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Electromagnetic pulse spot welding technology (EPSW) has great application prospects in the field of electric vehicles due to the realization of spot welding without gasket. The EPSW of Cu/Al alloy in this article is carried out in two steps. The first step uses electromagnetic force to pre-process the aluminum plate to punch a hump through electromagnetic pulse forming (EMPF). The second step uses electromagnetic force to realize spot welding between the hump and the copper plate. This article studied effects of stamping and spot welding with discharge voltage between 10 kV and 15 kV and compared welding effects of spot welding with coils of different widths. The results show: electromagnetic pulse spot welding technology without gasket was realized; the higher the discharge voltage, the better the stamping effect and spot welding performance; the wide coil can achieve a flat welding interface while the narrow coil can achieve reliable connection at a lower discharge voltage.

Electromagnetic pulse crimping (EMPC) technology is expected to be applied to the connection of high-voltage (HV) wiring harnesses and terminals for electric vehicle (EV). As an important part of the EMPC system, the assembly of the field shaper and the coil can directly affect the effect of EMPC. An EMPC system was established in this work, including the control part, energy storage capacitor bank, discharge switch, coil, and field shaper. The relationship between structure parameters of the field shaper and the coil was analyzed through the EMPC experiment of Al tubes. The results showed that the relative position and height of field shaper and coil have no obvious effect on the deformation length of the Al tube. When the angle between the gap of the field shaper and the gap of the coil is 90°, the deformation of Al tube is the most uniform. When the total height of field shaper is slightly less than the welding coil, the crimping effect is the best. This work can help design the field shaper and the coil for EMPC.

To determine the velocity field in which the Ti-6Al-4V titanium alloy sheet was sensitive to the strain rate, the formability at different strain rates were tested using a ring sample in the electromagnetic ring expansion experiment. For the test of titanium alloy, an aluminum alloy loop was used as a driver ring due to improve energy efficiency. The expansion velocity and strain rate of titanium ring were predicted by a numerical simulation method which had been verified by experimental data obtained with a high speed camera. The uniform strain was defined as the ratio of the change and the one after expansion of the cross sectional area in this study. Since the fracture strain of a material was related to the aspect ratio (ratio of length to diameter) of samples, the uniform strain was chosen to characterize the ductility of the material. The results indicate that when the tensile speed of Ti-6Al-4V titanium alloy sample is 2 mm/min (quasi-static), the strain rate of deformation is 6.67×10-4 1/s and its uniform strain (ɛu) reaches 0.102. Instead, the uniform strain is only 0.032 when the expanding speed of 46.7 m/s is faster than the quasi-static speed. However, the uniform strain increases proportionally with the increment of the strain rate, and exceeds the quasi-static uniform strain reaching 0.11 or more when the deformation speed is faster than 286 m/s, in which the strain rate exceeded 6935.6/s. Therefore, the deformation speed of 286 m/s or the strain rate of 6935.6 1/s could be considered as the threshold to improve the ductility of Ti-6Al-4V titanium alloy.