SIMULATION OF TWO-STAGE HOT FORGING OF POROUS WORKPIECES INVOLVING SEVERE PLASTIC DEFORMATION 

Abstract

The evolution of the stress-strain state and the relative density distribution throughout a porous workpiece during two-stage hot forging process was studied. The primary stage involved hot deformation of a cylindrical preform with the application of force to its lateral surface to form an intermediate semi-finished product with a cross-section shaped as a truncated cone. Further deformation in the secondary stage involved hot forging of the conical workpiece into a prism. These process stages were simulated using the finite-element method with the DEFORM 2D/3D software package. The starting preform was a cylinder with uniformly distributed porosity throughout the volume. The simulation results revealed significant uneven strains e_i across the workpiece following the primary process stage, resulting in an area with increased strains e_i concentrated near the upper punch. Conversely, the secondary process stage noticeably evened out the strain values across the forged workpiece. This occurred because the severe deformation area in the secondary process stage matched the stagnant area in the primary stage. The proposed two-stage deformation scheme achieved sufficiently high strains (1.3–1.7), allowing the production of forged materials with excellent mechanical properties.