| 摘要 |
<p>PURPOSE: A steel material and a method for manufacturing the same are provided to evenly distribute carbide in a steel material and improve the strength and impact toughness of the steel material by properly controlling composition and manufacturing conditions. CONSTITUTION: A steel material having excellent strength and impact toughness comprises C of 0.04-0.20%, Mn of 0.3-2.5%, Si of 0.01-0.6%, Nb of 0.005-0.10%, Mo of 0.01-1.0%, Cr of 0.05-1.0%, Ti of 0.005-0.1%, Al of 0.005-0.5%, N of 15-150ppm, P of 0.02% or less, S of 0.01%, and Fe and inevitable impurities. The steel material also includes one or more selected from the group consisting of Cu of 0.010-1.0%, Ni of 0.01-2.0%, V of 0.005-0.3%, Co of 0.005-0.2%, and W of 0.005-0.2%. A carbide index(CI) expressed in relational equation 1, 0.146×Nb + 0.272×Ti + 0.261×V + 0.071×Mo + 0.081×W + 0.167×Cr + 0.037×Co, is 0.04-0.15.</p> |
