Steel wire with improved drawability, and manufacturing method therefor

Abstract

A steel wire with improved drawability, and a manufacturing method therefor are disclosed. A steel wire according to the present invention comprises, by wt %, 0.52-0.69% of C, 0.3-0.8% of Mn, 0.1-0.5% of Si, and the balance of Fe and inevitable impurities, wherein the carbon content of cementite in pearlite is 7 at. % or more, and the following formula (1) is satsified. [ TS ]+exp(ε)*10<1500  (1) In Expression (1), [TS] means the tensile strength (MPa) of a wire before drawing, and e means draw strain.

1 . A steel wire with improved drawability, which comprises, in weight percent, C: 0.52 to 0.69%, Mn: 0.3 to 0.8%, Si: 0.1 to 0.5%, a balance of Fe, and unavoidable impurities, has a carbon content of cementite in pearlite of 7 at % or more, and satisfies the following Expression (1),
     TS +exp(ε)*10<1500  (1)
   In Expression (1), TS denotes a tensile strength (MPa) of a wire rod before drawing, and ε denotes a drawing strain.   
     
     
         2 . The steel wire of  claim 1 , wherein the wire rod has a tensile strength of 700 to 1,000 MPa before the drawing. 
     
     
         3 . The steel wire of  claim 1 , wherein the torsion number of the steel wire is 27 or more. 
     
     
         4 . The steel wire of  claim 1 , wherein delamination does not occur at a drawing strain of 4.02 or less. 
     
     
         5 . A method for manufacturing a steel wire with improved drawability, comprising:
 hot-rolling a billet comprising, in weight percent, C: 0.52 to 0.69%, Mn: 0.3 to 0.8%, Si: 0.1 to 0.5%, a balance of Fe, and unavoidable impurities to obtain a wire rod;   cooling the hot-rolled wire rod at a cooling rate of 3 to 20° C./s; and   obtaining a steel wire by drawing the cooled wire rod to satisfy the following Expression (1),
   [ TS ]+exp(ε)*10<1500  (1)
 
   In Expression (1), [TS] denotes a tensile strength (MPa) of a wire rod before drawing, and ε denotes a drawing strain.   
     
     
         6 . The method of  claim 5 , wherein delamination does not occur at a wire strain rate of 4.02 or less during the drawing.