STEEL PLATE WITH EXCELLENT HYDROGEN INDUCED CRACKING RESISTANCE, AND MANUFACTURING METHOD OF THE SAME

摘要

A steel plate is provided which has excellent hydrogen induced cracking resistance. The steel plate is suitable for use in a line pipe. The steel plate satisfies a predetermined composition. In a composition of an inclusion contained in the steel and having a width of 1 mum or more, the ratio (RES/CaS) of the mass of an REM sulfide (RES) to that of a Ca sulfide (CaS) is equal to or more than 0.05, a Zr content of the inclusion is in a range of 5 to 60%, and a Nb content of the inclusion is 5% or less.