PURPOSE: To obtain an alloy material having no striated defects equal to the defects when the hot-rolled blank material obtained from a continuously cast blank material by heating said blank material then subjecting the material to hot working to fine the structure of the surface layers followed by hot extrusion working.

CONSTITUTION: A dummy block 2 is placed on the trailing end of a continuously cast blank material 1 which is lubricated on the outside surface, and the block is forced forward from behind the block by means of a stem 3 to pass the material 1 through an extrusion die 4 until the material is forced into a container 5. At the point of the time when the working ends, the surface layers of the material 1 are recrystallized to at least 3mm thickness by the heat that the material possesses in the container 5, whereby fine crystal grains are formed in said layers. The material 1 having the surface layers of the fine crystal grains is pressurized from behind by the ram 3 in succession and while a glass lubricant is supplied from a disc 7, the material is passed through an extrusion die 6 having a desired hole diameter, whereby an extruded product 8 is obtained. Since the material 1 has the same fine structure as that of the hot rolled blank material resulted from the breakage of the cast structure prior to working with the die 6, the material produces no striated defects which are produced with conventional continuously cast blank materials even if said material is worked with the die 6.