Cold welding is the phenomenon of being able to join together primarily metallic workpieces of the same material at room temperature in such a way that the joint is very similar to "normal" welding; hence the name.
This phenomenon was discovered in the 1940s.
Cold pressure welds are created under high pressure and, unlike other welding methods, below the recrystallization temperature of the individual parts. The two parts remain in a solid state, but plastic deformation with strong adhesion of the contact surfaces is necessary. The intensive contact between the two contact surfaces results in a stable connection between the two workpieces.
For a good connection, materials with sufficient cold formability are required (e.g.: copper and aluminium to and with each other).
In individual cases a connection is also suitable for continuous power conduction. For this, prior degreasing and removal of the superficial oxide layer are helpful.