Investigation on the Strain Distribution in Tube High-Pressure Shearing

Jiajie Meng,Zheng Li,Yebin Zhu,Ying Liu,Shun Wang,Jingtao Wang,Kui Lin,Jiaqiang Tao

doi:10.3390/met9101117

Abstract

The Finite-element method (FEM) and experiments were used to investigate the geometric factors and material parameter on the strain distribution during tube high-pressure shearing (t-HPS). The results show that t-HPS could be realized successfully either by pressurizing on both ends of the tube, or by pressurizing using the wedge effect; and in both cases, the “dead metal zone” could be found at both ends of the tube. The grain size distribution from the experiment confirmed this strain distribution feature. In the case of t-HPS pressurized using the wedge effect, the half cone angle has little effect on the strain distribution. Decreasing the strain-hardening exponent leads to increased deformation inhomogeneity in both the ideal t-HPS described by theoretical equations and the close to practical t-HPS described by FEM. This feature of t-HPS stands out from other SPD processes like HPT, and makes practical t-HPS behavior more predictable using the analytical formation than any other SPD processes, and places it an advantageous position in understanding the basics of deformation physics through the coupling between practical experiments and theoretical approaches.

Highlights

High Pressure Torsion (HPT) [1] is recognized as an effective way to produce ultra-fine grained (UFG) materials [2]
Were introduced as new methods for severe plastic deformation (SPD). These processes are same as HPT in the sense that a simple shearing process is driven by the stick friction between the dies and sample under high hydrostatic pressure. They are different to HPT in that the normal location of the shearing plane is parallel to radius of the tubular sample during tube high-pressure shearing (t-HPS) [3,5], whereas the normal location of the shearing plane is parallel to the axial of the disk sample for HPT
The principle [3] of t-HPS is that the tubular sample is confined between the mandrel and the cylinder, and a sufficiently high hydrostatic pressure is introduced in the tube wall so that the frictional forces at the interfaces between the sample-mandrel or cylinder are high enough to prevent any localized slip

Summary

Introduction

High Pressure Torsion (HPT) [1] is recognized as an effective way to produce ultra-fine grained (UFG) materials [2]. Were introduced as new methods for severe plastic deformation (SPD) These processes are same as HPT in the sense that a simple shearing process is driven by the stick friction between the dies and sample under high hydrostatic pressure. They are different to HPT in that the normal location of the shearing plane is parallel to radius of the tubular sample during t-HPS [3,5], whereas the normal location of the shearing plane is parallel to the axial of the disk sample for HPT. The mandrel is subjected to an axial load, which is transformed into the normal force on the contact surfaces between the sample-mandrel or cylinder and magnified by the principle of the wedge effect, so that a high hydrostatic pressure is introduced in the sample

Methods

Results

Discussion

Conclusion