HIGH STRENGTH STEEL AND METHOD OF MANUFACTURING THE SAME

The present invention provides a high-strength steel comprising, by wt%, carbon (C): 0.13 to 0.17%, silicon (Si): 0.30 to 0.40%, manganese (Mn): 0.45 to 0.65%, phosphorus (P): greater than 0 and not more than 0.010%, sulfur (S): greater than 0 and not more than 0.003%, lanthanum (La): 0.01 to 0.04%, soluble aluminum (sol.Al): 0.006 to 0.025%, chromium (Cr): 1.0 to 1.1%, nickel (Ni): greater than 0 and not more than 0.10%, titanium (Ti): 0.005 to 0.015%, copper (Cu): 0.02 to 0.30%, niobium (Nb): greater than 0 and not more than 0.10%, molybdenum (Mo): 0.50 to 0.60%, vanadium (V): greater than 0 and not more than 0.10%, and the remainder of iron (Fe) and inevitable impurities. The final structure includes tempered martensite, tempered bainite, and ferrite structures. Thus, high-strength steel with high strength and low-temperature toughness is provided. 본 발명은, 중량%로, 탄소(C) : 0.13 ~ 0.17 %, 실리콘(Si) : 0.30 ~ 0.40 %, 망간(Mn) : 0.45 ~ 0.65 %, 인(P) : 0 초과 0.010 % 이하, 황(S) : 0 초과 0.003 % 이하, 란타늄(La) : 0.01 ~ 0.04 %, 고용 알루미늄(Sol.Al) : 0.006 ~ 0.025 %, 크롬(Cr) : 1.0 ~ 1.1 %, 니켈(Ni) : 0 초과 0.10 % 이하, 티타늄(Ti) : 0.005 ~ 0.015 %, 구리(Cu) : 0.02 ~ 0.30 %, 니오븀(Nb) : 0 초과 0.10 % 이하, 몰리브덴(Mo) : 0.50 ~ 0.60 %, 바나듐(V) : 0 초과 0.10 % 이하, 및 나머지 철(Fe)과 불가피한 불순물로 이루어지며, 최종조직은 템퍼드 마르텐사이트, 템퍼드 베이나이트 및 페라이트 조직을 포함하는, 고강도 강재를 제공한다.