The effects of pouring temperature on grain size of AC4CH aluminum alloy were studied by using sand mold with a chiller at one side of the casting. When poured from near liquidus temperature, the grain size fell under 100μm except in the area within a few mm from chill surface. The grain size is proportional to the −0.16th power of the cooling rate. On the other hand, when poured from higher temperatures, a dendrite structure appeared, and secondary dendrite arm spacing was proportional to the −0.41th power of the cooling rate. Refinement of grain size by low temperature pouring is due to the homogeneous nucleation of crystals at all over the test castings.

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  It is necessary for reduction of inferior castings due to porosity to clarify the shrinkage morphology of poured melt and the factors affecting its change. The change in the amount of porosity in the test castings was investigated from the viewpoint of hydrogen absorption with oxidation for JIS AC2B secondary alloy ingots. The amount of porosity changes with holding time and temperature of the molten metal as well as the humidity in the holding atmosphere, and the degree of the change differs according to the raw ingot because of the difference in the degree of the hydrogen absorption of the molten metal. Hydrogen absorption is closely related with the oxidation of the molten metal. In the case of the ingot containing both Mg and Ca, considerable hydrogen absorption occurred even during a short holding time, and the oxide formed on the melt surface sank. It is considered that the oxide sinks because Ca improves the wettability between the oxide and molten metal. This suggests that the oxidation of the melt is promoted, causing considerable hydrogen absorption.

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  The microstructure of flake graphite cast iron is the most important factor in determining the mechanical properties. The microstructure consists of two principal parts : the graphite and the matrix. Therefore, the present paper discusses the influence of the matrix and graphite morphology on mechanical properties. Graphite morphology was varied based on inoculation and holding of the melt and the addition of Ti. The influence of matrix on the tensile properties of cast iron were investigated using kinds of heat treatments. The experimental results were as follows : (1) The influence of graphite morphology on tensile strength of cast iron can be explained by the Rule of Mixture. (2) In the case of the difference of elongation between A-type graphite samples and D-type graphite samples is more than 0.4%, we can use the Rule of Mixtures. But when the difference is less than 0.2%, can not be used the Rule.

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  The corrosion behavior of step castings of Al-2.5%Li-2%Mg and Al-2.5%Li-1.2%Cu-0.7%Mg alloys with and without 0.15%Zr and 0.12%Ti were investigated by means of the water-salt spraying test. In the as cast state, weight loss by corrosion in the center part and near the surface part of the step castings of Al-Li system alloys is more or less the same as that of the conventional Al-7%Si-0.4%Mg alloy A356. This is due to the formation of corrosion products such as Na (CICN), Cu₃ (CO₃)₂ (OH)₂ and Al (OH)₃ over corrosive δ (AlLi) crystallized phases. In the Al-Li alloys aged at 453K for 36ks after solutionization, the corrosion resistance in the center parts of the castings becomes lower than in those of as cast ones. But in T6 treated Al-Li alloys, the corrosion resistance in the parts near the casting surface is high compared with that in the center parts, because of the difference in the amount of metastable state δ’ (Al₃Li), S’ (Al₂CuMg) and T₁(Al₂CuLi) precipitates.

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  This study is aimed at examining the influence of ultrasound-assisted exothermic reaction and improved wettability on the incorporation of Al₂O₃ particles into molten aluminum alloy in melt stirring. The Al₂O₃ particles with premixed nickel powder were added to molten Al-5mass%Mg alloy and stirred at a rotation speed of 16.7rps at 1023K in a nitrogen atmosphere. The ultrasound was then transmitted to the molten aluminum alloy with a ceramic plate. The application of ultrasonic vibration to melt stirring not only improves the apparent wettability, but also helps to dissolve the nickel powder thoroughly into molten aluminum alloy. The exothermic reaction of the nickel aluminide formation is promoted by ultrasonic vibration applied. This exothermic reaction leads to a local temperature rise of the molten aluminum alloy, which also improves the wettability. The ultrasound-assisted exothermic reaction of the nickel aluminide formation contributes to an increase in the engulfed Al₂O₃ particles and also the preparation of pore-free composite slurry.

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  Sand flowability and packing characteristic are extremely important in the evaporative pattern casting process. The sand in the flask must flow in to the surrounding areas of the expanded polystyrene foam pattern and compact density. The results of the experiment suggest that circular vertical plane vibration is useful for the filling of sand in the E. P. C process.

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  A experimental welding rod was made and welding tests were performed for the purpose of welding the spheroidal graphite cast iron at low preheat condition. AI, Bi, Ca, REM were added to the 3.9%C, 3.8%Si iron, and poured into the Cu mould to measure degree of chill by hardness, and determined the amount of each elements to be add avoiding serious chill for the experimental welding rod. It was performed a bead test on plate, repair welding test and a V groove welding for mechanical test by TIG welding using experimental welding rod. No crack was detected in the bead test on plate specimens even on the preheat condition of 369K. Hard chill was detected in the final layer under as weld condition for the repair welding test specimens, but as the distance from the final layer increased, fine graphits were found to increase considerably. Ferrite and fine graphite were detected at 10mm distance from the final layer in weld metal. The microstructure of heat treated specimen was ferrite and fine graphite in all deposited metal. A good tensile strength and fatigue limit was obtained in the mechanical tests of weld joint. The same welding rod and procedure were applied to spheroidal graphite iron casting with a thickness of 75mm, and the results were satisfactory.

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