Is cold welding real?

Yes, it is possible to weld in a cold or, more precisely, in a pasty state.
This process is based on the joining of two materials in a solid state without exceeding the melting temperature. Cold welding is used in particular on metal and plastic parts that can be deformed by heat. It is therefore a particularly interesting process for aluminium. Cold welding is also suitable for joining dissimilar materials.
Cold welding is generally used to design butt or lap/transparent joints.
Friction stir welding (FSW)/https://stirweld.com/en/friction-stir-welding-2/technology/] is one of the techniques for joining in the paste state.