Polymer–metal hybrid structures combine the merits of polymer and metal materials, making them widely applicable in fields such as aerospace and automotive industries. However, the main challenge lies in achieving efficient and strong connections between the metal and polymer components. This paper uses the jet electrochemical machining (Jet-ECM) method to customize the surface morphologies on 6061 aluminum alloy (AA6061) sheets. The connection between AA6061 and carbon fiber-reinforced PA66 (CF/PA66) is then achieved through hot pressure welding (HPW). The effects of aluminum alloy surface morphology, welding force, and welding time on the mechanical properties and microstructure of the joint are investigated. The optimal process parameters are determined by the design of the experiment. The results show that the aluminum alloy surface morphology has the greatest impact on the mechanical property of the welded joint. The optimal process parameters are surface morphology with wider, shallower, and sparsely distributed grooves on the aluminum alloy surface, the welding force is 720 N, the welding time is 12 s, the welding temperature is 360 °C, the cooling time is 16 s, and the optimal peak load of the joint is 6690 N. Under the optimal parameters, the fracture morphology in the AA6061 side is almost entirely covered with CF/PA66. The joint experiences cohesive failure in most areas and fiber-matrix debonding in a small area.

Diverse industries are witnessing an increase in demand for hybrid structures of metals and carbon-fiber-reinforced thermoplastic composites (CFRTPs). Welding is an essential technique in the manufacture of metal–CFRTP hybrid structures. However, achieving high-strength metal–CFRTP welded joints faces serious challenges due to the considerable disparities in material characteristics. As an effective method to strengthen metal–CFRTP joints, surface texturing on metal is gaining significant attention. This study introduces an emerging surface texturing approach, electrochemical jet machining (EJM) using a film electrolyte jet, for enhancing the performance of AA6061-CF/PA66 hot-pressure-welded (HPW) joints. Parametric effects on surface morphology and roughness in the EJM of AA6061 are investigated. The results show that a rough surface with multiscale pores can be generated on AA6061 by EJM, and that surface morphology can be modulated by adjusting the applied current density and jet translational speed. Subsequently, the effects of different EJM-textured surface morphologies on the performance of HPW joints are examined. Surface textures created by EJM are demonstrated to significantly enhance the mechanical interlocking effect at the bonding interface between AA6061 and CF/PA66, resulting in a substantial increase in joint strength. The maximum joint strength attained in the present work with EJM texturing is raised by 45.29% compared to the joints without surface texturing. Additionally, the joint strength slightly improves as the roughness of EJM-textured surfaces rises, with the exception of rough surfaces that are textured with a combination of low current density and rapid translational speed. Overall, these findings suggest that EJM texturing using a film jet prior to welding is a potential approach for the manufacture of high-performance metal–CFRTP hybrid structures.