Wire rod for high intensity steel wire, high intensity steel wire and these production methods

摘要

P To provide a steel wire which can be manufactured without being subjected to patenting treatment in a wire-drawing process and has superior mechanical properties such as strength and tensile strength; a wire rod to be used for manufacturing the steel wire; and a method for manufacturing them. PSOLUTION: The hot-rolled wire rod is made from a steel containing 0.30-0.50% C, 0.1-0.4% Si, 0.2-1.0% Mn, 0.01% or less Al and 0.01% or less Ti, 15-35 ppm N and 15-35 ppm O; includes pro-eutectoid ferrite and bainite of which the area rate FA (%) is in a range satisfying FA≤ - 70× (%C) +41, and pearlite which occupies 95% or more of the balance; and has a wire diameter of 3.6-7 mm. The steel wire is obtained by wire-drawing the wire rod at a true strain of 4 or more without subjecting the wire rod to the patenting treatment and bluing treatment and has a wire diameter D of 0.2-0.4 mm, has such a TS (MPa) as to satisfy 3,900-D× 2,600≤ TS and does not cause the occurrence of delamination in a twist test. PCOPYRIGHT: (C)2010 and JPO& INPIT