Filtration Efficiency of Inclusions in Lightweight FeMnAl Steels
The efficiency of ceramic foam filters in removing different inclusion populations in a Fe-30Mn-9Al-1Si-0.9C-0.5 Mo steel was investigated. A mold design was created utilizing fluid flow and solidification modeling software. The design utilized a common pouring cup attached to two different but balanced gating systems. One runner utilized a ceramic foam filter while the other runner was unfiltered. Three molds were poured in sequence from a teapot style ladle. Metallographic samples revealed extensive Al and Mn rich oxide bi-films in samples taken before the filter. Samples sectioned after the filter did not contain bi-films. AlN or complex AlN-MnS or AlN-MnO comprised more than 70% of all inclusions. Samples sectioned from the first two molds showed an inclusion removal efficiency of 38% and 39%, respectively. Larger inclusions greater than 3µm were more efficiently filtered. The third mold with the greatest number of larger inclusions showed the highest inclusion removal efficiency of 55%.