Effect of Hot and Cold Forging on Hardness, Tensile Strength and Microstructure of AI6061 Metal Matrix Composites Reinforced with Silicon Carbide Particles

摘要

In this research effect of hot and cold forging on hardness, tensile strength and microstructure of Al6061-MMC were analysed. Composite contains SiC particles with three different sizes ie 44μm, 63μm and 88μm varied at three different wt% (5%, 10%, and 15%) were fabricated using simple stir casting technique. Microstructure features of as-cast base alloy, as-cast composite and forged composites were examined using optical microscope. Effect of reinforcement size and wt% on hardness and tensile strength of both as-cast and forged composites were investigated and compared with base alloy. ANOVA (Analysis of Variance) was used to identify optimum conditions of reinforcement size and wt% required to achieve optimal mechanical properties. Microstructural observations revealed nearly uniform distribution of Al-Si alloy and SiC particles with interdendritic precipitates. Increase in wt% of SiC particles led to increase in hardness and tensile strength of MMC and led to decrease with further wt% addition. SEM was used to obtain fractographs of tensile specimens. Fracture mechanisms were analysed. Overall favourable properties were obtained in both hot and cold forged MMCs when compared to as-cast alloy and as-cast composite. Hot forged composite shows higher tensile strength and ductility compared to cold forged and as-cast composite.