Hybrid laser technique for joining of polymer and titanium alloy

Weight reduction of parts is of great importance in automotive and aerospace industries. Laser direct joining of dissimilar materials had been investigated previously to obtain lightweight characteristics and keep the local excellent plasticity and mechanical property. In the present work, the authors adopt the hybrid laser joining method to bond Ti6Al4V and polyamide (PA66). Laser texturing pretreatment is performed on the Ti6Al4V surface prior to the laser joining process. Oblique microgrooves with the depth ranging from 100 to 550 μm are designed and fabricated on Ti6Al4V surfaces to improve the bonding strength between Ti6Al4V and polyamide. Single lap shear tests are carried out after the laser joining process. The highest breaking force of laser joined Ti6Al4V-PA66 joints reaches around 942 N, which is high up to more than 90% of base PA66 breaking force (1043 N) and about 4.9 times of the joints with a smooth Ti6Al4V surface (194 N). The great enhancement of breaking force of the joints is attributed to the strong mechanical bonding quality between PA66 and surface-textured Ti6Al4V. The employed hybrid laser joining method shows great potential in manufacturing industries.