The effect of pulverized glass waste particle sizes on the mechanical properties of AA6061-T6 friction stir welded joints.

Abstract

Abstract The study sought to investigate the effect of pulverized glass waste (PGW) particle size as reinforcement for AA6061-T6 joints produced by Friction Stir Welding. The study utilized three particle sizes of 15 microns, 45 microns and 75 microns of the PGW as reinforcement alongside the established process parameters ranges of 900-1400rpm, 25-63mm/min and 1-2.5° in a Taguchi L9 orthogonal array for the welding process experimental design. The welding experiments were repeated for each reinforcement particle size mentioned above. Parallel-hole reinforcement strategy was used on all joints for the application of the PGW, Tensile strength, Hardness tests and Microstructural Analysis were carried out on the welded joints and subsequently, analysis of the data. For tensile strength, several sample sets showed a trend of higher tensile strength the smaller the PGW particles size (Figure 6). For hardness, however, there was no overall, discernable trend/pattern of increase in hardness as the particle size decreased. The highest average tensile strength value obtained was 85.25MPa. The lowest tensile strength was 14.26MPa. A distinguishing feature between the highest and lowest value for tensile strength is that the former was obtained with a traverse speed of 25 mm/min while the latter was obtained using a 40 mm/min traverse speed. The higher the rotational speed of the tool pin, the greater the heat of friction generated while the lower the traverse/welding speed, the greater the heat of friction generated as the tool pin spends enough time per unit length to generate sufficient heat and cause plastic deformation sufficiently high enough to cause grain refinement. Using imageJ, percentage distribution of PGW for each crucial zone (Nugget/Stir zone, Thermo mechanically affected zone and Heat affected zone) of the FSWed joint was generated for samples selected for microstructural analysis. The average value for each sample was obtained as well. The highest tensile strength value (85.25MPa) was obtained with a sample using the smallest PGW size (15 µm), in line with the trend (figure 6) in which tensile strength was greater the smaller the PGW size used. The highest hardness value (90.90 BHN) was obtained with the sample having the highest average value for percentage distribution of the PGW (58.06%). A distinct trend was noted in which the greater the percentage distribution of the PGW, the higher the hardness value obtained (figure 30).