| 摘要 |
PURPOSE: A high-strength steel plate and a manufacturing method thereof are provided to manufacture a high-strength steel plate with excellent workability by controlling alloy components and process conditions without hot-rolling and cold-rolling processes. CONSTITUTION: A method for manufacturing a high-strength steel plate comprises: a slab reheating step(S110) for reheating a slab plate comprising 0.10-0.25 wt% of C, 0.03-2.0 wt% of Si, 1.0-2.0 wt% of Mn, 0.002-0.1 wt% of Al, 0.02 wt% or less of P, 0.005 wt% or less of S, 0.05 wt% or less of Cr, 0.01 wt% or less of N, and the rest of Fe and unavoidable impurities at a temperature of 1150-1250°C for 24 hours; a hot-rolling step(S120) for hot-rolling the reheated slab steel plate at an FDT(Finishing Delivery Temperature) of 700-850°C; a cooling step(S130) for cooling the hot-rolled plate at an average cooling speed of 100°C/sec or less, at a temperature of 350-450°C; and an air-cooling step(S140) for air-cooling the cooled plate at 250-50°C. [Reference numerals] (AA) Start; (BB) End; (S110) Slab reheating(SRT: 1200°C±50°C); (S120) Hot-rolling(FDT: 700-850°C); (S130) Cooling(100°C/sec or less, 300-450°C); (S140) Air-cooling(below 250°C)
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