Experimental Studies on Al2O3 Inclusion Removal from Steel Melts Using Ceramic Filters.

Filtrationtests were made on AI-deoxidized iron melts in a 50 kg vacuum induction melting and casting unit using commercial foam, multi-hole and loop filters.Samplesfrom the solidified metal were prepared for chemical analysis and quantitative metallography.AI20.inclusions were produced by the addition of pure Al to the oxidized metal.Filtration efficiencies based on the content of chemically analysed total oxygen or oxidc particle size distribution weTe evaluated.Filtration of pure iron melts using ceramic foam filters reaches efficiencies up to 900/0.A minimum of total oxygen content around 20 to 30 ppm is attained independent from the initial oxygen content of the melt.Thelowest levels are achieved when25 ppi foam filters are applied.Filtration tests using I OOcpsi multi-hole filters for pure iron reveal filtration efficiencies of 80'/• and tota] removal of inclusions larger than 20um in diameter.Filtration efficiencies of 72 to 840/0 for pure iron were obtained using ceramic loop filters of different string diameters.Fromthe evaluation of volume flow capacities and filter resistances it was evident that casting time is prolonged up to the threefold as comparedto casting tests without integrated filters.Filtration of steel melts using ceramic foam, multi-hole or loop filters is an effective tool.High separation efficiencies are achieved, but filtration capacities of the porous filter media are limited in view of large steel volumes.