2011 Volume 52 Issue 5 Pages 834-841
The effects of Fe, Mn and Fe/Mn-combined additions on the refinement of the spheroidized semi-solid α-Al grains in the wrought aluminum 6000 based alloy was investigated. The semi-solid microstructure control of Al-1.2%Mg-1.3%Si based alloys with Fe (1.0 mass%), Mn (0.7 mass%) and Fe/Mn-combined (1.0/0.7 mass%) additions was studied by the Deformation Semi-Solid Forming (D-SSF) process. This process consists of high deformation before semi-solid heating in order to introduce high density of dislocations and fragmentation of intermetallic compounds. Various second phase particles strongly affect the resultant α-Al grain size. The deformation process of the Fe-added alloy with a low rolling ratio produces fine α-Al grains with an average size of 76 μm, which is apparently smaller than that of the Fe-free alloy with an average α-Al grain size over 100 μm. The Mn addition required a high deformation ratio to achieve an average α-Al grain of 85 μm. The combination of Fe and Mn additions produces the finest grain size of 64 μm. The morphology of the Fe-intermetallic compound in the semi-solid forming process can be controlled by the cooling rate and Mn addition. The D-SSF process is a promising process to modify the harmful Fe impurity into the useful intermetallic compounds.