Abstract

Compacted Graphite Iron (CGI) is a type of cast iron. Like others cast iron in general, Carbon Equivalent Value (CEV) is very influential on the morphology of CGI graphite. The ideal CEV is influenced by the thickness of the object had made before. The thickness of the object will affect time of the freezing process, the freezing rate is often represented by the value of the volume ratio with area of the object`s heat release or often called modules. The current standard only provides information that the CEV for CGI is 3.6 to 4.9 so further research is needed to get the optimal CEV on each thickness or module of the object. This research focused on the influence of CEV on certain thickness of 5 mm, 15 mm and 30 mm while the CEV used are 4.15, 4.31 and 4.36. The specimens with various thickness are then tested metallographically using an optical microscope and Scanning Electron Microscope (SEM) to see its effect on the formation of CGI graphite. The CEV of 4.36 results in an optimum amount of CGI graphite at a thickness of 5 mm by 50.5%, 15 mm at 55.1% and 30 mm at 64.2%. In this optimum condition, the CGI graphite that is formed has a good percentage of the number and value of shape criteria.

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