A METHOD FOR MANUFACTURING WIRE ROD FOR ULTRA HIGH STRENGTH AND EXTRA FINE STEEL CORD

摘要

PURPOSE: A process for preparing the subject wire rods by controlling the diffusion cracking condition of bloom slabs and adjusting a cooling condition after rolling of wire rods is provided, which has an effect on manufacturing wire rods having a tensile strength of 120kg/mm¬2 or more and strand strength of 340kg/mm¬2 or more. CONSTITUTION: This wire rods are prepared by the process consisting of: continuous casting of molten steel containing by weight, C:0.84 to 0.88%, Mn:0.4 to 0.6%, Si:0.3% or less, Al:0.005% or less, N:20ppm or less and the balance of Fe with other inevitable impurities at a speed of 0.60 to 0.70m/min, preparing a billet, heat treating at 1,280 to 1,310deg.C for 5 hr or more, rolling, water quenching at 880 to 910deg.C, winding and air cooling at a speed of 10 to 15deg.C/sec.