Steel plates, components and their manufacturing methods
JP7632759B2Active Publication Date: 2025-02-19JFE STEEL CORP
Patent Information
- Application Number
- JP2024531141
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Priority Date
- 2023-01-30
- Filing Date
- 2024-01-25
- Publication Date
- 2025-02-19
- Estimated Expiration
- 2044-01-25
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Figure 0007632759000001 
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Abstract
Provided are a steel sheet and a member that have high strength as well as excellent bending workability and excellent resistance to delayed fractures, and production methods for these. The steel sheet contains, in mass%, 0.15% to 0.45% of C, 0.3% to 2.0% of Si, 1.7% to 4.0% of Mn, 0.10% or less of P, 0.01% or less of S, 0.50% or less of sol. Al, 0.010% or less of N, and 0.0008% to 0.0100% of B, with the remainder consisting of Fe and unavoidable impurities. The steel sheet has a steel structure in which the area ratio of martensite to the whole structure is at least 85% but less than 95%, and the area ratio of retained austenite to the whole structure is 5% to 15%. The number density A of precipitates having an equivalent circle diameter of 500 nm or more satisfies the formula: A (precipitates / mm2)≤8.5×105×[B].
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Citation Information
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