Steel sheet and method for manufacturing the same
By controlling the alloy composition and heat treatment process, ultra-high strength steel plates with fine microstructure are formed, solving the problems of insufficient formability and hole expansion in existing technologies, and realizing the manufacturing of high-strength and high-ductility automotive structural components.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- POHANG IRON & STEEL CO LTD
- Filing Date
- 2024-12-02
- Publication Date
- 2026-06-19
AI Technical Summary
Existing technologies struggle to manufacture ultra-high strength steel sheets with high yield strength and high yield-to-strength ratio without compromising ductility and weldability, especially when used in automotive structural components, where formability and hole-expanding capabilities are insufficient.
By controlling the alloy composition and microstructure of the steel plate, ensuring that the proportion of tempered martensite and bainite in the steel plate is 60-90% and the proportion of retained austenite is 3-15%, and by using specific heat treatment processes including heating, hot rolling, cold rolling, annealing, cooling and over-aging treatment, a microstructure with an average particle size of less than 3μm is formed.
It achieves tensile strength of over 1180MPa, yield strength of over 800MPa, hole expansion of over 30%, and elongation of over 14%, thus improving the formability and local forming capability of the steel plate.
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