HIGH-STRENGTH STEEL PLATE FOR A LINE PIPE HAVING EXCELLENT RESISTANCE TO HYDROGEN INDUCED CRACKING PROPERTIES AND A MANUFACTURING METHOD THEREOF, CAPABLE OF SATISFYING TM0284 STANDARDS WHICH IS STANDARDIZED BY NATIONAL ASSOCIATION OF CORROSION ENGINEERS THROUGH THE CONTROL OF ALLOY ELEMENTS

摘要

PURPOSE: A high-strength steel plate for a line pipe having excellent resistance to hydrogen induced cracking properties and a manufacturing method are provided to maintain S content to be less than 0.01 wt%, and Ca/S to be more than 2.3, thereby improving the resistance to hydrogen induced cracking properties and controlling the mannesman grade of a center segregation to be less than 2.;CONSTITUTION: A high-strength steel plate for a line pipe 0.04 to 0.08 wt% of C, 1.0 to 1.6 wt% of Mn, less than 0.3 wt% of Si, less than 0.01 wt% of P, less than 0.001 wt% of S, 0.01 to 0.05 wt% of Al, less than 0.005 wt% of Ca, less than 0.01 wt% of N, remnant Fe, and other inevitable impurities. The steel plate further includes less than 0.0021 wt% of Ca in a range in which 2.33≤[Ca]/[S]≤ 2.62(herein, [ ] is wt% of each element) is satisfied. The steel plate satisfies P≤0.001 wt% and C≤0.07 wt%. The steel plate includes at least one element of less than 0.08 wt% of Nb, less than 0.05 wt% of V, less than 0.02 wt% of Ti, and less than 0.3 wt% of Cr. The steel plate satisfies a CLR(Crack Length Ratio) of less than 15%, a CTR(Crack Thickness Ratio) of less than 5%, and a CSR(Crack Sensitivity Ratio) of less than 1.5%.;COPYRIGHT KIPO 2013;[Reference numerals] (AA) Pass; (BB) Failure