Reproducibility of pop-in using heterogeneous welded joint specimen and cohesive surface model

When a pop-in as a phenomenon of initiation, propagation, and arrest of a brittle crack occurs in the fracture toughness test, the fracture toughness may be evaluated extremely low. In order to identify the cause of pop-in occurrence, an objective of this study was to demonstrate pop-ins in the three-point bend fracture toughness tests. It was possible to reproduce pop-ins at LBZ zone by preparing the specimens containing heterogeneous weld metals and considering the temperature dependency of the toughness in each welding material. Furthermore, the pop-in occurrence could be simulated by finite element analysis using a cohesive surface.