• Advances in Computational Design
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• v.7 no.2
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• pp.129-137
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• 2022

Compo-casting method is one of the popular technique to produce metal based matrix composites. But, one of the main challenges in this process is un-uniform spreading of reinforced subdivisions (particles) inside the metallic matrix and the lack of desirable mechanical properties of the final produced composites due to the low bonding strength among the metal matrix and reinforcement particles. To remove these difficulties and to promote the mechanical properties of these kind of composites, the WARM ARB technique was utilized as supplementary technique to heighten the mechanical and microstructural evolution of the casted Al/Al₂O₃ composite strips. The microstructure evolution and mechanical properties of these composites have been considered versus different WARM ARB cycles by tensile test, average Vickers micro hardness test, wear test and scanning electron microscopy (SEM). The SEM results revealed that during the higher warm- ARB cycles, big alumina clusters are broken and make a uniform distribution of alumina particles. It was shown that cumulating the forming cycles improved the mechanical properties of composites. In general, combined compo-casting and ARB process would consent making Al/Al₂O₃ composites with high consistency, good microstructural and mechanical properties.

• Journal of Korea Foundry Society
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• v.38 no.1
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• pp.9-15
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• 2018

Electromagnetic continuous casting (EMCC) was used to fabricate Ti-6Al-4V alloys with properties suitable for medical applications. Ti-6Al-4V alloy ingots fabricated by EMCC were subjected to heat treatment, such as residual stress removing (RRS), furnace cooling after solution treatment (ST-FC) and water-cooling after solution treatment (ST-WC), in order to obtain characteristics suitable for the standard. After component analysis, the microstructure and mechanical properties (tensile strength and elongation) were evaluated by ICP, gas analysis, OM, SEM, a Rockwell hardness tester and universal testing machine. The Ti-6Al-4V alloy ingot fabricated by EMCC was fabricated without segregation, and the lamellar structure was observed in the RRS and ST-FC specimens. The ST-WC specimen showed only martensite structure. As a result of evaluating the mechanical properties based on the microstructure results, we found that the water-cooled heat treatment condition after the solution treatment was most suitable for the Ti-6Al-4V ELI standard.

• Journal of Korea Foundry Society
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• v.32 no.4
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• pp.181-189
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• 2012

The microstructures of self-designed 7000 series Aluminium alloys added with Sc are observed. Moreover, the mechanical properties of the Sc-added Aluminium alloys are evaluated as a function of tensile temperature to establish the conditions of a following extrusion process. New casting conditions in the aluminium alloys added with Sc could be established by changing the casting speed and stirring time in the existing casting conditions of Aluminium alloys. The Sc addition results in $Al_3(Sc,Zr)$ precipitates in the cast alloys, and leads to the formation of equal-axed grains and fine grains. After homogenization heat treatment at $450^{\circ}C$, the Sc-added Aluminium alloys showed the highest elongation values in the temperature ranging from $300{\sim}400^{\circ}C$.

• Journal of Korea Foundry Society
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• v.30 no.6
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• pp.205-209
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• 2010

This study evaluates the influence of strontium addition and holding time on mechanical properties for Al-10.5wt%Si-2wt%Cu secondary die-casting alloy and the measured electrical conductivity of modified alloys. A general improvement in the mechanical properties of the alloy was observed after adding the strontium. Ultimate tensile strength, elongation and electrical conductivity of modified alloys were improved by increasing strontium content and holding time. From these results, the optimal strontium content and holding time were identified on the mechanical properties of Al-10.5wt%Si-2wt%Cu secondary die-casting alloys.

• Journal of Korea Foundry Society
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• v.18 no.3
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• pp.262-270
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• 1998

Gravity tilt pour casting can effectively guarantee the reduction of various casting defects by controlling the rotation speed and the tilting angle of the mold during tilt pouring. The relationship between casting process parameters and the soundness of castings has been investigated in order to determine the optimum process variables in the gravity tilt pour casting process. In order to evaluate the effect of rotation speed on mold filling patterns, a video camera was employed to visualize the in-situ fluid flow behavior of the molten metal, and the relevant fluid velocity was also estimated. X-ray and mechanical tests were also performed to evaluate the effect of fluid velocity on casting quality. With the rotation speed lower than 0.5 r.p.m., which is nearly corresponding to the critical velocity of stability in the fluid flow, sound castings were obtained without having any casting defects. It can be concluded that the gravity tilt pour casting process is an effective process for manufacturing sound casting products with enhanced physical and mechanical properties.

• Journal of Technologic Dentistry
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• v.32 no.4
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• pp.307-315
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• 2010

Purpose: The purpose of this study was to investigate the change of microstructures and mechanical properties of pure titanium casting specimens as a function of mold temperatures. Methods: The pure titanium castings were fabricated using the centrifugal vacuum casting method with different mold temperatures of $200{\sim}500^{\circ}C$. The resulting castings were characterized by optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and vicker,s hardness tester. Results: In case of the mold temperatures over $400^{\circ}C$, the porosity, surface crack and large grain size were observed in resulting castings. Conclusion: In this work, The most suitable mold temperature in casting of pure titanium was $300^{\circ}C$.

• Journal of Technologic Dentistry
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• v.25 no.1
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• pp.81-87
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• 2003

Ti-20%Zr-X%Cr(X=0,5) based alloys not containing hamful Al and V were newly designed in order to reveal their possibility for dental casting alloys, and melted in argon-arc casting machine. The mechanical properties were evaluated by using universal testing machine. The tensile strength and %elongaton of the alloys markedly increased with Cr content. The Ti-20%Zr-5%Cr alloy showed a similar tendency with Ti-6%Al-4%V alloy in tensile strength, but surpassed in %elongation. From these results, it was concluded that new alloys for successful dental casting materials should be designed as Ti-Zr-Cr based alloys.

• Journal of Korea Foundry Society
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• v.18 no.4
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• pp.373-382
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• 1998

Particulate reinforced aluminum alloys produced by indirect squeeze casting are difficult to shape by cutting or milling. Therefore near net shape forming of complex shapes is of high economic and technical interest. The complex shape products of $SiC_p/6061$ Al composites are fabricated by the melt-stirring and indirect squeeze casting process. The mold temperatures are $200^{\circ}C$ and $300^{\circ}C$ and applied pressures are 70, 100, and 130 MPa. The volume fractions of the reinforcements are in the range of 5 vol% to 15 vol%. The reinforcement dispersion state are observed using on optical microscope. By employing observed results systematically a correlation is demonstrated among the microstructure, particles behavior, mechanical properties and processing parameters for an optimum melt-stirring(compocasting) and indirect squeeze casting process of MMCs. A procedure to establish the optimum squeeze casting of Al-MMCs is proposed.

• Journal of Korea Foundry Society
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• v.14 no.5
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• pp.429-437
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• 1994

Influence of interfacial structure between matrix and particle in A356/coated SiC composite fabricated by squeeze casting method was studied. Experimental variables are types of coated metallic film on SiC particles such as Cu, Ni-P, and applied pressure for squeeze casting. It was found that coating treatment on SiC particles improves the wetting of liquid A356 alloy on SiC particles. SiC particle distribution is very homogeneous in A356 matrix alloy which is fabricated by squeeze casting. Analysing the surface morphology of fractured A356/coated SiC, it was concluded that metallic thin film by coating treatment on SiC particle improves the interfacial bonding between particle and matrix, and so does on mechanical properties such as tensile strength. However, there was on significant difference in hardness between those composite made of as-received SiC particle and coated SiC particle.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.60-63
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• 2003

Semi-solid forming is the process of stirring alloy during solidification, making the mixture of liquid and solid, solidifying it, reheating it to the solid-liquid coexistent temperature, and then injecting this semi solid slurry into dies. In the semi-solid die casting process, it is very important to find out the correlation of injection condition, microstructure and mechanical properties. Especially, an improper injection condition is the main cause of liquid segregation and non-homogeneous mechanical properties due to the difference of solid fraction according to the position of the products. To ensure the database requisite to the semi-solid die casting product, it is essential to acquire the mechanical properties considering liquid segregation to the injection condition. In this study, the effect of injection condition on liquid segregation, formability, microstructure and mechanical properties in a thin product was investigated.