High tensile strength steel wire

Abstract

A high tensile strength steel wire having as steel composition: a carbon content ranging from 0.20 weight percent to 1.00 weight percent, e.g. from 0.3 weight percent to 0.85 weight percent, e.g. from 0.4 weight percent to 0.7 weight percent, e.g. from 0.5 weight percent to 0.6 weight percent, a silicon content ranging from 0.05 weight percent to 2.0 weight percent, e.g. from 0.2 weight percent to 1.8 weight percent, e.g. from 1.2 weight percent to 1.6 weight percent, a manganese content ranging from 0.40 weight percent to 1.0 weight percent, e.g. from 0.5 weight percent to 0.9 weight percent, a chromium content ranging from 0.0 weight percent to 1.0 weight percent, e.g. from 0.5 weight percent to 0.8 weight percent, a sulfur and phosphor content being individually limited to 0.05 weight percent, e.g. limited to 0.025 weight percent, contents of nickel, vanadium, aluminum, copper or other micro-alloying elements all being individually limited to 0.5 weight percent, e.g. limited to 0.2 weight percent, e.g. limited to 0.08 weight percent, the remainder being iron, said steel wire having martensitic structure, wherein at least 10 volume percent of martensite are oriented.

Description

TECHNICAL FIELD[0001]The present invention relates to a high tensile strength steel wire, to a process for manufacturing a high tensile strength steel wire and to the uses or applications of such a high tensile strength steel wire as spring wire or an element for producing a rope.BACKGROUND ART[0002]Springs are usually made from alloys of steel. The most common spring steels are music wire, oil tempered wire, chrome silicon, chrome vanadium, and 302 and 17-7 stainless. Spring wires made of chrome silicon or chrome vanadium are higher quality, higher strength versions of oil tempered wire.[0003]Spring steel used in applications such as automotive valve springs is in general required to have a very high tensile and yield strength. Tensile strength is a material's ability to resist forces that attempt to pull apart or stretch it. Tensile strength is an important property for wires for spring applications. For instance, extension springs operating above their tensile strength will break...

AI Technical Summary

Benefits of technology

This patent text describes a wire drawing process that increases the strength of steel wire while maintaining its ductility. The process involves using a specific composition in combination with cold or warm drawing. The cold drawing method involves work hardening at temperatures below 400°C, which improves the material's mechanical properties and surface finish. The warm drawing method involves work hardening between 200°C and 700°C, which reduces the number of passes and simplifies the process. Overall, the invention provides a more effective and efficient way to produce high-quality steel wire.

Problems solved by technology

For instance, extension springs operating above their tensile strength will break.

It has been found, nevertheless, that increasing mechanical strength beyond certain limits causes such steels to have inadequate ductility, taking into account the pre-shaping and bending operations that have to be carried out with the spring wire.

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