Initial ultimate tensile loads at first glance seem higher than the base material of Aluminum 6061 which has yield strength of 276 MPa. This is due to the fact that the overall strength of the two-sided FSR by extrusion joint is a complex combination of forces and interactions of both a mechanical and chemical nature and not just the strength of the aluminum. This is one of the unique features of this process as it derives its strength from at least 3 main sources: the strength of the aluminum, the strength of the diffusion bonds between aluminum and steel, and the clinching/normal force of the rivet holding all three sheets together. More research needs to be done to characterize and optimize these in teractionsto achieve higher tensile strengths, but initial results show a new way of joining dissimilar metals that is significantly stronger thanother processes to date. This continuous rod/rivet of joined alu-minum within the preformed through hole greatly increases the strength of the joint and is what differentiates the two-sided FSR by extrusion process from other mechanical joining processes