DIRECT-QUENCHED LOW CARBON MICRO-ALLOYED STEEL HAVING AN EXCELLENT STRENGTH AND IMPACT TOUGHNESS, AND A MANUFACTURING METHOD THEREOF

摘要

PURPOSE: A direct-quenched low carbon micro-alloyed steel having an excellent strength and impact toughness, and a manufacturing method thereof are provided to secure the strength of above 1000 Mpa and the impact toughness of above 100 J/cm^2.;CONSTITUTION: A manufacturing method of a direct-quenched low carbon micro-alloyed steel directly quenches a steel material after hot-forging at 1150 to 1250°C. The steel material comprises 0.08 to 0.20 wt% of C, 0.30 to 0.70 wt% of Si, 1.30 to 1.50 wt% of Mn, below 0.030 (excluding zero) wt% of P, 0.010 to 0.050 wt% of S, below 0.25 (excluding zero) wt% of Ni, 0.90 to 1.10 wt% of Cr, 0.10 to 0.20 wt% of Mo, 0.010 to 0.050 wt% of Nb, 0.0005 to 0.0030 wt% of B, 0.010 to 0.030 wt% of Al, 0.010 to 0.050 wt% of Ti, below 0.0080 (excluding zero) wt% of N, and remnants Fe and inevitable impurities. The steel from the steel material has a tensile strength of above 1000 Mpa and an impact toughness of 145 J/cm^2.;COPYRIGHT KIPO 2013