Strength Steel Wire Research Articles

Improving strength of cold-drawn wire by martensitic transformation in a 0.65 wt% C low-alloy steel

Ultrahigh strength can be obtained by cold drawing of high-carbon steel wire, but the strength heavily relies on the extent of cold-drawn deformation and it is difficult to produce ultrahigh strength steel wire with large diameter. In this study, a new method by combination of cold-drawing and martensitic transformation was reported to significantly improve the strength of cold-drawn steel wire. By using the new method, the strength of the steel wire can be increased to over 2.4 GPa, which is much higher than its corresponding original cold-drawn wire (less than 2.0 GPa), while sacrificing only a small ductility. By using electrochemical etching, transmission electron microscopy and X-ray diffraction, the prior austenite grain size and the microstructure of the martensitic steel wires was analysed. After the heat treatment, the large cold deformed steel wire with 8 pass drawing displays grains of 4.9 μm and dislocation-substructured martensite; while the small cold deformed wire with 6 pass drawing results in coarser grains and a mixture substructure of dislocation and twin in martensite. The results demonstrate that the extent of cold-drawn deformation has a great influence on grain refinement in the later heat treatment; grain refinement to less than 5 μm will lead to martensite substructure transition from twin to dislocation, and thus endows the martensitic steel wire moderate ductility. In addition, calculation indicates that precipitate hardening and dislocation strengthening contribute about 76.9% to the yield strength, and martensite lath boundary strengthening contributes about 18% to the yield strength.

Influence of Carbon Content on the Mechanical Properties of Ultra-high Strength of Coated Steel Wire

Ultra-high strength of steel wire for offshore mooring lines can be achieved by increasing carbon content, addition of alloying elements and increasing cold work. The influence of carbon content and zinc coating on the tensile strength and torsion deformation have been investigated for drawn and hot dip galvanized steel wires at various drawing strain. In this work, experiments were conducted to increase the tensile strength of hyper-eutectoid steel wires by increasing carbon content from 0.87%wt to 0.98%wt. The samples with various diameter was drawn to their final diameter, then hot dip galvanized at 460ᵒC in a zinc bath to improve the anti-corrosion property. Torsion deformation has been investigated by twisting the drawn steel wires to different number of revolutions. Fractured samples after torsion test were analysed by optical and Field Emision Scaning Electron Microscope. The results showed that by increasing carbon content up to 0.98%wt (sample D) at drawing strain of 1.97 greatly increased the tensile strength up to 2338 MPa. However, delamination occurred at the zinc coating layer at strength exceeding 2250 MPa and the maximum limit of tensile strength of 0.92% C (sample D) is 2026 MPa without delamination. The effect of zinc coating layer on torsion degradation also revealed that the zinc alloy layer had a significant effect on delamination in the hot dip coating which associated with the higher carbon and silicon content (sample B) in the steel wires.

Tensile strength of steel wire in aqueous alcohol and alcohol solutions of HCl with Sb2O3 additions

Tensile strength of steel wire in aqueous alcohol and alcohol solutions of HCl with Sb2O3 additions

The influence of thermomechanical treatment upon the strength of steel wire

The influence of thermomechanical treatment upon the strength of steel wire