STEEL FOR WELDED STRUCTURE EXCELLENT IN LOW TEMPERATURE TOUGHNESS OF HEAT AFFECTED ZONE OF WELDED PART, AND METHOD FOR PRODUCTION THEREOF

摘要

The present invention is the low temperature toughness of the HAZ, and weldability can be manufactured at low cost without using a complicated recipe to provide excellent high strength thick steel plate for a marine structure and its manufacturing method in mass%, C: 0.03 to 0.12%, Si: 0.05 to 0.30%, Mn: 1.2 to 3.0%, P: less than 0.015%, S: 0.001 to 0.015%, Cu + Ni: less than 0.10%, Al: 0.001 to 0.050%, Ti: 0.005 to 0.030%, Nb: 0.005 to 0.10%, N: a steel containing 0.0025 to 0.0060%, the cast by the continuous casting process, and , the cooling rate of 0.06 to 800 from the vicinity of the freezing point of the secondary cooling then to 0.6 / after obtaining a cast piece in a hot rolling, and s, 800 characterized in that the cooling from a temperature above the welding heat affected zone This is an excellent low-temperature toughness weldable steel recipe.