Abstract
Recent trends in shipbuilding and offshore industries are a huge increase in the ship size and the exploration and production of oil and natural gas in the arctic offshore region. High performance steel plates are required by these industrial trends. Also in IMO(International Maritime Organization) has begun to regulate of fuel of ship to environmental protection, therefore it is little bit difficult to use bunker-C oil to working ship. As the problem of environmental change such as global warming is emerged, the operation of the ship is considered to be involved in the environmental change problem, and the regulation of environmental pollution is gradually strengthened. As these environmental regulations are strengthened demand for LNG fuel ships is rapidly increasing. Currently, cryogenic steels used in LNG tanks include aluminum alloy, SUS 304, and 9%-Ni steel. Those steels are has high cost to construction of large LNG carrier. The new materials were suggested several steel mills to decrease construction cost and easy construction. The new cryogenic steel should be evaluate safety to applied real structure include LNG ship. Therefore, in this study, fracture toughness of weld joints were investigated with cryogenic steel for application of LNG tank.
