Production of ductile iron using ferrosilicon-magnesium master alloy in melt treatment is currently fraught with challenges bothering on cost and availability. In this study the suitability of cashew nut shells ash (CNSA) as a viable alternative to magnesium master alloys employed in the treatment of molten cast iron for enhanced mechanical properties was studied. The carbonized CNSA used varied from 2-10 wt. % to treat different heat batches; CA1-CA5 containing varied amount of CNSA, CaO and FeSi in the molten cast iron. The cast samples were subjected to both mechanical characterisation (tensile, hardness and impact) and microstructural analysis using Instron electromechanical machine, impact tester and scanning electron microscope (SEM) coupled with energy dispersive spectroscope (EDS). Results show that the 8 wt. % CNSA addition demonstrated the best mechanical properties comparable to ASTM A536 ferritic ductile cast iron. Specifically, the 8 wt. % CNSA cast samples exhibited 433 MPa tensile strength, 144HRC hardness and ductility of 14.7%. Contributions to improved mechanical properties may be attributed to the development of sufficient fractions of graphite nodules during melt treatment with CNSA. These outcomes are a boost both to the production of quality ductile irons and a cleaner environment. Keywords: Nodularisation, ductile-iron, cashew-nut, ferrosilicon-magnesium alloy, mechanical properties

Thin Wall Ductile Iron (TWDI) casting presents macroscopic and microscopic challenges using bentonite bonded moulding sand. In this study, moulding properties of bentonite, cassava starch and kaolin bonded silica sand were evaluated using various binder/sand formulations (6%, 9%, and 12%). TWDI samples of 3 mm thickness were cast using dry compression strength as criteria for each binder type. Cast samples were subjected to macroscopic, microscopic and Vickers hardness analysis. Kaolin bonded sand gave superior dry strength property of 650 KN/m 2 at 6 % addition. Samples showed nodularity and nodule counts of 96.2%, 587 nodules/mm 2 , 76.2%, 61 nodules/mm 2 and 96.5%, 985 nodules/mm 2 using kaolin, cassava starch and bentonite bonded sand respectively. Thickness deviations were observed in all samples, bentonite bonded samples being most significant. This study has shown that adopting kaolin as alternative binder for production of TWDI casting should be encouraged as properties of cast TWDIs samples were greatly improved. Keywords:Thin wall ductile iron (TWDI), binder/sand formulations, moulding sand properties, macroscopic and microscopic properties.