Effect of tool traverse speed on high strength structural AA6092/17.5 SiCp-T6 AMC friction stir welding

Abstract

This study systematically explores the impact of Tool Traverse Speed (TTS) in Friction Stir Welding of aerospace-grade AA6092/17.5 SiCp-T6 Aluminium Matrix Composites. The TTS varied in the range of 0.5 to 3.5 mm/s with Tool Rotation Speed and Tool Tilt Angle being constant. Results indicate that the maximum peak temperature is achieved at 0.5 mm/s, gradually decreasing with increasing TTS up to 3.5 mm/s. Significant fluctuations in spindle torque and Z-force are observed, with values doubling between 0.5 mm/s and 3.5 mm/s TTS. Notably, both extremes of TTS exhibit significant tool wear. Examining the microstructure shows that as the TTS increases up to 2 mm/s, there is a reduction in the particle size while the particle density within the matrix rises. Hardness reaches its maximum at 2.75 mm/s, aligning with the best joint performance and impact resistance. Mechanical property evaluations show joint efficiency increasing from 62% at 0.5 mm/s to 90% at 2 mm/s, then decreasing to 60% at 3.5 mm/s TTS. Impact strength follows a similar trend, peaking at 20.7 J at 2.75 mm/s TTS. This study identifies the optimal TTS range of 1.25 mm/s to 2.75 mm/s, striking a balance between improved mechanical performance and microstructural refinement.