ULTRA HIGH STRENGTH HOT-ROLLED STEEL SHEET HAVING EXCELLENT DUCTILITY AND METHOD FOR MANUFACTURING SAME

• Main Authors: SEO, Seok-Jong, KIM, Sung-Il
• Format: Patent
• Language: English
• Published: 20.08.2020
• 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

Provided is an ultra high strength hot-rolled steel sheet including, in percentage by weight: 0.15-0.25% of C, 0.6-2.0% of Si, 1.5-3.0% of Mn, 0.01-0.1% of Al, 0.01-0.5% of Cr, 0.005-0.2% of Mo, 0.001-0.05% of P, 0.001-0.05% of S, 0.001-0.01% of N, 0.003-0.1% of Nb, 0.003-0.1% of Ti, 0.003-0.1% of V, and the remainder being Fe and other unavoidable impurities, and satisfying following relational expressions (1) and (2). [Relational Expression 1] 4.5≤[Mn]+12[sol.C]+2.5[Mo]+2[Cr]+300[B]+[V]≤5.3. [Relational Expression 2] [sol.C]=[C]−(0.25[Ti]+0.13[Nb]+0.125[Mo]), 0.17≤[sol.C]≤0.22. (In relational expressions 1 and 2, each element symbol represents the content of each element in wt %.)