Patent ID: 8394214

Claim:
A method for processing an elongated metal body, comprising: moving the elongated metal body in an extending direction of the elongated metal body; heating the elongated metal body locally up to a temperature for performing solution heat treatment of the elongated metal body thus forming a low deformation resistance region; deforming the elongated metal body at the low deformation resistance region by twisting and spraying the elongated metal body, said twisting comprising twisting, the elongated metal body about a rotational axis of the elongated metal body arranged substantially parallel to the extending direction of the metal body by application of torsional force, said spraying comprising spraying water to the elongated metal body at each of two sides of the low deformation resistance region, so that a minute width along the extending direction is set in the low deformation region, and so that the elongated metal body is quenched at one of the two sides of the low deformation resistance region where the metal structure of the elongated metal body is turned into finer grain structure and an amount of addition elements placed in solid solution is increased; and performing aging treatment by maintaining the elongated metal body at a temperature which does not turn the metal structure into coarser grain structure after turning the metal structure of the elongated metal body into the finer grain structure.