Wear behavior of boron-carbide reinforced aluminum surface composites fabricated by Friction Stir Processing

The present study aims to investigate the wear behavior of boron-carbide (B4C) reinforced aluminum surface composites fabricated using Friction Stir Processing (FSP). Al-6061-T6 was used as base-metal and B4C particles (800 mesh) were used as reinforcement media. Two specimens with 1-capping-pass and 3-stirring-passes were prepared. In specimen-1, the direction of consecutive processing passes were same. In specimen-2 the sample was rotated by 180 degrees between consecutive processing passes, thus the direction of processing passes was reversed. Wear analysis of the specimens was done using Pin-on-Disc wear testing (ASTM-G99 standard) supported by scanning-electron microscopy (SEM), micro-hardness data and microstructural characterization. Wear testing was also done for as-received Al-6061-T6. Three samples each for base-metal, specimen-1 and specimen-2 were subjected to wear testing which was done as per guidelines stated in ASTM G99 for pin-on-disk wear testing. Specimen-1 showed 72.15% less wear as compared to base-metal, whereas specimen-2 showed 74.82% less wear as compared to base-metal and 9.58% less wear as compared to specimen-1. The reduction in wear can be attributed to the refinement and homogeneous distribution of the reinforcement particles in the base-metal. The distribution of particles is evident from SEM. Reversal of direction of processing passes further enhances the refinement and distribution of reinforcement particles. Wear is reported in volume loss and standard error for the wear test was 1.315 mm(3) for base metal, 0.301 mm(3) for specimen-1 and 0.111 mm(3) for specimen-2, indicating that the wear behavior of surface composites is highly repeatable, with repeatability of specimen-2 being better than specimen-1. Higher repeatability indicates uniform distribution of reinforcement particles in the base metal.