Effect of austempering process on tensile fracture morphology of Austempered Ductile Iron

The drawing shows SEM photos of tensile fracture morphology of Austempered Ductile Iron with different austempering process parameters. It can be seen from the figure that the fracture mode of austempered ductile iron obtained by isothermal transformation at 280 ℃ is quasi cleavage fracture At 320 ℃, in addition to the graphite pits formed by graphite shedding and the graphite balls exposed without falling off, more dimples around the graphite pits can be observed, and there are a few tearing edges, cleavage steps and river patterns, showing the mixed fracture characteristics of cleavage and micropore polymerization, which indicates that the fracture mode of austempered ductile iron is still accurate Cleavage fracture; when the isothermal transformation temperature rises to 380 ℃, the tearing shape around the graphite ball pit gradually weakens, and obvious cleavage steps and river patterns appear between the graphite balls, which indicates that the fracture mode of austempered ductile iron changes into cleavage fracture.

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