Effect of some inoculants on the structure and properties of thin wall ductile iron

Abstract

The production of ductile iron parts as thin as (2-3 mm), known generally as Thin Wall Ductile Iron (TWDI) casting. Inoculants play a great role in changing the structure–properties of ductile iron. In the present work, the effect of inoculation on thin wall ductile iron castings is analyzed. Three types of potent inoculants were used namely Ce-Ca-Al-S-O-FeSi, Zr-Mn-Ca-Al-Ba-FeSi and Sr-Al-Ca-FeSi. The in-mould inoculation was done. It is observed that Ce-Ca-Al-S-O-FeSi inoculant provides highest nodule count and a unique wide distribution of nodule size in comparison to thin wall ductile iron (TWDI) inoculated with Zr-Mn-Ca-Al-Ba-FeSi and Sr-Al-Ca-FeSi. By increasing the weight of Ce-Ca-Al-S-O-FeSi from 0.2% to 0.4% for in-mould inoculation leads to increase in the nodule count. It was also observed that thin wall ductile iron (TWDI) samples inoculated with Ce containing 0.2% to 0.4% inoculant contain pearlitic matrix, whereas the samples inoculated with 0.6% inoculant have ferritic matrix. The as-cast microstructure of thin wall ductile iron (TWDI) containing 0.6% inoculants contain islands of pearlite in ferritic matrix whereas the samples inoculated by 0.2% to 0.4% inoculants had ferrite in the form of concentric shells around graphite nodules.