The Experts below are selected from a list of 2811 Experts worldwide ranked by ideXlab platform
Terence G. Langdon - One of the best experts on this subject based on the ideXlab platform.
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An investigation of cavitation in the tensile testing of a spray-Cast Aluminum Alloy processed by ECAP
Materials Science Forum, 2006Co-Authors: Megumi Kawasaki, Cheng Xu, Terence G. LangdonAbstract:A commercial Aluminum 7034 Alloy, produced by spray Casting and having an initial grain size of ~2.1 μm, was subjected to equal-channel angular pressing (ECAP) through six passes at 473 K. In the as-pressed condition, the microstructure was reasonably homogeneous and the grain size was reduced to an ultrafine grain size of ~0.3 μm. This Alloy contains MgZn2 and Al3Zr precipitates which restrict grain growth. In tensile testing at 673 K after processing by ECAP, an elongation of >1000% was achieved at a strain rate of 1.0 × 10-2 s-1 corresponding to high strain rate superplasticity. Quantitative cavity measurements were conducted on the specimens after tensile testing for both the as-received condition and after ECAP. These measurements reveal a significant number of small cavities in the samples and especially in the sample that exhibited a very high elongation. This paper describes the morphology of cavity development in the spray-Cast Aluminum Alloy in both the as-received and as-pressed condition.
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influence of ecap on precipitate distributions in a spray Cast Aluminum Alloy
Acta Materialia, 2005Co-Authors: Cheng Xu, Minoru Furukawa, Zenji Horita, Terence G. LangdonAbstract:Experiments were conducted to evaluate the influence of equal-channel angular pressing (ECAP) on the mechanical properties of a spray-Cast Aluminum 7034 Alloy. In the unpressed condition, the grain size of the Alloy was ~2.1 ?m and the microstructure contained an array of rod-like ?-phase (MgZn2) precipitates plus metastable ??-phase and Al3Zr particles. It is shown that ECAP processing at a temperature of 473 K has three significant effects. First, it refines the grain size to ~0.3 ?m. Second, the high stresses imposed in ECAP lead to a fragmentation of the rod-like MgZn2 precipitates into smaller particles with significant fragmentation occurring in the first pass and additional breaking in subsequent passes. Third, there is a partial loss of the metastable ??-phase. Tensile testing at room temperature revealed a significant reduction in the ultimate tensile strength after ECAP due to the loss of the hardening ??-phase. Tensile testing at 673 K gave superplastic ductilities provided samples were pressed through a sufficient number of passes to achieve a reasonably large fraction of high-angle boundaries.
D M Maijer - One of the best experts on this subject based on the ideXlab platform.
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Through process Modeling applied to the fatigue design of Cast A356-T6 components
Engineering Fracture Mechanics, 2018Co-Authors: M. Iben Houria, D M Maijer, Y. Nadot, R. Fathallah, A.-l. GorgeAbstract:The optimization of Cast Aluminum Alloy components is proposed using a Through Process Modeling (TPM) methodology applied to the fatigue design. A full manufacturing process simulation of a Cast Aluminum Alloy A356 component is described. The modeling strategy presented in this paper is able to simulate the defect size, microstructure size and thermal history during the Casting process. The microstructure and defect simulated are the Secondary Dendrite Arm Spacing (SDAS) and maximum pore size, respectively. Based on the Defect Stress Gradient approach (DSG) published in a previous work, the fatigue limit is predicted as a function of the SDAS and defect size. Tension fatigue tests have been performed on bespoke prototype Cast component samples with various SDAS and defect size. The comparison between experimental results and the TPM simulation shows good agreement in terms of simulated heat transfer rates, defect size, SDAS and fatigue limit except for defect sizes greater than 500 µm.
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Development of a 3D Filling Model of Low-Pressure Die-Cast Aluminum Alloy Wheels
Metallurgical and Materials Transactions A, 2013Co-Authors: Jianglan Duan, S. L. Cockcroft, D M Maijer, Carl ReillyAbstract:A two-phase computational fluid dynamics model of the low-pressure die-Cast process for the production of A356 Aluminum Alloy wheels has been developed to predict the flow conditions during die filling. The filling model represents a 36-deg section of a production wheel, and was developed within the commercial finite-volume package, ANSYS CFX, assuming isothermal conditions. To fully understand the behavior of the free surface, a novel technique was developed to approximate the vent resistances as they impact on the development of a backpressure within the die cavity. The filling model was first validated against experimental data, and then was used to investigate the effects of venting conditions and pressure curves during die filling. It was found that vent resistance and vent location strongly affected die filling time, free surface topography, and air entrainment for a given pressure fill-curve. With regard to the pressure curve, the model revealed a strong relation between the pressure curve and the flow behavior in the hub, which is an area prone to defect formation.
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Prediction of fatigue performance in Cast Aluminum Alloy components
2006Co-Authors: Trevor C. Lindley, Peifeng Li, D M MaijerAbstract:The influence of Casting process conditions on the microstructure (secondary dendrite arm spacing, morphology of eutectic silicon and Fe-rich intermetallic particles) and defect populations (pores and oxide films) has been studied in Cast Aluminum Alloys. The effects of eutectic modifiers (Sr), grain refiners (TiB2), solidification rate and HIPing upon the size, distribution and complex three dimensional shape of the pores formed were characterized using three dimensional (3D) X-ray tomography. This method gave more realistic dimensioning of pores compared to conventional metallography.S-N fatigue properties were established for each Cast condition after T6 heat treatment. Scanning electron microscopy and fractographic examination were used to reveal the defect responsible for fatigue crack initiation.Models for situations where either crack initiation or small crack growth constituted the dominant phase of fatigue life were reviewed before formulating a unified methodology for the prediction of fatigue life of Cast components.
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Casting defects in low-pressure die-Cast Aluminum Alloy wheels
Jom, 2005Co-Authors: B. Zhang, S. L. Cockcroft, J. D. Zhu, D M Maijer, André Bernard PhillionAbstract:Defects in automotive Aluminum Alloy Casting continue to challenge metallurgists and production engineers as greater emphasis is placed on product quality and production cost. A range of Casting-related defects found in low-pressure die-Cast Aluminum wheels were examined metallographically in samples taken from several industrial wheel-Casting facilities. The defects examined include macro- and micro- porosity, entrained oxide films, and exogenous oxide inclusions. Particular emphasis is placed on the impact of these defects with respect to the three main Casting-related criteria by which automotive wheel quality are judged: wheel cosmetics, air-tightness, and wheel mechanical performance.
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tensile properties of as Cast Aluminum Alloy aa5182 close to the solidus temperature
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2004Co-Authors: L J Colley, M A Wells, D M MaijerAbstract:Abstract In response to the demand for accurate mechanical property data in the partially solidified state, an experimental apparatus has been developed to perform tensile measurements of Aluminum Alloys at temperatures close to the solidus temperature. Measurements of the tensile properties of an industrially direct chill Cast AA5182 Aluminum Alloy have been carried out at temperatures between 500 and 580 °C, at a range of strain rates between ∼10 −2 and ∼10 −4 s −1 . The fracture surfaces and microstructures of the tested specimens have been examined using optical and scanning electron microscopy in an attempt to correlate tensile properties with fracture behaviour and changes in microstructure. These properties have also been linked to the liquid fraction present in the specimen based on data found in the literature.
Angga Afrinaldi - One of the best experts on this subject based on the ideXlab platform.
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effect of friction stir processing conditions on fatigue behavior and texture development in a356 t6 Cast Aluminum Alloy
International Journal of Fatigue, 2015Co-Authors: Akiko Tajiri, Yoshihiko Uematsu, Toshifumi Kakiuchi, Yasunari Tozaki, Yosuke Suzuki, Angga AfrinaldiAbstract:Abstract Friction stir processing (FSP) was applied to A356-T6 Cast Aluminum Alloy to modify the microstructure and to eliminate Casting defects under two different tool rotational speeds. Plane bending fatigue tests had been conducted, revealing that FSP could enhance the fatigue strength where the lower rotational speed condition gave better results. The enhancement of fatigue strength was attributed to the elimination of Casting defects. Crystallographic analysis by EBSD revealed that the texture induced by FSP had detrimental effect on growth resistance. The lower rotational speed condition resulted in the weaker texture, and consequently, further increase of fatigue strength was achieved compared with the higher rotational speed condition.
Cheng Xu - One of the best experts on this subject based on the ideXlab platform.
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An investigation of cavitation in the tensile testing of a spray-Cast Aluminum Alloy processed by ECAP
Materials Science Forum, 2006Co-Authors: Megumi Kawasaki, Cheng Xu, Terence G. LangdonAbstract:A commercial Aluminum 7034 Alloy, produced by spray Casting and having an initial grain size of ~2.1 μm, was subjected to equal-channel angular pressing (ECAP) through six passes at 473 K. In the as-pressed condition, the microstructure was reasonably homogeneous and the grain size was reduced to an ultrafine grain size of ~0.3 μm. This Alloy contains MgZn2 and Al3Zr precipitates which restrict grain growth. In tensile testing at 673 K after processing by ECAP, an elongation of >1000% was achieved at a strain rate of 1.0 × 10-2 s-1 corresponding to high strain rate superplasticity. Quantitative cavity measurements were conducted on the specimens after tensile testing for both the as-received condition and after ECAP. These measurements reveal a significant number of small cavities in the samples and especially in the sample that exhibited a very high elongation. This paper describes the morphology of cavity development in the spray-Cast Aluminum Alloy in both the as-received and as-pressed condition.
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influence of ecap on precipitate distributions in a spray Cast Aluminum Alloy
Acta Materialia, 2005Co-Authors: Cheng Xu, Minoru Furukawa, Zenji Horita, Terence G. LangdonAbstract:Experiments were conducted to evaluate the influence of equal-channel angular pressing (ECAP) on the mechanical properties of a spray-Cast Aluminum 7034 Alloy. In the unpressed condition, the grain size of the Alloy was ~2.1 ?m and the microstructure contained an array of rod-like ?-phase (MgZn2) precipitates plus metastable ??-phase and Al3Zr particles. It is shown that ECAP processing at a temperature of 473 K has three significant effects. First, it refines the grain size to ~0.3 ?m. Second, the high stresses imposed in ECAP lead to a fragmentation of the rod-like MgZn2 precipitates into smaller particles with significant fragmentation occurring in the first pass and additional breaking in subsequent passes. Third, there is a partial loss of the metastable ??-phase. Tensile testing at room temperature revealed a significant reduction in the ultimate tensile strength after ECAP due to the loss of the hardening ??-phase. Tensile testing at 673 K gave superplastic ductilities provided samples were pressed through a sufficient number of passes to achieve a reasonably large fraction of high-angle boundaries.
M A Cisneros - One of the best experts on this subject based on the ideXlab platform.
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effect of temperature on the tensile properties of an as Cast Aluminum Alloy a319
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: E Rincon, H F Lopez, M M Cisneros, H Mancha, M A CisnerosAbstract:Abstract The tensile properties of an as-Cast A319 Alloy were investigated as a function of temperature. It was found that the A319-Al Alloy remained inherently brittle in the temperature range of −90 °C T T > 270 °C the mode of failure shifts to being essentially ductile by the development of numerous dimples. Under these conditions the development of critical stresses at matrix/particle interfaces needed for brittle fracture no longer occurs. Apparently, at these temperatures thermally activated processes lead to significant relaxation of stress incompatibilities at particle/matrix interfaces and results in appreciable plastic deformation within the matrix.