A parametric study of the evolution of microporosity in aluminum-silicon foundry alloys

Experimental data has been collected over a wide range of alloying and processing conditions in A356 alloy. A multiple regression analysis has been performed to correlate the casting parameters to the size and quantity of microporosity observed in the samples.; It has been found that the hydrogen content had the strongest influence on microporosity, and that both local solidification time and the local thermal conditions in the casting contributed to the final amount, size and shape of the pores. A hypothesis has been proposed which suggests that the pore growth is diffusion controlled. Factors that influenced the pore nucleation conditions, e.g. oxide inclusions and strontium content, have also been found to be important to the porosity. The relations describing pore size and total fraction porosity have shown quantitative differences.; Finally, previous assumptions used for modeling of porosity have been critically evaluated, and an outline for a new approach to mathematical modeling has been established.