Effect of filtration on the microstructure and properties of as-cast ferritic nodular iron

Three kinds of filters were used in the production of as-cast ferritic nodular iron specimens. The authors investigated the differences of microstructure and mechanical properties between filtered and unfiltered specimens. The results showed that after filtration the graphite nodules got finer and more regular, the pearlite percentage reduced; and the elongation fatigue ratio and impact values at different temperatures were significantly improved without obvious change in tensile strength. The more effective the filter was, the higher the plasticity and toughness of iron was. The ceramic foam filter was better than the extruded cellular filter while the sieve core had a poor filtration effect.