Downscaling Equal Channel Angular Pressing

Abstract

ECAP (equal channel angular pressing) is a well-known severe plastic deformation method used to produce ultra-fine grained materials. The dimensions of ECAP specimens are usually in the centimeter range. For producing high strength wires or fibres with diameter in the micrometer/millimeter range, downscaling of the ECAP process may be a viable option. To achieve this, several experiments were carried out. For downscaling to the micrometer range, porous steel discs can be used as processing tools. In this case, a solid state infiltration method as a variant of the forcefill process can be used. Extremely large strain is introduced due to the material flow through the tortuous channels inside a porous pre-form leading to grain refinement depending on processing conditions. To obtain specimens with a typical dimension in the millimeter range, the forcefill approach was altered by using die channels produced by conventional drilling. The tool geometry used is equivalent to conventional ECAP, but with a multi-channel die. Microstructure investigations demonstrating significant grain refinement confirm the viability of this approach.