HIGH STRENGTH STRUCTURAL STEEL AND METHOD OF MANUFACTURING THE HIGH STRENGTH STRUCTURAL STEEL USING CONTROLLED ROLLING

摘要

PURPOSE: High-strength structural steel using control rolling and a manufacturing method thereof are provided to ensure yield strength of over 460MPa and Charpy impact of over 70J through control rolling in non-recrystallization temperature region. CONSTITUTION: A method of manufacturing high-strength structural steel comprises next steps. Slab steel is re-heated(S110). The re-heated steel is hot rolled(S120). The final hot rolling temperature is controlled so that the rolling reduction in a non-recrystallization temperature region(Tnr) becomes 20~45% of the thickness of steel before rolling. The hot rolled steel is cooled(S130). The slab steel comprises C of 0.14~0.16 weight% and V of 0.04~0.09 weight%. The slab steel consists of Si of 0.25~0.35 weight%, Mn of 1.25~1.35 weight%, P of 0.03 weight% or less, S of 0.015 weight% or less, Nb of 0.035~0.045 weight%, N of 0.015 weight%, Fe and other inevitable impurities.