Evaluation of Simultaneous Effect of Melt Filtration and Cooling Rate on Tensile Properties of A356 Cast Alloy

The combined in􀀕uence of both melt 􀀙ltration and cooling rate on the microstructure and mechanical properties of A356 cast alloy was studied. A step casting model with 􀀙ve different thicknesses was used to obtain different cooling rates. The effect of melt 􀀙ltration was studied by using 10 and 20 pores per inch (PPI) ceramic foam 􀀙lters in the runner. Results showed that secondary dendrite arm spacing decreased from 80 􀀭m to 34 􀀭m with increasing cooling rate. Use of ceramic foam 􀀙lters in the runner led to the reduction of melt velocity and surface turbulence, which prevented the incorporation of oxide 􀀙lms and air in the melt and consequently had an overall bene􀀙cial effect on the quality of the castings. A matrix index, which is the representative of both SDAS and microporosity content, was de􀀙ned to consider the simultaneous effect of melt 􀀙ltration and cooling rates on UTS variations. Also, the fracture surface study of test bars cast using 10 and 20 PPI ceramic foam 􀀙lters showed features associated with ductile fracture