Numerical and experimental investigation on FSSW of Al alloy to steel using an embedded rod tool

In this study, the embedded rod tool was used to conduct Friction Stir Spot Welding (FSSW), and numerical modeling was established to simulate this process, based on the experimental records of downward force and plunge depth. In this modeling, the relative speed between the workpiece and the tool was predicted by experimental and numerical methods. To verify this model, the friction coefficient for the Al alloy self-mated pair was obtained in the FSSW of the Al alloy, by comparing the measured and computed temperatures. Furthermore, the friction coefficient of Al alloy/steel was obtained in the same method and results. For the FSSW of the Al alloy on steel, the numerical and experimental results showed that higher tool speed leads to a higher plastic flow speed and temperature. When the temperature at the faying surface was higher than 460 degrees C, good bonding was obtained on the surfaces between the Al alloy and the steel.