| 摘要 |
PROBLEM TO BE SOLVED: To provide a high tension hot-rolled steel plate having≥780 MPa or further,≥980 MPa TS and satisfying TS×EL≥20,000 MPa% and TS×λ≥82,000, and its producing method. SOLUTION: This high tension hot-rolled steel plate has a composition composed of 0.04-0.25 mass% C, 0.4-2.0 mass% Si,≤3.0 mass% Mn,≤0.2 mass% Al,≤0.007 mass% S, 0.08-0.3 mass% Ti and the balance Fe with inevitable impurities and satisfying ([%C]/12 - [%Ti]/48)/([%Si]/28)≤0.4 in the above C, Si and Ti contents, and has a structure containing ferrite, bainite and retained austenite and≥40% the partial ratio of the above ferrite to the whole structure,≤5μm the average grain diameter of the above ferrite, 20-48% the partial ratio of the above bainite to the whole structure and 2-7% the above retained austenite to the whole structure. COPYRIGHT: (C)2004,JPO
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