| Title |
Variation of Hydorgen Content and Microstructure of Semi-Solidified Al-4.5wt % Cu Alloy by Electromagnetic Stirring |
| Authors |
임정호(Jeong Ho Lim) ; 김정호(Jeong Ho Kim) ; 김기배(Ki Bae Kim) ; 윤의박(Eui Pak Yoon) |
| Abstract |
The quantitative analysis of hydrogen content together with the observation of the morphological changes in the microstructures of Al-4.5wt%Cu alloy induced by electromagnetic stirring was carried out. Hydrogen content was measured in two states. In the liquid state above the liquidus line hydrogen content was increased with increasing melt temperature and isothermal holding time. In semi-solid state using electromagnetic stirring hydrogen content was measured by high vacuum extraction method, according to the conditions of stirring such as cooling rate, input voltage and solid fraction. As the cooling rate was increased under the influence of stirring, the amount of hydrogen gas was increased. It is resulted from the fact that the diffusion of hydrogen due to the difference of hydrogen solubility between in liquid state and in semi-solid state is different with cooling rate. As input voltage was increased, hydrogen content was slightly decreased. This result was different from that of conventional cast, and it is explained in terms of the change of microstructures induced by electromagnetic stirring. However, hydrogen content with the solid fraction was not changed significantly. From above the results, it is also shown that both the changes of the microstructure and hydrogen content by electromagnetic stirring have influence on the type of porosity. |