The present work focuses on exploring an environmentally friendly solid-state spot welding technique known as friction stir extrusion (FSE) joining, commonly used for joining dissimilar sheet metals. The study aims to understand the dynamic behavior of FSE joints through shock tube experiments. Specifically, it employs the FSF method to join AA5052-H32 and SS304, both 1.5 mm thick. The investigation aims to evaluate the effect of spindle speed on fracture modes observed in lap shear tests and shock tube impact tests. It is observed that common fracture modes are observed in lap shear and shock tube impact tests and these occur randomly without any systematic consequence of spindle speed. The fracture modes also change during repeated experiments. Such results are applicable in the product design and estimation of process limits of joined structures in the automotive and aerospace industries.