Joining 1.1- and 2.1-mm Al Sheets by Friction Stir Spot Welding

Abstract

This study used friction stir spot welding (FSSW) to weld 1.1- and 2.1-mm AA6061-T6 sheets at 560, 710, 900, and 1120 rpm at a fixed dwell duration of 5 s. It was determined how much heat was supplied into the FSSW, and the cycle temperature that occurred throughout the FSSW technique was carefully documented. Both the sheet metals and the formed FSSW weldments were subjected to micro and macrostructure analysis, as well as a lap shear test and a hardness test. A scanning electron microscope (SEM) was also used to study the cracked surfaces. A broad variety of rotation rates, ranging from 560 to 1120 rpm, were used to construct error-free spot joints, as shown by the macroanalysis. The microstructural results may show acceptable mechanical characteristics of FSSW joints, which pertain to the grain refinement of the joints’ stir zone (SZ). It was discovered that the optimal welding condition for establishing spot welds with varying thicknesses of thin sheets was 710 rpm. This was achieved with a SZ lap shear resistance of 5020 ± 20 N and hardness of 99 ± 2 HV₍₁₀₀₎. The temperature fluctuation and Von Mises stress distribution, in the AA6061-T6 FSSW sheets, were analysed by using ABAQUS/CAE 2021 software. The simulated peak temperature is rather similar to the recorded one. On the other hand, by raising the rotation speed, the peak temperature at the welded joints rose. The friction stir welding (FSW) procedures have an impact on the residual stresses; on the other hand, the welding parameters are influenced by the welding temperature and mixing.