HIGH CARBON STEEL SHEET WITH SUPERIOR HEAT TREATMENT CHARACTERISTICS, AND MANUFACTURING METHOD THEREOF

摘要

The present invention provides a method for manufacturing a high carbon steel sheet, comprising the steps of i) producing a high carbon slab having a chemical composition comprising, by wt%, C 0.3-1.0%, Mn:0.1-1.2%, Si: more than 0 but less than 0.4%, Al: 0.01-0.1%, S: more than 0 but not more than 0.01%, the remainder being Fe and inevitable impurities ii) reheating the slab to the temperature higher than the Ar3 transformation point, iii) rough-milling the slab, and milling the slab again in an austenite region having a temperature higher than the Ar3 transformation point to produce a steel sheet, iv) cooling the steel sheet on a run-out table by the cooling speed of 50°C/second to 300°C/second, v) finishing the steel sheet cooling process at a temperature of 400-650°C, and maintaining the temperature, vi) winding the steel sheet at a temperature of 450-700°C, vii) omitting a pre-annealing process, and cold-rolling the wound steel sheet by a reduction ratio of 30% or higher; and viii) spheroidizing the cold-rolled steel sheet.