Optimization of Friction Stir Processing (FSP) Parameters for the Hardness and Wear Resistance Improvements Using Response Surface Methodology

In this research, the effect of different parameters in Friction Stir Processing (FSP) on hardness and wear resistance of Al2024 is investigated. For this reason, five levels are considered for the three main parameters including pin rotating speed, pin traveling speedand pin angle using response surface methodology. The maximum hardeness and minimum wear rates are considered as the responses for optimization. For evaluating the hardness (under the 300 gr loading) and wear behaviour of processed samples (under the 500 gr loading and 1000m sliding distance), ASTM -E384 standard micro-vikers hardness tests and ASTM-G99 standard pin on disk tests are used, respectively. For investigating the FSP effect on micro-structure, grain size and morphology, optical microscopy is used. The results show that pin rotating speed and traveling speed have directly effect on the average hardness and also have a second power index relation on it. Furthermore it is obvious that these two parameters have interaction on each other and able to study them separately. Pin angle parameter had not any effect on the average hardness approximately and also no interaction by other two parameters. After optimizing process, the optimized values for pin rotating speed, pin traveling speed and pin angle for the Al-2024 were 28mm/min, 1274 rpm and 2.5 degree, respectively. Hardness value and weight reduction in wear test for processed case in optimized case were 154 vikers and 9.3mg.