Evaluation of Machinability of Austempered Spheroidal Graphite Cast Iron for Continuous Casting

The machinability of austempered spheroidal graphite cast iron made by continuous casting (A-FCD600) was investigated. In this study, spheroidal graphite cast iron made by continuous casting (FCD600) was used to examine the influence of the austempering on machinability. In addition, austempered gray cast iron made by continuous casting (FC250) was used to examine the influence of the morphology of graphite on machinability. From the results of a tool wear test using continuous turning, the machinability decreased in the order of FC600, A-FC250 and A-FCD600. When relative machinability ratings between each material were calculated using tool life equations decided by the result of the tool wear test, the machinability of A-FCD600 was approximately 1.9 times inferior to FCD600, and approximately 1.3 times inferior to A-FC250. One characteristic of A-FCD600 was that its mechanical properties were relatively near steel. Therefore, a similar tool wear test was carried out with a P10 cemented carbide tool for steel. In this case, the tool life extended 25% compared to the K10 cemented carbide tool for cast iron. These results suggest that tool life can be improved in A-FCD600 cutting when tools for steel are used.