Size and Thickness Effects on the Ductile Fracture Toughness of a 316 L(N) Austenitic Stainless Steel in As-Received and Aged Conditions

Measuring ductile fracture toughness for materials requires the specimen size to be large enough for the tests to be valid. The presented work investigates the size related fracture behavior of as-received and aged 316 L(N) stainless steel through an experimental approach. It focuses on the effects of the thickness and size of the specimens on the evaluated toughness. Compact tension (CT) specimens (thicknesses from 4 to 50 mm) and double edge notched tensile (DENT) specimens (thicknesses from 2 to 5 mm) were used. At as-received state, CT tests lead to a nonmonotonic evolution of fracture toughness with a maximum at a critical thickness. At aged state, there is no significant thickness effect as all tests are valid. The essential work of fracture measured with DENT specimens appears to be equivalent to $J_{0.2}$ and consequently extends the nonmonotonic evolution of the fracture toughness at small thicknesses.