An elasto-plastic theory of fracture and its application to the analysis of experimental data

The fracture analysis of a steel reactor vessel requires a knowledge of the fracture resistance of the steel and a method of relating this to stress levels and critical crack sizes. The requirement for a high level of integrity against fast fracture leads to the selection of materials for this application, which present problems of fracture toughness measurement at operational temperatures. This paper, after describing a theory suitable for application under these conditions and its relationship to other basic methods such as LEFM, compares theoretical predictions with experimental data for A533B Cl 1 steel plate for temperatures in the brittle to ductile transition range. By means of an empirical correlation based on a number of tests on other steels, relating fracture resistance to Charpy values and tensile properties, the critical conditions for onset of fast fracture over the complete temperature range of interest for the reactor pressure vessel steel, are defined. (author)