Ductile iron

Abstract

A ductile iron having superior high-temperature strength and oxidation resistance at temperatures exceeding 800° C. compared with conventional high Si and Mo ductile iron. The ductile iron comprises, in terms of mass ratio, carbon: 2.0 to 4.0%, silicon: 3.5 to 5.0%, manganese: not more than 1.0%, chromium: 0.1 to 1.0%, molybdenum: 0.2 to 2.0%, vanadium: 0.1 to 1.0%, and magnesium: 0.02 to 0.1%, with the remainder being composed of iron and unavoidable impurities.

1 . A ductile iron comprising, in terms of mass ratio, carbon: 2.0 to 4.0%, silicon: 3.5 to 5.0%, manganese: not more than 1.0%, chromium: 0.1 to 1.0%, molybdenum: 0.2 to 2.0%, vanadium: 0.1 to 1.0%, and magnesium: 0.02 to 0.1%, with a remainder being composed of iron and unavoidable impurities. 
     
     
         2 . The ductile iron according to  claim 1 , further comprising a mass ratio of tungsten: 0.1 to 1.0%. 
     
     
         3 . The ductile iron according to  claim 1 , further comprising a mass ratio of niobium: 0.02 to 0.30%. 
     
     
         4 . The ductile iron according to  claim 1 , further comprising, in terms of mass ratio, tungsten: 0.1 to 1.0% and niobium: 0.02 to 0.30%. 
     
     
         5 . The ductile iron according to  claim 1 , wherein the spheroidization rate of graphite is 90% or higher. 
     
     
         6 . An exhaust system component, produced using the ductile iron according to  claim 1 . 
     
     
         7 . The exhaust system component according to  claim 6 , wherein the exhaust system component is a turbine housing, an exhaust manifold, or a turbine housing-integrated exhaust manifold. 
     
     
         8 . The ductile iron according to  claim 2 , wherein the spheroidization rate of graphite is 90% or higher. 
     
     
         9 . The ductile iron according to  claim 3 , wherein the spheroidization rate of graphite is 90% or higher. 
     
     
         10 . The ductile iron according to  claim 4 , wherein the spheroidization rate of graphite is 90% or higher. 
     
     
         11 . An exhaust system component, produced using the ductile iron according to  claim 2 . 
     
     
         12 . An exhaust system component, produced using the ductile iron according to  claim 3 . 
     
     
         13 . An exhaust system component, produced using the ductile iron according to  claim 4 . 
     
     
         14 . An exhaust system component, produced using the ductile iron according to  claim 5 .