| 摘要 |
PURPOSE: A hot rolled steel sheet, a cold rolled steel sheet with high carbon and a production method are provided to secure high strength and high rigidity simultaneously and to eliminate a post annealing process. CONSTITUTION: A hot rolled steel sheet, cold rolled steel sheet with high carbon contains a high carbon rolled steel and micro perlite. A gap between laminated carbide layers on micro perlite has a uniform size within±20nm. Rolled steel with high carbon is prepared being composed of 0.9-1.2 weight% of C; less than 0.5 weight% of Si; 0.1-1.5 weight% of Mn; less than 0.05 weight% of P; less than 0.03 weight% of S; the remaining weight% of Fe; and other inevitable impurities. A micro perlite has a lamellar structure with layer spacing ranged 50-150 nm between the laminated carbides among microstructure of the rolled steel. The thickness of carbide composing the lamellar is 10-30 nm. [Reference numerals] (AA) Hot rolled steel sheet
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