PURPOSE: To eliminate a joining face structure and to obtain the joining part structure same as that of a base metal by heating at ≥a recrystallizing temp. with pressurizing in a vacuum, inert gas and reducing gas after applying a strain in a cold state on the crystal of the joining face, in the case of joining the metal members having the same component and same essential chemical component.

CONSTITUTION: As to how to apply a cold strain any method will do of a rolling, forging, machining, etc. if it can apply a cold strain on the crystal of a joining face. The strain enough to cause the working recrystallization by the joining metal is necessary for the amount of the working strain and the upper limit of the amount has no limitation if the adhesion at the joining time of a joining member be good. The strain amount of the joining faces to be faced does not need to be the same. As for the finishing of the joining face it is necessary to be smooth each other to the degrees that the joining member can be adhered sufficiently. A vacuum, inert gas or reducing gas atmosphere is necessary for preventing the oxidation of the joining face as to the atmosphere at joining time. The pressurizing force same as conventional one is necessary for the pressure at the joining time but a higher working force is better. It is necessary to heat at the temp. causing a working recrystallization on the joining metal as to the joining temp.