Effect of applied pressure on the microstructure and mechanical properties of squeeze-cast aluminum AA6061 alloy

Aluminum AA6061 alloy was squeeze cast under different pressure levels. The microstructure and mechanical properties of these castings were examined in the as-cast and heat-treated conditions to determine the effect of the squeeze pressure on the former. It was found that squeeze casting decreased both the volume fraction porosity and the micropore size as well as the size of the dendrites and of the interdendritic areas. The ultimate tensile strength of the as-cast and heat-treated castings increased with the application of pressure. However, the increase appeared to be independent of the magnitude of the applied pressure. The elongation was seen to reach a maximum at a pressure of 60–80 MPa, for all the samples, as-cast and heat-treated. The strength of the casting was also found to increase with increasing volume fraction of Mg2Si, and decrease with increasing volume fraction of (FeCrMn)3SiAl12 present in the casting.