High-temperature deformation and interfacial damage in CGI: 3D numerical analysis

Compacted graphite iron (CGI), a type of cast iron, forms an integral part of the industry worldwide thanks to its good thermal and mechanical properties, excellent wear resistance, and competitive price. Despite the extensive research on cast irons since the 1950s, their thermomechanical behaviour and, especially, their fracture at the microscale is not yet fully understood. Interfacial debonding is the main mechanism of fracture in compacted graphite iron. Such features of interfacial-debonding initiation, thermal interfacial damage and deformation between graphite inclusions and a surrounding matrix are investigated in this work. A three-dimensional unit cell comprising the matrix and a graphite inclusion is developed to simulate thermal deformation and damage under pure thermal loading; both phases were assumed to have elastoplastic behaviours. Different fracture mechanisms were analysed under fully fixed and periodic boundary conditions. The results could provide a deeper understanding of the mechanisms of thermal deformation and fracture in compacted graphite iron.