| 摘要 |
<p>A high carbon steel sheet excellent in strength and toughness without using expensive alloy elements is provided, and a manufacturing method of the high carbon steel sheet is provided. A manufacturing method of a high carbon steel sheet excellent in strength and toughness comprises: a steel manufacturing step of manufacturing a steel for heat treatment comprising, by weight percent, 0.25 to 0.55% of C, 0.5 to 1.2% of Mn, more than 0 and not more than 0.4% of Si, more than 0 and not more than 2.0% of Cr, 0.01 to 0.1% of Al, more than 0 and not more than 0.012% of S, not less than 48/14x[N]% of Ti, 0.0005 to 0.0050% of B and not more than 0.006% of N with the balance being Fe and other inevitable impure elements, and satisfying a condition of 48/14x[N] to 0.03% of Ti in case of 0.0005<=B<=(11/14)x[N]%; a hot rolling step of heating the steel for heat treatment at a temperature of 1200 to 1250 deg.C to hot roll the steel for heat treatment; a coiling step of coiling the hot-rolled steel sheet in a temperature range of 640 to 700 deg.C; a cold rolling step of cold rolling the hot-rolled steel sheet to reduce thickness of the hot-rolled steel sheet; a heat treatment step of subjecting the cold-rolled steel sheet to an austenitizing heat treatment in a temperature range of Ac1 to Ac3 transformation temperature; and an austempering heat treatment step of subjecting the heat-treated steel sheet to an isothermal transformation treatment at 350 to 500 deg.C.</p> |
