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The Study on the Formation Mechanism of Gas Pore During Lost Foam Casting of Al alloys  

Shin, Seung-Ryoul (Dept. of Materials Science Engineering, KAIST)
Han, Sang-Won (Dept. of Materials Science Engineering, KAIST)
Lee, Kyong-Whoan (Korea institute of Industrial Technology)
Lee, Zin-Hyoung (Dept. of Materials Science Engineering, KAIST)
Publication Information
Journal of Korea Foundry Society / v.23, no.5, 2003 , pp. 268-275 More about this Journal
Abstract
The mechanism of the hydrogen gas pore formation was investigated in Lost Foam Casting of Al-alloy by reduced pressure test and real casting. The hydrogen gas pick-up was affected by the formed gas during the decomposition of polystyrene in addition to the liquid product. It depended on pouring temperature and a proper temperature of metal front gave the minimum hydrogen pick-up. At a low pouring temperature, the hydrogen went into the melt mainly from entrapped liquid product of polystyrene but pores were formed from the gas as well as the liquid product at a high pouring temperature. The mold flask evacuation down to 710torr decreased the gas porosity down by around 0.4% vol%. The entrapped decomposition product of polystyrene in the melt was observed through the visualization of filling behavior of Al alloy-melt with the high speed camera.
Keywords
Lost Foam Casting; Hydrogen pick-up; Aluminum alloy; Polystyrene; Reduced pressure test.;
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