Abstract: Aiming at the joining mechanism of metal in cold welding, makes a comprehensive experimental determination to the diffusing action of atoms at the interface of cold welding joints by using a great deal of measuring experiments such as neutron activation, S. E. M. , spectral analysis, etc. It is pointed that there is no diffusing action between different types of metal in the measuring cold welding joints. Further observation and analysis on the interface of cold welding joints by T. E. M. , it is shown that joint interface area is composed of tiny crystals which are formed by extruding and breaking. These broken crystals bite on each other at the interface. This increases the physical contact area of the welded metal, forms intercrystal joint between broken crystals. So, the joining can be achieved without metal atoms diffusion. On the basis of the above analystic results, successful butt cold welding has been obtained between the metals of incoherent lattice and non-soluble liquidoid and non-soluble solidoid. Furthermore, it is shown the cold weld ability between the various combination of different types of metal.

Key words: Cold welding, Diffusing action, Joining mechanism