Bonding behavior of fusion bonded hybrid joints with press hardened steel and glass mat reinforced thermoplastic

The aim of this investigation is to generate a basic understanding of the formation of the joining zone of fusion bonded hybrid joints made of press hardened steel (22MnB5) and polyamide 6 (PA6) glass mat reinforced thermoplastic (GMT). To this end, lap-shear samples are produced by varying the steel surface and the fusion bonding temperature. In order to evaluate the resulting joint properties, micrographs of the joining zone are analyzed. Moreover, roughness measurements, scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) investigations are used to characterize the steel surface and undercut geometries before joining. By correlating the results of the interface characterization with the mechanical joint strength, optimized fusion bonding parameters can be defined. The results outline the necessity of heating the metal above the melting temperature of the GMT material in order to prevent a solidification in the joining zone. Additionally, the GMT material has to be melted completely to allow the GMT to flow into the geometry undercuts of the AlSi surface. The maximum lap-shear strength is 22.9 +/- 2.1 MPa. It was achieved with the samples showing to a metal temperature of 280 degrees C and a GMT temperature of 260 degrees C.