Fracture Toughness of Aged Stainless Steel Primary Piping Welds Evaluated by Multiple and Single-Specimen Methods

Fracture toughness testing was conducted on compact tension specimens cut from the Fast Flux Test Facility primary piping materials of 16-8-2 and 308 stainless steel welds aged at 427 and 482°C for 20,000 and 50,000 hr. The ductile fracture behavior of the materials was characterized at 205, 427, and 482°C using multiple and electric-potential single-specimen techniques. Electric-potential data were used to caculate crack extensions via an electric-potential calibration equation for the construction of J-R curves. Results demonstrate that the critical fracture-toughness values are in good agreement with those from the multiple-specimen method. Results showed that 20,000-hr aging caused more than 35 percent degradation in fracture resistance, and 50,000-hr aging resulted in a slight increase in J_c for 16-8-2 stainless steel welds. It was found that the fracture toughness levels of the primary piping after long-term aging were high and adequate at the aging temperatures and that fuel handling temperature, nonductile fracture was not expected to occur in these materials.