Effect of Addition of Inoculants and Solidification Structure on Machinability in Flake Graphite Cast Iron

Abstract

The relationship between machinability, addition of inoculants and solidification structure has been investigated by measurement of cooling curves, observation of microstructures and cutting tests for FC250 flake graphite cast irons which have different morphology of graphite and matrix structure fabricated by Fe-Si and C-series inoculants. The D-type graphite has been observed in the Base (inoculant-free) alloy, and A-type graphite appeared in alloys which have included higher contents of inoculants. The width of flank wear of each alloy was decreased with increasing of cutting force, while the cutting temperature was increased with increasing of cutting force. The width of flank wear of each alloy has been also increased with increasing of area fractions of graphite and ferrite, although the width of flank wear has been decreased with increasing of area fractions of perlite. The surface of flank of Al 2 O 3 coated tool has been observed by scanning electron microscope (SEM), and some compounds including Si was confirmed on that surface. Those compounds probably are formed during cutting, and wear of cutting tool has been accelerated, even in the case of low cutting force.