Effect of Tool Velocity Ratio on Microstructural Characteristics of Friction Stir Processed Aluminium Based Metal Matrix Composite

Abstract

Stir casted aluminium (Al) based metal matrix composites (MMCs) have inferior properties due to uneven distribution of reinforcement particles. Friction stir processing (FSP) is used to overcome the uneven distribution of SiC particles in the Al matrix. The FSPed microstructure is significantly influenced by the process parameters used for processing. In FSP, the effect of tool velocity ratio (Tool rotation velocity/Tool travel velocity) on material flow, material mixing, material consolidation is predominant than other parameters. Hence a perfect combination of tool rotation speed and tool traverse speed is required to produce the surface modification. In this investigation the tool rotation speed is varied from 800 rpm to 1200 rpm while the tool rotation speed is maintained constant at 40 mm/min. The FSPed zones produced for different toolvelocity ratiowere subjected to micro structural characterization using optical microscope and SEM. From this investigation it is found that tool velocity ratio of 2.62 exhibited defect free stir zone with higher hardness compared to other ratios. The reasons for the above effects are discussed in detail in this paper.