Solidification studies on sand cast Al 6061–SiCp composites

Most of the automotive components are cast and their performance depends very much on the solidification phenomenon. Solidification is primarily a process of achieving solid crystals from the liquid melt by promoting zones possessing very high cooling rates to ensure super cooling of the melt. Till date enormous data is available as regards the solidification behaviour of popular light alloys such as Al 6061 and A 356 with regard to the casting process, mould materials used and other important processing parameters. Effect of chills on the solidification behaviour of the above materials has also been reported suggesting chills to be an important promoter of directional solidification. Directional solidification results in minimized solidification defects. However, there is a lack of information regarding the effect of chills on solidification behaviour of aluminium based metal matrix composites which are currently the most potential candidate materials in automotive industries as a replacement for conventional light alloys. In the light of the above, this work is aimed at experimentally studying the solidification behaviour of Al 6061–SiCp castings in sand mould using copper and mild steel chills. Further, commercially available finite element analysis (FEA) software has been used to predict the cooling curves with and without the use of chills for the developed composite. The experimental and predicted cooling rates of the developed composites are not in good agreement. Use of copper chills resulted in promoting higher cooling rates during the solidification of developed composites.

Research highlights
► Solidification behavior of Al 6061-SiCp composites in sand moulds with and without use of chills have been investigated.
► Cooling rates of Al6061-SiCp composites have been determined experimentally and numerically.
► The experimental and predicted cooling rates are not in good agreement.