Research Article
Saliu Ojo Seidu, Adetunji Onig
Abstract
This study was undertaken to study the graphitization tendency with optimized properties for thin wall grey iron (TWGI) and predict the hardness and tensile properties by applying multivariate regression analysis. 0.3wt % addition of Ferrosilicon (FeSi) was used for the inoculation of different wall thickness of 2, 3, 4, 5, 6, 7, 8, 9 and 10 mm of the Grey Iron. The inoculation was done in the ladle and the different wall thickness was analyzed. The result reveals carbide and pearlite formation at the lower thickness. Graphitization and flakes distribution in the cast was evident from 6 mm wall thickness. Hardness and strength results also reveal the rapid disappearance of the carbide in ferrite microstructure of the thinner walls. Stability was found in the hardness properties analyzed at the point of graphite formation and flake distribution of the less thin walls. Regression analysis was carried out using the Origin Lab Pro software and MS Excel on the data obtained from the hardness and strength test. The prediction model for the thin wall properties were obtained using convergence multivariate regression analysis (heuristic method) through the generalized reduced gradient (GRG) function. The GRG function was employed to obtain the least sum of squares deviation using the prediction model. The model is used to predict the intermediate hardness/strength value between the experimented and non-experimented wall thickness which this research could not accommodate.