A series of experiments were carried on aluminum alloy die casting using Al-8 mass % Si and Al-11 mass % Si alloy. The study is especially focused on clarifying the relation between the gate size and casting sproperty. Die casting when the gate thickness is changed from 1 to 4 mm, shows that cavity is filled completely with the melt at 4mm thickness and for a wide melt superheat range, whereas the filling condition becomes worse as the gate thickness decreases. Surface quality of the castings also drops with the decrease of the gate thickness. It is observed that the melt is likely to solidify near the gate as its thickness decreases. As the result, solid fraction in the metal increases during the cavity filling for a thin gate, leading to incomplete cavity filling and poor surface quality.

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  Adhesives such as thermosetting phenolic resin, urethane, epoxy resin and cyano-acrylate system are commonly used to bond strain gages and tensile specimens for strain measurement. The use of these adhesives in the tensile test resulted in embrittlement in austempered spheroidal graphite cast iron. Embrittlement due to use of adhesives is a characteristic of cast iron, since this behavior has not been reported in steels. The results obtained were as follows : (1) The tensile strength and elongation were reduced due to the coating by adhesives on ADI and quenched-tempered spheroidal graphite cast irons. (2) The reduction of elongation was increased with increasing graphite nodule diameter. (3) It suggested that the embrittlement of ADI and quenched-tempered ductile cast irons due to the coating by adhesives was caused by hydrogen embrittlement.

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  It is revealed that both the ultimate tensile strength and elongation are decreased remarkably by wetting austempered spheroidal graphite cast iron (ADI) with water at room temperature. The embrittlement behavior of ADI is investigated in detail and then the controlling methods of the embrittlement are proposed. Under the condition of wetting with water compared with the values under the dry condition (in the air), the ultimate tensile strength of ADI is decreased in the range from 65 to 80 % and also the elongation is decreased to about 10%. The white brittle fracture surface which is the starting point of failure is observed near the outer surface of the specimen. This is in contrast with the dimple pattern is usually formed in ADI tested in the air. The embrittlement behavior of ADI is depressed by the formation of ferrite layer on iron surface, because ferrite is not embrittled by water. The coating with paint for the purpose of avoiding direct contact with water is also efficient in depressing the embrittlement behavior. This is suggested that the drastic reduction of strength and ductility for ADI may be caused by hydrogen embrittlement.

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  The process of producing alumina particle dispersion Al-Si alloy slurry, and the wear properties of the product has been investigated. A thermit type reaction occurs when SiO₂ particles are added to the molten aluminum alloy. Consequently, hard alumina particles are distributed in the matrix alloy. The content of silicon in the matrix alloy increases because of reduction of the silica by molten aluminum. The potential ability of this method was clarified by measuring the rate of particles recovery and comparing with the conventional method of adding alumina particles. The composite had as good an anti-seizure property as the alumina aluminum alloy composite made by the conventional method.

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  CO₂ laser beam was applied to the drilling process of high manganese cast steel. The average drilled diameter was investigated by changing the functions of the laser power, irradiation time, gas pressure and type of assist gases used. The average drilled diameter increased with the laser power and irradiation time. An average drilled diameter of 0.33mm could be obtained under the conditions : laser power of 400 W, irradiation time of 0.5 s, gas pressure of 0.5 kPa and oxygen as the assist gas. The roughness of the drilled surface increased with the cutting speed in laser beam drilling. The smoothest drilled surface for drilling of 2 mm in diameter obtained was 25 μm (Ry) under the conditions : 400 W, 300 mm/min and 294 kPa of oxygen as the assist gas. The laser beam drilling process of this cast steel did not generate a heat affected zone around the boundary between the base metal and drilled surface. These results show that CO₂ laser beam drilling serves as a new drilling process for high manganese cast steel, which reduces physical labor and improves working conditions in foundry industries.

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  The metal injection molding process (MIM) is a key technology which makes it possible to form complicated 3-dimensional parts in near net shape. Cast iron has unique properties such as damping capacity. In this study, it is intented to study the properties of metal injection molded materials using cast iron powder. Water-atomized cast iron powder was deoxidized in vacuum. The deoxdized powder, spherical graphite powder, wax and resin were mixed and injected to the mold. The injected body was sintered by way of pre-sintering. The maximum tensile strength is 750 MPa which is comparable to that of ductile cast iron. The estimated damping capacity (logarismic decrement) is 450×10^-4, indicating exellent value as compared with gray iron. The reasons are considered as follows : Oxygen was reduced by carbon in the cast iron powder during deoxidization. Carbon diffuses to the matrix during pre-sintering. Graphite precipitates into the spherical pores during temperature drop after sintering. The high damping capacity and high tensile strength is considered to be obtained by the structure mixed with graphite particles and pores in matrix.

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