Steel plates and parts

A chemically and structurally optimized steel sheet addresses formability and impact resistance issues in high-strength steel sheets, enhancing ductility and impact resistance for complex automobile parts.

JP7776802B1Active Publication Date: 2025-11-27NIPPON STEEL CORPORATION
6 Cites 0 Cited by

Patent Information

Application Number
JP2025547487
Authority / Receiving Office
JP · JP
Patent Type
Patents
Current Assignee / Owner
Priority Date
2024-07-30
Filing Date
2025-07-23
Publication Date
2025-11-27
Estimated Expiration
2045-07-23

AI Technical Summary

Technical Problem

Existing high-strength steel sheets used in automobile parts face issues with formability, ductility, and impact resistance after pre-straining, particularly in complex shapes like automobile suspension parts, necessitating improved workability and impact resistance.

Method used

A steel sheet composition with controlled chemical elements and microstructure, including specific percentages of C, Si, Mn, P, S, Al, N, Ti, Cr, B, and others, along with a tailored metal structure of granular and acicular bainite, fresh martensite, tempered martensite, and retained austenite, optimized at different plate thickness positions to enhance strength, ductility, and impact resistance.

Benefits of technology

The solution provides a steel sheet with high strength, excellent ductility, and improved impact resistance after pre-straining, ensuring effective hole expandability and reduced cracking, suitable for complex automobile parts.

✦ Generated by Eureka AI based on patent content.
Patent Text Reader

Abstract

This steel plate has a predetermined chemical composition, and in its metal structure at a 1 / 4 position in the plate thickness, it contains, in area percentages, 30 to 50% granular bainite, 20 to 50% acicular bainite, 10 to 30% in total of one or more of fresh martensite, tempered martensite, and retained austenite, and less than 5% in total of one or more of ferrite and pearlite; and in the surface layer region, it contains, in area percentages, one or more of fresh martensite, tempered martensite, and retained austenite, and less than 10% in total of one or more of fresh martensite, tempered martensite, and retained austenite, and the average circle equivalent diameter of the MA phase consisting of the fresh martensite and the retained austenite, and the tempered martensite is 5.0 μm or less.
Need to check novelty before this filing date? Find Prior Art