Wire rods having superior strength and ductility for drawing and method for manufacturing the same

Abstract

There are provided a wire rod for drawing having superior strength and ductility and a method for manufacturing the same. The wire rod for drawing comprises, by weight: carbon (C): 0.87 to 1.0%, manganese (Mn): 0.1 to 0.60%, silicon (Si): 0.3 to 1.0%, sulfur (S): 0.010% or less (excluding 0%), phosphorus (P): 0.011% or less (excluding 0%), chromium (Cr): 0.1 to 0.5%, nitrogen (N): 0.007% or less (excluding 0%), and the balance of iron (Fe) and other inevitable impurities, wherein the sum of the Si and Cr contents satisfies the following equation: 0.6≦Si+Cr≦1.2 (the contents of Si and Cr is represented by ‘% by weight’), and the wire rod has a pearlite structure.

1 . A wire rod for drawing which has superior strength and ductility, comprising, by weight: carbon (C): 0.87 to 1.0%, manganese (Mn): 0.1 to 0.60%, silicon (Si): 0.3 to 1.0%, sulfur (S): 0.010% or less (excluding 0%), phosphorus (P): 0.011% or less (excluding 0%), chromium (Cr): 0.1 to 0.5%, nitrogen (N): 0.007% or less (excluding 0%). and the balance of iron (Fe) and other inevitable impurities, wherein the sum (% by weight) of the Si and Cr contents satisfies the following equation: 0.6≦Si+Cr≦1.2, and the wire rod has a pearlite structure. 
     
     
         2 . The wire rod for drawing of  claim 1 , further comprising 0.3% by weight or more of nickel (Ni). 
     
     
         3 . The wire rod for drawing of  claim 1 , wherein the wire rod has a tensile strength of 1300 MPa or more, and a 30% or more reduction of area. 
     
     
         4 . The wire rod for drawing of  claim 1 , wherein the pearlite structure of the wire rod has an interlamellar spacing of 130 nm or less. 
     
     
         5 . The wire rod for drawing of  claim 1 , wherein, after the wire rod is subject to a lead patenting process (LP, heat treatment prior to drawing), the pearlite structure of the wire rod has an interlamellar spacing of 50 nm or less. 
     
     
         6 . The wire rod for drawing of  claim 1 , wherein, after the wire rod is subject to a drawing process, the wire rod has 50 twists or more. 
     
     
         7 . A method for manufacturing a wire rod for drawing having superior strength and ductility, comprising: heating a wire rod at a temperature of 1100 to 1300° C., wherein the wire rod comprises, by weight: carbon (C): 0.87 to 1.0%, manganese (Mn): 0.1 to 0.60%, silicon (Si): 0.3 to 1.0%, sulfur (S): 0.010% or less (excluding 0%), phosphorus (P): 0.011% or less (excluding 0%), chromium (Cr): 0.1 to 0.5%, nitrogen (N): 0.007% or less (excluding 0%), and the balance of iron (Fe) and other inevitable impurities, wherein the sum (% by weight) of the Si and Cr contents satisfies the following equation: 0.6≦Si+Cr≦1.2, and the wire rod has a pearlite structure; hot-rolling the heated wire rod; and cooling the hot-rolled wire rod at a rate of 10 to 20° C./s. 
     
     
         8 . The wire rod for drawing of  claim 2 , wherein, after the wire rod is subject to a drawing process, the wire rod has 50 twists or more. 
     
     
         9 . The wire rod for drawing of  claim 3 , wherein, after the wire rod is subject to a drawing process, the wire rod has 50 twists or more. 
     
     
         10 . The wire rod for drawing of  claim 4 , wherein, after the wire rod is subject to a drawing process, the wire rod has 50 twists or more. 
     
     
         11 . The wire rod for drawing of  claim 5 , wherein, after the wire rod is subject to a drawing process, the wire rod has 50 twists or more.