Wear behavior of Al-6061-B4C surface composites fabricated by Friction Stir Processing using Slot and Hole method of reinforcement application

Friction stir processing (FSP) has garnered the interests of many researchers for developing surface composites. The current investigation aims at understanding the effect of method of reinforcement (B4C powder) application during FSP on wear behavior of Al-6061 T6 alloy. The reinforcement media is placed in a narrow (2 mm x 2 mm x 100 mm) blind slot before processing in the Slot method. The reinforcement media is placed in an array of zigzag holes (phi 2 mm x 2 mm deep) before processing in the Hole method. FSP is done on the specimen plates to develop the surface composites. Specimens with varying number of passes (1, 2 and 3) and direction reversal are prepared for both the method viz. the Slot method and the Hole method. Pin-on-disk wear testing is performed as per ASTM G99 for all the specimens. The effect of FSP is to refine and uniformly distribute the reinforcement media in the base metal (Al-6061). The best specimen prepared using slot method showed a 86.14% reduction in wear as compared to the base-metal and that using hole method showed a 87.43% reduction in wear as compared to the base metal. The specimens prepared using the Hole method show superior wear resistance as compared to the specimens prepared using the Slot method. The same is attributed to more enhanced refinement and distribution of the reinforcement media in the base metal matrix for the Hole method. The wear results are supported by microstructural characterization and micro-hardness characterization along with the volume fraction and particle-size distribution of the reinforcement media for all the specimens.