STEEL PLATE HAVING YIELD STRENGHT OF 670 TO 870 N/nm² AND TENSILE STRENGHT OF 780 TO 940 N/nm²

摘要

In a steel plate according to the present invention, a chemical composition is within a predetermined range, an ± value is 0.13 to 1.0 mass%, a ² value is 8.45 to 15.2, an yield strength is 670 to 870 N/mm 2 , a tensile strength is 780 to 940 N/mm 2 , an average grain size at 1/2t of the steel plate is 35 µm or less, and a plate thickness is 25 to 200 mm. In the steel plate according to the present invention, in a case where SR is performed on the steel, a charpy absorbed energy at -40°C in an area in which SR is performed may be 100 J or more.