| Abstract: | Two aspects critical to the fracture behavior of three-wire stainless steel cladding were investigated by the Heavy-Section Steel Technology (HSST) Program: (1) radiation effects on cladding strength and toughness; and (2) the response of mechanically loaded, flawed structures in the presence of cladding (clad plate experiments).Postirradiation testing results show that, in the test temperature range from −125 to 288°C, the yield strength increased, and ductility insignificantly increased, while there was almost no change in ultimate tensile strength. All cladding exhibited ductile-to-brittle transition behavior during Charpy impact testing. Radiation damage decreased the Charpy upper-shelf energy by 15 to 20% and resulted in up to 28°C shifts of the Charpy impact transition temperature. Results of irradiated 12.5 mm-thick compact specimens (0.5TCS) show consistent decreases in the ductile fracture toughness, JIc, and the tearing modulus. Results from clad plate tests have shown that: (1) a tough surface layer composed of cladding and/or heat-affected zone has arrested running flaws under conditions where unclad plates have ruptured; and (2) the residual load-bearing capacity of clad plates with large subclad flaws significantly exceeded that of an unclad plate. |
