A feasibility study of electrically assisted solid-state spot joining (EASSJ) of dissimilar aluminum alloys for automobile structures was conducted. EASSJ of dissimilar automotive aluminum alloys (AA6451 and AA6014) was conducted by simultaneously applying step-by-step current and compressive load to the faying interface (lap spot joining), while the temperature was controlled to be lower than melting points of joining alloys. To evaluate the soundness of the joint, a nugget pull-out fracture mode under shear tensile test was set as a criterion. Microstructure analysis was also conducted to evaluate characteristics of the joint. Experimental results suggest that the EASSJ is clearly feasible in joining dissimilar aluminum alloys for automobile structures.

The adhesive bonding technology of carbon fiber reinforced plastics (CFRP) and aluminum alloys, is one of the lightweight joining technologies for automobiles. The strength and properties of the bonded joint, depend on the surface of the bonded part that the adhesive touches. Thus, proper surface treatment is one of the most important steps in the bonding process. The laser surface treatment of carbon fiber composites is a new form of green and environmental surface treatment technology, which can effectively clean coatings and pollutants on the surface of materials. It is also possible to improve the bonding shear strength, by changing the microstructure and roughness of the material surface through laser micro texture processing, to form a mechanically interlocked structure. In this study, a pulsed laser was used to treat the surface of CFRP. By changing the scanning line spacing during laser micro texturing, the effect of laser micro texturing on the surface morphology of CFRP and the strength of aluminum alloy bonded joints was investigated. Results show that in the laser micro texturing process, when the scanning line spacing was 0.3 mm, the maximum tensile shear strength was 14.5 MPa, approximately 200% higher than that without laser treatment.