Gray cast iron for cylinder liner and method for manufacturing cylinder liner using the same

Abstract

A gray cast iron for a cylinder liner is provided that maintains fatigue strength and thermal shock property by adjusting component contents. The gray cast iron includes carbon (C) in an amount of about 3.2 to 3.7 weight % (wt %); silicon (Si) in an amount of about 2.0 to 2.8 wt %; manganese (Mn) in an amount of about 0.50 to 1.0 wt %; phosphorus (P) in an amount of about 0.20 wt % or less, and greater than about 0 wt %; sulfur (S) in an amount of about 0.10 wt % or less, and greater than about 0 wt %; chromium (Cr) in an amount of about 0.50 wt % or less, and greater than about 0 wt %; copper (Cu) in an amount of about 0.20 to 0.80 wt %; molybdenum (Mo) in an amount of about 0.10 to 0.40 wt %; and the balance of iron (Fe), based on the total weight of the gray cast iron.

What is claimed is: 
     
         1 . A gray cast iron for a cylinder liner, comprising:
 carbon (C) in an amount of about 3.2 to 3.7 weight % (wt %) based on the total weight of the gray cast iron;   silicon (Si) in an amount of about 2.0 to 2.8 wt % based on the total weight of the gray cast iron;   manganese (Mn) in an amount of about 0.50 to 1.0 wt % based on the total weight of the gray cast iron;   phosphorus (P) in an amount of about 0.20 wt % or less, and greater than about 0 wt % based on the total weight of the gray cast iron;   sulfur (S) in an amount of about 0.10 wt % or less, and greater than about 0 wt % based on the total weight of the gray cast iron;   chromium (Cr) in an amount of about 0.50 wt % or less, and greater than about 0 wt % based on the total weight of the gray cast iron;   copper (Cu) in an amount of about 0.20 to 0.80 wt % based on the total weight of the gray cast iron;   molybdenum (Mo) in an amount of about 0.10 to 0.40 wt % based on the total weight of the gray cast iron; and   the balance of iron (Fe),   wherein the gray cast iron satisfies the following Equation 1,
   0.8≦Cu+1.5Cr+1.2Mo≦1.5  [Equation 1]
 
   where Cu, Cr, and Mo respectively mean the contents in wt % of Cu, Cr and Mo components.   
     
     
         2 . The gray cast iron of  claim 1 , wherein the gray cast iron has a tensile strength of about 300 MPa or greater. 
     
     
         3 . The gray cast iron of  claim 1 , wherein the gray cast iron has a fatigue strength of about 140 MPa or greater. 
     
     
         4 . The gray cast iron of  claim 1 , consisting essentially of:
 carbon (C) in an amount of about 3.2 to 3.7 weight % (wt %) based on the total weight of the gray cast iron;   silicon (Si) in an amount of about 2.0 to 2.8 wt % based on the total weight of the gray cast iron;   manganese (Mn) in an amount of about 0.50 to 1.0 wt % based on the total weight of the gray cast iron;   phosphorus (P) in an amount of about 0.20 wt % or less, and greater than about 0 wt % based on the total weight of the gray cast iron;   sulfur (S) in an amount of about 0.10 wt % or less, and greater than about 0 wt % based on the total weight of the gray cast iron;   chromium (Cr) in an amount of about 0.50 wt % or less, and greater than about 0 wt % based on the total weight of the gray cast iron;   copper (Cu) in an amount of about 0.20 to 0.80 wt % based on the total weight of the gray cast iron;   molybdenum (Mo) in an amount of about 0.10 to 0.40 wt % based on the total weight of the gray cast iron; and   the balance of iron (Fe).   
     
     
         5 . A method for manufacturing a cylinder liner, comprising:
 manufacturing a molten steel comprising carbon (C) in an amount of about 3.2 to 3.7 weight % (wt %); silicon (Si) in an amount of about 2.0 to 2.8 wt %; manganese (Mn) in an amount of about 0.50 to 1.0 wt %; phosphorus (P) in an amount of about 0.20 wt % or less, and greater than about 0 wt %; sulfur (S) in an amount of about 0.10 wt % or less, and greater than about 0 wt %; chromium (Cr) in an amount of about 0.50 wt % or less, and greater than about 0 wt %; copper (Cu) in an amount of about 0.20 to 0.80 wt %; molybdenum (Mo) in an amount of about 0.10 to 0.40 wt %; and the balance of iron (Fe), based on the total weight of the gray cast iron; and   casting the molten steel by centrifugal casting,   wherein the components of the molten steel satisfy the following Equation 1,
   0.8≦Cu+1.5Cr+1.2Mo≦1.5  [Equation 1]
 
   where Cu, Cr, and Mo respectively mean the contents in wt % of Cu, Cr and Mo components.   
     
     
         6 . The method of  claim 5 , wherein after the centrifugal casting of the molten steel, the cylinder liner has a tensile strength of about 300 MPa or greater. 
     
     
         7 . The method of  claim 5 , wherein after the centrifugal casting of the molten steel, the cylinder liner has a fatigue strength of about 140 MPa or greater. 
     
     
         8 . A vehicle part that is manufactured from a gray casting iron of  claim 1 .