Formulae have been obtained that are necessary to calculate cumulative deformation in the process of straitened extrusion in the central area closed to the working end of the counterpunch. The general method of plastic flow proposed by A. L. Vorontsov was used. The obtained formulae allow one to determine the deformed state of a billet in any point of the given area. The formulae should be used to take into account the strengthening of the extruded material.
