Characterization, machinability studies, and multi-response optimization of AA 6082 hybrid metal matrix composite

Abstract

This work investigated the effect of carbonized eggshell and fly ash on the microstructure, mechanical properties, and machinability of AA 6082. The fabrication method selected for this study was stir casting. For the hybrid metal matrix composite, the weight fraction was 2.5wt% carbonized eggshell and 2.5wt% fly ash. Density analysis recorded a 10.66% reduction of the cast composite in comparison to the aluminum alloy. Improvements of 12.32%, 21.91%, and 8.30% were recorded for the microhardness, tensile strength, and compressive strength respectively. The wear studies of the cast samples revealed coefficients of friction (CoF) of 0.499 and 0.290 for the base metal and the composite respectively. For the machinability studies, the surface roughness and tool flank wear were the responses under consideration. The design of experiments was conducted using the Taguchi L₁₆ orthogonal array. The input parameters for this investigation were cutting speeds (100 mm/min, 200 mm/min, 300 mm/min, 400 mm/min), feeds (0.1 mm/rev, 0.2 mm/rev, 0.3 mm/rev, 0.4 mm/rev), and depths of cut (0.25 mm, 0.50 mm, 0.75 mm, 1.0 mm). For the multi-response optimization, Taguchi-based grey relational analysis was used. The analysis of variance (ANOVA) of the grey relational grade (GRG) revealed that the feed was the most influential factor on the GRG. The initial optimization showed the optimal cutting speed, feed, and depth of cut as 100 mm/min, 0.1 mm/rev, and 0.25 mm respectively. The confirmatory tests revealed that the optimal combination of factors was 400mm/min, 0.1 mm/rev, and 0.25 mm for the cutting speed, feed, and depth of cut respectively.