Production manner null of the hard steel wire rod for cold drawing where wire drawing processability and fatigue property

摘要

PURPOSE: To produce a steel wire for cold wire drawing consisting of a tempered lower bainitic structure by hot-rolling a carbon steel or a high-medium carbon low alloy steel having a specified compsn., then quenching the hot-rolled wire rod to transform the wire rod and thereafter executing tempering. ;CONSTITUTION: A steel contg., by weight, 0.3 to 1.2% C, ≤1.2%, Si and ≤2% Mn and, as necessary ccompositely added with one or more kinds among ≤1% Cu, ≤1% Ni, ≤0.2% Ti, ≤0.3% Nb, ≤0.3% V, ≤0.5% Mo and ≤0.01% B is subjected to hot rolling to obtain the steel wire having ≤16mm wire diameter. This steel wire is quenched from an austenitic phase to the Ms point or above to 400°C, is held at the temp. for 5sec to 10min to complete the isothermal transformation, and is thereafter tempered at 300°C to the Ac₁. Thus, the hard steel wire rod having excellent cold wire drawability from the morphology and dispersing form of fine carbides, in which the texture of ferrite is formed by cold wire-drawing, and having high workability can be obtd.;COPYRIGHT: (C)1995,JPO