Effect of Small Amount SiC on Mechanical Properties Composite Fabricated by Casting and Subsequent Rolling Process

Abstract

Aluminum matrix composites (AMCs) are promising material to develope for engineering application in last a few decade. Combination between aluminum matrix and reinforced particles was succesfull increase the mechanical properties. Casting method have been used to fabricate the AMCs due to their simple process and low cost, however the nonuniform distribution elements and some defects were often observed in the microstructure by this traditional casting process. Furthermore, these problems have influenced the mechanical properties of composites. In other hand, the thermomechanical treatment and dispertion strengthening by particles such SiC are attractive technique to improved mechanical properties of composite such AMCs. Thermomechanical such rolling process was successfully modified the properties of composite, high energy from rolling machine induced plastic deformation and grain refinement of microstructure. The modification of this microstructure is the important role to enhance the mechanical properties. The aim of this research to investigate the effect of rolling process on microstructure and mechanical properties of aluminum cast reinforced with SiC particles. In the current work, Al-Si alloy ingot used as a matrix and reinforced with SiC particles for different composition (1.5, 2.0, 2.5 wt.%). Remelted ingot and SiC have been done in crucible grafite to prevent from contaminant. Composites material were fabricated by using pressure casting at 35 MPa, 657°C pouring temperature and the permanent mold made from mild steel with holding temperature 300°C. Further, a hot rolling process was performed at 550°C with 20% thickness reduction through multi pass process to obtain the thickess of sheets. The microstructure of composites were investigated by optical microscope (OM) with different magnification. Brinell hardness test was carried out to obtained the hardness on the surface of composites rolled. The impact test was conducted in room temperature by using charpy model. Furthermore, the ultimate tensile strength of composites were perfomed by universal tensile machine. The results shows the increase of SiC particles upto 2.5 wt.% promoted the finer microstructure was observed after rolled. Further, the sligthly increase both of hardness and tensile strength have been achieved after hot rolling with different silicone particle. The maximum hardness 71 HB of composite rolled was obtained for 2.5 wt.% SiC. The impact strength 19 joule was observed in 2.0 wt.% SiC and sligthly decrease with the increasing of silicone carbide. In other hand, the ultimate tensile strength 130 MPa was obtained for 2.5 wt.% SiC, the addition of a small amount SiC promote a slightly change the mechanical properties.