| 摘要 |
The present invention provides a thick hot rolled steel plate having excellent resistance to hydrogen induced crack and sulfide compound stress crack, comprising: 0.02-0.05 wt% of C, 0.05-0.5 wt% of Si, 0.5-1.4 wt% of Mn, 0.01 wt% or less of P (excluding 0 wt%), 0.001 wt% or less of S (excluding 0 wt%), 0.02-0.05 wt% of Al, 0.01-0.07 wt% of Nb, 0.005-0.02 wt% of Ti, 0.002-0.008 wt% of N, 0.01-0.5 wt% of Cr, 0.01-0.5 wt% of Mo, 0.0015-0.003 wt% of Ca, the remaining consisting of Fe and inevitable impurities; and satisfies a condition of 1 <= Cr/Mo <= 5. A fine structure thereof includes 2 area% or less of pearlite, and 0.5 area% or less of MA. Also, the thick hot rolled steel has a non-metallic inclusion of 50 or less per 100x50 mm^2 which has an average size equal to or greater than 20 μm. |
