Slag forming powder compsn. for casting steel - in which a proportion of the expanded mineral content is replaced by a graphite and mica contg. material

摘要

The slag forming powder comprises a slag, an expanded mineral which is free of carbon, and a flux. In addition an expanded material is present which contains a high level of a graphite material and a mica material of lamellar structure. The level of C is about half the total weight of the addn. and the level of mica about one fifth the total weight of the addn. Pref. the addn. is composed of naturally occurring graphite in which muscovite is embedded. Enables saving in cost as the powder compsn. has a higher insulating effect. The amt. of casting powder per ton steel can be reduced by 10-25% cf. conventional casting powders. Used pref. the addn. has the mineralogical compsn. graphite 40-50%, muscovite-illite 20%, fireclay 5-10%, chlorite 5%, quartz 10%, feldspar 3%, magnetite hematite trace, and the graphite has the compsn. 36.4% SiO2, 12.5% Al2O3, 0.5% TiO2, 1.7% K2O, 0.3% Na2O, 1.82% Fe, 0.03% Mn. 0.6% MgO, 0.3% CaO, 41.0% C, 1.0% CO2, 2.7% H2O. Pref. 2-10% (4-6%) of the graphite mineral material is added to the casting powder compsn., pref. together with the carbon-free expanded mineral. Used for casting steel ingots or in the continuous casting of steel.