Ductile fracture behaviour of primary heat transport piping material

The fracture characteristics of pressure vessel materials must be understood well to implement leak-before-break concepts in the design of pressure vessels. For the construction of primary heat transport piping of Indian pressurised heavy water reactors, SA333 Grade 6 steel is
employed, and it is therefore important to understand the fracture behaviour of this steel. The present paper presents the ductile fracture characteristics of SA333 steel at elevated temperatures encompassing the service temperature of the steel, the fracture behaviour under
simulated seismic loading and the effect of variation of crack tip constraint on the fracture toughness of the material. Fractographic observations have been carried out to understand the origin of the high level of toughness of the material.