Brittle crack-arrest fracture toughness in a high heat-input thick steel weld

Brittle crack-arrest fracture toughness (K_Ia) was determined as a function of the temperature in a large-scale (1 x 1 m) 50-mm thick steel base metal and its high heat-input (32 kJ/mm) weld. An impact initiates crack propagation from a notch at low temperature toward a higher temperature region where the crack stopped due to the improved fracture toughness. The relationship between the toughness and crack-arrest temperature provides the K_Ia at ?10 °C of about 100 MPa√m in the weld specimen, which is a significant decrease compared to that of the base metal (240 MPa√m). Furthermore, the path of the crack propagation was discussed in terms of the grain size, hardness, and Charpy impact energy of the localized crack region.