| 摘要 |
PURPOSE:To obtain a high tensile wire rod with little unevenness in tensile strength, a superior yield ratio and superior ductility by hardening a steel contg. specified components under specified conditions after hot rolling and by carrying out tempering and cold drawing at a specified reduction ratio in combination with each other. CONSTITUTION:A steel consisting of 0.20-0.40% C, 0.20-1.50% Si, 0.70-2.50% Mn, 0.10-1.50% Cr, 0.05-0.50% Mo, <=0.60% sol. Al and the balance Fe and inevitable impurities is hot rolled, immediately forced to cool to 500-700 deg.C, and spread on a conveyor in the form of a continuous ring at a supercooled austenite state. Cooling is carried out with a blast at >=7 deg.C/sec cooling rate to convert the structure of the whole wire rod into a martensite structure on the conveyor. The rod is then coiled at 200-300 deg.C, self-tempered by slow cooling, tempered by reheating to 400-600 deg.C, and cold drawn at <=10% reduction ratio. |
