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1
Ziolkowski, Joseph Edmund. "Modeling of an aerospace sand casting process." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-1223102-102625.
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Chen, Chien-Lung. "Evaluation of aluminum die casting defects causing casting rejection during machining." Connect to resource, 1997. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1155309911.
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Saleem, Muhammad Qaiser. "Helium Assisted Sand Casting of Aluminum Alloys." Digital WPI, 2011. https://digitalcommons.wpi.edu/etd-dissertations/204.
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Sand casting is the most widely used casting process for both ferrous and non-ferrous alloys; however, the process is marred by large grain size structures and long solidification times. The coarser microstructure has a negative effect on the mechanical properties of the cast components and the long processing time affects the overall productivity of the process. The research reported herein addresses these problems for aluminum sand castings by enhancing the rate of heat extraction from the casting by replacing air, which is typically present in the pores of the sand mold and has a relatively low thermal conductivity by helium which has a thermal conductivity that is at least five times that of air in the temperature range of interest. The effect of (1) the flow rate of helium, (2) the way in which it is introduced into the mold, and (3) the mold design on (a) the average grain size, (b) the secondary dendrite arm spacing, and (c) the room temperature tensile properties of castings is investigated and compared to their counterparts produced in a typical sand casting process. In addition, a cost analysis of the helium-assisted sand casting process is performed and an optimum set of parameters are identified. It is found that when the helium-assisted sand casting process is performed with close to the optimum parameters it produces castings that exhibit a 22 percent increase in ultimate tensile strength and a 34 percent increase in yield strength with no significant loss of ductility, no degradation in the quality of the as-cast surfaces, and no significant increase in the overall cost.
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Wu, Yaping. "Numerical analysis of direct-chill casting of aluminum ingot." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=672.
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Thesis (M.S.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains xi, 150 p. : ill. (some col.) Vita. Includes abstract. Includes bibliographical references (p. 86-89).
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Ammar, Hany. "Effet des imperfections de la coulée sur les propriétés en fatigue des alliages de fonderie aluminium silicium = Effect of casting imperfections on the fatigue properties of aluminum-silicon casting alloys /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2006. http://theses.uqac.ca.
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Tenekedjiev, Nedeltcho. "Strontium treatment of aluminum : 17% silicon casting alloys." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61774.
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Joseph, Carolyn M. "Detection of Floating Grains in DC Aluminum Casting." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/109015.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2017.Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 42-44).
Free-moving "floating" grains have been linked to macrosegregation in direct-chill (DC) aluminum castings. The presence of these grains in the sump of a solidifying ingot has been acknowledged based on measurements of cast microstructures and by recent work using a turbulent jet to suspend solute-poor grains and minimize macrosegregation.1,2 Experiments in this study were designed to sample grains from the mushy region of two ingots, one cast by the standard method and another stirred with a turbulent jet. Measurements of floating grain size, concentration, morphology, and chemical composition are reported. The observations from the standard ingot offer a point of comparison for floating grain theories and casting models. The measurements from the stirred ingot show how the turbulent jet modifies the distribution, concentration and morphology of the floating grains.
by Carolyn M. Joseph.
S.M.
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Hogan, Patrick Alan. "Prediction and Reduction of Die Soldering." Digital WPI, 2008. https://digitalcommons.wpi.edu/etd-theses/523.
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Die Soldering occurs in aluminum permanent mold casting when the cast metal bonds with the die surface and remains stuck upon ejection of the part. Eventually, this layer builds up and production must be stopped for cleaning. It was estimated in a Contech squeeze casting plant in Pierceton, IN, that 1.5% of variable overhead can be directly attributed to die soldering. Previous work at WPI has focused on developing the mechanism of how soldering occurs. This work focuses on how that knowledge can be applied in an industrial setting. The work has focused on 4 major areas: (1) Using MAGMAsoft to predict die soldering, (2) Using surface metrology to measure die soldering, (3) Documenting the total process effects of using strontium modified casting alloys. The work has resulted in: (1) Guidelines for using MAGMAsoft to predict die soldering. The results can be incorporated into the existing MAGMA die soldering module, but provide more accurate time and temperature criteria. (2) The results of the study prove that measurement of the surface of the cast part itself can be used as a method for quantifying die soldering. (3) The total process effects of Sr-modification are reported, along with suggestions for immediate use of Sr-modification at the Pierceton, IN casting plant and guidelines for using Strontium in the future.
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Turkyilmaz, Gokhan. "Processing And Assessment Of Aluminum Ceramic Fiber Reinforced Aluminum Metal Matrix Composite Parts For Automotive And Defense Applications." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610751/index.pdf.
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The aim of this study was to produce partially reinforced aluminum metal matrix
composite components by insertion casting technique and to determine the effects
of silicon content, fiber vol% and infiltration temperature on the mechanical
properties of inserts, which were the local reinforcement parts of the components.
Silicon content of alloys was selected as 7 wt% and 10 wt%. The reinforcement
material, i.e. Saffil fiber preforms, had three different fiber vol% of 20, 25 and 30
vol% respectively. The infiltration temperatures of composite specimens were fixed
as 750 °C and 800 °
C. In the first part of the thesis, physical and mechanical properties of composite specimens were determined according to the parameters of silicon content of the matrix alloy, infiltration temperature and vol% of the reinforcement phase. X-ray diffraction examination of fibers resulted as the fibers mainly composed of deltaalumina fibers and scanning electron microscopy analyses showed that fibers had planar isotropic condition for infiltration. Microstructural examination of composite specimens showed that appropriate fiber/matrix interface was created together with small amount of micro-porosities. Bending tests of the composites showed that as fiber vol% increases flexural strength of the composite increases. The highest strength obtained was 880.52 MPa from AlSi10Mg0.8 matrix alloy reinforced with 30 vol% Saffil fibers and infiltrated at 750 °
C. Hardness values were also increased by addition of Saffil fibers and the highest value was obtained as 191 HB from vertical to the fiber orientation of AlSi10Mg0.8 matrix alloy reinforced with 30 vol% Saffil fibers. Density measurement revealed that microporosities existed in the microstructure and the highest difference between the theoretical values and experimental values were observed in the composites of 30 vol% Saffil fiber reinforced ones for both AlSi7Mg0.8 and AlSi10Mg0.8 matrix alloys. In the second part of the experiments, insertion casting operation was performed. At casting temperature of 750 °
C, a good interface/component interface was obtained. Image analyses were also showed that there had been no significant fiber damage between the insert and the component.
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Capps, Johnathon. "Advancements in vacuum process molding and casting." Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Summer/master's/CAPPS_JOHNATHON_6.pdf.
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Garza-Delgado, Abelardo. "A study of casting distortion and residual stresses in die casting." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1196175848.
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Shabestari, Saeed G. "Formation of iron-bearing intermetallics in aluminum-silicon casting alloys." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28920.
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The formation of iron-bearing intermetallics in the 413 type of aluminum alloys was investigated comprehensively. Both synthetic and commercial 413 alloys were studied with iron concentrations in the range of 0.4-1.2 wt. % and manganese up to 0.5 wt.%. The effects of cooling rate during solidification and of melt chemistry on the morphology of iron intermetallic phases were determined. Image analysis was used to quantify the intermetallic size, volume fraction, and number, as a function of both melt chemistry and cooling rate. The total volume fraction of intermetallic compounds in these alloys was related to cooling rate by an exponential equation.The kinetics of both dissolution of intermetallics on melting, and of re-formation on cooling of the liquid were investigated by means of quenching experiments. Quantitative evaluation of intermetallic size and number revealed that the change in volume fraction of intermetallics in the liquid state is controlled by nucleation.
The effect of settling time and the rate of gravity segregation of intermetallic compounds in a stagnant liquid metal were investigated. It was found that, in the absence of convection, settling obeys Stokes' law with the terminal velocity reached at very short times and very close to the melt surface.
Strontium was used to modify or eliminate the iron-intermetallics. (Abstract shortened by UMI.)
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Ragel, Kamal R. "Three dimensional modeling of vertical DC casting of aluminum alloys." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84313.
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A three-dimensional mathematical model for the simulation of vertical direct chill (DC) slab casting of aluminum alloys has been developed. The model is based on the solution of the 3D time-averaged turbulent momentum (Navier-Stokes) and energy equations. The momentum equations are modified with a Darcy-type source term to simulate motion of the melt in the mushy region. The buoyancy force term is implemented in the model through the Boussinesq approximation. The low Reynolds number k-ε turbulence model of Launder and Sharma is used to calculate the Reynolds stresses and the turbulent heat fluxes. A variable heat transfer coefficient is used along the ingot surface to account for the different cooling regions. The mathematical model is qualitatively and quantitatively verified by comparing the computed results with a physical water model and a real casting experiment, respectively of independent researchers. Each of the comparisons showed a good agreement. The quantitative verification of the solidification front depths is improved when the thermal buoyancy force effect is included in the model.A parametric study has been carried on two casters of variable aspect ratio each using a different type of inlet melt distribution system. In the case of the small aspect ratio caster, the physical properties of aluminum Al-3104 are used. For this caster, the studied parameters are the casting speed, the primary cooling rate, the melt superheat and the combo-bag dimensions. Also, the effect of complete blockage of the bottom windows of the distribution bag is studied. An in-depth understanding of some behaviors of the melt flow and solidification profile in the steady state operational phase of the DC casting process is gained. For example, the roles played by the angle flow and the upward component of the vertical recirculation at the wide symmetry plane in controlling both the solidification front depth and the mushy layer thickness at the slab center are ascertained. This study has revealed the influence of the melt stream issued from the bottom window of the bag on the depth and uniformity of the solidification front. The model has successfully identified a faulty design of the short combo bag. This industrially favorite design causes what is called the reverse flow, that is, the melt from the surrounding sump enters the combo bag through the bottom window. (Abstract shortened by UMI.)
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Wu, Chang Kai. "Predicting the Response of Aluminum Casting Alloys to Heat Treatment." Digital WPI, 2012. https://digitalcommons.wpi.edu/etd-dissertations/117.
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The objective of this research was to develop and verify a mathematical model and the necessary material database that allow predicting the physical and material property changes that occur in aluminum casting alloys in response to precipitation-hardening heat treatment. The model accounts for all three steps of the typical precipitation hardening heat treatment; i.e., the solutionizing, quenching, and aging steps; and it allows predicting the local hardness and tensile strength, and the local residual stresses, distortion and dimensional changes that develop in the cast component during each step of the heat treatment process. The model uses commercially available finite element software and an extensive database that was developed specifically for the aluminum alloy under consideration - namely A356.2 casting alloy. The database includes the mechanical, physical, and thermal properties of the alloy all as functions of temperature. The model predictions were compared to measurements made on commercial cast components that were heat treated according to standard heat treatment protocols and the model predictions were found to be in good agreement with the measurements.
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Soderhjelm, Carl. "Multi-Material Metal Casting: Metallurgically Bonding Aluminum to Ferrous Inserts." Digital WPI, 2017. https://digitalcommons.wpi.edu/etd-dissertations/174.
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Properties of cast aluminum components can be improved by strategically placing ferrous inserts to locally improve properties such as wear resistance and stiffness. A cost-effective production method is to cast-in the insert using the solidification of the molten aluminum as a joining method. Metallurgically bonding between the metals could potentially improve both load and heat transfer across the interface. The metallurgical bond between the steel and the aluminum has to be strong enough to withstand stresses related to solidification, residual stresses, thermal expansion stresses, and all other stresses coupled with the use of the component. Formation of a continuous defect free bond is inhibited by the wetting behavior of aluminum and is governed by a diffusion process which requires both energy and time. Due to the diffusional nature of the bond growth in combination with post manufacturing heat treatments defects such as Kirkendall voids can form. The effect of aluminum alloying elements during liquid-solid bond formation in regards to microstructural changes and growth kinetics has been described. A timeframe for defect formation during heat treatments as well as microstructural changes has been established. The effect of low melting point coatings (zinc and tin) on the nucleation of the metallurgical bond has been studied as well the use of a titanium coating for microstructural modification. A set of guidelines for successful metallurgical bonding during multi- material metal casting has also been constructed.
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Ridgeway, Colin D. "Integrated Computational Materials Engineering (ICME) of Aluminum Solidification and Casting." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587378327014374.
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Saha, Deepak. "Novel Processing Methods and Mechanisms to Control the Cast Microstructure in Al Based Alloys - 390 and Wrought Alloys." Link to electronic thesis, 2005. http://www.wpi.edu/Pubs/ETD/Available/etd-041405-150300/.
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Demirel, Onur. "Development Of Automobile Chassis Parts Via Aluminum Extrusion And Sand Casting Technology." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614965/index.pdf.
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Due to the environmental issues related with fuel consumption and additionally passenger safety, aluminum space frame chassis is promising a big opportunity to design a lightweight structure with a high stiffness. Despite the lower stiffness and strength of aluminum in comparison to the conventional steel chassis, it can be compensated with changing thickness and design of structure by space frame geometry In this study, instead of using steel for automobile chassis, main goal is producing a space frame structure with using aluminum in an extrusion and sand casting processes and improve the stiffness. Chassis is designed according to calculations for moment of inertia, torsional and bending stiffness and in sufficient structural stiffness which can compete with steel chassis. Static finite element analysis was carried out to understand the chassis bending, torsional stiffness and fatigue behaviors. For frontal collisions, dynamic finite element analysis was also done to determine increases in the energy absorbance, specific energy absorbance and peak force for passenger safety. Aluminum profiles were produced by hot extrusion and joined with sand casting parts by TIG welding to manufacture a space frame structure. For main chassis profile, 6063 series of aluminum alloy was selected due to availability for extrusion process, weldability and having sufficient tensile strength and percent elongation and treatment response. Three point bending test was carried out to determine flexural strength. Moment of inertia calculations were done. Some parts such as side frame and shock absorber tower were produced by sand casting method. A similar composition to Silafont &ndash36 aluminum alloy was selected because of its high fluidity and good mechanical properties
despite it is a die cast alloy. Tensile, hardness and Charpy impact test were conducted to determine the mechanical characteristics of Silafont - 36 sand cast alloy. In addition to microstructure features and thermal analysis were also carried out to achieve sufficient alloy properties. Heat affected z one was investigated by hardness and tensile test to determine the mechanical properties change after welding process. In this space frame development study, A, B and C pillar parts were produced by Al &ndash
Si sand casting and T6 heat treatment then welded together by TIG welding and finally assembled on the bottom chassis frame produced by using 6063 extrudes welded by 4000 series electrodes. The space frame chassis was studied by also computer simulation to test and see critical points which must be modified during manufacturing. Besides the experimental and theoretical studies, space frame was also produced at the same time. According to the experimental results, the feasibility of the production of lightweight and solid chassis structure was achieved.
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Wei, Xiaodan. "Thermal mechanical analysis of interfacial behavior in aluminum alloy wheel casting process." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46024.
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The focus of this project is to improve the understanding of the interfacial heat transfer behavior within the Low-Pressure Die Casting (LPDC) process, which is the main manufacturing process for A356 aluminum alloy wheels, and to develop an improved methodology/expression for calculating the heat transfer across the wheel/die interface. To formulate and assess expressions for the interfacial behavior, a 2D-axisymmetric coupled thermo-mechanical model has been developed in the commercial finite element package, ABAQUS. The model was capable of predicting the thermal history, deformation and the variation of the air gap and pressure along the wheel/die interface.
The temperature predictions of the coupled thermo-mechanical model were compared with temperature measurements obtained at Canadian Auto Parts Toyota Inc obtained on a production die. A displacement measurement setup using a high temperature eddy current displacement sensor was designed and tested in a lab setting but not employed in a plant trial due timing issues.
Initially, the coupled thermo-mechanical model was run with a temperature dependent interfacial heat transfer coefficient to obtain preliminary air gap and pressure behavior at various locations. Comparisons with the thermocouple measurements suggest that the model is able to generally qualitatively, and at some locations quantitatively, predict the temperature changes from the main physical phenomena occurring during the casting process.
The preliminary air gap and pressure predictions were used to develop a temperature, gap size and pressure dependent interfacial heat transfer coefficient based on literature review. The interfacial heat transfer coefficient was implemented in the model, and was found to improve the agreement between the model predictions and measured temperatures, but was prone to numerical convergence issues.
A new methodology of incrementally changing the interfacial heat transfer coefficient has been proposed to solve the issues. The methodology was implemented in an EXCEL spreadsheet to test it and the calculated interfacial heat transfer coefficients were found to be continuous, reflecting the effects of air gap and pressure evolution. The methodology and corresponding algorithm should be further developed for use in an ABAQUS model in the future.
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Guthy, Hema Vardhan. "Evolution of the Eutectic Microstructure in Chemically Modified and Unmodified Al-Si Alloys." Digital WPI, 2002. https://digitalcommons.wpi.edu/etd-theses/191.
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Aluminum-silicon alloys are an important class of commercial non-ferrous alloys having wide ranging applications in the automotive and aerospace industries. Typical aluminum-silicon alloys have two major microstructural components, namely primary aluminum and an aluminum-silicon eutectic. While nucleation and growth of the primary aluminum in the form of dendrites have been well understood, the understanding of the evolution of the Al-Si eutectic is still incomplete. The microstructural changes caused by the addition of strontium to these alloys is another important phenomenon that still puzzles the scientific community. In this thesis, an effort has been made to understand the evolution of the Al-Si eutectic in the presence and absence of strontium through two sets of experiments: (1) Quench experiments, and (2) sessile drop experiments. The quench experiments were designed to freeze the evolution of the eutectic after various time intervals along the eutectic plateau. The sessile drop experiments were designed to study the role of surface energy in the formation of the eutectic in the presence and absence of strontium. Both experiments were conducted on high purity alloys. Using observations from these experiments, possible mechanis(s) for the evolution of the Al-Si eutectic and the effects of strontium on modifying the eutectic morphology are proposed.
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Kurtoglu, Aziz. "Aluminum Oxide And Titanium Diboride Reinforced Metal Matrix Composite And Its Mechanical Properties." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605381/index.pdf.
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This study is on the production and testing of an aluminum metal matrix composite. Metal Matrix Composites can be produced in several different ways. In this study, an aluminum matrix composite is produced by direct addition of the reinforcement ceramic into the liquid metal. The ceramic reinforcement for this process was a mixture of TiB2 and Al2O3 which was produced by means of a thermite reaction of reactants Al, B2O3 and TiO2 all in powder form with their respective stoichiometric amounts. This ceramic mixture was ground to fine powder size and then added to liquid aluminum in small percentages. After casting and taking samples of unreinforced alloy and reinforced alloys, their tensile strength and hardness as material properties were measured and compared. Another issue is the wetting of ceramic particles by molten Aluminum. The aim of the experiments in general is to find a better way to produce a composite material with desired mechanical properties.
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Rivero, Paz Ive. "The effect of key microstructure features on the machining of an aluminum-silicon casting alloy /." View online, 2010. http://ecommons.txstate.edu/engttad/1.
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Venkatasamy, Vasanth Kumar. "Analysis of in-cavity thermal and pressure characteristics in aluminum alloy die casting." Connect to this title online, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1100721824.
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Bates, William. "Casting repair and Surface Modification of Aluminum Alloys using Friction Stir Processing (FSP)." Thesis, Högskolan Väst, Avdelningen för Industriell ekonomi, Elektro- och Maskinteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-16675.
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This thesis investigates using friction stir welding to repair common surface defects found in aluminum-silicon sand castings. Wherein, the effect of welding parameters: weld RPM, weld speed, and number of weld passes, were evaluated using hardness, porosity density, welding temperature, microstructure refinement as metrics. Therefrom, the results strongly suggest friction stir welding: reduces porosity size, reduces porosity density in a specific area, increases average hardness, improves hardness uniformity, increases surface roughness, redistributes microstructure features in a manner that theoretically improves strength, and maintains a welding temperature less than 660 degrees Celsius.
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Duan, Jianglan. "Development of a numerical optimization methodology for the aluminum alloy wheel casting process." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57699.
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Aluminum alloy wheel manufacturers face on-going challenges to produce high quality wheels and increase production rates. Improvements are generally realized by modifying the wheel and die designs and continually improving the manufacturing processes. Conventionally, these improvements have been realized by trial-and-error, building on past practice or experience. This approach typically results in long design lead times, high scrap rates and less than optimal production rates. The work presented in this study seeks to reduce the reliance on trial-and-error techniques by developing a new methodology to optimize the wheel casting process through the combination of a casting process model and open-source numerical optimization algorithms. The casting process model utilized in this method was developed in the commercial finite element package Abaqus™ and was validated through plant trials. An open source optimization module Python Scipy.optimize has been employed to perform the optimization. The work focuses on optimizing the cooling conditions in a low-pressure die-casting (LPDC) process used to produce automotive wheels. Specifically cooling channel timing was selected because of the critical role heat extraction plays on casting quality, both in terms of dendrite cell size and the formation and growth of porosities. The methodology was first developed with a series of test problems ending with an L-shaped geometry that employed the major features of the wheel casting process. The most suitable approach, based on the test problems, was then applied to the optimization of a 2-D axisymmetric prototype wheel die structure. The outcome revealed that numerical optimization coupled with a state-of-the-art process model has the potential to dramatically improve the method of determining cooling channel timings while also improving the product quality and process performance. The utility of the optimization methodology was found to depend on the accuracy of the casting process model. Significant challenges remain before widespread implementation of this methodology can occur in industry. Possible directions for further developments have been identified. In summary, this study represents one of the initial applications of a numerical optimization methodology to wheel casting, and that with further development; it will become an effective tool for process and die design optimization.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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Dewhirst, Brian A. "Optimization of the heat treatment of semi solid processed A356 aluminum alloy." Link to electronic thesis, 2005. http://www.wpi.edu/Pubs/ETD/Available/etd-111705-111503/.
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Thesis (M.S.)--Worcester Polytechnic Institute.Keywords: microstructure; casting; Fluid Bed; Quality Index; Aluminum; A356; heat treatment; SSM; Semi Solid Metal Includes bibliographical references. (p.105-106)
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Nemeth, Bill. "Casting conditions and iron variant effects on the subsequent nucleation of Al₂₀Cu₂Mn₃ dispersoid phase in Al-4Cu-0.4Mn-0.2Si alloys." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/20805.
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Dabayeh, Ashraf A. "The role of casting defects in the fatigue behavior of notched cast aluminum alloys." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0013/NQ32821.pdf.
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Tu, Zhiqiang. "Fabrication and Mechanical Properties of Carbon Fiber Reinforced Aluminum Matrix Composites by Squeeze Casting." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40523.
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Rapid modern technological changes and improvements bring great motivations in advanced material designs and fabrications. In this context, metal matrix composites, as an emerging material category, have undergone great developments over the past 50 years. Their primary applications, such as automotive, aerospace and military industries, require materials with increasingly strict specifications, especially high stiffness, lightweight and superior strength. For these advanced applications, carbon fiber reinforced aluminum matrix composites have proven their enormous potential where outstanding machinability, engineering reliability and economy efficiency are vital priorities.
To contribute in the understanding and development of carbon fiber reinforced aluminum matrix composites, this study focuses on composite fabrication, mechanical testing and physical property modelling. The composites are fabricated by squeeze casting. Plain weave carbon fiber (AS4 Hexcel) is used as reinforcement, while aluminum alloy 6061 is used as matrix. The improvement of the squeeze casting fabrication process is focused on reducing leakage while combining thermal expansion pressure with post-processing pressing. Three different fiber volume fractions are investigated to achieve optimum mechanical properties. Piston-on-ring (POR) bend tests are used to measure the biaxial flexural stiffness and fracture strength on disc samples. The stress-strain curves and fracture surfaces reveal the effect of fiber-matrix interface bonding on composite bend behaviour. The composites achieved up to 11.6%, 248.3% and 90.1% increase in flexural modulus, strain hardening modulus and yield strength as compared with the unreinforced aluminum alloy control group, respectively. Analytical modelling and finite element modelling are used to comparatively characterise and verify the composite effective flexural modulus and strength. Specifically, they allowed
iii
evaluating how far the experimental results deviate from idealized assumptions of the models, which provides an insight into the composite sample quality, particularly at fiber-matrix interfaces. Overall, the models agree well with experimental results in identifying an improvement in flexural modulus up to a carbon fiber volume fraction of 4.81vol%. However, beyond a fiber content of 3.74vol%, there is risk of deterioration of mechanical properties, particularly the strength. This is because higher carbon fiber volume fractions restrict the infiltration and wetting of carbon fibre by the liquid, potentially leading to poor fiber-matrix interface bonding. It is shown that higher thermal expansion pressures and subsequent post-processing pressing can overcome this challenge at higher carbon fiber volume contents by reducing fiber-aluminum contact angle, improving infiltration, reducing defects such as porosity, and overall improving fiber-matrix bonding.
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Papai, Jonathan Pearson. "Contact heat transfer coefficients in aluminum alloy die casting: an experimental and numerical investigation/." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu148784937729536.
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Sivertsen, Halses Sebastian. "Die life prediction using High Pressure Die Casting simulations." Thesis, Tekniska Högskolan, Jönköping University, JTH, Material och tillverkning, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-50031.
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Global trends in automotive industry for weight reduction drives an interest for casting of structural aluminum parts. High pressure die casting (HPDC) is chosen for this purpose since it enables manufacturing of large series parts where complexity and repeatability is demanded. Aluminum alloys have hence been developed through the years to obtain suitable mechanical properties for high strength parts. These alloys have been investigated to predict the types of potential failure mechanisms during HPDC in order to determine die life through simulations. Die life prediction was performed through simulations in MAGMAsoft 5.4 with the help of a die life module, which is based on thermal stresses generated in the die material during casting cycles. Fatigue data at elevated temperature obtained from literature review of AISI H11 tool steel was complemented to the Wöhler curve in the software database. Comparison of two aluminum alloys showed that chemical composition had a major influence on die life. Chemical composition had a direct impact on solidification time and with longer solidification time, the thermal load on the die increased. Since the stress range on the die is temperature dependent, the ability of heat transfer over time proved to be critical for die life results. The most crucial process parameter to achieve a longer die life was constant cooling by tempering channels, due to their high potential to remove heat. Tempering channels and die spray also prevent the die from exceeding a critical temperature resulting in soldering formation. Mold erosion was consistently observed in the same location for all simulations.
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Campo, Kaio Niitsu 1988. "Uso da extrusão em canal angular na produção da liga A356 para tixoconformação." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265929.
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Orientador: Eugênio José ZoquiDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Este trabalho investigou o uso da extrusão em canal angular (ECA) na produção de matéria-prima para tixoconformação visando à obtenção de uma rota simples e eficiente na formação de microestruturas globulares. Para tanto, uma liga de alumínio A356 foi submetida a um único passe ECA e, em seguida, reaquecida ao estado semissólido a 580°C. Dessa forma, pôde-se determinar a evolução morfológica e os mecanismos envolvidos na formação da pasta metálica, a influência do tratamento isotérmico na evolução microestrutural no estado semissólido, o comportamento de deformação durante a compressão a quente e o comportamento mecânico em tração do material tixoconformado. Os resultados indicaram que apenas um passe ECA foi suficiente para gerar uma pasta metálica refinada e globular apenas com o reaquecimento da matéria-prima. O engrossamento da microestrutura durante o tratamento isotérmico foi controlado principalmente pelo mecanismo de Ostwald ripening, fato comprovado pelo baixo valor da constante taxa de engrossamento K, o que mostrou a estabilidade dessa pasta no estado semissólido. As amostras exibiram comportamento tixotrópico típico com baixos valores de viscosidade aparente, na faixa de 10^2 a 10^3 Pa.s para as taxas de cisalhamento testadas. Por fim, as amostras tixoconformadas apresentaram valores de ductilidade e resistência à tração superiores aos das amostras fundidas e deformadas por um passe ECA
Abstract: This work investigated the use of equal channel angular pressing (ECAP) for the production of raw materials for thixoforming in order to obtain a simple and efficient processing route to generate globular microstructures. Therefore, an A356 aluminum alloy was processed by one ECAP pass, and then reheated to the semisolid state up to 580°C. Thus, it was possible to determine the morphological evolution and mechanisms involved in the formation of the semisolid slurry, the influence of isothermal treatment on microstructural evolution in the semisolid state, the deformation behavior during hot compression tests and the tensile properties of the thixoformed material. The results indicated that a single ECAP pass was sufficient to promote a refined and globular semisolid slurry. Microstructure coarsening during the isothermal treatment was mainly controlled by Ostwald ripening, which was verified by the low rate constant K, showing the stability of the reheated material in the semisolid state. The samples exhibited typical thixotropic behavior with low apparent viscosity ranging from 10^2 to 10^3 Pa.s over the applied shear rates. Finally, the thixoformed samples exhibited values of ductility and tensile strength superior to the as-cast and ECAPed samples
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
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Forté, Martin. "Modélisation de l'écoulement de l'aluminium semi-solide dans le moulage sous pression /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2006. http://theses.uqac.ca.
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Thèse (M.Eng.) -- Université du Québec à Chicoutimi, 2006.La p. de t. porte en outre: Mémoire présenté à l'Université du Québec à Chicoutimi comme exigence partielle de la maîtrise en génie. CaQCU Bibliogr.: f. [142-145]. Document électronique également accessible en format PDF. CaQCU
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Keles, Ozgur. "Production And Characterization Of Alumina Fiber Reinforced Squeeze Cast Aluminum Alloy Matrix Composites." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609726/index.pdf.
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The aim of the present study was to investigate the effects of different levels of Saffil alumina fiber addition, magnesium content in aluminum alloy matrix and casting temperature on the mechanical behavior, microstructure and physical properties of short fiber reinforced aluminum matrix composites. The main alloying element silicon was kept constant at 10 wt%. Magnesium contents were selected as 0.3 wt% and 1 wt%. Saffil alumina fiber preforms varied from 10 to 30 vol%. The casting temperatures were fixed at 750 °C and 800 °
C. Micro porosity was present at the fiber-fiber interactions. Closed porosity of the composites increased when fiber vol% increased, however, variation in casting temperature and magnesium content in matrix did not have influence on porosity. Hardness of the composites was enhanced with increasing fiber vol%, magnesium content in matrix and decreasing casting temperature. Alignment of fibers within the composite had an influence on hardness
when fibers were aligned perpendicular to the surface, composites exhibited higher hardness. The highest hardness values obtained from surfaces parallel and vertical to fiber orientation were 155.6 Brinell hardness and 180.2 Brinell hardness for AlSi10Mg1 matrix 30 vol% alumina fiber reinforced composite cast at 800 °
C and at 750 °
C, respectively. 30 vol% Saffil alumina fiber reinforced AlSi10Mg0.3 matrix composite cast at 750 °
C showed the highest flexural strength which is 548 MPa. Critical fiber content was found as 20 vol% for all composites.
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Nandakumar, Varun. "Process and Tool Design for the High Integrity Die Casting of Aluminum and Magnesium Alloys." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1409032627.
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Binney, Matthew N. "Porosity reduction in high pressure die casting through the use of squeeze pins /." [St. Lucia, Qld.], 2006. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19810.pdf.
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王培義. "Extrusion casting of aluminum alloys." Thesis, 1989. http://ndltd.ncl.edu.tw/handle/61781702036910042467.
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羅玉林. "Squeeze casting of aluminum alloys." Thesis, 1987. http://ndltd.ncl.edu.tw/handle/88156529009138003987.
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(10729758), Clayton M. Kibbey. "A380 Aluminum Hot Chamber Die Casting." Thesis, 2021.
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A hot chamber die casting machine designed for zinc was donated to Purdue University. This
machine was slated for retrofit of components necessary for aluminum hot chamber die casting.
Existing components designed for zinc, mainly H-13 and cast iron, do not have the necessary
service life to economically produce castings due to chemical attack on machine components
from molten aluminum. Multiple systems were redesigned, including the pot, plunger,
gooseneck, furnace, and cooling lines. All components were upgraded to allow for the higher
service temperatures needed for molten aluminum, along with a niobium gooseneck and anviloy
nozzle to resist chemical attack of injection components. Once design and retrofitting were
complete aluminum alloy A380 was used in conjunction with a niobium gooseneck design to
create tensile bars. These tensile bars were subsequently tested and mechanical properties
evaluated.
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Yu, Chia-Chieh, and 余家杰. "ANALYSIS OF CASTING PROCESS OF ALUMINUM WHEEL." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/90338218672705307073.
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碩士元智大學
機械工程學系
91
Aluminum disc wheels intended for normal use on passenger cars are commonly produced by gravity casting. If the cooling process and initial temperature of mold are not well controlled, shrinkage cavity will occur after solidification, which might cause leakage problems to the disc wheel. This thesis simulated the casting process by computer simulation, and a Shrinkage Index (SI) is defined using the phenomenon of liquid entrapped. This thesis then discussed the influence of cooling process, initial temperature, and geometry of the wheel on SI after the mold temperature has converged. The relationship between SI and the percentage of wheels that have leakage in real test was discussed. We can use the simulation process and SI to predict the quality of the casting wheel and to find the optimal parameters.
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Yang, Chao Wei, and 楊朝維. "Numerical Simulation of Aluminum Die-casting Process." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/fbayuk.
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碩士正修科技大學
機電工程研究所
105
In the manufacturing process of die casting, the filling pattern of alloy liquid is featured with fast flow and short coagulation time might lead to the presence of cavity, shrinkage pore and inclusion inside the product, thus invoking the poor air tightness and mechanical property decline. This project intends to employ the die casting analysis software Procast to perform the modelling, process analysis and quality prediction for the massive products of the cooperative company. The stringent requirements include boreholes rate of valves smaller than 1.0% of motor housing and carburetor case, etc. With the analysis outcomes provided by Procast, such as the microstructural module, semi-solid pressure casting module, and aluminum alloy database module, the precise suggestions for improving the mechanical properties and manufacture process parameters can be made. Next, the manufacture bottlenecks of different products will be tackled as well, such as (1) the effect of silicon amount in the aluminum alloy liquid on the fluidity and microstructural variation of the large-scale discoidal die casting pieces; (2) the overload cavity due to the bore inside the servo-motor case of different size of vehicle steering gear. With the software, the common problems faced in the exploitation of products, such as pouring system, residue removal system, inner pouring gate, overflow tank, air vent, the material selection of pressure casting and so on, can be solved by offering better solutions. In addition, by proper assumption and setting of software, the manufacture parameters like die injection speed, filling time, preheating temperature of mold and supercharging ratio can be improved by using the outcomes of simulation. The execution period of this project is one year. We have been conducted more than 10 exchanges with the company's R & D. We completed the software analysis, product defect forecast and provide improvement proposals for the products developed by the company to effectively enhance the quality of their products.
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Ortega, Pelayo Rosa Elia. "Direct Chill and Fusion Casting of Aluminum Alloys." Thesis, 2012. http://hdl.handle.net/10012/7153.
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Novelis Inc. recently developed and patented a unique Direct Chill (DC) casting process known as Fusion Novelis Technology. In this process a chill bar is inserted into the DC casting mould which permits for the first time the co-casting of laminate of clad ingots. These ingots can then be rolled down
into clad sheet and offer distinct advantages over traditional aluminum clad sheet processing routes (i.e. brazing and roll bonding).
The research presented in this Master’s Thesis was done as part of a larger collaborative research and development project with Novelis Inc. The main objective of this research was to investigate the
Novelis Fusion Technology and understand it from a scientific viewpoint. The research has been multi faceted and has included: the creation of a thermal fluid model using the commercial software
package CFD to model the first the DC and then Fusion casting process, as well as the design and testing of an experimental DC and Fusion caster at the Novelis Global Technology Centre (NGTC) in Kingston, Ontario. This MASc research has been focused on performing both traditional DC (for AA6111, AA3004 and AA4045) and novel Fusion (AA3004/AA4045) casting experiments. First the series of DC casting experiments was performed. During the experiments two arrays of 5 thermocouples were embedded in the ingot during the cast to capture the thermal history of the ingot. Melt poisoning with a zinc rich alloy was also performed as an independent method of determining the
sump depth and shape. Other temperature measurements during the experiment (i.e. alloy superheat, mould temperature, cooling water temperature) were done to gather meaningful data for model validation. A series of Fusion casting experiments was performed after the DC casting trials. Three successful Fusion casting trials were performed at NGTC using a lab scale caster with a 152 mm × 381 mm rectangular mould divided in half by a water cooled copper chill bar. For the Fusion casting
experiments the AA3003-Core/AA4045-Clad alloy system was chosen since this alloy system has already been commercially produced using this novel technology. In addition to embedded thermocouples in the Fusion cast ingot, and other temperature measurements as for the DC casting experiments, temperature measurements of the chill bar were performed to gather information for model validation. The effect of melt poisoning as the interface of the composite ingot forms was unknown, so only the core of one experimental ingot was poisoned; this gave enough information about
the depth and asymmetrical shape of the AA3003-Core sump. The Fusion cast ingots were characterized (both optically and using SEM techniques) at four distinct locations across the width of the ingot, consistent with different thermal histories at the interface and regions where good and poor
interfaces were found in the solidified ingot. No clear correlation between thermal history and the quality of the interface could be found indicating that the interface formation during Fusion casting is extremely complicated and other factors such as oxide formation and wetting mechanisms of the
AA4045 on the AA3004 need to be understood to gain a more in depth understanding of the conditions necessary to form a defect free interface. Comparisons of the measured thermal histories and sump depth and shape measurements to the model predictions were excellent.
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Mo, Hsieh Kai, and 謝楷模. "Casting Simulation Analyses of A390 Aluminum Brake Shoe." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/25923705432499927949.
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碩士大葉大學
機械工程研究所碩士班
93
The A356 aluminium alloy was used on the casting of the brake shoe in the near years, but, the braking action was apt to cause the brake shoe to increase its body size because of its higher thermal expansion character of A356 alloy. The phenomenon would induce the brake lining to contact the brake drum abnormally and to decrease the braking efficiency. The A390 aluminium alloy with low coefficient of expansion can then be used to cast the brake shoe and thus to solve this problem. This research is aimed at evaluating how to cast the A390 aluminum alloy brake shoe by the CO2 sand mold method, utilizing the computer-aided engineering (CAE) simulation software FLOW-3D to study the influences of gating system designs on the A390 alloy brake shoe, and to analyze the flow of filling and the solidification of brake shoe castings. In addition, the simulations are also conducted and expected to achieve the optimum design of gating and riser systems for the A390 alloy brake shoe, and the X-ray examinations for the practical castings poured are carried out to evaluate the validity of FLOW-3D simulations. The criteria of predicting the defects produced in castings which are built in the software FLOW-3D, including the solidification fraction, solidification time, solidification gradient, solidus velocity and Niyama porosity index were used to determine the gating system designs, and to find the position of the shrinkage in the brake shoe castings. The results of this study indicate that the gating system with design of the sprue well can alleviate the flowing impact of aluminum melt falling from the inlet of sprue to the runner. While the design of bilateral R corners joining the runner and the ingate can reduce the flowing velocity at the ingate. Besides, the non-pressurized gating system with 1:4:4 gating ratio can effectively control the velocity at the ingate and prevent the turbulence of melt flow compared to the other gating systems with gating ratio(1:2:2, 1:2:3 and 1:3:3). The practical castings show that the shrinkage defects occurred are in accordance with the results of simulation. Finally, the casting designs by the FLOW-3D would improve the quality of A390 alloy brake shoe castings.
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Chen, Po-Chen, and 陳柏辰. "Optimal Analysis of A390 Aluminum Automobile Piston Casting." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/80526583166623459238.
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碩士大葉大學
車輛工程學系碩士班
92
The goal of this study was to understand the solidification and flow phenomena of A390 aluminum alloy automobile piston casting, under the computer-aided designing simulation by the computer-aided engineering (CAE) software. The CAE simulation was also determined to get the optimal casting design of piston, and the real castings were done to estimate the reliability of CAE simulation. The experimental results indicate that the non-pressurized gating system with cylindrical runner can effectively control the ingate velocity and reduce the turbulence of flow when compared to the other designs. Besides, the better ingate should be arranged at the side of piston skirt. The top riser set on the piston casting had the best feeding result. The design of chill on the piston casting with and without riser whether it is top or side, the feeding of shrinkage could not be successful and the defects also occurred inside the piston casting. The yield was changed from 78 percents to 91 percents by way of optimization design and simulation of riser on the piston casting, and the simulation results also revealed the non-pressurized gating system with the cylindrical runner and top riser design has the better yield then the other system design. Finally, the casting design of the A390 aluminum alloy automobile piston casting would be certainly evaluated by the CAE software.
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CHIANG, TSO CHUNG, and 蔣作群. "The reaserch of casting and anodizing for aluminum alloy." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/08240296473611572335.
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碩士國立中央大學
機械工程學系
85
AbstractThe purpose of the research is to improve the capability of casting ,welding and coloring anodized aluminum of two different materials , such as Al-Mg 514 cast alloy aluminum and Al-Zn-Mg 7005 extrusion aluminum. Since casting a 514 alloy thin rectangular test plate (250㎜×120㎜×4 ㎜)for welding was not easy , the author adopted four methods for casting and did many tests to solve it. Subsequently the property of 514 alloy was promoted by using various homogenization treatments and adding grain refiner , degassing and altering cast conditions , controlling the flow rate of melt alloy to reduce the phenomenon of shrinkage and hot tearing and enhance the mechanical properties of 514 alloy . The suitable cast conditions are recommended：(1)the temperature of melted aluminum alloy be controlled in the range from 770℃to 810℃(2) the temperature of mold be controlled in the range from 350℃to 370℃.The influence of adding alloy element and altering homogenization treating temperature was observed by means of Optical Microscope(OM), Scanning Electron Microscope(SEM), and Multiple tensile test(MTS).With altering various homogenization temperatures and adding alloy Al-Ti-B refiners and zirconium alloy elements, the results showed that mechanical properties of 514 alloy could be improved effectively . For 514 alloy ,higher homogenization temperature (450℃~490℃)was better than lower homogenization temperature (410℃~430℃). In observing microstructure of 514 alloy , it was interesting to find that the higher homogenization temperature was , the lower the eutectic phase in microstructure was , and the refiner in microstructure region observed was.In the mean time , adding the Al-Ti-B refiners and Zr adequately ,the tensile strength and elongation of the specimens will be excellent .The SEM fractograph inspections of tension failure areas were also applied to check the fracture morphology , which indicated that the fracture was of a typical ductile fracture .Choosing a proper filler , either 4043, 5183, 5356 , or so on , to weld two different materials was very important . After comparing the results of various welded specimens , it was found that the 5356 filler worked better than the others in coloring match if theoperating conditions were in the range from 134 to 156 amp and from 13 to 14.5v.Finally , to make sulfuring acid anodizing aluminum have excellent corrosion and wear resistance , it was oxide coated in the following conditions : (1)the concentration of sulfuric acid is 15％(165g/l) , (2) the operating temperature is 17℃, and (3) the operating time is 50 min.
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LIN, GUAN-YI, and 林冠億. "Application of CAE in Aluminum Alloy Tilt Gravity Casting." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/h89y4x.
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碩士逢甲大學
機械與電腦輔助工程學系
106
The objective of this research is to evaluate the effectiveness of gating design and misrun problem caused by back pressure of the A356 aluminum alloy tilt gravity casting vent using the foundry CAE software, ProCAST. The metallographic microstructure and hardness variation of A356 aluminum alloy casting through melt treatment to heat treatment are also evaluated. The simulation result shown that unpressurized gating system with gating ratio of “1:1.7:3.52” has a lower flow speed than “1:1.7:1.13”. Flow speed decreased about 18%. The molten aluminum flow gets steady when pouring. The simulation result is in good agreement with the actual result when “back pressure” is included in the simulation. The simulation showed that increasing vent area will help to solve the misrun problem. The correction value of “back pressure” is 0.067atm in this simulation result. The metallographic microstructure results of the casting at each process shown that ingot has a partial effect of modification and refinement when contenting 0.025% Sr and 0.025% Ti. After modification treatment and refinement treatment, the refinement effect of eutectic silicon and grain size were increased. The hardness of casting had a great promote after T4 heat-treatment and T6 heat-treatment. The CAE simulation method saved 63% of time and 40% of cost when compared with the tradition “Trail-and-Error” method.
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(7041476), Mohamadrusydi B. Mohamadyasin. "DEVELOPMENT OF HIGH DUCTILITY ALUMINUM ALLOYS FOR DIE CASTING." Thesis, 2019.
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Aluminum-Silicon (Al-Si) alloys are often preferred in the die casting industry due to excellent castability, high strength, corrosion resistance and low cost. Commonly, iron (Fe) is alloyed with the alloys to prevent die soldering. However, the addition of Fe in most of Al-Si alloys leads to formation of the intermetallic β-AlFeSi. The β-AlFeSi is harmful to the alloy structural integrity due to its needle-like morphology that creates stress concentration at the microscopic level. The phase presence is unfavorable to the mechanical properties and significantly reduces the elongation of the alloys. This research attempted to find viable way to control the morphology and formation of the β-AlFeSi phase.
Thermodynamic simulations were done to investigate the sequence of intermetallic formation and other phases at different alloy compositions. The analysis of solidification paths of different alloys provided the correlation between the phase formation sequence and the fraction of the β-AlFeSi phase. The analysis also identified the feasible region of alloy design for minimizing the β-AlFeSi formation. Based on the thermodynamics simulation analysis, five alloys of different compositions were designed to validate the finding of the simulation.
The tensile test results of the alloys indicated that lowering the Fe content increases the elongation of the alloy. The results also showed that elongation was reduced with the increase of Si level due to the formation of eutectic Silicon. The change of both Fe and Mn did not significantly affect the mechanical property of the alloy when the ratio of Fe to Mn was constant. Microscopic analysis showed that lowering the Fe level had effectively altered the morphology of the β-AlFeSi needle like structure. The β-AlFeSi was found to be smaller in terms of size when Fe is lower, subsequently reducing the probability of β-AlFeSi phase to be stress riser and crack initiation.
The influence of heat treatment to the mechanical property of the alloys was also studied. The mechanical result on the heat-treated samples indicated that heat treatment is a viable method to improve the elongation property of the alloy. Microscopic observations showed that the β-AlFeSi phase was broken into shorter structures over the solution heat treatment process, resulting in better elongation.
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Kuan, Chung-Hao, and 關中皓. "Studies on Squeeze Casting and Gravity Casting in Gas Tungsten Arc Welding of A356 Aluminum Alloy." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/39512267594439091470.
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碩士國立中央大學
機械工程學系
85
A356 aluminum alloy of the squeeze castings and gravity castings were fusion welded with the gas tungsten arc welding process.The effects of gas flow rates,T6 heat treatment, and the type of filler metal were investigated under different welding conditions. The appearance of the welded surface under anodic treatment was also compared and analyzed. It was found that the gas flow rates greatly influenced the weld porosity and the evaporation of low boiling point alloy element (such as Mg).The resulting properties of the welding are caused by both the filler metal composition and the microstructure in the fusion zone and heat-affected zone. The result of these experiments indicated that:1.Increasing shielding gas flow rates,above 20L/ min.,was reduced weld porosity and inhibited the evaporation of magnesium.2.The extent of heat-affected zone was widened in welding under T6 heat treatment. It also concerned about hardness profile,anodic coating and grain size.3.The more content of silicon in aluminum alloy castings resulted a gray colorof appearance which under anodic treatment.
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Ng, Harry. "Direct Chill Casting of Aluminum Alloys: Experimental Methods and Design." Thesis, 2011. http://hdl.handle.net/10012/5749.
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Novelis Global Technology Centre (NGTC) in Kingston, Ontario have been developing a relatively new technology known as Novelis Fusion™ Technology, which is a new variant of the traditional direct chill (DC) casting process that allows co-casting of multi-layered composite aluminum alloy ingots. One of the first steps in this development program is to create a mathematical model of conventional DC casting and validate it through experimentation before proceeding to the next step of modeling, designing, testing, and experimenting with the co casting process. The focus of this document is on the design of the experiments, measurement technique, and analysis of the experimental results to be used to validate the models for conventional DC casting. A series of experiments was conducted using a lab scale caster using a 95 mm × 227 mm rectangular mould available at the Novelis Global Technology Centre in Kingston, Ontario. AA3003, AA6111, and AA4045 aluminum alloys were chosen for this study since these aluminum alloys are commonly used in clad products.
Two series of experiments were performed to investigate the effect of casting parameters on the solidification and cooling of the ingots such as casting speed, water flow rate, and the superheat of the molten aluminum. A set of seven thermocouples were embedded in the ingot during the cast to capture the thermal history of the ingot. Melt poisoning with a zinc rich alloy was also performed as an independent method of determining the sump depth and shape.
Experienced gained from the first series of experiments allowed improvements to be made to the experiment design for the second series of experiments. Thermocouples must be supported so they are not pushed out of position by the jet of molten aluminum entering the mould. Grounded thermocouples of at least 1.5 mm in diameter were recommended to survive the high temperatures of the molten aluminum. Knowledge gained from the experiments of the conventional DC caster allowed design and development of an experimental co-caster mould that will be useful for future research at NGTC.
Melt poisoning and thermocouples were complementary measurement methods that should be used together. In all three alloys, the liquidus sump profile generated by the thermocouple implants correlated well with the etched sumps of the melt poisoned ingots. Primary and secondary water flow rates beyond 1.79 L/s and increasing the superheat by 30°C did not have significant effect of the cooling rate with solidified ingots, but all casting experiments showed that the thermal histories and sump profiles were very sensitive to the casting speed. The sump depth increased with increasing casting speed in all casting experiments. The sump depth increased directly proportionally to the Péclet number and the sump depth could be predicted using a linear regression model by calculating the Péclet number. The formation of remelting bands were seen in the surface of the AA3003 and AA4045 ingots, but were not apparent in the AA6111 ingots. A fast Fourier transform performed on the data obtained from the thermocouples that were inserted in the mould wall showed that remelting occurred at regular intervals and that the frequency increased with casting speed. The thermocouples in the mould also indicated that AA6111 had a higher rate of heat transfer than AA3003 or AA4045. The AA6111 ingots had a higher rate of heat transfer in the mould than for the other alloys. This was evidence that there was a smaller air gap formation between the ingot and the mould in AA6111.
This research on the effects of casting parameters on DC cast ingots made using the three alloys, AA3003, AA6111, and AA4045, is beneficial in the development of a design of an experimental lab-scale co-caster for validation of a computational fluid dynamics (CFD) model of the Fusion™ Technology process.
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Song, Ming-An, and 宋敏安. "Study on the Preparation of Porous Aluminum by Die Casting." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/73938846652249658549.
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碩士國立清華大學
化學工程學系
89
The preparation of porous aluminum by die casting was investigated in this work, including both the 〝lost foam 〞method and the〝ceramic ball preform 〞method. In the lost foam die casting method, we utilized the swelling phenomenon caused by soaking the polymer foam in a proper organic solution to increase the ligament thickness and its porosity. As a result, the ligament thickness and porosity of finished products can be easily tailored. Using different polymer foams from various suppliers, we can make porous aluminums whose ligament thickness is in the range of 0.117∼0.458mm and porosity about 90∼95%. In the ceramic ball preform method, we found a special formula（weight ratio of Al2O3：bentonite：HPMC：water：PVA is 100：1：2：48.3：2.4） for making ceramic balls with sufficient strength to survive the casting procedures. These ceramic balls of several mm in size, can be easily removed from the finished products by high pressure water after casting. One of the ingenuity of this procedure lies in the fact that these ceramic balls are soft and deformable at room temperature. For this reason, we can apply pressure to increase the compactness of the packed bed made of these ceramic balls. As a result, the porosity the finished products can be substantially increased. On the other hand, the uniformity of the product can be improved if regular packing technique was employed rather than the random packing method. On the average, the porosity of the product is in the range of 80∼89%.