On stress propagation and fracture in compacted graphite iron

In this work, initiation and propagation of fracture in compacted graphite iron (CGI) has been investigated and modeled under the dynamic loading scenario. Fracture initiation was found to originate at the graphite particles and at graphite/matrix interface at no particular preference of order and propagated into the metal matrix in the form of a network of microcracks which eventually coalesced leading to complete failure of the material. Metallurgical investigations of fracture in CGI under both quasi-static and quasi-dynamic tests were comprehensively implemented. Investigation of stress concentration propagation at specific fracture propensity regions have been modeled and simulated on a real CGI sample RVE using commercial finite element package, ABAQUS (TM)/CAE (TM) v6.9. The CGI sample consisted of > 90% pearlite matrix. Furthermore, FE modeling allowed the observation of stress concentration initiation and propagation at the CGI graphite particles and graphite-matrix interfaces until fracture. Crack bluntness was observed in the model and a change in the potential crack path was visual. Several findings were documented in an effort to better understand the behavior of CGI under quasi-static and dynamic conditions. This work is a milestone among a series of successive tasks all aiming to better understand, validate, and build a yet unavailable comprehensive model of CGI behavior under diverse loading schemes.