A review of the ESB small punch test data on various plant components with special emphasis on fractographic details

Abstract The present paper was aimed at reporting the experience within the ESB regarding small punch testing of various plant components including steam drums, rotors and turbine bolts. It was shown that a reasonable relationship existed between the Charpy FATT and the small punch transition temperature, TSP. The TSP value coincided with a small punch energy level of some 0.75 J while the upper and lower shelf energies were 1.2 and 0.2 J, respectively. A detailed fractographic study revealed that the upper and lower shelf regions corresponded to fully ductile and brittle failure respectively. Furthermore, the extent of ductile fracture increased with temperature. Indeed, is was found that the TSP value corresponded with around 25% ductile fracture and a ductile crack depth of some 120 μm. A reasonable relationship was shown to exist between the Charpy FATT and the small punch energy value at liquid nitrogen temperatures.