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–0.5Mo 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 3 µm were more efficiently filtered. The third mold with the greatest number of larger inclusions showed the highest inclusion removal efficiency of 55%.