ISSUE 4/2014

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Lampic, M.; Koch, F.; Walz, M. A novel scientific approach to vermicular (compacted graphite) cast iron as per DIN EN 16079  Part 1: Definition, history, production, CGI as a “green“ material

Cast iron with compacted (vermicular) graphite – cast iron with vermicular graphite – is standardized as CGI since 1985 in ASTM A-842, and as JV since 2006 in ISO 16112 and finally in 2011as GJV with DIN EN 16079. Both, the ISO and DIN standard are substantially based on the VDG instructions W50, revised in 2002. The morphology of vermicular graphite is best described in comparing it with a coral reef. Its position “between” the flaky and nodular graphite is confirmed by the solidification curves of these materials, already indicating the ability of GJV to combine in some extend the properties of GJL and GJS. On the other hand, the “tuning” of the base curve to reach the desired curve shape had become the most used control means in the production of GJV (CGI). Probably the most important property of GJV is its excellent castability, enabling it to achieve high strength thin section castings, as shown with the legendary V6-cylinder block of the Opel Race-Calibra engine, of 1994 and 1995, where the weigt-to-power ratio was quartered in comparison to the regular engine. For the energy saving potential this fact almost alone makes GJV to a “green material”.

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