| 摘要 |
The present invention provides a steel plate having demonstrably excellent hydrogen-induced cracking resistance and toughness. The steel plate is characterized in including, in percent by mass, 0.02-0.15% of C, 0.02-0.50% of Si, 0.6-2.0% of Mn, more than 0% and up to 0.030% of P, more than 0% and up to 0.003% of S, 0.010-0.08% of Al, 0.0003-0.0060% of Ca, 0.001-0.01% of N, and more than 0% and no more than 0.0045% of O, the balance comprising iron and unavoidable impurities; the mass ratio of Ca to S (Ca/S) being at least 2.0; the amounts of Ca, S, and O satisfying the equation (Ca-1.25 S)/O‰¤1.80; and the Ar gas content of the steel being no greater than 0.5 µL/cm 3 . |
