Simulation modeling and optimization of bitumen –palm kernel oil blend for austempering of cast iron and steel

Abstract

The study combines both simulation modeling and optimization of bitumen-palm kernel oil blend for austempering of cast iron and steel. Two independent factors namely austenitizing temperature (A) and holding time (H) were evaluated while five responses which includes ultimate tensile strength (u.t.s), hardness (h), impact strength (i), percentage elongation (e), percentage reduction in area (r.i.a) were evaluated. 3-D response surface and 2-D contour plots through response surface methods were used to estimate multi-response mathematical models. Desirability function approach provided by MINITAB 18 was used to determine the optimal settings of the response and factors after adequacy of the models to approximate the measured data had been established at 0.10 confidence level. From the result, optimum conditions for austenitizing temperature was 916.50C and 5 min while the predicted values of quenching hardness, ultimate tensile strength, impact strength, %elongation, %reduction in area were 1327.29MPa, 29.36J, 72.77%, 86.79% and 175.59HRC for 0.56%C-Steel; 1407.97MPa, 20.04J, 50.80%, 49.17% and 196.13 for 0.76%C-Steel; 1235.01MPa, 32.42J, 60.39%, 55.99% and 234.99HRC for ductile cast iron. Great improvement was seen in the steel performance after austempering process which gave rise to the conclusion that as the austempering time and holding time increases, that the mechanical properties of the steel were affected. Quenching of 0.56%C, 0.76%C-steel and ductile cast iron at the optimal settings using B-PKO saved one thousand naira (₦1000.00) showing 28.57% profit. The developed empirical models are recommended in some of the automobile and engineering industries during heat treatment operations so as to save time and energy.