Cold welding is at times referred to as Diffusion welding, Cold welding is a solid state process in which pressure is used at or near room temperature to produce a type of coalescence of metals with considerable deformation at the cold weld zone. Pressure for welding can be from a number of different types of systems such as mechanical presses, rolls and in some cases for very small work even hand operated tools.
With this process there is a total absence of heat created during the process.
Soft materials are best suited for cold welding, hardened or heat treated alloys are more difficult and in some cases imposable to cold weld.
One of the useful aspects of this process is that dissimilar metals can be joined in this process. The process is far from new ,it's been around for years.