Deformation lagging characteristics of IF steel disks in the plastic deformation process of high pressure torsion

Abstract

Deformation lagging characteristics of IF steel disks in the early torsion stage in the process of High-Pressure Torsion (HPT) are investigated with DEFORM-3D finite analysis software through the effective strain distribution of HPT sample by computer simulation and experimental verification. The results indicate that in the early torsion stage (not more than 2 turns), deformation lagging characteristics will exhibit remarkably in the severe plastic deformation (SPD) process. As to the Equivalent Von Mises strain, values in the sample edge is significantly higher than that in center, gradually decreasing from the edge to the center along the radius direction. Compared with the upper surface of sample, the effective strain of the bottom surface is obviously increasing. The SPD area in upper surface of sample is smaller than bottom surface of sample. Following the increasing rotation angel and the distance from the center, the deformation lagging characteristics of upper surface will appear more obviously. The mechanism of characteristics analysis indicate that the active rotation for the bottom die and friction plays an important role in the deformation lagging process. The theoretical analysis, the micro-structure and hardness investigation all agree well with the simulation results. © 2018, Science Press. All right reserved.