| 摘要 |
PROBLEM TO BE SOLVED: To provide a high tensile strength hot rolled steel sheet which has excellent high speed deformation properties, i.e., is high in absorbed energy on high speed deformation in a deformation amount of 0.1 by true strain, and has excellent elongation properties, and to provide a method of producing the same. SOLUTION: The hot rolled steel sheet has a composition comprising 0.05 to 0.2% C, 0.8 to 2.5% Si, 0.5 to 2.5% Mn,≤0./015% P,≤0.01% S and≤0.05% Al, and the balance Fe with inevitable impurities. The steel sheet has a structure comprising, by area, 0.05 to 0.3% carbide of≤0.5μm in a diameter of the equivalent circle, 3 to 15% residual austenite, and≥60% ferrite, and in which the ratio of martensite is≤5%. The structure is obtained by controlling cooling/coiling conditions after rolling to specified ranges. COPYRIGHT: (C)2004,JPO
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