Electric vehicles (EV) offer the automotive industry the potential to meet future emission targets and develop alternative drive systems. These systems require several thousand single battery cells to be joined together. The battery cells are complex assemblies of dissimilar materials with very low thicknesses, which presents a significant challenge during the joining process, especially welding. We have investigated the effect of pulse arc welding, as well as laser welding using fiber laser (1070 nm) in pulse mode and blue wavelength laser (450 nm) in continuous mode, for joining low thickness dissimilar materials. The parametric study for good quality weld samples based on high tensile strength, was performed using 0.3mm thickness nickel coated copper tabs joined to 0.6mm thickness mild steel. The best performing process parameters were then employed to join battery cells inside the battery module. The microstructure of weld samples was investigated using optical microscopy as well as scanning electronic microscopy (SEM). The mechanical performance of weld samples was characterised through tensile testing along with micro hardness measurements to identify the microstructure property relationship. The microstructure investigations showed the heat conduction welding mode for pulse arc and blue wavelength laser, while keyhole penetration welding mode for fiber laser. Depending on the welding process, the maximum ultimate tensile strength (UTS) of the weld samples varied from 660N to 1200N. Micro hardness measurements revealed significant increase in hardness of weld nugget, compared to parent materials when welded using laser. When compared with microstructure, this is attributed to the formation of Cu-Fe composite microstructure inside weld.
|Number of pages||1|
|Publication status||Published - May 2020|
|Event||THERMEC'2020: 11th International Conference on the advanced materials. - Vienna, Austria|
Duration: 31 May 2020 → 5 Jun 2020
|Conference||THERMEC'2020: 11th International Conference on the advanced materials.|
|Period||31/05/20 → 5/06/20|