Relationship among joined tubular material properties, joining behavior and performance by elastomeric swaging

Joining by elastomeric swaging (ES) is a deformation-based way to manufacture tubular form-fit joints composed of aluminum alloy (AA) tubes and high-strength steel sleeve-fittings. To explore the relationship among the joined tubular material properties, joining behavior and performance of tubular form-fit joints fabricated by elastomeric swaging (ES), this paper took 6061-T4 and 5052-O AA tubes as material cases and carried out a comprehensive investigation by modeling and experiments. In terms of these two AA tubes, their microstructure was characterized by means of EBSD; their mechanical properties were characterized by tension tests based on digital image correlation and Visco-plasticity Self Consistent modeling. The characterization results demonstrate that the 6061-T4 tube has precipitation strengthening mechanism, texture unfavorable to shear, no Portevin–Le Chatelier (PLC) effect, larger strain hardening exponent and higher strength. In view of process, based on the material modeling for anisotropic AA tubes, hyperelastic polyurethane elastomer hose and 15-5PH sleeve, implicit axisymmetric numerical models of ES joining process with loading and unloading were established and validated. The simulation results show that there is a larger normal deformation in the 5052-O tube under the same extrusion depth and rate, and at the same bulging heights as 5052-O, the 6061-T4 tubular joints have larger residual contact shear stress at the undercuts. As for service performance, the ES joining tests and joining performance verification experiments were carried out. The experimental results show that the 6061-T4 tubular joining components have higher pressure resistance, larger pull-out force and better fatigue endurance. In conclusion, the joined tubes with texture unfavorable to shear, higher strength, larger strain hardening exponent and no PLC effect are beneficial to forming form-fit joints.