The Effect of Different Grain Refiners on Microstructure and Mechanical Properties of Thin Ductile Castings

In the present study the influence of different kinds of grain refiners on microstructure, mechanical properties of thin ductile castings have been investigated. Three grain refiners that have been used are pure ferro-silicon, Fe-Si-Sr, and Fe-Si-Zr at 0.1%(wt) and samples were strips with different thicknesses from 0.3 to 4 mm. Chemical composition of the melt was 3.3%C, 3.62%Si, 0.22 Mn,and 0.032%Mg with CE=4.5% and pouring temperature 1400 ○C. Microstructures have been investigated by Optical Microscopy. The results of mechanical properties and microstructure analysis show, samples that are grain refined with pure Fe-Si have not enough nodularity comparing with two other grain refiners and Fe-Si Sr had better effect on reduction of micro-shrinkage, chill depth, carbide forming and had higher mechanical properties. In Si-Fe-Sr grian refined samples UTS was 15% higher and elongation rised from 1.25% to 3% and also comparing with Fe-Si-Zr in samples with 1mm thickness micro-shrinkages were smaller