High speed multi-stage drawing process of hot-dip galvanised steel wires

Abstract

In this paper, unique tests into the production of galvanised steel wires in industrial conditions were presented. It was demonstrated that three phenomena occur during the wire-drawing process at high speeds: namely, zinc sticking to the surface of drawing drums, zinc coating grinding caused by a larger friction surface area between the tool and the material, combined with the detachment of the zinc coating in the calibrating part of the die until the wire breaks and the drawing process is interrupted. After drawing at high speeds (over 15 m/s), the wires were characterised by a thin coat. The research carried out in the study showed a significant influence of the speed and the drawing angle on the mechanical and technological properties as well as the residual stresses in hot-dip galvanised steel wires. Depending on the speed of drawing, wires drawn in dies with an angle α = 7°, in relation to wires drawn in dies with an angle α = 3°, were characterised by 7.8–12% higher yield strength, and 3.7–7.1% higher tensile strength, 16.7% and 21.5% lower elongation, 24.3% lower reduction in area, 33% lower number of twist and bends, and 145.9% higher residual stresses.