Steel wire and machine component

By controlling the chemical composition and microstructure of the steel wire, the problems of mold damage and low yield strength that occur in non-tempered bolts after strength improvement are solved, realizing the excellent formability of high-strength steel wire and the manufacture of mechanical parts with high yield strength.

CN120917170APending Publication Date: 2025-11-07NIPPON STEEL CORPORATION
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Patent Information

Application Number
CN202480023302.2
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Priority Date
2023-03-31
Filing Date
2024-03-29
Publication Date
2025-11-07

AI Technical Summary

Technical Problem

Non-heat-treated bolts are prone to damage, wear, and machining cracks in metal molds after their strength is increased. They also have low yield strength and high permanent elongation, which are difficult to improve by omitting the bluing process.

Method used

By controlling the chemical composition and metal structure of the steel wire, the composition and structure of the steel wire are ensured within a specific range, including the control of the area ratio of ferrite and martensite, optimization of tensile strength and yield strength, and avoidance of bluing treatment.

Benefits of technology

It achieves excellent formability of high-strength steel wire, enabling the attainment of high yield strength and suppression of permanent elongation without bluing treatment, thus improving the processing performance of metal parts.

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Abstract

The present invention pertains to a steel wire having a prescribed chemical composition, the steel wire having a content in mass% (element symbol%), a DI of 0.311 * (C%) 0.5 * (1 + 0.64 * (Si%)) * (1 + 4.10 * (Mn%)) of 1.40-4.50, a diameter D of the steel wire, a total area ratio of ferrite and martensite in a metallographic structure of a 1 / 4 D portion from the surface of the steel wire of 30.0% or less, F1 = (C%) + 0.10 * (Si%) + 0.18 * (Mn%) + 0.20 * (Cr%), and the balance of Fe and unavoidable impurities. The tensile strength is 860 * F1 + 450 MPa or more and 920 * F1 + 670 MPa or less, the value of (tensile strength-0.2% yield strength) / uniform elongation is 20 + 25 * (C%) or less, and the reduction in area is 66-48 * (C%) or more.
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Citation Information

Patent Citations

  • Manufacture of steel wire rod for non-heat treated bolt

    JP1990166229A

  • Steel wire, wire for non-heat-treated mechanical components, and non-heat-treated mechanical component

    JP2021183710A

  • Pencil or cosmetic shaft

    JP2023059431A

  • Rod material for non-tempered machine component, steel rod for non-tempered machine component, and non-tempered machine component

    WO2016121820A1

  • Steel wire for non-thermal-refined machine component, and non-thermal-refined machine component

    WO2017122830A1