ULTRA-THICK STRUCTURAL STEEL HAVING EXCELLENT BRITTLE CRACK INITIATION RESISTANCE, AND MANUFACTURING METHOD THEREFOR

• Main Author: LEE HAKOL
• Format: Patent
• Language: Chinese; English
• Published: 10.08.2021
• 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; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PERFORMING OPERATIONS; PUNCHING METAL; ROLLING OF METAL; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS

One embodiment of the present invention provides an ultra-thick structural steel having excellent brittle crack initiation resistance, and a manufacturing method therefor, the ultra-thick structural steel comprising, by wt%, 0.03-0.08% of C, 1.6-2.2% of Mn, 0.6-1.3% of Ni, 0.005-0.03% of Nb, 0.005-0.02% of Ti, 0.1-0.4% of Cu, 100 ppm or less of P, 40 ppm or less of S, 1.5 ppm or less of H, and the balance of Fe and other inevitable impurities, wherein the sum of acicular ferrite and granular bainite in the microstructure is 80% or more by area fraction, the sum of the total length of cracks having a size of 30 [Mu]m or more per unit area of 1 mm in a +/-1 mm region on the basis of the thickness center of the steel is 130 [Mu]m or less, and the yield strength is 500 MPa or more. 本发明的一个实施方案提供了具有优异的脆裂萌生抗力的超厚结构钢及其制造方法，所述超厚结构钢按重量％计包含0.03％至0.08％的C、1.6％至2.2％的Mn、0.6％至1.3％的Ni、0.005％至0.03％的Nb、0.005％至0.02％的Ti、0.1％至0.4％的Cu、100ppm或更少的P、40ppm或更少的S、1.5ppm或更少的H、以及余量的Fe和其他不可避免的杂质，其中按面积分数计显微组织中的针状铁素体与粒状贝氏体之和为80％或更大，基于钢的厚度中心的±1