Pass schedule of wire drawing process to prevent delamination for high strength steel cord wire

The high-speed drawing of high carbon content steel wires is usually conducted at room temperature employing a number of passes or reductions through several dies. In the multipass drawing process, the temperature rise at each pass affects the mechanical properties of the final product (such as its bending and torsion properties, and its tensile strength). This temperature rise during deformation encourages delamination in the wire, which has a deleterious influence on the torsional properties and durability of the wire. In this study, we investigated the delamination of wires using torsion tests and evaluated the wire temperature during drawing. Our data shows that one of the main reasons for delamination was an excessive rise in wire temperature. Based on our experimental results, in order to prevent delamination due to an excessive rise in wire temperature, a new isothermal pass schedule that could control the wire temperature was designed. The pass redesign for the conventional high carbon (0.75 wt%C) steel cord wire drawing process with delamination was carried out by using the isothermal pass schedule to control the wire temperature. In order to verify the effectiveness of the proposed method, wire drawing and torsion test were conducted. From the results of experiments, it was possible to produce high carbon steel cord wire without delamination.