The invention relates to a device and a method for preparing fine-grained material by directly extruding a
continuous variable cross section, which relate to a device and a method for preparing fine-grained material. The invention solves the problems of the traditional fine-grained material preparation methods that the procedures are complicated, the
process requirements are high, the
texture orientation is significant, the defects of folds and material interface superposition are easy to occur in
processing and preparation and the preparation methods are difficult to be implemented in production. A primary transition die cavity, a secondary transition die cavity and a core die cavity of the preparation device of the invention are combined to form an axial corrugated
extrusion cavity of the
continuous variable cross section; the preparation method of the invention comprises the following steps: the preparation device is assembled; an
ingot is arranged in a female die, a punch head is put it, a punch head is put in, the die orifice on a core die
extrusion end is closed, the punch head descends, the
ingot is extruded form a primary transition die orifice and a secondary transition die orifice, the punch head continues to descend, and the
ingot is upset and deforms; and the closure is removed, the punch head continues to descend, and the ingot is extruded and formed. The invention requires simple equipment and few production procedures, and is easy to be implemented and popularized in production.