Abstract
The mesoscopic-structure related strength of graphite was investigated by using the microstructure-based fracture model. The model can treat mesoscopic grain and pore structures with the fracture mechanics as well as the statistical approach. In this study the model was applied to the prediction of tensile strength of the nuclear grade H-451 graphite. Input mesoscopic-structural parameters in the analysis were the grain size and pore size distribution. These parameters were determined by an image analysis with microstructural observation. From the analytical investigation following results are obtained: (1) The prediction by the microstructure-based fracture model had fairly good mean tensile strength as well as strength distribution. (2) Both experimental and predicted tensile strengths fitted in well with the Weibull statistical distribution. (3) The material with fine grain size had high tensile strength with large scatter, when the pore size is assumed to be constant. (4) The material with large pore deviation parameter had low tensile strength with large scatter, when the grain size is assumed to be constant.
