Simulation and Experimental Investigation of Friction Stir Welded Wrought Magnesium Alloy AZ31B

In this study, a finite element (FE) model was developed using the ANSYS software package to simulate the thermal behavior of a magnesium-based alloy during friction stir welding (FSW). The FE model was based upon a moving heat source, which was influenced by process parameters such as tool rotational speed, welding speed, shoulder diameter, and pin geometry. It was observed that the temperature increased with rotational speed and shoulder diameter but decreased with welding speed. The predicted maximum temperature distribution obtained from the FE model was validated by conducting experiments and using thermocouples to measure the actual temperatures. The absolute error percentage between the predicted and experimental values was less than 8%, indicating good agreement between the model predictions and the experimental data. The welded samples were tested for tensile strength, microhardness and impact strength. The maximum values obtained were 163.3 MPa for tensile strength, 4.1 KJ for impact strength, and 82 Hv for microhardness. Microstructural analysis revealed finer grains in the stir zone when using a welding speed of 150 mm/min, rotational speed of 900 rpm, and shoulder diameter of 19 mm. These parameters led to improved grain refinement in the welded region. Fractured surfaces from tensile tests were examined, and it was observed that the fracture initiation occurred in the thermomechanical affected zone of the advancing side.