Experimental study was performed to evaluate the brittle crack arrest toughness value (Kca) and brittle crack arrest method of welded joint for EH40 grade steel. Steel plates with the thickness of 80mm were used and flux cored arc welding (FCAW) and combine welding (EGW+ FCAW) process were adopted to prepare the welded joints. Temperature gradient ESSO test was performed to measure the Kca of the welds. Also, constant temperature(-10°C) ESSO test was performed to establish of brittle crack arrest method using real structural specimens. In this study, it was aimed to investigate the effect of joint design and welding consumable on crack arrestability of thick steel plate using EH40 grade shipbuilding steel without block joint shift with 2 kinds of welding process.
Along with the rapid increase in the size of container ship, the steel plate used for ship hulls has been increased in thickness. The growing capacity of large scale ships such as containers is the cause of increase in the thickness and the strength of steel plates for shipbuilding (Yamaguch, 2005). Recently, shipbuilding companies have tried to use high strength ticker steel plates with yield strength 460MPa class in hatch side coaming of large container ship. A typical example of the strength deck construction of a large container ship is shown in Fig. 1. The toughness and the resistance to brittle fracture of steel plate tend to decrease for thicker plate which is so-called thickness effect (Nakano, 1992). Thicker steel plates are usually used for strength deck construction, including hatch side coaming, sheer strakes and longitudinal bulkheads of large container ships, because of the restrictions on designing hull girder strength for their large hatch openings. The 147th research committee of the Shipbuilding Research Association of Japan (SR147 committee, 1978) has performed the investigation on the crack arrest toughness of the high heat input welds with the thickness below 40mm.
