Hot-dip galvanized steel sheet and method for manufacturing the same

A high-strength hot-dip galvanized steel sheet with controlled composition and manufacturing process enhances peel strength and resistance to delayed delamination, addressing issues in automobile structural components.

JP7865463B2Active 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
2025-04-09
Publication Date
2026-05-26

AI Technical Summary

Technical Problem

Existing high-strength steel sheets used in automobile structural components face challenges with decreased peel strength of corona bonds, stress concentration, and delayed delamination of welds due to hydrogen intrusion, which are not adequately addressed by existing technologies.

Method used

A hot-dip galvanized steel sheet with a specified composition and microstructure, including a base steel plate with controlled carbon content and quenched martensite, combined with a hot-dip galvanized layer, is manufactured through a specific process involving hot rolling, cold rolling, annealing, and vibration cooling to enhance peel strength and resistance to delayed delamination.

Benefits of technology

The solution provides a hot-dip galvanized steel sheet with a tensile strength of 1180 MPa or higher, excellent formability, and improved resistance to delayed delamination of welds, addressing the issues of peel strength and stress concentration.

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Abstract

Provided is a hot-dip galvanized steel sheet having a TS of 1180 MPa or greater and excelling in the characteristics of bendability, peel strength of a corona bond, and delayed peeling resistance of a welded part. Also provided is a method for manufacturing the same. This hot-dip galvanized steel sheet is characterized by comprising a base steel sheet and a hot-dip galvanized layer formed on the surface of the base steel sheet, wherein the base steel sheet has a prescribed component composition and a prescribed steel structure, the C content in the surface layer of the base steel sheet is 0.150% or less, and a value obtained by dividing the C content in the surface layer of the base steel sheet by the C content in the entire base steel sheet is less than 0.85, and the hydrogen content [H] (ppm by mass) in the steel, the hydrogen having a binding energy of 10-100 kJ / mol with a hydrogen trapping site of the base steel sheet, satisfies formula (1) in which HvS is the average Vickers hardness of the surface layer of the base steel sheet.　(1): [H]≤(480-HvS) / 320
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