| Abstract Scope |
Friction self-piercing riveting (F-SPR) employs a rotating rivet to generate frictional heat, enabling crack free joining of high-strength, low-ductility aluminum alloys (AA). For an AA7075–AA7075–AA6022 3T stack with a thin AA6022 bottom sheet, the F-SPR process window is extremely narrow, requiring a balance between sufficient mechanical interlocking and strong solid-state bonding at bottom interface for mechanical joint performance while preventing over-piercing of the bottom AA6022.
In this study, a multi-step F-SPR process was developed to precisely control rivet penetration and flaring, resulting in robust joint integrity under manufacturing variations, including sheet thickness variation, gaps, and misalignment. Cross-sectional characterization and analytical analysis were conducted to evaluate mechanical interlock geometry, joint interface morphology, and solid-state bonding integrity. The relative contributions of mechanical interlocking and solid-state bonding to lap shear tensile performance were elucidated, establishing a manufacturing-variation-tolerant joining process for aluminum-intensive body-in-white vehicle structures. |