Papers by Author: Juan He

Abstract: Hydrogen is the only gas that is appreciably soluble in aluminum and its alloy. Its solubility is small but its effects on the mechanical properties and finishing characteristics of aluminum alloys are significant. In this paper, a patented degassing process, which is based on the vacuum metallurgy principle, is proposed. The diffusion equation was used for explaining hydrogen transfer in the liquid aluminum under the function of a porous sucking head. RPT experiment was carried out to evaluate effectiveness of the process. The experiment indicates that the hydrogen content can be dramatically reduced to 0.05ml/100gAl owing to the use of this new process.

Abstract: In this investigation, experiments were carried out to study the relationship of solidification parameters and the secondary dendrite arm spacing (SDAS) in A357 alloy casting with various thicknesses under the same solidification condition. The results show that the cooling rate decreases as the thickness of specimens increases, the local solidification time increased, and SDAS increased. The relationships between the SDAS and cooling rate and local solidification time under the condition of furan resin self-hardening sand casting were obtained: SDAS = 20.8 tf 0.3, SDAS = 69.34 v -0.3. The mechanical properties have some linear relations with SDAS of A357 alloy after aging heat treatment. The correlations can be expressed: UTS=410.4-0.8SDAS and El%=7.9-0.05SDAS.