Comparison of crack-arrest fracture toughness between low and high heat-input thick weld specimens

Brittle crack-arrest fracture toughness $$(\hbox {K}_{\mathrm{Ia}})$$ was determined in low (1.5 kJ/mm) and high (53 kJ/mm) heat-input weld specimens with a large scale ( $$1\times 1$$ m) and thickness (50 and 80 mm). An instant impact having energy of 2.7 kJ was imposed into the full-thickness notch tip at low temperature and initiates crack propagation 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 $$\hbox {K}_{\mathrm{Ia}}$$ at $${-}10\,^\circ \hbox {C}$$ of about 2700 and $$2200\,\hbox {N/mm}^3/2$$ in the low and high heat-input weld specimens, respectively. This discrepancy was correlated to the grain size and Charpy impact energy of the notch region caused by the amounts of heat inputs in each weld specimen.