Method for treating molten cast iron

Abstract

A method for treating molten cast iron includes, performing an inoculation treatment to the molten cast iron, with the use of an inoculant containing: 15 to 80 wt % Si; either 80 to 100 wt % purity La or 80 to 100 wt % purity Ce as RE; Ca; Al; and the balance Fe with inevitable impurities, by adding the inoculant to the molten cast iron such that: the addition amount of La or Ce relative to the molten cast iron is 0.001 to 0.009 wt %; the addition amount of Ca relative to the molten cast iron is 0.001 to 0.02 wt %; and the addition amount of Al relative to the molten cast iron is 0.001 to 0.02 wt %.

1 . A method for treating molten cast iron including, performing an inoculation treatment to the molten cast iron, with the use of an inoculant containing: 15 to 80 wt % Si; either 80 to 100 wt % purity La or 80 to 100 wt % purity Ce as RE; Ca; Al; and the balance Fe with inevitable impurities, by adding the inoculant to the molten cast iron such that: the addition amount of La or Ce relative to the molten cast iron is 0.001 to 0.009 wt %; the addition amount of Ca relative to the molten cast iron is 0.001 to 0.02 wt %; and the addition amount of Al relative to the molten cast iron is 0.001 to 0.02 wt %. 
     
     
         2 . The method for treating molten cast iron according to  claim 1 , wherein, in the inoculant, the content of the Si is 30 to 80 wt %, the content of said 80 to 100 wt % purity La or said 80 to 100 wt % purity Ce is 0.1 to 0.6 wt %, the content of the Ca is 0.1 to 1.3 wt %, and the content of the Al is 0.1 to 2.0 wt %. 
     
     
         3 . The method for treating molten cast iron according to  claim 1 , wherein in the inoculant, the content of the Si is 30 to 80 wt/%, the content of said 80 to 100 wt % purity La or said 80 to 100 wt % purity Ce is 0.3 to 1.8 wt %, the content of the Ca is 0.1 to 6.0 wt %, and the content of the Al is 0.1 to 6.0 wt %. 
     
     
         4 . The method for treating molten cast iron according to  claim 1 , wherein the inoculant is in the form of granules each having a diameter of between 1 to 5 mm. 
     
     
         5 . The method for treating molten cast iron according to  claim 1 , wherein the inoculant is in the form of chunks each having a length of between 5 to 70 mm. 
     
     
         6 . The method for treating molten cast iron according to  claim 1 , wherein the inoculant is in the form of granules each having a diameter of between 0.1 to 1.0 mm, and wherein the inoculant are supplied to the molten cast iron with the granules being contained continuously in a core portion of a wire. 
     
     
         7 . The method for treating molten cast iron according to  claim 1 , further including performing a graphite spheroidizing treatment using a spheroidizing agent different from the inoculant, wherein the processing temperature of the graphite spheroidizing treatment is between 1400° C. to 1500° C. and the pouring temperature at which the molten cast iron is poured into a mold is between 1270° C. to 1370° C. 
     
     
         8 . A method for treating molten cast iron that performs a spheroidizing treatment and an inoculation by a sandwich method using the inoculant according to  claim 1 , and thereafter performs an inoculation in at least one of a ladle, a runner box, and a mold, using the inoculant. 
     
     
         9 . The method for treating molten cast iron according to  claim 8 , wherein the method performs combined multiple inoculations including a stream inoculation during pouring into the mold, an in-mold inoculation, and a pouring box inoculation. 
     
     
         10 . The method for treating molten cast iron according to  claim 1 , wherein the method includes performing, separately from the inoculation using the inoculant, a spheroidizing treatment using a spheroidizing agent containing magnesium. 
     
     
         11 . The method for treating molten cast iron according to  claim 2 , wherein the inoculant is in the form of granules each having a diameter of between 1 to 5 mm. 
     
     
         12 . The method for treating molten cast iron according to  claim 2 , wherein the inoculant is in the form of chunks each having a length of between 5 to 70 mm. 
     
     
         13 . The method for treating molten cast iron according to  claim 2 , wherein the inoculant is in the form of granules each having a diameter of between 0.1 to 1.0 mm, and wherein the inoculant are supplied to the molten cast iron with the granules being contained continuously in a core portion of a wire. 
     
     
         14 . The method for treating molten cast iron according to  claim 2 , further including performing a graphite spheroidizing treatment using a spheroidizing agent different from the inoculant, wherein the processing temperature of the graphite spheroidizing treatment is between 1400° C. to 1500° C. and the pouring temperature at which the molten cast iron is poured into a mold is between 1270° C. to 1370° C. 
     
     
         15 . The method for treating molten cast iron according to  claim 3 , further including performing a graphite spheroidizing treatment using a spheroidizing agent different from the inoculant, wherein the processing temperature of the graphite spheroidizing treatment is between 1400° C. to 1500° C. and the pouring temperature at which the molten cast iron is poured into a mold is between 1270° C. to 1370° C. 
     
     
         16 . A method for treating molten cast iron that performs a spheroidizing treatment and an inoculation by a sandwich method using the inoculant according to  claim 2 , and thereafter performs an inoculation in at least one of a ladle, a runner box, and a mold, using the inoculant. 
     
     
         17 . A method for treating molten cast iron that performs a spheroidizing treatment and an inoculation by a sandwich method using the inoculant according to  claim 3 , and thereafter performs an inoculation in at least one of a ladle, a runner box, and a mold, using the inoculant. 
     
     
         18 . The method for treating molten cast iron according to  claim 2 , wherein the method includes performing, separately from the inoculation using the inoculant, a spheroidizing treatment using a spheroidizing agent containing magnesium. 
     
     
         19 . The method for treating molten cast iron according to  claim 3 , wherein the method includes performing, separately from the inoculation using the inoculant, a spheroidizing treatment using a spheroidizing agent containing magnesium. 
     
     
         20 . The method for treating molten cast iron according to  claim 4 , wherein the method includes performing, separately from the inoculation using the inoculant, a spheroidizing treatment using a spheroidizing agent containing magnesium.