JPS6447806A - Production of cast iron - Google Patents

Abstract

PURPOSE:To produce cast iron having excellent mechanical strength and ductility by blowing granular carbonic additive in molten iron at the time of adding carbon for adjusting component after executing pretreatment to the molten iron of a blast furnace. CONSTITUTION:In the pretreating process, each process of desiliconization, desulfurization and dephosphorization on casting floor is executed to the molten iron tapped from the blast furnace to remove the impurities. Next, in case the carbon content is the pretreated molten iron is short, an injection lance 51 is set into the molten iron and the granular carbonic additive 52 is blown by carrying in Ar gas from this lance 51. Then, the carbonic additive 52 is desirable to use earthly graphite and this grain size is to regulate to <=about 2mm. Next, the silicon addition is executed and the temp. of the molten iron is raised up to about 1,450 deg.C and also the silicon is contained into the component in the molten iron and further, after adding Mg, it is cast. By this method, the cast iron improving the mechanical strength and ductility is produced at low cost.