ULTRA HIGH STRENGTH STEEL PLATE FOR PIPELINE WITH HIGH RESISTANCE TO SURFACE CRACKING AND MANUFACTURING METOD OF THE SAME

摘要

PURPOSE: An ultra high strength steel palate for a pipeline with excellent resistance to surface cracking and a manufacturing method thereof are provided to improve resistance to surface cracking by lowering the hardness of a surface part. CONSTITUTION: An ultra high strength steel palate for a pipeline with excellent resistance to surface cracking comprises C0.03~0.10 weight%, Si less than 0.6 weight%, Mn 1.6~2.1 weight%, Cu less than 1.0 weight%, Ni less than 1.0 weight%, Nb 0.02~0.06 weight%, V less than 0.1 weight%, Mo 0.1~0.5 weight%, Cr less than 1.0 weight%, Ti 0.005~0.03 weight%, Al less than 0.005 weight%, B 0.005~0.0025 weight%, N 0.001~0.006 weight%, Ca less than 0.006 weight%, P less than 0.02 weight%, S less than 0.005 weight%, and Fe and inevitable impurities.