Determination of the stress state and the specific force during severe plastic deformation in a closed die

Abstract

This article describes the results of a study that looked at the stress state and the specific force or contact pressure through the application of the slip line method and computer simulation (i.e. using the Deform 3D software package) when a workpiece was subjected to severe plastic deformation (SPD) in a special closed die. SPD is achieved when a flat punch is embedded in a round workpiece enclosed in the die and alternately compressed by a ring-shaped punch. Analysis of the results shows that compressive stresses prevail in the deformation zone resulting in the production of blanks with ultrafine-grained and/or nanostructure, as well as high mechanical properties. The relative discrepancy between the results obtained through the slip line method and those obtained through modelling in Deform 3D was about 1.3% indicating that the results can be considered reliable. It should be noted that this closed-die technique can be used to produce such products as gears, i.e. heavy-duty parts.