Recently, there have been the increase of ship size and the development of oil and gas in arctic region. These trends have led to the requirements such as high strength, good toughness at low temperature and good weldability. On the other hand, there has been the key issue of crack arrestability in large size container ship. Steel plates with 80mm thickness were used and two welding processes, which are flux cored arc welding (FCAW) process only and combined welding process (EGW+FCAW), were used to produce full thickness weld joints. The effect of joint design on crack arrestability was investigated to prevent a catastrophic failure along the block joint of hatch side coaming. A brittle crack arrest technique was developed without block joint shift, using an arrest weld in the end of hatch side coaming weld line.
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. The size of container ship has been gradually increased for mass transportation and cost reduction in the shipping industry (Hsu, 2005). Thus, thick and high strength steel plates are used for the upper deck structure of container ship because of its large hatch openings (Yamaguchi, 2006). On the other hand, the susceptibility of brittle fracture of the shipbuilding steel tends to increase as the increase of steel thickness, which is so-called thickness effect (Nakano, 1992). So, classification societies such as NK, GL, ABS and KR require not only use of EH47 steel with a high fracture toughness but also preventing a catastrophic failure along the block joints of the upper deck structure in their EH47 rule guidance (NK, GL and ABS, 2009).