| 摘要 |
PURPOSE: A manufacturing method of wire rod is provided which reduces surface decarburizing layer generated in high silicon steel and obtains low tensile strength required during cold forming due to high phase fraction of fine graphite powder by forming ferrite decarburizing layer having low carbon solubility in billet rolling process. CONSTITUTION: The manufacturing method of high silicon added medium carbon wire rod free from low temperature annealing comprises a step of obtaining a bloom comprising 0.40 to 0.60 wt.% of carbon, 2.0 to 4.0 wt.% of silicon, 0.1 to 0.8 wt.% of manganese, 0.01 wt.% or less of phosphorus, 0.01 wt.% or less of sulfur, 0.004 to 0.013 wt.% of nitrogen, 0.005 wt.% or less of oxygen, 0.001 to 0.003 wt.% of boron, 0.005 to 0.03 wt.% of titanium, one or more elements selected from the group consisting of 0.3 to 2.0 wt.% of nickel, 0.01 to 0.5 wt.% of vanadium and 0.01 to 0.5 wt.% of niobium, and a balance of Fe and other impurities, wherein the titanium (Ti), nitrogen (N) and boron (B) satisfy the following relational expressions: 0.5<=Ti/N<=2.0, 2<=N/B<=8, and 1.0<=(Ti+5B)/N<=3.5; a step of obtaining a billet by billet rolling the reheated bloom after reheating the bloom in the temperature range of 1,260±30 deg.C for 100±20 minutes; and a step of increasing temperature of the billet to a heating temperature of 1,050±50 deg.C at a heating rate of 10 deg.C/min or more, maintaining the billet in the temperature range of 1,050±50 deg.C for 30 minutes or more, and wire rod rolling the heated billet, thereby obtaining a wire rod.
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