Investigation of mechanical properties and electrical discharge machining of LM25-RHA metal matrix composite

Abstract

In this work, the effect of weight percentage of rice husk ash (RHA) on mechanical properties and machinability of LM25 alloy of aluminium has been investigated. RHA has been mixed with the LM25 alloy by 4%, 6%, 8%, and 12% and aluminium metal composite (AMC) has been prepared by two-step stir casting process. The tensile strength, compressive strength, wear strength, hardness and optical microscopy examination have been done in order to characterise the AMC. Composite prepared. Further, the machinability has been investigated by conducting experiments on electrical discharge machining (EDM). The experiments have been conducted on Taguchi's L9 orthogonal array, the parameters being weight percentage (wt%), pulse current (Ip), pulse on time (Ton), and gap voltage (V) and the responses are material removal rate (MRR), tool wear rate (TWR), and surface roughness (Ra). The result reveals that the tensile, compressive, wear strength and hardness has increased sharply by increasing the reinforcing RHA. Further, Ip is significant parameter for MRR which shows an increasing trend with the pulse current, similar observation has seen with TWR, while Ra has increased by varying percentages of RHA from 4% to 12%. The microstructure examination through an optical microscope shows the uniform distribution of RHA into the base alloy with some casting defects.