Cyclic extrusion compression angular pressing (CECAP) as a novel severe plastic deformation method for producing bulk ultrafine grained metals

Abstract

In the current study, a novel severe plastic deformation (SPD) technique entitled cyclic extrusion channel angular pressing (CECAP) is proposed appropriate for producing ultrafine grained cylindrical material. In this new method, cyclic extrusion compression (CEC) and equal channel angular pressing (ECAP) processes are combined which solves drawbacks of both processes. Advantageous of the new process may be considered in two views of points of processing and properties. This new process increases the hydrostatic compressive stress of ECAP as well as shear to the total strain of CEC. Also, CECAP solves needing back pressure problem of CEC process which is an important feature of the new process. The process treated an AZ91 alloy and remarkable grain refinement and significant improvement in strength, ductility and hardness were achieved because of higher hydrostatic compressive stresses.