Production method of flake graphite cast iron

Abstract

The invention provides a flake graphite cast iron being highly strong and excellent in workability such as cutting performance, which is suitable for use, for example, in internal combustion engine parts and the like, and a production method thereof without using a misch metal. Specifically, the flake graphite cast iron according to the invention includes an A-type graphite with a uniformly and disorderly distributed existence form without directionality; and has a chemical composition containing 2.8 to 4.0 mass % of C, 1.2 to 3.0 mass % of Si, 1.1 to 3.0 mass % of Mn, 0.01 to 0.6 mass % of P, 0.01 to 0.30 mass % of S and the remainder being Fe and inevitable impurities, wherein the ratio (Mn/S) of the Mn content to the S content is within a range of 3 to 300.

1 . A production method of a flake graphite cast iron comprising an A-type graphite with a uniformly and disorderly distributed existence form without directionality, said flake graphite cast iron having, in its state of a molten metal, a chemical composition containing 2.8 to 4.0 mass % of C, 1.2 to 3.0 mass % of Si, 1.1 to 3.0 mass % of Mn, 0.01 to 0.6 mass % of P, 0.01 to 0.30 mass % of S and the remainder being Fe and inevitable impurities, wherein said method comprises a step of adjusting the ratio of the Mn content to the S content (Mn/S) to be within a range of 3 to 300. 
     
     
         2 . The production method of a flake graphite cast iron according to  claim 1 , wherein the molten metal of the cast iron contains at least partly molten steel sheet scrap. 
     
     
         3 . The production method of a flake graphite cast iron according to  claim 2 , wherein at least one portion of the steel sheet scrap comprises a high-tensile steel sheet scrap containing not more than 3.0 mass % of Mn. 
     
     
         4 . The production method of a flake graphic cast iron according to  claim 1 , wherein a rare-earth element and a misch metal are not added during the adjustment.