Investigation Of Heat Transfer Behavior During Mold Tilling And Solidification Process Of SiCp/A356Suction Castings

Composite is one of quite promising materials with high performance in application.With the development in recent decades, it has been widely applied to many fields ofaerospace, military and electronics industries and has shown more possibility for furtherapplication. Temperature changes during casting filling and solidification process havesignificant effect on the filling and solidification proceeding, and hence determine castingmicrostructure and performance in usage. In this investigation, by using facility of a suctioncasting made, the temperature variation during filling and solidification stages of the suctionA356-SiCp composite castings with different fraction reinforced particles was studied, andthe casting-mold interfacial heat transfer coefficient (HTC) during the solidification processwas calculated with the Inverse Method.In this paper, a facility for suction composite casting with temperature measurementwas designed and made. A356alloys and SiCp were selected as composite matrix materialand reinforced particle in the experiment. Four group SiCp/A356with different fractionreinforced particles were prepared by using of mechanical stirring, and then the suctioncomposite castings were produced, in which temperature measurement were carried outduring the casting filling and solidification process. According to the measured temperatures,overall trend of the temperature evolution was analyzed. The effect of the SiCp fractions onthe temperature change was discussed. Combining VC++program of the inverse method withsimulation code of the ANSYS APDL language, the casting-mold interfical HTCs werecalculated for the experiment conditions.The research reveals that SiCp/A356fluids flowed with turbulence during the suctioncasting filling process; with increase of the SiCp volume fractions, the composite viscositybecame larger, and the flow velocity decreased. In addition, the increase of the SiCp contentmade the composite temperatures decrease slowly during the mold filling. The reason for thisis considered that the increase of particle fractions reduces the contact areas of the compositefluid and mold, and it also increase the composite fluid viscosity decreasing wettabilty of the fluid and mold and their heat transfer.The comparison of the solidification temperature data has shown that with increasingSiCp volume fractions, the thermal conductivity of SiCp/A356increases resulting in thehigher cooling rate of the composites and the liquid-to-solid transformation temperatures godown due to less latent heat released; in the later period of solidification, more SiCp volumefractions, higher the composites temperature drop.The results of the calculated HTCs indicated that the coefficients reached peak values2-6s after the solidification start and then quickly reduced, and about40-50s later theyshowed relative stable values. The peak values of HTCs calculated for the A356,A356-5%SiCp, A356-10%SiCp, and A356-15%SiCp composite suction castingswere5363.37,4229.64,3829.61and2870.4W/(m~2·℃), respectively. This leads to that asSiCp volume fraction increases, HTC peak value at composite casting-mold interfacedecreases.