The figure shows the secondary electron image of tensile fracture of Austempered Ductile Iron with different wall thickness treated at 920 ℃ / 2H + 280 ℃ / 1.5h. It can be found from the figure that the tensile fracture morphology of Austempered Ductile Iron with casting wall thickness δ = 17cm appears obvious fluctuation, and the fluctuation degree gradually decreases with the decrease of δ. At the same time, when δ = 7 cm, 12 cm and 17 cm The results show that the fracture mode of austempered ductile iron is quasi solution, except for the graphite pits formed by graphite shedding and the exposed graphite balls without falling off, a small number of dimples can be found near the graphite pits, and there are tear edges, dissociation steps and river patterns between the graphite pits, which indicates that the fracture mode of austempered ductile iron is quasi solution Fracture.
