• Journal of Korea Foundry Society
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• v.32 no.2
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• pp.86-90
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• 2012

Aluminium-silicon based casting alloys have received an attention for high electrical and thermal conductivity applications, however relatively low conductivity of Al-Si alloys often limits the application. Efforts have been made to develop new high conductivity aluminium casting alloys containing no or less silicon. In this study Al-Zn-Fe based alloys were selected as the new alloys, and the effect of Mg additions on their properties and casting characteristics were investigated. As the magnesium content was increased, the tensile strength of Al-2Zn-0.2Fe based alloy was remarkably increased, while the electrical conductivity was deteriorated. It was observed that the fluidity of the alloys was generally inversely proportional to the Mg content but the hot cracking resistance was rather proportional to it. Cooling curve analyses were carried out to measure the actual solidification range and dendrite coherency temperature.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.193-197
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• 2002

In this study, the casting/forging process was applied to the Shift-Fork, a manual transmission part of automobiles. In the casting experiments, the effects of additives, Sr, Ti＋B and Mg, on the mechanical properties and the microstructure of a cast preform were investigated. When 0.03% Sr were added into the molten aluminum alloy, the finest silicon-structure was observed in the cast preform and the highest tensile strength and elongation accomplished. And when 0.2% Ti＋B were added into the molten Al-Si alloy, the highest values of tensile strength were obtained. The maximum hardness was in case of 0.2% Mg. In the forging experiment, it was confirmed that the optimal configuration of the cast preform could be predicted by FE analysis. To minimize the cost as the press size, the compact shape of preform was proposed to reduce the volume of flash. The modification of shape in designing preform was performed to attain a satisfactory performance in the areas where the mechanical strength were more required. By using FVM(Finite Volume Method) software, it was verified that a proposed casting design was available. To identify the relationship between effective strain and mechanical properties of the final forged product, the compression test was performed. As the result, the tensile strength and elongation of a cast preform were much higher than before forging. The minimum forging temperature was found 40$0^{\circ}C$ to save heating time.

• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2767-2774
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• 2024

In this study, investment casting shell waste successfully utilized to produce cordierite/mullite/zircon composites. Green pellets, consisting of investment casting shell waste, alumina, and magnesia, were prepared and sintered at temperatures between 1250 and 1350 ℃. The influence of the sintering temperature on the crystalline phase composition, densification behavior, flexural strength, microstructure, and radiation shielding properties of the cordierite/mullite/zircon composites is investigated. Phase analysis showed that characteristic cordierite peaks appear at 1250 ℃, but the complete conversation of silica from investment casting shell waste into cordierite requires a sintering temperature of at least 1300 ℃. Notably, the cordierite/mullite/zircon composite sintered at 1350 ℃ exhibited a sixfold increase in flexural strength compared to the ceramic composite directly fabricated from investment casting shell waste at the same sintering temperature. Furthermore, the effect of Y₂O₃ addition on composites' radiation shielding properties is investigated. The results show that the Y₂O₃ addition improves densification behavior, enhancing the shielding capabilities of the composites against fast neutron and gamma radiation. Our findings suggest that the developed ceramic composites show significant potential for gamma-ray and neutron shielding applications.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2050-2054
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• 2007

This study numerically and experimentally investigated on thermal strain analysis of aluminum alloy casting mold using metal foundry. To predict the numerical result of thermal strain in Al alloy casting mold during the cooling process, it is performed the investigation of temperature distribution, stress and displacement based on the physical properties of Al alloy. In results of this study, Al alloy casting mold represented rapidly cooling graph during initial 20minutes after beginning cooling process, therefore value of stress and displacement is rapidly changed during initial 20minutes after beginning cooling process. In addition to, temperature distribution obtained by experiment confirmed corresponding pattern then compared numerical analysis with experiment. These results are distribute to make the effective and the high precision casting mold.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.139-142
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• 2003

In this study, casting/forging process was used to produce an aluminum lower control arm for automobiles. Firstly, casting experiments were carried out to get an enhanced preform for forging the lower control arm. In the casting experiment, the effect of an additive, Sr, on the mechanical properties such as tensile strength and elongation and the microstructure of a cast preform were investigated. And a finite element analysis was peformed to determine an optimal configuration of the cast preform. Lastly, a forging experiment was carried out to make the final product of aluminum lower control arm by using the above cast preform. In the casting experiments, when 0.025% Sr was added into molten A356, the maximum values of tensile strength and elongation of the cast preform were obtained. In the forging experiment, It was confirmed that the optimal configuration of a cast preform predicted by FE analysis was very useful. The cast/forged product using designed preform was made without any defects.

• Transactions of Materials Processing
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• v.11 no.4
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• pp.312-322
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• 2002

In this study, an innovative semi-solid die casting technology to replace heavier cast iron compressor parts with lightweight aluminum castings was proposed, and the application possibility for home-appliance component was investigated. The most important factors regarding the semi-solid die casting process are the reheating process of the raw materials to the semi-solid state, specifications of the forming machine, the optimal injection conditions and die design. Materials used in this study were A3S7 and hSn alloys fabricated by the electromagnetic stirring process. The optimal injection conditions for semi-solid die casting process were Presented with the reheating conditions of the semi-solid materials. To investigate the effect of plunger tip shape on the formability and mechanical properties in semi-solid die casting process for complicated shape part, two kinds of plunger tip shape with long and short plunger tip taper are proposed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.2
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• pp.348-355
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• 1992

Casting structures and properties are determined by the solidification speed in the metal mold. The heat transfer characteristics of the interface between the mold and the casting is one of the major factors that control the solidification speed. According to Sully's research, the thermal resistance exists due to the air-gap formation at the mold-casting interface during the freezing process and the interface heat transfer coefficient is used to describe the degree of it. In this study, one-dimensional Stefan problem with air-gap resistance in the cylindrical geometry is considered and heat transfer characteristics is numerically examined. The temperature distribution and solidification speed are obtained by using the modified variable time step method. And the effects of the major parameters such as mold geometry, thermal conductivity, heat transfer coefficient and initial temperature of casting on the thermal characteristics are investigated.

• Journal of Ocean Engineering and Technology
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• v.18 no.2
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• pp.70-76
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• 2004

In the steel marking industry, most companies have adapted the continuous casting process, due to its economical benefit. Casting rolls are utilized for frictional drive and the transport of solidifying slap. Dimensional tolerances, mechanical stability, and surface condition of the casting rolls can affect both the surface and the internal quality of the product being cast. To overcome these problems, the industry now is focused on accelerating the rate of technological improvements. This study has been undertaken for the development of casting rolls overlaid materials (SAW FCW wire), with the addition of Vanadium and Molybdenum to the martensitic stainless steel, in order to increase tensile strength and hardness at elevated temperatures.

• Korean Journal of Metals and Materials
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• v.49 no.6
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• pp.468-473
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• 2011

Determining the residual stress during casting processes is important for evaluating the mechanical properties and strength of materials and to optimize manufacturing conditions. In this study, we propose a field data interface procedure between FDM and FEM in a 3-dimensional space for analyzing the casting process and structural analysis. The casting process was analyzed using FDM and the data of the temperature distribution were converted into a format suitable for FEM analysis to calculate the thermal stress and safety factor by tightening force. The results of the coupled analysis between FDM and FEM showed that casting residual stress is an important factor in predicting life time and evaluating durability.

• Journal of Biomedical Engineering Research
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• v.24 no.5
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• pp.375-380
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• 2003

In this study. we have intended to control the properties of surface reaction zone generated between pure titanium and oxide investment moulds. Commercially pure titanium was centrifugally casted and silica$.$alumina based phosphate bonded investment was used as the mould material. The effect of cooling methods after casting on the surface reaction zone and mechanical properties of casts were investigated. The resulting casts showed the multilayered surface reaction zone regardless of cooling method. Especially. water cooling method produced the titanium casts with thinner surface reaction zone. weaker strength. and higher elongation properties compared to air cooling. It can thus be known that the resulting casts had satisfactory mechanical properties as dental materials. From these results, the cooling rate dependence of interfacial and mechanical properties can be attributed to the diffusion of oxygen from casting environment, which control the reaction of titanium and mould.