminum 6061 tubes manufactured with cold spray. Through the analysis of cutting forces and observations on chip formation and surface morphology, the effect of cutting speed, feed rate, and heat treatment was quantified, for both cold-sprayed and bulk aluminum 6061. High-speed video of chip formation shows changes in chip form for varying material and heat treatment, which is supported by the force data and quantitative imaging of the machined surface. The results shown in this paper demonstrate that parameters involved in cold spray directly impact on machinability and therefore have implications for machining parameters and strategy.

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.

Improvement of Strength and Energy Absorption Properties of Porous Aluminum Alloy with Aligned Unidirectional Pores Using Equal-Channel Angular Extrusion

NASA Astrophysics Data System (ADS)

Yoshida, Tomonori; Muto, Daiki; Tamai, Tomoya; Suzuki, Shinsuke

2018-04-01

Porous aluminum alloy with aligned unidirectional pores was fabricated by dipping A1050 tubes into A6061 semi-solid slurry. The porous aluminum alloy was processed through Equal-channel Angular Extrusion (ECAE) while preventing cracking and maintaining both the pore size and porosity by setting the insert material and loading back pressure. The specific compressive yield strength of the sample aged after 13 passes of ECAE was approximately 2.5 times higher than that of the solid-solutionized sample without ECAE. Both the energy absorption E V and energy absorption efficiency η V after four passes of ECAE were approximately 1.2 times higher than that of the solid-solutionized sample without ECAE. The specific yield strength was improved via work hardening and precipitation following dynamic aging during ECAE. E V was improved by the application of high compressive stress at the beginning of the compression owing to work hardening via ECAE. η V was improved by a steep increase of stress at low compressive strain and by a gradual increase of stress in the range up to 50 pct of compressive strain. The gradual increase of stress was caused by continuous shear fracture in the metallic part, which was due to the high dislocation density and existence of unidirectional pores parallel to the compressive direction in the structure.

Improvement of Strength and Energy Absorption Properties of Porous Aluminum Alloy with Aligned Unidirectional Pores Using Equal-Channel Angular Extrusion

NASA Astrophysics Data System (ADS)

Yoshida, Tomonori; Muto, Daiki; Tamai, Tomoya; Suzuki, Shinsuke

2018-06-01

Porous aluminum alloy with aligned unidirectional pores was fabricated by dipping A1050 tubes into A6061 semi-solid slurry. The porous aluminum alloy was processed through Equal-channel Angular Extrusion (ECAE) while preventing cracking and maintaining both the pore size and porosity by setting the insert material and loading back pressure. The specific compressive yield strength of the sample aged after 13 passes of ECAE was approximately 2.5 times higher than that of the solid-solutionized sample without ECAE. Both the energy absorption E V and energy absorption efficiency η V after four passes of ECAE were approximately 1.2 times higher than that of the solid-solutionized sample without ECAE. The specific yield strength was improved via work hardening and precipitation following dynamic aging during ECAE. E V was improved by the application of high compressive stress at the beginning of the compression owing to work hardening via ECAE. η V was improved by a steep increase of stress at low compressive strain and by a gradual increase of stress in the range up to 50 pct of compressive strain. The gradual increase of stress was caused by continuous shear fracture in the metallic part, which was due to the high dislocation density and existence of unidirectional pores parallel to the compressive direction in the structure.

Investigations of Effect of Rotary EDM Electrode on Machining Performance of Al6061 Alloy

NASA Astrophysics Data System (ADS)

Robinson Smart, D. S.; Jenish Smart, Joses; Periasamy, C.; Ratna Kumar, P. S. Samuel

2018-04-01

Electric Discharge Machining is an essential process which is being used for machining desired shape using electrical discharges which creates sparks. There will be electrodes subjected to electric voltage and which are separated by a dielectric liquid. Removing of material will be due to the continuous and rapid current discharges between two electrodes.. The spark is very carefully controlled and localized so that it only affects the surface of the material. Usually in order to prevent the defects which are arising due to the conventional machining, the Electric Discharge Machining (EDM) machining is preferred. Also intricate and complicated shapes can be machined effectively by use of Electric Discharge Machining (EDM). The EDM process usually does not affect the heat treat below the surface. This research work focus on the design and fabrication of rotary EDM tool for machining Al6061alloy and investigation of effect of rotary tool on surface finish, material removal rate and tool wear rate. Also the effect of machining parameters of EDM such as pulse on & off time, current on material Removal Rate (MRR), Surface Roughness (SR) and Electrode wear rate (EWR) have studied. Al6061 alloy can be used for marine and offshore applications by reinforcing some other elements. The investigations have revealed that MRR (material removal rate), surface roughness (Ra) have been improved with the reduction in the tool wear rate (TWR) when the tool is rotating instead of stationary. It was clear that as rotary speed of the tool is increasing the material removal rate is increasing with the reduction of surface finish and tool wear rate.

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.

Carbon Nanotube-Reinforced Aluminum Matrix Composites Produced by High-Energy Ball Milling

NASA Astrophysics Data System (ADS)

Travessa, Dilermando N.; da Rocha, Geovana V. B.; Cardoso, Kátia R.; Lieblich, Marcela

2017-05-01

Although multiwall carbon nanotubes (MWCNT) are promising materials to strengthen lightweight aluminum matrix composites, their dispersion into the metallic matrix is challenge. In the present work, MWCNT were dispersed into age-hardenable AA6061 aluminum alloy by high-energy ball milling and the blend was subsequently hot-extruded. The composite bars obtained were heat-treated by solution heat treatment at 520 °C and artificially aged at 177 °C for 8 h, in order to reach the T6 temper. Special attention was given to the integrity of the MWCNT along the entire composite production. The microstructure of the obtained bars was evaluated by optical and scanning electron microscopy, and the mechanical properties were evaluated by Vickers microhardness tests. Raman spectroscopy, x-ray diffraction and transmission electron microscopy were employed to evaluate the structural integrity of MWCNT. It was found that milling time is critical to reach a proper dispersion of the reinforcing phase. The composite hardness increased up to 67% with the dispersion of 2% in weight of MWCNT, when comparing with un-reinforced bars produced by similar route. However, age hardening was not observed in composite bars after heat treatment. It was also found that MWCNT continuously degraded along the process, being partially converted into Al4C3 in the final composite.

Warm Temperature Deformation Behavior and Processing Maps of 5182 and 7075 Aluminum Alloy Sheets with Fine Grains

NASA Astrophysics Data System (ADS)

Jang, D. H.; Kim, W. J.

2018-05-01

The tensile deformation behavior and processing maps of commercial 5182 and 7075 aluminum alloy sheets with similarly fine grain sizes (about 8 μm) were examined and compared over the temperature range of 423-723 K. The 5182 aluminum alloy with equiaxed grains exhibited larger strain rate sensitivity exponent ( m) values than the 7075 aluminum alloy with elongated grains under most of the testing conditions. The fracture strain behaviors of the two alloys as a function of strain rate and temperature followed the trend in their m values. In the processing maps, the power dissipation parameter values of the 5182 aluminum alloy were larger than those of the 7075 aluminum alloy and the instability domains of the 5182 aluminum alloy were smaller compared to that of the 7075 aluminum alloy, implying that the 5182 aluminum alloy had a better hot workability than the 7075 aluminum alloy.

Effect of Interfacial Reaction on the Mechanical Performance of Steel to Aluminum Dissimilar Ultrasonic Spot Welds

NASA Astrophysics Data System (ADS)

Xu, Lei; Wang, Li; Chen, Ying-Chun; Robson, Joe D.; Prangnell, Philip B.

2016-01-01

The early stages of formation of intermetallic compounds (IMC) have been investigated in dissimilar aluminum to steel welds, manufactured by high power (2.5 kW) ultrasonic spot welding (USW). To better understand the influence of alloy composition, welds were produced between a low-carbon steel (DC04) and two different aluminum alloys (6111 and 7055). The joint strengths were measured in lap shear tests and the formation and growth behavior of IMCs at the weld interface were characterized by electron microscopy, for welding times from 0.2 to 2.4 seconds. With the material combinations studied, the η (Fe2Al5) intermetallic phase was found to form first, very rapidly in the initial stage of welding, with a discontinuous island morphology. Continuous layers of η and then θ (FeAl3) phase were subsequently seen to develop on extending the welding time to greater than 0.7 second. The IMC layer formed in the DC04-AA7055 combination grew thicker than for the DC04-AA6111 welds, despite both weld sets having near identical thermal histories. Zinc was also found to be dissolved in the IMC phases when welding with the AA7055 alloy. After post-weld aging of the aluminum alloy, fracture in the lap shear tests always occurred along the joint interface; however, the DC04-AA6111 welds had higher fracture energy than the DC04-AA7055 combination.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harumoto, Takashi; Tamura, Yohei; Ishiguro, Takashi, E-mail: ishiguro@rs.noda.tus.ac.jp

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.

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.

Study of Plastic Deformation in Binary Aluminum Alloys by Internal-Friction Methods

NASA Technical Reports Server (NTRS)

Olson, E. C.; Maringer, R. E.; Marsh, L. L.; Manning, G. K.

1959-01-01

The damping capacity of several aluminum-copper alloys has been investigated during tensile elongation. This damping is shown to depend on strain rate, strain, temperature, alloy content, and heat treatment. A tentative hypothesis, based on the acceleration of solute atom diffusion by deformation-produced vacancies, is proposed to account for the observed behavior. Internal-friction maxima are observed in deformed aluminum and aluminum-copper alloys at -70 deg and -50 deg C. The peaks appear to be relatively insensitive to frequency and alloy content, but they disappear after annealing at temperatures nearing the recrystallization temperature.

Etching Behavior of Aluminum Alloy Extrusions

NASA Astrophysics Data System (ADS)

Zhu, Hanliang

2014-11-01

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

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.

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.

The Inhibition of Aluminum Corrosion in Sulfuric Acid by Poly(1-vinyl-3-alkyl-imidazolium Hexafluorophosphate)

PubMed Central

Arellanes-Lozada, Paulina; Olivares-Xometl, Octavio; Guzmán-Lucero, Diego; Likhanova, Natalya V.; Domínguez-Aguilar, Marco A.; Lijanova, Irina V.; Arce-Estrada, Elsa

2014-01-01

Compounds of poly(ionic liquid)s (PILs), derived from imidazole with different alkylic chain lengths located in the third position of the imidazolium ring (poly(1-vinyl-3-dodecyl-imidazolium) (PImC12), poly(1-vinyl-3-octylimidazolium) (PImC8) and poly(1-vinyl-3-butylimidazolium) (PImC4) hexafluorophosphate) were synthesized. These compounds were tested as corrosion inhibitors on aluminum alloy AA6061 in diluted sulfuric acid (0.1–1 M H2SO4) by weight loss tests, polarization resistance measurements and inductively coupled plasma optical emission spectroscopy. Langmuir’s isotherms suggested film formation on bare alloy while standard free energy indicated inhibition by a physisorption process. However, compound efficiencies as inhibitors ranked low (PImC12 > PImC8 > PImC4) to reach 61% for PImC12 in highly diluted acidic solution. Apparently, the high mobility of sulfates favored their adsorption in comparison to PILs. The surface film displayed general corrosion, and pitting occurred as a consequence of PILs’ partial inhibition along with a continuous dissolution of defective patchy film on formation. A slight improvement in efficiency was displayed by compounds having high molecular weight and a long alkyl chain, as a consequence of steric hindrance and PIL interactions. PMID:28788156

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.

Effect of Thermomechanical Treatment on the Environmentally Induced Cracking Behavior of AA7075 Alloy

NASA Astrophysics Data System (ADS)

Ghosh, Rahul; Venugopal, A.; Sankaravelayudham, P.; Panda, Rajiv; Sharma, S. C.; George, Koshy M.; Raja, V. S.

2015-02-01

The influence of thermomechanical treatment on the stress corrosion cracking behavior of AA7075 aluminum alloy forgings was examined in 3.5% NaCl solution by varying the extent of thermomechanical working imparted to each of the conditions. The results show that inadequate working during billet processing resulted in inferior corrosion and mechanical properties. However, more working with intermediate pre-heating stages also led to precipitation of coarse particles resulting in lowering of mechanical properties marginally and a significant reduction in the general/pitting corrosion resistance. The results obtained in the present study indicate that optimum working with controlled pre-heating levels is needed during forging to achieve the desired properties. It is also demonstrated that AA7075 in the over aged condition does not show any environmental cracking susceptibility in spite of the microstructural variations in terms of size and volume fraction of the precipitates. However, the above microstructural variations definitely affected the pitting corrosion and mechanical properties significantly and hence a strict control over the working and pre-heating stages during billet processing is suggested.

Erosion of aluminum 6061-T6 under cavitation attack in mineral oil and water

NASA Technical Reports Server (NTRS)

Rao, B. C. S.; Buckley, D. H.

1985-01-01

Studies of the erosion of aluminum 6061-T6 under cavitation attack in distilled water, ordinary tap water and a viscous mineral oil are presented. The mean depth of penetration for the mineral oil was about 40 percent of that for water at the end of a 40 min test. The mean depth of penetration and its rate did not differ significantly for distilled and tap water. The mean depth of penetration rate for both distilled and tap water increased to a maximum and then decreased with test duration, while that for mineral oil had a maximum during the initial period. The ratio h/2a of the pit depth h to the pit diameter 2a varied from 0.04 to 0.13 in water and from 0.06 to 0.20 in mineral oil. Scanning electron microscopy indicates that the pits are initially formed over the grain boundaries and precipitates while the surface grains are deformed under cavitation attack.

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."

Violent oxidation of lithium-containing aluminum alloys in liquid oxygen

NASA Astrophysics Data System (ADS)

Dalins, Ilmars; Karimi, Majid; Ila, Daryush

1991-06-01

A strong exothermic and quite well known thermite reaction involving aluminum, oxygen and transition metals (Fe, Cr, Ni, etc.) has apparently been initiated during impact testing of Alcoa aluminum alloy #2090 in liquid oxygen at NASA-MSFC. In some instances, this reaction, essentially an oxidation process, has been so intense that the Inconel 718 cup containing the aluminum alloy disk and associated impacter has melted raising certain safety concerns in the use of this alloy. Reaction products as well as the test specimen surfaces have been studied with surface science techniques like XPS/ESCA, SIMS and AES. Typically, in order to initiate the thermite reaction a temperature of approximately 1000°C is necessary. The mechanism responsible for this oxidation is of great interest. The analysis of the reaction products together with a theoretical analysis, including digital modeling has been pursued. There is strong evidence that the large relaxation energy of the aluminum oxide coating, formed during the aluminum alloy cleaning process, is causing a highly localized energy release during fracture or lattice deformation which is enhancing the oxidation process to a runaway condition. The presence of alkali atoms (Li) enhances the likelihood and intensity of the oxidation reaction. The details of the surface studies will be discussed.

Effect of rotation speed and welding speed on Friction Stir Welding of AA1100 Aluminium alloy

NASA Astrophysics Data System (ADS)

Raja, P.; Bojanampati, S.; Karthikeyan, R.; Ganithi, R.

2018-04-01

Aluminum AA1100 is the most widely used grade of Aluminium due to its excellent corrosion resistance, high ductility and reflective finish, the selected material was welded with Friction Stir Welding (FSW) process on a CNC machine, using a combination of different tool rotation speed (1500 rpm, 2500 rpm, 3500 rpm) and welding speed (10 mm/min, 30 mm/min, 50 mm/min) as welding parameters. The effect of FSW using this welding parameter was studied by measuring the ultimate tensile strength of the welded joints. A high-speed steel tool was prepared for welding the Aluminium AA1100 alloy having an 8mm shoulder diameter and pin dimension of 4mm diameter and 2.8 mm length. The welded joints were tested using the universal testing machine. It was found that Ultimate Tensile Strength of FSW specimen was highest with a value of 98.08 MPa when the weld was performed at rotation speed of 1500 RPM and welding speed of 50 mm/min.

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.

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.

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.

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.

Adhesive material transfer in the erosion of an aluminum alloy

NASA Technical Reports Server (NTRS)

Salik, J.; Brainard, W. A.

1979-01-01

In order to study the basic mechanisms of erosion, hardened steel balls were shot into annealed 6061 Al alloy targets at velocity of up to 150 m/sec. The projectiles were collected and examined by a scanning electron microscope combined with energy-dispersive X-ray analyzer and it was found that target material in substantial amounts is adhesively transferred to the projectile. The transferred material forms on the projectile surface a layer the thickness of which increases with increases in impact velocity.

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.

Comparative study on Ti/Zr/V and chromate conversion treated aluminum alloys: Anti-corrosion performance and epoxy coating adhesion properties

NASA Astrophysics Data System (ADS)

Zhu, Wen; Li, Wenfang; Mu, Songlin; Fu, Nianqing; Liao, Zhongmiao

2017-05-01

In this study, a Ti/Zr/V conversion coating (TZVCC) was deposited on the surface of aluminum alloy 6063 (AA6063) as an alternative of the chromate conversion coating (CCC). Both the TZVCC treated AA6063 (TZVCC/AA6063) and CCC treated AA6063 (CCC/AA6063) were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) and contact angle measuring device. The anti-corrosion performance of the TZVCC/AA6063 and CCC/AA6063 was evaluated by electrochemical measurements and neutral salt spray tests. It showed that both the surface roughness and surface free energy of the AA6063 were significantly increased after TZVCC treatment. The anti-corrosion performance of TZVCC/AA6063 was superior to that of CCC/AA6063. In addition, the effects of the TZVCC and CCC on the adhesion properties and anti-corrosion performance of epoxy coating applied on samples were examined by pull-off tests and electrochemical impedance spectroscopy (EIS). The dry, wet and recovery adhesive strengths of the epoxy coating on TZVCC treated samples (epoxy coated TZVCC/AA6063) were very close to those of epoxy coating on CCC treated ones (epoxy coated CCC/AA6063). The epoxy coated TZVCC/AA6063 showed better corrosion resistance than the epoxy coated CCC/AA6063 and epoxy coated AA6063.

Stress-Corrosion Cracking in High Strength Steels and in Titanium and Aluminum Alloys

DTIC Science & Technology

1972-01-01

EFFECTS 01: STRESS) 155 Table 2. Mechanical, Fracture, and Stress Corrosion Properties for Plates of Several Aluminum Alloys --Continued 4f’l14...One of the most effective SCC preventives for high strength aluminum alloys is surface working by shot peening, particularl) when used in combination...Aluminaut uses aluminum alloy anodes to supplement the protection of the pressure hull offered by several layers of polyurethane coating 175). 100 A

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

NASA Technical Reports Server (NTRS)

Millan, P. P., Jr.

1982-01-01

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

Acceptable aluminum additions for minimal environmental effect in iron-aluminum alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sikka, V.K.; Viswanathan, S.; Vyas, S.

A systematic study of iron-aluminum alloys has shown that Fe-16 at. % Al alloys are not very sensitive to environmental embrittlement. The Fe-22 and -28 at. % Al alloys are sensitive to environmental embrittlement, and the effect can be reduced by the addition of chromium and through the control of grain size by additions of zirconium and carbon. The Fe-16 at. % Al binary, and alloys based on it, yielded over 20% room-temperature (RT) elongation even after high-temperature annealing treatments at 1100[degree]C. The best values for the Fe-22 and -28 at. % Al-base alloys after similar annealing treatments were 5more » and 10%, respectively. A multicomponent alloy, FAP, based on Fe- 16 at. % Al was designed, which gave an RT ductility of over 25%.« less

Acceptable aluminum additions for minimal environmental effect in iron-aluminum alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sikka, V.K.; Viswanathan, S.; Vyas, S.

A systematic study of iron-aluminum alloys has shown that Fe-16 at. % Al alloys are not very sensitive to environmental embrittlement. The Fe-22 and -28 at. % Al alloys are sensitive to environmental embrittlement, and the effect can be reduced by the addition of chromium and through the control of grain size by additions of zirconium and carbon. The Fe-16 at. % Al binary, and alloys based on it, yielded over 20% room-temperature (RT) elongation even after high-temperature annealing treatments at 1100{degree}C. The best values for the Fe-22 and -28 at. % Al-base alloys after similar annealing treatments were 5more » and 10%, respectively. A multicomponent alloy, FAP, based on Fe- 16 at. % Al was designed, which gave an RT ductility of over 25%.« less

First-principles surface interaction studies of aluminum-copper and aluminum-copper-magnesium secondary phases in aluminum alloys

NASA Astrophysics Data System (ADS)

da Silva, Thiago H.; Nelson, Eric B.; Williamson, Izaak; Efaw, Corey M.; Sapper, Erik; Hurley, Michael F.; Li, Lan

2018-05-01

First-principles density functional theory-based calculations were performed to study θ-phase Al2Cu, S-phase Al2CuMg surface stability, as well as their interactions with water molecules and chloride (Cl-) ions. These secondary phases are commonly found in aluminum-based alloys and are initiation points for localized corrosion. Density functional theory (DFT)-based simulations provide insight into the origins of localized (pitting) corrosion processes of aluminum-based alloys. For both phases studied, Cl- ions cause atomic distortions on the surface layers. The nature of the distortions could be a factor to weaken the interlayer bonds in the Al2Cu and Al2CuMg secondary phases, facilitating the corrosion process. Electronic structure calculations revealed not only electron charge transfer from Cl- ions to alloy surface but also electron sharing, suggesting ionic and covalent bonding features, respectively. The S-phase Al2CuMg structure has a more active surface than the θ-phase Al2Cu. We also found a higher tendency of formation of new species, such as Al3+, Al(OH)2+, HCl, AlCl2+, Al(OH)Cl+, and Cl2 on the S-phase Al2CuMg surface. Surface chemical reactions and resultant species present contribute to establishment of local surface chemistry that influences the corrosion behavior of aluminum alloys.

The Delayed Fracture of Aluminum Alloys.

DTIC Science & Technology

1981-01-01

Cracking of a Maraging Steel ," Corrosion NACE, 1971, vol. 27, no. 10, pp. 429-433. 42. H.R. Smith and D.E. Piper: "Stress- Corrosion Testing with Pre...Sivaramakrishman, and R. Kumar: "Influence of Processing Variables on the Stress Corrosion Characteristics of Weldable Al-Zn-Mg Alloys," Light Met. Age , 1979...if necessary and Identify by block number) aluminum alloys, stress- corrosion cracking, oxide film, Auger electron spectroscopy, Auger depth profiling

Effect of Temper Condition on the Corrosion and Fatigue Performance of AA2219 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Ghosh, Rahul; Venugopal, A.; Rao, G. Sudarshan; Ramesh Narayanan, P.; Pant, Bhanu; Cherian, Roy M.

2018-02-01

The effect of temper condition and corrosion on the fatigue behavior of alloy AA2219 has been investigated in different temper conditions (T87 and T851). Corrosion testing was performed by exposing the tensile specimens to 3.5% NaCl solution for different time periods, and the corrosion damage was quantified using a 3D profilometer. The exposure-tested specimens were subjected for fatigue testing at different stress levels, and the reduction in fatigue life was measured along with detailed fracture morphology variations. The results indicated that the alloy in both tempers suffers localized corrosion damage and the measured corrosion depth was 120 and 1200 µm, respectively, for T87 and T851 conditions. The loss in fatigue strength was found to be high for T851 (67%) when compared to that of T87 temper condition (58%) for a pre-corrosion time of 15 days. In both cases, fatigue crack initiation is associated with corrosion pits, which act as stress raisers. However, the crack propagation was predominantly transgranular for T87 and a mixed transgranular and intergranular fracture in the case of T851 temper condition. This was shown to be due to the heterogeneous microstructure due to the thermomechanical working and the delay in quench time imposed on the alloy forging in T851 temper condition. The findings in this paper present useful information for the selection of appropriate heat treatment condition to facilitate control of the corrosion behavior which is of great significance for their fatigue performance.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bochkareva, Anna, E-mail: avb@ispms.tsc.ru; Lunev, Aleksey, E-mail: agl@ispms.tsc.ru; National Research Tomsk Polytechnic University, Tomsk, 634050

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 formore » 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.« less

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.

Statistical and Graphical Assessment of Circumferential and Radial Hardness Variation of AISI 4140, AISI 1020 and AA 6082 Aluminum Alloy

PubMed Central

Al-Khalid, Hamad; Alaskari, Ayman; Oraby, Samy

2011-01-01

Hardness homogeneity of the commonly used structural ferrous and nonferrous engineering materials is of vital importance in the design stage, therefore, reliable information regarding material properties homogeneity should be validated and any deviation should be addressed. In the current study the hardness variation, over wide spectrum radial locations of some ferrous and nonferrous structural engineering materials, was investigated. Measurements were performed over both faces (cross-section) of each stock bar according to a pre-specified stratified design, ensuring the coverage of the entire area both in radial and circumferential directions. Additionally the credibility of the apparatus and measuring procedures were examined through a statistically based calibration process of the hardness reference block. Statistical and response surface graphical analysis are used to examine the nature, adequacy and significance of the measured hardness values. Calibration of the apparatus reference block proved the reliability of the measuring system, where no strong evidence was found against the stochastic nature of hardness measures over the various stratified locations. Also, outlier elimination procedures were proved to be beneficial only at fewer measured points. Hardness measurements showed a dispersion domain that is within the acceptable confidence interval. For AISI 4140 and AISI 1020 steels, hardness is found to have a slight decrease trend as the diameter is reduced, while an opposite behavior is observed for AA 6082 aluminum alloy. However, no definite significant behavior was noticed regarding the effect of the sector sequence (circumferential direction). PMID:28817030

Statistical and Graphical Assessment of Circumferential and Radial Hardness Variation of AISI 4140, AISI 1020 and AA 6082 Aluminum Alloy.

PubMed

Al-Khalid, Hamad; Alaskari, Ayman; Oraby, Samy

2011-12-23

Hardness homogeneity of the commonly used structural ferrous and nonferrous engineering materials is of vital importance in the design stage, therefore, reliable information regarding material properties homogeneity should be validated and any deviation should be addressed. In the current study the hardness variation, over wide spectrum radial locations of some ferrous and nonferrous structural engineering materials, was investigated. Measurements were performed over both faces (cross-section) of each stock bar according to a pre-specified stratified design, ensuring the coverage of the entire area both in radial and circumferential directions. Additionally the credibility of the apparatus and measuring procedures were examined through a statistically based calibration process of the hardness reference block. Statistical and response surface graphical analysis are used to examine the nature, adequacy and significance of the measured hardness values. Calibration of the apparatus reference block proved the reliability of the measuring system, where no strong evidence was found against the stochastic nature of hardness measures over the various stratified locations. Also, outlier elimination procedures were proved to be beneficial only at fewer measured points. Hardness measurements showed a dispersion domain that is within the acceptable confidence interval. For AISI 4140 and AISI 1020 steels, hardness is found to have a slight decrease trend as the diameter is reduced, while an opposite behavior is observed for AA 6082 aluminum alloy. However, no definite significant behavior was noticed regarding the effect of the sector sequence (circumferential direction).

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

NASA-UVA Light Aerospace Alloy and Structures Technology program (LA2ST)

NASA Technical Reports Server (NTRS)

Starke, Edgar A., Jr.; Gangloff, Richard P.; Herakovich, Carl T.; Scully, John R.; Shiflet, Gary J.; Stoner, Glenn E.; Wert, John A.

1995-01-01

The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites, and thermal gradient structures in collaboration with NASA-Langley researchers. The general aim is to produce relevant data and basic understanding of material mechanical response, environment/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and a pool of educated students for aerospace technologies. Specific technical objectives are presented for each of the following research projects: time-temperature dependent fracture in advanced wrought ingot metallurgy, and spray deposited aluminum alloys; cryogenic temperature effects on the deformation and fracture of Al-Li-Cu-In alloys; effects of aging and temperature on the ductile fracture of AA2095 and AA2195; mechanisms of localized corrosion in alloys 2090 and 2095; hydrogen interactions in aluminum-lithium alloys 2090 and selected model alloys; mechanisms of deformation and fracture in high strength titanium alloys (effects of temperature and hydrogen and effects of temperature and microstructure); evaluations of wide-panel aluminum alloy extrusions; Al-Si-Ge alloy development; effects of texture and precipitates on mechanical property anisotropy of Al-Cu-Mg-X alloys; damage evolution in polymeric composites; and environmental effects in fatigue life prediction - modeling crack propagation in light aerospace alloys.

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.

Reinforcement with alumina particles at the interface region of AA6101-T6 and AA1350 alloys during friction stir welding

NASA Astrophysics Data System (ADS)

Ashok Kumar, R.; Thansekhar, M. R.

2018-04-01

This paper deals the combinational effect of friction stir welding and friction stir processing on dissimilar AA6101-T6 and AA1350 aluminium alloys. For that, alumina particles are reinforced at interface region of AA6101-T6 and AA1350 aluminium alloys. Friction Stir Welding and Friction Stir Processing are done simultaneously for various sizes of groove. To analyze the welding quality and surface modifications, mechanical, wear and microstructural tests are carried out. Among these, smallest groove of 0.5 mm width and 1 mm depth reveals highest tensile and bending strengths and largest groove of 2 mm width and 3 mm depth gives maximum hardness and wear resistance. Taguchi technique shows that groove width is most influencing parameter. Developed second order models with interaction predict the responses with minimum error.

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.

Recrystallization and Grain Growth Kinetics in Binary Alpha Titanium-Aluminum Alloys

NASA Astrophysics Data System (ADS)

Trump, Anna Marie

Titanium alloys are used in a variety of important naval and aerospace applications and often undergo thermomechanical processing which leads to recrystallization and grain growth. Both of these processes have a significant impact on the mechanical properties of the material. Therefore, understanding the kinetics of these processes is crucial to being able to predict the final properties. Three alloys are studied with varying concentrations of aluminum which allows for the direct quantification of the effect of aluminum content on the kinetics of recrystallization and grain growth. Aluminum is the most common alpha stabilizing alloying element used in titanium alloys, however the effect of aluminum on these processes has not been previously studied. This work is also part of a larger Integrated Computational Materials Engineering (ICME) effort whose goal is to combine both computational and experimental efforts to develop computationally efficient models that predict materials microstructure and properties based on processing history. The static recrystallization kinetics are measured using an electron backscatter diffraction (EBSD) technique and a significant retardation in the kinetics is observed with increasing aluminum concentration. An analytical model is then used to capture these results and is able to successfully predict the effect of solute concentration on the time to 50% recrystallization. The model reveals that this solute effect is due to a combination of a decrease in grain boundary mobility and a decrease in driving force with increasing aluminum concentration. The effect of microstructural inhomogeneities is also experimentally quantified and the results are validated with a phase field model for recrystallization. These microstructural inhomogeneities explain the experimentally measured Avrami exponent, which is lower than the theoretical value calculated by the JMAK model. Similar to the effect seen in recrystallization, the addition of aluminum

Residual stress analysis on AA6061+22% Al2O3p simple shape demonstrators of a wheel hub

NASA Astrophysics Data System (ADS)

Giuliani, Alessandra; Albertini, Gianni; Fiori, Fabrizio; Girardin, Emmanuelle

2004-07-01

The effects of thermal treatments in a component for automotive industry are considered: the induced residual stresses in wheel hubs were investigated. Measurements have been carried out on two identical simple shape demonstrators made of AA6061+22% Al2O3p in order to evaluate the stress conditions after forging and T6 treatment and without taking into account the final design of the wheel hub. One sample was analysed in as-forged conditions while the second after forging and T6 treatment (560°C for 2h, 20°C water quenching, artificial aging at 177°C for 10h). Particular attention was given to the stresses in the radial and hoop directions, as the main consequences of the in-service fatigue are expected to be related to stresses along these two directions.

Technology of welding aluminum alloys-II

NASA Technical Reports Server (NTRS)

1978-01-01

Step-by-step procedures were developed for high integrity manual and machine welding of aluminum alloys. Detailed instructions are given for each step with tables and graphs to specify materials and dimensions. Throughout work sequence, processing procedure designates manufacturing verification points and inspection points.

Experimental Study on Dissimilar Friction Stir welding of Aluminium Alloys (5083-H111 and 6082-T6) to investigate the mechanical properties

NASA Astrophysics Data System (ADS)

Kumar, H. M. Anil; Venkata Ramana, V.; Pawar, Mayur

2018-03-01

Friction stir welding is an innovative technology in the joining realm of metals and alloys. This technique is highly economical and suitable especially for non ferrous alloys compared to ferrous alloys. It finds many applications in various fields of aeronautics, automobile, ship building industries etc. The paper presents the comparative results of mechanical properties such as tensile strength, microstructure, macro structure and hardness on the similar and dissimilar aluminum alloys AA5083-H111 and AA6082-T6 under certain selected variables - constant tool rotational speed, its tilt angle, welding speed using friction stir welding process. It is observed from the experimental results that joint efficiency of dissimilar aluminium alloys is higher than the similar aluminum alloys.

Stress-corrosion characteristics of aluminum casting alloy M-45

NASA Technical Reports Server (NTRS)

Lovoy, C. V.

1968-01-01

Evaluation of the stress-corrosion characteristics of aluminum alloy M-45 shows that the most favorable artificial aging cycle for this alloy, with regard to optimum strength and stress-corrosion resistance, appears to be 400 degrees F for 12 hours.

Microstructural Characterization of Friction Stir Welded Aluminum-Steel Joints

NASA Astrophysics Data System (ADS)

Patterson, Erin E.; Hovanski, Yuri; Field, David P.

2016-06-01

This work focuses on the microstructural characterization of aluminum to steel friction stir welded joints. Lap weld configuration coupled with scribe technology used for the weld tool have produced joints of adequate quality, despite the significant differences in hardness and melting temperatures of the alloys. Common to friction stir processes, especially those of dissimilar alloys, are microstructural gradients including grain size, crystallographic texture, and precipitation of intermetallic compounds. Because of the significant influence that intermetallic compound formation has on mechanical and ballistic behavior, the characterization of the specific intermetallic phases and the degree to which they are formed in the weld microstructure is critical to predicting weld performance. This study used electron backscatter diffraction, energy dispersive spectroscopy, scanning electron microscopy, and Vickers micro-hardness indentation to explore and characterize the microstructures of lap friction stir welds between an applique 6061-T6 aluminum armor plate alloy and a RHA homogeneous armor plate steel alloy. Macroscopic defects such as micro-cracks were observed in the cross-sectional samples, and binary intermetallic compound layers were found to exist at the aluminum-steel interfaces of the steel particles stirred into the aluminum weld matrix and across the interfaces of the weld joints. Energy dispersive spectroscopy chemical analysis identified the intermetallic layer as monoclinic Al3Fe. Dramatic decreases in grain size in the thermo-mechanically affected zones and weld zones that evidenced grain refinement through plastic deformation and recrystallization. Crystallographic grain orientation and texture were examined using electron backscatter diffraction. Striated regions in the orientations of the aluminum alloy were determined to be the result of the severe deformation induced by the complex weld tool geometry. Many of the textures observed in the weld

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.

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

NASA Astrophysics Data System (ADS)

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

2014-01-01

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

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.

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.

Anti-icing/frosting and self-cleaning performance of superhydrophobic aluminum alloys

NASA Astrophysics Data System (ADS)

Feng, Libang; Yan, Zhongna; Shi, Xueting; Sultonzoda, Firdavs

2018-02-01

Ice formation and frost deposition on cryogenic equipment and systems can result in serious problems and huge economic loss. Hence, it is quite necessary to develop new materials to prevent icing and frosting on cold surfaces in engineering fields. Here, a superhydrophobic aluminum alloy with enhanced anti-frosting, anti-icing, and self-cleaning performance has been developed by a facile one-step method. The anti-frosting/icing performance of superhydrophobic aluminum alloys is confirmed by frosting/icing time delay, consolidating and freezing temperature reduction, and lower amount of frost/ice adhesion. Meanwhile, the excellent self-cleaning performance is authenticated by the fact that simulated pollution particles can be cleaned out by rolling water droplets completely. Finally, based on the classical nucleation theory, anti-icing and anti-frosting mechanisms of the superhydrophobic aluminum alloys are deduced. Results show that grounded on "air cushion" and "heat insulation" effect, a larger nucleation barrier and a lower crystal growth rate can be observed, which, hence, inhibit ice formation and frost deposition. It can be concluded that preparing superhydrophobic surfaces would be an effective strategy for improving anti-icing, anti-frosting, and self-cleaning performance of aluminum alloys.

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.

Stress Ratio Effects on Crack Opening Loads and Crack Growth Rates in Aluminum Alloy 2024

NASA Technical Reports Server (NTRS)

Riddell, William T.; Piascik, Robert S.

1998-01-01

The effects of stress ratio (R) and crack opening behavior on fatigue crack growth rates (da/dN) for aluminum alloy (AA) 2024-T3 were investigated using constant-delta K testing, closure measurements, and fractography. Fatigue crack growth rates were obtained for a range of delta K and stress ratios. Results show that constant delta K fatigue crack growth for R ranging from near 0 to 1 is divided into three regions. In Region 1, at low R, da/dN increases with increasing R. In Region 2, at intermediate R, fatigue crack growth rates are relatively independent of R. In Region 3, at high R, further increases in da/dN are observed with increasing R.

Evolution of residual stresses in micro-arc oxidation ceramic coatings on 6061 Al alloy

NASA Astrophysics Data System (ADS)

Shen, Dejiu; Cai, Jingrui; Guo, Changhong; Liu, Peiyu

2013-11-01

Most researches on micro-arc oxidation mainly focus on the application rather than discovering the evolution of residual stresses. However, residual stresses in the surface coatings of structural components have adverse effects on their properties, such as fatigue life, dimensional stability and corrosion resistance, etc. The micro-arc oxidation ceramic coatings are produced on the surfaces of 6061 aluminum alloy by a homemade asymmetric AC type of micro-arc oxidation equipment of 20 kW. A constant current density of 4.4±0.1 A/dm2 and a self-regulated composite electrolyte are used. The micro-arc oxidation treatment period ranges from 10 min to 40 min, and the thickness of the ceramic coatings is more than 20 μm. Residual stresses attributed to γ-Al2O3 constituent in the coatings at different micro-arc oxidation periods are analyzed by an X-ray diffractometer using the sin2 ψ method. The analysis results show that the residual stress in the ceramic coatings is compressive in nature, and it increases first and then decreases with micro-arc oxidation time increase. The maximum stress value is 1 667±20 MPa for period of 20 min. Through analyzing the coating thickness, surface morphology and phase composition, it is found that the residual stress in the ceramic coatings is linked closely with the coating growth, the phase composition and the micro cracks formed. It is also found that both the heat treatment and the ultrasonic action release remarkably the residual compressive stress. The heat treatment makes the residual compressive stress value decrease 1 378 MPa. The ultrasonic action even alters the nature of the residual stress, making the residual compressive stress change into a residual tensile stress.

Eutectic structures in friction spot welding joint of aluminum alloy to copper

NASA Astrophysics Data System (ADS)

Shen, Junjun; Suhuddin, Uceu F. H.; Cardillo, Maria E. B.; dos Santos, Jorge F.

2014-05-01

A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl2 eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting.

Laser Surface Alloying of Aluminum for Improving Acid Corrosion Resistance

NASA Astrophysics Data System (ADS)

Jiru, Woldetinsay Gutu; Sankar, Mamilla Ravi; Dixit, Uday Shanker

2018-04-01

In the present study, laser surface alloying of aluminum with magnesium, manganese, titanium and zinc, respectively, was carried out to improve acid corrosion resistance. Laser surface alloying was conducted using 1600 and 1800 W power source using CO2 laser. Acid corrosion resistance was tested by dipping the samples in a solution of 2.5% H2SO4 for 200 h. The weight loss due to acid corrosion was reduced by 55% for AlTi, 41% for AlMg alloy, 36% for AlZn and 22% for AlMn alloy. Laser surface alloyed samples offered greater corrosion resistance than the aluminum substrate. It was observed that localized pitting corrosion was the major factor to damage the surface when exposed for a long time. The hardness after laser surface alloying was increased by a factor of 8.7, 3.4, 2.7 and 2 by alloying with Mn, Mg, Ti and Zn, respectively. After corrosion test, hardness was reduced by 51% for AlTi sample, 40% for AlMg sample, 41.4% for AlMn sample and 33% for AlZn sample.

Effect of Fe- and Si-Enriched Secondary Precipitates and Surface Roughness on Pore Formation on Aluminum Plate Surfaces During Anodizing

NASA Astrophysics Data System (ADS)

Zhu, Yuanzhi; Wang, Shizhi; Yang, Qingda; Zhou, Feng

2014-09-01

Two twin roll casts (TRCs) and one hot rolled (HR) AA 1235 aluminum alloy plates with different microstructures are prepared. The plates were electrolyzed in a 1.2 wt% HCl solution with a voltage of 21 V and a current of 1.9 mA. The shape, size, and number of pores formed on the surfaces of these plates were analyzed and correlated with the microstructures of the plates. It is found that pores are easier to form on the alloy plates containing subgrains with a lower dislocation density inside the subgrains, rather than along the grain boundaries. Furthermore, Fe- and Si-enriched particles in the AA1235 aluminum alloys lead to the formation of pores on the surface during electrolyzing; the average precipitate sizes of 4, 3.5, and 2 μm in Alloy 1#, Alloy 2# and Alloy 3# result in the average pore sizes of 3.78, 2.76, and 1.9 μm on the surfaces of the three alloys, respectively; The G.P zone in the alloy also facilitates the surface pore formation. High-surface roughness enhances the possibility of entrapping more lubricants into the plate surface, which eventually blocks the formation of the pores on the surface of the aluminum plates in the following electrolyzing process.

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.

Effect of Intensive Plastic Deformation on Microstructure and Mechanical Properties of Aluminum Alloys

NASA Astrophysics Data System (ADS)

Rakhadilov, Bauyrzhan; Uazyrkhanova, Gulzhaz; Myakinin, Alexandr; Uazyrkhanova, Zhuldyz

2016-08-01

In work it was studied the influence of intensive plastic deformation on structure and mechanical properties of aluminum alloys. Intensive plastic deformation was carried out by using equal-channel angular extrusion. It is shown that the most efficient angle of intersection of the channels is the angle of Φ=120°, which ensures defect-free parts at the highest possible level of accumulated strain (e=8). It is established that the intensive milling grain structures in aluminum alloys AMG6 and AMC occurs at ECAE-12 passes, while the intersection angle of the channels of 120°. After ECAE-12 in aluminum alloys the grain refinement reaches to the size of ∼⃒1.0-1.5 gm. It is determined that as a result of equal channel angular pressing, the microhardness of alloy AMG6 increases almost 4 times in comparison with the initial state, the microhardness of alloy AMC increases by almost 4.5 times in comparison with the initial state. It is shown that ECAE-12 mass loss is reduced to 5.4 and 5.6 mg, which shows an increase in wear-resistance of aluminum alloys AMG6 and AMC 13-14 %.

Study on the rheoformability of semi-solid 7075 wrought aluminum alloy using seed process =

NASA Astrophysics Data System (ADS)

Zhao, Qinfu

Semisolid metal forming is becoming more and more attractive in the foundry industry due to its low cost and easy operation to produce high quality near-net-shape components. Over the past years, semisolid forming technique is mainly applied on the casting aluminum alloys due to their superior castability because of low melting temperature and viscosity. In semisolid forming field, thixoforming has been majorly used which involves of reheating the billet into semisolid state followed by casting process. Rheocasting is a more economic semisolid processing compared to thixoforming, which the semisolid billet is produced directly from liquid phase. The SEED process is one of reliable rheocasting techniques to produce high quality semisolid billets. To produce high quality semisolid billets, their unique rheological properties have been the most important issue need to be fully investigated. The aim of present project is to produce high quality semisolid AA7075 billets by SEED process and analyze their rheological properties under various process conditions. The effect of the SEED processing parameters and grain refiners on the semisolid microstructure and rheoformability were investigated. The deformation and rheological behavior of the semisolid billets of AA7075 base and its grain-refined alloys were studied using parallel-plate viscometer. In the first part, the evolution of liquid fraction to temperature of semisolid AA7075 alloy was investigated using Differential Scanning Calorimetry (DSC). It was found that the liquidus and solidus temperature of AA7075 alloy were 631 °C and 490°C respectively. And the corresponding temperatures of solid fraction of 40% and 60% were 622°C and 610°C, which was recognized as the temperature window for semisolid forming of this alloy. In the second part, the semisolid slurries were rheocasted using SEED technology and the effect of the SEED process parameters like swirling frequency and demolding temperature on evolution of

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.

Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading Conditions

DTIC Science & Technology

2013-01-01

REPORT Friction Stir Weld Failure Mechanisms in Aluminum -Armor Structures Under Ballistic Impact Loading Conditions 14. ABSTRACT 16. SECURITY...Stir Weld Failure Mechanisms in Aluminum -Armor Structures Under Ballistic Impact Loading Conditions M. Grujicic, B. Pandurangan, A. Arakere, C-F. Yen...K.O. Pedersen, Fracture Mechanisms of Aluminum Alloy AA7075-T651 Under Various Loading Conditions , Int. J. Impact Eng., 2010, 37, p 537–551 24. T

Eutectic structures in friction spot welding joint of aluminum alloy to copper

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Junjun, E-mail: junjun.shen@hzg.de; Suhuddin, Uceu F. H.; Cardillo, Maria E. B.

2014-05-12

A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl{sub 2} eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting.

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.

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.

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.

First wall design of aluminum alloy R-tokamak

NASA Astrophysics Data System (ADS)

Hamada, Y.; Matsuoka, K.; Ogawa, Y.; Kitagawa, S.; Toi, K.; Yamazaki, K.; Abe, Y.; Amano, T.; Fujita, J.; Kaneko, O.; Kawahata, K.; Kuroda, T.; Matsuura, K.; Midzuno, Y.; Naitou, H.; Noda, N.; Ohkubo, K.; Oka, Y.; Sakurai, K.; Tanahashi, S.; Watari, T.

1984-05-01

A design study of a low-activation D-T tokamak Reacting Plasma Project In Nagoya has been finished. The study emphasizes the vacuum vessel and the bumper limiter. Our choice of materials (aluminum vacuum vessel, copper conductors, aluminum TF coil case and lead shield) results in a radiation level of about 1 × 10 -3 times that of a TFTR type design, and 1 × 10 -4 times that of JET type design, at 2 weeks after one D-T shot. Thick graphite tiles will be fixed directly on the aluminum vacuum vessel using aluminum spring washers and bolts. With this simplified structure of the bumper limiter, the inner surface temperature of the thick aluminum vacuum vessel will be less than 120°C which is required to reduce the overaging effect of the aluminum alloy.

Nitrate reduction in water by aluminum alloys particles.

PubMed

Bao, Zunsheng; Hu, Qing; Qi, Weikang; Tang, Yang; Wang, Wei; Wan, Pingyu; Chao, Jingbo; Yang, Xiao Jin

2017-07-01

Nano zero-valent iron (NZVI) particles have been extensively investigated for nitrate reduction in water. However, the reduction by NZVI requires acidic pH conditions and the final product is exclusively ammonium, leading to secondary contamination. In addition, nanomaterials have potential threats to environment and the transport and storage of nanomaterials are of safety concerns. Aluminum, the most abundant metal element in the earth's crust, is able to reduce nitrate, but the passivation of aluminum limits its application. Here we report Al alloys (85% Al) with Fe, Cu or Si for aqueous nitrate reduction. The Al alloys particles of 0.85-0.08 mm were inactivate under ambient conditions and a simple treatment with warm water (45 °C) quickly activated the alloy particles for rapid reduction of nitrate. The Al-Fe alloy particles at a dosage of 5 g/L rapidly reduced 50 mg-N/L nitrate at a reaction rate constant (k) of 3.2 ± 0.1 (mg-N/L) 1.5 /min between pH 5-6 and at 4.0 ± 0.1 (mg-N/L) 1.5 /min between pH 9-11. Dopping Cu in the Al-Fe alloy enhanced the rates of reduction whereas dopping Si reduced the reactivity of the Al-Fe alloy. The Al alloys converted nitrate to 20% nitrogen and 80% ammonium. Al in the alloy particles provided electrons for the reduction and the intermetallic compounds in the alloys were likely to catalyze nitrate reduction to nitrogen. Copyright © 2017 Elsevier Ltd. All rights reserved.

Friction Stir Welding in Wrought and Cast Aluminum Alloys: Weld Quality Evaluation and Effects of Processing Parameters on Microstructure and Mechanical Properties

NASA Astrophysics Data System (ADS)

Pan, Yi; Lados, Diana A.

2017-04-01

Friction stir welding (FSW) is a solid-state process widely used for joining similar and dissimilar materials for critical applications in the transportation sector. Understanding the effects of the process on microstructure and mechanical properties is critical in design for structural integrity. In this study, four aluminum alloy systems (wrought 6061-T651 and cast A356, 319, and A390) were processed in both as-fabricated and pre-weld heat-treated (T6) conditions using various processing parameters. The effects of processing and heat treatment on the resulting microstructures, macro-/micro-hardness, and tensile properties were systematically investigated and mechanistically correlated to changes in grain size, characteristic phases, and strengthening precipitates. Tensile tests were performed at room temperature both along and across the welding zones. A new method able to evaluate weld quality (using a weld quality index) was developed based on the stress concentration calculated under tensile loading. Optimum processing parameter domains that provide both defect-free welds and good mechanical properties were determined for each alloy and associated with the thermal history of the process. These results were further related to characteristic microstructural features, which can be used for component design and materials/process optimization.

Dissimilar Impact Welding of 6111-T4, 5052-H32 Aluminum Alloys to 22MnB5, DP980 Steels and the Structure-Property Relationship of a Strongly Bonded Interface

NASA Astrophysics Data System (ADS)

Liu, Bert; Vivek, Anupam; Presley, Michael; Daehn, Glenn S.

2018-03-01

The ability to weld high-strength aluminum to high-strength steel is highly desired for vehicle lightweighting but difficult to attain by conventional means. In this work, vaporizing foil actuator welding was used to successfully weld four Al/Fe combinations consisting of high-strength alloys: AA5052-H32, AA6111-T4, DP980, and 22MnB5. Flyer velocities up to 727 m/s were reached using 10 kJ input energy. In lap-shear testing, samples primarily failed in base aluminum near the aluminum's native strength, showing that the welds were stronger than a base metal and that the base metal was not significantly weakened by the welding process. A particularly strong weld area was studied by transmission electron microscopy to shed light on the microstructural features of strong impact welds. It was found to be characterized by a continuously bonded, fully crystalline interface, extremely fine (nanoscale) grains, mesoscopic as well as microscopic wavy features, and lack of large continuous intermetallic compounds.

The Study on the Overall Plasma Electrolytic Oxidation for 6061–7075 Dissimilar Aluminum Alloy Welded Parts Based on the Dielectric Breakdown Theory

PubMed Central

Song, Xiaocun; Zhou, Jixue; Liu, Hongtao; Yang, Yuansheng

2018-01-01

Electrical connection of dissimilar metals will lead to galvanic corrosion. Therefore, overall surface treatment is necessary for the protection of dissimilar metal welded parts. However, serious unbalanced reactions may occur during overall surface treatment, which makes it difficult to prepare integral coating. In this paper, an overall ceramic coating was fabricated by plasma electrolytic oxidation to wrap the 6061–7075 welded part integrally. Moreover, the growth mechanism of the coating on different areas of the welded part was studied based on the dielectric breakdown theory. The reaction sequence of each area during the treatment was verified through specially designed dielectric breakdown tests. The results showed that the high impedance overall of ceramic coating can inhibit the galvanic corrosion of the 6061–7075 welded part effectively. PMID:29301306

Effect of Preexisting Corrosion on Fatigue Cracking of Aluminum Alloys 2024-T3 and 7075-T6

DTIC Science & Technology

1995-08-01

alloys 2024 -T3 and 7075-T6. It was determined that preexisting corrosion has a detrimental effect on the fatigue life of aluminum alloys 2024 -T3 and...following conclusions were drawn: 1. Preexisting corrosion has a detrimental effect on the fatigue life of aluminum alloys 2024 -T3 and 7075-T6. The...corrosion has a detrimental effect on the fatigue life of aluminum alloys

The behavior of ZrO2/20%Y2O3 and Al2O3 coatings deposited on aluminum alloys at high temperature regime

NASA Astrophysics Data System (ADS)

Pintilei, G. L.; Crismaru, V. I.; Abrudeanu, M.; Munteanu, C.; Baciu, E. R.; Istrate, B.; Basescu, N.

2015-10-01

Aluminum alloy present numerous advantages like lightness, high specific strength and diversity which recommend them to a high number of applications from different fields. In extreme environments the protection of aluminum alloys is difficult and requires a high number of requirements like high temperature resistance, thermal fatigue resistance, corrosion fatigue resistance and galvanic corrosion resistance. To obtain these characteristics coatings can be applied to the surfaces so they can enhance the mechanical and chemical properties of the parts. In this paper two coatings were considered for deposition on an AA2024 aluminum alloy, ZrO2/20%Y2O3 and Al2O3. To obtain a better adherence of the coating to the base material an additional bond layer of NiCr is used. Both the coatings and bond layer were deposited by atmospheric plasma spraying on the samples. The samples were subjected to a temperature of 500 °C and after that slowly cooled to room temperature. The samples were analyzed by electron microscopy and X-ray diffraction to determine the morphological and phase changes that occurred during the temperature exposure. To determine the stress level in the parts due to thermal expansion a finite element analysis was performed in the same conditions as the tests.

In-Situ Synthetic TiB2 Particulate Reinforced Metal Matrix Composite Coating on AA2024 Aluminum Alloy by Laser Cladding Technology

NASA Astrophysics Data System (ADS)

Xu, Jiang; Kan, Yide; Liu, Wenjin

In order to improve the wear resistance of aluminum alloy, in-situ synthesized TiB2 and Ti3B4 peritectic composite particulate reinforced metal matrix composite, formed on a 2024 aluminum alloy by laser cladding with a powder mixture of Fe-coated Boron, Ti and Al, was successfully achieved using 3-KW CW CO2 laser. The chemical composition, microstructure and phase structure of the composite clad coating were analyzed by energy dispersive X-ray spectroscopy (EDX), SEM, AFM and XRD. The typical microstructure of the composite coating is composed of TiB2, Ti3B4, Al3Ti, Al3Fe and α-Al. The surface hardness of cladding coating increases with the amount of added Fe-coated B and Ti powder which determines the amount of TiB2 and Ti3B4 peritectic composite particulate. The nanohardness and the elastic modulus at the interface of the TiB2 and Ti3B4 peritectic composite particulate/matrix were investigated using the nanoindentation technique. The results showed that the nanohardness and the reduced elastic modulus from the peritectic composite particulate to the matrix is a gradient distribution.

Thermomechanical processing of aluminum micro-alloyed with Sc, Zr, Ti, B, and C

NASA Astrophysics Data System (ADS)

McNamara, Cameron T.

Critical exploration of the minimalistic high strength low alloy aluminum (HSLA-Al) paradigm is necessary for the continued development of advanced aluminum alloys. In this study, scandium (Sc) and zirconium (Zr) are examined as the main precipitation strengthening additions, while magnesium (Mg) is added to probe the synergistic effects of solution and precipitation hardening, as well as the grain refinement during solidification afforded by a moderate growth restriction factor. Further, pathways of recrystallization are explored in several potential HSLA-Al syste =ms sans Sc. Aluminum-titanium-boron (Al-Ti-B) and aluminum-titanium-carbon (Al-Ti-C) grain refining master alloys are added to a series of Al-Zr alloys to examine both the reported Zr poisoning effect on grain size reduction and the impact on recrystallization resistance through the use of electron backscattered diffraction (EBSD) imaging. Results include an analysis of active strengthening mechanisms and advisement for both constitution and thermomechanical processing of HSLA-Al alloys for wrought or near-net shape cast components. The mechanisms of recrystallization are discussed for alloys which contain a bimodal distribution of particles, some of which act as nucleation sites for grain formation during annealing and others which restrict the growth of the newly formed grains.

The Effect of Impurities on the Processing of Aluminum Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zi-Kui Liu; Shengjun Zhang; Qingyou Han

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 thatmore » 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

Fabrication and tribological response of aluminium 6061 hybrid composite reinforced with bamboo char and boron carbide micro-fillers

NASA Astrophysics Data System (ADS)

Chethan, K. N.; Pai, Anand; Keni, Laxmikant G.; Singhal, Ashish; Sinha, Shubham

2018-02-01

Metal matrix composites (MMCs) have a wide scope of industrial applications and triumph over conventional materials due to their light weight, higher specific strength, good wear resistance and lower coefficient of thermal expansion. The present study aims at establishing the feasibility of using Bamboo charcoal particulate and boron carbide as reinforcements in Al-6061 alloy matrix and to investigate their effect on the wear of composites taking into consideration the interfacial adhesion of the reinforcements in the alloy. Al-6061 alloy was chosen as a base metallic alloy matrix. Sun-dried bamboo canes were used for charcoal preparation with the aid of a muffle furnace. The carbon content in the charcoal samples was determined by EDS (energy dispersive spectroscopy). In present study, stir casting technique was used to prepare the samples with 1%, 2%, and 3% weight of bamboo charcoal and boron carbide with Al-6061. The fabricated composites were homogenised at 570°C for 6 hours and cooled at room temperature. Wear studies were carried out on the specimens with different speed and loads. It was found that wear rate and coefficient of friction decreased with increase in the reinforcement content.

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.

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.

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

NASA Astrophysics Data System (ADS)

Suemitsu, M.; Miyamoto, N.

1984-03-01

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

Cleavage crystallography of liquid metal embrittled aluminum alloys

NASA Technical Reports Server (NTRS)

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

1991-01-01

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

Statistical Analysis of High-Cycle Fatigue Behavior of Friction Stir Welded AA5083-H321

DTIC Science & Technology

2011-01-01

durable structures are: (a) FSW is 111being used in a serial production of aluminum alloy -based 112ferryboat deck structures in Finland; (b) Al-Mg- Si -based...and strain-hardened/stabilized Al-Mg-Mn alloy ) are characterized by a relatively large statistical scatter. This scatter is closely related to the...associated with friction stir-welded (FSW) joints of AA5083-H321 (a solid-solution-strengthened and strain-hardened/stabilized Al-Mg-Mn alloy ) are

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.

Friction stir welding of T joints of dissimilar aluminum alloy: A review

NASA Astrophysics Data System (ADS)

Thakare, Shrikant B.; Kalyankar, Vivek D.

2018-04-01

Aluminum alloys are preferred in the mechanical design due to their advantages like high strength, good corrosion resistance, low density and good weldability. In various industrial applications T joints configuration of aluminum alloys are used. In different fields, T joints having skin (horizontal sheet) strengthen by stringers (vertical sheets) were used to increase the strength of structure without increasing the weight. T joints are usually carried out by fusion welding which has limitations in joining of aluminum alloy due to significant distortion and metallurgical defects. Some aluminum alloys are even non weldable by fusion welding. The friction stir welding (FSW) has an excellent replacement of conventional fusion welding for T joints. In this article, FSW of T joints is reviewed by considering aluminum alloy and various joint geometries for defect analysis. The previous experiments carried out on T joints shows the factors such as tool geometry, fixturing device and joint configurations plays significant role in defect free joints. It is essential to investigate the material flow during FSW to know joining mechanism and the formation of joint. In this study the defect occurred in the FSW are studied for various joint configurations and parameters. Also the effect of the parameters and defects occurs on the tensile strength are studied. It is concluded that the T-joints of different joint configurations can be pretended successfully. Comparing to base metal some loss in tensile strength was observed in the weldments as well as overall reduction of the hardness in the thermos mechanically affected zone also observed.

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.

Controlled Release from Core-Shell Nanoporous Silica Particles for Corrosion Inhibition of Aluminum Alloys

DOE PAGES

Jiang, Xingmao; Jiang, Ying-Bing; Liu, Nanguo; ...

2011-01-01

Ceriumore » m (Ce) corrosion inhibitors were encapsulated into hexagonally ordered nanoporous silica particles via single-step aerosol-assisted self-assembly. The core/shell structured particles are effective for corrosion inhibition of aluminum alloy AA2024-T3. Numerical simulation proved that the core-shell nanostructure delays the release process. The effective diffusion coefficient elucidated from release data for monodisperse particles in water was 1.0 × 10 − 14  m 2 s for Ce 3+ compared to 2.5 × 10 − 13  m 2 s for NaCl. The pore size, pore surface chemistry, and the inhibitor solubility are crucial factors for the application. Microporous hydrophobic particles encapsulating a less soluble corrosion inhibitor are desirable for long-term corrosion inhibition.« less

Alloying effect of copper concentration on the localized corrosion of aluminum alloy for heat exchanger tube

NASA Astrophysics Data System (ADS)

Hong, Min-Sung; Park, In-Jun; Kim, Jung-Gu

2017-07-01

This study examined the alloying effect of Cu content on the localized corrosion properties of Al alloy in synthetic acid rain containing 200 ppm of Cl- ion. In aluminum alloy tubes, a small amount of Cu is contained as the additive to improve the mechanical strength or as the impurity. The Cu-containing intermetallic compound, Al2Cu can cause galvanic corrosion because it has more noble potential than Al matrix. Therefore aluminum tube could be penetrated by localized corrosion attack. The results were obtained from electrochemical test, scanning electron microscopy, and time of flight secondary ion mass spectrometry (ToF-SIMS) mapping. Severe localized corrosion was occurred on the Al-0.03 wt% Cu alloy. The negative effect of Cu on the pitting corrosion was attributed to the presence of the Al2Cu precipitates.

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

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.

Fatigue Strength Estimation Based on Local Mechanical Properties for Aluminum Alloy FSW Joints

PubMed Central

Sillapasa, Kittima; Mutoh, Yoshiharu; Miyashita, Yukio; Seo, Nobushiro

2017-01-01

Overall fatigue strengths and hardness distributions of the aluminum alloy similar and dissimilar friction stir welding (FSW) joints were determined. The local fatigue strengths as well as local tensile strengths were also obtained by using small round bar specimens extracted from specific locations, such as the stir zone, heat affected zone, and base metal. It was found from the results that fatigue fracture of the FSW joint plate specimen occurred at the location of the lowest local fatigue strength as well as the lowest hardness, regardless of microstructural evolution. To estimate the fatigue strengths of aluminum alloy FSW joints from the hardness measurements, the relationship between fatigue strength and hardness for aluminum alloys was investigated based on the present experimental results and the available wide range of data from the references. It was found as: σa (R = −1) = 1.68 HV (σa is in MPa and HV has no unit). It was also confirmed that the estimated fatigue strengths were in good agreement with the experimental results for aluminum alloy FSW joints. PMID:28772543

Perforation of Thin Aluminum Alloy Plates by Blunt Projectiles - Experimental and Numerical Investigation

NASA Astrophysics Data System (ADS)

Wei, Gang; Zhang, Wei; Xiao, Xinke; Guo, Zitao

2011-06-01

Reducing the armor weight has become a research focus in terms of armored material with the increasing requirement of the mobility and flexibility of tanks and armored vehicles in modern local wars. Due to high strength-to-density ratio, aluminum alloy has become a potential light armored material. In this study, both lab-scale ballistic test and finite element simulation were adopted to examine the ballistic resistance of aluminum alloy targets. Blunt high strength steel projectiles with 12.7 mm diameter were launched by light gas gun against 3.3 mm thick aluminum alloy plates at velocity of 90 ~170 m/s. The ballistic limit velocity was obtained. Plugging failure and obvious structure deformation of targets were observed, and with the impact velocity increasing, the target structure deformation decrease gradually. Corresponding 2D finite element simulations were conducted by ABAQUS/EXPLICIT combined with material performance testing. Good agreement between the numerical simulations and the experimental results was found. Detailed computational results were provided to understand the deformation and failure mechanisms of the aluminum alloy plates.

Fatigue Strength Estimation Based on Local Mechanical Properties for Aluminum Alloy FSW Joints.

PubMed

Sillapasa, Kittima; Mutoh, Yoshiharu; Miyashita, Yukio; Seo, Nobushiro

2017-02-15

Overall fatigue strengths and hardness distributions of the aluminum alloy similar and dissimilar friction stir welding (FSW) joints were determined. The local fatigue strengths as well as local tensile strengths were also obtained by using small round bar specimens extracted from specific locations, such as the stir zone, heat affected zone, and base metal. It was found from the results that fatigue fracture of the FSW joint plate specimen occurred at the location of the lowest local fatigue strength as well as the lowest hardness, regardless of microstructural evolution. To estimate the fatigue strengths of aluminum alloy FSW joints from the hardness measurements, the relationship between fatigue strength and hardness for aluminum alloys was investigated based on the present experimental results and the available wide range of data from the references. It was found as: σ a ( R = -1) = 1.68 HV ( σ a is in MPa and HV has no unit). It was also confirmed that the estimated fatigue strengths were in good agreement with the experimental results for aluminum alloy FSW joints.

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%.

An Impact of Zirconium Doping of Zn-Al Braze on the Aluminum-Stainless Steel Joints Integrity During Aging

NASA Astrophysics Data System (ADS)

Yang, Jinlong; Xue, Songbai; Sekulic, Dusan P.

2017-01-01

This work offers an analysis of the microstructure and the growth rate of an intermetallic compound within the aged AA 6061 aluminum alloy-304 stainless steel joint brazed with Zn-15Al and Zn-15Al-0.2Zr filler metals. The effect of zirconium addition on mechanical integrity of the brazed joint was studied. The experimental results confirm that the thickness of the Fe-Al intermetallic layer formed at the brazed seam/stainless steel interface increases with the increase of the aging time. Furthermore, it is established that the growth rate of the intermetallic layer for the Zn-15Al-0.2Zr brazed joint was lower than that for Zn-15Al. The results also indicate that the shear strength of both Zn-15Al and Zn-15Al-0.2Zr brazed joints decreases monotonously during aging. The value of the strength after aging lasting for 800 h for Zn-15Al and Zn-15Al-0.2Zr has decreased by 20 and 17%, respectively. The fracture of joints occurred at the interface between the brazed seam and the Fe4Al13 intermetallic layer. The morphology of the surfaces exhibits a cleavage fracture.

Ballistic Experiments with Titanium and Aluminum Targets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gogolewski, R.; Morgan, B.R.

1999-11-23

During the course of the project we conducted two sets of fundamental experiments in penetration mechanics in the LLNL Terminal Ballistics Laboratory of the Physics Directorate. The first set of full-scale experiments was conducted with a 14.5mm air propelled launcher. The object of the experiments was to determine the ballistic limit speed of 6Al-4V-alloy titanium, low fineness ratio projectiles centrally impacting 2024-T3 alloy aluminum flat plates and the failure modes of the projectiles and the targets. The second set of one-third scale experiments was conducted with a 14.5mm powder launcher. The object of these experiments was to determine the ballisticmore » limit speed of 6Al-4V alloy titanium high fineness ratio projectiles centrally impacting 6Al-4V alloy titanium flat plates and the failure modes of the projectiles and the target. We employed radiography to observe a projectile just before and after interaction with a target plate. Early on, we employed a non-damaging ''soft-catch'' technique to capture projectiles after they perforated targets. Once we realized that a projectile was not damaged during interaction with a target, we used a 4-inch thick 6061-T6-alloy aluminum witness block with a 6.0-inch x 6.0-inch cross-section to measure projectile residual penetration. We have recorded and tabulated below projectile impact speed, projectile residual (post-impact) speed, projectile failure mode, target failure mode, and pertinent comments for the experiments. The ballistic techniques employed for the experiments are similar to those employed in an earlier study.« less

Biaxial Testing of 2219-T87 Aluminum Alloy Using Cruciform Specimens

NASA Technical Reports Server (NTRS)

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

1997-01-01

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

Effects of Forged Stock and Pure Aluminum Coating on Cryogenic Performance of Heat Treated Aluminum Mirrors

NASA Technical Reports Server (NTRS)

Toland, Ronald; Ohl, Raymond G.; Barthelmy, Michael P.; Zewari, S. Wahid; Greenhouse, Matthew A.; MacKenty, John W.

2003-01-01

In spite of its baseline mechanical stress relief, aluminum 6061-T651 harbors some residual stress that may relieve and distort mirror figure to unacceptable levels at cryogenic operating temperatures unless relieved during fabrication. Cryogenic instruments using aluminum mirrors for both ground-based and space IR astronomy have employed a variety of heat treatment formulae, with mixed results. We present the results of an on-going test program designed to empirically determine the effects of different stress relief procedures for aluminum mirrors. Earlier test results identified a preferred heat treatment for flat and spherical mirrors diamond turned from blanks cut out of Al6061-T651 plate stock. Further tests have been performed on mirrors from forged stock and one set from plate stock coated with Alumiplate(TM) aluminum coating to measure the effect of these variables on cryogenic performance. The mirrors are tested for figure error and radius of curvature at room temperature and at 80 K for three thermal cycles. We correlate the results of our optical testing with heat treatment and metallographic data.

Mechanical evaluation of aluminum alloy ring fixator.

PubMed

Tosborvorn, Somboon; Cheechareon, Sukrom; Ruttanuchun, Kittiput; Sirivedin, Suparerk; Rhienumporn, Chaitawat

2006-11-01

To test the homemade ring fixator as a tool for correction of bony deformity. The authors developed an aluminum alloy ring fixator and tested it to find out the accuracy of manufacturing and strength of the ring systems under axial load with the Roundness Testing Machine and Lloyd Universal Testing Machine. The mean diameter of the twenty five-drill holes was 6.5843872 +/- 0.0521594 mm (mean +/- SD). Distance between particular drill holes, which reflected the precision of drilling, had a high accuracy with standard deviation from 0.1138 to 0.1870 mm. The roundness of the rings was 0.2421376 +/- 0.12437977 mm (mean +/- SD). The system structure had minimal permanent deformity at breaking point, mean yield strength of the system was 4786.9 +/- 14.353 N (mean +/- SD). This was caused by the failure of the wire. Mean stiffness of the system was 127 N./mm. The aluminum alloy ring fixator was strong enough and well tolerated for clinical usage

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%.

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.

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.

Influence of Composition on the Environmental Impact of a Cast Aluminum Alloy

PubMed Central

Gómez, Patricia; Elduque, Daniel; Sarasa, Judith; Pina, Carmelo; Javierre, Carlos

2016-01-01

The influence of alloy composition on the environmental impact of the production of six aluminum casting alloys (Al Si12Cu1(Fe), Al Si5Mg, Al Si9Cu3Zn3Fe, Al Si10Mg(Fe), Al Si9Cu3(Fe)(Zn) and Al Si9) has been analyzed. In order to perform a more precise environmental impact calculation, Life Cycle Assessment (LCA) with ReCiPe Endpoint methodology has been used, with the EcoInvent v3 AlMg3 aluminum alloy dataset as a reference. This dataset has been updated with the material composition ranges of the mentioned alloys. The balanced, maximum and minimum environmental impact values have been obtained. In general, the overall impact of the studied aluminum alloys varies from 5.98 × 10−1 pts to 1.09 pts per kg, depending on the alloy composition. In the analysis of maximum and minimum environmental impact, the alloy that has the highest uncertainty is AlSi9Cu3(Fe)(Zn), with a range of ±9%. The elements that contribute the most to increase its impact are Copper and Tin. The environmental impact of a specific case, an LED luminaire housing made out of an Al Si12Cu1(Fe) cast alloy, has been studied, showing the importance of considering the composition. Significant differences with the standard datasets that are currently available in EcoInvent v3 have been found. PMID:28773536

Influence of Composition on the Environmental Impact of a Cast Aluminum Alloy.

PubMed

Gómez, Patricia; Elduque, Daniel; Sarasa, Judith; Pina, Carmelo; Javierre, Carlos

2016-05-25

The influence of alloy composition on the environmental impact of the production of six aluminum casting alloys (Al Si12Cu1(Fe), Al Si5Mg, Al Si9Cu3Zn3Fe, Al Si10Mg(Fe), Al Si9Cu3(Fe)(Zn) and Al Si9) has been analyzed. In order to perform a more precise environmental impact calculation, Life Cycle Assessment (LCA) with ReCiPe Endpoint methodology has been used, with the EcoInvent v3 AlMg3 aluminum alloy dataset as a reference. This dataset has been updated with the material composition ranges of the mentioned alloys. The balanced, maximum and minimum environmental impact values have been obtained. In general, the overall impact of the studied aluminum alloys varies from 5.98 × 10 -1 pts to 1.09 pts per kg, depending on the alloy composition. In the analysis of maximum and minimum environmental impact, the alloy that has the highest uncertainty is AlSi9Cu3(Fe)(Zn), with a range of ±9%. The elements that contribute the most to increase its impact are Copper and Tin. The environmental impact of a specific case, an LED luminaire housing made out of an Al Si12Cu1(Fe) cast alloy, has been studied, showing the importance of considering the composition. Significant differences with the standard datasets that are currently available in EcoInvent v3 have been found.

High-temperature, low-cycle fatigue behavior of an Al-Mg-Si based heat-resistant aluminum alloy

NASA Astrophysics Data System (ADS)

Kim, Kyu-Sik; Sung, Si-Young; Han, Bum-Suck; Park, Joong-Cheol; Lee, Kee-Ahn

2015-11-01

High-temperature, low-cycle fatigue behavior of the new heat-resistant aluminum alloy was investigated in this study. The aluminum alloy consists of aluminum matrix and small amount of precipitated Mg2Si and (Co, Ni)3Al4 strengthening particles. At room temperature and 523 K, the yield and tensile strengths of Al-Mg-Si-(Co, Ni) the aluminum alloy were maintained with no significant decrease, and elongation increased slightly. Low-cycle fatigue tests controlled by total strain were performed with strain ratio (R) = -1, strain rate = 2×10-3 s-1 at 523 K. The fatigue limit of the low-cycle fatigue of this alloy showed plastic strain amplitude (Δ ɛ pa) of 0.22% at 103 cycles. This value was superior to that of conventional aluminum alloy such as A319. The results of the fractographical observation showed that second phases, especially (Co, Ni)3Al4 particles, affected fatigue behavior. This study also attempted to clarify the mechanism of high-temperature, low-cycle fatigue deformation of Al-Mg-Si-(Co, Ni) alloy in relation to its microstructure and energy dissipation analysis.

New weldable high strength aluminum alloy developed for cryogenic service

NASA Technical Reports Server (NTRS)

1966-01-01

Wrought aluminum alloy has improved low temperature notch toughness and weldability. This alloy can be mill-fabricated to plate and sheet without difficulty. Post-weld aging improves weld ductility and strength properties. A typical treatment is 8 hours at 225 deg F plus 16 hours at 300 deg F.

The Effect of Alloying Elements on Thermal Conductivity and Casting Characteristic in High Pressure Die Casting of Aluminum Alloy

NASA Astrophysics Data System (ADS)

Kim, Cheol-Woo; Cho, Jae-Ik; Choi, Se-Weon; Kim, Young-Chan; Kang, Chang-Seog

Recently, demand of aluminum alloys for use in high thermal conductivity application is increases but the most aluminum die casting alloys exhibit very lower thermal properties because of their high concentrations of alloying elements. However, those alloying elements are essential to obtain sufficient fluidity and mechanical strength. Therefore, the purpose of this study is to analyze the effect of alloying elements in die casting alloys, Si, Cu, Mg, Fe and Mn, in thermal conductivity, die casting characteristics and mechanical properties and find out the appropriate amount of each alloying element for development of heat sink component. The results showed that Mn had the most deleterious effect in thermal conductivity and Si and Fe contents were important to improve strength and limit casting defects, such as hot tearing and die soldering. The alloy with 0.2 1.0wt%Cu, 0.3 0.6wt%Fe and 1.0 2.0wt%Si showed very good combination of high thermal conductivity and good casting characteristics.

Review and Study of Physics Driven Pitting Corrosion Modeling in 2024-T3 Aluminum Alloys (Postprint)

DTIC Science & Technology

2015-05-01

AFRL-RX-WP-JA-2015-0218 REVIEW AND STUDY OF PHYSICS DRIVEN PITTING CORROSION MODELING IN 2024-T3 ALUMINUM ALLOYS (POSTPRINT) Lingyu...2014 – 1 April 2015 4. TITLE AND SUBTITLE REVIEW AND STUDY OF PHYSICS DRIVEN PITTING CORROSION MODELING IN 2024-T3 ALUMINUM ALLOYS (POSTPRINT) 5a...18 Review and Study of Physics Driven Pitting Corrosion Modeling in 2024-T3 Aluminum Alloys Lingyu Yu 1*, Kumar V. Jata2 1Mechanical Engineering

Dry sliding behavior of aluminum alloy 8011 with 12% fly ash composites

NASA Astrophysics Data System (ADS)

Magibalan, S.; Senthilkumar, P.; Palanivelu, R.; Senthilkumar, C.; Shivasankaran, N.; Prabu, M.

2018-05-01

This research focused on the fabrication of aluminum alloy 8011 with 12% fly ash (FA) composite (AA8011%–12% FA) using the stir casting method. A three-level central composite design experiment was developed using response surface methodology with various parameters such as load, time, and sliding velocity varied in the range of 5 to 15 N, 5 to 15 min, and 1.5 to 4.5 m.s‑1, respectively. Dry sliding wear tests were performed as per the experimental design using a pin on disc at room temperature. The obtained regression result indicated that the developed model performed well in relating the wear process parameters and predicted the wear behavior of the composite. The surface plot showed that the wear rate increases with increase in load, time, and sliding velocity. Hardness was evaluated by Vickers hardness testing machine. Moreover, the surface morphology of the worn-out composite was examined using a scanning electron microscope.

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. (c) 2007 Wiley Periodicals, Inc.

Thermomechanical treatment of welded joints of aluminum-lithium alloys modified by scandium

NASA Astrophysics Data System (ADS)

Malikov, A. G.

2017-12-01

At present, the aeronautical equipment manufacture involves up-to-date high-strength aluminum alloys of decreased density resulting from the lithium admixture. Various technologies of fusible welding of these alloys are being developed. The paper presents experimental investigations of the optimization of the laser welding of aluminum alloys with the scandium-modified welded joint after thermomechanical treatment. The effect of scandium on the micro- and macrostructure is studied along with strength characteristics of the welded joint. It is found that thermomechanical treatment allows us to obtain the strength of the welded joint 0.89 for the Al-Mg-Li system and 0.99 for the Al-Cu-Li system with the welded joint modified by scandium in comparison with the base alloy after treatment.

The effect of laser surface melting on microstructure and corrosion behavior of friction stir welded aluminum alloy 2219

NASA Astrophysics Data System (ADS)

Ma, Shengchong; Zhao, Yong; Zou, Jiasheng; Yan, Keng; Liu, Chuan

2017-11-01

This study aimed to explore the electrochemical properties and microstructure of friction stir welds to understand the correlation between their properties and processing. Friction stir welding is a promising solid-state joining process for high-strength aluminum alloys (AA). Although friction stir welding (FSW) eliminates the problems of fusion welding due to the fact that it is performed below Tm, it causes severe plastic deformation in the material. Some AA welded by FSW exhibit relatively poor corrosion resistance. In this research, the corrosion resistance of such welds was enhanced through laser surface melting. A friction stir weld of AA 2219 was laser melted. The melt depth and microstructure were observed using optical and scanning electron microscopy. The melt zone exhibited epitaxially grown columnar grains. The redistribution of elemental composition was analyzed using energy-dispersive spectroscopy. The anticorrosion properties of both laser-melted and original welds were studied in aqueous 3.5% NaCl solution using cyclic potentiodynamic polarization. The results indicated a noticeable increase in the pitting corrosion resistance after the laser treatment on the surface. The repassivation potential was nobler than the corrosion potential after the laser treatment, confirming that the resistance to pitting growth improved.

Effects of SiC whiskers and particles on precipitation in aluminum matrix composites

NASA Astrophysics Data System (ADS)

Papazian, John M.

1988-12-01

The age-hardening precipitation reactions in aluminum matrix composites reinforced with discontinuous SiC were studied using a calorimetric technique. Composites fabricated with 2124, 2219, 6061, and 7475 alloy matrices were obtained from commercial sources along with unreinforced control materials fabricated in a similar manner. The 7475 materials were made by a casting process while the others were made by powder metallurgy: the SiC reinforcement was in the form of whiskers or particulate. It was found that the overall age-hardening sequence of the alloy was not changed by the addition of SiC, but that the volume fractions of various phases and the precipitation kinetics were substantially modified. Precipitation and dissolution kinetics were generally accelerated. A substantial portion of this acceleration was found to be due to the powder metallurgy process employed to make the composites, but the formation kinetics of some particular precipitate phases were also strongly affected by the presence of SiC. It was observed that the volume fraction of GP zones able to form in the SiC containing materials was significantly reduced. The presence of SiC particles also caused normally quench insensitive materials such as 6061 to become quench sensitive. The microstructural origins of these effects are discussed.

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. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of Microstructure and Microhardness in Self-Reacting Friction Stir Welded AA2014-T6 and AA2219-T87

NASA Technical Reports Server (NTRS)

Horton, K. Renee; McGill, Preston; Barkey, Mark

2011-01-01

Friction stir welding (FSW) is a solid state welding process with potential advantages for aerospace and automotive industries dealing with light alloys. Self-reacting friction stir welding (SR-FSW) is one variation of the FSW process being developed at the National Aeronautics and Space Administration (NASA) for use in the fabrication of propellant tanks. This work reports on the microstructure and microhardness of SR-FSW between two dissimilar aluminum alloys. Specifically, the study examines the cross section of the weld joint formed between an AA2014-T6 plate on the advancing side and an AA2219-T87 plate on the retreating side. The microstructural analysis shows an irregularly displaced weld seam from the advancing side past the thermo-mechanical affected zone (TMAZ) into the weld nugget region. There are sharp variations in the microhardness across the weld. These variations are described in the paper and mechanisms for their formation are discussed.

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.

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

NASA Astrophysics Data System (ADS)

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

2013-01-01

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

Friction stir welding joint of dissimilar materials between AZ31B magnesium and 6061 aluminum alloys: Microstructure studies and mechanical characterizations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohammadi, J.; Behnamian, Y.; Mostafaei, A., E-mail: amir.mostafaei@gmail.com

2015-03-15

Friction stir welding is an efficient manufacturing method for joining dissimilar alloys, which can dramatically reduce grain sizes and offer high mechanical joint efficiency. Lap FSW joints between dissimilar AZ31B and Al 6061 alloy sheets were made at various tool rotation and travel speeds. Rotation and travel speeds varied between 560–1400 r/min and 16–40 mm/min respectively, where the ratio between these parameters was such that nearly constant pitch distances were applied during welding. X-ray diffraction pattern (XRD), optical microscopy images (OM), electron probe microanalysis (EPMA) and scanning electron microscopy equipped with an energy-dispersive X-ray spectroscopy (SEM-EDS) were used to investigatemore » the microstructures of the joints welded. Intermetallic phases including Al{sub 12}Mg{sub 17} (γ) and Al{sub 3}Mg{sub 2} (β) were detected in the weld zone (WZ). For different tool rotation speeds, the morphology of the microstructure in the stir zone changed significantly with travel speed. Lap shear tensile test results indicated that by simultaneously increasing the tool rotation and travel speeds to 1400 r/min and 40 mm/min, the joint tensile strength and ductility reached a maximum. Microhardness measurements and tensile stress–strain curves indicated that mechanical properties were affected by FSW parameters and mainly depended on the formation of intermetallic compounds in the weld zone. In addition, a debonding failure mode in the Al/Mg dissimilar weld nugget was investigated by SEM and surface fracture studies indicated that the presence of intermetallic compounds in the weld zone controlled the failure mode. XRD analysis of the fracture surface indicated the presence of brittle intermetallic compounds including Al{sub 12}Mg{sub 17} (γ) and Al{sub 3}Mg{sub 2} (β). - Highlights: • Dissimilar Al/Mg joint was obtained by lap friction stir welding technique. • Effect of rotation and travel speeds on the formation of intermetallic

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.

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.

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.

Mechanical Properties of Titanium and Aluminum Alloys at Cryogenic Temperatures

DTIC Science & Technology

1962-03-01

aluminum alloys. Table I is a tabulation of the chemical composition of the tita - nium alloys. The bar was 5/8 inch in diameter and the sheet 0.060 inch...Ti-6AI-4V Tensile azid yield strength data for both bar and sheet of this tita - nium alloy are shown in Figure A-3. Bar and sheet data show approxi...not recommended for low temperature applications. The remainder of the tita - nium alloys were tested from room temperature to -452 F. In general, Ti

Springback of aluminum alloy brazing sheet in warm forming

NASA Astrophysics Data System (ADS)

Han, Kyu Bin; George, Ryan; Kurukuri, Srihari; Worswick, Michael J.; Winkler, Sooky

2017-10-01

The use of aluminum is increasing in the automotive industry due to its high strength-to-weight ratio, recyclability and corrosion resistance. However, aluminum is prone to significant springback due to its low elastic modulus coupled with its high strength. In this paper, a warm forming process is studied to improve the springback characteristics of 0.2 mm thick brazing sheet with an AA3003 core and AA4045 clad. Warm forming decreases springback by lowering the flow stress. The parts formed have complex features and geometries that are representative of automotive heat exchangers. The key objective is to utilize warm forming to control the springback to improve the part flatness which enables the use of harder temper material with improved strength. The experiments are performed by using heated dies at several different temperatures up to 350 °C and the blanks are pre-heated in the dies. The measured springback showed a reduction in curvature and improved flatness after forming at higher temperatures, particularly for the harder temper material conditions.

A detailed investigation of the strain hardening response of aluminum alloyed Hadfield steel

NASA Astrophysics Data System (ADS)

Canadinc, Demircan

The unusual strain hardening response exhibited by Hadfield steel single and polycrystals under tensile loading was investigated. Hadfield steel, which deforms plastically through the competing mechanisms slip and twinning, was alloyed with aluminum in order to suppress twinning and study the role of slip only. To avoid complications due to a grained structure, only single crystals of the aluminum alloyed Hadfield steel were considered at the initial stage of the current study. As a result of alloying with aluminum, twinning was suppressed; however a significant increase in the strain hardening response was also present. A detailed microstructural analysis showed the presence of high-density dislocation walls that evolve in volume fraction due to plastic deformation and interaction with slip systems. The very high strain hardening rates exhibited by the aluminum alloyed Hadfield steel single crystals was attributed to the blockage of glide dislocations by the high-density dislocation walls. A crystal plasticity model was proposed, that accounts for the volume fraction evolution and rotation of the dense dislocation walls, as well as their interaction with the active slip systems. The novelty of the model lies in the simplicity of the constitutive equations that define the strain hardening, and the fact that it is based on experimental data regarding the microstructure. The success of the model was tested by its application to different crystallographic orientations, and finally the polycrystals of the aluminum alloyed Hadfield steel. Meanwhile, the capability of the model to predict texture was also observed through the rotation of the loading axis in single crystals. The ability of the model to capture the polycrystalline deformation response provides a venue for its utilization in other alloys that exhibit dislocation sheet structures.

In vitro and in vivo corrosion evaluation of nickel-chromium- and copper-aluminum-based alloys.

PubMed

Benatti, O F; Miranda, W G; Muench, A

2000-09-01

The low resistance to corrosion is the major problem related to the use of copper-aluminum alloys. This in vitro and in vivo study evaluated the corrosion of 2 copper-aluminum alloys (Cu-Al and Cu-Al-Zn) compared with a nickel-chromium alloy. For the in vitro test, specimens were immersed in the following 3 corrosion solutions: artificial saliva, 0.9% sodium chloride, and 1.0% sodium sulfide. For the in vivo test, specimens were embedded in complete dentures, so that one surface was left exposed. The 3 testing sites were (1) close to the oral mucosa (partial self-cleaning site), (2) surface exposed to the oral cavity (self-cleaning site), and (3) specimen bottom surface exposed to the saliva by means of a tunnel-shaped perforation (non-self-cleaning site). Almost no corrosion occurred with the nickel-chromium alloy, for either the in vitro or in vivo test. On the other hand, the 2 copper-aluminum-based alloys exhibited high corrosion in the sulfide solution. These same alloys also underwent high corrosion in non-self-cleaning sites for the in vivo test, although minimal attack was observed in self-cleaning sites. The nickel-chromium alloy presented high resistance to corrosion. Both copper-aluminum alloys showed considerable corrosion in the sulfide solution and clinically in the non-self-cleaning site. However, in self-cleaning sites these 2 alloys did not show substantial corrosion.

Oxidation resistant, thoria-dispersed nickel-chromium-aluminum alloy

NASA Technical Reports Server (NTRS)

Baranow, S.; Klingler, L. J.

1973-01-01

Modified thoria-dispersed nickel-chromium alloy has been developed that exhibits greatly improved resistance to high-temperature oxidation. Additions of aluminum have been made to change nature of protective oxide scale entirely and to essentially inhibit oxidation at temperatures up to 1260 C.

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.

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.

Stress Corrosion Cracking Behavior of LD10 Aluminum Alloy in UDMH and N2O4 propellant

NASA Astrophysics Data System (ADS)

Zhang, Youhong; Chang, Xinlong; Liu, Wanlei

2018-03-01

The LD10 aluminum alloy double cantilever beam specimens were corroded under the conditions of Unsymmetric Uimethyl Hydrazine (UDMH), Dinitrogen Tetroxide (N2O4), and 3.5% NaCl environment. The crack propagation behavior of the aluminum alloy in different corrosion environment was analyzed. The stress corrosion cracking behavior of aluminum alloy in N2O4 is relatively slight and there are not evident stress corrosion phenomenons founded in UDMH.

Mechanisms of fatigue crack retardation following single tensile overloads in powder metallurgy aluminum alloys

NASA Technical Reports Server (NTRS)

Bray, G. H.; Reynolds, A. P.; Starke, E. A., Jr.

1992-01-01

In ingot metallurgy (IM) alloys, the number of delay cycles following a single tensile overload typically increases from a minimum at an intermediate baseline stress intensity range, Delta-K(B), with decreasing Delta-K(B) approaching threshold and increasing Delta-K(B) approaching unstable fracture to produce a characteristic 'U' shaped curve. Two models have been proposed to explain this behavior. One model is based on the interaction between roughness and plasticity-induced closure, while the other model only utilizes plasticity-induced closure. This article examines these models, using experimental results from constant amplitude and single overload fatigue tests performed on two powder metallurgy (PM) aluminum alloys, AL-905XL and AA 8009. The results indicate that the 'U'-shaped curve is primarily due to plasticity-induced closure, and that the plasticity-induced retardation effect is through-thickness in nature, occurring in both the surface and interior regions. However, the retardation effect is greater at the surface, because the increase in plastic strain at the crack tip and overload plastic zone size are larger in the plane-stress surface regions than in the plane-strain interior regions. These results are not entirely consistent with either of the proposed models.

Superhydrophobic surface prepared by micro-milling and WEDM on aluminum alloy

NASA Astrophysics Data System (ADS)

Yanling, Wan; Jian, Yang; Huadong, Yu

2018-06-01

To simulate the hydrophobic microstructure of rice leaf surface, high-speed precision micro-milling machine was used to fabricate micro groove array structure on the surface of aluminum alloy. The micro-and nanostructure was constructed on the surface of the grooved convex platform by Wire Cut Electrical Discharge Machining (WEDM). The surface morphology and hydrophobic properties of the aluminum alloy microstructures fabricated by two processing methods were observed respectively, and the hydrophobic mechanism was analyzed. The results show that the contact angle was effectively improved from 49° up to 158.4° in the vertical direction, and 146.7° in the parallel direction. The change of surface wettability from hydrophilic to hydrophobic was realized. By comparison, the micro-and nanostructure fabricated by WEDM had improved the hydrophobic stability of the aluminum alloy surface while enlarging the contact Angle, and the micro-milling groove structure further amplified the contact angle and greatly reduced the contact area of the water droplet, it was also observed that the drop took longer to completely spread on the sample after WEDM.

Friction stir processing of an aluminum-magnesium alloy with pre-placing elemental titanium powder: In-situ formation of an Al{sub 3}Ti-reinforced nanocomposite and materials characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khodabakhshi, F., E-mail: farzadkhodabakhshi83@gmail.com; Simchi, A.; Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, 14588 Tehran

A fine-grained Al–Mg/Al{sub 3}Ti nanocomposite was fabricated by friction stir processing (FSP) of an aluminum-magnesium (AA5052) alloy with pre-placed titanium powder in the stirred zone. Microstructural evolutions and formation of intermetallic phases were analyzed by optical and electron microscopic techniques across the thickness section of the processed sheets. The microstructure of the nanocomposite consisted of a fine-grained aluminum matrix (1.5 µm), un-reacted titanium particles (<40 µm) and reinforcement particles of Al{sub 3}Ti (<100 nm) and Mg{sub 2}Si (<100 nm). Detailed microstructural analysis indicated solid-state interfacial reactions between the aluminum matrix and micro-sized titanium particles to form Al{sub 3}Ti intermetallic phase.more » The hard inclusions were then fractured and re-distributed in the metal matrix by the severe thermo-mechanical conditions imposed by FSP. Evaluation of mechanical properties by hardness measurement and uniaxial tensile test determined significant enhancement in the mechanical strength (by 2.5 order of magnetite) with a high ductility (~22%). Based on a dislocation-based model analysis, it was suggested that the strength enhancement was governed by grain refinement and the presence of hard inclusions (4 vol%) in the metal matrix. Fractographic studies also showed a ductile-brittle fracture mode for the nanocomposite compared with fully ductile rupture of the annealed alloy as well as the FSPed specimen without pre-placing titanium particles. - Highlights: • FSP was employed to fabricate in situ nanocomposite. • The AA5052 Al alloy with pre-placed micro-sized Ti particles were utilized. • The structural analysis was revealed that the in situ formation of Al{sub 3}Ti nanophase. • The SZ grain structure was refined by PSN and ZHP mechanisms during DRX. • Hardness and tensile strength were improved up to ~2.5 times with a good ductility.« less

The stress-corrosion cracking behavior of high-strength aluminum powder metallurgy alloys

NASA Astrophysics Data System (ADS)

Pickens, J. R.; Christodoulou, L.

1987-01-01

The susceptibility to stress-corrosion cracking (SCC) of rapidly solidified (RS) aluminum powder metallurgy (P/M) alloys 7090 and 7091, mechanically alloyed aluminum P/M alloy IN* 9052, and ingot metallurgy (I/M) alloys of similar compositions was compared using bolt-loaded double cantilever beam specimens. In addition, the effects of aging, grain size, grain boundary segregation, pre-exposure embrittlement, and loading mode on the SCC of 7091 were independently assessed. Finally, the data generated were used to elucidate the mechanisms of SCC in the three P/M alloys. The IN 9052 had the lowest SCC susceptibility of all alloys tested in the peak-strength condition, although no SCC was observed in the two RS alloys in the overaged condition. The susceptibility of the RS alloys was greater in the underaged than the peak-aged temper. We detected no significant differences in susceptibility of 7091 with grain sizes varying from 2 to 300 μm. Most of the crack advance during SCC of 7091 was by hydrogen embrittlement (HE). Furthermore, both RS alloys were found to be susceptible to preexposure embrittlement—also indicative of HE. The P/M alloys were less susceptible to SCC than the I/M alloys in all but one test.

Characterization of B4C-composite-reinforced aluminum alloy composites

NASA Astrophysics Data System (ADS)

Singh, Ram; Rai, R. N.

2018-04-01

Dry sliding wear tests conducted on Pin-on-disk wear test machine. The rotational speed of disc is ranging from (400-600rpm) and under loads ranging from (30-70 N) the contact time between the disc and pin is constant for each pin specimen of composites is 15 minute. In all manufacturing industries the uses of composite materials has been increasing globally, In the present study, an aluminum 5083 alloy is used as the matrix and 5% of weight percentage of Boron Carbide (B4C) as the reinforcing material. The composite is produced using stir casting technique. This is cost effective method. The aluminum 5083 matrix can be strengthened by reinforcing with hard ceramic particles like silicon carbide and boron carbide. In this experiment, aluminum 5083 alloy is selected as one of main material for making parts of the ship it has good mechanical properties, good corrosion resistance and it is can welded very easily and does have good strength. The samples are tested for hardness and tensile strength. The mechanical properties like Hardness can be increased by reinforcing aluminum 5083alloy 5% boron carbide (B4C) particles and tensile strength. Finally the Scanning Electron Microscope (SEM) analysis and EDS is done, which helps to study topography of composites and it produces images of a sample by scanning it with a focused beam of electrons and the presence of composition found in the matrix.

Local zone-wise elastic-plastic constitutive parameters of Laser-welded aluminium alloy 6061 using digital image correlation

NASA Astrophysics Data System (ADS)

Bai, Ruixiang; Wei, Yuepeng; Lei, Zhenkun; Jiang, Hao; Tao, Wang; Yan, Cheng; Li, Xiaolei

2018-02-01

The mechanical properties of aluminium alloys can be affected by the local high temperature in laser welding. In this paper, an inversion identification method of local zone-wise elastic-plastic constitutive parameters for laser welding of aluminium alloy 6061 was proposed based on full-field optical measurement data using digital image correlation (DIC). Three regions, i.e., the fusion zone, heat-affected zone, and base zone, of the laser-welded joint were distinguished by means of microstructure optical observation and micrometer hardness measurement. The stress data were obtained using a laser-welded specimen via a uniaxial tensile test. Meanwhile, the local strain data of the laser-welded specimen were obtained by the DIC technique. Thus, the stress-strain relationship for different local regions was established. Finally, the constitutive parameters of the Ramberg-Osgood model were identified by least-square fitting to the experimental stress-strain data. Experimental results revealed that the mechanical properties of the local zones of the welded joints clearly weakened, and these results are consistent with the results of the hardness measurement.