Evaluation of dynamic fracture toughness on heavy wall ductile cast iron for container

Abstract

Dynamic fracture toughness of heavy wall ductile cast iron for container of spent nuclear fuel is evaluated mainly by the developed evaluation system, that is to say, CAI system (Computer Aided Instrumented Charpy Impact Testing System). The dynamic elastic-plastic fracture toughness value ( J d ) and the stable crack growth toughness value ( T mat ) are able to be estimated reasonably by this system. Furthermore, the β IC and impact response curve methods have been applied in transition temperature region and lower temperature one, respectively. As a result, it is clarified that these methods evaluate lower bound of dynamic fracture toughness in comparison with one obtained from conventional test method. By the way, elastic-plastic fracture toughness is generally affected by the specimen size. The valid condition for the specimen size determined under dynamic loading condition appears severer than that of ASTM E813. Constant J Id value is obtained by the specimen thickness of 20 mm (net specimen thickness 16 mm) in the side grooved Charpy type specimen.