Effect of Mo addition on as-cast microstructures and properties of grey cast irons

High performance cast iron (HPCI) with improved mechanical properties and tuned thermal conductivity is a strong candidate to replace ductile iron in the application of automobile components. Effect of Mo on as-cast microstructures and properties of the grey cast iron was investigated to clarify the roles of Mo element and possibility of developing HPCI through Mo addition. The results show that Mo addition leads to Mo micro-segregation as well as Mo2P and carbides precipitation in the grey cast irons. Mo addition can produce the chemical inhomogeneity and thus uneven graphite flake distribution in the alloys. The thermal expansion coefficient can be reduced by Mo addition. Lower Mo addition refines the majority of graphite flakes but increases the length of a small fraction of graphite flakes and consequently improves the thermal conductivity, while higher Mo addition induces to precipitation and solution strengthening thus enhances the UTS. Therefore, moderate Mo addition is an effective way to develop HPCI.