Scaling up and deformation control of severe plastic deformation processes

Abstract

Severe plastic deformation (SPD) process had many attentions for effective method of producing ultrafine-grained materials, but it had disadvantage of low productivity. In this study, for equal-channel angular pressing (ECAP) and high-pressure torsion (HPT), development of application process was conducted to overcome such drawback. In the case of the ECAP process, the study was conducted in the direction of sample enlargement. The diameter of the 42 mm rod specimen was treated with ECAP 8 passes of route BC. The microstructure and tensile properties were analyzed to confirm that effect from the process scaling up. In the case of the HPT process, the control of deformation region was the direction of improvement, and this method was called band concept. The band concept was applied to hollow cone high pressure torsion (HC-HPT) process in this study, thus it called band hollow cone high pressure torsion (BHC-HPT). The BHC-HPT process carried out 1 and 3 revolutions, and the mechanical properties and microstructures were analyzed to verify the effect of the band concept. In addition, the finite element method simulation was performed for BHC-HPT to calculate the strain distribution after the process. As a results, this study showed that the SPD still have many possibilities, and provided direction how the SPD should be changed to achieve the industrialization.