发明公开
EP2617851A1 HIGH-STRENGTH HOT-ROLLED STEEL SHEET HAVING SUPERIOR PUNCHABILITY AND METHOD FOR PRODUCING SAME 有权
随着对生产优秀冲压和处理能力高强度热轧钢薄板

HIGH-STRENGTH HOT-ROLLED STEEL SHEET HAVING SUPERIOR PUNCHABILITY AND METHOD FOR PRODUCING SAME
摘要:
A high strength hot rolled steel sheet having excellent blanking workability is provided. The composition contains C: 0.050 to 0.15%, Si: 0.1 to 1.5%, Mn: 1.0 to 2.0%, P: 0.03% or less, S: 0.0030% or less, Al: 0.01 to 0.08%, Ti: 0.05 to 0.15%, N: 0.005% or less, and the balance being Fe and unavoidable impurities. More than 95% of the microstructure is formed of a bainite phase in terms of area fraction. Average grain diameters of the bainite phase in a region having a thickness equal to 1/4 of the sheet thickness from the surface in the sheet thickness direction is 5 µm or less in an L-direction cross section and 4 µm or less in a C-direction cross section. The number of crystal grains extended in the rolling direction and having an aspect ratio of 5 or more is 7 or less in a sheet thickness center portion. As a result, the strength is increased to a tensile strength TS of 780 MPa or more, the blanked edge forms a fine and uniform ductile fracture surface, and a hot rolled steel sheet having excellent properties at blanked edges and excellent blanking workability is obtained.
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