Steel and methods for manufacturing the same

By controlling cementite particle density and size through Cu and Ni addition and Ti nitride cores, the steel achieves superior cold workability by minimizing cracking and deformation resistance.

JP7865467B2Active Publication Date: 2026-05-26JFE STEEL CORP
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Patent Information

Authority / Receiving Office
JP · JP
Patent Type
Patents
Current Assignee / Owner
JFE STEEL CORP
Filing Date
2025-06-02
Publication Date
2026-05-26

AI Technical Summary

Technical Problem

Existing steels with reduced solid solution C and N for improved cold workability still suffer from cracking during cold working due to coarse cementite particles.

Method used

Control the number density and size of cementite particles by adding Cu and Ni, which do not form carbides, and incorporate Ti nitride cores to suppress carbide aggregation, along with specific microstructural and compositional controls.

Benefits of technology

The solution effectively suppresses cracking during cold working, ensuring high cold workability by reducing deformation resistance and enhancing the steel's microstructural integrity.

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Abstract

Provided is a steel that can suppress cracking during cold working. The steel according to the present invention has a prescribed component composition and a microstructure, and has a solid solution N content of 0.0015% or less and a hardness of 250 HV or less. Cementite particles having Ti nitride as the nuclei have a Cu and / or Ni enriched region around the particles, and the number density of said particles each having a circle-equivalent diameter of 10-100 nm is 20 particles / mm2 or greater. Moreover, for cementite particles as a whole, the number density of said particles each having a circle-equivalent diameter of 1 mm or greater is 10 particles / mm2 or less.
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