METHOD OF MANUFACTURING HOT-ROLLED STEEL SHEET AND METHOD OF MANUFACTURING STEEL PIPE

• Main Author: CHUNG, JUN HO
• Format: Patent
• Language: English; Korean
• Published: 06.01.2016
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

The present invention discloses a method to manufacture a hot-rolled steel sheet and a method to manufacture a steel pipe, capable of performing a low-temperature normalizing process. According to the present invention, the method to manufacture the hot-rolled steel sheet comprises: a step of hot-rolling a slab sheet comprising 0.25-0.40 wt% of carbon (C), 0.15-0.30 wt% of silicon (Si), 1.2-2.5 wt% of manganese (Mn), 0.015 wt% or less of phosphorus (P), 0.005 wt% or less of sulfur (S), 0.01-0.05 wt% of aluminum (Al), 0.01-0.06 wt% of niobium (Nb), 0.02-0.05 wt% of titanium (Ti), 0.05-0.2 wt% of chrome (Cr), 0.01-0.1 wt% of molybdenum (Mo), 0.001-0.004 wt% of calcium (Ca), 0.008 wt% or less of nitrogen (N), and the remainder consisting of iron (Fe) and inevitable impurities in a finishing rolling temperature condition of 820-900°C cooling the hot-rolled sheet to 550-650°C and then winding the hot-rolled sheet. 저온 노말라이징 처리가 가능한 열연강판 제조 방법 및 강관 제조 방법에 대하여 개시한다. 본 발명에 따른 열연강판 제조 방법은 중량%로, 탄소(C) : 0.25~0.40%, 실리콘(Si) : 0.15~0.30%, 망간(Mn) : 1.2~2.5%, 인(P) : 0.015% 이하 및 황(S) : 0.005% 이하, 알루미늄(Al) : 0.01~0.05%, 니오븀(Nb) : 0.01~0.06%, 티타늄(Ti) : 0.02~0.05%, 크롬(Cr) : 0.05~0.2%, 몰리브덴(Mo) : 0.01~0.1%, 칼슘(Ca) : 0.001~0.004%, 질소(N) : 0.008% 이하 및 나머지 철(Fe)과 불가피한 불순물로 이루어지는 슬라브 판재를 820~900℃ 마무리압연온도 조건으로 열간압연하는 단계; 및 상기 열간압연된 판재를 550~650℃까지 냉각한 후, 권취하는 단계;를 포함하는 것을 특징으로 한다.