Fracture properties of ferritic, ferritic- pearlitic, pearlitic and bainitic nodular cast irons

The use of nodular cast irons in components having high safety requirements has increased rapidly during last years. Casting permits a design where the stress concentrations are minimised and the cast material itself has shown to have good mechanical properties which can be obtained repeatedly. Although the conventional mechanical properties of nodular cast irons are well defined, the fracture behaviour is not because the fracture toughness and fatigue property data have until now been scarce. In this work different nodular cast irons were tested in order to investigate the thickness and temperature effects on the fracture toughness parameters KQ, delta and JIc . The fatigue parameters C, m and DELTA Kth were also examined. Although the microstructure forms the basis of the fracture behaviour of nodular cast irons, it was found that some deviations in fracture properties reported in the literature are due to insufficient testing conditions.