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Numerical microstructure prediction for an aluminium casting and its experimental validation  [PDF]
Unterreiter Guenter,Ludwig Andreas,Wu Menghuai
China Foundry , 2011,
Abstract: Virtual manufacturing based on through-process modelling becomes an evolving research area which aims at integrating diverse simulation tools to realize computer-aided design, analysis, prototyping and manufacturing. Numerical prediction of the as-cast microstructure is an initial and critical step in the whole through-process modelling chain for engineering components. A commercial software package with the capability of calculating important microstructure features for aluminium alloys is used to simulate a G-AlSi7MgCu0.5 laboratory casting. The simulated microstructure, namely grain size, secondary dendrite arm spacing and diverse phase fractions are verified experimentally. Correspondence and discrepancies are reported and discussed.
Casting of Brake Disc and Impeller from Aluminium Scrap Using Silica Sand  [cached]
Matthew S. ABOLARIN,Oluwafemi A. OLUGBOJI,Oladeji A. OGUNWOLE
Leonardo Electronic Journal of Practices and Technologies , 2007,
Abstract: The impeller blade and the brake disc were produced using sand casting method. Wooden patterns of the two castings were constructed incorporating the necessary allowances. Green and moulding technique utilizing locally available materials were used for preparing the moulds. Aluminium scraps were used as the casting material. Melting of the Aluminium scraps was obtained using a crucible furnace and finally pouring the molten metal into the sand mould to obtain the impeller and the brake disc.After fettling and cleaning, the two casting were found to be good. The casting yield was found to be 73.59% for the impeller blade and 85.1% for the brake disc which indicate that sound casting was achieved.
Stereometry specification and properties of anodization surface of casting aluminium alloys  [PDF]
J. Konieczny,K. Labisz,J. Wieczorek,L.A. Dobrzański
Archives of Materials Science and Engineering , 2008,
Abstract: Purpose: The aim of the work is presents the influence of casting method and anodic treatment parameters on properties, thickness and structure of an anodic layer formed on aluminium casting alloys.Design/methodology/approach: Investigations were carried out on the laser profile measurement gauge MicroProf from company FRT, abrasive wear test was made with using ABR-8251 equipment delivered by TCD Teknologi ApS and microstructure investigations were made with using a light microscope equipped with an electronic camera configured with a computer on two casting aluminium alloys which both were founding by pressure die casting and gravity casting.Findings: The researches included analyze of the influence of chemical composition, geometry, roughness and abrasive wear resistant of anodic layer obtained on aluminium casts.Research limitations/implications: Contributes to research on anodic layer for aluminium casting alloys.Practical implications: Conducted investigations lay out the areas of later researches, especially in the direction of the possible, next optimization anodization process of aluminium casting alloys, e.g. in the range of raising resistance on corrosion.Originality/value: The range of possible applications increases for example as materials on working building constructions, elements in electronics and construction parts in air and motorization industry in the aggressive environment.
Metal head - dependent HTC in sand casting simulation of aluminium alloys  [PDF]
G.S. Cellini,L. Tomesani
Journal of Achievements in Materials and Manufacturing Engineering , 2008,
Abstract: Purpose: In order to obtain reliable sand casting products, it is essential that the temperature distribution within the alloy during cooling is accurately known at each point by FEM simulation. This requires a great precision in setting the Heat Transfer Coefficients (HTC) at the boundaries. In particular for castings of big size, chills are frequently at different heights, so that remarkable differences arise from the metal head effect.Design/methodology/approach: An A356 alloy was cast and cooled. The castings were mono-directionally solidified in a experimental equipment modified to accept a controlled variable metal-head. HTC were evaluated in a side arm, where a chill end ensured a dominant unidirectional heat flow during cooling. At the end of a square horizontal channel, an aluminium chill of the same section and 60 mm in depth determined nearly one-dimensional cooling conditions.Findings: The evolution of heat transfer coefficient (HTC) in the sand casting of A357 aluminum alloy against aluminum chills is evaluated with different metal heads in order to study the effect of pressure on the HTC. Inverse modeling techniques based on Beck’s analysis were used to determine the experimental evolution of HTC as a function of time, casting temperature and chill temperature. The HTC evolution at the casting-chill boundary is then described as a function of local parameters such as casting-chill interface pressure (as long as they are in contact) and interface gap (when solidification shrinkage occurs and the casting detaches from the chill).Practical implications: Finally, the experiments are reconstructed by means of coupled thermal-stress numerical analyses and the predicted cooling curves are fitted to the experimental ones by adjusting model parameters. As a result, the best parameters for describing the HTC evolution are found, thus allowing to extrapolate any possible HTC behavior on chills at different heights for the same casting.Originality/value: Some transient interface pressure can develop between casting and chill, the effect being negligible in HTC evaluation with the aim to precisely predict the cooling evolution inside the casting.
Microstructure and mechanical properties of NZ30K alloy by semi-continuous direct chill and sand mould casting processes  [PDF]
Zheng Xingwei,Dong Jie,Liu Wencai
China Foundry , 2011,
Abstract: The Mg-3.0Nd-0.2Zn-0.4Zr (NZ30K) alloys were prepared by direct-chill casting (DCC) and sand mould casting (SMC) processes, respectively and their microstructures and mechanical properties were investigated. The results indicate that casting method plays a remarkable influence on the microstructure and mechanical properties of as-cast NZ30K alloy. The grain size increases from 35-40 μm in the billets made by the DCC to about 100-120 μm in the billets by the SMC. The aggregation of Mg12Nd usually found at the triple joints of grain boundaries in the billets prepared by SMC while is not observable from the billets by DCC. The tensile strengths and elongations of the billets are 195.2 MPa and 15.5% by DCC, and 162.5 MPa and 3.2% by SMC, respectively. The tensile strength of the alloy by DCC is remarkably enhanced by T6 heat treatment, which reached 308.5 MPa. Fracture surfaces of NZ30K alloy have been characterized as intergranular fracture by SMC and quasi-cleavage fracture by DCC, respectively.
Effect of Multipoint Sequential Water Mist Cooling of Casting Die on Microstructure and Mechanical Properties of AlSi11 Alloy  [PDF]
R. W?adysiak
Archives of Foundry Engineering , 2012,
Abstract: The work is a continuation of research on the use of water mist cooling in order to increase efficiency of the die-casting process for aluminum alloys. The paper describes the multipoint sequential cooling system of the casting die and its computer control and monitoring.It also includes results of the tests and analysis of cooling methods during making of the casting. These methods differ from each other in the sequence of casting die cooling and cause effective changes in microstructure and mechanical properties of castings made of AlSi11 alloy. The study demonstrated that the use of multipoint sequential cooling with water mist affects the microstructure refinement and reduces the segregation in the cast as well as more than by 20% increases the mechanical properties of castings in the rough state. The study also demonstrates that the sequential cooling of casting die accelerates the cooling of the casting and shortens die-casting cycle.
Anodization of cast aluminium alloys produced by different casting methods  [PDF]
K. Labisz,L.A. Dobrzański,J. Konieczny
Archives of Foundry Engineering , 2008,
Abstract: In this paper the usability of two casting methods, of sand and high pressure cast for the anodization of AlSi12 and AlSi9Cu3 aluminium cast alloys was investigated. With defined anodization parameters like electrolyte composition and temperature, current type and value a anodic alumina surface layer was produced. The quality, size and properties of the anodic layer was investigated after the anodization of the chosen aluminium cast alloys. The Alumina layer was observed used light microscope, also the mechanical properties were measured as well the abrasive wear test was made with using ABR-8251 equipment. The researches included analyze of the influence of chemical composition, geometry and roughness of anodic layer obtained on aluminum casts. Conducted investigations shows the areas of later researches, especially in the direction of the possible, next optimization anodization process of aluminum casting alloys, for example in the range of raising resistance on corrosion to achieve a suitable anodic surface layer on elements for increasing applications in the aggressive environment for example as materials on working building constructions, elements in electronics and construction parts in air and automotive industry.
Effect of cooling rate on the microstructure and porosity of alumina produced by freeze casting  [PDF]
Rodríguez-Parra Jesús M.,Moreno Rodrigo,Nieto Isabel María
Journal of the Serbian Chemical Society , 2012, DOI: 10.2298/jsc121018132r
Abstract: Freeze casting is a well-known shaping technique to produce materials with directional porosity. One of the major problems is the difficulty to control the cooling rate thus leading to gradients in pore size and homogeneity. This work deals with the manufacture of alumina ceramics with directional porosity by freeze casting of aqueous suspensions. An experimental set-up was prepared in order to apply different cooling rates. Freeze casting tests were done with an aqueous alumina suspension after optimization of its rheological behavior. The porosity and microstructural features of sintered bodies produced under different experimental conditions were studied and analyzed. It is concluded that the cooling rate influences the microstructure while final temperature has a much lower influence. Also, the microstructural analysis shows that there is a gradient in the directionality of pores, being lower at the bottom and the top and higher in the central region of the specimens.
Proses Penuaan (Aging) pada Paduan Aluminium AA 333 Hasil Proses Sand Casting  [cached]
Anne Zulfia,Ratna Juwita,Ari Uliana,I Nyoman Jujur
Jurnal Teknik Mesin , 2010,
Abstract: The use of aluminum alloys AA 333 as automotive component is progressively expand with the expanding desire to lose weight from the used component. However, the as-cast product from aluminum alloys AA 333 is still having low mechanical properties, so it needs the other process to increase the hardness value; one of the processes is through heat treatment process. The heat treatment process for this materials is T6 process (artificial aging), including: solution treatment at temperature 525 oC for 8 hour, quenching and various time of aging process. Aging was conducted at 180 oC for 25 minutes, 1 hours, 5 hours, 8 hours and 16 hours respectively. For aging 5 hours, the aging temperature was applied various from 110 oC, 150 oC, 180 oC, 200 oC to 250 oC, so the expected result from this research is to know the influence of the variation to morphological change of microstructure and hardness value of aluminum alloys AA 333. The results had indicated that the aging process at 180 oC caused the increased of the hardness value of each phases: α-Al matrix, primary silicon, eutectic Al-Al2Cu and Al15 (Fe, Mn)3Si2 and also caused the increased of the hardness value of aluminum alloys AA 333, from the condition of as-cast, as-quench, aging process for 25 minutes, 1 hours, 5 hours, 8 hours and 16 hours. And others results had indicated that the aging process for 5 hours also caused increasing of hardness value of each phases. The aging process (at 180 oC) for 8 hours and 5 hours) represented the most optimum time to obtained the best combination from phase distribution, that spread over in the rich matrix of aluminum and the size measured from each phase, therefore giving the highest hardness value. in Bahasa Indonesia: Penggunaan paduan aluminium AA 333 sebagai komponen otomotif semakin berkembang bersamaan dengan semakin berkembangnya keinginan untuk mengurangi berat dari komponen yang digunakan. Namun paduan aluminium AA 333 as-cast masih memiliki sifat mekanis yang rendah sehingga diperlukan proses lain untuk meningkatkan kekerasannya, salah satunya melalui proses perlakuan panas. Proses perlakuan panas yang dipilih dalam penelitian ini adalah proses perlakuan panas T6 (artificial aging), yang meliputi tahapan: solution treatment pada temperatur 525oC selama 8 jam, quenching dan proses aging. Variabel yang digunakan dalam penelitian ini adalah variasi waktu aging (temperatur 180oC), yaitu 25 menit, 1 jam, 5 jam, 8 jam dan 16 jam dan variasi temperatur aging (waktu aging 5 jam), yaitu 110oC, 150oC, 180oC, 200oC, 250oC. Dari penelitian ini diharapkan dapat diketah
Thermal analysis as a microstructure prediction tool for A356 aluminium parts solidified under various cooling conditions  [PDF]
A. Niklas,U. Abaunza,A.I. Fernández-Calvo
China Foundry , 2011,
Abstract: Thermal analysis technique has been used for a long time, in both ferrous and nonferrous industries for evaluating the metallurgical quality of the liquid metal before casting. However, obtaining a proper microstructure in a standard cup does not ensure that the microstructure is correct in real parts which may solidify at very different cooling rates. For this study, alloy A356 with different metal quality in terms of modification and grain refinement was tested. Different cooling rates were obtained by using cylindrical test samples with various diameters cast in sand and metallic moulds. The correlation between microstructure features such as grain size, modification rate and secondary dendrite arm spacing (SDAS) measured in the standard thermal analysis cup with those obtained in the cylindrical test parts has been investigated. Thus, knowing the thermal modulus and the mould type it is possible to establish the required grain size and modification rate in the standard cup in order to get a desired structure in a real part. Corrective actions can then be taken in order to improve the metallurgical quality before casting the part.
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