• Journal of Korea Foundry Society
• /
• v.30 no.4
• /
• pp.147-150
• /
• 2010

An eco-friendly production technique of Al-8.6Ti-0.025C refiner was developed by melting a Al-Ti master alloy in a graphite crucible, in which the potential nucleation site, TiC effectively formed by the spontaneous in-situ reaction between excessive Ti and carbon from graphite crucible. The A3003 alloy refined by the Al-8.6Ti-0.025C showed effectively refined macrostructure and enhanced mechanical properties comparable to the commercial Al-Ti-B refiner. The effective refinement was achieved in a shorter compare to the melt-treating time commercial Al-Ti-B refiner.

• Journal of Korea Foundry Society
• /
• v.25 no.4
• /
• pp.161-167
• /
• 2005

The experiment of hot dip interaction tests was carried out in order to study the formation behavior of interfacial reaction layer between as-received STD61 hot work tool steel and a commercial pure aluminum melt, Al-xwt.%Fe(x=0.2, 0.5, 0.8 and 1.1) alloys melt and Al-xwt.%Si(x=1.0, 4.0, 7.0 and 10.0) alloys melt, respectively. The results show that the reaction layer, over 300 ${\mu}m$ in thickness, is easily formed by the dissolution of silicon from as-received tool steel. When the iron content in the aluminum alloy is higher than 1.1 wt.%, the thickness of reaction layer decreases below 180 ${\mu}m$ by preventing iron dissolution from the tool steel. The silicon dissolved from tool steel acts as a strong promoter on the formation of reaction layer, but the alloyed silicon in molten aluminum alloys acts as an inhibitor on the formation of reaction layer.

• Journal of Korea Foundry Society
• /
• v.32 no.3
• /
• pp.127-132
• /
• 2012

Al-Zn-Mg alloys, being high strength aluminum alloys, have attracted attention as a material of automobile parts that require higher mechanical properties and lightness. Automobile parts with complex shapes are manufactured by low-priced casting method, but Al-Zn-Mg alloys are difficult to cast because of its poor hot cracking, feeding, and fluidity. Thus fluidity experiments on Al-Zn-Mg alloys were conducted for the castability evaluation. The effects of Mg and Zn, representative elements of Al-Zn-Mg alloys, on fluidity were observed. Spiral mold was used for fluidity experiments and the lengths of solidified specimens were measured after melting and gravity casting. Correlation between microstructures and fluidity length based on the alloy composition was considered. According to the experimental results, as the amount of Mg and Zn increased, fluidity decreased. Also, it was confirmed that fluidity change by the variation of Mg composition was greater than that of Zn.

• Resources Recycling
• /
• v.9 no.2
• /
• pp.46-52
• /
• 2000

Aluminum can to can recycling was divided into two stpes. The first step was composed of the processes such as collection of used beverage cans (UBC), shredding, magnetic separation, De-laquiring, melting and casting. The second one was remelting and casting, heat treating, hot and cold rolling, annealing, and can making. In this study, the effect of alloying elements on the microstructure and texture of the secondary ingots made by Al UBC was investigated. In aluminum can to can recycling, the second phase particles appeared in the solidification stage must be controlled by heat treatment. The optimum heat treatment condition was $615^{\circ}C$ for 5hrs. the texture in hot rolled sheet was depressed with increasing Mn content, on the other hand, Si and Fe elements promoted the texture development. The textures of can-body sheet should be controlled in the hot rolling and annealing stage because can was formed from cold rolled sheet without heat treatment.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.5
• /
• pp.791-799
• /
• 1997

The wear characteristics and wear mechanisms of plasma sprayed Al/sub 2/ O/sub 3/-40%TiO/sub 2/ and Cr/sub 2/O/sub 3/ deposited on casting aluminum alloy(AC4C) were investigated. Specimens were processed for various coating thicknesses. Ball on disk type wear tester was used for wear test. The scratch test on plasma sprayed coating surface showed that critical load to break the coating layer was greater than 40 N. The critical load increase with the increase of coating thickness of specimens. The friction coefficient of Cr/sub 2/O/sub 3/ coating layer was less than that of Al/sub 2/O/sub 3/-40%TiO/sub 2/ coating layer. The wear resistance of Cr/sub 2/O/sub 3/ coating layer was greater than that of Al/sub 2/O/sub 3/-40%TiO/sub 2/ coating layer. Microscopic observation of worn surfaces was made by SEM. SEM observation showed that the main mechanism of wear for Al/sub 2/O/sub 3/-40%TiO/sub 2/ coating layer was abrasive wear under 50 N. For the case of Al/sub 2/O/sub 3/-40%TiO/sub 2/ coating layer, as the surface cracks perpendicular to sliding direction propagated, the wear debris was generated in wear track. However, the main mechanism of wear for Cr/sub 2/O/sub 3/ coating layer was brittle fracture under 150 N.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.9
• /
• pp.1257-1263
• /
• 2010

The naval structure exposes to environmental vibration of shafted propeller propulsion and engine vibration. The shipboard equipments are developed compliance to MIL-STD-167-1A. For this purpose, vibration fatigue life of shipboard equipment for long lives should be estimate via an analytical approach and vibration test. In this paper, High cycle fatigue strength of cast aluminum alloy A356 using shipboard equipment was evaluated by 14 S-N method. The stress applied on the structure is evaluated by an analytical method(frequency response analysis with sinusoidal input and a fatigue evaluation) to simulate a MIL-STD-167-1A test. The frequency with the maximum equivalent stress is shown by Max. test frequency and the vibration fatigue life of shipboard equipment was estimated by Miner's rule.

• Journal of Korea Foundry Society
• /
• v.22 no.5
• /
• pp.257-264
• /
• 2002

Effects of Ca content on the refinement of primary Si of Aluminum B390 alloy have been examined. Ca was found to have an effect on the refinement of primary Si particle. Primary Si particle size has been refined as Ca content of the melts decreased and cooling rate increased. A control of Ca content by the addition of $CuCl_2$ to the melt was the most efficient in the refinement of primary Si particles. The minimum size of primary Si particles in this study was $15.0\;{\mu}m$ when a residual content of Ca element in the alloy was 5ppm, Primary Si particle size was refined as primary Si crystallization temperature increased, which was attributed to the decrease of Ca content in the melts.

• Journal of Korea Foundry Society
• /
• v.18 no.5
• /
• pp.481-487
• /
• 1998

Shell sand is widely used to make a complex shape castings due to its good collapsibility. When molten metal is poured into the mold, various gases are generated by the thermal decomposition of binder in the shell core. Casting defects such as blow hole and blister come from these gases. If it is possible to predict the evolution of gas quantitatively, it may provide effective solutions for minimizing the casting defects. To examine the gas evolution by shell core quantitatively, casting experiment and calculation were carried out. Gas pressure and gas volume evolved by shell core were measured in the experiment, and temperature distribution in the shell core was obtained by heat transfer analysis. From the result above, prediction on the gas volume evolved during pouring was tried. As forming pressure of the shell core increased and forming temperature decreased, the gas evolution increased. There was a close relationship between the calculated gas volume evolved and the measured one.

• Journal of Korea Foundry Society
• /
• v.25 no.4
• /
• pp.173-178
• /
• 2005

The vacuum molding process is one of the clean-foundry molding-processes that can recycle molding sands repeatedly, because molding can be accomplished by introducing vacuum only among dry molding sands in flask. The effects of molding conditions such as sand grain fineness, vacuum pressure and coating thickness on the fluidity of A356 Al alloy were studied and the results was obtained that the fluidity length was decreased as the sand grain fineness number and coating thikness were decreased and the vacuum pressure was increased. A large amount of heat removal from the molten metal resulting from the vacuum suction during the vacuum molding process was the principal cause of this decrease in fluidity.

• Journal of Korea Foundry Society
• /
• v.7 no.4
• /
• pp.352-357
• /
• 1987

Recently there were many studies on the development of cast iron for increasing strength, thermal resistance and mechanical properties, etc. The effects on mechanical properties and variation of solidification structure of hypo-eutectic cast iron was investigated when Ni(Al) was added with a fixed quantity of Al(Ni) content. The conclusions are as follows. 1) Tensile strength was the maximum(over 41 kg/ $mm^2$) when Al is added about 0.72%. 2) Torsional strength and angle were increased with increasing Al content and represents maximum value, when Al and Ni content are 1.5 and 2.0%. 3) With increasing Ni content, tensile strength decreased because of the effect of graphite coarsening. But torsional strengths were increased with the appropriate addition of (Ni%+Al%) content because of the effect of strengthened matrix.