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A M A Mohamed - One of the best experts on this subject based on the ideXlab platform.
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influence of additives on the microstructure and tensile properties of near eutectic al 10 8 si cast alloy
Materials & Design, 2009Co-Authors: A M Samuel, F H Samuel, A M A Mohamed, H W DotyAbstract:Abstract The continuing quest for Aluminum Castings with enhanced mechanical properties for applications in the automotive industries has intensified the interest in Aluminum–silicon alloys. In Al–Si alloys, the properties are influenced by the shape and distribution of the eutectic silicon particles in the matrix, as also by the iron intermetallics and copper phases that occur upon solidification. The detailed microstructure and tensile properties of as-cast and heat-treated new experimental alloy belonging to cast Al–Si near-eutectic alloys have been investigated as a function of Fe, Mn, Cu, and Mg content. Microstructural examination was carried out using optical microscopy, image analysis, and electron probe microanalysis (EPMA), wavelength dispersive spectroscopic (WDS) analysis facilities. Tensile properties upon artificial aging in the temperature range of 155–240 °C for 5 h were also investigated. The results show that the volume fraction of Fe-intermetallics increases as the iron or manganese contents increase. Compact polygonal or star-like particles form when the sludge factor is greater than 2.1. The Al 2 Cu phase was observed to dissolve almost completely during solution heat treatment of all the alloys studied, especially those containing high levels of Mg and Fe, while Al 5 Cu 2 Mg 8 Si 6 , sludge, and α-Fe phases were found to persist after solution heat treatment. The β-Al 5 (Fe,Mn)Si phase dissolved partially in Sr-modified alloys, and its dissolution became more pronounced after solution heat treatment. At 0.5% Mn, the β-Fe phase forms when the Fe content is above 0.75%, causing the tensile properties to decrease drastically. The same results are obtained when the levels of both Fe and Mn are increased beyond 0.75%, because of sludge formation. On the other hand, the tensile properties of the Cu-containing alloys are affected slightly at high levels of Mg as a result of the formation of Al 5 Cu 2 Mg 8 Si 6 which decreases the amount of free Mg available to form the Al 2 CuMg phase. The results also show that, for the heat-treated alloys, peak aging is achieved at 180 °C, although the highest quality index corresponds to 155 °C aging temperature, for all the alloys investigated. Accordingly, 155 °C may be considered as the optimal aging treatment. It is also consistent with this observation that quality index is more sensitive to variations in tensile ductility than in tensile strength.
H W Doty - One of the best experts on this subject based on the ideXlab platform.
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metallurgical aspects of inclusion assessment in al 6 si casting alloy using the limca technique
International Journal of Metalcasting, 2018Co-Authors: A M Samuel, H W Doty, S Valtierra, F H SamuelAbstract:In the production of high-quality Aluminum Castings, melt cleanliness is important in regard to the performance and quality of the cast part and is determined, among other factors, by the inclusions present in the molten metal. Besides causing problems in process and quality control, other harmful consequences include reduced mechanical properties, poor machinability and increased porosity. Thus, control of melt cleanliness requires monitoring and minimizing the presence of impurities and inclusions. The liquid metal cleanliness analyzer (LiMCA) technique was used in the present study to investigate its capability for measuring inclusions such as Al2O3, Al4C3, MgO, CaO, TiB2 and TiAl3 typically found in Aluminum alloys, where these inclusions were added to Al–6%Si alloy melts using powder, master alloy, pure metal and metal matrix composite sources. Melts containing the different inclusion types were prepared, and the melt cleanliness was quantified using the LiMCA technique. Samplings for microstructural examination were also taken simultaneously. Evidence of the agglomeration of a vast amount of TiB2 inclusions as captured by the LiMCA probe tube shows that LiMCA is the only technique that is able to capture such agglomerates in-line, without any problem, as other techniques such as the PoDFA and Prefil cannot measure such TiB2 agglomerates without their filter systems getting clogged and interrupting the measurements. This is a significant finding and demonstrates a very important aspect of the LiMCA technique, particularly in view of the fact that Al–Ti–B master alloys are regularly employed for grain refining Aluminum casting alloys.
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influence of additives on the microstructure and tensile properties of near eutectic al 10 8 si cast alloy
Materials & Design, 2009Co-Authors: A M Samuel, F H Samuel, A M A Mohamed, H W DotyAbstract:Abstract The continuing quest for Aluminum Castings with enhanced mechanical properties for applications in the automotive industries has intensified the interest in Aluminum–silicon alloys. In Al–Si alloys, the properties are influenced by the shape and distribution of the eutectic silicon particles in the matrix, as also by the iron intermetallics and copper phases that occur upon solidification. The detailed microstructure and tensile properties of as-cast and heat-treated new experimental alloy belonging to cast Al–Si near-eutectic alloys have been investigated as a function of Fe, Mn, Cu, and Mg content. Microstructural examination was carried out using optical microscopy, image analysis, and electron probe microanalysis (EPMA), wavelength dispersive spectroscopic (WDS) analysis facilities. Tensile properties upon artificial aging in the temperature range of 155–240 °C for 5 h were also investigated. The results show that the volume fraction of Fe-intermetallics increases as the iron or manganese contents increase. Compact polygonal or star-like particles form when the sludge factor is greater than 2.1. The Al 2 Cu phase was observed to dissolve almost completely during solution heat treatment of all the alloys studied, especially those containing high levels of Mg and Fe, while Al 5 Cu 2 Mg 8 Si 6 , sludge, and α-Fe phases were found to persist after solution heat treatment. The β-Al 5 (Fe,Mn)Si phase dissolved partially in Sr-modified alloys, and its dissolution became more pronounced after solution heat treatment. At 0.5% Mn, the β-Fe phase forms when the Fe content is above 0.75%, causing the tensile properties to decrease drastically. The same results are obtained when the levels of both Fe and Mn are increased beyond 0.75%, because of sludge formation. On the other hand, the tensile properties of the Cu-containing alloys are affected slightly at high levels of Mg as a result of the formation of Al 5 Cu 2 Mg 8 Si 6 which decreases the amount of free Mg available to form the Al 2 CuMg phase. The results also show that, for the heat-treated alloys, peak aging is achieved at 180 °C, although the highest quality index corresponds to 155 °C aging temperature, for all the alloys investigated. Accordingly, 155 °C may be considered as the optimal aging treatment. It is also consistent with this observation that quality index is more sensitive to variations in tensile ductility than in tensile strength.
Hýbal Ondřej - One of the best experts on this subject based on the ideXlab platform.
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Development of ceramic shell for manufacturing of large Al investment Castings
Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018Co-Authors: Hýbal OndřejAbstract:This diploma thesis deals with the choice of the most suitable composition of a ceramic shell mold for Aluminum Castings made by investment casting technology. The most suitable composition of the ceramic shells is chosen based on the results of the tests and from economic point of view. This thesis also deals with evaluation of the current conditions of the production of ceramic shells in Alucast, s.r.o and recommendations for stabilizing the process of manufacturing ceramic shell molds
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Development of ceramic shell for manufacturing of large Al investment Castings
Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018Co-Authors: Hýbal OndřejAbstract:Tato diplomová práce pojednává o volbě nejvhodnějšího složení keramické skořepinové formy pro hliníkové odlitky lité metodou přesného lití. Nejvhodnější složení keramických skořepin je zvoleno na základě výsledků provedených zkoušek a také z ekonomického hlediska. Dále se tato práce zabývá zhodnocením současných podmínek výroby keramických skořepin ve slévárně Alucast, s.r.o. a doporučením pro stabilizaci procesu výroby keramických skořepinových forem.This diploma thesis deals with the choice of the most suitable composition of a ceramic shell mold for Aluminum Castings made by investment casting technology. The most suitable composition of the ceramic shells is chosen based on the results of the tests and from economic point of view. This thesis also deals with evaluation of the current conditions of the production of ceramic shells in Alucast, s.r.o and recommendations for stabilizing the process of manufacturing ceramic shell molds.
Alan A Luo - One of the best experts on this subject based on the ideXlab platform.
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predicting grain structure in high pressure die casting of Aluminum alloys a coupled cellular automaton and process model
Computational Materials Science, 2019Co-Authors: Emre Cinkilic, Jiashi Miao, Andrew D Klarner, Xinyan Yan, Alan A LuoAbstract:Abstract Grain structure is one of the most important factors that affect the mechanical properties of metallic alloys. Accurate prediction of as-cast grain structure is critical in the design and manufacturing of metal Castings using an integrated computational materials engineering (ICME) approach. In this paper, a three-dimensional (3-D) model based on cellular automaton (CA) and process simulation was developed for predicting grain size of components produced by high pressure die casting (HPDC) of Aluminum alloys. The concurrent nucleation and growth of grains were considered in the model. A test specimen casting, consisting of different wall thicknesses, was simulated using a finite element based casting process simulation software ProCAST®. The thermal history of the simulated casting was extracted and used in subsequent mesoscale CA modeling. Different thermal conditions were used to simulate grain nucleation and growth during HPDC. The grain morphology, grain density and grain size were obtained by CA modeling. Electron backscatter diffraction (EBSD) analysis was performed on Aluminum Castings of different wall thicknesses under various cooling rates to validate the simulation results. The 3-D grain structure model is in excellent agreement with the experimental results, and can be used in ICME design and development of Aluminum Castings.
John Campbell - One of the best experts on this subject based on the ideXlab platform.
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the effect of hot isostatic pressing hip on the fatigue life of a206 t71 Aluminum Castings
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: James T Staley, Murat Tiryakioğlu, John CampbellAbstract:The effect of hot isostatic pressing (HIP) on fatigue properties of A206-T71 Castings was investigated. Castings were (i) non-HIPed, or HIPed at (ii) typical HIP temperature, (iii) solution heat-treat temperature and (iv) eutectic melting temperature. HIP conditions were found to increase average and maximum fatigue life. However, the range in fatigue life also increased after HIP, which is attributed to the location of defects as well as HIP's ability to heal porosity and thin bifilms more effectively than thicker bifilms. The mechanism for healing bifilms by HIP appeared to be the fracture of bifilms and partial bonding across their surfaces. Fatigue life data were analyzed using three-parameter Weibull statistics, which showed that HIP significantly increases threshold fatigue life, but increasing HIP temperature has no effect on the threshold fatigue life.