Investigation of Isothermal Crack Arrest Test Procedure Consistent with K_(ca)： Development of Isothermal Crack Arrest Test Procedure 2

摘要

The hatch side structure in ultra large container ships is a key design to maintain bending stiffness of the whole ship structure with wide opened hatch in upper deck. Because brittle cracking in the hatch side structure will surely induce a catastrophic shipwreck, brittle crack arrest (BCA) steel prescribed in International Association of Classification Societies (IACS) must be applied for the hatch side members.IACS prescribed the unified requirement (UR) for brittle crack arrest design in 2013, and defines BCA steels with either brittle crack arrest toughness, Kca value or crack arrest temperature, so-called CAT. However, the prescription details of them in IACS UR are still different, because they are independently proposed by the different ship classification societies. The test procedure to evaluate Kca and the required Kca are already established in IACS UR, but no authorized CAT evaluation test has not yet established as well as no requirements in CAT for BCA steels.Considering the situation above, Japanese steel industry organized a workshop denoted as CAT Workshop to investigate brittle crack arrest toughness evaluation together with a Korean steel mill, POSCO in the last two years. CAT Workshop aimed to investigate a consistence of CAT with Kca as well as a development of CAT test procedure.In the present paper, the activity of CAT Workshop is reviewed. The CAT test procedure agreed in CAT Workshop is introduced with the discussed comments. The modification concept to keep a consistence of the CAT test results with Kca is also shown.