| 摘要 |
PURPOSE: A method for manufacturing a carbon steel wire rod for cold heading with improved spheroidizing structure by minimizing ferrite fraction while maximizing pearlite fraction is provided. CONSTITUTION: In a processing of a steel comprising C 0.40 to 0.50 wt.%, Si 0.10 to 0.35 wt.%, Mn 0.60 to 1.50 wt.%, 0.03 wt.% or less of P, 0.035 wt.% or less of S, Al 0.005 to 0.050 wt.% and incidental impurities using conventional carbon steel wire rod facility, the method is characterized in that a billet made of above steel is hot rolled after heat treatment at 1100 to 1150 deg.C, wherein the hot rolling is conducted at above 900 deg.C; and regulating the cooling start temperature in a temperature range of 780 to 900 deg.C, wherein the hot rolled wire rod is cooled at a cooling rate of 20 to 25 deg.C/sec over the temperature range of 650 to 900 deg.C, and cooled at a cooling rate of 10 to 15 deg.C/sec over the temperature range of 650 to 550 deg.C.
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