The fatigue strength of micro friction stir spot welding of AA1100 thin plate using different tools geometry

Micro friction stir spot welding (mFSSW) is one of the alternate welding techniques on a thin metal plate. This welding has several advantages compared to conventional welding. Some of its advantages include better quality welds and relatively low distortion. This study aims to determine the failure mode and the effect of tool geometry on the fatigue strength of the welds produced through the mFSSW welding technique using AA1100 thin plates. In this study, the varied parameter was the tool's geometry, divided into three types of tools where each tool has a different pin dimension: probeless, shoulder 450, and shoulder 650. A fatigue test was carried out to determine the resistance of the weld when the load is applied repeatedly from each tool geometry. Fatigue test results were processed and analyzed to make S-N diagrams. The study results show that the shoulder 650 tool produces the S-N diagram best fits the basic theory, and the error produced is the smallest among other tools. In addition, the failure mode generated from all test results in the nugget pullout failure type.