• Journal of Korea Foundry Society
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• v.39 no.5
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• pp.87-93
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• 2019

The effects of mold materials on the microstructure and tensile properties were investigated to develop a mass production technique of aluminum alloy parts with excellent mechanical properties using a lost foam casting method. The microstructures of the plate-shaped cast alloy showed a tendency to be finer in proportion to the thickness of the plate, and a remarkably fine structure was obtained by applying a steel chill or a ball as a mold material compared to general sand. When a steel ball was used, it was observed that the larger the ball, the finer the cast structure and the better the tensile properties. The microstructure and tensile properties of the cast parts with complex shapes were greatly affected by the gating system, but the positive effects of the steel chill and the steel ball as a mold material were clear.

• Journal of Korea Foundry Society
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• v.20 no.5
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• pp.316-322
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• 2000

Effect of surface roughness and microstructure of the specimen on tensile properties of Ni-Al bronze casting has been investigated. surface roughnesses of the tensile test specimen of interest are in range of 0.1 to 2.0 ${\mu}m$ in Ra obtained by changing machining conditions. Fracture of the Ni-Al bronze casting initiated at the surface and propagated in a brittle manner during tensile tests. Tensile elongation value of the casting was strongly dependent on the surface roughness range studied, while tensile and yield strengths were almost independent on it. The elongation value was almost constant up to the surface roughness of 1.0 ${\mu}m$ in Ra, and then decreased in a linear manner with an increase in Ra value up to 2.0 ${\mu}m$. However, tensile strength and hardness were strongly dependent on the microstructure, especially ${\alpha}$ phase fraction, and were decreased with increasing ${\alpha}$ phase fraction in microstructure. It is, therefore, recommended that decrease of surface roughness up to 1.0 ${\mu}m$ in Ra, shrinkage porosity and ${\alpha}$ phase are required in order to obtain good tensile properties for Ni-Al bronze casting.

• Korean Journal of Materials Research
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• v.11 no.12
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• pp.1057-1062
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• 2001

We investigated the change of mechanical properties for TiNi shape memory alloy by heat treatment. 6061Al matrix composites with TiNi shape memory alloy as reinforcement were fabricated by vacuum casting. TiNi alloy has the maximum tensile strength at 673K treated and there is no change of tensile strength and hardness at 448K treated. The composites, prepared by vacuum casting, showed good interface bonding by vacuum casting. It was about 3$\mu\textrm{m}$ of thickness of the diffusion layer. Tensile strength of the composite was in higher than that of 6061Al alloy as increased value of about 70MPa at room temperature and about 110MPa at 363K. We thought that the increase of the tensile strength at 363K was due to reverse transformation of the TiNi shape memory alloy.

• Journal of Korea Foundry Society
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• v.21 no.2
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• pp.127-134
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• 2001

Misch metal (rare earth element, Ce, La, Nd, Pr) which has large influence on high-temperature stability and toughness was added to the Al-5%Ni-5%Mg alloy, and squeeze casting was used for Al-5%Ni-5%Mg-(Mm) alloys. The effect of applied pressure and misch metal additions on mechanical properties in Al-5%Ni-5%Mg alloy by direct squeeze casting has been investigated. The applied pressure were 0 MPa(gravity casting), 25, 50 and 75 MPa. Squeeze-cast Al-5%Ni-5%Mg-(Mm) alloys had better mechanical properties than those of non-pressurized cast alloys because of the increased cooling rate by the application of pressure during solidification. By the addition of misch metal in Al-5%Ni-5%Mg alloy, better combination of strength and elongation was obtained. The addition of 0.3%Mm in Al-5%Ni-5%Mg alloy improved the heat resistant property due to the formation of fine eutectic phases.

• Journal of Korea Foundry Society
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• v.36 no.6
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• pp.215-221
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• 2016

In a recent study, the microstructures and mechanical properties of AM80-xSn magnesium alloys with semi solid casting and hot extrusion process were investigated. With increasing Sn content, the amount of ${\beta}$(Mg2Sn) phase increased, while the ${\alpha}-Mg$ dendritic size decreased. The hardness was increased by the Mg2Sn as the Sn content increased. With increasing Sn content, permanent mold cast and semi solid cast AM80 Mg alloy showed less reduction of hardness and also of extruded AM80 Mg alloy after annealing. In the case of the mechanical properties, the extruded semi solid casting AM80 Mg alloy showed higher tensile strength and yield strength with increasing Sn content compared to the extruded permanent mold cast AM80 Mg alloy at room temperature.

• Journal of the Korean Society of Industry Convergence
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• v.9 no.2
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• pp.141-145
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• 2006

In case of sense case manufactured by method of outage capacity, sensitivity is declined by outside effect and method of the photo electricity has a problem in transmission. therefore, packing case of composite sense should be developed to improve such a problem about influence of outside environment and its property evaluation has been performed. Mechanical property and result of analysis & test evaluation of Mat'l on aluminum die-casting(ADC 12type) Mat'l developed are as following. Tensile test piece, No. 4 of KS B 0801, has been applied to mechanical property test of Mat'l and It has been tested by method of metal mat'l tensile test(KS B 0802 : 2003). It can be found that physical property to KS(Korea Standard) is excellent. and homogeneous mechanical property appears. Test of Mat'l analysis has been performed by using OE Spectrometer, according to ASTM E 1251 : 1994 regulation. Consequently, good and homogeneous component contents classified by element to standard, except for Fe, have been obtained with coordination of Fe content as below 1.3% from composition standard of Aluminum Die-casting.

• Journal of Sensor Science and Technology
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• v.32 no.3
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• pp.159-163
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• 2023

Salt cores have attracted considerable attention for their application to the casting process of electric vehicle parts as a solution to ecological issues. However, the salt core still has low mechanical strength for use in high-pressure die casting. In this study, we investigated the improvements in the bending strength of KCl-based salt cores resulting from the use of reinforcing materials. KCl and Na₂CO₃ powders were used as matrix materials, and glass fiber and carbon fiber were used as reinforcing materials. The effects of carbon fiber and glass fiber contents on the bending strength properties were investigated. Here, we obtained a new fiber-reinforced salt core composition with improved bending strength for high-pressure die casting by adding a relatively small amount of glass fiber (0.3 wt%). The reinforced salt core indicates the improved properties, including a bending strength of 49.3 Mpa, linear shrinkage of 1.5%, water solubility rate of 16.25 g/min·m² in distilled water, and hygroscopic rate of 0.058%.

• Journal of Korea Foundry Society
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• v.40 no.2
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• pp.34-42
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• 2020

The effects of the initial balancing pressure, filling pressure and maximum build-up pressure on the casting characteristics of the thick-wall thickness casting during the counter-pressure casting process were investigated. Water model experiment and a computer simulation were carried out to evaluate the characteristics during the filling and solidification stages in counter-pressure casting (CPC); as a reference, the low-pressure casting (LPC) process was used. The average dendrite cell size decreased with an increase in the solidification rate and maximum build-up pressure. A turbulent flow occurred during the filling stage of the LPC process, resulting in the formation of inner gas, while a lamellar flow pattern dominated during the CPC process and was more evident with an increase in the initial balancing pressure, improving the mechanical properties of the castings.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.415-418
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• 2005

In recent years, Magnesium (Mg) and its alloys have become a center of special interest in the automotive industry. Due to their high specific mechanical properties, they offer a significant weight saving potential in modem vehicle constructions. Most Mg alloys show very good machinability and processability, and even the most complicated die casting parts can be easily produced. The die casting process is a fast production method capable of a high degree of automation for which certain Mg alloys are ideally suited. Although Mg alloys are fulfilling the demands for low specific weight materials with excellent machining and casting abilities, they are still not used in die casting process to the same extent as the competing material aluminium. One of the reasons is that effects of various forming variables for die casting process is not closely examined from the viewpoint of die design. In this study, step die and flowability tests for AM60 were performed by die casting process according to various combination of casting pressure and plunger velocity. Microstructure and Victors hardness tests were examined and performed for each specimen to verify effects of forming conditions.

• Journal of Korea Foundry Society
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• v.10 no.1
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• pp.50-56
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• 1990

Continuous casting of the $Al-Al_3Ni$: eutectic composite was carried out by the upward continuous casting process. The morphology of the eutectic growth and the stability of solid-liquid interface were investigated under various growth conditions in an upward continuous casting. The effect of growth conditions on the mechanical properties of the $Al-Al_3$ Ni eutectic composit was also investigated, and the results were compared with those by the Bridgman method. As for the results, it was possible to get the planar solid-liquid interface at the condition of $G_L/R$＝$1.04{\times}10^3^{\circ}Csec/mm^2$. And the inter-rod spacing of $Al-Al_3Ni$ eutectic composite was decreased with the increase of pulling speed. The reduction of inter-rod spacing & value of $G_L/R$ caused the increase of ultimate tensile strength in $Al-Al_3Ni$: eutectic composite. The ultimate tensile strengths of $Al-Al_3Ni$ by the upward continuous casting were higher then those by the Bridgman method.