Friction stir processing for tensile strength and microstructure enhancement of Lm25 aluminum alloy – 5% Sicp metal matrix composites

Abstract

The stir casting method is used to make metal matrix composites and fabricated into plates. The composite material suffers from porosity, uneven distribution of reinforcement particle, and friction stir processing (FSP) is attempted to improve the surface properties of LM25AA-5% SiCp aluminum based metal matrix composite. Tool rotational speed is one of the vital FSP parameters which will influence the processing efficiency predominantly. In this investigation, five different tool rotational speeds of 800, 900, 1000, 1100 and 1200 rpm were used and their effect on tensile strength, microstructure, hardness and ductility of the friction stir processed material were evaluated. From this investigation it is found that the tool rotation speed of 1000 rpm yielded superior tensile strength compared to its counterparts. The formation of finer grains in the stir zone and uniform distribution of reinforcement particles are the main reasons for the superior tensile properties of this material.