Creep deformation and damage mechanism of compact graphite cast iron with different pearlite contents

Abstract

The creep deformation and damage mechanism of compacted graphite cast iron (CGI) with varying pearlite contents were studied at 450 °C, 500 °C, and 550 °C, with accompanying stress ranges from 40 MPa to 150 MPa. The creep deformation of CGI alloys presents obvious when the temperature exceeds 450 °C. The creep rate exponentially decreases with pearlite contents and the creep mechanism changes from dislocation slip to grain boundary sliding. There are (Ⅰ) intergranular and transgranular cracks, (Ⅱ) interfacial debonding between graphite and matrix, and (Ⅲ) pearlite morphologic transforming in the microstructure of CGI during the creep test. (Ⅰ) and (Ⅱ) are mainly caused by the creep stress and temperature, and (Ⅲ) may be related to plastic deformation. These cracks can interact with each other and accelerate the failure and fracture of materials.