Ni-ADDED STEEL PLATE HAVING EXCELLENT TOUGHNESS SUCH THAT CHARPY TEST VALUES OF BOTH OF BASE MATERIAL AND WELDING JOINT AT -196°C ARE EACH 100 J OR MORE AND EXCELLENT PRODUCTIVITY, AND METHOD FOR MANUFACTURING THE SAME

PROBLEM TO BE SOLVED: To provide a steel plate of a 9% Ni-added steel which is extremely excellent in fracture resistance performance in a temperature range of about -196°C to -160°C and is also excellent in productivity, and to provide a method for manufacturing the same.SOLUTION: The Ni-added steel plate having excellent fracture resistance performance such that the Charpy test values of both of a base material and welding joint at -196°C are each 100 J or more and excellent productivity has a steel composition containing, by mass, 0.04-0.10% of C, 0.02-0.15% of Si, 0.3-1.0% of Mn, 0.0010-0.0100% of P, 0.0001-0.0035% of S, more than 7.5% and 10.0% or less of Ni, 0.01-0.08% of Al, 0.0001-0.0070% of N, and 0.0001-0.0050% of T-O, and the balance Fe with inevitable impurities. Further, the Ni-added steel plate is characterized in that the interface segregation concentration of P, in a part at a depth of 1/4 of the steel plate thickness in the steel plate thickness direction from the surface of the steel plate, is 0.1% or less. A method for manufacturing the steel plate is also provided.