Steel sheet and method for manufacturing same

By adjusting the steel composition and process conditions, high-strength steel plates with a yield strength of over 450 MPa and an elongation of over 20% were prepared, solving the problem of insufficient ductility in existing technologies. This makes the steel suitable for manufacturing tanks with complex shapes and reduces costs.

CN122095113APending Publication Date: 2026-05-26JFE STEEL CORP
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Patent Information

Application Number
CN202480067379.X
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Priority Date
2023-11-09
Filing Date
2024-10-30
Publication Date
2026-05-26

AI Technical Summary

Technical Problem

In existing technologies, high-strength steel plates have insufficient ductility, making them difficult to use in irregularly shaped tanks that require expansion, and the secondary cold rolling process increases costs.

Method used

By adjusting the steel composition, controlling the precipitation of Ti and Nb carbonitrides in the ferrite structure, and strictly controlling the coiling temperature of the hot rolling process and the heating rate of the annealing process, combined with cold rolling and leveling rolling processes, high-strength steel plates with excellent ductility and expandability are prepared.

Benefits of technology

It has achieved high-strength steel plates with a yield strength of over 450MPa and an elongation of over 20%, which are suitable for tank steel plates with complex shapes, promoting high strength and lightweight, and reducing costs.

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Abstract

The purpose of the present invention is to provide: a steel sheet which has excellent ductility and can expandability and has a yield strength (YP) of 450 MPa or more; and a method for producing the steel sheet. A steel sheet having a component composition containing, in mass%, 0.05% to 0.13% (inclusive) of C, 0.01% to 0.04% (inclusive) of Si, 0.1% to 0.6% (inclusive) of Mn, 0.02% or less of P, 0.02% or less of S, 0.01% to 0.10% (inclusive) of Al, 0.0005% to 0.0040% (inclusive) of N, 0.005% to 0.030% (inclusive) of Ti, 0.005% to 0.030% (inclusive) of Nb, 0.01% to 0.05% (inclusive) of Mo, and 0.0005% to 0.0050% (inclusive) of B, with the remainder comprising iron and unavoidable impurities, the steel sheet has a ferrite structure as a microstructure in an area ratio of 90% or more, and the total amount of Ti and Nb present in the form of carbonitride is 0.005% or more by mass% in the total amount of Ti and Nb.
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