Abstract
In order to simulate fracture behavior of nuclear fusion first wall by electromagnetic force, 4-point-loading test was conducted and mode III fracture toughness of SM490 and its welded joint was evaluated. The mode III fracture toughness of fusion zone was lowest while the resistance against crack extension was relatively high for weldment and fusion zone. In these, the friction of crack faces by slight crack curving or rough fracture surface contributes to high resistance. In all specimen, the fracture surface was occupied by inclined-elongated-dimple though crack extension by shear force was eminent near specimen surface.
