Microstructural features and mechanical properties of compacted graphite iron treated with calcium-magnesium based masteralloy

This paper presents some data on the microstructural features and mechanical properties of as-cast compacted graphite iron (CGI), produced through treatment with a special Ca-CaC₂-Mg masteralloy. Information on graphite morphology and matrix features, obtained using different numerical indices evaluated through a computer-based image-analyzing system and SEM observation of deep-etched specimens, shows that the graphite form is a mixture of ASTM types I, II, and III (compacted graphite), interspersed in a matrix with a 2:1 ratio of pearlite to ferrite. An average hardness (BHN) of 219, Charpy-V-Impact energy of 7.92 J, tensile strength of 354.5 MPa, and a corresponding elongation of 1.20% has been obtained for the as-cast iron. The fracture surfaces of tensile and room temperature impact tested specimens showed mixed modes of fracture.