Effect of cyclic heating on ductility deterioration of high silicon ferritic spheroidal graphite cast iron by salt bath

Abstract

Severe ductility deterioration will be caused when the ferritic spheroidal graphite cast iron undergoes a certain number of heating and cooling cycles. A greater ductility drop resulting from intergranular fracture will be induced when the specimens are cyclic heated in a chloride-rich atmosphere; however, the tensile elongation tended to decrease as the number of heating cycles increased. This significant phenomenon including the ductility deterioration rate of the salt bath heated specimen is higher and the fracture surface of SG cast iron tended to transit from a brittle cleavage fracture to an intergranular fracture as the number of thermal cycles increased. Fractography can confirm that the intergranular crack mainly initiated and propagated at the solidificational eutectic cell wall region, owing to a significant amount of Mg containing inclusion particles clustering at the eutectic cell wall. In addition, crack initiation and propagation will be promoted as a result of the chloride reaction from the surface. IJCMR/427