Effect of friction stir welding process parameters on microstructure and mechanical properties of aluminum/polypropylene joint

In this research, the influence of friction stir welding parameters (tool traverse speed ranging from 50 to 150 mm/min, and tool rotational speed ranging from 300 to 1100 rpm) was investigated on the microstructure and mechanical properties of AA5052 aluminum/PP-Z30S polypropylene joint.Results showed that joint formation was accompanied by the formation of mechanical locks in the shape of anchor-like aluminum pieces.Decreasing the heat input (either by increasing the tool traverse speed or decreasing the tool rotational speed) resulted in the formation of larger anchors.The results of tensile-shear test showed that increasing the tool traverse speed from 50 to 100 mm/min led to an enhancement in the fracture load (by ~10%), while at higher traverse speeds, the fracture load decreased (from 235 to 181 N) due to the formation of defects and voids at the joint interface.An increase in the tool rotational speed from 300 to 900 rpm resulted in a superior fracture load (by 70%) due to the formation of anchors perpendicular to the polymer surface with greater penetration depth.