Numerical modeling and experimental investigation on the effect of rotation speed on microstructural evaluation and mechanical properties of copper during friction stir processing

Abstract

In the present work, the effect of different parameters of friction stir processing (FSP) on microstructure and mechanical properties of pure copper were investigated numerically and experimentally. Three different tool rotation speed (900, 1200 and 1500 rpm) and a constant traverse speed (60 mm/min) were used as FSP parameters. To model the microstructure of stir zone (SZ) which undergos the dynamic recrystallization (DRX) and grain growth, Zener-Hollomom parameter were used to predict the grain size. In the first step the temperature distribution was formulated and solved by a commercial software COMSOL Multiphysics. An analytical model were then utilized to calculate the strain rate distribution in SZ using MATLAB. Finally, strain rate and temperature were imposed to Zener-Hollomon equation to predict the grain size. The results of modeling indicated that by increasing the rotation speed, the Z parameters decreased and subsequently the grain size increased. The predicted grain size were in a good agreement with the experimental results. The mechanical properties also improved by grain refinement.