Patent ID: 7462250

Claim:
A high strength and high toughness carbon steel wire rod containing C in an amount of 0.95 wt % or less, characterized by further containing, Zr in an amount of 10 wt ppm or more and 500 wt ppm or less and by including in said wire rod inclusions having a size of 0.1 to 10 μm, having a mole fraction of Zr of 0.2 or more in the ZrO 2 inclusions, and having a numerical density of 500 to 3000/mm 2 , and said wire rod has a 90% or more pearlite structure and an average value of the proeutectoid cementite area ratio of 5% or less in a center region of less than 20% of the wire rod radius from the center of said wire rod.