DEVELOPMENT OF OFFSHORE STRUCTURE STEELS AND WELDING MATERIALS FOR ULTRA LOW TEMPERATURE SERVICE: 2 - MECHANICAL PROPERTIES OF YP420MPa CLASS STEEL PLATES

摘要

The YP420MPa class steel plates for offshore structures in frigid sea areas such as Sakhalin were studied. Based on the IGF technology for enhancing HAZ toughness, the chemical composition of and the manufacturing processes for these steel plates were optimized. Consequently, we have succeeded in developing the YP420MPa class TMCP steel plates having a 75mm thickness, excellent HAZ toughness and good weldability. The welded joints of the steel plates, which were welded with heat inputs of 1kJ/mm, 5kJ/mm and 10kJ/mm, have CTOD values higher than 0.25mm at -50°C.