Improving the interfacial bonding strength and suppressing shrinkage porosity of 6061Al/GFRTP hot-pressing joints via interfacial modification

The application of metal-plastic hybrid structures is of great significance for structural lightweight. The metal surface treatment is critical for metal-plastic joints. In this study, nanosecond laser was used to construct different microscale grooves on 6061 aluminum alloy (6061Al) surface to realize stable joints with glass fiber reinforced thermoplastic composites (GFRTP) by hot-pressing joining. The impacts of nanosecond laser processing on interfacial bonding of 6061Al/GFRTP were studied using analytical methods and finite element simulations. The results showed that the mechanical interlocking effectively improved the strength of connections. Moreover, the laser texturing patterns had different effects on promoting the wettability of metal surface and improving the heat conduction path. During the hot-pressing joining process, the poor wettability of molten GFRTP on untextured metal surface and different solidification rates at various molten positions led to the formation of shrinkage, which reduced the bonding area and induced stress concentration. When the pitch distance of textured grooves was 0.3 mm, the porosity was reduced to 1.15 %, and the corresponding maximum bonding strength was 9.78 MPa.