Laser based surface texturing and PA6 powder interlayering for joining enhancement of DP600/PA6GF47 hybrid joints via induction welding

• The innovative combination of laser surface texturing and the application of a thin PA6 powder layer at the interface significantly improved the mechanical strength of the metal–composite hybrid joints by leveraging both mechanical interlocking and chemical adhesion. • Under optimized conditions (laser power of 1,75 kW and heating time of 3,5 s), the joints achieved a maximum shear strength of 19,5 MPa, representing a 170% increase compared to untreated joints. • The laser texturing created controlled microstructures on the DP600 steel surface, promoting infiltration of the molten polymer into these grooves and enhancing the mechanical interlock at the metal–composite interface. • The PA6 powder layer acted as an interfacial bonding agent, completely filling the surface microstructures and eliminating voids that would otherwise weaken the joint. • Fracture analysis revealed a shift toward mixed-mode failures, including fiber pull-out and cohesive failure within the composite matrix, confirming the improved interfacial bonding achieved through the integrated texture–powder approach. • Although the results are highly promising, the study emphasizes the need to assess the long-term durability of the joints and further optimize process parameters for large-scale implementation. This study investigates a novel approach combining laser surface microtexturing with PA6 powder interlayering to enhance the joining performance of DP600 steel/PA6GF47 thermoplastic composite hybrid joints via induction welding. Four joining conditions were evaluated: no texture-no powder (NT-NP), no texture-powder (NT-P), texture-no powder (T-NP), and texture-powder (T-P). Laser texturing parameters were optimized to create controlled micro-groove patterns with uniform depth and periodicity on DP600 steel surface. A thin PA6 powder layer was applied at the bonding interface prior to induction welding. Mechanical testing revealed that the combined texture-powder (T-P) configuration achieved the highest shear strength of 19,5 MPa, representing a 170% improvement over untreated joints (7,2 MPa). Microscopic analysis demonstrated that the synergistic effect of laser texturing and powder interlayering promotes complete polymer infiltration into surface microstructures, creating robust mechanical interlocking. Thermal analysis confirmed optimal processing temperatures for PA6 melting without degradation. The fracture mode shifted from interfacial failure to mixed-mode failure with fibre pull-out, indicating superior metal-composite bonding. This integrated approach offers a promising solution for lightweight structural assemblies in automotive and aerospace applications.