FRACTURE TOUGHNESS OF AUSTEMPERED HIGH SILICON CAST STEEL

The influence of austempering treatment on the microstructure, retained austenite and fracture toughness of high silicon cast steel has been studied. The experimental results show that the retained austenite increases with increasing the austempering temperature, and the carbon contents in the retained austenite also shows a similar behavior. The fracture toughness of the steel firstly increases with increasing the austempering temperature, reaching a peak value of 63 MPa·m~(1/2) at about 360-385℃ and then decreases. The maximum fracture toughness can be obtained for this steel when the microstructure contains about 30%-35% retained austenite.