PURPOSE: To manufacture strong structural metallic material by giving repeated forming to single crystal ingot and hardening it.

CONSTITUTION: The single crystal ingot such as Al, etc., is cast by hot casting type continuous casting and the ingot made up of single solid solution of Al radical free from solidification grain boundary undergoes repeated forging changing pressure directions in the cold. In this case, metals capable of melt casting and work hardening such as Cu, Ni, Fe, Co, Mg can be enumerated as applied material. As a result, hard, strong, structural metallic material excellent in fatigue resistance can be manufactured.