The present invention relates to a steel cord for rubber reinforcement. In the steel cord of the present invention, cobalt is contained by 0.001 ppm to 0.1 ppm within a 4 nm top-surface of the brass-plated steel wire. A method of manufacturing the steel cord includes: providing a brass-plated steel wire; mixing a cobalt compound in a wet lubricant filled in a wet drawing bath provided with a plurality of drawing dies between one pair of multi-stage drawing cones such that the concentration of the cobalt compound becomes 0.1 ppm to 100 ppm; and causing the cobalt to be contained by 0.001 ppm to 0.1 ppm within a 4 nm top-surface of the brass-plated steel wire after the brass-plated steel wire passes through a final die by causing the cobalt to be attached to a surface of the brass-plated steel wire and alloyed with a brass layer while the brass-plated steel wire is passing through the drawing cones and the drawing dies to be subjected to multi-stage drawing.

A process for drawing a steel wire, in which the wire has a carbon content by weight C of 0.4%C0.74%, includes an uninterrupted series of drawing steps. The drawing steps draw the wire from a diameter d to a diameter d, with d and d being expressed in mm, and with a true strain of the steel wire being given by =2ln(d/d), with >4.

A process for drawing a steel wire, in which the wire has a carbon content by weight C of 0.4%C0.74%, includes an uninterrupted series of drawing steps. The drawing steps draw the wire from a diameter d to a diameter d, with d and d being expressed in mm, and with a true strain of the steel wire being given by =2ln(d/d), with >4.

The ultra-fine wire fabricating apparatus comprises a feeder assembly, a stationary die, and a rotary die holder. The feeder assembly supplies a wire. The stationary die comprises a hollow inclined channel configured on an inner surface of the stationary die. The hollow inclined channel is configured to receive the wire from the feeder assembly. The rotary die holder configured to receive the wire from the stationary die and simultaneously torsionally deform the wire, wherein the rotary die holder rotates relative to the stationary die to produce the ultra-fine wire with improved mechanical properties. The method ensures continuous grain refinement of wires. The wires are severe plastic deformed using the combined effects of the stationary die and rotary die holder. The mechanical properties of the raw materials are improved due to a grain refinement and microstructure evolution caused by plastic deformation.

The ultra-fine wire fabricating apparatus comprises a feeder assembly, a stationary die, and a rotary die holder. The feeder assembly supplies a wire. The stationary die comprises a hollow inclined channel configured on an inner surface of the stationary die. The hollow inclined channel is configured to receive the wire from the feeder assembly. The rotary die holder configured to receive the wire from the stationary die and simultaneously torsionally deform the wire, wherein the rotary die holder rotates relative to the stationary die to produce the ultra-fine wire with improved mechanical properties. The method ensures continuous grain refinement of wires. The wires are severe plastic deformed using the combined effects of the stationary die and rotary die holder. The mechanical properties of the raw materials are improved due to a grain refinement and microstructure evolution caused by plastic deformation.

The present disclosure provides a copper-coated aluminum wire material including an aluminum wire material and a copper thin film coating the aluminum wire material that a space factor of the thin copper film is in the range of 0.2% to 4%.