Influence of laser process parameters and fiber content on interface properties of GFRPP -aluminum alloy composite by hot press molding

Glass fiber-reinforced polypropylene (GFRPP) is widely used in the automotive, aerospace, and other industries due to its advantages of low weight, high strength, corrosion resistance, and low cost. However, insufficient interfacial bonding strength between GFRPP and aluminum alloy limits the performance and reliability of composite structures. In this paper, a grid-like micro-texture was fabricated on the aluminum alloy surface using laser processing, and a mechanical interlocking joint with GFRPP was achieved by hot press molding. The effects of the number of laser scanning passes, grid spacing, and glass fiber content on interfacial bonding performance were systematically investigated. The results showed that joint strength was optimized when the number of laser scanning passes was 10 and the grid spacing was 0.1 mm, while the interfacial performance was optimal when the glass fiber content was 20%. The tensile strength and yield strength of GFRPP increased by up to 97.93% and 126.90%, respectively compared to pure polypropylene. Analysis of the interfacial micromorphology revealed that the laser-textured structure formed effective mechanical interlocking with the GFRPP melt, transforming the interfacial failure mode from brittle interfacial debonding to matrix cohesive failure, thereby enhancing interfacial bonding strength and fracture toughness.