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Stir casting is employed for successful casting of aluminum-based metal matrix composite (MMC) plates of 12 mm thickness. Surface imperfections, porosity and reinforcement agglomeration are the main concerns in stir casting processes. Solid state friction stir processing (FSP) enhances mechanical characteristics by grain refinement and uniform distribution of reinforcement of MMC. Some of the crucial specifications of FSP include the tool traverse speed, tool rotational speed, tool shoulder diameter (D/d) ratio, pin design, pin length and axial force. In this investigation, five varying tool traverse speeds ranging between 20 mm and 60 mm per min were experimented on the stir cast plates. The wear rate, microstructure and microhardness evaluation on FSP plates revealed that wear resistance of 40 mm/min tool traverse speed FSP plate is superior and attribute to significant microhardness values. In addition, fine grains, uniform distribution and SiC particle bonding with aluminum matrix contribute to effective resistance to wear.

Friction stir processing is demonstrated to effectively enhance the surface and bulk properties of aluminum composites fabricated via the stir casting route. This process is performed below the melting point of the base material wherein common conventional fabrication problems such as solidification, liquidation cracking, and porosity are eliminated to a significant extent. Five different tools with varying tool diameter ratios are experimented on while maintaining tool rotational and traverse speeds and axial force constant. In this investigation, the hardness and wear characteristics of the LM25 aluminum alloy reinforced with 5% silicon carbide particles composite is studied. It is concluded that the tool with a tool diameter ratio of 3.0 resulted in a defect-free processing zone, refined grains, and a minimum particle size enhancing the wear resistance and hardness as compared to that for other values of a tool diameter ratio.

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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.

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In friction stir processing (FSP), tool rotational speed (TRS) and tool traverse speed (TTS) are the two important parameters, known to produce significant changes in the properties of the processed material. Increasing the TRS and TTS beyond a certain level would produce undesirable results. The heat generation will increase with an increase in the TRS and decrease in TTS. Excessive heat generation results in the formation of coarse grains exhibiting poor mechanical properties. The heat generation will decrease with decrease in the TRS and increase in TTS. Low heat generation will lead to inadequate plasticization and improper material flow. Hence a perfect combination of TRS and TTS is required to attain desirable properties in FSPed material. In this investigation FSP was carried out on aluminum based metal matrix composite (LM25AA+5%SiCp) material using five different tool velocity ratios (TVR: TRS/TTS). The FSP was subjected to microstructural characterization and tensile properties, evaluation. The results revealed that the TVR of 2.6 yielded superior tensile properties compared to other conditions.