Pressure-Assisted Tube Cyclic Expansion Extrusion (Pa-TCEE) as a Sever Plastic Deformation Method for Processing of Fine-Grained Copper Tubes

Haddadi, Elyas; Jafarzadeh, Hossein; Zakeri Mehrabad, Vahid; Hashemi, Gholamreza

doi:10.22034/stme.2026.576746.1204

Pressure-Assisted Tube Cyclic Expansion Extrusion (Pa-TCEE) as a Sever Plastic Deformation Method for Processing of Fine-Grained Copper Tubes

Articles in Press

Document Type : Original Article

Authors

Elyas Haddadi ¹

Hossein Jafarzadeh ²

Vahid Zakeri Mehrabad ³

Gholamreza Hashemi ⁴

¹ Department of Mechanical Engineering, Technical and Vocational University (TVU), Tehran, Iran

² Department of Mechanical Engineering, Islamic Azad University, Tabriz branch, Tabriz, Iran

³ ,Department of Mechanical EngineeringTa.C., Islamic Azad University, Tabriz branch ,Tabriz, Iran

⁴ Space Thrusters Research Institute, Iranian Space Research Center, Tabriz, Iran

10.22034/stme.2026.576746.1204

Abstract

In this study, a novel severe plastic deformation technique entitled Pressure-Assisted Tube Cyclic Expansion Extrusion (Pa-TCEE) was developed to produce fine-grained (FG) copper tubes. Commercially pure copper tubes with an outer diameter of 10 mm, wall thickness of 1.2 mm, and length of 60 mm were subjected to consecutive expansion–extrusion cycles within a closed die without disassembly. To suppress structural instabilities such as buckling and wrinkling, the tube interior was filled with lead as an interfacial medium to generate internal pressure. Tensile test results revealed that the yield strength of copper increased significantly from approximately 120 MPa in the as-received condition to about 230 MPa after the first pass, accompanied by an improvement in ultimate tensile strength with increasing number of passes. The hardness increased from an initial value of 66 HV, approaching a softening state after multiple passes. Microstructural observations indicated a remarkable grain refinement from an average grain size of about 50 µm in the initial material to a fine-grained structure after three passes. These findings demonstrate that the Pa-TCEE process is an effective and scalable SPD technique for continuous production of FG copper tubes.

Keywords

severe plastic deformation

fine-grained structure

cyclic expansion extrusion

internal pressure

Pa-TCEE

Subjects