Deformation Heterogeneities in Equal Channel Angular Pressing

抄録

Equal channel angular pressing (ECAP) is a severe plastic deformation (SPD) technique leading to refinement of the grain size of materials to submicron or even nano-size length scales. As a result SPD processed materials simultaneously possess high strength and moderate ductility and therefore have a high potential for technical applications. Because of this, much work has been devoted to the evolution of microstructure and texture and their relation to the mechanical properties. However, pressing materials through an angled channel is a complicated deformation process leading to deformation heterogeneities across the billet cross section manifested in gradients of microstructure and texture. Therefore, it is the aim of the present paper to give an overview focusing on the ECAP specific deformation heterogeneities and their related strength gradient in the billets produced. Based on the results reported, which are gained from experiment and simulation, some general conclusions on minimizing the deformation heterogeneities in ECAP are drawn.

Equal channel angular pressing of colored plasticine visualizing the inhomogeneous straining taking place in this severe plastic deformation process due to friction of the billet at the die walls. With increasing friction an open corner gap is closed and a dead metal zone (DMZ) forms. The inhomogeneous deformation leads to heterogeneities in microstructure, texture and mechanical properties across the billet.