Is spot welding possible for aluminum alloy?

It is possible.
Aluminum alloys require large currents because of the lower specific resistance of the material compared to steel sheets.
In addition, since there is an oxide film on the surface, it is necessary to remove the oxide film with a stainless steel wire brush or the like, in order to stabilize the welding quality.
When observing the cross-section of the weld, so-called blowholes may be seen inside the nugget.Blowholes can be reduced by increasing the electrode force (called forging pressure) from the second half of the welding cycle or by applying post-heating current to prevent rapid cooling.
Recently, robotics and welding control devices that can synchronously control welding current and electrode force have been introduced to the market.
Aluminum tends to adhere to the electrode surface, which may result in inconsistent weld quality or excessive weld marks. Therefore, tip dressing is required frequently.