Role of Strain Reversal in Microstructure and Texture of Pure Al during Non-Monotonic Simple Shear Straining

Ebad Bagherpour,Ramin Ebrahimi,Hiroyuki Miyamoto,Fathallah Qods,Mohsen Reihanian

doi:10.3390/cryst10100926

Abstract

The effect of reverse straining on the microstructure, texture, and hardness of the pure Al during the single cycle of the simple shear extrusion (SSE) process is investigated. Electron backscattering diffraction (EBSD), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM) are used for microstructural evaluations. Due to the nature of the SSE process, the direction of the shear is reversed in the second half channel. As a result, the mean misorientation angle, dislocation density, and hardness decrease. The grain size increases to some extent in the exit of the channel compared with that in the middle. The structural evolution during the single pass of SSE is described in terms of the dislocation cancelling, “untangling” of the cell walls and disintegration of the “forward” cell structure due to the reverse straining in the second half channel. Some simple shear components replace the first texture component in the middle of the channel. At the exit of the channel, the primary texture components appear somewhat confirming the strain reversal effect in the second half channel.

Highlights

When a material is loaded in tension and subsequently in compression, the yield stress in compression is lower than the tensile yield stress
The electron backscattering diffraction (EBSD), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM) were used for microstructure, texture, and hardness evaluation in pure Al through a cycle of non-monotonic simple shear strain to investigate the effect of the strain reversal
Application of a single cycle of simple shear extrusion (SSE) caused the large and equiaxed grain structure to replace with fully elongated grains at the centre and less elongated ones at the samples’ surface

Summary

Introduction

When a material is loaded in tension and subsequently in compression, the yield stress in compression is lower than the tensile yield stress. This is called the Bauschinger effect [1]. The strain reversal can affect its impact on microstructure and mechanical behaviour. The deformation behaviour of the material differs during forward and reverse straining. The competition between dislocation storage and the disappearance of the dislocations accumulated during the forward straining attribute to such action [3,4]. Though the reversal deformation mode cannot significantly affect the grain refinement, the strain reversal potentially delays the formation of high angle grain boundaries (HAGBs) compared

Methods

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Discussion

Conclusion