Fabrication of Hybrid Surface Composite of Aluminium Alloy using Friction Stir Processing Technique

Abstract

Friction Stir Processing (FSP) is a new process for producing aluminium alloy surface composites. Most composite fabrication processes modify the bulk of the material, whereas FSP simply changes the workpiece's surface properties while keeping the below-surface qualities the same as the parent material. The aluminium alloy AA5083 is noted for its outstanding performance in harsh environments. AA6061 is known for its good weldability and resistance towards corrosion. Due to their good mechanical properties they are used in heavy duty structures like truck frames, ships, Aerospace vehicles, Boilers, Motorboats and Rivets. Surface composite made using two kinds of reinforcement are known as hybrid surface composite, Al2O3 and B4C were used as ceramic particles while MWCNT were used as lubricant particles. AA6061-Al2O3/CNT hybrid surface composite showed 17.5% lower wear rate and 8% lower COF value than AA6061-B4C/CNT hybrid surface composite. Hybrid Surface Composites prepared using FSP increased hardness of base material up to 99 HV. Tool tilt angle from 1 to 3 degree was used on AA6061-Al2O3/CNT Hybrid Surface composite which were then tested for mechanical properties and wear characteristics. Results showed that hybrid surface composite produced using 1 degree of tool tilt angle and 2 passes of FSP showed higher hardness value of 78 HV but because of low material flow during the process lubricant phase particles were not distributed evenly and caused higher wear of 236 micron. Comparing all the results, composite produced by using 2 degree and 2 pass of FSP showed better overall results of 75 HV of hardness, lower rate of wear (153 micron) and 0.3577 value of COF.