The effect of initial strain in the severe plastic deformation of aluminum on the subsequent work hardening regeneration through low strain amplitude multi-directional forging

Abstract

Work hardening caused by Severe Plastic Deformation (SPD) strengthens ductile metals remarkably but practically annihilates their further work hardening during monotonic post-SPD deformation. Low Strain Amplitude Multi-Directional Forging (LSA-MDF) after one Equal Channel Angular Pressing (ECAP) pass of aluminum causes limited softening and regenerates its work hardening capacity. The full development of an SPD condition in aluminum demands an initial deformation higher than that associated with one ECAP pass. The present research analyzes the application of LSA-MDF to aluminum after 4 ECAP passes. A regeneration of the work hardening capacity of the material was observed. In addition, LSA-MDF caused an increased fraction of High Angle Grain Boundaries (HAGBs) in the material and a decrease in the presence of distorted grains displaying internal dislocation structures.