Factorial Analysis of Al-Si-Mg Alloy Cast Hardness Based on Thickness and Ultimate Tensile Strength [ READ ]
C. P. Egole, G.C. Nzebuka, U.S. Ikele, M.I. Chikwue
Factorial analysis of the hardness of Al-Si-Mg alloy cast was carried out based on its thickness and ultimate tensile strength (UTS). A two-factorial empirical model was derived, validated and used for the analysis. The derived model showed that the hardness of the Al-Si-Mg alloy cast is a linear function of its thickness and UTS. The validity of the derived model expressed as: ξ = 0.19 ϑ + 0.0003ɤ + 46.0 was rooted on the model core expression ξ - 0.0003ɤ = 0.19ϑ + 46.0 where both sides of the expression are correspondingly approximately equal. Evaluations from generated results indicated that the standard error incurred in predicting the hardness of Al-Si-Mg alloy cast for each value of its thickness & UTS considered, as obtained from experiment and derived model were 0.5497 and 4.8667 x 10-8% & 0.4463 and 0.8758 % respectively. The hardness of Al-Si-Mg alloy cast per unit thickness & UTS as obtained from experiment and derived model results are 0.1857 and 0.19 HRB /mm & 0.2128 and 0.2177 HRB/ Nmm-2, respectively and the correlations with thickness & UTS were all > 0.95. Deviational analysis shows that the maximum deviation of model-predicted hardness of Al-Si-Mg alloy cast from the experimental results is less than 2%. These invariably translated into over 98% operational confidence for the derived model as well as over 0.98 reliability response coefficients of Al-Si-Mg alloy cast hardness to its thickness & UTS.
C. P. Egole, G.C. Nzebuka, U.S. Ikele, M.I. Chikwue
Factorial analysis of the hardness of Al-Si-Mg alloy cast was carried out based on its thickness and ultimate tensile strength (UTS). A two-factorial empirical model was derived, validated and used for the analysis. The derived model showed that the hardness of the Al-Si-Mg alloy cast is a linear function of its thickness and UTS. The validity of the derived model expressed as: ξ = 0.19 ϑ + 0.0003ɤ + 46.0 was rooted on the model core expression ξ - 0.0003ɤ = 0.19ϑ + 46.0 where both sides of the expression are correspondingly approximately equal. Evaluations from generated results indicated that the standard error incurred in predicting the hardness of Al-Si-Mg alloy cast for each value of its thickness & UTS considered, as obtained from experiment and derived model were 0.5497 and 4.8667 x 10-8% & 0.4463 and 0.8758 % respectively. The hardness of Al-Si-Mg alloy cast per unit thickness & UTS as obtained from experiment and derived model results are 0.1857 and 0.19 HRB /mm & 0.2128 and 0.2177 HRB/ Nmm-2, respectively and the correlations with thickness & UTS were all > 0.95. Deviational analysis shows that the maximum deviation of model-predicted hardness of Al-Si-Mg alloy cast from the experimental results is less than 2%. These invariably translated into over 98% operational confidence for the derived model as well as over 0.98 reliability response coefficients of Al-Si-Mg alloy cast hardness to its thickness & UTS.
