Abstract

Ultra-fine-grained (UFG) Cu shows little total elongation in tensile tests because simple shear deformation is concentrated in narrow regions during the initial stage of plastic deformation. Here, we attempted to improve the total elongation of UFG Cu obtained by equal-channel angular pressing. By making shallow dents on the side surfaces of the plate-like specimens, this induced pure shear deformation and increased their total elongation. During the tensile tests, we observed the overall and local deformation of the dented and undented UFG Cu specimens. Using three-dimensional digital image correlation, we found that the dented specimens showed suppression of thickness reduction and delay in fracture by enhancement of pure shear deformation. However, the dented and undented specimens had the same ultimate tensile strength. These results provide us a new concept to increase total elongation of UFG materials.

Highlights

  • The strength of metallic materials can be improved by grain refinement

  • These results show that large simple shear deformation along equal-channel angular pressing (ECAP)-SD was caused for undented specimens during the initial stage of local deformation

  • These results indicate that the processing dents only changes the deformation behavior from simple shear deformation to pure shear deformation during the initial stage, and shear band localization occurs along ECAP-SD

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Summary

Introduction

The strength of metallic materials can be improved by grain refinement. One way to produce grain refinement is severe plastic deformation (SPD), which can reduce grain size to the submicron regime [1], producing ultra-fine-grained (UFG) materials. Local deformation of UFG materials is mainly caused by shear bands, and shear band localization leads to fracture. That is, their poor ductility has been attributed to the occurrence of shear band localization [9] during the initial stage of plastic deformation [7]. In our previous study [18], processing notches the side surfaces of plate-like specimens obtained by equal-channel angular pressing (ECAP). Present we attempted the of the wide region of pure shear deformation by applying this method. Measuring surface displacements is insufficient to evaluate the contribution of in-plane pure-to reduce shear band to localization. Three-dimensional digital image correlation (3D-DIC) in the present study

ECAP Processing and Plate-Like Tensile Specimens
Adding
Tensile Tests
Mechanical Properties
Analysis of Shear Strain
Comparing
Comparison
Fitting parametersbut u and for the dented undented
Conclusions

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